Title of Invention	LIFT INSTALLATION WITH A MEASURING SYSTEM FOR DETERMINING ABSOLUTE CAGE POSITION
Abstract	The present invention relates to a lift installation with a length measuring system for determining a cage position of a lift cage movable along at least one guide rail, a code mark mounted near the lift cage and parallel to the travel direction, a code reading device, which is mounted on the lift cage, for contactless scanning of the code mark pattern and an evaluating unit for evaluating scanned. code mark patterns, characterized in that n successive code marks of the code mark pattern form a code word, that code words are unambiguously arranged in an n-digit pseudo random sequence of different code words, that the code words form a' single-track code mark pattern and that a scanned code word represents an absolute cage position.

Title of Invention

LIFT INSTALLATION WITH A MEASURING SYSTEM FOR DETERMINING ABSOLUTE CAGE POSITION

Abstract

The present invention relates to a lift installation with a length measuring system for determining a cage position of a lift cage movable along at least one guide rail, a code mark mounted near the lift cage and parallel to the travel direction, a code reading device, which is mounted on the lift cage, for contactless scanning of the code mark pattern and an evaluating unit for evaluating scanned. code mark patterns, characterized in that n successive code marks of the code mark pattern form a code word, that code words are unambiguously arranged in an n-digit pseudo random sequence of different code words, that the code words form a' single-track code mark pattern and that a scanned code word represents an absolute cage position.

Full Text	U 1J1 f Translation of Application amended for national phase Lift installation with a measuring system for determining absolute cage position The invention relates to a lift installation with a measuring system for determining the absolute cage position of a lift cage movable along at least one guide rail, according to the definition of the patent claims. In lifts, the positional information is applied in coded form in stationary position along the entire travel path of the lift cage and is read off in coded form by means of a code reading device and passed on to an evaluating unit. The evaluating unit prepares the read-off coded positional information to be comprehensible by a control and derives therefrom data signals which are passed on to the lift control as so-termed shaft data. An absolute measuring system with high resolution for determination of the relative position of two parts movable relative to one another is known from DE 42 09 629 A1. In hitherto conventional manner an absolute code mark pattern in the form of a gapless sequence of equal-length code marks of a pseudo random coding are formed there at a first part in a first track and an incremental code symbol pattern is formed there in a second track parallel thereto. In the absolute code mark pattern, any n successive code marks in each instance represent a code word. Each of these code words is present only once in the entire code mark pattern. A code reading device, which can detect n successive code marks all at once in movement direction and in that case scans the incremental code symbol pattern, is provided at a second part movable relative to the first part. If the code reading device is moved along the first part by one code mark position of the absolute code mark pattern, a new n-digit binary code word is read. In this known device each code word of the absolute code mark pattern defines a specific position of the two parts relative to one another. The length, which is measured in the direction of movement or reading, of the individual code marks and the number of the maximum possible code words establish the maximum length of the measuring path able to be addressed by code words. The resolution capability by which the relative position, i.e. the so-termed position code, expressed in the pseudo random code can be measured depends on the length of each individual code mark. The smaller the length of the code marks, the more accurate the positioning can be. However, reading-off becomes noticeably more difficult with decreasing lengths of the code marks, particularly in the case of high relative speeds. I ransiation ot Application amended for national phase In the case of use of such an absolute length measuring system for determining the position of a lift cage, such as, for example, the lift known from German Utility Model G 92 10 996.9t the entire travel path in the travel direction of the lift cage is to be addressed in gapless manner with coded position details, i.e. the code words of the pseudo random coding. The maximum of the measuring or travel path extent is then, however, limited by the sum of the length of all code marks. A pseudo random coding with multi-digit code words and/or code marks of greater length accordingly has to be provided for long travel paths. However, multi-digit code words necessitate correspondingly complicated code reading devices and evaluating units and this is connected with high costs. With increasing length of the individual code marks, however, the resolution capability diminishes. In order to avoid errors in reading, the absolute code mark pattern and the incremental code symbol pattern are to be represented in their relative position exactly aligned with one another. This makes the production of a double-track code carrier expensive and moreover necessitates a time-consumingly precise mounting. In addition, the code reading device, in particular, of a double-track absolute position measuring system is of large construction, which is undesirable with respect to the limited shaft cross-sectional area available. Furthermore, the travel speed in the case of double-track measuring systems is limited, which is felt to be limiting especially for lifts with large conveying weights. The object of the invention is to indicate a lift of the kind described in the introduction with a measuring system for determining the absolute position of the lift cage, which enables a nigh-resolution in the position recognition over a long travel path of the lift cage with smallest possible expenditure. \ccording to the invention this object is met by a lift with an absolute position measuring system with the features of claim 1, which is distinguished particularly by the fact that the absolute code mark pattern and the incremental code symbol pattern are represented as a single-track, combined code mark pattern of n-digit pseudo random sequence in Manchester coding and the code reading device comprises sensors for scanning n + 1 successive code marks, wherein each second code mark of the single-track, combined ■nark pattern is scanned. Translation of Application amended for national phase The essence of the invention consists in a single-track coding for an absolute length measuring system in which starting from a binary n-digit pseudo random sequence, by which T - 1 different position values are coded, a 1 is inserted behind each 0 and a 0 is inserted behind each 1. The thereby-obtained sequence according to the invention with double length represents quasi a combination of the n-digit pseudo random coding and a Manchester coding. So that all code words arising in the combined code mark pattern according to the invention differ from one another, n + 1 code marks of the respective second code marks of the combined code mark pattern have to be scanned. The advantages of absolute single-track systems are combined, by the coding according to the invention, with the advantage of the high resolution of the absolute double-track or multiple-track systems. By the combined coding according to the invention there can be represented, by an n-digit pseudo random coding with unchanged resolution, a measuring path twice as long as that corresponding with the sum of the lengths X of all code marks of the n-digit pseudo random coding from which it is derived. In that case, exclusively individual code marks with the length 8 and code marks of the length 2 X arise in the single-track, combined code mark pattern according to the invention. Consequently, a code mark change takes place at the most after the length of 2 X and can be detected or scanned by means of the code reading device. A scanning signal, by which the sensors for detection of the single-track positional code are controlled in drive, is derived from the quasi-equidistant code mark changes. The reading then always takes place when the sensors are disposed completely in coincidence with the code marks to be read. The single-track code mark pattern is slender and accordingly requires only a small attachment area along the travel path. In addition, a single-track code carrier can be produced simply and economically. By merely one additional reading-off point of the code reading device, thus only n + 1 reading-off points, an unambiguous or absolute symbol pattern can be read off each time at the single track, according to the invention, of the combined code mark pattern. The code reading device with, in accordance with the invention, only n + 1 reading points is economic and is of relatively small construction by comparison with conventional code "eading devices for the same travel path extent and comparable resolution. For reading i ransiation oi Application amended tor national phase off the single-track, combined code mark pattern the sensors are arranged in movement direction on a line at a mutual spacing of Zk, whereby the code reading device is formed to be slender and thus can be movably arranged in space-saving manner laterally adjacent to the guide rail. In simple manner, even at start up and without travel of the lift cage, the absolute position thereof can be determined in that for each bit of the combined code mark pattern two sensors are arranged in travel direction at a spacing of half the code mark lengths. If one of the two sensors is disposed in the vicinity of a code mark change and delivers a sensor voltage of approximately the value zero, then the respective other sensor is, with certainty, disposed in coincidence with a code mark and delivers reliable information. The first sensors and the second sensors are, for absolute reading, in each instance combined into respective a sensor group. From the two interengaging sensor groups offset by half the code mark length, alternately always only the output signals of the sensors of one of the two sensor groups are selected for reading-off and evaluation. The switching over to the respective correct one of the two sensor groups is carried out by way of determination of the position of the transition between two different code marks and the two sensor groups by the scanning signal. In the case of use of the single-track, combined coding according to the invention in a magnetic measuring system the suppression of small magnetic poles by adjacent large magnetic poles, i.e. the so-termed inter-symbol interference, is reduced. This has a positive effect on the reading reliability in the case of a greater spacing of the code reading device from the code mark pattern. The spacing of the code reading device from the combined code mark pattern can thus be selected to be larger in the case of a larger magnetic measuring system. The measuring system is thus less susceptible to dirtying of the code carrier and occurring movements of the code reading device relative to the code mark pattern in a direction perpendicular to the reading or travel direction of the cage. The uniform length of the code marks additionally enables a quick evaluation by economic components operating in parallel. In a preferred embodiment, as a magnetic measuring system simple and economic Hall sensors are exclusively used for scanning the linear position code. Equally, Hall sensors of an interpolation device serve for determining the position of the transition between two different code marks - the zero transition of the magnetic field - relative to the sensor strip. Translation of Application amended for national phase The interpolation device is arranged in the travel direction over a region with a length greater than the length of two code marks 2k. Spacing between these Hall sensors is smaller than the length X of one code mark. Moreover, in a particularly preferred development of the invention it is proposed to use, additionally to the Hall sensors, an MR sensor by which the coding according to the invention is scanned and thus the resolution relative to previous absolute single-track systems is substantially increased. By virtue of the described characteristics, a combined code mark pattern with magnetic code marks externally forms a magnetic field with a path which is composed of approximately sinusoidal half-waves. These half-waves each have the length X of one code mark or the length 2X of two code marks. When scanning with an appropriate MR sensor, there can be produced, by arc-tangent interpolation of the sensor voltages, a high-resolution position value which in each instance is travel-proportional within a pole. In combination with the absolute position value with the resolution of a code mark length, a high-resolution absolute position results. A particularly reliable measuring system for determining the absolute cage position can be obtained if the code reading device for scanning the position code is constructed, inclusive of the evaluating unit, in redundant manner. The second code reading device is in that case constructed to be basically the same as the first code reading device and differs only by an arrangement of the intermediate reading unit and the fine interpolation in this sequence behind - in travel direction - the position code reading unit. The sensor pairs of the two position code reading devices are arranged in a line, which is parallel to the direction of reading, to be offset relative to one another by a code mark length X and to interengage. The code reading device is of compact construction and is longer than a measuring system of non-redundant construction merely by the interpolation device and the fine interpolation device. An own evaluating unit is associated with each of the two code reading devices, so that the output signals of the sensors of the two code reading devices are evaluated independently of one another and are available for the control of the lift. The redundant construction of the single-track measuring system additionally fulfils applicable safety requirements in the lift industry and thus offers the possibility of replacing previous mechanically executed safety devices by electrical safety devices. Moreover, it is i ransianon 01 Application amended for national phase the basis, together with a respective storey sensor for each of the two measuring systems, of a comprehensive shaft information system which is illustrated schematically in Fig. 7. One of the storey sensors is associated with each evaluating unit. The storey sensors are moved in the shaft together with the lift cage in order to detect position markings arranged in the shaft at each storey level. These signals are processed together with the output signals of safety devices, which are similarly provided in redundant manner, in common with the positional information and serve for control of the lift installation. Further features and advantages of the invention are evident from the following description of a preferred embodiment with reference to the accompanying drawing, in which: Fig. 1 schematically shows a lift installation with a device for determining the position of a lift cage; Fig. 2 schematically shows the construction of a first embodiment of the invention; Fig. 3 shows the sequence of arrangement of the individual bits in the combined code mark pattern; zig. 4 shows a second embodiment of the code reading sensor system; rig. 5 shows a course of the output signal of the interpolation device; rig. 6 shows the course of the output signal of an MR angle sensor of the fine interpolation in scanning of the magnetic field course over the coded magnetic strip; :ig. 6 shows a second redundant embodiment of the measuring system according to the invention and :ig. 7 shows a redundant construction of the signal-track measuring system as the basis of a comprehensive shaft information system. n the lift - which is schematically illustrated in Fig. 1 - with a lift shaft 1, a lift cage 2 and a ;ounterweight 3 are suspended at several support cables, of which a single support cable Translation of Application amended for national phase 4 is illustrated here as representative. The support cables run over a deflecting roller 5 and are guided over a driven drive pulley 6. The drive pulley 6 transmits the drive forces of a drive motor (not illustrated here) to the support cable 4, which is driven by the motor, for raising and lowering the counterweight 3 and the lift cage 2 along a guide rail 7. Guide shoes 9 fixedly connected with the lift cage 2 serve, in the travel direction 8, for guidance of the lift cage 2 at the guide rail 7 in a direction perpendicular to the travel direction 8. A magnetic strip 10 is mounted in stationary location at the guide rail 7 along the entire travel path of the lift cage 2 and parallel to the travel direction 8 of the lift cage 2. The magnetic strip 10 serves as a carrier for a single-track, combined code mark pattern according to the invention, which pattern represents the numerical codes of absolute positions of the lift cage 2 in the shaft 1 in relation to a zero point. A code reading device 12 is fixedly mounted on the lift cage 2 in travel direction 8. It essentially consists of a sensor block 13 which carries the code reading sensor system 11 and which is mounted by a mount 14 to be displaceable perpendicularly to the travel direction 8. A roller guide 15 guides the sensor block 13 at the guide rail 7 when the code reading device 12 is moved together with the lift cage 2. The same arrangement is also possible laterally or below at the lift cage 2. The code reading device 12 transfers the read-off coded information by way of connecting lines 16 to an evaluating unit 17. The evaluating unit 17 translates the read-off coded information into an absolute position statement, which is comprehensible for the lift control 18 and expressed in binary terms, before it is passed on by way of a depending cable 19 to the lift control 18, for example for the positioning of the lift cage 2. Fig. 2 schematically shows a first embodiment of the invention with a magnetic measuring system. A magnetic strip 10 with a single-track, combined code mark pattern 20 is mounted on a section of the guide rail 7. The code marks 21 are symbolised by equal-length rectangular sections, which are arranged in a track in the longitudinal direction of the magnetic strip 10 and which each have a length of X = 4 mm and are magnetised either as a magnetic north pole 22 or as a magnetic south pole 23. The individual north poles 22 and south poles 23 form external correspondingly oriented magnetic fields. In each instance, two mutually adjacent code marks 12 define a so-termed bit of the coding. If a north pole 22 is disposed in front of a south pole 23 in travel direction 8, then the value "0" is associated with this bit, whilst the value "1" is associated with a south/north Translation of Application amended for national phase transition. This form of weighting, which is defined by way of state changes, of the bits is known as a so-termed Manchester coding. For clarification, the corresponding binary numbers or bits are recorded in Fig. 2 above the individual pole transitions 24. The sequence of arrangement of the individual bits in the combined code mark pattern 20 is shown in Fig. 3. There, too, the individual pole transitions 24 are replaced by the respective corresponding bits of the coding. The coding according to the invention is built-up from a binary pseudo-random sequence 25 which is known per se and which is combined with its inverted counterpart 26. A pseudo-random sequence consists of bit sequences, which are arranged gaplessly one after the other, with n binary digits. On each movement forward by one bit in the binary pseudo-random sequence, then, as is known, a new n-digit binary bit sequence arises each time. Such a sequence n of bits disposed one after the other is termed code word in the following. The code words of a binary pseudo-random coding can, as is known, be produced with the help of a linear feedback shift register. The number of digits of the shift register in that case corresponds with the number of digits of the binary bit sequence or of the code word. In general, in an m bit pseudo-random coding, n = xexp (m) different code words can be differentiated, wherein x is the significance of the code word number and m is the number of digits or bits of the code word. The greatest number which can be represented results at N = xexp (m) - 1. The greater the number of bits, the more code words can be differentiated from one another. The embodiment of the invention illustrated in Fig. 3 is based on a pseudo-random sequence 25 of code words 27 with n = 17 digits. It is 2exp (17) - 1 bits long and consequently consists in total of n = 2exp (17) = 131,072 different code words 27. According to the invention, in the travel direction 8 of the described pseudo-random sequence 25 a bit with the significance "1" is inserted after each bit with the significance "0", and a "0" bit of the inverse pseudo-random sequence is inserted after each "1" bit. Consequently, a bit change takes place in the single-track, combined code mark pattern 20 at the latest after two bits. According to Fig. 3 this appears on the magnetic strip 10 in that only magnetic poles 22, 23 in the length 8 = 4 mm and the double length L = 2k = 8 mm are present and that a transition 24 from a north pole 22 to a south pole 23 or conversely occurs at the most after L = 2X- 8 mm. Translation of Application amended for national phase The n1 = 2exp (17) - 1 bits of the pseudo-random sequence 25 and the n2 = 2exp (17) -1 bits inverse thereto of the inverted counterpart 26 are summated to form the total nK = 2x (2exp (17) - 1) bits. This corresponds in the case of the code mark length X = 4 mm selected here to a geometric overall length of the single-track, combined code mark pattern 20 of Lmax = nK * 8 = 262,144 * 4 mm = 1048.576 m. Considered analytically, the combination yields a combined code mark pattern 20 in which in total NK = 2 (2exp (17) -1) - 36 = 2exp (18) - 2 - 36 = 262,106 code words now with, in each instance, eighteen digits are differentiated. Thus, the combination according to the invention yields, apart from doubling the number of bits or magnetic poles 22, 23, also a code digit gain. Consequently, with simultaneous scanning of each eighteen successive ones of the respective second bits of the combined code mark pattern 20 an unambiguous 18-digit read pattern 33 is thus read off without repetition of code words (Fig. 2). Correspondingly, the code reading sensor system 11 according to Fig. 2 for reading the eighteen-bit position code or code word 33 comprises a position code reading device 28 with eighteen sensor pairs 29, which is illustrated more specifically in Fig. 4. The sensor pairs 29 are arranged in travel direction 8 on a line at a spacing 20 which corresponds with the length 2X = 8 mm of two magnetic poles 22, 23. The two sensors 31, 31' of each of the sensor pairs 29 are separated by a mutual spacing 32 of the size of a half code mark length X/2 = 2 mm. If one of the two sensors 31, 31' is disposed in the vicinity of a magnetic pole change 24 and delivers a sensor voltage of approximately the value zero, then the respective other sensor 31, 31' is disposed with certainty in coincidence with one of the magnetic poles 22, 23 and delivers reliable information. All eighteen first sensors 31 are combined into a first sensor group and all eighteen second sensors 31' are combined into a second sensor group. Of the sensors 31 of the first sensor group and of the sensors 31* - which are offset by half the code mark length 7J2 = 2 mm in travel direction - of the second sensor group, alternately always only the output signals of the sensors of one of the two sensor groups for positional reading are selected and evaluated. The read-off pattern 33 of the position code reading device 28 of Fig. 2 is thus composed of eighteen simultaneously read bits, wherein, however, only each second bit of the combined code mark pattern 20 is read. The eighteen bits, which in described manner are simultaneously read off by the position code reading device 28, of a read-off pattern 33 are interpreted by the evaluating unit 17 in Translation of Application amended for national phase common as an eighteen-digit code word. An absolute position value 35 of the lift cage 2, which is issued as a binary number in correct sequence, is unambiguously associated with each of these n = 2 * (2exp (17) - 1) - 36 = 262,106 eighteen-digit code words of the combined code mark pattern 20 by way of a translation or decoding table stored in a fixed value store, here an EPROM. The resolution of the position code reading device 28 is here 4 mm, which corresponds with the length X of a code mark 21. The switching over to the respective correct one of the two sensor groups of the position code reading device 28 takes place by way of determination of the position of the pole transition 24 between a south pole 23 and a north pole 22 with the help of an interpolation device 36. The interpolation device 36 is arranged - in travel direction 8 - either in front of, as in Fig. 2, or behind, as here in Fig. 3, the position code reading device 28 at a spacing 37 of an integral number multiple of the length X = 4 mm of a code mark 21. The interpolation device 36 comprises a group of six Hall sensors SO to S5, which are placed one behind the other in the travel direction 8 at a spacing in each instance of X/2 = 2 mm, so that a spacing of 10 mm accordingly separates the first Hall sensor SO and the last Hall sensor S5. A zero position, i.e. a pole transition 24 of the above-described combined code mark pattern 20, is necessarily disposed in the region between the first Hall sensor SO and the last Hall sensor S5. The interpolation reading device 36 detects the quasi-equidistant pole transitions 24, which are created in accordance with the invention, or zero transitions of the magnetic field between two successive north poles 22 or south poles 23. An example of the output voltage of the six Hall sensors SO to S5 of the interpolation device 36 over the travel in travel direction 8 at millimetre intervals is illustrated in Fig. 5. Sufficiently known comparator circuits undertake the following comparisons of the voltages of individual sensors SO to S5, which are weighted as follows: U(S0) > 0 - > 0 U(S0)+1/3U(S1)>0 ->0 U(S0) + U(S1)>0 ->1 1/3U(S0) + U(S1)>0 ->1 U(S1)>0 ->1 Translation of Application amended for national phase U(S4) + 1/3 * U(S5) . , This gives, for the example illustrated in Fig. 5, the numerical sequence: 001111111111111111. It is thus expressed that a south pole 23 extends at the first interpolation sensor SO up to 0.5 mm therebehind. A north pole 22 is disposed from 1.0 mm to 9 mm behind the first interpolation sensor SO. The produced number sequence is decoded by way of a table, which for example is stored in a EPROM, into a three-digit binary number sequence which represents an interpolation value 46 (Fig. 2) with, in the case of the example, 3 mm. This is periodic with the code mark length X and indicates the polarity of the strip, calculated from the position of the first Hall sensor SO, in steps of, for example, 0.5 mm. The peak value bit 24 of this interpolation value 46 inverts at an interval of 2 mm and takes over, as scanning signal, that for the described switching over between the sensors 31 and 31' of the position code reading device 28. The three bits 24 of the interpolation value 46 are additionally included in the overall positional information 53. The voltages of the Hall sensors SO to S5 now only have to be compared with the threshold for OmT, for which purpose a comparator is provided for each of the six Hall sensors SO to S5 of the position code reading device 28. From the digital bits 24 resulting therefrom, the correct bits 24 are selected by way of a number of 2 to 1 multiplexers, which are controlled by the 2 mm bit 24 of the interpolation device 36. All that is still needed is a synchronisation pulse which can amount to several 100 kHz. The position value is actualised after a pulse cycle ( The single-track measuring system described to that extent can be built up with very economic components. It enables high travel speeds of more than 16 m/s. The measuring rate is dependent virtually only on the speed of the interface. The system resolution of this absolute single-track system is 0.5 mm, but can be substantially increased by additional use of a fine interpolation device 47. The fine interpolation unit 47 scans, additionally to the Hall sensors 31, 31 \ SO to S5, the combined code mark pattern 20 by a MR sensor 49 (MagnetoResistive = inductive resistance sensor). The MR angle sensor 49 is arranged at the code reading device 12 at a fixed spacing 1 = WXt which corresponds with a multiple of the length of a code mark 21, Translation of Application amended for national phase in front of the interpolation device 36 in the travel direction 8 in the case of the embodiment according to Fig. 2 and behind the interpolation device 36 in the travel direction 8 in the embodiment according to Fig. 4 and is moved together therewith relatively along the magnetic strip 10. In that case the MR angle sensor 49 detects the path of the magnetic field of the single-track, combined code mark pattern 20, which is composed of approximately sinusoidal half-waves of the length X = 4 mm or 2X = 8 mm of the magnetic fields formed by the north poles 22 and south poles 23. Fig. 6 shows the course of the output signal 48 of the MR angle sensor 49, which is used here, with the designation LK28 of the company IMO for scanning the half waves of the combined code mark pattern 20, recorded along the path in the travel direction 8. The sine-shaped and cosine-shaped output voltages of the MR sensor 49 are already arctangent interpolated by means of an interpolator chip or by software (not illustrated) in the microcontroller and so standardised that the minimum value 50 lies at 0 mm and the maximum value 51 at 4 mm. The output signal 48 yields high-resolution positional information which is travel-proportional within the length X = 4 mm of a north pole 22 or south pole 23 or 2X = 8 mm of two mutually adjacent magnetic poles of like sign. It can be inferred from the course of the output signal 48 of the MR angle sensor 49 that there is an 8 mm magnetic pole in the region 54 between 0 mm and 8 mm, and a 4 mm magnetic pole in the region 55 between 8 mm and 12 mm. This high-resolution positional information is further processed as follows: If the MR angle sensor 49 is disposed above a 4 mm magnetic pole then the interpolated positional information of the fine interpolation device 47 is taken over as high-resolution position value 52. If the MR sensor 49 is disposed above an 8 mm pole, then the interpolated positional information is multiplied by 2. If the value resulting therefrom is greater than the maximum value here predetermined by the length X = 4 mm of a magnetic pole, then the maximum value is subtracted. From this calculation rule there results a position value 52, which is periodic with the code mark length X, with a resolution in the order of magnitude of 50 :m, such as was previously obtained only from the incremental track of a conventional double-track system. Translation of Application amended for national phase The information whether the MR angle sensor 49 is disposed above a four mm or above an eight mm magnetic pole can be filed in the decoding table. Initially the code word 33 is determined by the position code reading device 28, and by way of the address - which is indicated by the code word 33 - of the decoding table not only the absolute position 35, but also the arrangement of the magnetic pole under the instantaneous position of the MR angle sensor 49 are read out. For calculation of the high-resolution overall position 53 the periodic high-resolution position values 52 determined by the fine interpolation device 47 and the absolute position value 35 of the resolution X = 4 mm determined by the position code reading device 28 are synchronised with one another in a microcontroller 40. This is possible in problem-free manner, since the absolute position 35 is available, as previously described, with a resolution of 0.5 mm. The calculation of the high-resolution overall position 53, which consists of in total twenty-four bits 24, of the lift cage 2 can be carried out very quickly, since only a few simple operations, for example comparisons, bit displacements, additions and subtractions, are necessary. The high travel speed possible by way of the coding according to the invention and the position code reading device 28 is not prejudiced by the fine interpolation device 47 if an interpolator chip with parallel output of the interpolated positional information is used and if the high-resolution position value 52 is intermediately stored, controlled by the synchronisation pulse, synchronously with the absolute position value 35. The distortions, which are recognisable in Fig. 6, of the course 48 of the interpolated position value obtained by fine interpolation can be undistorted by an undistorting table respectively for four and eight millimetre magnetic poles, whereby accuracy is substantially improved. This is possible because the distortions of magnetic poles of like length X or 2Xare closely similar at all positions of the combined code mark pattern 20. In Fig. 7 there is illustrated an embodiment of the invention in which the code reading sensor system 11 is constructed in redundant manner. The second code reading sensor system 1V is constructed in basically the same manner as the code reading sensor system 11 in the previously described first example of embodiment according to Fig. 4. By i ransianon 01 Application amended tor national phase contrast to the first embodiment of the code reading sensor system 11, in the case of the second code reading sensor system 11' the interpolation device 36' and the fine interpolation device 47' are arranged in this sequence in the travel direction 8 in front of the position code reading device 28. The second code reading sensor system 11' is placed in mirror symmetry relative to the first code reading sensor system 11, wherein the sensor pairs 29, 29' of the two position code reading devices 28, 28* interengage in a line, parallel to the travel/reading direction 8 and are offset relative to one another by a code mark length A= 4 mm. In this position the eighteen sensor pairs 29' of the second position code reading device 29 detect a read-off pattern 33 of eighteen of the respective first bits of the combined code mark pattern 20. As Fig. 8 shows, an own evaluating unit 17, 17' is associated with each of the two code reading sensor systems 11, 1V, so that the output signals of the sensors of the two code reading sensor systems 11, 1V are evaluated independently of one another, and two high-resolution values - which are determined independently of one another - of the overall position 53, 53 are available as a binary number with twenty-four digits for control of the lift. A comprehensive shaft information system with numerous functions can thus be obtained, in co-operation with an additional lift sensor system, starting from the redundancy, which is created in accordance with the invention, of the absolute measuring system for determining the absolute cage position. Examples of such functions, which proceed from determination of the absolute cage position, of a shaft information system are: the shaft end deceleration, shaft end limitation, storey recognition, level compensation, door bridging over as well as the most diverse travel regulations and much more. Fig. 7 shows a construction, in the redundant manner, of the single-track measuring system as the basis of a shaft information system. The redundant construction of the single-track measuring system is, together with a respective storey sensor 41, 41', the basis of a comprehensive shaft information system schematically illustrated in Fig. 7. One of the storey sensors 41, 41' is associated with Translation of Application amended for national phase each evaluating unit 17, 17'. The storey sensors 41, 41' are moved in the shaft together with the lift cage 2 in order to detect position markings 42, 42' arranged in the shaft 1 at each storey level. The signals of the storey sensors 41, 41' are processed together with the output signals of safety devices 43, 43\ which are similarly provided in redundant form, in common with the positional information 53 and serve for control of the lift. The length code mark pattern 20 of the magnetic strip 10 is, in this embodiment, represented by differently poled magnetised sections and is read off by means of sensors 31, 31\ SO to S6, which are sensitive to magnetic field, of the code reading device 12. Fundamentally, other physical principles for representation of the length coding are also conceivable. Thus, the code marks can also have different dielectric numbers, which are read by sensors detecting capacitive effects. Moreover, a reflective code mark pattern is possible in which, depending on the respective significance of the individual code marks, a greater or lesser amount of light is reflected from an illuminating device to reflected-light barriers as sensors. The invention enables the use of economic Hall sensors for reading the position code. In principle, however, a realisation with more costly induction transmitters, i.e. so-termed GMR sensors or magnetoresistive sensors detecting magnetic field direction, i.e. so-termed MR sensors, is also possible. Of each of these sensors, several individual sensors and/or a group of different sensors can be present in combination with one another at a code reading device. [P1317 16 Translation of Application amended for national phase CLAIMS: 1. Lift installation with a length measuring system for determining a cage position of a lift cage (2) movable along at least one guide rail (7), a code mark pattern (20) mounted near the lift cage and parallel to the travel direction (8), a code reading device (12), which is mounted on the lift cage, for contactless scanning of the code mark pattern and an evaluating unit (17) for evaluating scanned code mark patterns, characterised in that n successive code marks (21) of the code mark pattern form a code word (27), that code words are unambiguously arranged in an n-digit pseudo random sequence of different code words, that the code words form a single-track code mark pattern and that a scanned code word represents an absolute cage position (35). 2. Lift installation according to claim 1, characterised in that the code marks form magnetic poles and that the code reading device comprises Hall sensors (31, 31 \ S0-S5). 3. Lift installation according to claim 1 or 2, characterised in that the code reading device comprises several sensors for simultaneous scanning of the code marks of a code word. 4. Lift installation according to one of claims 1 to 3, characterised in that the code reading device comprises several sensors (S0-S5) for detection of code mark transitions, which in travel direction are arranged over a region with a length greater than the length (2k) of two code marks at a spacing smaller than the length of one code mark {k). 5. Lift installation according to one of claims 1 to 4, characterised in that the code reading device detects at least one transition (24) between code marks. 6. Lift installation according to one of claims 3 to 5, characterised in that a comparator compares a voltage of the sensors with a threshold. 7. Lift installation according to claim 5, characterised in that the resolution of the absolute cage position by scanning of a code word corresponds with the length of a code mark and/or that the resolution of the absolute cage position by detection of a transition (24) between code marks amounts to 0.5 mm. Translation of Application amended for national phase 8. Lift installation according to one of claims 1 to 7, characterised in that at least one storey sensor (41, 41') is mounted at the lift cage and detects position markings (42, 42') mounted at storey level and that a control evaluates detected position markings by scanned code words. 9. Lift installation according to one of claims 1 to 8, characterised in that the code reading device is constructed in redundant manner. 10. Lift installation according to one of claims 1 to, 9, characterised in that the code mark pattern is coded in Manchester coding, wherein each code mark is combined with an inverted code mark adjoining this and/or that the code mark pattern is mounted at the guide rail (7) and/or that the sensors are arranged in a line parallel to the travel direction. 11. Lift installation according to claim 2, characterised in that the code reading device comprises a fine interpolation unit (47) which detects the course of the magnetic field of the code mark pattern, which interpolates the course of the magnetic field of the code mark pattern in arc-tangential manner and which produces a high-resolution position value periodic with the code mark length. 12. Lift installation according to claim 1, characterised in that the code marks have different dielectric constants and that the code reading device comprises sensors detecting capacitive effects. A lift installation with a length measuring system substantially as herein described with reference to the accompanying drawings. A

Full Text

U 1J1 f Translation of Application amended for national phase
Lift installation with a measuring system for determining absolute cage position
The invention relates to a lift installation with a measuring system for determining the absolute cage position of a lift cage movable along at least one guide rail, according to the definition of the patent claims.
In lifts, the positional information is applied in coded form in stationary position along the entire travel path of the lift cage and is read off in coded form by means of a code reading device and passed on to an evaluating unit. The evaluating unit prepares the read-off coded positional information to be comprehensible by a control and derives therefrom data signals which are passed on to the lift control as so-termed shaft data.
An absolute measuring system with high resolution for determination of the relative position of two parts movable relative to one another is known from DE 42 09 629 A1. In hitherto conventional manner an absolute code mark pattern in the form of a gapless sequence of equal-length code marks of a pseudo random coding are formed there at a first part in a first track and an incremental code symbol pattern is formed there in a second track parallel thereto. In the absolute code mark pattern, any n successive code marks in each instance represent a code word. Each of these code words is present only once in the entire code mark pattern. A code reading device, which can detect n successive code marks all at once in movement direction and in that case scans the incremental code symbol pattern, is provided at a second part movable relative to the first part. If the code reading device is moved along the first part by one code mark position of the absolute code mark pattern, a new n-digit binary code word is read.
In this known device each code word of the absolute code mark pattern defines a specific position of the two parts relative to one another. The length, which is measured in the direction of movement or reading, of the individual code marks and the number of the maximum possible code words establish the maximum length of the measuring path able to be addressed by code words. The resolution capability by which the relative position, i.e. the so-termed position code, expressed in the pseudo random code can be measured depends on the length of each individual code mark. The smaller the length of the code marks, the more accurate the positioning can be. However, reading-off becomes noticeably more difficult with decreasing lengths of the code marks, particularly in the case of high relative speeds.

I ransiation ot Application amended for national phase
In the case of use of such an absolute length measuring system for determining the position of a lift cage, such as, for example, the lift known from German Utility Model G 92 10 996.9t the entire travel path in the travel direction of the lift cage is to be addressed in gapless manner with coded position details, i.e. the code words of the pseudo random coding. The maximum of the measuring or travel path extent is then, however, limited by the sum of the length of all code marks. A pseudo random coding with multi-digit code words and/or code marks of greater length accordingly has to be provided for long travel paths. However, multi-digit code words necessitate correspondingly complicated code reading devices and evaluating units and this is connected with high costs. With increasing length of the individual code marks, however, the resolution capability diminishes.
In order to avoid errors in reading, the absolute code mark pattern and the incremental code symbol pattern are to be represented in their relative position exactly aligned with one another. This makes the production of a double-track code carrier expensive and moreover necessitates a time-consumingly precise mounting. In addition, the code reading device, in particular, of a double-track absolute position measuring system is of large construction, which is undesirable with respect to the limited shaft cross-sectional area available. Furthermore, the travel speed in the case of double-track measuring systems is limited, which is felt to be limiting especially for lifts with large conveying weights.
The object of the invention is to indicate a lift of the kind described in the introduction with a measuring system for determining the absolute position of the lift cage, which enables a nigh-resolution in the position recognition over a long travel path of the lift cage with smallest possible expenditure.
\ccording to the invention this object is met by a lift with an absolute position measuring system with the features of claim 1, which is distinguished particularly by the fact that the absolute code mark pattern and the incremental code symbol pattern are represented as a single-track, combined code mark pattern of n-digit pseudo random sequence in Manchester coding and the code reading device comprises sensors for scanning n + 1 successive code marks, wherein each second code mark of the single-track, combined ■nark pattern is scanned.

Translation of Application amended for national phase
The essence of the invention consists in a single-track coding for an absolute length measuring system in which starting from a binary n-digit pseudo random sequence, by which T - 1 different position values are coded, a 1 is inserted behind each 0 and a 0 is inserted behind each 1. The thereby-obtained sequence according to the invention with double length represents quasi a combination of the n-digit pseudo random coding and a Manchester coding. So that all code words arising in the combined code mark pattern according to the invention differ from one another, n + 1 code marks of the respective second code marks of the combined code mark pattern have to be scanned.
The advantages of absolute single-track systems are combined, by the coding according to the invention, with the advantage of the high resolution of the absolute double-track or multiple-track systems.
By the combined coding according to the invention there can be represented, by an n-digit pseudo random coding with unchanged resolution, a measuring path twice as long as that corresponding with the sum of the lengths X of all code marks of the n-digit pseudo random coding from which it is derived. In that case, exclusively individual code marks with the length 8 and code marks of the length 2 X arise in the single-track, combined code mark pattern according to the invention. Consequently, a code mark change takes place at the most after the length of 2 X and can be detected or scanned by means of the code reading device. A scanning signal, by which the sensors for detection of the single-track positional code are controlled in drive, is derived from the quasi-equidistant code mark changes. The reading then always takes place when the sensors are disposed completely in coincidence with the code marks to be read. The single-track code mark pattern is slender and accordingly requires only a small attachment area along the travel path. In addition, a single-track code carrier can be produced simply and economically.
By merely one additional reading-off point of the code reading device, thus only n + 1 reading-off points, an unambiguous or absolute symbol pattern can be read off each time at the single track, according to the invention, of the combined code mark pattern.
The code reading device with, in accordance with the invention, only n + 1 reading points is economic and is of relatively small construction by comparison with conventional code "eading devices for the same travel path extent and comparable resolution. For reading

i ransiation oi Application amended tor national phase
off the single-track, combined code mark pattern the sensors are arranged in movement direction on a line at a mutual spacing of Zk, whereby the code reading device is formed to be slender and thus can be movably arranged in space-saving manner laterally adjacent to the guide rail.
In simple manner, even at start up and without travel of the lift cage, the absolute position thereof can be determined in that for each bit of the combined code mark pattern two sensors are arranged in travel direction at a spacing of half the code mark lengths. If one of the two sensors is disposed in the vicinity of a code mark change and delivers a sensor voltage of approximately the value zero, then the respective other sensor is, with certainty, disposed in coincidence with a code mark and delivers reliable information. The first sensors and the second sensors are, for absolute reading, in each instance combined into respective a sensor group. From the two interengaging sensor groups offset by half the code mark length, alternately always only the output signals of the sensors of one of the two sensor groups are selected for reading-off and evaluation. The switching over to the respective correct one of the two sensor groups is carried out by way of determination of the position of the transition between two different code marks and the two sensor groups by the scanning signal.
In the case of use of the single-track, combined coding according to the invention in a magnetic measuring system the suppression of small magnetic poles by adjacent large magnetic poles, i.e. the so-termed inter-symbol interference, is reduced. This has a positive effect on the reading reliability in the case of a greater spacing of the code reading device from the code mark pattern. The spacing of the code reading device from the combined code mark pattern can thus be selected to be larger in the case of a larger magnetic measuring system. The measuring system is thus less susceptible to dirtying of the code carrier and occurring movements of the code reading device relative to the code mark pattern in a direction perpendicular to the reading or travel direction of the cage. The uniform length of the code marks additionally enables a quick evaluation by economic components operating in parallel.
In a preferred embodiment, as a magnetic measuring system simple and economic Hall sensors are exclusively used for scanning the linear position code. Equally, Hall sensors of an interpolation device serve for determining the position of the transition between two different code marks - the zero transition of the magnetic field - relative to the sensor strip.

Translation of Application amended for national phase
The interpolation device is arranged in the travel direction over a region with a length greater than the length of two code marks 2k. Spacing between these Hall sensors is smaller than the length X of one code mark.
Moreover, in a particularly preferred development of the invention it is proposed to use, additionally to the Hall sensors, an MR sensor by which the coding according to the invention is scanned and thus the resolution relative to previous absolute single-track systems is substantially increased. By virtue of the described characteristics, a combined code mark pattern with magnetic code marks externally forms a magnetic field with a path which is composed of approximately sinusoidal half-waves. These half-waves each have the length X of one code mark or the length 2X of two code marks. When scanning with an appropriate MR sensor, there can be produced, by arc-tangent interpolation of the sensor voltages, a high-resolution position value which in each instance is travel-proportional within a pole. In combination with the absolute position value with the resolution of a code mark length, a high-resolution absolute position results.
A particularly reliable measuring system for determining the absolute cage position can be obtained if the code reading device for scanning the position code is constructed, inclusive of the evaluating unit, in redundant manner. The second code reading device is in that case constructed to be basically the same as the first code reading device and differs only by an arrangement of the intermediate reading unit and the fine interpolation in this sequence behind - in travel direction - the position code reading unit. The sensor pairs of the two position code reading devices are arranged in a line, which is parallel to the direction of reading, to be offset relative to one another by a code mark length X and to interengage. The code reading device is of compact construction and is longer than a measuring system of non-redundant construction merely by the interpolation device and the fine interpolation device.
An own evaluating unit is associated with each of the two code reading devices, so that the output signals of the sensors of the two code reading devices are evaluated independently of one another and are available for the control of the lift.
The redundant construction of the single-track measuring system additionally fulfils applicable safety requirements in the lift industry and thus offers the possibility of replacing previous mechanically executed safety devices by electrical safety devices. Moreover, it is

i ransianon 01 Application amended for national phase
the basis, together with a respective storey sensor for each of the two measuring systems, of a comprehensive shaft information system which is illustrated schematically in Fig. 7. One of the storey sensors is associated with each evaluating unit. The storey sensors are moved in the shaft together with the lift cage in order to detect position markings arranged in the shaft at each storey level. These signals are processed together with the output signals of safety devices, which are similarly provided in redundant manner, in common with the positional information and serve for control of the lift installation.
Further features and advantages of the invention are evident from the following description of a preferred embodiment with reference to the accompanying drawing, in which:
Fig. 1 schematically shows a lift installation with a device for determining the
position of a lift cage;
Fig. 2 schematically shows the construction of a first embodiment of the invention;
Fig. 3 shows the sequence of arrangement of the individual bits in the combined
code mark pattern;
zig. 4 shows a second embodiment of the code reading sensor system;
rig. 5 shows a course of the output signal of the interpolation device;
rig. 6 shows the course of the output signal of an MR angle sensor of the fine
interpolation in scanning of the magnetic field course over the coded magnetic strip;
:ig. 6 shows a second redundant embodiment of the measuring system according
to the invention and
:ig. 7 shows a redundant construction of the signal-track measuring system as
the basis of a comprehensive shaft information system.
n the lift - which is schematically illustrated in Fig. 1 - with a lift shaft 1, a lift cage 2 and a ;ounterweight 3 are suspended at several support cables, of which a single support cable

Translation of Application amended for national phase
4 is illustrated here as representative. The support cables run over a deflecting roller 5 and are guided over a driven drive pulley 6. The drive pulley 6 transmits the drive forces of a drive motor (not illustrated here) to the support cable 4, which is driven by the motor, for raising and lowering the counterweight 3 and the lift cage 2 along a guide rail 7. Guide shoes 9 fixedly connected with the lift cage 2 serve, in the travel direction 8, for guidance of the lift cage 2 at the guide rail 7 in a direction perpendicular to the travel direction 8. A magnetic strip 10 is mounted in stationary location at the guide rail 7 along the entire travel path of the lift cage 2 and parallel to the travel direction 8 of the lift cage 2. The magnetic strip 10 serves as a carrier for a single-track, combined code mark pattern according to the invention, which pattern represents the numerical codes of absolute positions of the lift cage 2 in the shaft 1 in relation to a zero point.
A code reading device 12 is fixedly mounted on the lift cage 2 in travel direction 8. It essentially consists of a sensor block 13 which carries the code reading sensor system 11 and which is mounted by a mount 14 to be displaceable perpendicularly to the travel direction 8. A roller guide 15 guides the sensor block 13 at the guide rail 7 when the code reading device 12 is moved together with the lift cage 2. The same arrangement is also possible laterally or below at the lift cage 2.
The code reading device 12 transfers the read-off coded information by way of connecting lines 16 to an evaluating unit 17. The evaluating unit 17 translates the read-off coded information into an absolute position statement, which is comprehensible for the lift control 18 and expressed in binary terms, before it is passed on by way of a depending cable 19 to the lift control 18, for example for the positioning of the lift cage 2.
Fig. 2 schematically shows a first embodiment of the invention with a magnetic measuring system. A magnetic strip 10 with a single-track, combined code mark pattern 20 is mounted on a section of the guide rail 7. The code marks 21 are symbolised by equal-length rectangular sections, which are arranged in a track in the longitudinal direction of the magnetic strip 10 and which each have a length of X = 4 mm and are magnetised either as a magnetic north pole 22 or as a magnetic south pole 23. The individual north poles 22 and south poles 23 form external correspondingly oriented magnetic fields. In each instance, two mutually adjacent code marks 12 define a so-termed bit of the coding. If a north pole 22 is disposed in front of a south pole 23 in travel direction 8, then the value "0" is associated with this bit, whilst the value "1" is associated with a south/north

Translation of Application amended for national phase
transition. This form of weighting, which is defined by way of state changes, of the bits is known as a so-termed Manchester coding. For clarification, the corresponding binary numbers or bits are recorded in Fig. 2 above the individual pole transitions 24.
The sequence of arrangement of the individual bits in the combined code mark pattern 20 is shown in Fig. 3. There, too, the individual pole transitions 24 are replaced by the respective corresponding bits of the coding. The coding according to the invention is built-up from a binary pseudo-random sequence 25 which is known per se and which is combined with its inverted counterpart 26.
A pseudo-random sequence consists of bit sequences, which are arranged gaplessly one after the other, with n binary digits. On each movement forward by one bit in the binary pseudo-random sequence, then, as is known, a new n-digit binary bit sequence arises each time. Such a sequence n of bits disposed one after the other is termed code word in the following. The code words of a binary pseudo-random coding can, as is known, be produced with the help of a linear feedback shift register. The number of digits of the shift register in that case corresponds with the number of digits of the binary bit sequence or of the code word. In general, in an m bit pseudo-random coding, n = xexp (m) different code words can be differentiated, wherein x is the significance of the code word number and m is the number of digits or bits of the code word. The greatest number which can be represented results at N = xexp (m) - 1. The greater the number of bits, the more code words can be differentiated from one another.
The embodiment of the invention illustrated in Fig. 3 is based on a pseudo-random sequence 25 of code words 27 with n = 17 digits. It is 2exp (17) - 1 bits long and consequently consists in total of n = 2exp (17) = 131,072 different code words 27. According to the invention, in the travel direction 8 of the described pseudo-random sequence 25 a bit with the significance "1" is inserted after each bit with the significance "0", and a "0" bit of the inverse pseudo-random sequence is inserted after each "1" bit. Consequently, a bit change takes place in the single-track, combined code mark pattern 20 at the latest after two bits. According to Fig. 3 this appears on the magnetic strip 10 in that only magnetic poles 22, 23 in the length 8 = 4 mm and the double length L = 2k = 8 mm are present and that a transition 24 from a north pole 22 to a south pole 23 or conversely occurs at the most after L = 2X- 8 mm.

Translation of Application amended for national phase
The n1 = 2exp (17) - 1 bits of the pseudo-random sequence 25 and the n2 = 2exp (17) -1 bits inverse thereto of the inverted counterpart 26 are summated to form the total nK = 2x (2exp (17) - 1) bits. This corresponds in the case of the code mark length X = 4 mm selected here to a geometric overall length of the single-track, combined code mark pattern 20 of Lmax = nK * 8 = 262,144 * 4 mm = 1048.576 m.
Considered analytically, the combination yields a combined code mark pattern 20 in which in total NK = 2 (2exp (17) -1) - 36 = 2exp (18) - 2 - 36 = 262,106 code words now with, in each instance, eighteen digits are differentiated. Thus, the combination according to the invention yields, apart from doubling the number of bits or magnetic poles 22, 23, also a code digit gain. Consequently, with simultaneous scanning of each eighteen successive ones of the respective second bits of the combined code mark pattern 20 an unambiguous 18-digit read pattern 33 is thus read off without repetition of code words (Fig. 2).
Correspondingly, the code reading sensor system 11 according to Fig. 2 for reading the eighteen-bit position code or code word 33 comprises a position code reading device 28 with eighteen sensor pairs 29, which is illustrated more specifically in Fig. 4. The sensor pairs 29 are arranged in travel direction 8 on a line at a spacing 20 which corresponds with the length 2X = 8 mm of two magnetic poles 22, 23. The two sensors 31, 31' of each of the sensor pairs 29 are separated by a mutual spacing 32 of the size of a half code mark length X/2 = 2 mm. If one of the two sensors 31, 31' is disposed in the vicinity of a magnetic pole change 24 and delivers a sensor voltage of approximately the value zero, then the respective other sensor 31, 31' is disposed with certainty in coincidence with one of the magnetic poles 22, 23 and delivers reliable information. All eighteen first sensors 31 are combined into a first sensor group and all eighteen second sensors 31' are combined into a second sensor group. Of the sensors 31 of the first sensor group and of the sensors 31* - which are offset by half the code mark length 7J2 = 2 mm in travel direction - of the second sensor group, alternately always only the output signals of the sensors of one of the two sensor groups for positional reading are selected and evaluated. The read-off pattern 33 of the position code reading device 28 of Fig. 2 is thus composed of eighteen simultaneously read bits, wherein, however, only each second bit of the combined code mark pattern 20 is read.
The eighteen bits, which in described manner are simultaneously read off by the position code reading device 28, of a read-off pattern 33 are interpreted by the evaluating unit 17 in

Translation of Application amended for national phase
common as an eighteen-digit code word. An absolute position value 35 of the lift cage 2, which is issued as a binary number in correct sequence, is unambiguously associated with each of these n = 2 * (2exp (17) - 1) - 36 = 262,106 eighteen-digit code words of the combined code mark pattern 20 by way of a translation or decoding table stored in a fixed value store, here an EPROM. The resolution of the position code reading device 28 is here 4 mm, which corresponds with the length X of a code mark 21.
The switching over to the respective correct one of the two sensor groups of the position code reading device 28 takes place by way of determination of the position of the pole transition 24 between a south pole 23 and a north pole 22 with the help of an interpolation device 36. The interpolation device 36 is arranged - in travel direction 8 - either in front of, as in Fig. 2, or behind, as here in Fig. 3, the position code reading device 28 at a spacing 37 of an integral number multiple of the length X = 4 mm of a code mark 21. The interpolation device 36 comprises a group of six Hall sensors SO to S5, which are placed one behind the other in the travel direction 8 at a spacing in each instance of X/2 = 2 mm, so that a spacing of 10 mm accordingly separates the first Hall sensor SO and the last Hall sensor S5. A zero position, i.e. a pole transition 24 of the above-described combined code mark pattern 20, is necessarily disposed in the region between the first Hall sensor SO and the last Hall sensor S5. The interpolation reading device 36 detects the quasi-equidistant pole transitions 24, which are created in accordance with the invention, or zero transitions of the magnetic field between two successive north poles 22 or south poles 23.
An example of the output voltage of the six Hall sensors SO to S5 of the interpolation device 36 over the travel in travel direction 8 at millimetre intervals is illustrated in Fig. 5. Sufficiently known comparator circuits undertake the following comparisons of the voltages of individual sensors SO to S5, which are weighted as follows:
U(S0) > 0 - > 0
U(S0)+1/3*U(S1)>0 ->0
U(S0) + U(S1)>0 ->1
1/3*U(S0) + U(S1)>0 ->1
U(S1)>0 ->1

Translation of Application amended for national phase
U(S4) + 1/3 * U(S5) . ,
This gives, for the example illustrated in Fig. 5, the numerical sequence: 001111111111111111. It is thus expressed that a south pole 23 extends at the first interpolation sensor SO up to 0.5 mm therebehind. A north pole 22 is disposed from 1.0 mm to 9 mm behind the first interpolation sensor SO.
The produced number sequence is decoded by way of a table, which for example is stored in a EPROM, into a three-digit binary number sequence which represents an interpolation value 46 (Fig. 2) with, in the case of the example, 3 mm. This is periodic with the code mark length X and indicates the polarity of the strip, calculated from the position of the first Hall sensor SO, in steps of, for example, 0.5 mm. The peak value bit 24 of this interpolation value 46 inverts at an interval of 2 mm and takes over, as scanning signal, that for the described switching over between the sensors 31 and 31' of the position code reading device 28.
The three bits 24 of the interpolation value 46 are additionally included in the overall positional information 53. The voltages of the Hall sensors SO to S5 now only have to be compared with the threshold for OmT, for which purpose a comparator is provided for each of the six Hall sensors SO to S5 of the position code reading device 28. From the digital bits 24 resulting therefrom, the correct bits 24 are selected by way of a number of 2 to 1 multiplexers, which are controlled by the 2 mm bit 24 of the interpolation device 36. All that is still needed is a synchronisation pulse which can amount to several 100 kHz. The position value is actualised after a pulse cycle ( The single-track measuring system described to that extent can be built up with very economic components. It enables high travel speeds of more than 16 m/s. The measuring rate is dependent virtually only on the speed of the interface. The system resolution of this absolute single-track system is 0.5 mm, but can be substantially increased by additional use of a fine interpolation device 47.
The fine interpolation unit 47 scans, additionally to the Hall sensors 31, 31 \ SO to S5, the combined code mark pattern 20 by a MR sensor 49 (MagnetoResistive = inductive resistance sensor). The MR angle sensor 49 is arranged at the code reading device 12 at a fixed spacing 1 = WXt which corresponds with a multiple of the length of a code mark 21,

Translation of Application amended for national phase
in front of the interpolation device 36 in the travel direction 8 in the case of the embodiment according to Fig. 2 and behind the interpolation device 36 in the travel direction 8 in the embodiment according to Fig. 4 and is moved together therewith relatively along the magnetic strip 10. In that case the MR angle sensor 49 detects the path of the magnetic field of the single-track, combined code mark pattern 20, which is composed of approximately sinusoidal half-waves of the length X = 4 mm or 2X = 8 mm of the magnetic fields formed by the north poles 22 and south poles 23.
Fig. 6 shows the course of the output signal 48 of the MR angle sensor 49, which is used here, with the designation LK28 of the company IMO for scanning the half waves of the combined code mark pattern 20, recorded along the path in the travel direction 8. The sine-shaped and cosine-shaped output voltages of the MR sensor 49 are already arctangent interpolated by means of an interpolator chip or by software (not illustrated) in the microcontroller and so standardised that the minimum value 50 lies at 0 mm and the maximum value 51 at 4 mm. The output signal 48 yields high-resolution positional information which is travel-proportional within the length X = 4 mm of a north pole 22 or south pole 23 or 2X = 8 mm of two mutually adjacent magnetic poles of like sign.
It can be inferred from the course of the output signal 48 of the MR angle sensor 49 that there is an 8 mm magnetic pole in the region 54 between 0 mm and 8 mm, and a 4 mm magnetic pole in the region 55 between 8 mm and 12 mm.
This high-resolution positional information is further processed as follows:
If the MR angle sensor 49 is disposed above a 4 mm magnetic pole then the interpolated positional information of the fine interpolation device 47 is taken over as high-resolution position value 52. If the MR sensor 49 is disposed above an 8 mm pole, then the interpolated positional information is multiplied by 2. If the value resulting therefrom is greater than the maximum value here predetermined by the length X = 4 mm of a magnetic pole, then the maximum value is subtracted.
From this calculation rule there results a position value 52, which is periodic with the code mark length X, with a resolution in the order of magnitude of 50 :m, such as was previously obtained only from the incremental track of a conventional double-track system.

Translation of Application amended for national phase
The information whether the MR angle sensor 49 is disposed above a four mm or above an eight mm magnetic pole can be filed in the decoding table. Initially the code word 33 is determined by the position code reading device 28, and by way of the address - which is indicated by the code word 33 - of the decoding table not only the absolute position 35, but also the arrangement of the magnetic pole under the instantaneous position of the MR angle sensor 49 are read out.
For calculation of the high-resolution overall position 53 the periodic high-resolution position values 52 determined by the fine interpolation device 47 and the absolute position value 35 of the resolution X = 4 mm determined by the position code reading device 28 are synchronised with one another in a microcontroller 40. This is possible in problem-free manner, since the absolute position 35 is available, as previously described, with a resolution of 0.5 mm.
The calculation of the high-resolution overall position 53, which consists of in total twenty-four bits 24, of the lift cage 2 can be carried out very quickly, since only a few simple operations, for example comparisons, bit displacements, additions and subtractions, are necessary.
The high travel speed possible by way of the coding according to the invention and the position code reading device 28 is not prejudiced by the fine interpolation device 47 if an interpolator chip with parallel output of the interpolated positional information is used and if the high-resolution position value 52 is intermediately stored, controlled by the synchronisation pulse, synchronously with the absolute position value 35.
The distortions, which are recognisable in Fig. 6, of the course 48 of the interpolated position value obtained by fine interpolation can be undistorted by an undistorting table respectively for four and eight millimetre magnetic poles, whereby accuracy is substantially improved. This is possible because the distortions of magnetic poles of like length X or 2Xare closely similar at all positions of the combined code mark pattern 20.
In Fig. 7 there is illustrated an embodiment of the invention in which the code reading sensor system 11 is constructed in redundant manner. The second code reading sensor system 1V is constructed in basically the same manner as the code reading sensor system 11 in the previously described first example of embodiment according to Fig. 4. By

i ransianon 01 Application amended tor national phase
contrast to the first embodiment of the code reading sensor system 11, in the case of the second code reading sensor system 11' the interpolation device 36' and the fine interpolation device 47' are arranged in this sequence in the travel direction 8 in front of the position code reading device 28.
The second code reading sensor system 11' is placed in mirror symmetry relative to the first code reading sensor system 11, wherein the sensor pairs 29, 29' of the two position code reading devices 28, 28* interengage in a line, parallel to the travel/reading direction 8 and are offset relative to one another by a code mark length A= 4 mm. In this position the eighteen sensor pairs 29' of the second position code reading device 29 detect a read-off pattern 33 of eighteen of the respective first bits of the combined code mark pattern 20.
As Fig. 8 shows, an own evaluating unit 17, 17' is associated with each of the two code reading sensor systems 11, 1V, so that the output signals of the sensors of the two code reading sensor systems 11, 1V are evaluated independently of one another, and two high-resolution values - which are determined independently of one another - of the overall position 53, 53 are available as a binary number with twenty-four digits for control of the lift.
A comprehensive shaft information system with numerous functions can thus be obtained, in co-operation with an additional lift sensor system, starting from the redundancy, which is created in accordance with the invention, of the absolute measuring system for determining the absolute cage position.
Examples of such functions, which proceed from determination of the absolute cage position, of a shaft information system are: the shaft end deceleration, shaft end limitation, storey recognition, level compensation, door bridging over as well as the most diverse travel regulations and much more.
Fig. 7 shows a construction, in the redundant manner, of the single-track measuring system as the basis of a shaft information system.
The redundant construction of the single-track measuring system is, together with a respective storey sensor 41, 41', the basis of a comprehensive shaft information system schematically illustrated in Fig. 7. One of the storey sensors 41, 41' is associated with

Translation of Application amended for national phase
each evaluating unit 17, 17'. The storey sensors 41, 41' are moved in the shaft together with the lift cage 2 in order to detect position markings 42, 42' arranged in the shaft 1 at each storey level. The signals of the storey sensors 41, 41' are processed together with the output signals of safety devices 43, 43\ which are similarly provided in redundant form, in common with the positional information 53 and serve for control of the lift.
The length code mark pattern 20 of the magnetic strip 10 is, in this embodiment, represented by differently poled magnetised sections and is read off by means of sensors 31, 31\ SO to S6, which are sensitive to magnetic field, of the code reading device 12. Fundamentally, other physical principles for representation of the length coding are also conceivable. Thus, the code marks can also have different dielectric numbers, which are read by sensors detecting capacitive effects. Moreover, a reflective code mark pattern is possible in which, depending on the respective significance of the individual code marks, a greater or lesser amount of light is reflected from an illuminating device to reflected-light barriers as sensors.
The invention enables the use of economic Hall sensors for reading the position code. In principle, however, a realisation with more costly induction transmitters, i.e. so-termed GMR sensors or magnetoresistive sensors detecting magnetic field direction, i.e. so-termed MR sensors, is also possible. Of each of these sensors, several individual sensors and/or a group of different sensors can be present in combination with one another at a code reading device.

[P1317 16
Translation of Application amended for national phase
CLAIMS:
1. Lift installation with a length measuring system for determining a cage position of a lift cage (2) movable along at least one guide rail (7), a code mark pattern (20) mounted near the lift cage and parallel to the travel direction (8), a code reading device (12), which is mounted on the lift cage, for contactless scanning of the code mark pattern and an evaluating unit (17) for evaluating scanned code mark patterns, characterised in that n successive code marks (21) of the code mark pattern form a code word (27), that code words are unambiguously arranged in an n-digit pseudo random sequence of different code words, that the code words form a single-track code mark pattern and that a scanned code word represents an absolute cage position (35).
2. Lift installation according to claim 1, characterised in that the code marks form magnetic poles and that the code reading device comprises Hall sensors (31, 31 \ S0-S5).
3. Lift installation according to claim 1 or 2, characterised in that the code reading device comprises several sensors for simultaneous scanning of the code marks of a code word.
4. Lift installation according to one of claims 1 to 3, characterised in that the code reading device comprises several sensors (S0-S5) for detection of code mark transitions, which in travel direction are arranged over a region with a length greater than the length (2k) of two code marks at a spacing smaller than the length of one code mark {k).
5. Lift installation according to one of claims 1 to 4, characterised in that the code reading device detects at least one transition (24) between code marks.
6. Lift installation according to one of claims 3 to 5, characterised in that a comparator compares a voltage of the sensors with a threshold.
7. Lift installation according to claim 5, characterised in that the resolution of the absolute cage position by scanning of a code word corresponds with the length of a code mark and/or that the resolution of the absolute cage position by detection of a transition (24) between code marks amounts to 0.5 mm.

Translation of Application amended for national phase
8. Lift installation according to one of claims 1 to 7, characterised in that at least one storey sensor (41, 41') is mounted at the lift cage and detects position markings (42, 42') mounted at storey level and that a control evaluates detected position markings by scanned code words.
9. Lift installation according to one of claims 1 to 8, characterised in that the code reading device is constructed in redundant manner.
10. Lift installation according to one of claims 1 to, 9, characterised in that the code mark pattern is coded in Manchester coding, wherein each code mark is combined with an inverted code mark adjoining this and/or that the code mark pattern is mounted at the guide rail (7) and/or that the sensors are arranged in a line parallel to the travel direction.
11. Lift installation according to claim 2, characterised in that the code reading device comprises a fine interpolation unit (47) which detects the course of the magnetic field of the code mark pattern, which interpolates the course of the magnetic field of the code mark pattern in arc-tangential manner and which produces a high-resolution position value periodic with the code mark length.
12. Lift installation according to claim 1, characterised in that the code marks have different dielectric constants and that the code reading device comprises sensors detecting capacitive effects.

A lift installation with a length measuring system substantially as herein described with reference to the accompanying drawings.
A

Documents:

203-chenp-2004 abstract granted.pdf

203-chenp-2004 claims granted.pdf

203-chenp-2004 description (complete) granted.pdf

203-chenp-2004 drawings granted.pdf

203-chenp-2004-claims.pdf

203-chenp-2004-correspondnece-others.pdf

203-chenp-2004-correspondnece-po.pdf

203-chenp-2004-description(complete).pdf

203-chenp-2004-drawings.pdf

203-chenp-2004-form 1.pdf

203-chenp-2004-form 3.pdf

203-chenp-2004-form 5.pdf

203-chenp-2004-form18.pdf

203-chenp-2004-pct.pdf

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Patent Number

227463

Indian Patent Application Number

203/CHENP/2004

PG Journal Number

10/2009

Publication Date

06-Mar-2009

Grant Date

07-Jan-2009

Date of Filing

30-Jan-2004

Name of Patentee

INVENTIO AG

Applicant Address

SEESTRASSE 55, CH-6052 HERGISWIL

Inventors:

#	Inventor's Name	Inventor's Address
1	BIRRER, ERIC	HERTENSTEINSTRASSE 34, CH-6004 LUZERN
2	ESSINGER, HEIKO	IN DER BREITE 16, 787239 RIELASINGEN,
3	MULLER , FRANK	HEUNERSTRASSE 41, 44229 DORTMUND,

PCT International Classification Number

B66B 1/34

PCT International Application Number

PCT/CH02/00406

PCT International Filing date

2002-07-22

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	01810750.8	2001-07-31	EUROPEAN UNION