Title of Invention	AN INTRINSICALLY SAFE TELEPHONE EXCHANGE USEFUL FOR AREAS HAVING EXPLOSIVE ATMOSPHER
Abstract	An intrinsically safe telephone exchange useful for areas having explosive atmosphere which comprises an input block which consists of a decade counter (7), an intrinsically safe switch (8), a sample and hold circuit (9), a tristate buffer (10) and a main distribution frame (11), the said input block being connected to a central processor(6) through parallel port (18), the said central processor (6) consists of microprocessors RAM j(15) (Random Access Memory), ROM (16) (Read Only Memory), a central display (17), one or more serial/parallel port (18,19,20) and a keyboard, the said central processor having an output block connected to it through parallel port (19), the said output block consists of an array of decoders (14), an amplifying circuit (12), a relay matrix (13), the said output block are connected to main distribution frame (.11), -the said main distribution frame is connected to telephone(s) (5), the said input block, the central processor and the output block being connected to an uninterruptible power supply.

Title of Invention

AN INTRINSICALLY SAFE TELEPHONE EXCHANGE USEFUL FOR AREAS HAVING EXPLOSIVE ATMOSPHER

Abstract

An intrinsically safe telephone exchange useful for areas having explosive atmosphere which comprises an input block which consists of a decade counter (7), an intrinsically safe switch (8), a sample and hold circuit (9), a tristate buffer (10) and a main distribution frame (11), the said input block being connected to a central processor(6) through parallel port (18), the said central processor (6) consists of microprocessors RAM j(15) (Random Access Memory), ROM (16) (Read Only Memory), a central display (17), one or more serial/parallel port (18,19,20) and a keyboard, the said central processor having an output block connected to it through parallel port (19), the said output block consists of an array of decoders (14), an amplifying circuit (12), a relay matrix (13), the said output block are connected to main distribution frame (.11), -the said main distribution frame is connected to telephone(s) (5), the said input block, the central processor and the output block being connected to an uninterruptible power supply.

Full Text	This invention relates to an intrinsically safe telephone exe range useful for areas having explosive atmosphere. The invention particularly relates to a Microprocessor based intrinsic safe auto-cum-manual exchange for mines using central battery / local battery / sound powered. Such exchanges are useful for mines or places having explosive atmosphere such as petrochemical industries. It has hitherto been known to manufacture intrinsically safe central dispatcher system, auto interface and auto-cum manual excharige, in all of these, surface auto exchange (SAX) was used for the purpose of switching (interconnecting) various telephones. The existing microprocessor based exchanges for surface use, normally manufactured were not intrinsically safe. This system has the drawback when using central battery /local battery /sound — -powered. (i) there is need for normal surface automatic exchange in addition to total intrinsically safe interface. (ii) for the purpose r of> switching one, has. to^depend on the surf^pe automatic ■' "* exchange. (iii) incidentally if unsafe power reaches an area where flammable gases are likely to be present, the whole exchange becomes unsafe. The main object of the present invention is to develop an intrinsically safe auto cum manual microprocessor based telephone exchange, operated by local battery, central battery or sound powered, which will be free from the above drawbacks. Other objects of the present invention are : (i) a microprocessor could be employed to do switching, required for interconnecting various telephone pairs. This will avoid use of SAX completely. (ii) the exchange of unsafe power passing to an area where explosive atmosphere may exist, is totally eliminated. (iii) Large number of functions normally required to be done by an operator in the event of use of manual exchange could be transferred to microprocessor. (iv) Number of functions normally done by hardware may be performed using software. (v) Power is sent from surface to underground only when required for voice communication in case of central battery. Accordingly, the present invention provides an intrinsically safe telephone exchange useful for areas having explosive atmosphere which comprises an input block which consists of a decade counter (7), an intrinsically safe switch (8), a sample and hold circuit (9), a tristate buffer (10)and a main distribution frame(H), the said input block being connected to a central processor(6) through parallel port (18), the said central processor(6) consists of microprocessors RAM (15) (Random Access Memory), ROM (16) (Read only Memory), a central display (17), one or more serial/parallel port (18,19,20) and a keyboard ,the said central processor having an output block connected to it through parallel port (19), the said output block consists of an array of decoders(14), an amplifying circuit(12), a relay matrix (13) , the said output block are connected to main distribution frame(11) .the said main distribution frame is connected to telephone(s) (5), the said input block, the central processor and the output block being connected to an uninterruptible power supply. The invention will now be described with the help of drawings accompanying this specification where in fig.1 depicts the functional block diagram of the system and fig.2 shows the functional block diagram of the modules of the exchange. The intrinsically safe auto-cum-manual telephone exchange system of the present invention is particularly suited for communication in mines. It has a central console (1) uninterruptible power supply (2) intrinsically safe power supply (3) for charging batteries underground, interconnecting cable (4) and number of telephones (5). The exchange of the present invention consists of the following parts : (i) Uninterruptible Power Supply (2) (ii) Central Processor (6) (iii) Input Block, (7, 8, 9, 10, 11 Fig.2) (iv) Output Block (12,13,14,11 Fig.2) (v) Underground power supply (3) in case local battery is used. (i) Uninterruptible Power Supply (2) : It consists of 1 to 4 no. of 6-24 V and 180/400 AH battery which may be constantly float charged to serve the central exchange at the surface. (ii) Central Processor (6): This has got 8 bit (such as 8085) microprocessor (7) which consists of one or more 4 KB - 64 KB RAM (15), one or more 2 KB -32 KB of ROM (16) central display (17), one or more parallel port (18), (19), one or more serial port (20),m 44 to 1616 matrix keyboard (21). (iii) Input block : The input block consists of decade counter (7), I.S. switch(8), sample and hold circuit (9), tristate buffer (10), and Main distribution frame (11). The telephone are connected to microprocessor at the port (18V(19) through input block and main distribution frame. (iv) Output block: The output block consists of an array of decoders (14), which is connected to relay matrix (13), on the other side is connected to the telephones (5). All the telephones are connected to each channel through amplifying circuit (12) and relay matrix (13). (v) Underground Power Supply (local batten/); The batteiyof 6/12 V is used as local battery near each telephone set The batteries are charged from the surface. Operation of the equipment: The I.S. telephones and central telephone exchange are interconnected through pairs of telephone cables as shown in fig.1. When any telephone handset is lifted, the power from surface to underground cuts-off with the help of intrinsically safe switch (In case of sound powered telephones no power flows from surface to underground, white m case of local battery, the battery is placed at each subscriber). When handset is lifted in addition to cutting OFF of power, the calling subscriber number automatically gets entered into some free location of microprocessor which forms the channel. The microprocessor now waits for the called number. As the caning suoscnoer aiais the number of subscriber the called number automatically gets entered in RAM at a location next to the number of the calling subscriber. This forms a pair of numbers to be interconnected by the exchange. Simultaneously the calling tone starts going to the called subscriber. As soon as the called subscriber lifts the handset calling tone is switched OFF and the two telephones automatically get interconnected. At the expiry of conversation, the microprocessor eliminates the calling & called subscriber numbers, thereby making the channel free. The basic difference between Central battery, local battery and sound powered system lies only in mode of sending power for operating underground telephones. Microprocessor based switching for the exchange is common to all the three. The main advantages of the exchange are as follows: (i) An intrinsically safe central battery and sound powered microprocessor based auto cum manual telephone exchange for mines. (ii) No surface automatic exchange (SAX) for performing the switching operation. (iii) Change over from auto to manual could be done using software (iv) Better loud hailing to one or more points controlled by microprocessor. (v) The D.C. power may be fed only when it is needed. (vi) In case of local battery conversation between point to point in addition to communication through exchange. (vii) In case of sound powered exchange, amplification of voice is done at surface so no charging of battery or power feeding from underground in case of central battery is required. We claim: 1. An intrinsically safe telephone exchange useful for areas having explosive atmosphere which comprises an input block which consists of a decade counter (7), an intrinsically safe switch (8), a sample and hold circuit (9), a tristate buffer (10)and a main distribution frame(11), the said input block oeing connected tc a centra! processor(6) through parallel port (18), the said central processor(6) consists of microprocessors RAM (15) (Random Access Memory), ROM (16) (Read only Memory), a central display (17), one or more serial/parallel port (18,19,20) and a keyboard ,the said central processor having an output block connected to it through parallel port (19), the said output block consists of an array of decoders(14), an amplifying circuit(12), a relay matrix (13), the said output block are connected to main distribution frame(11), the said main distribution frame is connected to telephone(s) (5), the said input block, the central processor and the output block being connected to an uninterruptible power supply. 2. An intrinsically safe telephone exchange as claimed in claim 1 wherein the microprocessor is selected from an 8 bit having one or more 4 to 64 KB Random Access Memory, one or more 2 to 32 KB Read only Memory. 3. An intrinsically safe telephone exchange useful for areas having explosive atmosphere substantially as herein described with reference to the drawings accompanying this specification.

Full Text

This invention relates to an intrinsically safe telephone exe range useful for areas having explosive atmosphere.
The invention particularly relates to a Microprocessor based intrinsic safe auto-cum-manual exchange for mines using central battery / local battery / sound powered. Such exchanges are useful for mines or places having explosive atmosphere such as petrochemical industries.
It has hitherto been known to manufacture intrinsically safe central dispatcher system, auto interface and auto-cum manual excharige, in all of these, surface auto exchange (SAX) was used for the purpose of switching (interconnecting) various telephones. The existing microprocessor based exchanges for surface use, normally manufactured were not intrinsically safe.
This system has the drawback when using central battery /local battery /sound — -powered.
(i) there is need for normal surface automatic exchange in addition to total intrinsically safe interface.
(ii) for the purpose r of> switching one, has. to^depend on the surf^pe automatic ■' "* exchange.
(iii) incidentally if unsafe power reaches an area where flammable gases are likely to be present, the whole exchange becomes unsafe.
The main object of the present invention is to develop an intrinsically safe auto cum manual microprocessor based telephone exchange, operated by local battery, central battery or sound powered, which will be free from the above drawbacks.
Other objects of the present invention are :
(i) a microprocessor could be employed to do switching, required for interconnecting various telephone pairs. This will avoid use of SAX completely.
(ii) the exchange of unsafe power passing to an area where explosive atmosphere may exist, is totally eliminated.
(iii) Large number of functions normally required to be done by an operator in the event of use of manual exchange could be transferred to microprocessor.
(iv) Number of functions normally done by hardware may be performed using software.
(v) Power is sent from surface to underground only when required for voice communication in case of central battery.
Accordingly, the present invention provides an intrinsically safe telephone exchange useful for areas having explosive atmosphere which comprises an input block which consists of a decade counter (7), an intrinsically safe switch (8), a sample and hold circuit (9), a tristate buffer (10)and a main distribution frame(H), the said input block being connected to a central processor(6) through parallel port (18), the said central processor(6) consists of microprocessors RAM (15) (Random Access Memory), ROM (16) (Read only Memory), a central display (17), one or more serial/parallel port (18,19,20) and a keyboard ,the said central processor having an output block connected to it through parallel port (19), the said output block consists of an array of decoders(14), an amplifying circuit(12), a relay matrix (13) , the said output block are connected to main distribution frame(11) .the said main distribution frame is connected to telephone(s) (5), the said input block, the central processor and the output block being connected to an uninterruptible power supply.
The invention will now be described with the help of drawings accompanying this specification where in fig.1 depicts the functional block diagram of the system and fig.2 shows the functional block diagram of the modules of the exchange.
The intrinsically safe auto-cum-manual telephone exchange system of the present invention is particularly suited for communication in mines. It has a central console (1) uninterruptible power supply (2) intrinsically safe power supply (3) for charging batteries underground, interconnecting cable (4) and number of telephones (5).
The exchange of the present invention consists of the following parts :
(i) Uninterruptible Power Supply (2)
(ii) Central Processor (6)
(iii) Input Block, (7, 8, 9, 10, 11 Fig.2)
(iv) Output Block (12,13,14,11 Fig.2)
(v) Underground power supply (3) in case local battery is used.
(i) Uninterruptible Power Supply (2) : It consists of 1 to 4 no. of 6-24 V and 180/400 AH battery which may be constantly float charged to serve the central exchange at the surface.
(ii) Central Processor (6): This has got 8 bit (such as 8085) microprocessor (7) which consists of one or more 4 KB - 64 KB RAM (15), one or more 2 KB -32 KB of ROM (16) central display (17), one or more parallel port (18), (19), one or more serial port (20),m 4*4 to 16*16 matrix keyboard (21).
(iii) Input block : The input block consists of decade counter (7), I.S. switch(8), sample and hold circuit (9), tristate buffer (10), and Main distribution frame (11). The telephone are connected to microprocessor at the port (18V(19) through input block and main distribution frame.
(iv) Output block: The output block consists of an array of decoders (14), which is connected to relay matrix (13), on the other side is connected to the telephones (5). All the telephones are connected to each channel through amplifying circuit (12) and relay matrix (13).
(v) Underground Power Supply (local batten/); The batteiyof 6/12 V is used as local battery near each telephone set The batteries are charged from the
surface.
Operation of the equipment: The I.S. telephones and central telephone exchange are interconnected through pairs of telephone cables as shown in fig.1. When any telephone handset is lifted, the power from surface to underground cuts-off with the help of intrinsically safe switch (In case of sound powered telephones no power flows from surface to underground, white m case of local battery, the battery is placed at each subscriber). When handset is lifted in addition to cutting OFF of power, the calling subscriber number automatically gets entered into some free location of microprocessor which forms the channel. The microprocessor now waits for the called number. As the
caning suoscnoer aiais the number of subscriber the called number automatically gets entered in RAM at a location next to the number of the calling subscriber. This forms a pair of numbers to be interconnected by the exchange. Simultaneously the calling tone starts going to the called subscriber. As soon as the called subscriber lifts the handset calling tone is switched OFF and the two telephones automatically get interconnected. At the expiry of conversation, the microprocessor eliminates the calling & called subscriber numbers, thereby making the channel free.
The basic difference between Central battery, local battery and sound powered system lies only in mode of sending power for operating underground telephones. Microprocessor based switching for the exchange is common to all the three.
The main advantages of the exchange are as follows:
(i) An intrinsically safe central battery and sound powered microprocessor based auto cum manual telephone exchange for mines.
(ii) No surface automatic exchange (SAX) for performing the switching operation.
(iii) Change over from auto to manual could be done using software
(iv) Better loud hailing to one or more points controlled by microprocessor.
(v) The D.C. power may be fed only when it is needed.
(vi) In case of local battery conversation between point to point in addition to communication through exchange.
(vii) In case of sound powered exchange, amplification of voice is done at surface so no charging of battery or power feeding from underground in case of central battery is required.

We claim:
1. An intrinsically safe telephone exchange useful for areas having explosive
atmosphere which comprises an input block which consists of a decade counter (7), an
intrinsically safe switch (8), a sample and hold circuit (9), a tristate buffer (10)and a
main distribution frame(11), the said input block oeing connected tc a centra!
processor(6) through parallel port (18), the said central processor(6) consists of
microprocessors RAM (15) (Random Access Memory), ROM (16) (Read only Memory),
a central display (17), one or more serial/parallel port (18,19,20) and a keyboard ,the
said central processor having an output block connected to it through parallel port (19),
the said output block consists of an array of decoders(14), an amplifying circuit(12), a
relay matrix (13), the said output block are connected to main distribution frame(11),
the said main distribution frame is connected to telephone(s) (5), the said input block,
the central processor and the output block being connected to an uninterruptible power
supply.
2. An intrinsically safe telephone exchange as claimed in claim 1 wherein the
microprocessor is selected from an 8 bit having one or more 4 to 64 KB Random
Access Memory, one or more 2 to 32 KB Read only Memory.
3. An intrinsically safe telephone exchange useful for areas having explosive
atmosphere substantially as herein described with reference to the drawings
accompanying this specification.

Documents:

175-del-1995-abstract.pdf

175-del-1995-claims.pdf

175-del-1995-correspondence-others.pdf

175-del-1995-correspondence-po.pdf

175-del-1995-description (complete).pdf

175-del-1995-drawings.pdf

175-del-1995-form-1.pdf

175-del-1995-form-2.pdf

175-del-1995-form-4.pdf

175-del-1995-form-9.pdf

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Patent Number

189709

Indian Patent Application Number

175/DEL/1995

PG Journal Number

16/2003

Publication Date

19-Apr-2003

Grant Date

27-Jan-2004

Date of Filing

17-Feb-1995

Name of Patentee

COUNCIL OF SCIENTIFIC & INDUSTRIAL RESEARCH

Applicant Address

RAFI MARG, NEW DELHI-110001 INDIA.

Inventors:

#	Inventor's Name	Inventor's Address
1	SHANTI RAM MITRA	INSTRUMENTATION DIVISION, C.M.R.S, DHANBAD INDIA.
2	SUNIL SRIVASTAVA	INSTRUMENTATION DIVISION, C.M.R.S, DHANBAD INDIA.
3	EMANUAL TUDU	INSTRUMENTATION DIVISION, C.M.R.S, DHANBAD INDIA.
4	SUDHIR KUMAR	INSTRUMENTATION DIVISION, C.M.R.S, DHANBAD INDIA.
5	SATISH CHANDRA SRIVASTAVA	INSTRUMENTATION DIVISION, C.M.R.S. DHANBAD INDIA.

PCT International Classification Number

H01M 1/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA