Indian Patents. 251041:TOUCH CONTROLLED SWITCH APPARATUS HAVING A TWO WIRE INTERFACE

Title of Invention	TOUCH CONTROLLED SWITCH APPARATUS HAVING A TWO WIRE INTERFACE
Abstract	A touch sensor interfaces with a control system or controlled device using two wires. The output of the touch sensor controls an output switch.

Full Text	WO 2004/105244 PCT/US2004/014970 Two Wire Touch Sensor Interface CROSS REFERENCE TO RELATED APPLICATIONS This application claims priority form United States Provisional Patent Application Serial No. 60/470,961, filed on.May 15,2003, the disclosure of which is incorporated herein by reference. BACKGROUND OF THE INVENTION 1. The Technical Field The present invention is directed to methods and apparatus for interconnecting a field effect sensor with a control system or controlled device using only two wires. 2. The Related Art Touch sensors are often desirable as replacements for mechanical switches. However, certain limitations apply when replacing a mechanical switch with a touch sensor, For example, whereas a typical mechanical switch is a simple two terminal device, a conventional touch sensor typically requires three wires for operation, namely, a power input wire, a ground wire, and an output wire. Thus, replacement of a mechanical switch with a touch sensor often requires addition of a third wire that is not required for use with the mechanical switch. This adds cost and complexity and can render the use of a touch sensor as a replacement for a mechanical switch prohibitive in certain applications. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram illustrating the concepts of the present invention; HG. 2 is a schematic diagram illustrating an apparatus according to a preferred 1 WO 2004/105244 PCT/US2004/014970 embodiment of the present invention; FIG. 3 is a graph showing voltage output as a function of time of an output switch according to a preferred embodiment the present invention; and FIG. 4 is a schematic diagram illustrating an apparatus according to another preferred embodiment of the present invention. DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT FIG. 1 is a block diagram representing conceptually a device 10 according to a preferred embodiment of the present invention. Terminals J1,J2 are coupled to a source of operating voltage (not shown), for example, the wires leading to and from a mechanical switch that is to be replaced with a sensor apparatus according to the present invention. The first and second terminals of switching diode Dl are coupled to terminal Jl and the first terminal of capacitor Cl. The second terminal of storage capacitor Cl is coupled to termmal J2. The junction of switching diode Dl and storage capacitor Cl is coupled to the input of voltage regulator VR. The output of voltage regulator VR is coupled to the inputs of touch sensor TS and undervoltage detector UD. The outputs of touch sensor TS and undervoltage detector UD are coupled to inputs of output switch OS, the power terminals of which are coupled to terminals J1,J2, respectively. The grounds of each of voltage regulator VR, undervoltage detector UD, and touch sensor TS are coupled to terminal J2. In operation, the voltage across terminals J1J2 charges storage capacitor Cl through switching diode Dl. The voltage across terminals J1.J2 also biases voltage regulator VR through switching diode Dl. So long as the output from voltage regulator VR to the input of touch sensor TS is greater than a predetermined voltage, undervoltage detector UD allows touch sensor TS to control output switch OS. In this condition and with touch sensor 2 WO 2004/105244 PCT/US2004/014970 TS not actuated, output switch OS is "off," or non-conductive, emulating an open mechanical switch. In this condition and with touch sensor TS actuated, output switch OS is "on," or conductive, emulating a closed mechanical switch. However, if the output from voltage regulator VR to the input of touch sensor TS is lower than a predetermined voltage, undervoltage detector UD disables output switch OS. In this condition, output switch OS remains off regardless of the state of touch sensor TS. When output switch OS is off, the voltage across terminals J1,J2 is applied to storage capacitor Cl, as described above. When output switch OS is on, it essentially short circuits terminals J1,J2, reverse biasing switching diode Dl and removing any charging voltage from storage capacitor Cl. In this condition, storage capacitor Cl discharges through voltage regulator VR and touch sensor TS. Eventually, storage capacitor Cl discharges to a level where the input voltage to voltage regulator VR is insufficient to maintain a voltage regulator VR output voltage (and touch sensor TS input voltage) greater than the predetermined voltage discussed above. When the output voltage from voltage regulator VR falls below the predetermined voltage, undervoltage detector UD disables output switch OS, causing output switch OS to open, or return to the "off" state. With output switch OS open, or "off," voltage is again applied to storage capacitor Cl through switching diode Dl, charging storage capacitor Cl and biasing voltage regulator VR. In a typical physical embodiment, the foregoing cycle repeats such that output switch OS is closed or "on" about 95% or more of the time that touch sensor TS is continuously activated and open or "off" 100% of the time that touch sensor TS not activated. FIG. 2 illustrates schematically a device 20 constructed using commercially available components according to a preferred embodiment of the present invention. Device 20 is similar to device 10 described above in connection with FIG. 1, but incorporates the 3 WO 2004/105244 PCT/US2004/014970 functions of voltage regulator VR and undervoltage detector UD of the FIG. 1 embodiment in a single device, namely, voltage regulator Ul. Voltage regulator Ul preferably is embodied as an LP2951 voltage regulator available from National Semiconductor, among others. The "error" pin of this device is coupled to the control input of output switch OS. When the output voltage of voltage regulator Ul (and, thus, the input voltage to touch sensor TS) is lower than a predetermined voltage, the "error" pin.of voltage regulator Ul, and, therefore, the control input to output switch OS, is tied internally to ground. When the output voltage of voltage regulator Ul (and, thus, the input voltage to touch sensor TS) is greater than the predetermined voltage, the "error" pin of voltage regulator Ul is essentially tied internally to an open circuit. Device 20 also includes the following additional circuit elements not shown in the FIG. 1 embodiment: first peak current limiting resistor R5 coupled between terminal Jl and switching diode Dl; second peak current limiting resistor Rl coupled between switching diode Dl and storage capacitor Cl; zener diode D2 coupled in parallel with storage capacitor Cl; current limiting resistor R2 coupled between the output of touch sensor TS and the control input to output switch OS; and second capacitor C2 coupled between -the input to touch sensor TS and terminal J2. First and second peak current limiting resistors Rl and R5 can be omitted, but are desirable in automotive applications to mitigate EMC concerns and may be desirable in other applications, as well. Zener diode D2 protects voltage regulator VR from high voltage transients that might occur in, for example, systems having inductive loads. That is, if the input to zener diode D2 (and, therefore, the input voltage to voltage regulator VR) exceeds a predetermined value, then zener diode D2 will clamp the input voltage at the predetermined voltage. Zener diode D2 can be omitted from a particular application if transient protection is not of concern. Second capacitor C2 is provided to stabilize voltage 4 WO 2004/105244 PCT/US2004/014970 regulator Ul. In preferred embodiments, touch sensor TS is embodied as a touch sensor using the TS100 control circuit, available from TouchSensor Technologies, LLC of Wheaton, Illinois. Such a device is described in United States Patent No. 6,320,282, the disclosure of which is incorporated herein by reference. Preferably, output switch OS is a field effect transistor (FET), although output switch OS can be embodied in other ways, as would be known to one skilled in the art. The FIG. 2 embodiment is functionally similar to the FIG. 1 embodiment. That is, the voltage across terminals J1,J2 charges storage capacitor Cl through switching diode Dl and first and second peak current limiting resistors R5,R1. The voltage across terminals J1,J2 also biases voltage regulator Ul through switching diode Dl and first and second peak current limiting resistors R5,R1. So long as the output from voltage regulator Ul to the input of touch sensor TS is greater than a predetermined voltage, the "error" pin of voltage regulator Ul is tied internally to what is essentially an open circuit, as described above. In this condition, voltage regulator Ul allows touch sensor TS to control output switch OS. That is, with touch sensor TS not actuated, output switch OS is "off," emulating an open mechanical switch, and with touch sensor TS actuated, output switch OS is "on," emulating a closed mechanical switch. However, if the output from voltage regulator Ul to the input of touch sensor TS falls below the predetermined voltage, voltage regulator Ul disables output switch OS by tying the control input of output switch OS to ground, as described above. In this condition, output switch OS remains off, regardless of the state of touch sensor TS. When output switch OS is off, the voltage across terminals J1,J2 is applied to storage capacitor C1, as described above in connection with FIG. 1. When output switch OS 5 WO 2004/105244 PCT/US2004/014970 is on, it essentially short circuits terminals J1,J2, reverse biasing switching diode Dl and removing any charging voltage from storage capacitor Cl. 3n this condition, storage capacitor Cl discharges through voltage regulator Ul and touch sensor TS. Eventually, storage capacitor Cl discharges to a level where the input voltage to voltage regulator Ul is insufficient to maintain a voltage regulator Ul output voltage (and touch sensor TS input voltage) greater than the predetermined voltage discussed above. When the output voltage from voltage regulator Ul falls below the predetermined voltage, voltage regulator Ul disables output switch OS (by grounding its control input through voltage regulator Ul, as described above), causing output switch OS to open, or return to the "off'state. With output switch OS disabled, voltage is again applied to storage capacitor Cl through switching diode Dl, charging storage capacitor Cl and biasing voltage regulator Ul. In a prototype embodiment, the foregoing cycle repeats such that output switch OS is closed or "on" about 99.1 % or more of the time that touch sensor TS is continuously activated and open or "off' 100% of the time that touch sensor TS not activated. This is illustrated in FIG. 3, which is a plot of voltage across output switch OS as a function of time with touch sensor TS continuously stimulated. FIG. 4 illustrates an alternate embodiment of the present invention. The FIG. 4 embodiment is similar to the FIG, 2 embodiment, except that it omits voltage regulator Ul and capacitor C2. Here, zener diode D2 is selected to provide both transient protection and voltage regulation. This embodiment also adds pull-down resistor R3 coupled between the control input of output switch OS and current limiting resistor R2. Pull-down resistor R3 is optional, depending on the characteristics of touch sensor TS. More particularly, if touch sensor TS has only an active high output, as would be known to -one skilled in the art, then pull-down resistor R3 serves to generate a control voltage at the control input to output switch 6 WO 2004/105244 PCT/US2004/014970 OS. If touch sensor TS has both active high and active low outputs, then pull-down resistor R3 may be omitted and replaced with an open circuit. Further, current limiting resistor R2 could be omitted. In operation, the voltage between terminals Jl and 12 is applied to storage capacitor Cl and the input to touch sensor TS through first and second peak current limiting resistors R5,R1 and switching diode Dl. When touch switch TS is stimulated, its output goes high, creating a potential at the junction of pull-down resistor R3 and the control input to output switch OS, which, in rum, biases output switch OS to the "on" state. With output switch OS on, terminal Jl essentially short circuits to terminal J2 through output switch OS, reverse biasing switching diode Dl and removing any charging voltage from storage capacitor Cl. In this condition, storage capacitor Cl discharges through touch sensor TS. As it discharges, storage capacitor Cl continues to power touch sensor TS until the voltage across storage capacitor Cl is insufficient to drive touch, sensor TS. At this point, whether stimulated or not, touch switch TS no longer generates an output to the control terminal of output switch OS, and output switch OS opens. With output switch OS open, the voltage across terminals Jl and J2 again is applied to storage capacitor Cl and the foregoing cycle repeats. Although the FIG. 4 embodiment does not offer as great a level of precision and control as the FIG. 2 embodiment, it may be sufficiently precise to perform adequately in many applications, at lower cost than the FIG. 2 embodiment. The voltage, resistance, and capacitance values stated in the drawings are representative, preferred values. Other values of voltage, resistance, and capacitance may be used, as well, as would be readily determined by one skilled in the art. While several embodiments of the present invention have been shown and described above, it will be obvious to those skilled in the art that numerous modifications can 7 WO 2004/105244 PCT/US2004/014970 be made without departing from the spirit of the invention, the scope of which is defined by the claims below. 8 WO 2004/105244 PCT/US2004/014970 CLAIMS I claim: 1. A touch controlled switch apparatus having a two wire interface, comprising: an output switch having an input terminal coupled to a source of high voltage and an output terminal coupled to a source of low voltage; a first diode having a first terminal coupled to said source of high voltage; a first capacitor having a first terminal coupled to said source of low voltage and a second terminal coupled to a second terminal of said first diode; and a touch sensor having an input coupled to the junction of said first diode and said first capacitor, said touch sensor further having a control output coupled to a control input terminal of said output switch. 2. The apparatus of claim 1 further comprising a voltage regulator coupled between said input of said touch sensor and said junction of said first diode and said first capacitor. 9 A touch sensor interfaces with a control system or controlled device using two wires. The output of the touch sensor controls an output switch.

Full Text

WO 2004/105244 PCT/US2004/014970
Two Wire Touch Sensor Interface
CROSS REFERENCE TO RELATED APPLICATIONS
This application claims priority form United States Provisional Patent
Application Serial No. 60/470,961, filed on.May 15,2003, the disclosure of which is
incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. The Technical Field
The present invention is directed to methods and apparatus for interconnecting
a field effect sensor with a control system or controlled device using only two wires.
2. The Related Art
Touch sensors are often desirable as replacements for mechanical switches.
However, certain limitations apply when replacing a mechanical switch with a touch sensor,
For example, whereas a typical mechanical switch is a simple two terminal device, a
conventional touch sensor typically requires three wires for operation, namely, a power input
wire, a ground wire, and an output wire. Thus, replacement of a mechanical switch with a
touch sensor often requires addition of a third wire that is not required for use with the
mechanical switch. This adds cost and complexity and can render the use of a touch sensor as
a replacement for a mechanical switch prohibitive in certain applications.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram illustrating the concepts of the present invention;
HG. 2 is a schematic diagram illustrating an apparatus according to a preferred
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WO 2004/105244 PCT/US2004/014970
embodiment of the present invention;
FIG. 3 is a graph showing voltage output as a function of time of an output
switch according to a preferred embodiment the present invention; and
FIG. 4 is a schematic diagram illustrating an apparatus according to another
preferred embodiment of the present invention.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT
FIG. 1 is a block diagram representing conceptually a device 10 according to a
preferred embodiment of the present invention. Terminals J1,J2 are coupled to a source of
operating voltage (not shown), for example, the wires leading to and from a mechanical
switch that is to be replaced with a sensor apparatus according to the present invention. The
first and second terminals of switching diode Dl are coupled to terminal Jl and the first
terminal of capacitor Cl. The second terminal of storage capacitor Cl is coupled to termmal
J2. The junction of switching diode Dl and storage capacitor Cl is coupled to the input of
voltage regulator VR. The output of voltage regulator VR is coupled to the inputs of touch
sensor TS and undervoltage detector UD. The outputs of touch sensor TS and undervoltage
detector UD are coupled to inputs of output switch OS, the power terminals of which are
coupled to terminals J1,J2, respectively. The grounds of each of voltage regulator VR,
undervoltage detector UD, and touch sensor TS are coupled to terminal J2.
In operation, the voltage across terminals J1J2 charges storage capacitor Cl
through switching diode Dl. The voltage across terminals J1.J2 also biases voltage regulator
VR through switching diode Dl. So long as the output from voltage regulator VR to the
input of touch sensor TS is greater than a predetermined voltage, undervoltage detector UD
allows touch sensor TS to control output switch OS. In this condition and with touch sensor
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WO 2004/105244 PCT/US2004/014970
TS not actuated, output switch OS is "off," or non-conductive, emulating an open mechanical
switch. In this condition and with touch sensor TS actuated, output switch OS is "on," or
conductive, emulating a closed mechanical switch. However, if the output from voltage
regulator VR to the input of touch sensor TS is lower than a predetermined voltage,
undervoltage detector UD disables output switch OS. In this condition, output switch OS
remains off regardless of the state of touch sensor TS.
When output switch OS is off, the voltage across terminals J1,J2 is applied to
storage capacitor Cl, as described above. When output switch OS is on, it essentially short
circuits terminals J1,J2, reverse biasing switching diode Dl and removing any charging
voltage from storage capacitor Cl. In this condition, storage capacitor Cl discharges through
voltage regulator VR and touch sensor TS. Eventually, storage capacitor Cl discharges to a
level where the input voltage to voltage regulator VR is insufficient to maintain a voltage
regulator VR output voltage (and touch sensor TS input voltage) greater than the
predetermined voltage discussed above. When the output voltage from voltage regulator VR
falls below the predetermined voltage, undervoltage detector UD disables output switch OS,
causing output switch OS to open, or return to the "off" state. With output switch OS open, or
"off," voltage is again applied to storage capacitor Cl through switching diode Dl, charging
storage capacitor Cl and biasing voltage regulator VR. In a typical physical embodiment, the
foregoing cycle repeats such that output switch OS is closed or "on" about 95% or more of
the time that touch sensor TS is continuously activated and open or "off" 100% of the time
that touch sensor TS not activated.
FIG. 2 illustrates schematically a device 20 constructed using commercially
available components according to a preferred embodiment of the present invention. Device
20 is similar to device 10 described above in connection with FIG. 1, but incorporates the
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WO 2004/105244 PCT/US2004/014970
functions of voltage regulator VR and undervoltage detector UD of the FIG. 1 embodiment in
a single device, namely, voltage regulator Ul. Voltage regulator Ul preferably is embodied
as an LP2951 voltage regulator available from National Semiconductor, among others. The
"error" pin of this device is coupled to the control input of output switch OS. When the
output voltage of voltage regulator Ul (and, thus, the input voltage to touch sensor TS) is
lower than a predetermined voltage, the "error" pin.of voltage regulator Ul, and, therefore,
the control input to output switch OS, is tied internally to ground. When the output voltage of
voltage regulator Ul (and, thus, the input voltage to touch sensor TS) is greater than the
predetermined voltage, the "error" pin of voltage regulator Ul is essentially tied internally to
an open circuit.
Device 20 also includes the following additional circuit elements not shown in
the FIG. 1 embodiment: first peak current limiting resistor R5 coupled between terminal Jl
and switching diode Dl; second peak current limiting resistor Rl coupled between switching
diode Dl and storage capacitor Cl; zener diode D2 coupled in parallel with storage capacitor
Cl; current limiting resistor R2 coupled between the output of touch sensor TS and the
control input to output switch OS; and second capacitor C2 coupled between -the input to
touch sensor TS and terminal J2. First and second peak current limiting resistors Rl and R5
can be omitted, but are desirable in automotive applications to mitigate EMC concerns and
may be desirable in other applications, as well. Zener diode D2 protects voltage regulator VR
from high voltage transients that might occur in, for example, systems having inductive loads.
That is, if the input to zener diode D2 (and, therefore, the input voltage to voltage regulator
VR) exceeds a predetermined value, then zener diode D2 will clamp the input voltage at the
predetermined voltage. Zener diode D2 can be omitted from a particular application if
transient protection is not of concern. Second capacitor C2 is provided to stabilize voltage
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WO 2004/105244 PCT/US2004/014970
regulator Ul.
In preferred embodiments, touch sensor TS is embodied as a touch sensor
using the TS100 control circuit, available from TouchSensor Technologies, LLC of Wheaton,
Illinois. Such a device is described in United States Patent No. 6,320,282, the disclosure of
which is incorporated herein by reference. Preferably, output switch OS is a field effect
transistor (FET), although output switch OS can be embodied in other ways, as would be
known to one skilled in the art.
The FIG. 2 embodiment is functionally similar to the FIG. 1 embodiment.
That is, the voltage across terminals J1,J2 charges storage capacitor Cl through switching
diode Dl and first and second peak current limiting resistors R5,R1. The voltage across
terminals J1,J2 also biases voltage regulator Ul through switching diode Dl and first and
second peak current limiting resistors R5,R1. So long as the output from voltage regulator
Ul to the input of touch sensor TS is greater than a predetermined voltage, the "error" pin of
voltage regulator Ul is tied internally to what is essentially an open circuit, as described
above. In this condition, voltage regulator Ul allows touch sensor TS to control output
switch OS. That is, with touch sensor TS not actuated, output switch OS is "off," emulating
an open mechanical switch, and with touch sensor TS actuated, output switch OS is "on,"
emulating a closed mechanical switch. However, if the output from voltage regulator Ul to
the input of touch sensor TS falls below the predetermined voltage, voltage regulator Ul
disables output switch OS by tying the control input of output switch OS to ground, as
described above. In this condition, output switch OS remains off, regardless of the state of
touch sensor TS.
When output switch OS is off, the voltage across terminals J1,J2 is applied to
storage capacitor C1, as described above in connection with FIG. 1. When output switch OS
5

WO 2004/105244 PCT/US2004/014970
is on, it essentially short circuits terminals J1,J2, reverse biasing switching diode Dl and
removing any charging voltage from storage capacitor Cl. 3n this condition, storage capacitor
Cl discharges through voltage regulator Ul and touch sensor TS. Eventually, storage
capacitor Cl discharges to a level where the input voltage to voltage regulator Ul is
insufficient to maintain a voltage regulator Ul output voltage (and touch sensor TS input
voltage) greater than the predetermined voltage discussed above. When the output voltage
from voltage regulator Ul falls below the predetermined voltage, voltage regulator Ul
disables output switch OS (by grounding its control input through voltage regulator Ul, as
described above), causing output switch OS to open, or return to the "off'state. With output
switch OS disabled, voltage is again applied to storage capacitor Cl through switching diode
Dl, charging storage capacitor Cl and biasing voltage regulator Ul. In a prototype
embodiment, the foregoing cycle repeats such that output switch OS is closed or "on" about
99.1 % or more of the time that touch sensor TS is continuously activated and open or "off'
100% of the time that touch sensor TS not activated. This is illustrated in FIG. 3, which is a
plot of voltage across output switch OS as a function of time with touch sensor TS
continuously stimulated.
FIG. 4 illustrates an alternate embodiment of the present invention. The FIG.
4 embodiment is similar to the FIG, 2 embodiment, except that it omits voltage regulator Ul
and capacitor C2. Here, zener diode D2 is selected to provide both transient protection and
voltage regulation. This embodiment also adds pull-down resistor R3 coupled between the
control input of output switch OS and current limiting resistor R2. Pull-down resistor R3 is
optional, depending on the characteristics of touch sensor TS. More particularly, if touch
sensor TS has only an active high output, as would be known to -one skilled in the art, then
pull-down resistor R3 serves to generate a control voltage at the control input to output switch
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WO 2004/105244 PCT/US2004/014970
OS. If touch sensor TS has both active high and active low outputs, then pull-down resistor
R3 may be omitted and replaced with an open circuit. Further, current limiting resistor R2
could be omitted.
In operation, the voltage between terminals Jl and 12 is applied to storage
capacitor Cl and the input to touch sensor TS through first and second peak current limiting
resistors R5,R1 and switching diode Dl. When touch switch TS is stimulated, its output goes
high, creating a potential at the junction of pull-down resistor R3 and the control input to
output switch OS, which, in rum, biases output switch OS to the "on" state. With output
switch OS on, terminal Jl essentially short circuits to terminal J2 through output switch OS,
reverse biasing switching diode Dl and removing any charging voltage from storage capacitor
Cl. In this condition, storage capacitor Cl discharges through touch sensor TS. As it
discharges, storage capacitor Cl continues to power touch sensor TS until the voltage across
storage capacitor Cl is insufficient to drive touch, sensor TS. At this point, whether
stimulated or not, touch switch TS no longer generates an output to the control terminal of
output switch OS, and output switch OS opens. With output switch OS open, the voltage
across terminals Jl and J2 again is applied to storage capacitor Cl and the foregoing cycle
repeats. Although the FIG. 4 embodiment does not offer as great a level of precision and
control as the FIG. 2 embodiment, it may be sufficiently precise to perform adequately in
many applications, at lower cost than the FIG. 2 embodiment.
The voltage, resistance, and capacitance values stated in the drawings are
representative, preferred values. Other values of voltage, resistance, and capacitance may be
used, as well, as would be readily determined by one skilled in the art.
While several embodiments of the present invention have been shown and
described above, it will be obvious to those skilled in the art that numerous modifications can
7

WO 2004/105244 PCT/US2004/014970
be made without departing from the spirit of the invention, the scope of which is defined by
the claims below.
8

WO 2004/105244 PCT/US2004/014970
CLAIMS
I claim:
1. A touch controlled switch apparatus having a two wire interface, comprising:
an output switch having an input terminal coupled to a source of high voltage and an
output terminal coupled to a source of low voltage;
a first diode having a first terminal coupled to said source of high voltage;
a first capacitor having a first terminal coupled to said source of low voltage and a
second terminal coupled to a second terminal of said first diode; and
a touch sensor having an input coupled to the junction of said first diode and said first
capacitor, said touch sensor further having a control output coupled to a control input
terminal of said output switch.
2. The apparatus of claim 1 further comprising a voltage regulator coupled between said
input of said touch sensor and said junction of said first diode and said first capacitor.
9

A touch sensor interfaces with a control system or controlled device using two wires. The output of the touch sensor controls an output switch.

Documents:

02288-kolnp-2005-abstract.pdf

02288-kolnp-2005-claims.pdf

02288-kolnp-2005-description complete.pdf

02288-kolnp-2005-drawings.pdf

02288-kolnp-2005-form 1.pdf

02288-kolnp-2005-form 3.pdf

02288-kolnp-2005-form 5.pdf

02288-kolnp-2005-international publication.pdf

2288-KOLNP-2005-(15-12-2011)-CORRESPONDENCE.pdf

2288-KOLNP-2005-(15-12-2011)-FORM-2.pdf

2288-KOLNP-2005-(15-12-2011)-FORM-3.pdf

2288-KOLNP-2005-(15-12-2011)-OTHERS.pdf

2288-KOLNP-2005-CORRESPONDENCE 1.1.pdf

2288-KOLNP-2005-CORRESPONDENCE 1.2.pdf

2288-KOLNP-2005-CORRESPONDENCE 1.3.pdf

2288-KOLNP-2005-CORRESPONDENCE-1.1.pdf

2288-KOLNP-2005-CORRESPONDENCE-1.4.pdf

2288-KOLNP-2005-CORRESPONDENCE.pdf

2288-KOLNP-2005-CORRESPONDENCE1.5.pdf

2288-KOLNP-2005-EXAMINATION REPORT.pdf

2288-KOLNP-2005-FORM 13.pdf

2288-KOLNP-2005-FORM 18.pdf

2288-KOLNP-2005-FORM 3.pdf

2288-KOLNP-2005-FORM 5.pdf

2288-KOLNP-2005-GPA.pdf

2288-KOLNP-2005-GRANTED-ABSTRACT.pdf

2288-KOLNP-2005-GRANTED-CLAIMS.pdf

2288-KOLNP-2005-GRANTED-DESCRIPTION (COMPLETE).pdf

2288-KOLNP-2005-GRANTED-DRAWINGS.pdf

2288-KOLNP-2005-GRANTED-FORM 1.pdf

2288-KOLNP-2005-GRANTED-FORM 2.pdf

2288-KOLNP-2005-GRANTED-LETTER PATENT.pdf

2288-KOLNP-2005-GRANTED-SPECIFICATION.pdf

2288-KOLNP-2005-OTHERS.pdf

2288-KOLNP-2005-OTHERS1.1.pdf

2288-KOLNP-2005-REPLY TO EXAMINATION REPORT.pdf

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Patent Number

251041

Indian Patent Application Number

2288/KOLNP/2005

PG Journal Number

08/2012

Publication Date

24-Feb-2012

Grant Date

17-Feb-2012

Date of Filing

16-Nov-2005

Name of Patentee

TOUCHSENSOR TECHNOLOGIES, LLC

Applicant Address

203 NORTH GABLES BOULEVARD, WHEATON, IL 60187, U.S.A.

Inventors:

#	Inventor's Name	Inventor's Address
1	HOEKSTRA, ERIC, J	16418 RANSOM STREET, HOLLAND, MI 49424 U.S.A.

PCT International Classification Number

H03K 17/96, 17/94

PCT International Application Number

PCT/US2004/014970

PCT International Filing date

2004-05-13

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	60/470, 961	2003-05-15	U.S.A.