4,731,548
`[11] Patent Number:
`[19]
`United States Patent
`
`llngraham
`[45] Date of Patent: Mar. 15, 1988
`
`[54] TOUCH CONTROL SWITCH CIRCUIT
`_
`_
`[75]
`Inventor: Ronald D. Ingraham. ancy1Mlch-
`.
`,
`.
`-
`[73] Ass‘gnee'
`it???“ CMW'amn’ Reed C‘ty’
`1° -
`[21] Appl- No_, 913,084
`.
`[22] Filed:
`
`sep. 29, 1986
`
`1111. C1.4 ............................................. H01H 35/00
`[51]
`[52] US. Cl. .................................... 307/116; 307/308;
`307/632; ZOO/DIG 1
`[58] Field Of Search ............... 307/116, 125, 252, 308,
`315/34, 74, 203, 246, 362; 318/345, 446;
`323/19, 24; 328/5;. 200/DIG. l
`
`[56]
`
`References Cited
`U‘S' PATENT DOCUMENTS
`3,549,909 12/1970 Adelson et a1.
`..................... 307/252
`3,541,410
`2/1972 VOECISbng --------- 313/345
`
`3’651’391
`3/1972 VOgFISberg """"" 318/446
`
`
`3,666,988
`5/1972 Belhs ...............
`. 307/116 X
`3,899,713
`8/1975 Barkan et a1.
`307/308 x
`
`3,919,596 11/1975 Bellis .................... 307/308 x
`
`3,965,465
`6/1976 Alexander
`..... 340/274 R
`
`3,984,757 10/ 1976 Gott et al.
`.. 315/246 X
`410161453 4/1977 Moenflig --
`- 307/303 X
`4,031,408
`6/1977 Holz .............. 307/116
`
`4,101,805
`7/1978 Stone
`307/308 x
`
`..... 307/116
`4,119,864 10/1978 Patrizio
`
`5/1979 Raupp ................................. 315/362
`4,152,629
`
`4,159,473
`6/1979 Senk ................................ 307/116 x
`4,210,822
`7/1980 Wem ........................... 307/116
`
`4,211,959
`7/1980 Deavenport et al.
`307/308 x
`4,213,061 '7/1980 Conner ......................... 307/116
`
`1/1981 Chiang ..
`307/116 x
`4,246,533
`
`4,264,831
`4/1981 Wem .....
`307/116x
`4,289,972
`9/1981 Wem ........
`307/116
`4,289,980 9/1981 McLaughlin
`307/308
`
`307/116 x
`4,308,443 12/1981 Tucker et a1.
`
`307/116 x
`4,323,829 4/1982 Witney et al.
`4,360,737 “/1932 Leopold _____________________________ 307/116
`
`Primary Examiner—William M. Shoop, Jr.
`Assistant Examiner—Sharon D. Logan
`Attorney, Agent, or Firm—Price, Heneveld, Cooper,
`DeWitt & Litton
`
`ABSTRACT
`[57]
`in
`A touch controlled electronic switching circuit
`which the body capacitance of the person actuating the
`device is coupled in series with current limiting resistors
`and a capacitor with the junction coupled to a logic
`.
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`rent control Signal- The 10810 Clrcmt has an output cou-
`pled to the gate terminal of a Triac coupled to a load for
`selectively applying current to said load during both
`half-cycles of each cycle of the line voltage supplied to
`-
`the Tnac and load"
`
`19 Claims, 1 Drawing Figure
`
`
`
`
`”5
`VAC
`
`4O
`
`NEUTRAL
`
`1
`
`APPLE 1016
`
`1
`
`APPLE 1016
`
`

`

`US» Patent
`
`Mar. KS, 11988
`
`4,73l,548
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`ll
`
`TOUCH CONTROL SWITCH CIRCUIT
`
`BACKGROUND OF THE INVENTION
`
`4,731,548
`
`2
`ing description thereof together with reference to the
`accompanying drawing in which:
`BRIEF DESCRIPTION OF THE DRAWING
`
`The present invention relates to an electrical circuit
`and particularly to a touch controlled electrical switch-
`ing circuit.
`There exists a variety of electrical switching circuits
`which respond to a person’s touch on a touch pad
`which can be in the form of a lamp base or a specific
`surface area of an electrical appliance to be actuated.
`Such circuits represent a convenient manner by which a
`consumer can easily operate appliances without the
`need for manually actuating a conventional
`toggle,
`push-button or other type switch. Touch controlled
`electrical switching circuits have become increasingly
`popular; for example, in use in controlling table lamps,
`floor lamps and the like although they have other appli-
`cations as well. U.S. Pat. Nos. 4,119,864 and 4,360,737
`are representative of existing touch controlled switch
`circuits. Typically, such circuits employ the human
`body as an antenna for picking up 60 Hz radiation exist-
`ing in an environment by virtue of the line frequency
`power in the building and utilizes the induced voltage as
`a trigger signal for controlling the touch controlled
`electrical circuit. Such systems, however, can suffer
`from erratic operation due to variations in the nature of
`the ambient 60 Hz field and the physiological makeup of
`the person utilizing the system. Also the prior art sys-
`tems typically utilize a pulse control for controlling a
`solid-state switch such as a Triac to be conductive only
`during a portion of each cycle of operation of the AC
`power supply thereby reducing the efficiency of such
`systems.
`.
`
`SUMMARY OF THE PRESENT INVENTION
`
`The system of the present invention provides an im-
`proved touch controlled electronic switching circuit in
`which the body capacitance of the person actuating the
`device is coupled in a voltage dividing circuit employed
`to provide a logic output signal for controlling a DC
`trigger level applied to a Triac or other bilateral solid-
`state switch coupled between the line voltage source
`and a load to be controlled. In the preferred embodi-
`ment of the invention, the body capacitance is coupled
`in series with current limiting resistors and a second
`capacitor with the junction coupled to a solid-state
`switch for providing a control ouput signal to a logic
`circuit which responds thereto to provide a direct cur-
`rent control signal. In the preferred embodiment of the
`invention also, the logic circuit includes a D-flip/flop
`circuit having its output coupled to the input gate termi-
`nal of a Triac for providing a direct current control
`signal during each half-cycle of each cycle of the line
`voltage supplied to the Triac and load.
`Such a circuit provides improved reliability of opera-
`tion since it does not rely upon induced voltage for its
`operation. Further, by utilizing a direct current control
`signal for the solid—state switch, the Triac switch is
`rendered conductive near the beginning of each half-
`cycle of operation and remains conductive during each
`half-cycle of each cycle of operation. Thus, through a
`DC gate signal,
`inductive loads such as fluorescent
`lights, motors, etc., may be controlled. These and other
`objects, features and advantages of the present inven-
`tion can best be understood by reference to the folow-
`
`lO
`
`[5
`
`20
`
`25
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`30
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`35
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`45
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`50
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`55
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`60
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`65
`
`FIG. 1 is an electrical circuit diagram in schematic
`form of the system of the present invention.
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENT
`
`In FIG. I, the electrical circuit 10 for providing a
`touch controlled electrical switch is shown and includes
`a touch plate 12 as its control input element which is
`touched by a person for actuation of the electrical
`switching circuit. The switching circuit includes a bidi-
`rectional solid-state switch 20 such as a Triac having
`one power terminal 21 coupled to the one side of the
`typically 115 volt 60 Hz AC supply line 30 and its re-
`maining power terminal 22 coupled to one terminal 24
`of a load 26 to be controlled. The remaining terminal 27
`of the load is coupled to the line neutral conductor 40.
`A series spike suppression resistor 25 and capacitor 28
`are coupled across the Triac 20 to prevent false turn-on.
`The circuit 10 may include a plug which connects
`directly into, for example, a wall socket to provide
`connections for lines 30 and 40 to the building’s wiring
`system and a socket for receiving terminals 24 and 27 of
`a load 26 such as a lamp to be controlled. The circuit 10
`may be built directly into, for example, a base or other
`mechanical structure associated with a lamp or other
`appliance and wired directly as shown in FIG. 1 with a
`plug for plugging directly into a power outlet of the
`building’s power supply system.
`The touch plate typically is a conductive element
`which is insulated from the remaining body or the like
`of a lamp base or other appliance and is in a location
`readily accessible by the user. The user’s body includes
`a capacitance portion represented by capacitor 42 in
`FIG. I which may range in a typical person from be-
`tween 100-to 300 picofarads. When a person touches
`touch plate 12, this body capacitance is coupled to a
`series voltage dividing circuit coupled to the AC supply
`and including at least one other capacitor 47. The touch
`plate or terminal 12 is coupled to one terminal of a first
`resistor 44 serially coupled to a second resistor 46 hav-
`ing its terminal remote from resistor 44 coupled to the
`base terminal 52 of a solid-state switch 50 comprising a
`PNP transistor. Base 52 is also coupled to line supply
`conductor 30 by a first diode 45 having a cathode cou-
`pled to the conductor 30 and an anode coupled to base
`terminal 52. Capacitor 47 is also coupled between base
`terminal 52 and line 30 and is coupled effectively in
`series with body capacitor 42 to form a capacitive volt- '
`age divider including series resistors 44 and 46 between
`coductor 30 and ground which also corresponds to the
`ground conductor 40 of the building’s supply line. The
`emitter terminal 41 of transistor 50 is coupled directly to
`conductor 30 while the collector terminal 53 is coupled
`to a capacitor 55 coupled in parallel with resistor 56 and
`having their terminals remote from collector terminal
`53 coupled to a negative DC supply conductor 60
`which is coupled to the neutral or ground conductor 40
`through a resistor 62 and series coupled rectifier diode
`64 as shwon in FIG. 1.
`Transistor 50 is biased in a normally nonconductive
`state by a resistor 54 coupled between base terminal 52
`and emitter terminal 51 such that in the absence of body
`capacitace 42, transistor 50 will be nonconductive and
`capacitor 55 will be discharged by bleeder resistor 56
`
`3
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`such that the output signal present at collector terminal
`53 of transistor 50 will be a logic zero or low level. This
`input circuit thus will provide a first control output
`signal which is at a logic low level when plate 12 is not
`touched and a second level or logic high level when the 5
`plate 12 is touched. The touching of plate completes an
`AC voltage divider between line 30 and 40 including
`series capacitors 47 and 42 with resistors 44 and 46
`serially. Thus with the presence of capacitor 42, the AC
`voltage at the base 52 of transistor 50 during the positive 10
`half-cycles of the line voltage will be decreased to for-
`wardly bias the emitter-to-base junction thereby render-
`ing transistor '50 conductive. The collector current thus
`charges capacitor 55 to provide a positive voltage level
`. or logic “1” output signal for application to circuit 80. 15
`Resistors 44 and 46 should each have a resistance of at
`least 1 megohms, and in the preferred embodiment of
`the invention, each have a value of 4.7 megohms which
`provides isolation between touch plate 12 and suppply
`line 30 so that no harmful electrical current can be
`supplied to a person touching plate 12. Two serially
`coupled resistors are employed in the unlikely event
`that one resistor could short out, the second resistor
`continues to provide protection for the user of the cir-
`cuit. Capacitor 47 was a 0.0] Mfd capacitor in the pre-
`ferred embodiment. Diode 45 prevents the base-to-emit-
`ter junction of transistor from being subjected. to rel
`verse breakover voltages.
`' A 15 volt DC power supply 70 is included within
`' circuit 10 for providing power to the logic circuits 80
`and 90. Supply 70 includes resistor 62 and diode 64 and
`v 9a voltage regulator circuit including a 15 volt Zener
`~diode 72 coupled in parallel with a resistor 74 and ca-
`pacitor 76. One termninal of this parallel combination is
`coupled to conductor 30, as shown, while the remaining
`terminal is coupled to DC supply conductor 60 which.
`applies a negative 15 volt DC for the logic circuit now
`:described.
`The logic circuit coupled to transistor 50 and to the
`.
`“gate terminal 23 of Triac 20 comprises a two-stage com-
`‘mercially available 4013B integrated circuit having one
`half coupled as a squaring circuit 80 and the second half
`coupled as a conventional D-flip/flop circuit 90. The
`terminal identification numbers on circuits 80 and 90 are
`the standard commercial identification numbers of the 45
`integrated circuit.
`The squaring circuit 80 responds to positive going 60
`Hz clock pulses from conductor 40 through current
`limiting resistor 82 which pulses are applied to the clock
`input terminal 11 of the circuit. The squaring circuit 50
`also receives the control signal from the collector of
`transistor 50 present across resistor 56 which is applied
`to input terminal 9 which is the D input of the circuit.
`Circuit 80 responds to a positive signal on input 11
`when body capacity 42 is present to provide a positive 55
`pulse at the Q output terminal 13. This signal is shown
`by waveform A in the FIG. and has a pulse width corre-
`sponding generally to the length of time plate 12 is
`touched. Pulse A is applied to input terminal 3 of circuit
`90 which has its SET terminal 6 coupled to conductor 60
`60 through resistor 92 and to conductor 30 through
`capacitor 94 such that when initial power is turned on,
`this voltage divider holds the SET terminal in a high
`state assuring that the Q output at terminal 1 remains
`high and therefore the Triac 20 which is coupled to the 65
`Q output terminal 1 of circuit 90 through resistor 96
`remains nonconductive when power is initially applied
`to the circuit. The D and Q terminals 5 and 2, respec-
`
`4,731,548
`
`4
`tively, of circuit 9 are intercoupled, while terminal 14
`(Van) of circuit 90 is coupled to line 30 as seen in the
`FIGURE.
`
`OPERATION
`
`Having described the components and their intercon-
`nection to form the circuit of the present invention, a
`description of a cycle of operation is now presented. As
`noted above, when power is initially applied to the
`circuit and there is no body capacitance 42 in the cir-
`cuit, the biasing of the SET terminal of D-flip/flop 90
`will maintain the Q output high and therefore the Triac
`20 in the nonconductive state. When touch plate 12 is
`touched thereby adding capacitance 42, as noted earlier,
`transistor 50 is rendered conductive during the positive
`half-cycles of each cycle of the AC supply line voltage,
`thereby charging capacitor 55 and providing a positive
`output signal indicated by waveform A in the FIGURE
`at the Q output 13 of squaring circuit 80. This signal is
`applied to the clock input terminal 3 of D-flip/flop 90
`causing the output terminal 1 to switch to the state of
`terminal 5 which on initial power up was at the low
`level. Thus, when plate 12 is first touched at a time t1, a
`negative pulse indicated by waveform B in the FIG-
`URE will be applied to the Triac 20 rendering it con-
`ductive and illuminating lamp 26 or applying power to
`whatever appliance is coupled to terminals 24 and 27.
`When the user removes contact with touch plate 12,
`transistor 50 is nonconductive and capacitor 55 dis-
`charges through resistor 56; however, the D-flip/flop
`9D is latched and output 1 remains at a direct current
`low level and the Triac 20 remains conductive during
`each half-cycle of each cycle of the applied line fre-
`quency voltage. The next time, however, touch plate 12
`is touched, generating a second positive pulse on input
`terminal 9 of squaring circuit 80, a second positive pulse
`also indicatedby waveform A is applied to terminal 3 of
`circuit 90. The flip/flop circuit 90 responds to change
`states and provide a positive going edge to waveform B
`indicated at time t2 in the Figure, thereby turning the
`Triac 20 off and extinguishing lamp 26. Thus, alternate
`touches of plate 12 will cause flip/flop 90 to change
`states for providing the control pulse to the Triac 20.
`Waveform B provides a continuous DC signal as op—
`posed to alternate half-cycle pulses thereby rendering
`the Triac conductive during the entire cycle of line
`frequency voltage applied between conductors 30 and
`40 which efficiently provides power to lamp 26. A
`suitable adjustable time delay and reset circuit can be
`coupled between the squaring circuit 80 and triac 20 to
`provide an adjustable duty cycle of power to load 26.
`The circuit of the present invention therefore pro-
`vides a relatively inexpensive and efficient circuit in
`which operation is improved by providing an AC volt-
`age dividing network including the body capacitance as
`a controlled element and a DC control signal for the
`gate of a bidirectional switch such as a Triac. The sys-
`tem utilizes a minimum of components with safety fea-
`tures for protecting the user. It will become apparent to
`those skilled in the art that various modifications to the
`preferred embodiment of the invention can be made
`without departing from the spirit or scope thereof as
`defined by the appended claims.
`The embodiments of the invention in which an exclu-
`sive property or privilege is claimed are defined as
`follows:
`1. A touch controlled electric switching circuit com-
`prising:
`
`4
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`

`4,731,548
`
`5
`a source of power for the actuation of a load to be
`selectively coupled to said source of power;
`a controllable means for selectively coupling said
`source to a load; and
`a control circuit including a series voltage divider
`input circuit including at least one capacitor having
`a first terminal connected to said source of power
`and an input touch terminal for coupling a person’s
`body capacitance in series with said at least one
`capacitor such that the voltage across said one
`capacitor produced by said source of power is
`changed when said input touch terminal is touched
`and said control circuit provides a control output
`signal in response to the touching of said touch
`terminal which signal is applied to said controllable
`means for selectively coupling said source of
`power to said load.
`2. The circuit as defined in claim 1 wherein said
`source of power is an alternating current source and
`wherein said controllable means comprises a first solid-
`state switch.
`
`3. The circuit as defined in claim 2 wherein said input
`circuit is coupled to said source of power and includes
`resistance means coupled in series between said touch
`terminal and said at least one capacitor.
`4. The circuit as defined in claim 3 wherein said resis-
`tance means comprises a pair of serially coupled resis-
`tors each having a resistance of at least 1 megaohm.
`5. A touch controlled electric switching circuit com-
`prising:
`a source of power for the actuation of a load to be
`selectively coupled to said source of power;
`a controllable means for selectively coupling said
`source to a load; and
`a control circuit including a series voltage divider
`input circuit including at least one capacitor and an
`input touch terminal for coupling a person’s body
`capacitance in series with said at least one capaci-
`tor such that the voltage between said one capaci-
`tor and said touch terminal
`is
`reduced when
`touched and said control circuit provides a control
`output signal in response to the touching of said
`touch terminal which signal is applied to said con-
`trollable means for selectively coupling said source-
`of power to said load, wherein said source of
`power is an alternating current source and wherein
`said controllable means comprises a first solid-state
`switch, wherein said input circuit is coupled to said
`source of power and includes resistance means
`coupled in series between said touch terminal and
`said at least one capacitor, wherein said resistance
`means comprises a pair of serially coupled resistors
`each having a resistance of at least 1 megaohm and,
`wherein the junction of said at least one capacitor
`and said resistance means is coupled to a control
`terminal of a second solid-state switch coupled to
`said power source and responsive to the change in
`capacitance and resulting voltage change at said
`junction to provide a controlling signal.
`6. The circuit as defined in claim 5 wherein said con-
`trol circuit further includes a logic circuit having an
`input terminal coupled to said second solid-state switch
`and output terminal coupled to said first solid-state
`switch, said logic circuit latching in response to succes-
`sive controlling signals for providing said control out-
`put signal.
`
`6
`7. The circuit as defined in claim 6 wherein said logic
`circuit comprises a squaring circuit serially coupled to a
`D-flip/flop circuit.
`8. A touch controlled electric switching circuit com-
`prising:
`a source of alternating current power for the actua-
`tion of a load to be selectively coupled to said
`source;
`a first solid-state switch for selectively coupling a
`load to said source and having a control input ter-
`minal for receiving control signals; and
`a control circuit including a touch plate responsive to
`the touch of an individual to provide a direct cur-
`rent control output signal applied to said control
`input terminal such that said first switch is ren-
`dered conductive during each half-cycle of each
`cycle of applied alternating current voltage,
`wherein said control circuit includes a series volt-
`age divider input circuit including said touch plate
`and at least one capacitor having a terminal remote
`from said touch plate connected to said source of
`alternating current power for coupling a person’s
`body capacitance in series with said at least one
`capacitor and said source of alternating current
`power such that said control circuit responds to the
`change in voltage across said one capacitor to se-
`lectively provide said direct current control signal.
`9. The circuit as defined in claim 8 wherein said input
`circuit is coupled to said source of power and includes
`resistance means coupled in series between said touch
`plate and said at least one capacitor.
`10. The circuit as defined in claim 9 wherein said
`resistance means comprises a pair of serially coupled
`resistors each having a resistance of at least 1 megohm.
`11. A touch controlled electronic switching circuit
`comprising:
`a source of alternating current power for the actua-
`tion of a load to be selectively coupled to said
`source;
`a first solid-state switch for selectively coupling a
`load to said source and having a control input ter-
`minal for receiving control signals; and
`a control circuit including a touch plate responsive to
`the touch of an individual to provide a direct cur-
`rent control output signal applied to said control
`input terminal such that said first switch is ren-
`dered conductive during each half-cycle of each
`cycle of applied alternating current voltage,
`wherein said control circuit includes a series volt~
`age divider input circuit including at least one ca-
`pacitor and said touch plate is coupled to said at
`least one capacitor for coupling a person’s body
`capacitance in series with said at least one capaci-
`tor such that said control circuit selectively pro-
`vides said direct current control signal, said source
`of power and includes resistance means coupled in
`series between said touch plate and said at least one
`capacitor, wherein said resistance means comprises
`a pair of serially coupled resistors each having a
`resistance of at least 1 megaohm and, wherein the
`junction of said at least one capacitor and said
`resistance means is coupled to a control terminal of
`a second solid-state switch coupled to said power
`source and responsive to the change in capacitance
`and resulting voltage change at said junction to
`provide a controlling signal.
`12. The circuit as defined in claim 11 wherein said
`control circuit further includes a logic circuit having an
`
`5
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`4,731,548
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`7
`8
`input terminal coupled to said second solid-state switch
`electrical power, said switch having a control input
`terminal; and
`and ouput
`terminal coupled to said first solid-state
`switch, said logic circuit latching in response to succes-
`a control circuit including an input circuit and a logic
`sive controlling signals for providing said control out—
`circuit for receiving tactile command information
`put signal.
`from an operator and for providing a control out-
`13. The circuit as defined in claim 12 wherein said
`put signal applied to said control input terminal of
`logic circuit comprises a squaring circuit serially cou-
`said solid-state switch, wherein said input circuit
`pled to a D-flip/flop circuit.
`includes a touch terminal coupled to at least one
`14. A touch controlled electrical switching circuit for
`capacitor having a terminal remote from said touch
`controlling power applied to a load, said circuit com-
`terminal coupled to the supply of power to define a
`prising:
`voltage divider circuity said input circuit further
`a solid-state switch and means for coupling said
`including resistance means coupled in series with
`switch between a load to be controlled and a sup-
`said touch terminal and said capacitor for limiting
`ply of electrical power, said switch having a con-
`current to said touch terminal, wherein said input
`trol input-terminal; and
`circuit further includes a second solid-state switch
`a control circuit including an input circuit and a logic
`having a control input terminal coupled to said
`circuit for receiving tactile command information
`touch terminal and to the supply of operating
`from an operator and for providing a control out-
`power and responsive to the touching of said touch
`put signal applied to said control input terminal of
`terminal for changing state.
`said solid-state switch, wherein said input circuit
`16. The circuit as defined in claim 15 wherein said
`includes a touch terminal coupled to at least one
`' control circuit further includes a logic circuit including
`capacitor having a terminal remote from said touch
`a latching circuit having an output terminal coupled to
`terminal coupled to the supply of power to define a
`said Control input terminal of said first named solid-state
`voltage divider circuit with a person’s body capaci-
`switch.
`tance, said input circuit further including resistance
`17. The circuit as defined in claim 16 wherein said
`means coupled in series with said touch terminal
`resistance means comprises a» pair of serially coupled
`and said capacitor for limiting current to said touch
`resistors each having a resistance of at least 1 megohm.
`terminal and voltage level responsive means re-
`18. The circuit as defined in claim 17 wherein said
`sponsive to said voltage divider circuit for causing
`logic circuit includes a squaring circuit coupled to said
`said logic circuit to change the state of said control
`, output signal.
`latching circuit and said latching circuit comprises a
`D-flip/flop circuit.
`15. A touch controlled electrical switching circuit for
`19. The electrical circuit as defined in claim 18
`controlling power applied to a load, said circuit com-
`prising:
`wherein said first named solid-state switch comprises a
`a solid-state switch and means for coupling said 35 Triac.
`*
`*
`it
`=3
`it
`switch between a load to be controlled and a supply of
`
`25
`
`30
`
`4s
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`50
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`55
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`65
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`6
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`

`

`
`
`UNITED STATES PATENT AND TRADEMARK OFFICE
`
`CERTIFICATE OF CORRECTION
`
`PATENTND.
`
`DATED
`
`:
`
`:
`
`4,731,543
`
`March 15, 1988
`
`|NVENTOR($ ;
`
`Ronald D. Ingraham
`
`It is certified that error appears in the above-identified patent and that said Letters Patent is hereby
`corrected asshovvn belovv:
`
`Commissioner of Patents and Trademarks
`
`line 56:
`Column 2,
`"terminal Al" should be -—terminal 51——
`Column 2,
`line 64:
`"shwon" should he —-shown—w
`
`line 56:
`Column 4,
`"controlled" should he -—controlling—~
`Column 6, claim 8, line 4:
`"electric" should be ——electronic--
`Column 6, claim 11,
`line 55:
`After "control signal" insert -—wherein said input circuit
`is coupled to——
`
`Signed and Sealed this
`
`Twenty-fifth Day of October, 1988
`
`Arresting Ofiicer
`
`DONALD J. QUIGG
`
`7
`
`