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The invention is directed to improved automatic dispenser apparatus for dispensing sheet material and the like without contact between a user and the dispenser. Proximity detection apparatus is provided to detect the presence of a user in a detection zone generated outside the dispenser. Control app

The invention is directed to improved automatic dispenser apparatus for dispensing sheet material and the like without contact between a user and the dispenser. Proximity detection apparatus is provided to detect the presence of a user in a detection zone generated outside the dispenser. Control apparatus controls actuation of the dispenser in response to the detected user. Preferred forms of the proximity detector include a sensor and a signal detection circuit operatively connected to the sensor. The sensor includes conductors configured to have a capacitance and positioned such that the capacitance is changed by the presence of a user within the detection zone. The signal detection circuit detects the change in capacitance and is provided with an oscillator having a frequency which is affected by the sensor capacitance and a differential frequency discriminator which detects changes in the oscillator frequency. The control circuit receives the detected frequency change and generates a signal provided to actuate the dispenser to dispense the material.

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1. A dispenser apparatus for automatically dispensing sheet material without contact between a person and the dispenser, of the type including drive and tension rollers which are rotatably mounted with respect to the dispenser and which form a nip therebetween through which the sheet material is fed

1. A dispenser apparatus for automatically dispensing sheet material without contact between a person and the dispenser, of the type including drive and tension rollers which are rotatably mounted with respect to the dispenser and which form a nip therebetween through which the sheet material is fed, motor drive apparatus in power transmission relationship with the drive roller and power supply apparatus providing electrical current to the motor drive and dispenser electrical components, the improvement comprising:a sensor secured with respect to the dispenser, said sensor having first and second conductors configured to have a capacitance and positioned such that the capacitance is changed by the presence of a user within a detection zone projecting outwardly from the dispenser; a signal detection circuit operatively connected to the sensor for detecting the capacitance change, such circuit having (1) an oscillator having a frequency which is affected by the sensor capacitance, and (2) a differential frequency discriminator which detects changes in the oscillator frequency; and a control circuit which receives the detected frequency change and actuates the motor drive apparatus to dispense the sheet material. 2. The apparatus of claim 1 wherein the differential frequency discriminator includes:a signal conditioning circuit configured to produce: (1) a first series of pulses, each pulse being of fixed duration and the series of pulses having a frequency corresponding to the oscillator frequency; and (2) a second series of pulses, such second series being the complement of the first series; a first averaging circuit the output of which is a first average, such first average being the average of the first series of pulses; a second averaging circuit the output of which is a second average, such second average being the average of the second series of pulses; and a first comparator which compares the first average and the second average and produces an output which is a discriminator difference multiplied by a gain factor of the first comparator, such discriminator difference being the difference between the second average and the first average, and such output corresponds to the presence of the user within the detection zone. 3. The apparatus of claim 2 wherein the frequency discriminatory further includes a set point circuit which sets the discriminator difference substantially to zero when the user is not present in the detection zone.4. The apparatus of claim 3 wherein the signal conditioning circuit includes a monostable multivibrator and the multivibrator generates the first and second series of pulses.5. The apparatus of claim 2 wherein the signal detection circuit further includes circuitry for setting a detection zone volume, wherein:the signal detection circuit generates a predetermined threshold reference signal provided to set the detection zone volume; the signal detection circuit includes a second comparator which (1) compares the output of the first comparator with the threshold reference signal and (2) provides an output which is the difference between the threshold reference signal and the output from the first comparator, such difference being multiplied by a gain factor of the second comparator; and the detection zone volume is expanded and contracted by changing the threshold reference signal. 6. The apparatus of claim 1 wherein the sensor has a three-dimensional geometry and the sensor three-dimensional geometry generates a generally arcuate detection zone projecting outwardly from the dispenser.7. The apparatus of claim 6 wherein the three-dimensional sensor includes a substrate having a three-dimensional geometry and wherein the first and second conductors are deposited on the substrate, each conductor having a three-dimensional geometry conforming to that of the substrate.8. The apparatus of claim 1 wherein:the first conductor comprises a first plurality of parallel conductor elements on a substrate and connected such that each element of the first plurality is conductively connected to every other element in the first plurality; and the second conductor comprises a second plurality of parallel conductor elements on the substrate and connected such that each element of the second plurality is conductively connected to every other element in the second plurality. 9. The apparatus of claim 8 wherein the elements of the first plurality and the elements of the second plurality are substantially parallel to each other and the nearest element to each element in the first plurality is an element of the second plurality and the nearest element to each element in the second plurality is an element of the first plurality.10. The apparatus of claim 1 wherein the control circuit includes a timer controller which sets a minimum time duration of a capacitance change required to actuate the dispenser.11. The apparatus of claim 10 wherein the control circuit further includes a blocking controller which limits dispenser actuation to a single cycle for each detected capacitance change.12. The apparatus of claim 11 wherein the control circuit comprises a programmable controller including preprogrammed instructions, and the programmable controller comprises the timer and blocking controllers.13. The apparatus of claim 1 further including a power supply voltage compensation circuit which provides a reference voltage proportional to a power supply voltage and controls the duration of motor drive actuation such that the dispensing of sheet material is substantially independent of changes in the power supply voltage.14. The apparatus of claim 1 wherein the control circuit includes a sheet material length selector comprising:a control for selecting one of several sheet material lengths to be dispensed; a length signal corresponding to the selected control setting; two or more preset length reference signals corresponding to preselected lengths of sheet material to be dispensed; and a sheet length comparator which compares the length signal with the preset length reference signals to determine which sheet material length has been selected. 15. The apparatus of claim 14 wherein the control circuit comprises a programmable controller including preprogrammed instructions, and wherein the programmable controller includes the preset length reference signals and the sheet length comparator.16. The apparatus of claim 1 further including a low-power-supply alarm which includes:a first preset voltage level; a second preset voltage level; a power-warning comparator which compares the power supply voltage to the first and second preset voltage levels; an indicator which provides a warning signal when the power supply voltage is below the first preset voltage level; and a lockout circuit which blocks the dispensing of sheet material when the power supply voltage is below the second preset voltage level. 17. The apparatus of claim 16 wherein the control circuit comprises a programmable controller including preprogrammed instructions, and the low-power-supply alarm is included in the programmable controller.18. A dispenser apparatus for automatically dispensing a web of sheet material, without contact between a person and the dispenser comprising:drive and tension rollers which are rotatably mounted with respect to the dispenser and which form a nip therebetween through which the sheet material is fed out of the dispenser; motor drive apparatus in power-transmission relationship with the drive roller to rotate the drive roller and feed the sheet material through the nip; power supply apparatus providing electrical current to the motor drive apparatus and to electrical components of the dispenser; a sensor secured with respect to the dispenser and having first and second conductors, said conductors configured to have a capacitance and positioned such that the capacitance is changed by the presence of a user within a shaped detection zone generated by the sensor, such detection zone projecting outwardly from the dispenser; a signal detection circuit operatively connected to the sensor, the detection circuit detecting the capacitance change and having (1) an oscillator with a frequency which is affected by the sensor capacitance, and (2) a differential frequency discriminator which detects changes in the oscillator frequency, such frequency discriminator including: (a) a signal conditioning circuit configured to produce: (I) a first series of pulses, each pulse being of fixed duration and the series of pulses having a frequency corresponding to the oscillator frequency; and (ii) a second series of pulses, such second series being the complement of the first series; (b) a first averaging circuit the output of which is a first average, such first average being the average of the first series of pulses; (c) a second averaging circuit the output of which is a second average, such second average being the average of the second series of pulses; (d) a first comparator which compares the first average and the second average and produces an output which is a discriminator difference multiplied by a gain factor of the first comparator, such discriminator difference being the difference between the second average and the first average, and such output corresponds to the presence of the user within the detection zone; and (e) a set point circuit which sets the discriminator difference substantially to zero when the user is not present in the detection zone; and a control circuit which receives the detected frequency change and actuates the motor drive apparatus to dispense the sheet material in response thereto. 19. The apparatus of claim 18 wherein the signal conditioning circuit includes a monostable multivibrator and the multivibrator generates the first and second series of pulses.20. The apparatus of claim 18 wherein the signal detection circuit further includes circuitry for setting a detection zone volume, wherein:the signal detection circuit generates a predetermined threshold reference signal provided to set the detection zone volume; the signal detection circuit includes a second comparator which (1) compares the output of the first comparator with the threshold reference signal and (2) provides an output which is the difference between the threshold reference signal and the output from the first comparator, such difference being multiplied by a gain factor of the second comparator; and the detection zone volume is expanded and contracted by changing the threshold reference signal. 21. The apparatus of claim 18 wherein the sensor is a three-dimensional sensor and the sensor includes a substrate having a three-dimensional geometry and wherein the first and second conductors are deposited on the substrate, each conductor having a three-dimensional geometry conforming to that of the substrate.22. The apparatus of claim 21 wherein:the first conductor comprises a first plurality of parallel conductor elements deposited on the substrate and connected such that each element of the first plurality is conductively connected to every other element in the first plurality; and the second conductor comprises a second plurality of parallel conductor elements deposited on the substrate and connected such that each element of the second plurality is conductively connected to every other element in the second plurality. 23. The apparatus of claim 22 wherein the elements of the first plurality and the elements of the second plurality are substantially parallel to each other and the nearest element to each element in the first plurality is an element of the second plurality and the nearest element to each element in the second plurality is an element of the first plurality.24. The apparatus of claim 18 wherein the control circuit includes a timer controller which sets a minimum time duration of a capacitance change required to actuate the dispenser.25. The apparatus of claim 24 wherein the control circuit further includes a blocking controller which limits dispenser actuation to a single cycle for each detected capacitance change.26. The apparatus of claim 25 wherein the control circuit comprises a programmable controller including preprogrammed instructions, and the programmable controller comprises the timer and blocking controllers.27. The apparatus of claim 18 further including a power supply voltage compensation circuit which provides a reference voltage proportional to a power supply voltage and controls the duration of motor drive actuation such that the dispensing of sheet material is substantially independent of changes in the power supply voltage.28. The apparatus of claim 18 wherein the control circuit includes a sheet material length selector comprising:a control for selecting one of several sheet material lengths to be dispensed; a length signal corresponding to the selected control setting; two or more preset length reference signals corresponding to preselected lengths of sheet material to be dispensed; and a sheet length comparator which compares the length signal with the preset length reference signals to determine which sheet material length has been selected. 29. The apparatus of claim 28 wherein the control circuit comprises a programmable controller including preprogrammed instructions, and wherein the programmable controller includes the preset length reference signals and the sheet length comparator.30. The apparatus of claim 18 further including a low-power-supply alarm which includes:a first preset voltage level; a second preset voltage level; a power-warning comparator which compares the power supply voltage to the first and second preset voltage levels; an indicator which provides a warning signal when the power supply voltage is below the first preset voltage level; and a lockout circuit which blocks the dispensing of sheet material when the power supply voltage is below the second preset voltage level. 31. The apparatus of claim 30 wherein the control circuit comprises a programmable controller including preprogrammed instructions, and the low-power-supply alarm is included in the programmable controller.32. Automatic dispenser apparatus for dispensing product therefrom without contact between a user and the dispenser comprising:a housing; storage apparatus within the housing storing the product; automatic discharge apparatus within the housing, said discharge apparatus receiving the stored product and discharging the product from the housing in response to a drive signal; a sensor in the housing having first and second conductors configured to have a capacitance and positioned such that the capacitance is changed by the presence of a user within a detection zone projecting outwardly from the sensor; a signal detection circuit in the housing operatively connected to the sensor for detecting the capacitance change, such circuit having (1) an oscillator which generates a frequency which is affected by the sensor capacitance, and (2) a differential frequency discriminator which detects changes in the oscillator frequency; a control circuit in the housing operatively connected to the signal detection circuit and discharge apparatus, said control circuit being configured to receive the detected frequency change and generate the drive signal actuating the discharge apparatus; and power supply apparatus providing electrical power to the discharge apparatus and the signal detection and control circuits. 33. The apparatus of claim 32 wherein the differential frequency discriminator includes:a signal conditioning circuit configured to produce: (1) a first series of pulses, each pulse being of fixed duration and the series of pulses having a frequency corresponding to the oscillator frequency; and (2) a second series of pulses, such second series being the complement of the first series; a first averaging circuit the output of which is a first average, such first average being the average of the first series of pulses; a second averaging circuit the output of which is a second average, such second average being the average of the second series of pulses; and a first comparator which compares the first average and the second average and produces an output which is a discriminator difference multiplied by a gain factor of the first comparator, such discriminator difference being the difference between the second average and the first average, and such output corresponds to the presence of the user within the detection zone. 34. The apparatus of claim 33 further including a set point circuit which sets the discriminator difference substantially to zero when the user is not present in the detection zone.35. The apparatus of claim 34 wherein the signal conditioning circuit includes a monostable multivibrator and the multivibrator generates the first and second series of pulses.36. The apparatus of claim 33 wherein the signal detection circuit further includes circuitry for setting a detection zone volume, wherein:the signal detection circuit generates a predetermined threshold reference signal provided to set the detection zone volume; the signal detection circuit includes a second comparator which (1) compares the output of the first comparator with the threshold reference signal and (2) provides an output which is the difference between the threshold reference signal and the output from the first comparator, such difference being multiplied by a gain factor of the second comparator; and the detection zone volume is expanded and contracted by changing the threshold reference signal. 37. The apparatus of claim 33 wherein the sensor has a three-dimensional geometry and the sensor three-dimensional geometry generates a generally arcuate detection zone projecting outwardly from the apparatus.38. The apparatus of claim 37 wherein the three-dimensional sensor includes a substrate having a three-dimensional geometry and wherein the first and second conductors are deposited on the substrate, each conductor having a three-dimensional geometry conforming to that of the substrate.39. The apparatus of claim 33 wherein the control circuit includes a timer controller which sets a minimum time duration of a capacitance change required to actuate the dispenser.40. The apparatus of claim 39 wherein the control circuit further includes a blocking controller which limits dispenser actuation to a single dispensing cycle for each detected capacitance change.41. The apparatus of claim 40 wherein the control circuit comprises a programmable controller including preprogrammed instructions, and the programmable controller comprises the timer and blocking controllers.42. The apparatus of claim 33 further including a power supply voltage compensation circuit which provides a reference voltage proportional to a power supply voltage and controls the duration of dispenser actuation such that the dispenser actuation is substantially independent of changes in the power supply voltage.43. The apparatus of claim 33 wherein the control circuit controls the amount of product dispensed and comprises:a control for selecting one of several product amounts to be dispensed; a product amount signal corresponding to the selected control setting; two or more preset amount reference signals corresponding to preselected amounts of product to be dispensed; and a product amount comparator which compares the amount signal with the preset amount reference signals to determine which product amount has been selected. 44. The apparatus of claim 43 wherein the control circuit comprises a programmable controller including preprogrammed instructions, and wherein the programmable controller includes the preset amount reference signals and the product amount comparator.45. The apparatus of claim 33 further including a low-power-supply alarm which includes:a first preset voltage level; a second preset voltage level; a power-warning comparator which compares the power supply voltage to the first and second preset voltage levels; an indicator which provides a warning signal when the power supply voltage is below the first preset voltage level; and a lockout circuit which blocks the dispensing of product when the power supply voltage is below the second preset voltage level. 46. The apparatus of claim 45 wherein the control circuit comprises a programmable controller including preprogrammed instructions, and the low-power-supply alarm is included in the programmable controller.47. The apparatus of claim 32 wherein:the first conductor comprises a first plurality of parallel conductor elements on a substrate and connected such that each element of the first plurality is conductively connected to every other element in the first plurality; and the second conductor comprises a second plurality of parallel conductor elements on the substrate and connected such that each element of the second plurality is conductively connected to every other element in the second plurality. 48. The apparatus of claim 47 wherein the elements of the first plurality and the elements of the second plurality are substantially parallel to each other and the nearest element to each element in the first plurality is an element of the second plurality and the nearest element to each element in the second plurality is an element of the first plurality.