Automatic dispenser apparatus

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.

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.