초록 ▼

An automatic electrically powered dispenser for dispensing a product stored in the dispenser includes an active IR sensor system for detecting a user. The IR sensor system includes at least one IR emitter and at least one IR receiver. The IR sensing system is arranged to scan for the presence of a p

An automatic electrically powered dispenser for dispensing a product stored in the dispenser includes an active IR sensor system for detecting a user. The IR sensor system includes at least one IR emitter and at least one IR receiver. The IR sensing system is arranged to scan for the presence of a possible user at a certain scanning rate. A sensor control system supplies the active IR emitter(s) with a first current which is constant during one or more single scans and is altered to a different, second current for further scanning. The first and second currents are determined on the basis of a signal strength of the average received IR which is received by the IR receiver(s) during a number of previous single scans. In a simplified system, the average value of the most recently received IR values may be compared to a standard value set in the control system to alter the current supplied to the IR emitter(s).

대표청구항 ▼

The invention claimed is: 1. A dispenser for automatically dispensing a product stored in a product supply of said dispenser, said dispenser comprising an electric power supply and an active IR sensing system, said IR sensor system including at least one IR emitter and at least one IR receiver, whe

The invention claimed is: 1. A dispenser for automatically dispensing a product stored in a product supply of said dispenser, said dispenser comprising an electric power supply and an active IR sensing system, said IR sensor system including at least one IR emitter and at least one IR receiver, wherein said IR sensing system is arranged to scan for the presence of a possible user at least at a first scanning rate, and wherein a sensor control system is provided such that said active IR emitter is supplied with a first current which is substantially constant during one or more single scans but which can be altered to a different, second substantially constant current for further scanning, said first and second currents being determined on the basis of a signal strength of the average received IR which is received by said at least one IR receiver during a predetermined number of previous single scans, wherein said dispenser is a paper towel dispenser, and the sensor control system is arranged to detect a maximum threshold value of average received IR, upon which said sensor control system switches a dispensing mode of said dispenser from a user sensing mode to a hanging towel mode. 2. The dispenser according to claim 1, wherein said second current is made higher than said first current when the average IR received by said IR receiver increases from a first average received IR to a second higher average received IR, and is made lower than said first current when the average IR received by said IR receiver decreases from a first average received IR to a second lower average received IR. 3. The dispenser according to claim 1, wherein a first standard value Al has been set in the control circuitry, corresponding to a value of the expected detected signal strength received in normal operating conditions, and wherein the control system is arranged to calculate a moving average A2 of a predetermined number of the most recently received IR values, and when A2 >A1 the current supplied to the emitter is reduced, and in the case where A2 <Al, the current supplied to the emitters is increased. 4. The dispenser according to claim 1, wherein said predetermined number of previous single scans is between two and ten. 5. The dispenser according to claim 1, wherein said first current and said second current can be varied within fixed maximum and minimum limits. 6. The dispenser according to claim 5, wherein the maximum limit is between 10 and 150 greater than said minimum limit. 7. The dispenser according to claim 1, wherein said sensor system can also scan at a second scanning rate, and wherein said second scanning rate is higher than said first scanning rate, wherein the sensor system is arranged to change said scanning rate from said first scanning rate to said second scanning rate upon receiving a reflected IR level greater than a predetermined value above background IR level for a first predetermined number of single scans, and wherein said sensor system causes a product to be dispensed by said dispenser when said sensor system detects a change in received IR signal strength which is at or greater than a predetermined IR signal strength level above a background IR signal strength level for a second predetermined number of single scans. 8. The dispenser according to claim 7, wherein said predetermined signal strength level is at or above 10% higher than background. 9. The dispenser according to claim 1, wherein said sensor system comprises a plurality of IR receivers and at least one IR emitter, and the value of received IR values at all receivers is used to form a single average value of received IR during one single scan. 10. The dispenser according to claim 9, wherein said sensor system comprises at least two IR emitters and at least three IR receivers, wherein each emitter has one receiver on each lateral side thereof such that the emitters and receivers are in the order receiver-emitter-receiver -emitter-receiver in a lateral direction across the dispenser, and wherein the spacing between each emitter and each laterally adjacent receiver is substantially equal. 11. The dispenser according to claim 1, wherein said dispenser comprises a discharge outlet on or proximate a lower face thereof, and wherein each of said emitters and receivers is arranged on said lower face. 12. The dispenser according to claim 1, wherein said dispenser is a paper towel dispenser arranged to both store a supply of paper and to dispense at least a portion of said supply of paper. 13. The dispenser according to claim 1, wherein said IR emitters are controlled by a sensor control system to provide IR radiation to a level such that the detection field provided by said emitters is able to detect the presence of a possible user at a distance of up to 25 cm from said discharge outlet. 14. The dispenser according to claim 1, wherein said sensor system is arranged to emit IR radiation only with a first emitting frequency band and wherein said sensor system is arranged to detect radiation in a limited frequency detection range, wherein said first emitting frequency is about 15 kHz and said frequency detection range is between about 12 kHz and about 18 kHz. 15. The dispenser according to claim 1, wherein said sensor control system switches said dispensing mode from said hanging towel mode to said user sensing mode when the average received IR is measured to lie below said maximum threshold value. 16. The dispenser according to claim 15, wherein said control system is arranged with a time delay such that when the average received IR is measured to lie below said maximum threshold value said switching operation from said hanging towel mode to said user sensing mode is delayed for at least a first predetermined time. 17. The dispenser according to claim 16, wherein said first predetermined time is at least five seconds. 18. The dispenser according to claim 16, wherein said control system is arranged to prevent switching to said user sensing mode if within said first predetermined time, said maximum threshold value is exceeded. 19. The dispenser according to claim 15, wherein said control system is arranged to prevent switching to said user sensing mode if within said first predetermined time, said maximum threshold value is exceeded. 20. The dispenser according to claim 1, in which the average value of received IR is measured with the IR emitter turned off. 21. The dispenser according to claim 20, wherein the sensor control system is arranged such that when the average value of received IR with the IR emitter turned off is above 90% of the average value of received IR with the IR emitter turned on, a user sensing mode is disabled. 22. The dispenser according to claim 21, wherein said control system switches to a hanging towel mode after disabling the user sensing mode. 23. The dispenser according to claim 21, wherein said control system switches from said hanging towel mode back to said user-sensing mode, upon detecting that the average value of received IR with the IR emitter turned off is at or below 90% of the average value of received IR with the IR emitter turned on. 24. The dispenser according to claim 1, wherein a constant current sink is used to provide a constant current to the IR emitter.