Electronic Dispenser

End User/Market: Commercial Facilities

Background:

A battery operated, electronically controlled paper towel dispenser must accurately dispense a pre-determined length of paper towel. The dispensing action is controlled by a brush-type DC motor. Battery voltage variation affects motor RPM which degrades the accuracy of the length of the dispensed sheet.

Opportunity:

Develop novel, inexpensive method to accurately control dispenser sheet length.

Solution:

Measure motor current flowing through a sense resistor. Use microcontroller A/D convertor to periodically sample motor current signal. Extract motor rotation information, from sampled motor current signal, with digital signal processing algorithms. Control motor rotation to accurately dispense a predetermined length of paper towel.

Results:

Electronic dispenser with inexpensive, sensor-less, accurate paper length control. One US patent.

Technologies:

MSP430F2012 microcontroller, A/D convertor, C firmware, schematic capture, circuit board layout, VB.NET test software.