A powered dispenser for dispensing individual sheet segments from a
continuous roll of sheet material provided with spaced tear lines
comprises a powered feed mechanism, a releasable, powered drive mechanism,
a powered transfer mechanism, a pair of web sensing sensors, a capacitive
sensing system providing automatic sensitivity adjustment, and control
circuitry. A dual power supply system provides a mechanical lock-out
functionality, and the control system is protected from electrostatic
build-up on the surface of the feed roller. The web sensor, and an antenna
plate of the capacitive sensing system, are provided on respective printed
circuit boards mounted in overlying relation. Utilizing signals received
from the pair of web sensors and the capacitive sensing system, the
control circuitry senses the presence of a user to activate the powered
drive mechanism, and prevents further dispensing of the sheet material
until a previously dispensed segment is separated from the roll. The web
sensors detection of a leading edge of the sheet material initiates a
predetermined interval of sheet material advancement providing a proper
placement of successive tear lines. Various approaches may be utilized to
accommodate inadvertent sheet "tabbing" scenarios. The web sensors,
together with the control circuitry, are also used to detect the
depletion, or absence, of a working roll of sheet material, whereupon the
control circuitry controls the powered transfer mechanism to automatically
transfer the web feed supply from a depleted working roll to a reserve
roll. The powered transfer mechanism may include a motor driven transfer
bar, or provide motor driven release of a spring biased transfer bar.
Another arrangement allows for ready release of a roll core, and drop of
the same into an open dispenser cover for removal.