Printer media feed encoder apparatus and method
AssigneeHewlett-Packard Development Company, L.P.
InventorsRichard A. Kelley, Bruce G. Johnson
Life of this patent
Estimating the term…
Abstract
A printer with a media feed apparatus bas a media tray with a surface for supporting a media stack. A wave drive mechanism has a pair of wheels, a belt looped around said wheels, and a plurality of freewheeling rollers. Each one of the freewheeling rollers has an axis attached to and moving with the belt. At least one of the plurality of freewheeling rollers makes contact with the top sheet in the tray while the belt moves the axis in a feed direction to shift the top sheet in the feed direction. A controller controls a bias force of the wave drive mechanism against the top sheet during the time that the wave drive mechanism moves the sheet.
Claims14
A printer with a media feed apparatus comprising:
- a media tray having a support surface for supporting a media stack;
- a feed roller for receiving a top sheet of the media stack;
- a wave drive mechanism comprising a pair of wheels, a belt looped around said wheels, and a plurality of freewheeling rollers, each one of said freewheeling rollers having an axis attached to and moving with the belt, wherein at least one of the plurality of freewheeling rollers makes contact with the top sheet in the tray while the belt moves said axis in a feed direction to shift the top sheet in the feed direction;
- and
- a controller controlling a bias force of the wave drive mechanism against the top sheet during said time that the wave drive mechanism moves the sheet.
A method of individuating a top sheet from a stack of media comprising:
- shifting the top sheet in a feed direction with a wave guide mechanism to move the top sheet into a position to be picked from the media stack, wherein the wave guide mechanism comprises a pair of spaced apart wheels, a belt looped around the wheels, and a plurality of freewheeling rollers, each one of said freewheeling rollers having an axis attached to and moving with the belt, wherein at least one of the plurality of rollers makes contact with the top sheet while the belt moves the axis of said at least one freewheeling roller;
- picking the top sheet from the media stack;
- monitoring the motion of the sheet during shifting prior to picking;
- and
- in response to monitoring, controlling a bias force of the wave drive mechanism against the top sheet to maintain a rate of movement of the sheet above a preselected threshold during said shifting.
A media sheet feed apparatus comprising:
- a media tray having an upper media stack support surface suitable for supporting a stack of media;
- a wave drive mechanism comprising a pair of spaced apart wheels, a belt looped around the spaced apart wheels, and a plurality of freewheeling rollers, each one of said freewheeling rollers having an axis attached to and moving with the belt, wherein at least one of the plurality of freewheeling rollers makes contact with the stack while the belt moves the axis of said at least one freewheeling roller in a feed direction to shift a current top sheet of the stack into a position to be picked from the media stack;
- a picking mechanism which picks the shifted top sheet;
- a motion encoder above the tray operable to detect motion of the top sheet at least during a time while the wave drive mechanism moves the sheet prior to the sheet being picked by the picking mechanism;
- and
- a controller connected to the encoder and the wave drive mechanism, and operable to maintain a rate of sheet movement, while the sheet is being shifted, above a preselected threshold prior to said picking by increasing the bias force of the wave drive mechanism.
Dependencies are inferred from the claim text.