Patent ID: 7980553

Claim:
A method for measuring one or more dimensions of a stack of medium in a media input location of an imaging system, the method comprising the steps of: providing a media input location including a planar surface for receiving the stack of medium, the planar surface having a normal; providing a light source for emitting a beam of light along a direction that is at a predetermined angle with respect to the normal of the planar surface of the media input location; providing an array of photosensors disposed along an array direction that lies in a plane defined by the direction of the beam of light and the normal of the planar surface; providing a printing system controller; receiving a spatially-varying pattern of light in the photosensors of the photosensor array, the spatially-varying pattern of light having been reflected from a surface that is substantially parallel to the planar surface of the media input location, to provide corresponding electronic signal data from the photosensor array, the electronic signal data varying along the photosensor array; transmitting the varying electronic signal data to the printing system controller; using the varying electronic signal data to provide a measurement of the one or more dimensions corresponding to the stack of medium, wherein the one or more dimensions is a change in the height of the stack of medium; providing a media advance system to advance medium from the media input location along a media advance direction; emitting the beam of light from the light source to reflect off the first piece of medium; receiving the spatially varying pattern of light from the first piece of medium; transmitting the varying electronic signal corresponding to the first piece of medium to the printing system controller; advancing the first piece of medium to expose a second piece of medium to the beam of light; emitting the beam of light from the light source to reflect off the second piece of medium; receiving the spatially varying pattern of light from the second piece of medium; transmitting the varying electronic signal corresponding to the second piece of medium to the printing system controller; and comparing the varying electronic signal corresponding to the first piece of medium to the varying electronic signal corresponding to the second piece of medium to measure the change in the height of the stack of medium.