Paper thickness sensor in a printer
View Patent ↗A pagewidth drop on demand printer includes a printhead having an array of fixed printing nozzles thereon. A platen ( 14 ) having a platen surface upon which a sheet rides to receive ink from the printing nozzles is situated alongside the nozzles. A sensor ( 88 ) is provided to measure an offset of the print surface of the sheet with respect to the printing nozzles and means is provided effecting movement of the platen to alter the offset. This is typically done by making a compensatory rotation of the platen.
1. A pagewidth printer comprising:
a printhead having an array of fixed printing nozzles thereon,
a platen having a platen surface upon which a sheet rides to receive on a print surface thereof ink from said printing nozzles,
an optical sensor to measure an offset of said print surface with respect to said printing nozzles, and
means to effect movement of said platen to alter said offset
wherein the optical sensor senses the position of a pivotal sensor flat that engages the print surface and wherein wherein the sensor flag is mounted upon a spring-biased pivotal shaft mounted to the printhead.
2. The pagewidth printer of claim 1 wherein said platen is mounted so as to rotate about a longitudinal axis thereof and said platen surface extends along the platen parallel with said axis at a non-constant distance from said axis such that compensatory rotation of the platen effects the offset of said print surface with respect to said printing nozzles.