Patent ID: 6443546
Filing Date: 2002-09-03
Classification: B41J

Abstract:
A printing apparatus for supplying ink from an ink tank, the ink tank including a prism formed on a predetermined one of a plurality of walls constituting the ink tank used for optically detecting whether or not ink is present, and further including a light-reflecting surface used for optically detecting whether or not the ink tank is present, said printing apparatus performing printing using a printhead according to an ink-jet method, said apparatus comprising:a light-emitting unit emitting light to at least one of the prism and the light-reflecting surface; a light-receiving unit receiving light; difference calculating means for calculating a difference between a first signal, which is obtained from light received by said light-receiving unit in a case where said light-emitting unit emits the light, and a second signal, which is obtained from light received by said light-receiving unit in a case where said light-emitting unit emits no light; judgment means for judging whether or not ink is present, or whether or not the ink tank is present, based upon the difference calculated by said difference calculating means, wherein said judgment means includes comparison means for comparing the difference obtained by said difference calculating means with a predetermined threshold value, and wherein said judgment means judges whether or not ink is present, or whether or not the ink tank is present, based on result of comparison by said comparison means.