| 摘要 |
PURPOSE:To prevent the jam of transfer paper from being induced and make a transfer paper size detector small in size and inexpensive by detecting the size of transfer paper by making use of a roller pair which is used for conveyance of transfer paper and is revolving under pressure contact. CONSTITUTION:Piezoelectric rubber 14 which generates electromotive force by depending on pressure, a retainer 15, a compression coil spring 16 etc. are provided to the rod 11 of a feed roller unit 1. When transfer paper is conveyed by the unit 1 and is inserted between a pair of rollers 3, 8, the lower roller 8 is pushed down against the spring 16 and is pressed; therefore the pressing force thereof is propagated to the rubber 14, and this results in increased electromotive force. When this electromotive force exceeds a reference voltage, pulses are generated, and according to the number of these pulses, the size of the transfer paper is detected. Hence, there is no need for providing various switches in the image supporting conveyance path, and the induction of the jam of an image supporting body is obviated. |
