| 摘要 |
PURPOSE:To optically detect the size of a diameter of a rolled paper by disposing irradiating means for applying light to the peripheral surface of the rolled paper and photo detecting means for receiving light irradiated by the irradiating means. CONSTITUTION:A lamp 3 is disposed adjacent to one side of a rolled paper 1 of a copier or a facsimile, and a lot of photodiodes 4 are arranged adjacent to the other side of the rolled paper 1. When the rolled paper 1 goes to the minimum diameter, the last photodiode 4X is operated, so that the photodiode connected to the diode 4X is caused to emit light, and an alarm lamp is lighted to inform that the rolled paper 1 has to be replaced. Thus, the residual quantity of the rolled paper 1 can be detected reliably. |
