| 摘要 |
A pulse generating mechanism for a photosensitive web-roll (31), mounted for rotation within a light-tight cartridge (10), comprises a flange (22) on the web-roll (31): a plurality of activating means (44, 46) on the flange (22) that are equally spaced angularly from each other and radially from the flange center; and sensing means (58) disposed outside the cartridge (10) for sensing movement of each activating means (44, 46) therepast, upon incremental rotation of the flange (22) and web-roll (31), and for generating pulses in response to said sensing for monitoring quantity of web remaining on the web-roll (31). Each activating means (44, 46) preferably comprises a ferromagnetic or electrically conductive element (44) on the flange (22), and the sensing means (58) preferably comprises a transducer (58) for sensing presence of that element (44). The element (44) may comprise a ferromagnetic or electrically conductive disc (50) thereon affixed to the flange (22) or spaced bosses (44) on a flange made of ferromagnetic or electrically conductive material. |
