| 摘要 |
PURPOSE:To enable high-speed and reliable detection without being affected by humidity and other external conditions, by a method wherein a heat source, a reflection surface, a first pivotable mirror which obliquely irradiates with a radiation light, and a second pivotable mirror, which transmits a reflection light to a light- receiving part, are installed. CONSTITUTION:A reflection plate 20 is placed on the way of a conveyance path for a transfer sheet 12, which is an object to be measured, and a heat source 22 and a first mirror 23, which obliquely irradiates the reflection surface of the reflection plate with a light, are mounted at the upstream side of a conveyance direction. The first mirror 23 reflects the reflection light 24, and a light-receiving part 33, in which light-receiving elements, such as photodiodes, are situated, receives a reflection light 29 from the reflection plate 20 through a second mirror 30 and a light-collecting lens 31. The first and the second mirrors 23 and 30, consisting of, for example, galvanomirror, are positioned so that they can reciprocate at a given rotary angle at a mirror drive circuit. This permits the high-speed and reliable detection of sheet thickness, regardless of the sheet form shape of the object. |
