| 摘要 |
PURPOSE:To verify the presence of a form accurately by providing carriers in both the inside and outside areas of a platen with optical sensors followed by the comparison of outputs from them. CONSTITUTION:Output signals from optical sensors 4 and 5 installed on a carrier 3 are converted into digital signals by means of AD converters 6 and 7, and then are compared by a comparison circuit 8. The optical sensor 4 is set within the form area on a platen 2, and the optical sensor 5 is set in the outside of the form area. When the form 1 is on the platen 2, even if it is a colored form similar to the color of the platen 2, and even if the reflect power of the form 1 varies depending on surrounding temperature, as signals from the optical sensors 4 and 5 are differently outputted, the comparison circuit 8 allows the difference in signal to be outputted as a positive signal that the form is available. When no form 1 is on the platen 2, the comparison circuit 8 allows the signal to be outputted as a negative one that no form is available.
|
