| 摘要 |
PURPOSE:To enable detection of a paper other than a designated one and prevent paper jamming or breakage of a thermal head from occurring, by providing a color forming layer of a thermal recording paper with a specified printing part and an effective printing part which are capable of forming different colors. CONSTITUTION:A thermal recording paper comprises an upper layer of a surface coating material 1, a color forming layer 2 as a black color forming intermediate layer, a lower layer of a base material and coating material 3, and a color forming layer 4 capable of forming a color (e.g., green) different form that of the color forming layer 2, the layer 4 being provided at the leading end of the recording paper and having a length of about 5cm. When heat is supplied from a thermal head to the thermal recording paper, for example, the green color forming layer 4 is caused to exude through the surface coating material 1 to form the green color. This color is detected by a reflection-type photosensor having a sensitivity varied depending on wavelength or other similar means, thereby checking whether the recording paper is a designated one. When the recording paper is not the designated one, energization of the thermal head is so controlled as to inhibit the subsequent printing. When the recording paper is the designated one, the thermal head is so controlled that the subsequent black color forming layer 2 will be effective for printing. |
