| 摘要 |
PURPOSE:To obtain an inexpensive sheet detector having a simple construction, by a method wherein a part of a conductor in an electric current supplying loop of a thermal head is exposed, and the presence or absence of a printing sheet between the head and a platen is detected in terms of the presence or absence of electrical conduction between the exposed part and a contact provided on the platen side. CONSTITUTION:In the thermal head 10, a resistor is vapor deposited on a substrate to form heating elements 12, and the surfaces of the elements 12 are not coated with an electrically insulating material. The head 10 is brought into contact with the platen 11 made of an electrically conductive material such as an electrically conductive rubber, and printing is performed by inserting the sheet therebetween. The presnece or absence of the sheet between the elements 12 and the platen 11 is detected in terms of the presence or absence of electrical conduction between terminals A and B which make contact with the elements 12 and the platen 11, respectively. |
