| 摘要 |
PURPOSE:To make a platen roller separatable from a thermal head when power source is being disconnected without complicating the constitution by placing a pressurizing means under a pressure released condition in response to the output of a detecting means when power source of a printer is being connected. CONSTITUTION:On a platen roller 1, clamp claws 2 which clamp one end edge of a transfer paper are provided, and at the same time, a thermal head 3 is confront-arranged to the outer peripheral surface. It is controlled in such a manner that when a pressurizing position sensor 20 is located on a longer diameter semicircular part 17, and light is obstructed, pressure is released by rotating a motor counterclockwise, and when the sensor 20 detects transmitted light, after the sensor 20 is placed under a shaded condition at a shoulder part 16b on the larger diameter semicircular part 17 by rotating the motor 13 clockwise, the motor 13 is stopped to place the thermal head under a pressure released condition. As the result, the thermal head 3 is always migrated to the pressure released condition when power source is being connected, and therefore, even when the power source is disconnected during printing, at the time when the power source is turned on, the thermal head 3 can be separated without being damaged by the clamp claws 2 on the platen. |
