| 摘要 |
PURPOSE:To prevent a thermosensitive recording head from temperature rising, by substituting a part of image signals, to be applied, with an unheating signal in response to the temperature of the thermosensitive recording head. CONSTITUTION:If the temperature of a thermosensitive recording head 1 rises for some reason, a signal S1 from a thermistor 4 increases and reaches a certain level in due time. At this time, an output signal S2 from a comparater 6 is converted into ''H'' to activated a NAND gate 8. In an output from the NAND gate 8, a signal S4 from T-FF 7 appears as a reversed signal S5. An image signal S6 comes in the state whose AND is taken off at an AND gate 9 by the signal S5. That is, the black signal part of the image signal S6 is periodically converted into ''L'' by a signal produced by reverse of the signal S4 from T-FF 7, i.e. substituted with a white signal. Consequently, the density of the black signal in the image signal is lowered, to reduce a heat amount to be generated in the thermosensitive recording head 1, to stop the temperature rising and to start temperature falling. |
