Device for driving thermal head

Abstract

Abstract PURPOSE:To control power supplied to thermal heads irrespective of characteristics of detecting elements or a change thereof, by a device wherein a change in temperature of a head base is output as a change of electric resistance in a digital signal and this output signal is converted to drive the head with the corresponding time width. CONSTITUTION:A thermistor 1 attached to a base of a thermal head is connected to an operational amplifier 2. When output of the amplifier 2 assumes H and a start pulse from a terminal 16 assumes L, an AND gate 8 is opened by output from inverter and a latch circuit 7 is driven to latch output of a counter 5. An ROM9 includes a conversion table for generating proper outputs D0-D7 by referring outputs from the latch circuit 7 as addresses. Outputs 1Q-8Q of a latch circuit 10 are connected to switch elements 11a-11h of a switch circuit 11, respectively. Operation of each of those switch elements can vary a resistance value which determines a time constant of a monostable multivibrator 12.

Inventors

• 👤 Minoru Ogata
• 👤 Masahiro Sakamoto

Bibliographic Details