PURPOSE: To dispose a switch circuit to a base plate directry by constituting a switch circuit for impressing an electric source individually against a plurarity of common lines for a power supply for a control under a partition of an electric current flow of a heat generation resistance body with an electric field transistor.
CONSTITUTION: The heat generation resistance body which is divided into two blocks in every two bits is provided to a heat generation body shift resistor driver 31. The one block is connected to a first common line C1, and a common line C1 is connected in common to each source terminal of an electric field transistor 33a composing a switch circuit. The other block is connected to a second common line C2, and a common line C2 is connected in common to each source terminal of an electric field transistor 33b composing the switch circuit. The heat generation of this switch circuit is little, and the former can be driven in high speed, and mounted to a thermal head base plate directly.
YAMAMOTO TADASHI
INUI TETSUYUKI
