| 摘要 |
A print head driving circuit is provided whereby, even if the load changes, the accuracy of the driving voltage waveform supplied to the load can be maintained, and consequently, deterioration in printing quality can be prevented. Transistors Q 3 , Q 4 connected in a push-pull configuration are connected to the upstream of a transistor Q 1 . If the base potential of the transistor Q 1 rises above its normal level, then the emitter potential of the transistors Q 3 , Q 4 will rise and the transistor Q 3 will become non-conductive, and the transistor Q 1 will also become non-conductive, but since the transistor Q 4 is conductive, the current I<SUB>2 </SUB>will flow from the base terminal of the transistor Q 1 , to earth, via the transistor Q 4 , and hence the base potential of the transistor Q 1 will fall to or below the prescribed value. As a result, it is possible to prevent the base potential of the transistor Q 1 from rising up in excess of the prescribed value.
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