| 摘要 |
<p>PURPOSE:To sharpen the start-up of the optical output of a light emitting element and approximating the width of the on pulse of the optical output to the width of the pulse from a control signal input means by providing a resistance between the other electrode of a third transistor and the control electrode common junction between first and second transistors. CONSTITUTION:A resistance 10 is provided between the other electrode of a third transistor Q3 and the control electrode common junction between first and second transistors Q1 and Q2. Hereby, the potential of the control electrode of the third transistor Q3 becomes high by the amount of the voltage drop with the resistance, considering it on the basis of the control electrode common junction between the first and second transistors, and in case that the light emitting element shifts from OFF to ON, allowance occurs between the control electrode of the third transistor and the other electrode. As a result, in case that the light emitting element shifts from OFF to ON, the third transistor becomes late in turning to OFF, and the potential of the control electrode common junction between the first and second transistors rises sharply than ever, and the start-up of the driving current of the light emitting element is sharpened.</p> |
