Copal Company Limited

Copal Electronics Co., Ltd.

Teiichi Shimane

Hiroshi Takano

A drive and control circuit for laser diodes includes: a first switching element connected in series to a laser diode connected to a constant-current source for actuating the laser diode when a binary drive signal is at one level thereof; an impedance element connected in parallel to the series circuit of the laser diode and the first switching element, the impedance element being connected to receive the constant-current source together with the laser diode and having impedance characteristics substantially equal to those of the laser diode and the constant-current source; an integrator circuit for integrating the data at the one level; an impedance control circuit for variably controlling the impedance of the impedance element in response to the integrator circuit; and a second switching element connected in series to the impedance element for actuating the impedance element when the drive signal is at the other level. Furthermore, an alternative embodiment of the drive and control circuit includes the combination of a comparator, an integrator circuit, a constant-current circuit, a counter and a timer.

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Tokyo, Japan

Teiichi Shimane