| 摘要 |
PURPOSE:To shorten a time required for adjusting luminous energy by a delay circuit by providing a plurality of the delay circuits of different time constant and a limit circuit, and adjusting the luminous energy of a light source by an output signal of the limit circuit. CONSTITUTION:When a quantity of emitted light of a recording light source 7 is detected by a light receiving diode 1, a detection signal is amplified by an amplifier 2 to apply a sample hold by predetermined timing in a sample hold circuit 3. After voltage of the sample hold is compared with the reference voltage in a comparator circuit 4, a compared result is delayed by the first delay circuit 5a to stabilize a fluctuation of the compared result moderated, and further a limit of voltage is applied in a limit circuit 6. Thus, the quantity of emitted light of the light source 7 can be determined by an output signal of the limit circuit 6. In the case of changing the quantity of emitted light of the recording light source 7, the second delay circuit 5b of different time constant is used. In this way, shortening of a luminous energy fluctuation time is contrived while obtaining stable luminous energy at recording time. |
