| 摘要 |
PURPOSE:To obtain a monitoring signal which is easily processed and to reduce power consumption by providing a shaping circuit which shapes the waveform of a signal monitoring the movement extent of a lens, and a power source circuit which supplies electric power to the shaping circuit. CONSTITUTION:A power source connection terminal 1 and a grounding terminal 2 are connected to a power source on a camera side or in a lens. A driving command signal to a lens driving motor is inputted to signal input terminals 3 and 4. A transistor (TR) 6 and a resistance 7 form the power source circuit 8 and a source voltage VCC is supplied to a light emission diode 10. The diode 10 projects light upon a code plate 12 and a code plate 11 has light and dark parts alternately and is fitted to a distance ring or lens driving gear. A photodiode 12 photodetects reflected light from the code plate 11 and generates the monitoring signal for the movement extent of the lens. The monitoring signal is supplied to a frequency dividing circuit 16 through the waveform shaping circuit 15 consisting of an operational amplifier 13 and a resistance 14 and frequency-divided by a zoom ratio signal S. Thus, the frequency division is performed accurately and the power consumption is reduced. |
