| 摘要 |
PURPOSE:To form an encoder output with high reliability by a simple circuit configuration, by forming an output signal for movement information of a substance from an output of the second photodetecting element, in accordance with the basis of an output of the first photodetecting element for a monitor. CONSTITUTION:In accordance with the basis of an output of the first photodetecting element PD1 for a monitor to which a light beam from a light emission element L is always provided, and an output signal for movement information of a substance is formed from an output of the second photodetecting element PD2 to which a light beam from the same light emission element L is made incident intermittently through a moving substance. For instance, an output of an operational amplifier OP1 is led out as an output for providing a thershold level Vth by use of a ciruit as shown in the figure, so that a digital output signal Va of a low levle and a high level in the state that an input signal Vao of a relevant comparator Comp is higher than the thershold level Vth, and in the state that it is lower than the threshold level Vth, respectively. |
