| 摘要 |
PURPOSE:To make it possible to obtain rotary information in high reliability, by a method wherein light receiving element groups are arranged at 1/4 pitch intervals in the arrangement directions of slits and the output signals threfrom are compared with each other. CONSTITUTION:Four photodiodes Pd1-Pd4 are provided with respect to slits I1, I2... provided by drilling along the circumference of a rotor I0 so as to leave a constant pitch P between each adjacent slits and arranged at 1/4 pitch intervals in the arrangement directions of the slits I1, I2.... That is, because the photodiodes Pd1-Pd4 are provided in positional relation mutually shifted at every 1/4 pitch, the light receiving areas to incident light in mutual spaces therebetween also show 1/4 pitch shifted change and 90 deg. phase difference is generated between Pd1 and Pd2 while 180 deg. phase difference is generated between Pd1 and Pd3. Light currents Is1-Is4 outputted from the aforementioned Pd1-Pd4 are applied to input terminals of OP1-OP4 while the outputs therefrom are applied to comparators 1, 2 and outputs VoutA and VoutB are formed to obtain a signal having 90 deg. phase difference. From this signal, rotary information is obtained. |
