PURPOSE: To enable the detection of information on motor rotation by obtaining two sets each of reverse phase signals with the rotation of a rotary plate from two photoelectric conversion means comprising photoelectric conversion elements separated radially over the entire periphery and electrodes for electrically connecting the elements.
CONSTITUTION: Light from a flat light source 13 is shielded with a rotary plate 14 while irradiating a first photoelectric conversion element 19b and 19a alternately through a first slit 17a of the rotary plate 14 and hence, it is allowed to irradiate the conversion elements 19a and 19b in the opposite phase to each other. This light is applied to an arithmetic amplifier and a photoelectro-motive current-voltage conversion circuit to obtain voltages Va and Vb in the elements 19a and 19b in proportion to the quantity of irradiated light. The voltages Va and Vb are opposite in the phase. When these voltages are applied to a differential amplification circuit, they cancel noises of the same phase as those to increase signals thereby producing signals with a high signal-noise ratio. This enables accurate detection of information on the motor rotation.
OZAWA KUNIKAZU
NAKASE HIROKI
KOUNO SHINYA
| JPS5412872A | 1979-01-30 | |||
| JP55148642B | ||||
| JPS49129841A | 1974-12-12 |
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