Position detection encoder having plural light receiving and light emitting elements

DETAILED DESCRIPTION Accordingly, the present invention has been developed with a view to substantially eliminating the above discussed drawbacks inherent in the prior art, and has for its essential object to provide an improved encoder.
Another important object of the present invention is to provide a improved encoder of the type referred to above, where a plurality of light emitting elements and light receiving elements are provided, stable detection signals are provided if the error factors are provided on the code plate when the detection signals having the phase difference are obtained, also, the size may be made smaller when the coded patterns are used.
In accomplishing these and other objects, according to a first embodiment of the present invention, there is provided an encoder including a light emitting element, a code plate with slits formed therein, a light receiving element a plurality of signals having a phase difference may be provided by a plurality of light emitting elements and light receiving elements a pair of light emitting elements are disposed approximately oppositely to each other on both the sides of the code plate, a pair of light receiving elements corresponding to these light emitting elements are respectively arranged on the opposite sides of the code plate and in approximate opposition to each other so that a pair of detection signals having the phase difference may be obtained with the lights passing through the same slit.
Also, according to a second embodiment of the present invention, there is provided an encoder including with a code plate having coded patterns formed of a plurality of slits thereon, and a plurality of light emitting elements and light receiving elements disposed opposite to each other on both the sides of the code plate in accordance with the respective coded patterns.
The light emitting element and the light receiving element are disposed alternately on both the sides of the code plate, and the light emitting element and the light receiving element are disposed oppositely to each other with a code plate being grasped therebetween