PURPOSE: To make production easy and to detect the position of an optical head with a high precision by securing a minute gap between an auxiliary slit and a reference slit easily and accurately with the forming precision of a frame body.
CONSTITUTION: An auxiliary slit 26a is formed on an auxiliary slit plate 19 of an encoder, and the outside periphery is held by a frame body 45, and many reference slits 24 are formed on a reference slit plate 18. The auxiliary slit plate 19 is placed on the upper face of the reference slit plate 18 and on both sides of reference slits 24 by lower face of both sides of the frame body 45 to raise the auxiliary slit 26a a minute gap G from reference slits 24 by the height of projecting parts 50. A light emitting element and a photodetecting element are arranged above and below both slits plates, and the auxiliary slit plate 19 is slid relatively on the upper face of the reference slit plate 18, and the light from the light emitting element is received interruptedly by the photodetecting element to generate a pulse voltage.
TAKI RYOJI
SUZUKI TAMOTSU
| JPS557649A | 1980-01-19 |