Abstract: In a photoelectric converter-type pulse encoder comprising a light-entrance portion (13, 13'), a rotating slit plate (12) on which a lattice plate receiving light from the light-entrance portion (13, 13') is formed, a fixed slit plate (11) on which a lattice plate arranged to face the lattice plate of the rotating slit plate is formed, and a light-receiving portion (14, 14') arranged below the fixed slit plate, light is emitted from a light-emitting circuit to the light-entrance portion (13, 13') through the light fibers (17), and the light received by the light-receiving portion (14, 14') is introduced into a light-receiving circuit through the light fibers (17), thereby adjustment of the amount of light is made easier, the pulse generation in response to the rotating speed is ensured, and the rotating speed is detected with a high precision.

Abstract: In an LED light source device for a pulse encoder, a plurality of LEDs are divided into a plurality of groups and each of said groups is included in one of the branches connected across the power source. At least one dummy LED or dummy diode is connected in series with the LED in a predetermined one of said branches, so that the voltage drop characteristics of said branches are equalized.