| 摘要 |
PURPOSE:To realize three-lead wire constitution by connecting two photodetecting elements of a pickup cartridge, provided whth a photosensor unit, together in series through a variable resistance and by leading an output from its variable resistance. CONSTITUTION:In a photosensor unit circuit consisting of one light emitting element and two photodetecting elements, two photodetecting elements PT1 and PT2 receiving reflected light from the light emitting element L on a nosound groove zone are connected in series via a variable resistance VR1. Then, a detection output Vout is led out from the VR1, which is then adjusted so that the Vout is zero, thus correcting the position shift of a stylus tip from a reflected light point. Consequently, the number of lead wires is one less than that of a conventional unit and while seven-lead-wire constitution for a pickup cartridge is realized, the position shift of the stylus tip position from the reflected light point is corrected. |
