Balance with scale zero setting by motor - is controlled by photoelectric switching element mounted on balance pointer

摘要

The rotation of the motor is controlled by a photoelectric switching element in the motor supply circuit. The photoelectric switching element (7) and the corresponding light source (6) are mounted on the pointer (1, 5). The light path to the photo-electric switching element can be interrupted by a screen on the scale (3) which can be moved in one direction. Interruption of the photoelectric element (7) illumination by the light source (6) interrupts the current supply to the light source (6) and to the photoelectric element (7).