Abstract: A temperature control system has a light intensity detection device for providing temperature compensation in accordance with the variation in angle of incident sunlight. The light intensity detection device includes a photoelectric device having a light receiving surface and which produces an electrical output signal in accordance with the intensity of received light. An optical device is disposed between a light source and the light receiving surface. Incident light transmitted through the optical device is re-directed to the light receiving surface by a plurality of prism surfaces disposed on the optical device facing the photoelectric device. The prism surfaces may be concentrically arranged around the optical axis of the photoelectric device.

Abstract: An automobile differential gear system capable of establishing an appropriate differential motion between the right and left driving axles of an automobile so that the automobile is able to run smoothly along a curve where the right and left driving axles are required to be driven at different revolving rates respectively. The system comprises a differential gear, a steering angle detecting unit for detecting a steering angle, a driving speed detecting unit for detecting the speed of the differential gear case, a pinion speed control unit which provides a control signal for controlling the differential motion of the right and left driving axles of the automobile, and a pinion driving unit for rotating the pinions to control the respective revolving rates of the right and left driving axles according to the control signal so that correct and quick response of the movement of the automobile to steering operation is achieved.