Sharp Kabushiki Kaisha Corporation

Hiromu Itoh

Kenji Hachimura

Zempei Tani

Junichiro Kikunaga

Tatsuya Kato

A light sensitive switching circuit for automatically controlling the supply of electric power from a power source to a load, such as a lantern, is disclosed. When it becomes darker than a predetermined brightness the power supply starts and when it becomes bright again, the power supply is cut. The light sensitive switching circuit comprises first and second lines for connecting the power source and the load in series between the first and second lines. A first thyristor is connected between the first and second lines, and a second thyristor connected is to the first thyristor such that the anode of the second thyristor is connected to the gate of the first thyristor and the cathode of the second thyristor is connected to the cathode of the first thyristor. A photocell is connected between the gate and the cathode of the second thyristor.

Light sensitive switching circuit

A D.C. motor position control system operates either in the motor speed detection mode or in the motor position detection mode. A rotary encoder develops an approximate sinusoidal position indicating analog signal in response to the rotation of the D.C. motor. A waveform shaping circuit receives the approximate sinusoidal position indicating analog signal and develops a rectangular position indicating digital signal to a phase comparator which compares the phase of the rectangular position indicating digital signal with the phase of a speed instructing pulse signal so as to control the motor speed in a phase-locked-loop (PLL) manner in the motor speed detection mode. A slice level determination circuit divides the voltage level of the approximate sinusoidal position indicating analog signal into 16 (sixteen) degrees to obtain a sliced position indicating digital signal which is used to control the motor position in the motor position detection mode.

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Nara, Japan

Hiromu Itoh