Omron Tateisi Electronics Co.

Omron Corporation

Hirofumi Endo

Yasushi Matsuoka

Satoshi Motouji

Yoshimi Kanda

Akio Matsumoto

Tsutomu Ajioka

Hidetoshi Matsumoto

Koji Ohmori

Yutaka Nozaki

In a switching circuit formed as an integrated circuit, a series circuit comprising a diode (D.sub.1) and a resistor (R.sub.1) is connected between a base and an emitter of an npn transistor (TR.sub.1) requiring a high speed switching operation. Therefore, a high speed operation is made possible. Furthermore, in a circuit constructed such that the above npn transistor is driven by a pnp transistor (TR.sub.3, TR.sub.4), a leakage current produced in the above pnp transistor at high temperature is allowed to flow in the above series circuit. Accordingly, a malfunction of the above npn transistor is prevented. Consequently, an integrated circuit operable even under high temperatures is achieved.

Transistor switching circuit having diode-resistor in base of transistor

An oscillation circuit of a proximity switch includes a parallel LC resonance circuit (L, C), an oscillation transistor (Tr6) controlled by an output voltage from the resonance circuit for switching a constant current and a feedback circuit (Tr2, Tr3) for feeding back a current flowing through the oscillation transistor to the resonance circuit. In the circuit, there is further disposed a feedback current increase circuit including a second transistor (Tr7) controlled by an output voltage from the resonance circuit and a resistor (R) connected in series to the second transistor. The resonance circuit is supplied via the feedback circuit with a feedback current obtained by adding a current flowing through the feedback current increase circuit and a current passing through the oscillation transistor, thereby developing a large change in the amplitude of the oscillation.

Oscillation circuit for proximity switch

The present invention is directed to a motor rotation speed controlling apparatus including a comparator, a detecting circuit for detecting a feedback signal of a motor, a motor driving transistor, and a circuit for changing the level of a constant voltage fed to the comparator. The comparator compares a saw-tooth voltage with a constant voltage and outputs a signal which has a duty cycle corresponding to the result of the comparison. The motor driving transistor drives the motor in response to the output signal from the comparator. To change the duty cycle of the output signal from the comparator, a circuit is used that changes the level of the constant voltage in response to a feedback signal detected by the detecting circuit.

Motor rotation speed controlling apparatus

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Nagaokakyo, Japan

Hirofumi Endo