Hitachi, Ltd.

Nippon Oil Fats Co., Ltd.

Hitachi Automotive Engineering Co., Ltd.

Hitachi Tohbu Semiconductor, Ltd.

Hitachi Automotive Eng. Co., Ltd.

Harada Electronics Industry

Kunio Kobayashi

Keiichi Mashino

Masahide Harada

Tetsuaki Adachi

Tsuyoshi Shibuya

Keigo Naoi

Koji Ochi

Shouju Masumoto

Morio Satou

Osamu Miki

A mobile communication apparatus is provided, in which the linearity during a small output power of a radio-frequency power amplifier can be maintained as during a large output power. The input signal power to a radio-frequency power amplifier is decreased by an attenuator during a small power output. The resulting downward trend of the transmission signal power is compensated for by increasing the gain of the radio-frequency amplifier circuit through a transmission power control circuit. Under this condition, the radio-frequency power amplifier is made operable in a linear region of the transistor in the same manner as during a large power output. As a result, the linearity of the amplifier is guaranteed over the whole operating range of the transmission power.

Mobile communication apparatus and method

A delay circuit for use in an electric blasting system including a capacitor for storing electric energy supplied from an electric blaster, an actuation circuit for detecting the stop of voltage supply from the blaster to generate an actuation signal, a circuit for generating clock pulses, a circuit for counting a predetermined number of clock pulses in response to the actuation signal to generate an igniting signal, and a switching circuit for responding to the igniting signal to discharge the electric energy stored in the capacitor through an igniting resistor, the actuation circuit having a zener diode with a threshold voltage. When the voltage supply from the blaster is stopped and the voltage across the zener diode becomes lower than the threshold voltage, the zener diode is cut-off to generate the actuation signal.

Delay circuit for use in electric blasting system

A voltage regulator for a charging generator is disclosed which comprises an a.c. generator having armature windings and a field winding, and a battery which receives the rectified output of the a.c. generator and is charged by the same. The voltage regulator regulates the output voltage of the a.c. generator by controlling the current flowing through the field winding. To prevent the output voltage of the a.c. generator from becoming a high voltage when a connecting wire connecting the rectified output of the a.c. generator to the battery is broken, the regulator also includes an abnormality detection means which compares the rectified output of the a.c. generator with the battery voltage and detects the abnormality when both voltages are different by more than a predetermined value. This arrangement makes it possible to detect the abnormality at the point of time where the output voltage of the a.c. generator is not yet very high.

Voltage regulator for charging generator

A voltage regulator for a charging generator comprising an a.c. generator, a rectifier for converting the a.c. output of the a.c. generator to a d.c., a battery connected to the output of the rectifier, comparison means for comparing the battery voltage with a reference voltage of a reference voltage generation circuit and a power transistor controlled by the output of the comparison means and controlling a current flowing through a field coil of the a.c. generator. The reference voltage generation circuit comprises a voltage divider connected to a constant voltage power source and providing its divided voltage as the reference voltage, a plurality of transistors connected in parallel with a part of the voltage divider, and conduction control means for controlling the transistor in accordance with the ambient temperature so that the reference voltage is determined in accordance with the ambient temperature.

Growing community of inventors

Takasaki, Japan

Kunio Kobayashi