Maeda Metal Industries, Ltd.

Takayoshi Obatake

Toshihiko Kushida

Yasunobu Kaneyama

Shozo Matsumura

Yukio Torigai

Tatsuo Hirai

In an electric tool, in order to carry out a phase control or an antiphase control using a transistor, constant voltage generating means of the tool includes a series circuit including a resistor and a diode, and a parallel circuit including a capacitor and a Zener diode. One end of the resistor is connected between an AC power supply and an AC motor. A cathode of the diode is connected to one capacitor end and a cathode of the Zener diode. The other capacitor end and an anode of the Zener diode are connected to transistor sources. One ends of resistors are connected to gates of the transistors, and a voltage at the other ends of the resistors are switched between a voltage at a node between the series circuit and the parallel circuit and a voltage of the source of the transistors to turn the transistors ON or OFF.

Electric tool

A phase control apparatus includes a first transistor whose source or emitter is connected to one end of an AC power supply and whose drain or collector is connected to one end of a load, a second transistor whose source or emitter is connected to the other end of the AC supply and whose drain or collector is connected to the other end of the load, a diode bridge that rectifies an AC voltage of the AC supply, and a parallel circuit of a zener diode and a capacitor. The parallel circuit generates a high potential relative to a bridge negative output terminal potential, or generates a low potential relative to a bridge positive output terminal potential. First and second transistor control terminal potentials are switched between the high and the bridge negative output terminal potentials, or between the low and the bridge positive output terminal potentials.

Phase control apparatus

There is provided a wireless data transmitting and receiving system that wirelessly transmits a signal regarding a torque acting on a rotary shaft and/or a rotation angle of the rotary shaft from a data transmitting unit disposed in the rotary shaft to a data receiving unit. The wireless data transmitting and receiving system includes: a data transmitting unit () provided on the rotary shaft () of a tightening machine () to detect the torque and the rotation angle, the data transmitting unit () including a torque sensor () disposed so as to be capable of sensing a toque acting on the rotary shaft (), a rotation angle sensor () disposed so as to be capable of a rotation angle of the rotary shaft (), and transmitting means () that is electrically connected to the foregoing sensors (), and wirelessly transmits signals regarding the torque detected in the torque sensor () and the rotation angle detected in the rotation angle sensor (); and a data receiving unit () including receiving means () that receives the transmitted signals regarding the torque and the rotation angle, and display means () that displays the signals regarding the torque and the rotation angle received by the receiving means ().

Wireless data transmitting and receiving system

An antenna switching method of a wireless communication system capable of efficiently transmitting various signals from a plurality of transmitting antennas to a receiving unit is provided. The method includes a received signal intensity measuring step of operating an antenna switch () and obtaining received signal intensities of all the transmitting antennas (), a step of comparing the obtained received signal intensities of all the transmitting antennas and determining a transmitting antenna wherein the received signal intensity is the highest, a step of operating the antenna switch so that the transmitting antenna wherein the received signal intensity is the highest is connected to a transmitting circuitand fixing the transmitting antenna, and a step of transmitting signals thereafter from the transmitting circuit via the fixed transmitting antenna.

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Nishinomiya, Japan

Takayoshi Obatake