Matsushita Electric Works, Ltd.

Kazuhito Kayanoki

Muneo Suzuki

Hiroshi Matsuda

Tsunehiko Araki

Mikio Kondo

Yoshiaki Ueno

Akira Nagaoka

Makoto Morimoto

Yoshikazu Minakuchi

Masahiko Amano

Yoshihiro Tanikawa

Two-wire television interphone system is arranged to discriminate by a line voltage discriminator incorporated in a master device a line voltage variation due to a calling operation on the side of a branch device, to actuate a voltage controller in the branch device to shift the system from standby state to operation state, and to drive a call signal generator in the branch device for actuation of a call signal receiver in the master device. The system is thus made to have a power supply circuit energized for a power supply to the system only when required for effecting the calling operation, talking between the both devices, and so on.

Two-wire television interphone system

A passive infrared detector including an optical collector releasably attached to a base with a sensor on which incident infrared radiation directed through the optical collector is focused. The sensor is held by a joint member which is pivotally supported on the base and to which said optical collector is releasably attached, whereby the optical collector is rotatable together with the joint member relative to the base for adjustment of its angular position and the optical collector can be alone replaced as necessary without having to replace the base, the sensor and its associated electric circuitry.

Passive infrared detector

An object detecting apparatus has a plurality of light emitters which are sequentially actuated for projecting sequential light beams. A first structure is provided for receiving beams not reflected off any external body. A second structure is provided for receiving any part of the light beams reflected from an object in the area. A reference phase signal corresponding to the projected light beams is generated. A detection phase signal corresponding to the received reflected beam is also generated. The light emitters corresponding to the reflected light beams are continuously activated. The detection area is restricted by inhibition of output from an alarm phase difference discriminating circuit to a circuit when a difference between the reference and detection phases is not within a predetermined range. Consequently, the detection area can be restricted to a desired range, and the alarm circuit can be retained non-operative unless the object remains continuously in the area. This avoids any malfunction produced by any transitory object, while the actuation of the light projecting means in a very short time sequence accelerates the detecting operation with minimized power consumption.

Object detecting apparatus including photosensors for restricted

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Tsu, Japan

Kazuhito Kayanoki