Pioneer Electronic Corporation

Alps Electric Co., Ltd.

Hideki Fujimoto

Akira Nishioka

Yoshihiro Kawanabe

Hiroyuki Takahori

Fumihisa Hori

Mikio Miyajima

Kohsaki Yanata

Fujio Sasaki

An apparatus for detecting frequency response of audio signals of left and right channels. The audio signals of the left and right channels are alternately introduced at a predetermined periodic rate with intervals of a predetermined duration between times of signal introduction, the introduced audio signals are detected after being divided into a plurality of frequency band signals by band-pass filters, and one of the detected outputs is in turn relayed selectively. During the above described intervals of predetermined duration, an output end of detection device is grounded and the gain of the band-pass filters are made substantially equal to zero in synchronism with the timing of the grounding.

Frequency response detection apparatus

A voltage/current conversion circuit giving an output current which is proportional to an input voltage. The circuit includes an operational amplifier to one input of which the input voltage is applied, first and second transistors, to the commonly connected bases of which the output of the operational amplifier is applied, and a feed-back path connecting the collector of the first transistor to the other input of the operational amplifier. With the circuit thus constructed, the output derived from the collector of the second transistor is in proportion to the input voltage.

Voltage/current conversion circuit

A voltage controlled attenuator includes a control circuit having variable impedance means whose impedance varies in a stepwise fashion as an input voltage is varied. In this manner, the attenuation characteristic of the attenuator can be made to vary stepwise in slope or inclination to improve its efficacy for use as a volume control device in audio apparatus.

Control circuit for voltage controlled variable attenuator

In an endless inked ribbon cartridge wherein an inked ribbon received in a chamber is drawn out from the receiving chamber by a guide arm and then fed into the receiving chamber by another guide arm, and the inked ribbon is exposed between the guide arms for printing, a guide plate is disposed which covers the exposed inked ribbon except a part necessary for printing, thereby to prevent the inked ribbon from staining fingers or paper and from severing accidentally.

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Tokyo, Japan

Hideki Fujimoto