Victor Company of Japan, Limited

Tomohiro Mori

Yoshiaki Tanaka

Mamoru Inami

Zenju Ohtsuki

Akio Hasegawa

An automatic recording bias current setting apparatus comprises a bias current generating circuit for generating a bias current with varied level of the bias current, a testing signal generating circuit for generating two kinds of testing signals having different mid and high frequencies of an audio signal, by independently varying the levels of the testing signals, a recording and reproducing circuit for recording the two kinds of testing signals with the bias current onto a magnetic recording medium and reproducing the same, and a bias current detecting circuit for detecting the level of a bias current. The recording and reproducing circuit repeats an operation in which the two kinds of testing signals are recorded onto the magnetic recording medium and then reproduced with independently varied levels of the two kinds of testing signals under the same bias current obtained from the bias current generating circuit, for each of the different varied bias currents. The bias current detecting circuit detects respective reproduced output levels of the two kinds of testing signals with respect to the different bias currents, to detect a bias current level at a point where a difference between respective maximum reproduced output levels becomes equal to a preset predetermined value.

Automatic recording bias current setting apparatus

A code generating apparatus comprises an oscillator for continuously producing a sinusoidal wave which has a constant frequency, a square wave generating circuit supplied with the output sinusoidal wave of the oscillator, for generating first and second square waves having period which is twice the period of the sinusoidal wave, where the first and second square waves having mutually inverted phases, a code transmitting circuit pre-stored with a code which is to be generated, as a bit sequence, for alternately transmitting through first and second output terminals thereof the bit sequence in terms of one bit in phase with the first or second square wave, a switching signal producing circuit for producing a switch signal from a combination of the first and second square waves and output signals from the first and second output terminals of the code transmitting circuit, and a switching circuit controlled in response to the switching signal from the switching signal producing circuit, for selectively and intermittently producing through a code output terminal thereof the output sinusoidal wave of the oscillator as the code.

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Maebashi, Japan

Tomohiro Mori