Matsushita Electric Industrial Co., Ltd.

Kouichi Yamada

Tatsuo Wada

Toshiomi Yabu

Tadashi Yoshino

Kiyoshi Takeda

Tatsuo Mizota

Kunio Aoki

Masaru Hashirano

A tape speed control system for a multiple speed tape recording and reproducing apparatus comprising a transducer head for reproducing a tape speed indicative signal which has been recorded along an edge of a recording tape. The frequency of the reproduced speed indicative signal is compared with a plurality of reference values to determine to which one of separate frequency bands the frequency of the reproduced speed signal belongs. If the latter belongs to the frequency band other than the frequency band which includes a predetermined frequency derived when the playback speed equals to the recording speed, a corresponding motor drive signal is generated to vary the speed of the tape until the frequency of the reproduced speed signal reaches the predetermined frequency.

Speed control system for a multiple speed tape recording and reproducing

A magnetic tape recording and reproducing apparatus provided with means for recording a cue-signal which serves to mark a predetermined point of a magnetic tape on which video signals are recorded by a rotary magnetic head. The cue-signal is recorded by a full erasing head by supplying thereto a cue-signal current having a frequency lower than the frequency of the erasing current. For example, the cue-signal current is generated by using the control signal for synchronizing the rotation of the rotary head with the tape movement.

Magnetic recording and reproducing apparatus having means for recording

This invention relates to a speed control circuit of a d.c. motor having a frequency generator. To the conventional method in which a rotation detection signal is delayed by a monostable multivibrator circuit and this delayed signal and the rotation detection signal are gated to obtain a speed error signal, a new time-voltage converter circuit is added, whereby even if the detected frequency of the generator is low, a stable speed control is possible. Because of no error synchronization, the present speed control circuit is suited to an apparatus which requires speed switching, and also to semiconductor integration.

Speed control circuit

A sawtooth wave forming circuit has an input signal alternately applied to the bases of first and a second transistors forming a differential amplifier, and a circuit which permits flow of a current equal to or proportional to the current flowing in the collector of the first transistor is connected between the differential amplifier and a power source. A capacitor is provided between ground and the junction between the circuit and differential amplifier. With this arrangement, the charge-discharge cycle of the capacitor is controlled by means of the input signal. By making use of the sawtooth wave forming circuit constituted in this way, stable trapezoidal or triangular waves having only small fluctuations in the slopes of the sides of the wave can be formed.

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Higashiosaka, Japan

Kouichi Yamada