Pioneer Electronic Corporation

Hitachi, Ltd.

Yoshiyuki Takizawa

Takashi Kashiwazaki

Akira Haeno

Yasuo Kominami

Tomomitsu Takano

Norihiko Itoh

Junji Kobayashi

Kazuo Watanabe

Tetsuo Sato

Kazumi Kuriyama

Akira Motoyama

Koki Aizawa

Koji Shimoda

A pickup level control device for a system for reading out recorded information which has a pickup element producing a pickup output signal. The device detects a dc component of the pickup output signal and produces a level control signal. A voltage level of the pickup output signal is controlled in response to the level control signal produced by the dc level detection operation. The control of the voltage level of the pickup output signal is performed by a variable impedance element connected to a terminal of the pickup element, so that a peak level of an ac component of the pickup output signal is controlled below a predetermined level.

Pickup level control device for a system for reading out recorded

An amplifier circuit has an operational amplifier and a negative feedback circuit. An input signal is applied to the non-inverting input terminal of the operational amplifier, whereby a first output signal is provided from the output terminal of the operational amplifier. The first output signal is fed back to the inverting input terminal of the operational amplifier through the negative feedback circuit. The negative feedback signal of the negative feedback circuit is fed back to the inverting input terminal through an impedance converter. Thus, a second output signal of low distortion factor is derived from the output terminal of the impedance converter.

Amplifier circuit

A noise reduction system is provided which can operate as either a Dolby B-type or C-type system. In either case, an input signal is applied to the variable impedance of a high-level side chain through an identical shared filter circuit network. The high-level side chain has two voltage-current converters for controlling the variable impedance. By substantially inhibiting the operation of one of the two converters, the system operates as a C-type Dolby system. On the other hand, when the system operates as a B-type Dolby system, a bias current is applied to each of the two converters during periods of no input signal. This bias current is about half of a minute bias control current which is applied during no signal periods to the single converter used when the system operates as the C-type Dolby system.

Noise reduction system

A tape drive control system for a pinch roller-less type tape recorder in which tape drive is implemented by frictional force between the capstan and tape. A mode instruction circuit determines the operational mode of a capstan motor drive circuit which operates a capstan motor which in turn rotates the conveying capstan. Tape run detection means detects the actual tape condition. The mode instruction circuit operates both in response to outputs of the tape run detection means and to switch inputs to control the operational mode of the capstan drive.

Tape drive control system for pinch roller-less type tape recorder

A device for detecting non-recorded portions on a magnetic tape including a circuit for preventing malfunctions in the detecting device. The output from a playback head of a tape recorder is amplified then passed through a malfunction preventing circuit which passes the signal if its amplitude is above a preset level for at least a predetermined period of time. The output signal from the malfunction preventing circuit is waveform shaped then rectified and passed through a charge/discharge circuit to a solenoid energizing circuit. The malfunction preventing circuit includes a variable impedance element such as a field effect transistor coupled between an output terminal of the circuit and ground with the impedance of the element varied in accordance with the magnitude of the input signal with a delay added. The waveform shaping circuit, the rectifying circuit and the charge/discharge circuit convert the output of the malfunction preventing circuit into a switching waveform used to control a solenoid which sets the tape speed of the tape recorder such that the tape is run fast when no signal is present on the tape.

Device for detecting non-recorded portions on magnetic tape

A friction force drive capstan tape recorder having movable arms to tension a tape between an idler and a drive capstan. The displacement of the arms is sensed to provide an input signal to a control circuit to vary the rotational torque of the take-up reel motor. This closed loop system allows constant tension to be maintained on the tape and the sensing of the end of the tape. Freely rotatable tape shifters are provided to minimize tension loss. The movable arms are outwardly displaceable to facilitate tape loading by means of a gear train coupled to the operating lever. At the same time the rollers are displaced to facilitate tape handling. A switch may be coupled to the operating lever to provide power to the system or cut it off.

Growing community of inventors

Tokorozawa, Japan

Yoshiyuki Takizawa