JPS624903Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention supports a rotating head on a rotor with a piezoelectric element, and displaces the rotating head by applying a control signal such as a sawtooth wave to the piezoelectric element. The present invention relates to a video head position control device for a VTR that compensates for tracking errors that occur when performing special playback such as , still, and slow playback.

[Conventional technology]

Conventionally, in this type of VTR, when transmitting control signals such as sawtooth waves generated on the stator to the piezoelectric elements on the rotor, a rotary transformer channel separate from the rotary transformer channel for video signal transmission is used. Signals were transmitted by adding additional devices or by installing slip rings, etc.

[Problem that the invention attempts to solve]

When transmitting control signals such as sawtooth waves generated on the stator to the piezoelectric elements on the rotor as described above, it is necessary to add a rotary transformer channel separate from the rotary transformer channel for video signal transmission, or Devices that transmit signals by providing a slip ring or the like have the drawbacks of increasing the product price and hindering miniaturization.

This invention was made in order to eliminate the drawbacks of the conventional devices as described above, and it is possible to position the video head without requiring a dedicated rotary transformer channel or slip ring for transmitting the piezoelectric element control signal. The purpose is to provide a control device.

[Means for solving problems]

This invention, as a means to solve such problems, uses the control signal of the piezoelectric element to amplitude modulate a carrier wave set at a low frequency band outside the video signal band, and multiplexes this onto the video signal to generate a video signal. The signals are transmitted onto the rotor through the same channel of the rotary transformer for signal transmission. LPF mounted on the rotor
The components of the control signal are extracted, rectified and demodulated, and applied to the piezoelectric element.

[Operation] In this invention, a control signal such as a sawtooth wave generated by a printed circuit board or the like is frequency multiplexed into a low frequency band outside the video signal band, and the channel of the rotary transformer used to transmit the video signal is multiplexed. Pass it through this as well. In this way, the control signal described above is transmitted from the stator to the piezoelectric element on the rotor. The piezoelectric element on the rotor is then displaced in response to the control signal. The piezoelectric element supports a rotating head and is capable of imparting the required displacement to the rotating head.

As described above, tracking errors that occur when performing special playback such as stills and slows are compensated for.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. In the figure, numeral 1 denotes a detector, which outputs a signal indicating in which direction the rotating head has deviated from the normal scanning trace, or a signal corresponding to the magnitude of the deviation. Such a detector is well known, and its configuration is not directly related to the present invention, so a detailed explanation will be omitted. Reference numeral 2 denotes an oscillator, which outputs a signal with a lower frequency than the video signal. 3
is an amplitude modulator, and the output of the oscillator 2 is amplitude-modulated by the output (control signal) of the detector 1. The amplitude-modulated control signal is amplified by an amplifier 4 and supplied to a rectifier circuit 6 installed in a well-known drum assembly 5 via a rotary transformer 7, the channel of which has already been used for video signal transmission. It is also used for the same purpose. That is, control signals frequency-multiplexed in a low frequency band outside the video signal band are passed through the same channel of the rotary transformer 7. Then, a control signal and a video signal are respectively taken out from the secondary side of the rotary transformer 7 by an LPF and an HPF.

The control signal extracted through the LPF is passed through the rectifier circuit 6 and applied to the piezoelectric element 8. The rotating head also directs the video signal through the HPF.

[Effect of idea]

In the present invention, the rotary head on the rotor is supported by a piezoelectric element, and by applying a control signal to the piezoelectric element and displacing the rotary head, the rotary head is displaced in a direction different from the direction of rotation. This is a position control device for a rotary head in a VTR designed to compensate for tracking errors that occur when special playback is performed. comprising an amplitude modulator that performs amplitude modulation according to a control signal, an LPF, and a rectifier, and contactlessly transmits the output of the amplitude modulator onto the rotor through a channel of a rotary transformer for transmitting video signals;
The control signal is demodulated by extracting the output of the amplitude modulator via the LPF on the rotor and passing it through the rectifier, and the control signal is applied to the piezoelectric element. The position of the rotary head can be controlled without adding a conventional channel of a rotary transformer for video signal transmission.

[Brief explanation of the drawing]

The figure is a block diagram showing one embodiment of the present invention. 1: Detector, 2: Oscillator, 3: Amplitude modulator,
4: Amplifier, 5: Drum assembly, 6: Rectifier circuit, 7: Rotary transformer, 8: Piezoelectric element.

Claims (1)

[Scope of utility model registration request] A rotating head on a rotor is supported by a piezoelectric element, and by applying a control signal to the piezoelectric element and displacing it, the rotating head is displaced in a direction different from the direction of rotation, and special reproduction such as steel and slow is performed. This is a position control device for a rotary head in a VTR designed to compensate for tracking errors that occur during tracking. an amplitude modulator that modulates the amplitude;
The output of the amplitude modulator is transmitted contactlessly onto the rotor through a channel of a rotary transformer for video signal transmission, and the output of the amplitude modulator is transmitted on the rotor via the LPF. A position control device for a rotary head in a VTR, characterized in that the control signal is extracted and passed through the rectifier to demodulate the control signal, and the control signal is applied to the piezoelectric element.