JPS6045925A - Rotary cylinder device - Google Patents

Abstract

PURPOSE:To simplify the position control of a head by sticking ring-like piezo- electric thin plates to one side or both sides of a ring-like metallic thin plate concentrically to form a stick type driving element. CONSTITUTION:A rotary cylinder device has the ring-like piezo-electric magnetic thin plates 1, 1' and the ring-like metallic thin plate 2. The piezo-electric magnetic plates 1, 1' are sticked to the metallic thin plate 2 so that upper and lower electrode-removed parts are positioned. The driving element 2 is fixed on a rotary cylinder 8 by a fixing means 7 and formed so as to press the metallic thin plate part 2. This invention adopts the ring-like stick type driving element as a head driving element and fixes the metallic plate part on the circumferential part of the driving element, so that the position of the leading end of the peripheral part is stabilized and position control can be simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a rotating cylinder device for a helical scan type video tape recorder (hereinafter abbreviated as VTR).

Conventional configuration and its problems In a helical scan type VTR, one field is recorded on one track. Therefore, video signal recording is synchronized using a vertical synchronization signal, and the control signal and video signal are recorded on the magnetic tape. During playback, synchronization is performed using the control signal, and recording is performed using a head with the same azimuth as the recording head. Noise-free reproduced images are obtained by tracing the tracks.

However, during special playback such as static, low-speed, and high-speed playback, the playback head traces across multiple recording tracks, causing noise bars to appear on the screen.

Recently, VTRs have been released that have increased the number of heads and can provide a clear screen with no noise even during special playback.This VTR provides a noise-free screen during static and low-speed playback, but produces noise during high-speed playback. appears on the screen. Furthermore, since the tape is fed intermittently, control of the tape speed becomes complicated.

On the other hand, the playback head is mounted on a drive element made of piezoelectric ceramic plates bonded together, and an electric field corresponding to the special playback mode is applied to the drive element so that the head can trace the recording track during special playback. There are commercially available VTRs that produce a noise-free playback screen by applying a voltage and displacing the head.

However, it is difficult to attach the drive element to the rotating cylinder.
The stability of the position of the tip of the drive element has deteriorated, making it difficult to control the position of the head on the drive element.

Purpose of the Invention The present invention solves the above-mentioned problems and provides a rotary cylinder device for a VTR that enables noiseless special playback with easy head position control by mounting the head on a drive element with a stable tip position. It is about providing.

Structure of the Invention In order to achieve this object, the present invention comprises one or two annular piezoelectric ceramic plates each having an annular main surface divided into two equal parts in the diametrical direction and having electrodes attached thereto, at least in the inner diameter. A bonded drive element is constructed by pasting concentrically on one or both sides of an annular thin metal plate whose inner diameter is smaller than the inner diameter of the piezoelectric ceramic plate, and is fixed to the rotating cylinder at the metal plate portion on the inner circumference of the drive element. However, since the magnetic head is mounted near the outer periphery, the positional stability of the head is good and the position can be controlled with high precision. Therefore, the head can completely trace the recording track even during special playback.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail. Figure 1 shows an annular piezoelectric ceramic thin plate used in one embodiment of the present invention. In the figure, 12 openings are formed on the front and back surfaces of the piezoelectric ceramic plate, and the front surface has two electrodes (shaded areas) in the diametrical direction. It is divided. The back side is the adhesive surface to the thin metal plate and is a full-surface electrode. Note that the polarization direction of the piezoelectric ceramic plate is the thickness direction.

FIG. 2 is an overview of a laminated drive element using the piezoelectric ceramic plates shown in FIG. Entire mold drive element,
4. 4' and 4' are electrode lead wires for applying an electric field to the drive element 3. The zero piezoelectric ceramic plates 1 and 1' are attached to the thin metal plate 2 so that the parts without electrodes are aligned vertically. It is matched.

FIG. 3 shows the displacement direction of the drive element of FIG. 2. FIG. In the figure, reference numerals 6 and 6' are fixtures for the drive element 3. The arrow indicates the direction of displacement when an electric field is applied to the drive element 3. If a magnetic head is mounted on the tip of the drive element 3,
Move the head in the direction of the arrow.

Figure 4 shows an example of the drive element shown in Figure 2 being fixed to a rotating cylinder. It is a fixture for fixing to the rotating cylinder, and the metal thin plate part 2
It is formed to press.

8 is a rotating cylinder, 9 is an annular fixing part on the rotating cylinder, and the fixing tool 7 and this fixing part 9 together form the thin metal part 2.
Press and hold. The head 6.6' becomes displaceable in the direction of the arrow. The head 6.6' has electrode leads ma + 4 and 4. They are operated separately by applying separate electric fields to A and B.

FIG. 6 shows another example in which the drive element shown in FIG. 2 is fixed to a rotating cylinder. In the figure, reference numeral 10 denotes a fixture for fixing the drive element 3 to the rotating cylinder, and a support part 1 that supports the part of the drive element 3 to which no electrodes are attached.
0' is different from the configuration shown in FIG. 4. Reference numeral 11 denotes a rotary cylinder, which is provided with a fixing part 12 in the circumferential direction and a supporting part 12' in the diametrical direction.

In the embodiments shown in FIGS. 4 and 6, during special playback, the electric field corresponding to the deviation between the recording track and the traveling trajectory of the head causes
The trajectory of the head has been corrected to constantly trace the recording track and provide a clear screen with no noise.

Effects of the Invention As described above, the present invention can be used as a drive element for a head.
Adopting an annular bonded drive element and fixing the metal plate on the inner periphery of the drive element, the bending vibration state of the drive element is not hindered, and the positional stability of the tip of the outer periphery is maintained. It also has the characteristics of being reliable and easy to attach to the rotor/cylinder. The good tip position stability also has the effect of simplifying head position control.

[Brief explanation of drawings]

Figure 1A9 is a plan view showing the shape and electrode structure of an annular piezoelectric thin plate, Figure 2 is an overview diagram showing an example of a bonded drive element used in the present invention, Figure 3 FIG. 4 is an exploded perspective view showing the state in which the drive element of FIG. 2 is fixed to the rotating cylinder in one embodiment of the present invention; FIG. FIG. 2 is an exploded perspective view showing a state in which the drive element of FIG. 2 is fixed to a rotating cylinder in another embodiment of the present invention. 1.1'... Circular expansion pressure electromagnetic plate, 2...
- Annular metal thin plate, 3... Entire drive element, 4.
4', 4'... Electrode lead wire, 6, 6'...
・Fixing tool, 6゜6'...Magnetic head, 7...
...Fixing tool, 8...Rotating cylinder, 9...
...fixing part, 10...fixing tool, 10'...
... Support part, 11 ... Rotating cylinder, 12
...Fixed part, 12'... Support part. Figure 1 Figure 4 Figure 5

Claims (1)

[Claims] An annular piezoelectric ceramic thin plate having an electrode attached thereto and having an annular main surface divided into two equal parts in the diametrical direction is attached with a concentric circle on one or both sides of the annular thin metal plate whose inner diameter is at least smaller than the inner diameter of the piezoelectric ceramic plate. A bonded driving element is constructed by pasting the drive element into a shape, and by fixing the metal plate part of the inner periphery of the driving element in a circumferential manner, it is fixed to a rotating cylinder, and a magnetic head is attached to the opposing part of the outer periphery. 1. A rotary cylinder device comprising: a rotary cylinder mounted on a magnetic tape; an electric field is applied to the driving element to cause the driving element to be displaced in a bending vibration state, thereby enabling the magnetic head to be displaced in the width direction of a recording track on a magnetic tape;