JPS6045924A - Video tape recorder - Google Patents

Abstract

PURPOSE:To attain specific reproducing by the small number of heads by mounting the magnetic heads on a driving element obtained by sticking a circular metallic thin plate having a small diameter to the surface of a circular piezo- electric magnetic thin plate and fixing the driving element on a rotary cylinder only by the metallic thin plate part. CONSTITUTION:The stick type piezo-electric driving element 3 consists of ring- like piezo-electric magnetic plates 1, 1' forming electrodes on its main surfaces, an adhered metallic thin plate 2 with a small diameter and electrode lead wires 4, 4', 4''. If voltage is applied between the lead wires 4, 4', 4'', the driving element 3 is displaced so as to be curved. The driving element 3 is fixed on the rotary cylinder 5 by a fixing means 7 and a fixing part 5' through a metallic thin plate 2 and magnetic heads 6, 6' are mounted on the driving element 3. Since the heads 6, 6' are stabilized, specific reproducing can be attained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a helical scan type video tape recorder (hereinafter abbreviated as VTR).

Conventional configuration and problems thereof In a helical scan type VTR, recording of video signals is synchronized with a vertical synchronization signal, and control signals and video signals are recorded on a magnetic tape.

During playback, synchronization is achieved using a control signal, and a magnetic head on the rotating cylinder traces the recording track to play back the video signal.

That is, during normal playback, a clear image without noise can be obtained by the above method. However, during special playback such as static, low-speed, and high-speed playback, noise bars appear on the screen because the playback head traces multiple tracks.

Recently, VTRs have been released that have increased the number of heads and can provide a clear, noise-free screen even during special playback (there is no other VTR that can provide a noise-free playback screen in all playback modes).

In addition, only a read-only head is mounted on a drive element made of piezoelectric ceramic plates, and after recording a signal with the recording head, the head is displaced on the drive element so that it can trace the recording track and track during special playback. By applying an electric field corresponding to
VT moving the head to obtain a noise-free playback screen
R is commercially available.

However, recently, audio signals have been recorded and played back using FM, the number of rotating heads has increased by two compared to the conventional one, and the recording track width of the video recording head has increased to 58 μm in order to record video signals under optimal conditions. It is equipped with a total of four heads, including two 19μm motes. Adding to this the reproducing head mounted on the drive element shown above, a total of eight heads are mounted on the rotary cylinder ten.
This requires a large number of rotary transformers for input and output of the head, making it difficult to realize.

One possible way to reduce the number of heads is to mount a recording/reproducing head on a drive element, but drive elements using piezoelectric ceramics do not require direct current voltage to be applied to them, as shown in Figure 1. After the voltage is removed, residual distortion remains, and the head position on the drive element is unstable due to the unreliable mounting method, so the video signal track and control signal are It was difficult to realize this because the X value indicating the positional relationship changed.

Purpose of the Invention The present invention solves the above-mentioned problems and uses a driving element and driving method with good tip position stability, making it possible to mount a recording/reproducing head on the driving element, thereby achieving culm reproduction with fewer heads. Our goal is to provide a VTR that can.

Another object of the present invention is to provide a VTR that has good positional stability and is easy to control even when equipped with a read-only head.

Structure of the Invention In order to achieve the above-mentioned object, the present invention provides a pasting method in which a piezoelectric ceramic thin plate having a circular inner circumference and a circular metal thin plate having a circumference smaller than the diameter of the piezoelectric ceramic plate are laminated concentrically. A magnetic head is mounted on a mating piezoelectric drive element, the drive element is attached to a rotary cylinder at its inner thin metal plate part, and the drive element is fixed only by the inner thin metal plate part, thereby generating the magnetic head. The positional stability of the head is improved and the head is brought to the initial position setting by applying an alternating electric field whose amplitude value attenuates over time to the drive element. This is intended to improve the positional stability of the head.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described according to the drawings. FIG. 2 is an outline drawing of a bonded piezoelectric drive element used in one embodiment of the present invention. In the figure, reference numerals 1 and 1' denote annular piezoelectric ceramic plates having electrodes attached to their main surfaces, which are polarized in the thickness direction. 2 is a thin metal plate, 3 is the entire piezoelectric drive element, and 4.
4', 4'' are electrode lead wires. Piezoelectric ceramic plates 1, 1'
are attached concentrically to the metal plate 2, and the electrode lead #i
When an electric field is applied between +4° and 4', the drive element 3 is displaced in a bent position.

FIG. 3 shows how the piezoelectric drive element of FIG. 2 is attached to the rotary cylinder. In the figure, 6 is a rotary cylinder which has an annular fixing part 6' for fixing the drive element 3. FIG. The drive element 3 is fixed to the rotating cylinder 5 by a fixing member 7 and a fixing part 5' via a metal plate part on the inner circumference. 6 and 6' are magnetic heads, which are displaced in the direction of the arrow by applying an electric field to the drive element 3. Since the drive element 3 is fixed by fixing the metal plate portion in a circumferential manner, the head 6°6
' has good positional stability and can be easily fixed.

Figure 4 shows the waveform applied to the drive element and the displacement of the head. Even if there is residual strain in the drive element 3 after applying a DC voltage, the amplitude value attenuates over time due to the application of an AC electric field. , indicating that the head has settled into the initial set position.

Effects of the Invention As described above, in the present invention, the recording/reproducing head can be mounted on the drive element by employing a means for mounting the drive element with good positional stability and a drive means that can guarantee the initial setting position of the head. , 6-head configuration is possible even when FM audio is supported, a 68 μm track normal recording mode and a 19 μm track triple recording mode, and a 6-head configuration is possible, simplifying the cylinder structure. In addition to special playback, it also has the feature of being able to record single-frame recording, high-speed recording, etc. in standard formats.

Furthermore, even when only a read-only head is mounted on the drive element, the positional stability of the head is good, so that it is possible to provide a VTR capable of special reproduction in which the head position can be easily controlled.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the characteristics when a DC electric field is applied to the drive element, Fig. 2 is an outline diagram of a piezoelectric drive element used in a VTR according to an embodiment of the present invention, and Fig. 3 is a diagram showing the drive element of Fig. 2. FIG. 4 is an exploded perspective view showing the state of attachment to a rotating cylinder, and FIG. 4 is a diagram showing the state when an alternating current electric field whose amplitude value attenuates over time is applied to a drive element with residual strain. 1.1'...Piezoelectric ceramic plate, 2...Metal plate, 3...Drive element, 4.4', 4"...
・Electrode lead wire, 6゜5'...-Rotating cylinder and fixed part, 6,6'...Magnetic, C, 7...Mountain fixing tool. Name of agent: Patent attorney Toshio Nakao and one other name
1 Figure Time Opening 2 Figure 4 U Dimension 閤

Claims (1)

[Claims] A position where the magnetic head is placed opposite to a bonded piezoelectric drive element in which a thin piezoelectric ceramic plate having a circular inner circumference and a thin circular metal plate having at least an inner circumference smaller than the diameter of the piezoelectric ceramic thin plate are laminated concentrically. The driving element is attached to the rotary cylinder at the metal plate portion of the thin metal plate on the inner periphery, and the magnetic head is moved in the width direction of the recording track of the magnetic tape by applying an electric field to the driving element. In order to enable displacement and to control the position of the magnetic head when the displacement operation is stopped, an alternating current electric field with an amplitude value such that the center of the amplitude of the head becomes the initial position setting value is applied to the drive element, and A video tape recorder characterized in that the amplitude value of an alternating current electric field is attenuated at the same time.