JPS626577Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a rotating head type magnetic recording/reproducing device (VTR), and in particular, to a rotating magnetic head so that the rotating magnetic head accurately scans over a recording track during reproduction. The piezoelectric ceramic deflection plate is provided on a piezoelectric ceramic deflection plate, and by controlling and driving the piezoelectric ceramic deflection plate, a good reproduction signal can be obtained in a VTR that controls tracking of a rotating magnetic head.

The present invention relates to high-density magnetic recording and reproducing apparatus, particularly narrow track width video tape recorders.

In recent years, the recording density of home-use VTRs has improved significantly, but as the recording track width has reached approximately 20 μm, it has become difficult to accurately trace the recording track during playback. Systems have been devised to actively control the reproducing magnetic head to minimize the degradation. In other words, a magnetic head is placed on a deflection plate made of laminated piezoelectric ceramics, and an alternating current voltage is applied to the piezoelectric ceramic deflection plate to generate vibrations due to the bimorph effect, thereby automatically scanning the recording track while searching for it. It is.

However, in a structure in which a magnetic head is provided on a piezoelectric ceramic deflection plate, it is difficult to determine the position of the magnetic head during recording due to factors such as aging of the piezoelectric ceramic, especially when there are multiple recording magnetic heads. This causes problems such as overwriting.

For this purpose, an attempt was made to separate the recording magnetic head and the reproducing magnetic head, fixing the recording magnetic head to the rotating drum by normal means, and attaching only the reproducing magnetic head to the rotating drum via a deflection plate. However, for reasons explained below, good playback quality could not be obtained. The present invention achieves the original objective in this case and provides good reproduced image quality.

Examples of the present invention will be described in detail below.

Figure 1 shows the configuration of the rotating head of a VTR.
FIG. 2 shows a cross section taken along line A-B-C.

Reference numerals 1 and 1' denote recording magnetic heads, which are fixed to bases 2 and 2' made of metal or ceramic, etc.
It is set at a three-dimensionally defined position with respect to the rotating shaft 8, and is attached to the rotating plate 7 with screws 3, 3'. Next, reference numerals 4 and 4' denote magnetic heads for reproduction, which are fixed to deflection plates 5 and 5' made of two laminated piezoelectric ceramics, and screws 6 and 6 to the rotary plate 7.
6'. These magnetic heads and deflection plates are connected to a recording/reproducing amplification circuit and a deflection drive circuit by a well-known method such as a rotary transformer or a slip ring. The above configuration is the same as the conventional configuration.

In the conventional apparatus, during recording, a recording current is passed through the recording heads 1, 1' to magnetize the magnetic tape, but the reproduction heads 4, 4' are inactive, and the deflection plates 5, 5' are not driven either. do not have. During reproduction, as described above, a predetermined alternating current voltage is applied to the deflection plates 5, 5', and the deflection plates 5, 5' are vibrated to search for and scan the recording track.

By the way, since the recording heads 1, 1' are fixedly fixed to the rotary plate 7, they are always in constant contact with the magnetic tape 10 as shown in FIG. gradually wears out depending on the state of contact, and generally reaches a so-called broken-in state after about one hour of contact. At this time, it is known that if the mounting state of the magnetic heads 1, 1' is changed to eliminate the familiar state, the output at high frequencies will decrease, which is generally referred to as the running effect.

On the other hand, in recent years, the recording time of video tape recorders has tended to become longer and longer, and the track width of the magnetic head has become smaller. If it is not fixed, it will become accustomed to its fixed state as described above. When performing a reproducing operation thereafter, the reproducing heads 4, 4' are
Since it is deflected as shown in the figure, the contact with the magnetic tape during playback is inappropriate due to the bending during recording, making it impossible to obtain a good playback output.

In this way, when using a method in which the magnetic head is deflected, fixing the magnetic head in a specific state will cause "familiarity" with that state, and it will not be possible to suitably adapt to other states. become unable to do so.

Therefore, in the present invention, when the reproducing magnetic heads 4, 4 rotate and come into contact with the magnetic tape, the deflection plate is always driven so that the magnetic heads and the magnetic tape are brought into contact with each other while accompanied by a deflection operation. . That is, even during recording, a periodic alternating current voltage is applied to the reproducing magnetic heads 4, 4' within the movement range during reproducing, and the magnetic heads 4, 4' are deflected and moved periodically.

FIG. 4 shows the maximum deflection states 4a and 4b of the magnetic head 4 on the deflection plate 5, and the worn magnetic head can be seen by running the magnetic tape for about 100 hours while applying an alternating current deflection voltage. Observing the cross-sectional shape of the magnetic head core, the sliding surface of the magnetic tape at the center of the magnetic head core has an almost circular arc, and its radius of curvature is smaller than the radius of curvature predicted from the deflection operation. The phenomenon of "familiarity" also occurs in this case. In this way, when the playback magnetic head is used while being deflected even in the recording state, a conformation is formed in the deflection state, and the contact between the magnetic head and the tape during playback is stable, and a good playback output is always obtained. Obtained.

FIG. 5 shows experimental results for confirming the effects of the present invention. This shows the maximum output when playing a recording tape while deflecting the playback head.
The deflection of the playback head is stopped, based on the state of A with the playback head that is familiar with the magnetic tape.
After rotating the playback head in the same fixed state as the recording head and running the magnetic tape continuously for 10 hours, the output when played back by the playback head was B, which was a 5 dB drop in output. From there,
By continuing the deflection operation and performing continuous regeneration, the output gradually recovered, reaching state C in about 1 hour and state D in about 1.5 hours.

As described above, the disadvantages of not implementing the present invention are great, and from this, the effects of the present invention will be understood.

[Brief explanation of the drawing]

Figure 1 is a plan view showing one embodiment of the present invention, Figure 2 is a plan view showing one embodiment of the present invention;
The figure is a cross-sectional view taken along the line A-B-C in Figure 1.
4 and 4 are side views of essential parts for explaining the present invention, and FIG. 5 is a diagram showing the relationship between usage time and relative output of the present invention. 1, 1'... Magnetic head for recording, 4, 4'... Magnetic head for reproduction, 5, 5'... Deflection plate, 7... Rotating plate.

Claims (1)

[Scope of utility model registration request] A recording magnetic head is fixedly placed on a rotating body,
A reproducing magnetic head is provided on the rotating body via a deflection plate that is deflected by application of a control voltage, and a predetermined alternating current voltage is applied to the deflection plate while forming a recording track by the recording magnetic head during recording. means for vibrating the deflecting plate, applying a predetermined alternating current voltage to the deflecting plate during reproduction, vibrating the deflecting plate, and scanning the magnetic head for reproduction along the recording track while searching for the recording track. A rotating head type magnetic recording/reproducing device having a rotary head type magnetic recording/reproducing device.