JPS5984330A - Rotary head drum - Google Patents

Abstract

PURPOSE:To prevent a tape from wearing, by putting a video head into a rotary head cylinder when a tape is rewound or quickly traversed so that the tape does not contact with the video head. CONSTITUTION:When the rewind switch 48 or quick traverse switch 49 of tape is turned on, a voltage is applied across the electrodes 43-45 of two pieces of piezo-electric elements 41 and 42 from a voltage generator 51 through a brush 50. Therefore, one side of the piezo-electric elements 41 and 42 is extended and the other side is contracted and the bimorph piezo-electric element 41 and 42 are bent along the arrow and a video head 46 is separated from a magnetic tape 47. Since the rewinding and quick traversing of the magnetic tape 47 are performed under a condition where the tape 47 does not contact with the video head 46, the magnetic tape 47 is prevented from wearing.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotating head assembly for a video tape recorder (hereinafter abbreviated as VTR). The power of face! (The purpose is to prevent unnecessary wear.)

Conventionally, Baum VTRs such as the VH3 system and the Beta system have been put into practical use and are widely used.

FIG. 1 is a diagram schematically showing a tape running path of a beta system home VTR. In the figure, 1 is an upper cylinder, 2 is a lower cylinder, and 3 is a rotating head disk. A video head 4 is fixed to this head disk and rotates integrally with it. 5
The magnetic tapes 13 and 14 are a supply reel and a take-up reel, respectively. Also, 6 is a voice control head,
8 is a full width erasing head, 9 is a capstan, 10 is a pinch roller, 11 is a tension stabilizer, and 12 is a loading ring. The main feature of the tape running path of this Beta-type home VTFt is that it has a structure that does not put stress on the tape, so the tape running is stable, and it is possible to unwind or fast forward the tape while it is loaded in the rotating head cylinder. You can get points. Of course, the video head needs to be in contact with the tape magnetic surface 7 only during recording and playback (including special playback such as slow-motion and fast-forward playback); There is no need to do this when rewinding or fast forwarding. On the contrary, keeping the video head in contact with the tape magnetic surface during rewinding or fast forwarding will unnecessarily accelerate wear of the video head and the tape magnetic surface. However, if the tape is first unloaded before rewinding or fast forwarding, there are problems in that the speed of the mode change is insufficient and the motor power is consumed unnecessarily.

In addition, tapes have recently become thinner due to the demand for high-density, long-duration recording, and the time required for rewinding and fast-forwarding has become relatively long. Therefore, unnecessary wear and tear on the video head and tape during periods other than recording and playback is a major hindrance to extending the life of the home VTR.

The present invention eliminates these conventional drawbacks and
This is intended to prevent unnecessary wear of the tape and contribute to extending the life of Bauhm VTRs.

Concrete ic &:l, rewind or fast forward the tape,
When sipping, store the video head in the rotating henodon cylinder (in other words, set the video head protruding claw to 0 or less).
This prevents wear by keeping the tape out of contact with the magnetic surface.

Hereinafter, the present invention will be explained in detail according to Examples.

Figure 2 is a diagram showing an embodiment of the GJ* invention (wiring is omitted), 15 is an upper cylinder, 16 is a lower cylinder, 17 is a diagram showing an embodiment of the invention.
(J co-rotating head disk. 18 is a piezoelectric element, 19
is integrated with the piezoelectric element 18 by a video head. 20, 21 G; attached to both sides of the J-pressure ME element? lj pole, and by applying the full voltage to this ↑l pole, the piezoelectric element 18 expands and contracts in its length direction.
can do. Generally, piezoelectric elements are polarized in the same direction as their polarization direction? 1) It has the property of contracting when pressure is applied and expanding when pressure is applied in the opposite direction. Also, its displacement (
expansion/contraction) is proportional to the applied voltage.

Now, the video head 19 attached to this piezoelectric element
However, when no voltage is applied (that is, the piezoelectric element has its natural length), the amount of protrusion from the cylinder surface is adjusted to a standard value, and the piezoelectric element is attached to the rotating head disk. Therefore, during recording and playback, the operation is no different from that of the conventional system. Next, when rewinding or fast forwarding the tape, when the rewind switch or the fast forward switch is turned on, the electrodes 20 and 21 attached to the piezoelectric element are connected to the circuit system (not shown in the figure) via the brush 22. Voltage is applied from 1). Furthermore, the direction (polarity) of this voltage is the same as the polarization direction of the piezoelectric element (i.e., the direction in which the piezoelectric element contracts), and its magnitude is equal to the amount of protrusion of the video head from the cylinder surface.
It is set large enough to: In this way, during rewinding and fast forwarding, the video head is out of contact with the magnetic surface of the tape, thereby preventing unnecessary wear. Next, when the rewind/fast forward mode is canceled or another mode switch is turned on, the applied voltage becomes zero. In this case, the piezoelectric element returns to its natural length, and the video head again contacts the tape magnetic surface with its original protrusion amount, allowing normal recording and playback. FIG. 6 shows a block diagram of a voltage supply path for realizing the present invention. 32 is a rewind switch, 36 is a fast forward switch, 34 is a brush, and 35 is an evening pressure generator.

Further, 36 is a piezoelectric element, 37 j 38 is an electrode, 39 is a video head, and 40 is a magnetic tape.

FIG. 4 is a block diagram showing another embodiment of the present invention.

In this embodiment, two piezoelectric elements 41. with different polarization directions are used.
42 is formed into a bimorph structure by three electrodes 43, 44° 45 and attached to the rotating head disk 52. During normal recording and playback (i.e., when no voltage is applied to the electrodes), the video head 46 has a specified protrusion m.
The magnetic tape 47 is adjusted so as to come into contact with the magnetic tape 47. Next, the rewind switch 48 and fast forward switch 49 are turned to
When N is applied, a brush 50 is applied to the electrode by a voltage generator 51.
A voltage is applied through. At this time, piezoelectric element 41.4
Since the polarization directions of the two are opposite (one expands and the other contracts), the bimoha 7-shaped piezoelectric element to which the video head is attached bends along the arrow in the figure, resulting in a state as shown by the dotted line, and the video head is connected to the magnetic tape. There will be no contact. In this way, unnecessary wear and tear on the video head and magnetic tape during rewinding and fast forwarding can be avoided.

Although the explanation so far has been made by taking the Beta method tape running route as an example, the present invention is not limited to this method, but can be applied to all methods in which fast forwarding and rewinding are performed while the tape is loaded in the printer.

In addition, although we have discussed a method using a brush as a method for applying voltage to the electrodes attached to the piezoelectric element, it is not limited to brushes; for example, an electromagnetic coupling method using a rotary transformer or other magnetic coupling methods may also be used. There is no difference in the effects of the present invention.

As described above, according to the present invention, wear of the video head and tape can be reduced by adding only a few parts to the conventional rotary head assembly, and its practical effects are significant. be.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the tape running path of a Beta system home VTR. FIG. 2 is a sectional view of a rotary head assembly showing one embodiment of the present invention. FIG. 3 is a block diagram of a voltage supply path to a piezoelectric element. 23...Rotating shaft 25...Ball bearing 25...
・PG coil 26 for rotational phase detection...PG magnet 27, 28...Rotary transformer 29...Preload spring 30...Stator 31 of cylinder motor...Rotor magnet Figure 4 shows the structure of the present invention. FIG. 3 is a block diagram showing another embodiment of the .

Claims (2)

[Claims] (1) A magnetic tape is wound diagonally around the outer periphery of a drum containing a rotating magnetic head, forming a magnetic recording pattern having a predetermined inclination angle with respect to the longitudinal direction of the magnetic tape, and rotating to record and reproduce signals. In the head drum, the magnetic head is installed in a rotating head drum together with a piezoelectric element so that it can be displaced in the radial direction of the drum, and can be brought into contact with or out of contact with the magnetic surface of the magnetic tape as desired. A rotary head drum characterized in that it has a structure that obtains. (2) The magnetic head is maintained in a non-contact state with the magnetic tape during tape fast forwarding and rewinding periods when no signals are recorded or reproduced. Rotating head drum.