JPH01118258A - Rotating head device - Google Patents

Abstract

PURPOSE:To restrain the vibration of a tape by its springing up to the utmost and to eliminate the bend and color slurring of a picture plane by forming the projecting part of a fixed drum by two circular arc parts and arranging the circular arc part having a larger radius at a non-winding tape side. CONSTITUTION:The projecting part 6 provided at the position where a rotary head 7 is rushed in or separated from a tape 1 is formed by the 1st circular arc part DE co-axial with a fixed drum 4 and the 2nd circular arc part EF having smaller diameter than that. The large diameter circular arc part DE is arranged so as to become at the nonwinding side of the tape 1. With this structure, the rotary head 7 is passed through a locus (m) and brought into contact with the tape 1 at a point G without causing its spring-up. The relation of the rushing and separating of the head 7 and tape 1 is not varied excepting the winding angle of the tape to the circular arc part DE being varied even if the position of a guide post 2 is varied a little and the vibration of the spring-up is restrained to the utmost and the picture plane of good quality is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a rotary head device, such as a video tape recorder, which uses a rotary head to record and reproduce signals on a magnetic tape.

Conventional technology In recent years, video tape recorders (hereinafter referred to as VTRs) have become increasingly smaller and lighter, have higher image and sound quality, and are more multifunctional. The number of rotary heads has increased significantly due to the addition of rotary audio (hereinafter referred to as FM audio) heads for higher sound quality, special playback heads for multi-functionality, and rotary erase heads for multi-functionality. There is.

Accordingly, even on VTRs of the same format,
The number of rotating heads varies depending on the model.

For this reason, when performing compatible playback between VTRs with different numbers of rotating heads, the tape vibration that occurs when the rotating head enters and leaves the tape causes local bending and color unevenness in the playback screen, which significantly degrades the playback image quality. It had deteriorated.

Problems to be Solved by the Invention A major problem associated with the difference in the number of rotating heads between models is the tape vibration that occurs when the rotating head enters and leaves the tape during compatible playback between VTRs with different numbers of rotating heads. The causes of local bending and color unevenness of the reproduced screen and deterioration of the reproduced image quality are as follows.

When a rotating head, which is attached to a magnetic tape wound around a rotating drum and protrudes a predetermined amount from the rotating drum, enters and leaves the rotating drum at high speed, the impact causes vibrations in the magnetic tape.
The vibrations of the magnetic tape that occur directly result in changes in the relative speed between the rotary head and the magnetic tape, resulting in time axis fluctuations in the recording signal and reproduction signal.

If the timing and amount of relative velocity fluctuations between the magnetic tape and the rotary head during recording and playback are the same,
There is no change in the playback signal (there is no effect on the playback image quality, but
If the number of heads during recording and playback is different, or when the rotating head enters the magnetic tape during recording and playback, i1! If the release timing is off, time axis fluctuations will occur in the reproduced signal, resulting in a curved playback screen, or the phase relationship between the color subcarrier and the reproduced video signal will be disrupted, resulting in hue fluctuations (color shift). .

In view of the above-mentioned problems, the present invention suppresses the vibration of the magnetic tape that occurs when the rotating head enters and leaves the magnetic tape, so that the playback screen does not curve even when playing compatible with VTRs with different numbers of rotating heads. and 7. To provide a rotary head device that can obtain good reproduced image quality with almost no color shift.

Means for Solving the Problems The rotary head device of the present invention is provided with at least one rotary head, and at the outer periphery of a fixed drum around which a magnetic tape is wound, a part of the rotary head that enters the tape; A rotary head device comprising a convex portion in contact with the magnetic tape near one or both of the detachment portions, the rotary head device comprising:
The outer shape of the convex portion is formed into a shape in which a first circular arc portion concentric with the fixed drum and a second circular arc portion having a radius smaller than the radius of the first circular arc portion are smoothly continuous, and the magnetic The first arcuate portion is arranged on the non-winding side of the fixed drum with respect to the contact point between the tape and the convex portion.

Effect: By the means described above, it is possible to reduce the speed of the magnetic tape in the tape thickness direction when the rotating head enters the magnetic tape or leaves the magnetic tape, and as a result,
Vibration of the magnetic tape caused by the rotating magnetic head can be prevented as much as possible.

Embodiment FIG. 1 shows a plan view of an embodiment of the rotary magnetic head device of the present invention, and FIG. 2 is a side view of the same. In Figures 1 and 2, 1 is a magnetic tape, and guide post 2
is guided around the rotary drum 3 and fixed drum 4. The tape 1 has a lead 5 formed on a fixed drum 4.
Drive in the direction of arrow A while following. 6 is fixed drum 4
The position of this protrusion 6 is near the position where the rotary head 7 fixed to the rotary drum 3 enters into and leaves the tape 1. The rotary drum 3 rotates in the direction of arrow B, and the rotary head 7 performs magnetic recording and reproduction on the tape 1.

FIG. 3 is an enlarged view of the portion indicated by C in FIG. 1, that is, the vicinity where the rotary head 7 enters the tape 1. This will be explained below using FIG. As shown in FIG. 3, the convex portion 6 integrally provided on the fixed drum 4 has a first circular arc portion DE concentric with the fixed drum, and a second circular arc portion EF having a radius smaller than the radius of DE. is a smoothly continuous shape. Therefore, the tape 1 extends from a straight line area P from exiting the guide post 2 to contacting the first arc part DE, to an arc area Q that wraps around the first arc part DE, and to an arc area that wraps around the second arc part EF. Passing through S, passing through the straight line area T,
It reaches the arc region U that wraps around the outer peripheral surface of the fixed drum 4.

Now, the fixed drum 4 and the rotating drum 3 are concentric and have the same radius, and the radius of the circular arc portion 7a at the tip of the rotating head 7 is set smaller than the radius of the second circular arc portion EF. Further, the amount of protrusion of the rotary head 7 from the outer circumferential surface of the rotary drum 3 is Hh, which is slightly smaller than the protrusion 1tHb of the first circular arc portion DE from the outer circumferential surface of the fixed drum 4.

Under the above conditions, when the rotary head 7 rotates in the direction of arrow B, the tip of the rotary head 7 passes along the trajectory indicated by m, and the rotary head 7 touches the tape 1 at a point G on the arc region S of the tape 1. enter abruptly.

By the way, since the conventional rotary head device did not have the convex portion 6, when the rotary head 7 fixed to the fixed drum 4 rotates in the direction of arrow B, as shown in FIG. It passes through the trajectory indicated by rn and enters tape 1 at one point on tape 1. One point is clearly on the linear region of tape 1.

Now, at the moment when the rotary head 7 plunges into the tape 1, the rotary head 7 flips up the tape 1 in the tape thickness direction. For example, in the case of a small diameter cylinder in a VH8 type VTR, this flip-up speed Vn is 5.8 m
/sec, the radius of the circular arc portion 7a at the tip of the rotating head is 8 mm, the radius of the outer peripheral surface of the rotating drum 3 is 20 mm, 7 mm,
The protrusion lHh of the rotating head 7 is 35. If it is czm,
Exceeds 250 nvn/see.

On the other hand, returning to FIG. 3 and considering the case where the convex portion 6 is provided, Hb is 40 μm, radius of the second circular arc portion EF is 15
mm, and other quantities are the same values as above, the tape flip-up speed Vn is 100 + nm/see, which means that the tape flip-up is significantly lower than that of the conventional rotary head device without convex portions shown in Fig. 4. The speed will be reduced.

The above description has been given in the vicinity where the rotary head enters the tape, but it goes without saying that the same applies to the vicinity where the rotary head leaves the tape.

As described above, according to this embodiment, the rotary head enters and leaves the tape extremely smoothly, so vibrations induced in the tape can be suppressed to a minimum, and as a result, the rotary head and Changes in the relative speed of the magnetic tape are extremely small, resulting in stable and good reproduced image quality.

As mentioned above, in order for the rotating head to enter the tape and exit W1 smoothly, the tape near the point where the rotating head enters and exits the tape should be shaped into an arc. , if only this purpose is achieved, then the fifth
It is also possible to have a convex shape as shown in the figure.

That is, in FIG. 5, reference numeral 6 denotes a convex portion having a radius larger than the radius of the circular arc portion at the tip of the rotary head 7 provided on the outer peripheral surface of the fixed drum 4. However, in such a configuration, when the position of the guide post 2 shifts to the right in FIG. It enters the tape 1' at a point G' on the straight line area of the tape 1', and the effect of the convex portion 6 is lost. Therefore, when adopting the configuration shown in FIG. 5, the effect of suppressing tape vibration cannot be expected unless the relative positions of the fixed drum 4 and the guide post 2 are maintained with high precision.

On the other hand, as is clear from looking at the convex portion 6 in FIG. The relationship between entering and exiting tape 1 remains unchanged. As described above, according to this embodiment, since the convex portion 6 has the arcuate portion DE that is concentric with the fixed drum 4, regardless of a slight change in the relative position between the fixed drum 4 and the guide post 2, A stable tape imaging suppression effect can be achieved.

Effects of the Invention According to the rotating magnetic head device of the present invention, it is possible to suppress as much as possible the vibrations of the magnetic tape caused by the rotating head entering and leaving the magnetic tape, and as a result, changes in the relative speed between the rotating head and the magnetic tape can be suppressed. Even during compatible playback between VTRs with different numbers of rotating heads, stable and good playback image quality can be obtained with almost no distortion or color shift occurring on the playback screen.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an embodiment of the rotary head device of the present invention;
Figure 2 is the same side view, Figure 3 is a partially enlarged view of Figure 1, and Figure 4 is the same side view.
The figure is a partially enlarged plan view of a conventional rotating magnetic head device.
The figure is a plan view for explaining the operation. 1...Tape, 2...Guide post,
4. Old... fixed drum, 6... convex part, 7...
...Rotating head. Name of agent Patent attorney Toshio Nakao 1 person 1 - Tape 3 - Rotating drum 6 - Convex Figure 1 Figure 2 Figure O 5 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] The magnetic tape is provided with at least one rotating head, and the magnetic tape is disposed on the outer periphery of a fixed drum around which the magnetic tape is wound, and in the vicinity of either or both of the entry and exit portions of the rotating head into the magnetic tape. A rotary head device comprising a convex portion in contact with the convex portion, the convex portion having an outer shape including a first circular arc portion concentric with the fixed drum, and a second circular arc portion having a smaller radius than the radius of the first circular arc portion. The first circular arc portion is formed in a smoothly continuous shape, and the first circular arc portion is arranged on the non-winding side of the fixed drum with respect to the second circular arc portion. head device.