JPH0770117B2 - Rotating magnetic head device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary head device such as a video tape recorder for recording / reproducing a signal by using a rotary head on a magnetic tape.

2. Description of the Related Art In recent years, video tape recorders (hereinafter referred to as VTRs) have become smaller and smaller, have higher image quality, higher sound quality, and have more and more functions. The number of rotary heads has increased significantly due to the addition of rotary audio (hereinafter referred to as FM audio) heads for higher performance and higher sound quality, special playback dedicated heads for higher functionality, and rotation erase heads. There is.

Accordingly, even in VTRs of the same format, the number of rotary heads varies depending on the model.

Therefore, during compatible playback between VTRs with different numbers of rotary heads, local bending and color unevenness of the playback screen occur due to the effect of tape vibration that occurs when the rotary head enters and leaves the tape, and the playback image quality is remarkably high. It had deteriorated.

One of the major problems with the difference in the number of rotary heads between models is that the VTRs with different numbers of rotary heads are compatible with each other. Causes of curling and color unevenness and deterioration of reproduced image quality are as follows. Vibration occurs on the magnetic tape due to the impact when the rotary head that is attached to the rotary drum by protruding a certain amount into and out of the magnetic tape wound around the rotary drum at high speed enters and leaves. The vibration of the magnetic tape that is generated remains as it is. The relative speed between the rotary head and the magnetic tape changes, and the recording signal and the reproduction signal change with time.

If the timing and the amount of change in the relative speed of the magnetic tape and the rotary head 8 (FIG. 5) during recording and reproduction are exactly the same, there will be no change in the reproduction signal and the reproduction image quality will not be affected at all. When the number of heads at the time of playback is different,
If the timings of the rotary head entering and leaving the magnetic tape during recording and playback are different, the playback signal will be subject to time axis fluctuations, which will cause the playback screen to bend, and the color subcarrier and playback video signal. Phase relationship is disturbed and hue changes (color shift)
Occurs.

These phenomena will be described with reference to FIG. 5. The example head drum shown in FIG. 5 is used in a VHS movie, where 1 is a head tram and (8-1) to (8-4) are recording / reproducing. The head 2, the tape on which the incident light enters, the tape 3 that emits the light, and the heads (8-1) to (8-4) rotate in the direction of arrow A. It is in the range from point 6 to point 7 that the heads (8-1) to (8-4) contact the tape and the signal is recorded. When the signal recording head comes to the (8-2) position, the head at the preceding (8-4) position separates from the tape, and the head at the (8-1) position starts contact with the tape. Next, when the signal recording head comes to the (8-3) position, the head at the preceding (8-4) position separates from the tape, and the head at the (8-1) position starts contact with the tape. . Due to the impact at this time, the relative speed between the signal recording head and the tape fluctuates, which causes the reproduced screen to be curved or causes color misregistration.

As a countermeasure against this, as shown in FIG. 6, which is a view of the head drum viewed from above and the upper rotary drum is removed,
11 is provided with a convex portion by cutting. This convex position is the position where the magnetic tape is in sliding contact, and
This is an area in which signals other than video signals such as vertical synchronizing signals that do not affect the video signals to be reproduced are recorded, or no signals are recorded.

Problems to be Solved by the Invention In FIG. 6, a signal recording head 8 rotates in the direction of arrow A. In the vicinity of the point 9 at which the head 8 contacts the tape 2, the surface of the head drum 1 connected to the convex portion 11 and the tape 2
Since there is a space between the head and the tape 2, the impact when the head 8 contacts the tape 2 cannot be completely weakened, and the tape vibrates. There was a problem that the effect still appeared on the playback screen as a curve or uneven color. Further, in order to completely absorb the shock, it is desirable to provide convex portions both near the tape entry portion and near the tape removal portion,
As shown in Fig. 3, the tape 2 is
Since the lead 10 formed on the fixed-side head drum 1 that regulates the lower end and the convex portion 4 are very close to each other, there is a problem that it is difficult to perform cutting.

In view of the above-mentioned problems, the present invention further improves the effect of preventing vibration of the magnetic tape that occurs when the rotary head enters or leaves the magnetic tape, and thus the VT having a different number of rotary heads is used.
To provide a configuration of a rotary magnetic head device capable of obtaining a good reproduction image quality without causing a bend and a color shift on a reproduction screen even when compatible reproduction is made between Rs.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides the above-mentioned device near a tape entrance portion and / or a tape exit portion of a fixed drum of a rotary magnetic head device around which a magnetic tape is wound. A rotary magnetic head device comprising a convex portion in contact with a magnetic tape, wherein a line segment passing through a contact start point between the incident tape and the rotary head and parallel to the rotation center axis of the rotary head is the incident side convex portion. It exists on the outer peripheral surface of the incident side convex portion between the contact start point and the contact end point of the incident tape, or passes through the contact end point of the output tape and the rotary head and is parallel to the rotary head rotation center axis. The convex portion is formed on the fixed drum so that a straight line segment exists on the outer peripheral surface of the emission side convex portion between the contact start point and the contact end point of the emission side convex portion and the ejecting tape.

Action The present invention has the above-described configuration, and the sliding contact pressure between the magnetic tape and the magnetic head at the tape incident portion and / or the tape detaching portion is reduced, so that vibration is generated at the tape incident portion and / or the tape detaching portion. Weakened.

Embodiment A specific embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a view of the fixed drum of this embodiment as seen from above. 1 is a fixed-side drum, 2 is an incident tape, 3 is an outgoing tape, 4 is a convex portion near the tape incident portion, 5 is a convex portion near the tape detaching portion, and an effective signal is in the range from point 6 to point 7. It is the recording / playback range, and points (6 ~
6 ') and points (7 to 7') are in the margin range of the recording signal, the tape 2 contacts the fixed drum 1 at the point 6 ', and the tape 2 makes the tape 2 at the fixed drum 1 at the point 7'.
To leave.

The convex portions 4 and 5 are the positions where the magnetic tape slides,
In addition, it is an area in which signals other than video signals such as vertical synchronizing signals that do not affect the video signals to be recorded / reproduced are recorded, or no signals are recorded.

FIG. 2 shows the shape of the convex portion 4 viewed from above. A rotary head 8 contacts the tape 2 at a point 9, and the tape contacts the outer circumference of the fixed head drum 1 at a point 6 '. The point 9 is a contact start point 12 between the tape 2 and the incident side convex portion 4 and a contact end point 13 between the tape 2 and the incident side convex portion 4.
Since it is on the outer peripheral surface of the incident-side convex portion 4 between and, the contact between the tape 2 and the rotary head 8 is always started on the outer peripheral surface of the convex portion 4. For this reason, the relative protrusion amount of the rotary head 8 with respect to the tape 2 gradually increases from the state of 0 and becomes a regular (predetermined) protrusion amount, so that the tape 2 is not suddenly impacted.

FIG. 3 is a view of the convex portion 4 of FIG. 2 viewed from the direction of arrow B, and a line segment 9'is a point 9 at which the tape 2 and the head 8 start contacting each other.
It is a line segment that runs through and runs parallel to the central axis of the head drum. The convex portion 4 has a shape in which the line segment 9'exists on the convex portion 4.

Further, FIG. 4 is a view of the fixed-side head drum in the vicinity of the convex portion 4 as seen from above, and the vicinity of the protruding portion 4 is thinned (T ₂ is formed to be much thinner than T). Therefore, the amount of protrusion H and the width W of the protrusion 4 can be accurately formed integrally with the fixed-side head drum by plastic deformation, so that the protrusion 4 on the tape incident side, which is difficult to form by cutting, can be made magnetic. Accurate formation at the position where the tape is in sliding contact and where signals other than video signals such as vertical sync signals that do not affect the video signals to be recorded / played back are recorded or where no signals are recorded. can do. In addition, since the tape 2 is always in sliding contact with the convex portion 4 near the point 9 where the head 8 contacts the tape 2, it is possible to weaken the impact due to the head 2 entering and to sufficiently warm the generated tape vibration. Although FIG. 2, FIG. 3, and FIG. 4 are explanations on the tape incident side, the same can be said on the tape detaching side.

EFFECTS OF THE INVENTION As is apparent from the above description of the embodiments, according to the present invention, the magnetic field is provided near the tape entrance portion and / or the tape exit portion of the fixed drum of the rotary magnetic head device around which the magnetic tape is wound. A rotary magnetic head device comprising a convex portion in contact with a tape, wherein a line segment that passes through a contact start point between the incident tape and the rotary head and is parallel to the rotation center axis of the rotary head is incident on the incident side convex portion. Existing on the outer peripheral surface of the incident side convex portion between the contact start point and the contact end point of the tape, or passing through the contact end point of the output tape and the rotary head and parallel to the rotation center axis of the rotary head. By forming the convex portion on the fixed drum so that the line segment exists on the outer peripheral surface of the emitting side convex portion between the contact start point and the contact end point of the emitting side convex portion and the emitting tape, the tape incidence In the department The contact start point between the incident tape and the rotary head is on the outer peripheral surface of the incident side convex section between the contact start point between the tape and the incident side convex section and the contact end point between the tape and the incident side convex section. Therefore, the contact between the tape and the rotary head always starts on the outer peripheral surface of the convex portion, and the relative protrusion amount of the rotary head with respect to the tape gradually increases from the state of 0 to the regular (predetermined) protrusion amount. Therefore, the tape will not be suddenly shocked, and the tape detachment part will not be similarly shocked, thereby eliminating the image warp and color misregistration that occur on the playback screen. be able to.

[Brief description of drawings]

FIG. 1 is a plan view showing a fixed head drum of an embodiment of the present invention, FIG. 2 is a plan view showing a convex shape of an embodiment of the present invention, and FIG. 3 is a projection of an embodiment of the present invention. FIG. 4 is a schematic view showing the positions of parts, FIG. 4 is a plan view of a main part showing a shape of a fixed head drum in the vicinity of a convex portion of an embodiment of the present invention, FIG. 5 is a plan view showing a conventional head drum, and FIG. Is the projection and tape of the conventional example,
It is a schematic diagram which shows the relationship with a head. 1 ... Fixed head drum, 2 ... Incident tape, 3 ...
... Tape to be detached, 4 ... Incident side convex portion, 5 ... Ejection side convex portion, 8 ... Rotating head.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshiteru Hosokawa 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Koji Yabuta, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (1)

[Claims] 1. A rotary magnetic head device comprising a fixed drum of a rotary magnetic head device around which a magnetic tape is wound, and a convex portion which is in contact with the magnetic tape is provided near the tape entrance portion and / or near the tape exit portion. A line segment that passes through the contact start point between the incident tape and the rotary head and is parallel to the rotary center axis of the rotary head is located between the contact start point and the contact end point between the incident side convex portion and the incident tape. A line segment existing on the outer peripheral surface of the incident side convex portion or passing through the contact end point of the emitting tape and the rotary head and parallel to the rotation center axis of the rotary head starts contact with the outgoing side convex portion and the outgoing tape. A rotary magnetic head device, characterized in that it exists on the outer peripheral surface of the emission side convex portion between a point and a contact end point.