JPH04332948A - Magnetic recording/reproducing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording and reproducing apparatus.

0002

BACKGROUND OF THE INVENTION In recent years, devices such as VTRs (video tape recorders) have been rapidly downsized, and as a result, rotating drums have also become smaller, allowing tape to be transferred to the rotating drum in a small space. The tape must be wound, and the tape running path (hereinafter referred to as tape path) is also becoming more complex.

Next, two conventional examples will be explained based on the drawings. First, a first conventional example will be explained using FIGS. 3 and 4. FIG. 3 is a perspective view of a miniaturized tape path of a first conventional 8 mm VTR, and FIG. 4 is an enlarged view of the vicinity of the tape detachment point of the drum unit indicated by point 4 in FIG.

In FIG. 3, reference numeral 8 denotes a rotating drum unit, which has magnetic heads arranged at predetermined intervals around its outer periphery, and is composed of a rotating upper drum and a fixed lower drum. 9 is a capstan that transports the tape 3 at a predetermined speed; 10 is a pinch roller that pinches and transports the tape 3 together with the capstan 9; 11 is a supply reel; and 12 is a take-up reel.

The tape path shown in FIG.
24, especially the guide post 19
, 20, respectively, and a winding-side guide post, consisting of guide posts 21 and 22, respectively, the tape is wound around the drum unit at a predetermined angle.

Further, 16 is a tension regulator pin for detecting tape tension, and 17, 18, 23, and 24 are guide posts that form the tape path together with the above-mentioned guide posts 19 to 22, respectively.

Next, the operation of the first conventional example is shown in FIGS. 3 and 4.
Explain using. In FIG. 3, considering the tape running characteristics, during normal recording and playback, the tape 3 is pulled out from the supply reel 11 with a certain tension, supported by each guide post, wound around the drum unit 8,
Thereafter, it is conveyed by a capstan 9 and a pinch roller 10 and wound onto a take-up reel 12. At this time, the tape tension gradually increases from the supply reel 11 to the capstan 9.

When the tape 3 runs in reverse, the tape is immediately conveyed by the capstan 9 and the pinch roller 10 as soon as it is pulled out from the take-up reel 12. after that,
It is wound onto a supply reel 11 via a drum 8 and guides. At this time, since the tape is wound onto the supply reel 11 with a constant torque, the tension gradually decreases from the supply reel 11 to the capstan 9.

[0009] Therefore, in the vicinity of the tape separation point near the capstan 9 on the drum, the tension of the tape 3 varies greatly depending on the running direction. Therefore, when the tape is running in the normal recording or playback direction, it is stretched linearly with respect to the guides as shown by the broken line in Figure 4, but when it is running in the opposite direction, the tape tension decreases as shown by the solid line. To,
Due to the rigidity of the tape itself, it has the property of bulging out from the guides as it travels. This situation becomes conspicuous because the tape winding angle increases as the diameter of the rotating drum decreases as the device becomes smaller.

Next, a second conventional example will be explained using FIGS. 5 and 6. FIG. 5 is a perspective view of a second conventional example showing a state in which the tape in FIG. 4 is swollen and comes into contact with a D-cut, and FIG. 6 is a diagram showing the correlation between the tape winding angle and the contact pressure.

In FIG. 5, the same or corresponding parts as in the first conventional example are represented by the same reference numerals, and redundant explanation will be omitted. In addition, in FIG. 5, 4 is the tape release point on the exit side, 2
5 is a D-cut surface obtained by D-cutting the part where the tape bulges and makes contact (Fig. 4). Next, in FIG. 6, the horizontal axis represents the tape wrapping angle θ, and the vertical axis represents the contact pressure P. In the figure, the solid line represents the D cut of the second conventional example, the dashed line represents the first conventional example, and the dotted line represents the D cut of the second conventional example. are actual measured values for each example of this invention (described later)
It shows.

As shown in FIG. 5, if the tape in FIG. 4 bulges and makes a D cut at the contacting part, the line of intersection between this D cut surface 25 and the tape running surface is
As shown by the solid line, a large peak occurs in the contact pressure between the tape 3 and the drum 1.

[0013]

As described above, in the first conventional example, when the tape is running in reverse, the tape swells, so the wrapping angle of the drum unit 8 increases, and the point where the drum unit and the tape 3 separate from each other increases. As the tape swells, the area of contact with the drum unit increases, increasing the running load, making tape running unstable, putting unnecessary load on the drive system, and in the worst case, causing the tape to loosen. There was a problem.

In addition, in the second conventional example, when the tape swells and the contact portion is escaped by D-cut, the contact pressure between the tape and the drum is reduced at the intersection line between the D-cut surface 25 and the tape running surface. A large peak occurs. For this reason,
There has been a problem in that the edge portion of the drum tends to wear out, and as this wear progresses, the contact area with the tape increases, which, combined with the high contact pressure, results in a large running load.

The present invention was made to solve the above problems, and the radius of curvature of the lower drum from the tape release point on the tape exit side of the lower drum is made smaller than the radius of curvature of the running surface of the magnetic tape. Moreover, it is formed so that it connects smoothly at the separation point, so that a stable tape running condition is achieved regardless of the tape running direction without significantly increasing costs.In particular, a PCM recording area is arranged along with a video recording area. The purpose of the present invention is to obtain a device suitable for wrapping a tape around a VTR drum at a large angle.

[0016]

[Means for Solving the Problems] Therefore, in the present invention, in a magnetic recording and reproducing apparatus that performs recording and reproducing by winding a magnetic tape around a rotating drum unit, a lower drum that guides the magnetic tape is provided with a magnetic tape during normal recording or reproducing. The radius of curvature of the lower drum from the tape separation point in the magnetic tape running direction is smaller than the radius of curvature of the running surface of the magnetic tape, and at the tape separation point, the circumferential surface of the lower drum is aligned with the tape running surface. The purpose is to achieve the above object by using a magnetic recording/reproducing device formed to slide.

[0017]

[Function] The magnetic recording/reproducing device of the present invention is characterized in that the radius of curvature of the lower drum from the tape contact point in the running direction of the magnetic tape during normal recording or playback of the lower drum that guides the magnetic tape is the radius of curvature of the running surface of the magnetic tape. By making it smaller than the radius, the circumferential surface of the drum slides on the tape running surface at the separation point.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an enlarged view of the tape path on the tape output side of the lower drum of a magnetic recording/reproducing apparatus according to an embodiment of the present invention, and FIG. 2 is a side view of the drum unit of this embodiment. In the drawings, the same reference numerals as in the conventional example indicate the same parts or corresponding components, and some parts will be explained repeatedly.

In FIGS. 1 and 2, Y is a rotary drum unit, and X is the radius of curvature of the lower drum, and the tape detachment in the running direction of the magnetic tape 3 during normal recording or reproduction of the lower drum 1 that guides the magnetic tape 3. It is the radius of curvature of the lower drum 1 from point 4. Further, Y is the radius of curvature of the running surface of the magnetic tape 3, and the radius of curvature X of the lower drum is configured to be smaller than the radius of curvature of the running surface of the magnetic tape. Further, at the tape separation point 4, the lower drum 1
The circumferential surface of the tape 3 is formed to slide on the running surface of the tape 3.

Further, 1 is a fixed lower drum, 2 is an upper drum that is rotatable with respect to the lower drum 1 and is rotated by a motor (not shown), and 13 is a plurality of drums provided at predetermined positions on the outer peripheral surface of the upper drum. 21 is a guide post immediately after the tape ejection side during normal recording and playback, 4 is a tape separation point from the lower drum on the tape ejection side, and 5 is a relief part with a radius of curvature X that smoothly connects from the separation point 4. It is.

As mentioned above, the tape 3 slacks when running in reverse, and the tape 3 wraps around the lower drum 1 more than the designed detachment point 4, leading to deterioration in running performance. The radius of curvature X of the magnetic tape 3 is smaller than the radius of curvature Y of the running surface of the magnetic tape 3. That is, since the relief portion 5 is formed, the slack tape 3 is prevented from coming into contact with the lower drum 1, and an increase in contact pressure at the detachment point 4 is suppressed, thereby allowing the tape to run smoothly. This is also clear from the fact that the contact pressure at the breakaway point in this embodiment shown in FIG. 6 is small.

[0022]

As explained above, in the present invention, the radius of curvature of the lower drum 1 is made smaller than the radius of curvature of the running surface of the magnetic tape from the tape detachment point on the tape exit side of the lower drum.
Moreover, by forming the tape so that it slides at the separation point, a stable tape running condition can be achieved regardless of the tape running direction without significantly increasing costs, and it is especially suitable for VTRs that have a PCM recording area as well as a video recording area. The larger the angle at which the tape is wrapped around the drum, the more pronounced the effect is.

[Brief explanation of the drawing]

FIG. 1 is an enlarged view of the tape path on the tape exit side of the lower drum of a magnetic recording/reproducing device according to an embodiment of the present invention.

FIG. 2 is a side view of the drum unit of this embodiment.

FIG. 3 is a perspective view of a miniaturized tape path of a first conventional 8 mm VTR.

4 is an enlarged view of the vicinity of the tape separation point of the drum unit indicated by point 4 in FIG. 3. FIG.

FIG. 5 is a perspective view showing a state in which the tape in FIG. 4 is swollen and comes into contact with a D-cut.

FIG. 6 is a diagram showing the correlation between tape wrapping angle and contact pressure.

[Explanation of symbols]

Y Rotating drum unit 1 Lower drum 3 Magnetic tape 4 Tape separation point 5 Escape part X, Y radius of curvature

Claims (1)

[Claims] Claim 1: A magnetic recording and reproducing device that performs recording and reproducing by winding a magnetic tape around a rotating drum unit,
The radius of curvature of the lower drum from the tape detachment point in the running direction of the magnetic tape during normal recording or playback of the lower drum that guides the magnetic tape is made smaller than the radius of curvature of the running surface of the magnetic tape, and the tape detaches. A magnetic recording/reproducing device characterized in that the circumferential surface of the lower drum is formed to slide on the tape running surface.