JPH08147612A - Magnetic recording and reproducing apparatus - Google Patents

Abstract

PURPOSE: To obtain a magnetic recording and reproducing apparatus by which a recording part on a magnetic tape can be expanded to a maximum extent and by which a preceding reproducing track can be traced perfectly. CONSTITUTION: A magnetic recording and reproducing apparatus is provided with a head drum device which comprises a drum on which a magnetic tape 1 is wound helically and which comprises a magnetic head 3 used to detect information in the magnetic tape 1. The winding start position of the drum 14 for the magnetic tape 1 is set in such a way that the magnetic head 3 comes in from the side edge of the magnetic tape 1. Then, a contact prevention means 2 is fixed to a lower drum 15.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art In recent years, a magnetic recording / reproducing apparatus having a plurality of magnetic heads has been widely used for VTRs and the like.
Head drum devices are being rotated at higher speeds, shorter wavelength recording, narrower tracks, thinner magnetic tapes, and compression techniques are being introduced as signal processing.

Under such circumstances, as one of the mechanical problems, in addition to the delay time required for the shuffling of the conventional uncompressed digital VTR, the compressed digital VTR requires an extra compression / expansion time. The reason is that the number of tracks between the reproducing head and the recording head during pre-read editing increased considerably. The conventional magnetic recording / reproducing apparatus of this type has the following structure. That is, FIG. 6 is a schematic perspective view showing the positional relationship between the helical track on the magnetic tape 1 and the head drum device when the magnetic tape 1 is helically wound around the head drum device of the magnetic recording / reproducing apparatus showing the first conventional example. It is a figure. In FIG. 6, 3 is a magnetic head for magnetic recording attached to the rotating upper drum 14, 4 is a magnetic head window formed in the upper drum 14, 15 is a lower drum, 19 is a motor for rotating the upper drum 14, Reference numeral 8 is a contact start line which is a position where the magnetic tape 1 starts contacting the upper drum 14, that is, a position where winding starts.

In the first conventional example, the magnetic head 3 does not enter the magnetic tape 1 from the side edge of the magnetic tape 1 so that the contact between the magnetic head 3 and the magnetic tape 1 starts smoothly. The magnetic head 3 is configured to start contact with the inside of the side edge of the tape 1, that is, within the tape surface near the center, and the contact start line 8 is set at a position where the magnetic head 3 and the magnetic head window 4 cross. . For this reason, the winding of the magnetic tape 1 around the upper drum 14 is usually limited so as to be within the tape surface of the magnetic tape 1.

In order to clarify these relationships, FIG. 7 shows an outline of the relationship between the pattern of the magnetic tape 1 and the magnetic head window 4 or the magnetic head 3. In FIG. 7, 5 is a track at the recording position, 6 is a track when the track is taken up to the winding start line 8, and 7 is a track at the preceding reproduction position. Reference numeral 12 is a contact end line where the magnetic tape 1 separates from the upper drum 14.

Since the magnetic head 3 and the magnetic head window 4 on the magnetic tape 1 start contact with each other at the contact start line 8, the magnetic head 3 and the magnetic head window 4 start to hit from within the plane of the magnetic tape 1. However, track 7 required for pre-play
Is located on the lower side of the magnetic tape 1 with respect to the contact start line 8 and the magnetic head 3 can reproduce the entire track length up to the track 6. For this reason, even if the magnetic head 3'is set to the position shown in the figure, the tip portion of the track 7 cannot be reproduced because it does not contact. That is, a missing portion of the signal is generated.

On the other hand, FIG. 8 shows a second conventional example in which the recording start point at the entrance is shifted in order to perform read-after-write. That is, the contact start line 8 that is the start of mechanical winding is the same as that of the first conventional example, and the track length of the recording track 9 is shortened by setting the shift amount in the recording track direction as ΔL. Reference numeral 10 is a track at the preceding reproduction position. Let the track angle be θ. At this time, assuming that the track pitch is p and the drum diameter is D, the winding angle increase Δω is Δω = {ΔL / (πD / 2)} × 18
It is 0 °. Number of track pitches included in this ΔN
Becomes ΔN = ΔLtan θ / p, and the number of ΔN approaches the direction in which read-after-write is possible. In practice, the overlap amount that the VTR device originally has plus this allowance may be set to a length that allows read-after-write.

[0008]

In the first conventional example, since the winding of the magnetic tape 1 around the upper drum 14 is limited at the drum entrance as described above, the position of the pre-reproduction is limited, and therefore the compression is performed. The digital VTR of the system has a problem that the read-after-write function for one frame to several frames cannot be performed.

Further, in the second conventional example, since the track length of the recording track 9 is shortened, the shortest recording wavelength is reduced by a few percent, or there is a wasteful area on the magnetic tape in which there is no recording by ΔL × sin θ in the width direction. There is a problem in that it occurs on the magnetic tape 1 and the relative recording density of the magnetic tape 1 decreases. Therefore, the present invention solves the problems of these conventional examples, and provides a magnetic recording / reproducing apparatus capable of maximally enlarging the recording portion of the magnetic tape and completely tracing the preceding reproduction track. The purpose is to do.

[0010]

A magnetic recording / reproducing apparatus according to a first aspect of the present invention comprises a head drum device having a drum for helically winding a magnetic tape and a magnetic head for detecting information on the magnetic tape, The winding start position of the magnetic tape around the drum is set so that the magnetic head enters from the side edge of the magnetic tape.

A magnetic recording / reproducing apparatus according to a second aspect is the first aspect.
In the above, there is provided a means for preventing contact of the side edge of the magnetic tape that lifts the side edge of the magnetic tape from the drum so that the tape surface side of the side edge of the magnetic tape contacts the magnetic head.

[0012]

According to the magnetic recording / reproducing apparatus of the present invention, the winding start position of the magnetic tape around the drum is set so that the magnetic head enters from the side edge of the magnetic tape. Since the recorded portion of the magnetic tape can be expanded to the maximum and the pre-reproduced track can be completely traced even at the pre-reproduced position, the read-after-write position of the magnetic recording / reproducing apparatus can be improved. The recorded track can be completely reproduced, and read-after-write becomes possible even in the digital VTR of the compression system which has been impossible with the efficient use of the magnetic tape, so that the practical effect thereof is very large.

According to a second aspect of the magnetic recording / reproducing apparatus of the present invention, in the first aspect, the magnetic tape is floated up from the side edge of the magnetic tape with respect to the drum so that the tape surface side of the side edge of the magnetic tape contacts the magnetic head. Since the tape side edge contact preventing means is provided, the magnetic head does not come into contact with the side edge of the magnetic tape and comes into contact with the tape surface side of the side edge of the magnetic tape in addition to the function of claim 1. The contact start of is smooth.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention is shown in FIGS. That is, FIG. 1 is a schematic perspective view showing the first embodiment of the present invention. In FIG. 1, reference numeral 2 is a contact prevention means for preventing contact between the magnetic head 3 and the side ends of the magnetic tape 1.
Reference numeral 3 is a contact start line of the magnetic tape 1. In addition, the same parts as those in FIGS. 6 to 8 are designated by the same reference numerals and the description thereof is omitted.

The magnetic tape 1 sets the winding start position around the upper drum 14 of the magnetic tape 1 so that the magnetic head 3 enters from the side edge of the magnetic tape 1, and the magnetic head 3 moves the side edge of the magnetic tape 1. Is wound around the drum from the contact start line 13 of the magnetic tape 1 which comes into contact with the drum. In this case, contact preventing means 2 for preventing the magnetic head 3 from contacting the side end of the magnetic tape 1 is provided in the vicinity of the position where the magnetic tape 1 contacts the upper drum 14, and the taper portion 18 at the tip thereof is provided. It is embedded between the magnetic tape 1 and the upper drum 14.

FIG. 2 shows a partially enlarged view thereof. That is,
The contact prevention unit 2 is fixed to the lower drum 15 by a fixing tool such as a fastening member 16 such as a screw. In the contact prevention means 2, a portion that goes under the side edge of the magnetic tape 1 is a tapered portion 18, and a portion facing the outer peripheral surface of the upper drum 14 is slightly floated to prevent contact with the upper drum 14.
Further, in order to avoid contact with the magnetic head 3 protruding from the outer peripheral surface of the upper drum 14, a relief 17 is provided in the tapered portion 18. The side edge of the magnetic tape 1 has the tapered portion 18
The magnetic tape 3 is lifted up to several tens of μm at the maximum, and the side end of the magnetic tape 1 does not come into contact with the magnetic head 3 lower than that. For this reason, since the magnetic head 3 starts contact from the side of the tape surface of the side edge of the magnetic tape 1, the start of contact of the magnetic head 3 with the magnetic tape 1 is smooth, and the magnetic head 3 can be smoothly contacted. .

FIG. 3 is a schematic tape pattern diagram showing this state from the pattern of the magnetic tape 3. Reference numeral 21 denotes a raised portion on the side edge of the magnetic tape 1 due to the taper portion 18 of the contact prevention means 2. Further, since the contact start line 13 of the magnetic tape 1 is set at a position farther from the magnetic head 3 than the conventional contact start line 8, there is winding up to the position including the read-after-write recording track 7. The recording track 7 can be reproduced over the entire track length. The magnetic head 3 starts contact from the side edge of the magnetic tape 1 so that the magnetic tape 1 is a guide means for guiding the magnetic tape 1 of the head drum device in order to wind the magnetic tape 1 over the head drum device.
This can be easily achieved by changing the position of the post (not shown) in the tangential direction into which the beam enters.

According to this embodiment, since the contact start line 13 to the upper drum 14 of the magnetic tape 1 is set so that the magnetic head 3 enters from the side edge of the magnetic tape 1, the winding angle of the magnetic tape 1 is increased. Since the recording portion of the magnetic tape 1 can be maximized and the preceding reproduction track can be completely traced even at the preceding reproduction position, the read-after-write of the magnetic recording / reproducing apparatus. The recorded track at the position can be completely reproduced, and the read-after-write becomes possible even in the digital VTR of the compression system which has been impossible with the efficient use of the magnetic tape, so that the practical effect is very large.

Further, there is provided an abutting prevention means 2 for the side end of the magnetic tape 1 for lifting the side edge of the magnetic tape 1 above the upper drum 14 so that the side of the magnetic tape 1 on the side of the tape contacts the magnetic head 3. Therefore, the magnetic head 3 does not come into contact with the side edge of the magnetic tape 1 and comes into contact with the tape surface side of the side edge of the magnetic tape 1, so that the contact start of the magnetic head 3 becomes smooth.

A second embodiment of the present invention is shown in FIGS. 4 and 5.
Shown in That is, in this magnetic recording / reproducing apparatus, the magnetic tape 1 is wound up to the contact start line 13 around the head drum device as in the first embodiment. Also magnetic head 3
Is projected from the upper drum 14 by several tens of μm, but the tip of the magnetic head 3 forms an arc, so that the contact with the side edge of the magnetic tape 1 is started smoothly. The prevention means 2 is omitted.

FIG. 5 shows the upper drum 14 including the magnetic head 3.
The partially expanded view of the cross section of the rotation surface of FIG. In FIG. 5, the magnetic head 3 hits the side edge of the magnetic tape 1 to start contact, but the contact is smoothly started by the arc of the tip of the magnetic head 3, and the edge angle 4 of the magnetic head window 4 is 4 as well.
Since a has a curved surface R, the edge 4a of the magnetic head window 4 smoothly starts contact with the magnetic tape 1. In this way, the arcuate surface at the tip of the magnetic head 3 and the edge angle 4a forming the curved surface R of the magnetic head window portion 4 come into contact with and guide the side edge of the magnetic tape 1. Therefore, entering the side edge of the magnetic tape 1 through the magnetic head window portion 4 is equivalent to entering the magnetic head 3 into the side edge of the magnetic tape 1. In addition, this embodiment has the same effects as the first embodiment.

Although the upper drum 14 is rotated in each of the embodiments, the present invention can be applied to a case where the drum is fixed and only the magnetic head is rotated.

[0023]

According to the magnetic recording / reproducing apparatus of the first aspect,
Since the winding start position of the magnetic tape around the drum is set so that the magnetic head enters from the side edge of the magnetic tape, the winding angle of the magnetic tape can be dramatically improved, and the recording area of the magnetic tape can be maximized. In addition to being able to fully expand the recording track at the read / write position of the magnetic recording / reproducing apparatus, it is possible to completely trace the read / write track at the read / write position. Since a read-after-write is possible even in a compression type digital VTR, which is impossible by using a magnetic tape, its practical effect is very large.

According to a second aspect of the magnetic recording / reproducing apparatus of the present invention, in the first aspect, the magnetic tape is floated up from the side edge of the magnetic tape so that the tape surface side of the side edge of the magnetic tape contacts the magnetic head. In addition to the effect of claim 1, the magnetic head does not come into contact with the side edge of the magnetic tape and has contact with the tape surface side of the side edge of the magnetic tape. The contact start of is smooth.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing a first embodiment of the present invention.

FIG. 2 is a partially enlarged schematic perspective view thereof.

FIG. 3 is an explanatory diagram showing a positional relationship between a magnetic recording pattern and a magnetic head.

FIG. 4 is a partial schematic perspective view showing a second embodiment.

FIG. 5 is a partially enlarged schematic plan view thereof.

FIG. 6 is a schematic perspective view of a first conventional head drum device.

FIG. 7 is an explanatory diagram showing the positional relationship between the magnetic tape pattern and the magnetic head.

FIG. 8 is an explanatory diagram showing a positional relationship between a magnetic tape pattern and a magnetic head of a second conventional example.

[Explanation of symbols]

 1 Magnetic Tape 2 Contact Prevention Means 3 Magnetic Head 4 Magnetic Head Window 14 Upper Drum

Claims (2)

[Claims] 1. A head drum device having a drum for helically winding a magnetic tape and having a magnetic head for detecting information on the magnetic tape, wherein the magnetic head enters from a side edge of the magnetic tape. A magnetic recording / reproducing apparatus, wherein a winding start position of the magnetic tape around the drum is set. 2. An abutting prevention means for a magnetic tape side end that lifts the side edge of the magnetic tape with respect to the drum so that the tape surface side of the side edge of the magnetic tape contacts the magnetic head. Item 1. The magnetic recording / reproducing apparatus according to item 1.