JP2595137B2 - Rotary drum device for magnetic recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a video tape recorder (VTR).
The present invention relates to a rotary drum device used in a magnetic recording / reproducing device such as a corder, etc., and more particularly to a rotary drum device which has a wide band by rotating the rotary drum at a high speed and dividing and recording into two channels.

[0002]

2. Description of the Related Art In recent years, a magnetic recording / reproducing apparatus for recording a wideband television signal such as a Hi-Vision signal has been developed. By the way, a Hi-Vision signal or the like has an information amount about five times that of a conventional NTSC signal, and it is necessary to increase the size of the rotating drum in order to record this.

[0003] However, increasing the size of the rotating drum is not preferable for making the magnetic recording and reproducing apparatus compact. Therefore, in order to keep the rotating drum at the same size as the conventional one, the rotating speed of the rotating drum is set to two of the conventional 1800 rpm.
It has been considered that the recording is performed on a magnetic tape by doubling the frequency to 3600 rpm and distributing to a two-channel magnetic head.

FIG. 11 shows such a rotary drum device. This device has four magnetic heads 2 to 5 mounted on a rotating drum 1 which rotates in the direction of arrow E. The magnetic heads 2, 3 and 4.5 are located close to each other. 4 and 3.5 are each 1
They are arranged at intervals of 80 °. Further, the magnetic heads 2, 4 and the magnetic heads 3, 5 have the same azimuth, and the magnetic heads 2, 3 and the magnetic heads 4, 5 are set so that the directions of the inclinations of the gaps are opposite to each other. A magnetic tape 6 is wound around the rotating drum 1 so as to run in the direction of arrow F.

As shown in FIG. 12, for example, after two magnetic heads 2.3 trace the magnetic tape 6 once along each of the tracks A ₁ and B ₁ , the other two magnetic heads 4.
5 traces the magnetic tape 6 once each time along the tracks C ₁ and D _{1. In} other words, the four tracks A _{1 to} D ₁ record or reproduce an image of one field. I have. The magnetic head 2 to 5 rotary drum 1 is carried through one trace per rotation, the next track A ₁ to D ₁ will trace the track A ₂ to D _2.

In this case, in FIG. 13, the upper half 8a of the screen 8 divided by the screen dividing line 7 is assigned to the magnetic heads 2 and 3, and the lower half 8b is assigned to the magnetic heads 4 and 5. I have. Note that each hatched line 2 in FIG.
Reference numerals a to 5a denote the azimuths of the magnetic heads 2 to 5 in the screen 8 for convenience, and are irrelevant to the scanning lines and the like.

FIG. 14 schematically shows how an image is reproduced. Here, the image 9 consisting of the character A is reproduced, but the upper half 8a of the screen 8 is taken up by the magnetic heads 2.3 and the lower half 8b is taken up by the magnetic heads 4.5. The image 9a is reproduced by the magnetic heads 2 and 3, and the lower image 9b is reproduced by the magnetic heads 4 and 5.

[0008]

By the way, when performing the search reproduction while fast-forwarding or rewinding the magnetic tape 6, for example, the magnetic head 2 traces across a plurality of tracks along the arrow G in FIG. Here, the case of rewind reproduction is shown). In this case, A _3, in the tracks of the C _2, A _2, C ₁ and A ₁ magnetic head 2 to match the azimuth, the site indicated by each hatched 10a~10e
Will play.

However, as described above, the image reproduced by the magnetic head 2 is displayed on the upper half 8a of the screen of FIG. 13, and therefore, as shown in FIG. to be displayed on 8b, the image 9b which has been reproduced from the track C _2, and C ₁ is also displayed on the upper half portion 8a, there is a problem that turbulence occurs in the image. Such circumstances are the same in the other magnetic head 3 to 5, for example, a magnetic head 4 in charge of lower half 8b, in addition track for the lower half 8b such the corresponding C _2, C ₁ , but also the image of the track of the a _2, a ₁ and the like to be displayed in the upper half 8a thus reproduced. As a result, as shown in FIG. 15, the image 9a to be displayed in the upper half 8a is also displayed in the lower half 8b of the screen 8,
Conversely, the image 9b to be displayed in the lower half 8b is the upper half 8a
There was a problem that it was also displayed on the screen.

[0010]

In order to solve the above-mentioned problems, a rotary drum device of a magnetic recording / reproducing apparatus according to the present invention records one screen of a television signal on four independent tracks on a magnetic tape. In the rotating drum device of the magnetic recording / reproducing apparatus, four magnetic heads for recording / reproducing on the four tracks are provided on the rotating drum, and the azimuths of the magnetic heads are all different. It is characterized by being set (configuration of claim 1).

According to another aspect of the present invention, there is provided a rotary drum device for a magnetic recording / reproducing apparatus, wherein the four magnetic heads and the azimuth are equal to each other and the gap width is at least twice the track width on the rotary drum. The present invention is characterized in that two magnetic heads for special reproduction are provided corresponding to four magnetic heads, respectively.

In the above configuration, two of the magnetic heads correspond to the upper half of an image of one screen, and the other two correspond to one.
This is particularly effective in the case where the lower half of the screen image is taken over (configuration of claim 3).

[0013]

According to the structure of the first aspect, all the azimuths of the four magnetic heads for recording / reproducing on the four tracks are made different, so that each of the four magnetic heads has a different azimuth during fast reproduction or rewinding for special reproduction such as search reproduction. Even when the magnetic head performs reproduction across a plurality of tracks, each magnetic head reproduces only the signal of the corresponding track. Thereby, the disturbance of the reproduced image at the time of the special reproduction can be reduced.

According to the second aspect of the present invention, since the special reproduction magnetic head having the gap width twice or more the track width is provided, the reproduction signal amount at the time of the special reproduction is increased, and the image quality is improved. Become like

In the case where a magnetic head for the upper half of the image and a magnetic head for the lower half of the image are provided, the image of the upper half and the lower half are conventionally provided. However, in the present invention, since the azimuths of the individual magnetic heads are all different, the above problem can be avoided.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. As shown in FIG. 2, the rotating drum device of the magnetic recording / reproducing apparatus includes two pairs of magnetic heads 22, 23 and 24 adjacent to each other on a rotating drum 21.
· 25 are arranged. Then, while rotating the rotary drum 21 in the direction of arrow E and running the magnetic tape 26 in the direction of arrow F, one screen (one field) of the television signal is transferred to the magnetic tape 26 as shown in FIG. four tracks of the above, for example, the track a ₁ to D
_It is divided into one for recording or playback.

As shown in FIG. 3, the magnetic heads 22 and 23
Is the upper half 2 of the screen 28 divided by the screen dividing line 27
8a for recording or reproduction, and the magnetic heads 24.2
Reference numeral 5 designates recording and reproduction of the lower half 28b of the screen 28. As shown by oblique lines 22a · 23a, azimuth of the magnetic head 22 in the + theta _1, azimuth of the magnetic head 23 is set to - [theta] _1. Further, the azimuth of the magnetic head 24 is set to + θ ₂ (θ ₂ > θ ₁ ), and the azimuth of the magnetic head 25 is set to −θ ₂ .

Next, specific examples of the azimuths ± θ ₁ and ± θ ₂ of the magnetic heads 22 to 25 will be described. A television signal to be recorded is a Muse signal obtained by compressing a so-called Hi-Vision signal, and a signal for one field is divided into four tracks and recorded as described above. Here, the drum diameter of the rotating drum 21 is 62 mm,
The rotation speed of the rotating drum 21 is set to 3600 rpm. The frequency allocation when recording the above-mentioned Muse signal is set to 7 MHz to 13 MHz as shown in FIG.

Assuming that the track width of each track in FIG. 1 is 20 μm, the track pitch per field is 20 μm × 4 = 80 μm. The running speed of the magnetic tape 26 is 4.4 cm / sec. At this time, since the relative speed of each of the magnetic heads 22 to 25 with respect to the magnetic tape 26 is 11.7 m / sec, the maximum and minimum recording wavelengths λ _MAX and λ _MIN corresponding to the recording frequencies of 7 MHz and 13 MHz are respectively λ _MAX = 1.6
7 μm, and λ _MIN = 0.9 μm.

On the other hand, the azimuth loss L is expressed as follows: α = azimuth shift (angle shift), W = track width (= 20 μm), and L = 20 · log ₁₀ (X / sinX) where X = (πWtanα) / λ. Become. When the relationship between the azimuth shift and the azimuth loss L at λ _MAX and λ _MIN is calculated every 0.5 ° based on the above conditions, the result is as shown in FIG.

Here, the azimuth in various VTRs that currently employ the azimuth recording method is a so-called VHS
± 6 ° (azimuth deviation is 12 °) in system, ± 7 in β system
° (Azimuth deviation is 14 °), ± 10 ° with 8mm method
(Azimuth deviation is 20 °), ± 15 ° by UNiHi method
(Azimuth shift is 30 °). Therefore, the azimuth for normal reproduction may be set near these values.

On the other hand, assuming that the minimum azimuth deviation during special reproduction is set to 8 ° where an azimuth loss of about 20 dB can be expected from FIG.
2.23 azimuths + 10 ° and -10 ° respectively
On the other hand, the azimuths of the magnetic heads 24 and 25 may be set to + 18 ° and −18 °, respectively.

Thus, during special reproduction such as search reproduction by fast-forward or rewind, for example, the magnetic head 22 moves the tracks A ₃ , D _{2 to} A ₂ ,
When performing rewind playback diagonally across D _{1 to} A ₁ …
Since the azimuths of the magnetic head 22 and the tracks A ₃ , A ₂ and A ₁ match, the portions 30 a shown by hatching,
30b and 30c are reproduced.

As described above, each of the magnetic heads 22 to 2
When the azimuth of 5 is set to ± 10 ° and ± 18 °,
The azimuth deviation between the tracks B ₁ , B _2, ... And the magnetic head 22 is 20 °, and the tracks C ₁ , C ₂ ,.
, The azimuth deviation of each of the tracks D ₁ , D ₂ ... And the magnetic head 22 is 28 °, and the minimum azimuth deviation during special reproduction is 8 °. Also, regarding the relationship between the other magnetic heads 23 to 25 and each track, the minimum azimuth deviation at the time of special reproduction is also 8 °. Accordingly, the minimum azimuth loss at the time of special reproduction is about 20 dB. For example, as shown in FIG.
The impression that the image 31b of the lower half and the lower half 31b are mixed and displayed is reduced, and a sufficient image quality can be obtained as a reproduced image for search.

On the other hand, the azimuth deviation during normal reproduction is 20 ° between adjacent magnetic heads 22 and 23, 28 ° between magnetic heads 23 and 24, 36 ° between magnetic heads 24 and 25, and magnetic heads 25 and 22. The distance is 28 °, and FIG.
Thus, an azimuth loss of about 20 dB to 30 dB can be expected between adjacent heads. Therefore, as shown in FIG. 6, for example, even when the image 31 including the character A is reproduced, the upper half image 31a and the lower half image 31b are not mixed.
A clear reproduced image can be obtained.

FIG. 8 shows recording on the magnetic tape 26 by the magnetic heads 22 to 25.
While traveling in the direction of arrow F, the magnetic heads 22 and 23 are first moved in the direction of arrow H with the rotation of the rotary drum 21 to record on two tracks A ₁ and B ₁ . By moving the magnetic heads 24 and 25 in the direction of arrow H, recording is performed on the other two tracks C ₁ and D _1, and recording for one field is completed.

FIG. 9 shows a rotary drum device according to another embodiment of the present invention. In this embodiment, in addition to the magnetic heads 22 to 25 for normal recording and reproduction on the rotating drum 21, the magnetic head 3 for special reproduction for performing special reproduction such as search reproduction and the like.
2 to 35 are provided. Each special reproduction magnetic head 32 ~
Numeral 35 denotes +, corresponding to the magnetic heads 22 to 25, respectively.
While having an azimuth of 10 °, -10 °, + 18 ° and -18 °, the gap width is equal to the track width (20 μm).
m) (about 40 μm).

FIG. 10A shows a track group A composed of a set of four tracks having different azimuths to be recorded by the magnetic heads 22 to 25 by the tape pattern coordinate method.
_{1 to} D ₁ , A _{2 to} D ₂ . Each of the magnetic heads for special reproduction 32 to 35 has a gap width extending over two tracks of a corresponding track and an adjacent track. At the time of special reproduction, the magnetic tape 26 is reproduced at 7 times speed. That is, first, the special reproduction magnetic head 32.
33 traces in the direction of arrow I across a plurality of tracks (a range of 0 ° to 180 ° on the horizontal axis in FIG. 10A).
Track special reproduction magnetic head 32 during this time to play the part 36a~36d indicated by hatching in track A _1, A _2, A ₃ and A ₄ matching azimuth, special reproducing magnetic head 33 to match the azimuth B ₁ , B ₂ , B
Site indicated by ₃ and hatching B in ₄ 37a to 37d
To play. Note that the magnetic heads for special reproduction 32 and 3
10, the envelope of the signal reproduced by
As shown in the middle (b).

After the reproduction by the special reproduction magnetic heads 32 and 33 is completed, this time the special reproduction magnetic heads 34.3 are used.
5 traces in the direction of arrow J across a plurality of tracks (range of 360 ° to 540 ° on the horizontal axis in FIG. 10A). Along with this, the special reproduction magnetic head 34 reproduces the portions 38a, 38b, 38c, etc. indicated by hatching in the tracks C ₄ , C ₅ ... Tracks D ₄ , D ₅ ... Indicated by hatching in portions 39a, 39
b, 39c... are reproduced. Thus, the special reproduction magnetic heads 32 and 33 and the special reproduction magnetic heads 34 and 35
By tracing once each time, a search image of one field is formed. Thereafter, the special reproduction magnetic head 3
Reproduction is performed alternately by 2.33 and 34.35. In this embodiment, the magnetic heads for special reproduction 32 to
Since the gap width of 35 is about twice as large as the track width, the amount of reproduced signals at the time of special reproduction is increased, and the image quality is improved.

[0030]

As described above, the rotary drum device of the magnetic recording and reproducing apparatus according to the present invention is provided with four magnetic heads for recording and reproducing on four tracks on the rotary drum, respectively. Azimuth of magnetic head is all
Te is a configuration that is set differently (the first aspect).

Since the azimuths of the four magnetic heads are all different from each other, even when each magnetic head reproduces a track across a plurality of tracks during special reproduction such as search reproduction by fast-forward or rewind, each magnetic head can be reproduced. Reproduces only the signal of the corresponding track. Therefore, it is possible to reduce the disturbance of the reproduced image during the special reproduction.

According to another aspect of the present invention, there is provided a rotary drum device of a magnetic recording / reproducing apparatus, wherein the four magnetic heads and the azimuth are equal on the rotary drum, and the track width is on the rotary drum. In this configuration, four magnetic heads for special reproduction having a gap width of twice or more of the above are provided in correspondence with the four magnetic heads, respectively.

As described above, since the special reproduction magnetic head having a gap width twice or more the track width is provided separately from the normal reproduction magnetic head, the reproduction signal amount at the time of the special reproduction increases. Image quality is improved.

According to another aspect of the present invention, there is provided a rotary drum device for a magnetic recording / reproducing apparatus, wherein two of the magnetic heads correspond to the upper half of an image of one screen.
The other two are set so as to cover the lower half of one screen image (claim 3).

As described above, when the magnetic head for the upper half of the image and the magnetic head for the lower half are provided, conventionally, the image of the upper half and the image of the lower half are mixed and displayed. However, in the present invention, since the azimuths of the individual magnetic heads are all different, the problem that the upper half image and the lower half image are mixed does not occur.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a trace pattern of a magnetic head on a magnetic tape according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing a rotary drum device in the embodiment.

FIG. 3 is an explanatory diagram showing screen division and azimuth of each magnetic head in the embodiment.

FIG. 4 is a graph showing frequency allocation in the embodiment.

FIG. 5 is a graph showing a relationship between an azimuth shift and an azimuth loss in the example.

FIG. 6 is an explanatory diagram showing a reproduced image at the time of normal reproduction in the embodiment.

FIG. 7 is an explanatory diagram showing a reproduced image at the time of special reproduction in the embodiment.

FIG. 8 is an explanatory diagram showing a relationship between a trace pattern on a magnetic tape and a magnetic head in the embodiment.

FIG. 9 is a schematic configuration diagram showing a rotary drum device according to another embodiment of the present invention.

FIG. 10 is an explanatory view showing a magnetic tape pattern in another embodiment.

FIG. 11 is a schematic configuration diagram showing a rotary drum device in a conventional example.

FIG. 12 is an explanatory diagram showing a trace pattern of a magnetic head on a magnetic tape in a conventional example.

FIG. 13 is an explanatory diagram showing screen division and azimuth of each magnetic head in a conventional example.

FIG. 14 is an explanatory diagram showing a reproduced image during normal reproduction in a conventional example.

FIG. 15 is an explanatory diagram showing a reproduced image at the time of special reproduction in a conventional example.

[Explanation of symbols]

 21 rotating drum 22-25 magnetic head 26 magnetic tape 32-35 magnetic head for special reproduction

Claims (3)

(57) [Claims] 1. A rotary drum device of a magnetic recording / reproducing apparatus for recording one screen of a television signal on four independent tracks on a magnetic tape, and recording / reproducing the four tracks on a rotary drum. A rotating drum device for a magnetic recording and reproducing apparatus, wherein four magnetic heads for performing the above-mentioned operations are provided, and the azimuths of the respective magnetic heads are all set to be different. 2. The four magnetic heads and the azimuth on the rotating drum are equal to each other and have a track width of two.
2. The rotary drum device for a magnetic recording / reproducing apparatus according to claim 1, wherein four magnetic heads for special reproduction having a gap width twice or more are provided corresponding to the four magnetic heads, respectively. 3. The magnetic head according to claim 1, wherein two of the magnetic heads are in the upper half of one screen image, and the other two are in the lower half of the one screen image. Rotary drum device of magnetic recording and reproducing device.