JP2556670Y2 - Magnetic recording / reproducing device - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a recording / reproducing device mounted on a head cylinder.
The present invention relates to a rotary head type magnetic recording / reproducing apparatus which performs recording and reproduction in both forward and reverse directions by a helical scan of a pair of rotary magnetic heads.

[Conventional technology]

2. Description of the Related Art Conventionally, an 8 mm video tape recorder, which is an example of a rotary head type magnetic recording / reproducing apparatus, runs at a constant speed while being wound around a head cylinder by a pair of rotary magnetic heads for recording and reproducing mounted on the head cylinder. The magnetic tape is alternately helically scanned, and guard-bandless recording and reproduction are performed by so-called azimuth-type overwriting.

When recording and reproducing PCM audio by the multi-track method, each track of the tape formed by the helical scan is time-divided into a plurality of sections, and the time-compressed PCM of the audio signal is divided into each section. The signal is recorded and reproduced.

By the way, JP-A-60-258749 (G11B 15/087)
In a rotating head type magnetic recording / reproducing apparatus that records and reproduces PCM audio in a multi-track system such as an 8 mm video tape recorder, the running direction of the tape is either forward (forward) or reverse (reverse). It describes that recording and reproduction are performed, and recording and reproduction in both forward and reverse directions are enabled by using a pair of rotating magnetic heads for recording and reproduction.

In addition to an 8 mm video tape recorder, various rotary head type magnetic recording / reproducing devices such as a rotary head type home video tape recorder and the like are used for recording and reproducing.
By switching the tape running direction of reproduction, recording and reproducing can be performed in both forward and reverse directions using a pair of rotating magnetic heads for recording and reproducing.
Playback is possible.

On the other hand, based on the guard bandless recording described above, at the time of recording, a part of the track formed with the head width (width in the height direction) of both heads is scraped off by the next track overlap recording, and the tape is taped. The track pitch (width) of each of the tracks formed is smaller than the head width of both heads.

At this time, if the tape is traveling in the forward direction, the lower ends of both heads scan over the recorded track formed immediately before, and if the tape is traveling in the reverse direction, the upper ends of both heads are recorded. Scan over the truck.

[Problems to be solved by the invention]

By the way, based on the mounting error between the two heads, a difference (mounting step) occurs between the mounting heights of the two heads.

If the lower end positions of both heads are displaced by t due to the mounting step of both heads, the tape is run in the forward direction and recording is performed, and the track pitch of each track to be recorded is ideally free of mounting steps. The track pitch T is changed from the specified track pitch T set by the condition by the mounting step t, and tracks of track pitches T + t and T−t are alternately formed on the tape. The characteristics deteriorate.

On the other hand, based on the dimensional error, a difference occurs between the head widths of the two heads.

For this reason, even if the S / N characteristics are set within a predetermined allowable range by controlling the mounting steps to reduce the displacement of the lower end positions of the two heads and suppressing the change in the forward and backward recording and playback track pitches, the characteristics of the two heads are maintained. Since the upper end position is shifted by the difference between the mounting step and the head width, for example, the lower end positions of both heads are shifted by the above-mentioned t due to the mounting step, and the head width of the head with the higher mounting position is low. If the head width is larger than the head width of the other head by h, the track pitch T + t + h, T-t-h is applied to the tape during recording and reproduction in the reverse direction.
Are alternately formed, and the amount of change in the track pitch becomes larger than in the case of recording and reproduction in the forward direction, so that the S / N characteristic deteriorates.

That is, this type of conventional magnetic recording / reproducing apparatus using a pair of rotating magnetic heads for recording and reproducing in both forward and reverse directions is based on a head mounting error and a dimensional error. Even if there is a difference in the S / N characteristics and the mounting steps are managed to suppress the deterioration of the recording and reproduction characteristics in the forward direction, the characteristics of the recording and reproduction in the reverse direction are greatly deteriorated, and the recording and reproduction in both the forward and reverse directions are performed. Cannot be performed well.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a magnetic recording / reproducing apparatus capable of suppressing deterioration in recording and reproducing characteristics in the reverse direction due to a change in track pitch and capable of performing recording and reproduction in both forward and reverse directions.

[Means for solving the problem]

Means for achieving the above object will be described below with reference to FIG. 1 corresponding to the embodiment.

According to the present invention, a pair of rotating magnetic heads (2) and (3) for recording / reproduction mounted on a head cylinder (1) helically scans a magnetic tape whose traveling direction is switched between forward and reverse, and performs forward scanning. A magnetic recording / reproducing apparatus for performing recording / reproducing in the reverse direction and recording / reproducing in the reverse direction, wherein the head width of the other head (3) is formed smaller than the head width of the other head (2); Technical measures are taken to make the lower end position of the other head (3) higher than the lower end position of (2).

[Action]

Therefore, the heads (2) and (3) including the mounting error
The difference between the lower end position and t ₁ of, and, if the head including a dimensional error (2), the head width Wa of (3), the difference of Wb (Wa-Wb) was t _2, of defining a head width Wb by greater than Toratsukupitsuchi T, the recording in the forward direction the tape travels in the forward direction, during reproduction, the Sukiyan phase lag of head (3) based on the difference between t ₁ of the lower end position, it is formed on tape Toratsukupitsuchi of each track is changed to the _{T + t 1, T-t} 1.

Also, when recording and reproducing in the reverse direction where the tape runs in the reverse direction, the track pitch of the head (3) based on the difference t ₁ and t ₂ is reduced, and each track formed on the tape is advanced by the advance of the scan phase. The track pitch of T + (t ₁ −
t ₂ ) and T− (t ₁ −t ₂ ).

Therefore, even if there are mounting errors and dimensional errors in the heads (2) and (3), the amount of change in the track pitch during recording and reproduction in the reverse direction is less than the amount of change in recording and reproduction in the forward direction. it manages the mounting step difference t ₁ excellent in recording, by setting the range of reproduction can be carried forward, and reverse directions of the recording and playback are both performed well.

〔Example〕

Next, the present invention will be described in detail with reference to FIGS. 1 to 3 showing one embodiment thereof.

FIG. 1 shows a case where the present invention is applied to an 8 mm video tape recorder which performs recording and reproduction of PCM audio in both forward and reverse directions. In FIG. 1, (1) is a head cylinder which rotates in a predetermined direction at a specified speed, and (2) ) And (3) are a pair of rotary magnetic heads for recording / reproducing provided in the cylinder (1), which are attached to the cylinder (1) at a distance of 180 °.

By the way, the head height of the head (2) from the lower end of the cylinder (1), that is, the lower end position of the head (2) is defined as Ha, and the head width (vertical width) of the head (2) is defined as Ha.
When Wa is used, the head width Wb of the head (3) is the head width Wa.
It is formed smaller.

The heads (2) and (3) are mounted on the cylinder (1) such that the lower end position Hb of the head (3) is higher than the lower end position Ha.

Note that, in order to perform guard bandless recording and reproduction by azimuth type overwriting by the helical scan of the heads (2) and (3), the head widths Wa and Wb are set to be at least larger than the specified track pitch T. >Wb> T.

As a result, the forward memory in which the tape runs in the forward direction,
At the time of reproduction, as shown in FIG. 2, tracks (5) of a head (2) and tracks (6) of a head (3) are alternately formed on a magnetic tape (4) by recording.

At this time, when the reference Sukiyan position of head (2), the lower end position Ha including mounting error, the difference of Hb, namely on the basis of the mounting step t _1, the Toratsukupitsuchi Sukiyan phase track (5) of the head (3) only t ₁ from the phase of the provision of Toratsukupitsuchi T shifts to the right direction of FIG. 2 (delay direction).

Therefore, track is by connexion formed on overlapping recording (5), Toratsukupitsuchi becomes _{T + t 1, T-t} 1 each (6).

On the other hand, when recording and reproducing in the reverse direction in which the tape runs in the reverse direction, the track (5) 'of the head (2) and the head (2) are put on the magnetic tape (4)' by the recording as shown in FIG. Tracks (6) 'of (3) are formed alternately.

At this time, track width Wa including dimensional error, based on the difference between t ₂ of Wb, Sukiyan width of head (3) is narrowed by the difference t ₂ than Sukiyan width of head (2), and the difference of the lower end position
Based on t _1, head (3) Sukiyan phase is shifted to the right direction of FIG. 3 (leading direction), tracks (5) Toratsukupitsuchi 'of _{T-t 1 + t 2 =} T- (t 1 -t 2) together becomes, Toratsukupitsuchi the tracks (6) 'is T + t ₁ -t ₂ =
T + (t ₁ −t ₂ ).

Therefore, by setting t ₁ ≧ | t ₁ −t ₂ |, the change in the track pitch due to the mounting step t ₁ is reduced by the difference t _2, and the amount of change in the track pitch during recording and reproduction in the opposite direction. Is less than the amount of change in track pitch during recording and reproduction in the forward direction.

Was but connexion, the forward recording, by the S / N characteristic of the reproduction to manage mounting step t ₁ so that the characteristics of the predetermined allowable range, the reverse recording, S / N characteristic of the reproduction forward Recording and reproduction characteristics, and the deterioration of the recording and reproduction characteristics in the reverse direction is suppressed, so that the recording and reproduction in both directions can be performed well.

When t ₂ = 0, the track pattern of the tape at the time of recording and reproduction in both the forward and reverse directions becomes the pattern shown in FIG. 2. At this time, the recording and reproduction characteristics in both directions are the same when they are the same. You will be in a good balanced state.

Further, when t ₁ = t ₂ , the track pitch at the time of recording and reproduction in the reverse direction is only the prescribed track pitch T. At this time, the recording and reproduction in the reverse direction can be performed in the best condition.

In the above embodiment, the present invention is applied to an 8 mm video tape recorder. However, the present invention can be applied to various types of rotary head type magnetic recording / reproducing apparatuses which perform recording and reproduction in both forward and reverse directions using a pair of rotary magnetic heads. Of course.

[Effect of the invention]

Since the present invention is configured as described above,
The following effects are obtained.

By making the head width of the other head narrower than the head width of the other head and making the lower end position of the other head higher than the lower end position of the one head, the difference between the lower end positions including mounting errors, Head width difference including dimensional error
Assuming that t ₁ and t ₂ , during forward recording and reproduction, the track pitch of each track of the tape increases and decreases from the specified track pitch by t ₁ , and at the time of reverse recording and reproduction, The track pitch of the track is (t ₁ −
t ₂ ), the track pitch increases or decreases from the specified track pitch, the amount of change in the track pitch during recording and reproduction in the reverse direction decreases compared to the conventional method, and deterioration in the characteristics of recording and reproduction in the reverse direction can be suppressed. Recording and reproduction can be performed well.

[Brief description of the drawings]

1 shows an embodiment of a magnetic recording / reproducing apparatus according to the present invention. FIG. 1 is a front view of a head cylinder, and FIGS. 2 and 3 are explanatory views of track patterns in forward and reverse directions. (1) ... head cylinder, (2), (3) ... rotary magnetic head, (4), (4) '... magnetic tape.

Claims (1)

(57) [Scope of request for utility model registration] 1. A recording / reproducing device mounted on a head cylinder.
In a magnetic recording / reproducing apparatus for performing helical scanning of a magnetic tape whose traveling direction is switched between forward and reverse by a pair of rotating magnetic heads and performing recording and reproduction in a forward direction and recording and reproduction in a reverse direction, the head of one of the heads A magnetic recording / reproducing apparatus wherein the head width of the other head is smaller than the width of the head, and the lower end position of the other head is higher than the lower end position of the one head.