JPH06259932A - Helical scan type magnetic recording device - Google Patents

Abstract

(57) [Summary] [Purpose] To enable insert recording that does not cause unreproducible tracks during insert recording while satisfying compatibility even in a system with a narrow track width. In a helical scan type magnetic recording apparatus for recording a signal on a magnetic tape by using a rotary head, a rotary head having a head width wider than a track pitch is used.
Means for generating a mute signal for performing recording mute at the end of insert during insert recording, means 31 for generating a track pitch change signal that rises earlier by a few tracks immediately before the end of insert, Based on the mute signal and the track pitch change signal, several tracks immediately before the end of insertion,
Means for reducing the rotational speed of the capstan (32,
25) is provided and the period of several tracks before the end of the insert,
The capstan speed was reduced to make the track pitch narrower than the regular width. As a result, it is possible to prevent the width of the first recorded track portion that appears after the end of the insert recording from becoming extremely narrow.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a helical scan type magnetic recording apparatus suitable for insert recording.

[0002]

2. Description of the Related Art As one of the video editing modes, there is an insert mode in which a part of the already recorded tape is replaced with another image for recording.

FIG. 4 shows a relationship between a track (head traveling locus) and a rotary head during insert recording in a conventional magnetic recording apparatus. Here, when a rotary head (head width = Hw) having a head width wider than the track pitch (= Tw) recorded on the magnetic tape is used, and the insert recording is performed by this rotary head, at the start of insertion and the end of insertion, The relationship between the track on the magnetic tape and the rotary head is shown.

In a system such as a magnetic recording / reproducing apparatus such as a video tape recorder (VTR) for recording / reproducing on / from a magnetic tape using a rotary head, the tape running speed of the magnetic tape 11 and the rotation of the rotary heads 12, 13 are increased. From speed,
The recording track width on the magnetic tape 11 during recording is determined. In normal recording, since the running speed of the tape 11 and the rotating speeds of the rotary heads 12 and 13 are kept constant, the track width is always constant. Then, only the last track has the same track width as the head width Hw.

On the other hand, even in the insert recording, the track 14 from the start of the insert to the track one track before the end of the insert has a regular track pitch Tw. The last track 15 has the same track width as the head width (that is, Hw). However, since there is a part that has been recorded before the insertion following the inserted part, only the first track 16 of this part is erased because the last track 15 of the insert part is wider than the regular track width. It becomes narrow. If the track width of this portion is Tx, Tx is given by the following equation.

Tx = 2 × Tw−Hw FIG. 5 shows VHS (Video Home Syste) during insert recording.
FIG. 6 is a diagram showing the relationship between the track and the rotary head in the standard mode of the m) system, and FIG. 6 is a diagram showing the relationship between the track and the rotary head in the triple mode of the VHS system. In these figures, the same parts as those in FIG. 4 are designated by the same reference numerals.

As shown in FIG. 5, the track pitch Tw is about 60 μm in the VHS standard mode, and the rotary head width Hw is taken into consideration in consideration of compatibility such as linearity and head step.
Is 65 μm, which is wider than the track width Tw by 5 μm, Tx = 55 μm.

Similarly, as shown in FIG.
In the double mode, the track pitch Tw is about 20 μm,
Rotating head width Hw is 25μ considering compatibility with other models
When m, Tx = 15 μm.

Here, the above-mentioned difference between the head width Hw and the track width Tw (5 μm in this example) is not so much dependent on the size of the head width Hw because the required amount is determined by the mechanical accuracy at the time of compatibility. .

Next, considering the case of reproducing these tracks, in the standard mode, as shown in FIG. 5, even if the normal track 14 becomes 60 μm, only the next first track 16 becomes 55 μm. The track width is wide enough and there is no obstacle to playback. Also, in the triple mode, as shown in FIG.
As shown in FIG. 5, the normal track 14 is 20 μm and the first track 16 is 15 μm, so that the C / N ratio of the head output is deteriorated by about 2.5 dB, and the image quality is deteriorated in this portion. However, reproduction is possible regardless of the image quality. In such a wide track system, reproduction was possible even with some influence.

However, in recent years, with the progress of high-density recording, the track width further decreases and becomes 10 μm or less.
If the head width is wider than the track width by about 5 μm, the first track width Tx after the end of the insert recording is considerably narrowed, a sufficient head reproduction output cannot be obtained, and finally the reproduction becomes impossible. there were.

As a countermeasure against this, conventionally, the head width Hw was made as close as possible to the track pitch Tw to widen Tx, but in consideration of compatibility, it is not possible to completely match the widths of Hw and Tw. It wasn't a good solution.

[0013]

As described above, in a magnetic recording system having a narrow track width as high-density recording progresses, there is a problem that unreproducible tracks are generated during insert recording. However, it was not possible to fully satisfy the compatibility with other models.

Therefore, in view of the above problems, the present invention satisfies the compatibility even in a magnetic recording system having a narrow track width, and a helical scan system in which an unreproducible track does not occur during insert recording. It is an object of the present invention to provide a magnetic recording device.

[0015]

SUMMARY OF THE INVENTION The present invention provides a helical scan type magnetic recording apparatus for running a magnetic tape by using a capstan and recording a signal on the magnetic tape by using a rotary head. A rotary head having a head width wider than the pitch of the track recorded above, an operating means for designating insert recording, a means for generating an insert mode signal during a predetermined period designated by this operating means, and this insert mode. Based on the signal
Means for generating an insert end signal indicating a transition from the insert mode to the stop mode, means for generating a mute signal for performing recording mute at the end of the insert based on the insert mode signal, and the rotation by the mute signal. A means for turning off the recording signal supply to the head, a means for generating a timing signal preceding by a few tracks immediately before the end of the insertion based on the insert mode signal, and a rotational speed of the capstan. Based on the timing signal preceding by a few tracks immediately before the end of the insert and the mute signal, the capstan speed is reduced to reduce the track pitch by a few tracks immediately before the end of the insert to be smaller than the regular width, and The capstan is stopped based on the insert end signal. It is characterized in that it has and a that means.

[0016]

In the present invention, by detecting the period of several tracks immediately before the end of the insert, the capstan speed is reduced at a constant rate for the period of several tracks immediately before the end of the insert, and the tape running speed is lowered. As a result, the track pitch is narrowed for a few tracks before the end of the insert so that the initial track width after the end of the insert is not significantly narrowed.

[0017]

EXAMPLES Examples will be described with reference to the drawings. FIG. 1 is a block diagram showing a helical scan type magnetic recording apparatus according to an embodiment of the present invention.

In FIG. 1, the operation keys 21 are a play button (PLAY), a stop button (STOP), an insert button, a record button (REC), and a rewind button (RE).
W), fast forward button (FF), pause button (PAU)
It has buttons such as SE). The operation key 21 is connected to the key scan microcomputer 22. The key scan microcomputer 22 determines which one of the operation buttons 21 is pressed, selects a mode such as a reproduction mode or an insert mode based on the result, and inserts the end detection circuit 23, the motor / mechanical control circuit 24, and A mode signal is sent to the recording mute control circuit 31. In accordance with this mode signal, the motor / mechanical control circuit 24, the capstan motor drive circuit 25, the cylinder motor drive circuit 2
6, via the reel motor drive circuit 27, capstan motor 28, cylinder motor 29, reel motor 3
It controls the operation of each motor such as 0, loading arm, pinch roller, and other mechanisms. The capstan motor drive circuit 25, the cylinder motor drive circuit 26, and the reel motor drive circuit 27 actually drive each motor based on the mode signal from the motor / mechanical control circuit 24, and apply a servo.

Further, the recording mute control circuit 31 determines the generation timing of the recording mute signal necessary for the end of the insertion by the mode signal from the key scan microcomputer 22 and changes the track pitch which rises several tracks before the recording mute signal. A signal for instructing (called a track pitch change signal) is output. The recording mute signal output from the recording mute control circuit 31 is input to the recording amplifier 33. The recording amplifier 33 controls whether to record the recording signal 34 according to the recording mute signal. Further, the track pitch change signal output from the recording mute control circuit 31 is input to the capstan speed control circuit 32.

On the other hand, the insert end detection circuit 23 receives a mode signal from the key scan microcomputer 22 and generates an insert end signal when shifting from the insert mode to the stop mode (that is, the insert end). This insert end signal is input to the capstan speed control circuit 32. The capstan speed control circuit 32 generates a control signal for reducing the capstan speed for a certain period (several tracks) based on the recording mute signal and the track pitch change signal. This control signal is applied to the capstan drive circuit 25 to reduce the rotational speed of the capstan for a certain period (several tracks) before the end of the insertion.

Next, the operation of FIG. 1 will be described with reference to FIGS. FIG. 2 shows changes in signals at various portions of the circuit of FIG. 1 and the rotational speed of the capstan motor during insert recording.

FIG. 2A shows a recording mute signal at the end of insertion. When the recording mute signal goes high, the recording amplifier 33 turns off the supply of the recording signal 34 to the magnetic tape 36, and the insert recording ends. FIG. 2 (b) shows a track pitch changing signal, which is a signal which becomes high level several tracks earlier than the recording mute signal of FIG. 2 (a). FIG. 2C shows the output of the capstan speed control circuit 32. The capstan control circuit 32 produces a signal that changes from the recording mute signal and the track pitch change signal shown in FIGS. 2A and 2B for a period (t1 to t2) of several tracks immediately before the end of the insertion.
When FIG. 2 (c) is input to the capstan motor drive circuit 25, as shown in FIG. 2 (d), immediately before the end of insertion,
The rotation speed of the capstan motor 28 decreases only for a period of several tracks. Assuming that the motor rotation speed of a normal truck is V, the motor rotation speed of several tracks before the end of insertion is reduced to 0.8 to 0.9V. As a result, the track pitch becomes narrower for a few track periods before the end of the insert.

The state of the tracks on the tape at this time is shown in FIG.
Will be described with reference to. FIG. 3 shows the relationship between the track and the rotary head during insert recording.

In FIG. 3, 36 is a magnetic tape, and 35, 35 '.
Is a rotary head, 41 is a normal track for insert recording, 42 is the last track for insert recording, 43 is the first track after the end of insert recording, and 44 is a track of the portion where the tape running speed is slowed down just before the end of insert recording. Shows. Since the capstan speed after time t1 (corresponding to t1 in FIG. 2 (c)) decreases, the track 44 (track shown by the solid line in FIG. 3) at this time is at the normal position (indicated by the dotted line in FIG. 3). It gradually deviates from the indicated track). At this time, since the head speed becomes relatively faster than the tape speed, the track pitch is narrow. When the recording mute signal becomes high level at time t2 (corresponding to t2 in FIG. 2 (c)), the recording signal is not supplied to the rotary heads 35, 35 ', and the insert recording ends. And the first track 4 after the end of insert recording
3 becomes wider as the number of tracks just before the end of insertion becomes narrower, and the track width becomes reproducible.

For example, in the insert recording, if the width of the normal track is 10 μm and the width of the last track of the insert recording is 14 μm, the width of the first track after the end of the insert recording is 6 μm. When the capstan speed is decelerated by 10% for a period of, for example, 3 tracks before the end of the insert, the width of the normal track is 10 μm, and the width of each of the three tracks during the deceleration period of the capstan is 9 μm. Even if the track width is 14 μm, the width of the first track after the end of insert recording is 9 μm, which is a reproducible track width.

[0026]

As described above, according to the present invention, an unreproducible track does not occur immediately after the end of insertion,
Even in a recording / reproducing system with a narrow track width, insert recording can be performed with a rotary head wider than the track width.

[Brief description of drawings]

FIG. 1 is a block diagram showing a helical scan type magnetic recording apparatus according to an embodiment of the present invention.

FIG. 2 is a timing chart illustrating the operation of FIG.

3 is a diagram showing a relationship between a track and a rotary head during insert recording in the apparatus shown in FIG.

FIG. 4 is a diagram showing a relationship between a track and a rotary head during insert recording in a conventional apparatus.

FIG. 5 is a VHS system (standard mode) in a conventional device.
FIG. 5 is a diagram showing the relationship between the track and the rotary head.

FIG. 6 is a VHS system (triple mode) in a conventional device.
FIG. 5 is a diagram showing the relationship between the track and the rotary head.

[Explanation of symbols]

 21 ... Operation key 22 ... Key scan microcomputer 23 ... Insert end detection circuit 25 ... Capstan motor drive circuit 31 ... Recording mute control circuit 32 ... Capstan speed control circuit 33 ... Recording amplifier 35 ... Rotating head 36 ... Magnetic tape

Claims (1)

[Claims] 1. A helical scan type magnetic recording apparatus for recording a signal on a magnetic tape by using a rotary head while running the magnetic tape using a capstan. The pitch of tracks recorded on the magnetic tape. A rotary head with a wider head width, an operation means for specifying insert recording, a means for generating an insert mode signal during a predetermined period specified by this operation means, and a stop from the insert mode based on this insert mode signal. Means for generating an insert end signal indicating transition to the mode, means for generating a mute signal for performing recording mute at the end of the insert based on the insert mode signal, and recording to the rotary head by the mute signal Means for turning off the signal supply, the insert mode signal Based on the above, a means for generating a timing signal preceding by a few tracks immediately before the end of the insert, and a means for controlling the rotation speed of the capstan, the timing signal preceding by a few tracks immediately before the end of the insert, and the mute A means for decelerating the capstan speed in order to make the track pitch narrower than the regular width for a few tracks immediately before the end of the insert based on the signal, and for stopping the capstan based on the insert end signal. Helical scan type magnetic recording device.