JPH1145480A - Recording or playback device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To enable good reproduction of a distorted track. SOLUTION: A peak detector 24 detects peaks of an output of a preamplifier 22 at three points at the beginning, middle and end of a track. The comparison circuit 28 detects the three detection outputs A,
B and C are compared, and the differences ΔT (= BA) and ΔE (= B−
C) is applied to the microcomputer 30. The microcomputer 30 is designed to reduce ΔT and ΔE,
The stepping motors 18 and 20 are rotated via the motor driving circuits 32 and 34 to adjust the heights of the inlet post 14 and the outlet post 16.

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 recording or reproducing apparatus.

[0002]

2. Description of the Related Art In a conventional recording or reproducing apparatus of the helical scan system, for example, a VTR, the envelope output when a compatible tape is reproduced depends only on the linearity of the track. Therefore, when a tape recorded by another device is reproduced, if the linearity of the track is deviated, the amplitude of the envelope output, particularly at the entrance and exit, becomes extremely small.

FIG. 2 shows a track pattern distorted on the entrance side, and FIG. 3 shows its envelope output.
FIG. 3A shows a preamplifier output of the reproducing head, and FIG. 3B shows a head switching pulse. FIG. 4 shows a track pattern distorted on the exit side, and FIG. 5 shows its envelope output. FIG. 5A shows a preamplifier output of the reproducing head, and FIG. 5B shows a head switching pulse. FIG. 6 shows a track pattern greatly distorted on the exit side, and FIG. 7 shows its envelope output. 7A shows a preamplifier output of the reproducing head, and FIG. 7B shows a head switching pulse.

In recent years, in order to increase the recording density, the track width has become narrower, making it difficult to maintain compatibility with other devices.

[0005]

However, in the conventional example,
Since the envelope output at the time of compatible reproduction relies only on the linearity of the track, the output at the entrance and / or the exit side of the rotary head is extremely small or sometimes missing.

In addition, when insert recording or post-recording is performed on an already recorded tape, there is a drawback that the already recorded track cannot be matched with the newly recorded track.

Further, in recent years, the track width has been reduced in order to increase the recording density, and it has become difficult to maintain compatibility with other devices.

[0008] It is an object of the present invention to provide a recording or reproducing apparatus which improves track following performance during recording or reproducing.

It is another object of the present invention to provide a recording or reproducing apparatus capable of obtaining a flat envelope output as a whole at the time of reproduction, or capable of performing recording in conformity with a recorded medium.

[0010]

According to the present invention, in a helical scan type recording or reproducing apparatus, a detecting means for detecting peaks at a plurality of points of a reproduced envelope output is compared with a detecting output of the detecting means. Means are provided, and at least one of the entrance side post and the exit side post of the rotary drum is a movable post, and the height of the movable post is adjusted according to the output of the comparison means.

According to the present invention, in a recording or reproducing apparatus of the helical scan system, a plurality of points of a reproduced envelope output are peak-detected, and a tracking position of a rotary head with respect to a target track is determined so that each detected output is equalized. The adjustment is performed in the longitudinal direction of the tape.

This makes it possible to optimize the trace of the rotary head with respect to the distortion of the track, and to prevent the reproduction output from becoming extremely weak or missing. Also, the reproduction envelope output becomes flatter. Further, it is possible to perform recording with consistency with tracks on a medium on which recording has already been performed.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic block diagram showing an embodiment of the present invention. 10 is a magnetic tape, 12 is a rotating drum,
14 is an inlet post of the rotary drum 12, 16 is an outlet post of the rotary drum 12, 18 is a stepping motor for changing the height of the inlet post 14, and 20 is a stepper motor for changing the height of the outlet post 16. Motor 22,
Reproducing head (not shown) mounted on rotating drum 12
A detector for amplifying the output of the preamplifier, a detector for peak detecting the output level of the preamplifier at a plurality of predetermined timings (specifically, three points at the beginning, middle, and end of a track); A signal processing circuit for reproducing sound; 28, a comparator for comparing the two outputs of the detector 24; 30, a microcomputer for determining the deviation of the track linearity from the comparison result of the comparator 28; , A motor drive circuit for driving the stepping motors 18 and 20 in accordance with the output of the microcomputer 30.

The operation of the embodiment shown in FIG. 1 will be described in detail. In the present embodiment, as shown in FIG. 8, the peak detection circuit 24 detects the peak values A, B, and C of the output of the preamplifier 22 at three points at the beginning, middle, and end of one track, and the comparison circuit 28 , And calculate the difference B−A, B−C.
The microcomputer 30 calculates ΔT (= BA) and ΔE
In accordance with (B-C), the motor driving circuits 32 and 34 are controlled to adjust the heights of the posts 14 and 16 so that the output level of the preamplifier 22 is flattened.

FIG. 9 shows a flowchart for adjusting the height of the post 14 on the drum entrance side. It is. It is checked whether ΔT is equal to or lower than a specified level (S1). If ΔT is equal to or lower than the specified level, the process ends. When ΔT exceeds the prescribed level, the post 14 is slightly rotated in the forward direction by a predetermined angle to slightly shift the magnetic tape 10 upward (or downward) (S2), and in that state, ΔT increases. It is checked whether or not (S3). As a result, if the level of ΔT is small (S3), the post 14 is moved in a preferable direction.
Is adjusted, and it is checked whether the height adjustment is the upper limit (S4). If the upper limit is reached, the process ends. If the upper limit is not reached, the process returns to S1 and the adjustment is performed. continue.

If ΔT increases in the forward rotation (S3), the rotation direction of the post 14 is reversed, and the motor 18 of the post 14 is rotated in the reverse direction by a predetermined angle (S5). Then, it is determined whether ΔT is equal to or less than a specified level (S6).
If it exceeds the prescribed level, it is confirmed whether or not it is the upper limit of height adjustment (S6). If the height adjustment upper limit has been reached (S
7) When the adjustment is completed and the upper limit is not reached (S
7) Then, the motor 18 of the post 14 is again rotated by a predetermined angle (S5), and the height adjustment of the post 14 is repeated.

If the linearity on the outlet side of the rotary drum 12 is distorted, the height of the post 16 is adjusted with respect to ΔE by the same algorithm as in FIG.

As described above, in this embodiment, even if the track pattern is distorted on the entrance side and / or the exit side of the drum, the height of the posts 14, 16 is adjusted according to the distortion. Make the head follow the track.
Thus, a good envelope output can be obtained regardless of the distortion of the track pattern.

In the flowchart shown in FIG. 9, the heights of the posts 14 and 16 are dynamically adjusted at a distorted portion of the track. However, the trace position of the magnetic head with respect to the track is adjusted so as to obtain an average envelope output. May be shifted uniformly. FIG. 10 shows the flowchart. As shown in FIG. 11, the magnetic head is shifted to a curved track of a track having poor linearity. FIG. 12A shows a preamplifier output for the head trace shown in FIG. 11, and FIG. 12B shows a head switching pulse.

It is checked whether ΔT is equal to or less than a specified level (S
11) If the level is equal to or lower than the specified level, the process ends.
If ΔT exceeds the specified level (S11), the magnetic tape 1
The feed speed of 0 is finely adjusted by, for example, a capstan motor (not shown) to slightly shift the tracking in the advancing direction (S12). In this state, it is checked whether ΔT becomes large (S13). If the level of ΔT becomes small (S13), it means that the head trace is being adjusted in a preferable direction. Check (S14). If the upper limit has been reached, the process ends. If the upper limit has not been reached, the process returns to S11 to continue the adjustment.

If ΔT increases due to the tracking shift (S13), the shift direction is reversed, so that the tracking is shifted in the delay direction (S1).
5). Then, it is checked whether or not ΔT is equal to or less than a specified level (S16). If ΔT is equal to or smaller than the specified level, the process is terminated. If the upper limit of the tracking shift has been reached (S17), the adjustment is terminated, and if the upper limit has not been reached (S17), the adjustment after S15 is repeated again.

In this way, even with the algorithm shown in FIG. 10, even if a track having poor linearity is reproduced, the lack of the envelope output can be prevented, and the averaged envelope output can be obtained as much as possible.

In the control algorithm shown in FIG. 9 as well, if the time constant of the height adjustment of the posts 14 and 16 is lengthened, the curved track is changed so that the envelope output has an average size from the beginning to the end of the track. The magnetic head traces linearly so that
The operation and effect are the same as those in the control flowchart shown in FIG.

[0025]

As can be easily understood from the above description, according to the present invention, a good envelope output can be obtained even if a tape having poor linearity is reproduced.
In addition, the envelope output can be averaged, and the output can be made flatter. Further, it is possible to realize consistent recording even on a medium that has already been recorded. Although the overall C / N ratio is reduced, the missing portion of the reproduction output is eliminated, which is particularly effective for a device for performing digital recording and reproduction.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of an embodiment of the present invention.

FIG. 2 is a track pattern diagram when the linearity on the drum entrance side is shifted.

FIG. 3 is a reproduction output waveform for the track pattern shown in FIG. 2;

FIG. 4 is a track pattern diagram when the linearity on the drum exit side is shifted.

FIG. 5 is a reproduction output waveform for the track pattern shown in FIG. 4;

FIG. 6 is a track pattern diagram when the linearity on the drum exit side is largely shifted.

FIG. 7 is a reproduction output waveform for the track pattern shown in FIG. 6;

FIG. 8 is a diagram illustrating an envelope detection position according to the present embodiment.

FIG. 9 is a flowchart of the present embodiment.

FIG. 10 is a flowchart of a second embodiment of the present invention.

11 is a diagram showing a tracking position in the embodiment shown in FIG.

12 is a reproduction output waveform corresponding to the track pattern shown in FIG.

[Explanation of symbols]

 10: Magnetic tape 12: Rotating drum 14: Inlet side post 16: Outlet side post 18, 20: Stepping motor 22: Preamplifier 24: Detector 26: Signal processing circuit 28: Comparator 30: Microcomputer 32, 34: Motor Drive circuit

Continued on the front page (51) Int.Cl. ⁶ Identification code FI H04N 5/7826 H04N 5/783 5/783 5/782 G

Claims (4)

[Claims] 1. A recording or reproducing apparatus of a helical scan system, comprising: detecting means for detecting peaks at a plurality of positions of a reproduced envelope output; and comparing means for comparing the detected outputs of the detecting means. At least one of the inlet post and the outlet post of the rotary drum is a movable post, and the height of the movable post is adjusted according to the output of the comparing means. 2. The detecting means includes: an inlet side of a rotary head;
The envelope output is detected at the exit side and at three places near the center.If the detection output on the entrance side is extremely small with respect to the detection output on the center, the height of the post on the entrance side of the rotary head is changed, and The recording or reproducing apparatus according to claim 1, wherein when the detection output on the exit side is extremely small with respect to the detection output, the height of the exit post on the rotary head is changed. 3. The recording or reproducing apparatus according to claim 1, wherein an upper limit is set for height adjustment of the entrance side post and the exit side post. 4. A recording or reproducing apparatus of a helical scan system, wherein a plurality of points of a reproduced envelope output are peak detected, and a tracking position of a reproducing head with respect to a target track is taped so that each detected output is equalized. A recording or reproducing apparatus characterized in that adjustment is made in the longitudinal direction of the recording or reproducing apparatus.