JP2854156B2 - Auto tracking device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic tracking control device for controlling a video signal and an audio signal of a HiFi VTR to the best tracking position.

[0002]

2. Description of the Related Art VHS (registered trademark) HiFi VTR
Adopts the so-called audio signal deep recording method of recording the audio signal on the horizontal track established on the magnetic tape, recording the video signal on the surface layer of the inclined track of the magnetic tape, and recording the audio signal on the deep layer. In the deep recording method, a video head and an audio head are arranged on a rotary head cylinder,
This is a system for recording and reproducing respective signals by the respective heads.

For this reason, in the tracking control at the time of reproducing the video signal and the audio signal recorded on the inclined track of the magnetic tape, the self-recording reproduction (that is, reproduction by the same VTR as the VTR recorded on the magnetic tape) is performed at the tracking position. Are controlled near their respective envelope maximum values. That is, the same VTR
Since the position difference between the envelope maximum value of the video signal and the audio signal with respect to the tracking control position becomes smaller in the self-recording / reproducing, the image quality at the time of reproduction based on the deviation between the position of each envelope maximum value and the tracking control position is reduced, and There is no problem of sound quality deterioration.

However, in other-self-recording reproduction (that is, reproduction is performed on a VTR different from the VTR recorded on the magnetic tape), the identity between the VTRs is lost due to variations in the width of the head track, head track width, and head attachment, and tracking control is performed. The position difference between the envelope maximum values of the video signal and the audio signal becomes larger than the position. That is, a general HiFi VTR is
Differences between the width of the video magnetic head (about 40 to 58 μm) and the width of the audio magnetic head (about 26 to 28 μm) based on the VTR manufacturer's magnetic head specifications, When tracking control is performed in accordance with the position of the maximum envelope value of the video signal and the audio signal during reproduction due to variations or the like based on the mounting tolerance of the head, the image quality of the video is degraded or reduced depending on the tracking control position and each envelope level. Causes the sound quality of the voice to deteriorate.

For this reason, the conventional auto tracking (hereinafter abbreviated as ATR) control adds a coefficient (weighting) at a fixed ratio (for example, 1: 1) to the position difference between the envelope maximum values of the video signal and the audio signal. ATR control for controlling the tracking control position to be an intermediate position with respect to the position of each envelope level maximum value is generally used.

FIG. 4 shows ATR control according to a conventional example, and the envelope change characteristics of each of video and audio and the tracking position control will be described based on the principle of operation.

In FIG. 4, the vertical axis indicates the relationship between the envelope output level based on the envelope change characteristics of the video and audio. The noise generation limit based on the envelope level is VG for the video signal and AG for the audio signal. . The horizontal axis indicates the relationship between the tracking amounts of the respective video and audio tracking control positions. The position of the maximum envelope level based on the tracking amounts is a video signal TV, an audio signal TA, and the tracking control position. Let it be To.

FIG. 4A shows a case where the positions of the maximum values of the envelope levels of the video signal and the audio signal match, and shows that the tracking control position matches the position of the maximum value of each envelope level. Each of B, C, and D in FIG. 4 is a case where there is a position difference between the maximum values of the envelope levels of the video signal and the audio signal, and based on the coefficient for the position difference, the intermediate position between the video signal and the audio signal is determined. FIG. 4B shows that tracking control is performed, and the tracking control position is at the limit of noise generation at the envelope level of the audio signal. In FIG. 4C, the tracking control position is at a position beyond the noise generation limit of the envelope level of the audio signal. At this time, the envelope level of the video signal is 70 to 80% of the maximum value level. Further, the tracking control position in FIG. 4D is a case where a position difference between the maximum value of each envelope level occurs further than in FIG. 4C, and the envelope level of the video signal is at the limit point of noise generation. Noise occurs and the image quality deteriorates.

In contrast to the drawbacks caused by such tracking position control, the conventional ATR control further includes a case where the tracking control position exceeds a limit point at which noise occurs for each envelope level of the video signal or the audio signal (mainly, the tracking position of the audio signal). The above problem is solved by controlling the switching of the reproduced sound from the inclined track to the sound signal by the horizontal track.

[0010]

However, even with the above-mentioned ATR control, the envelope change characteristics of the video signal and the audio signal have an advantageous relationship with the video signal (that is, the envelope change characteristics reaching a limit point at which noise occurs with respect to the envelope level). Is larger in the video signal than in the audio signal.) Therefore, as the position difference between the maximum values of the envelope levels increases, the sound becomes disadvantageous to the generation of noise and the deterioration of the sound quality. Further, since the tracking control position of the ATR control and the position of the maximum envelope level of the video signal are unnecessarily separated, noise is also generated in the reproduced image.

Then, as shown in FIG. 4D, the positions of the maximum values of the envelope levels are greatly separated from each other, and the envelope levels due to the tracking control positions are such that the video signal is at the noise generation limit and the audio signal is the noise generation limit. When it is located beyond the position, the audio signal is controlled to be switched from the audio signal by the inclined track to the audio signal by the horizontal track. At this time, the tracking control position of the video signal is fixed to the envelope level at the noise generation limit point. There has been a problem that preventing the deterioration of the image quality of the reproduced image due to this is also a problem.

Accordingly, the present invention has been made to solve the above-mentioned problem, and an object of the present invention is to provide a video head having a wider track width than an audio head and having a margin in a video tracking control range with respect to a tracking position shift. Attention is paid to detecting the positions of the maximum values of the envelope levels of the video signal and the audio signal, respectively, and detecting a limit point at which noise occurs at each of the envelope levels (for example, 60 to 90 of the maximum envelope level for the video signal). 70%, for audio signals 70 to 80 of the maximum envelope level
%) And detects this, and determines the maximum value of each envelope level and the amount of tracking deviation at the position of the maximum value within a predetermined range. Based on the amount of tracking deviation, the video signal and the audio signal are determined. A predetermined coefficient (weighting) is added to the tracking change amount in each envelope change characteristic of the signal, and when the tracking shift amount is within a predetermined range according to the position difference between the envelope level maximum values, the audio signal The tracking position is controlled by giving priority to the tracking change amount over the video signal tracking change amount.If the tracking deviation exceeds a predetermined range, the tracking position is controlled to the position of the maximum envelope level of the video signal and the horizontal track is controlled. To provide an auto-tracking device that controls switching to a reproduced audio signal A.

[0013]

Therefore, according to the present invention, an audio signal reproduced from a horizontal track of a recording medium, a video signal reproduced from an inclined track of a recording medium, and a Hi signal are reproduced.
An auto-tracking device for controlling the best tracking position based on the Fi audio signal and the video signal and the HiFi audio signal, a means for detecting a tracking best position of each envelope level of the video signal and the HiFi audio signal, respectively; Means for detecting a tracking limit point of an envelope level of a signal, and a predetermined count for a tracking change amount in each envelope characteristic of the video signal and the HiFi audio signal based on a deviation amount between the best position of the video signal and the best position of the HiFi audio signal. The tracking position is controlled based on the count added by the counting addition unit, and when the tracking position of the HiFi audio signal exceeds the limit point, the tracking position is set to the best position of the video signal. Control and HiFi voice communication And wherein the switching to the audio signal reproduced from the horizontal tracks Disable.

[0014]

As described above, according to the present invention, a limit point of each envelope level of a video signal and an audio signal is detected, a position difference between the maximum values of the envelope levels is detected, and a video signal is detected based on the limit point of each envelope level. A predetermined coefficient (weighting) is added to each tracking change amount of the audio signal and the audio signal, and the tracking position is controlled according to the position difference between the envelope level maximum values. The tracking position can be controlled to the best practical position in accordance with the envelope levels of the signal and the audio signal.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram illustrating the principle of operation according to the ATR control of the present invention,
FIG. 2 is a circuit block diagram of an ATR control device according to an embodiment of the present invention, FIG. 3 is an operation functional block diagram of the tracking microcomputer of FIG. 2, and FIG.

First, the ATR control by the tracking microcomputer of the present invention shown in FIG. 1 will be described with reference to the principle of operation of the envelope change characteristics of video and audio and the tracking position control, as in the conventional example.

FIG. 1A shows a case where the position of the maximum value of each envelope level of the video signal and the audio signal coincides, and shows that the tracking control position coincides with the position of the maximum value of each envelope level. Both B and C in FIG. 1 are cases where there is a position difference between the maximum values of the envelope levels of the video signal and the audio signal, and tracking control is performed on each of the video signal and the audio signal based on a predetermined coefficient. FIG. 1B shows the tracking control in which the tracking control position gives priority to the envelope change characteristic of the audio signal over the video signal. In FIG. 1C, the tracking control position is at the limit of noise generation of the envelope level of the audio signal, and the envelope level of the video signal at this time is 60 to 70% of the maximum value level.

The tracking control shown in FIG. 1D controls the tracking control position to the position of the maximum envelope level of the video signal when a positional deviation occurs between the envelope level and the maximum value of each envelope level as compared with FIG. 1C. At the same time, tracking control of the audio signal is invalidated, and switching to the audio signal by the horizontal track is controlled.

Next, a description will be given with reference to a circuit block diagram of the ATR control device with reference to FIG.

In the drawing, 1 is a fixed head for recording and reproducing AM audio signals, 2 is a rotary head for recording and reproducing FM audio signals, 3
Is a rotary head for recording and reproducing video signals, 4 is a preamplifier for amplifying the reproduction output of the FM audio signal by the rotary head 2, and 5 is a preamplifier for amplifying the reproduction output of the video signal by the rotary head 3.

As the audio signal reproduced by the fixed head 1, an AM audio signal recorded on a horizontal track of a magnetic tape by a normal audio signal processing section 6 is output to a switch circuit 20 based on fixed tracking position control.

The FM audio signal recorded on the inclined track of the magnetic tape is reproduced by the rotary head 2 and amplified by the preamplifier 4, and then one of them is output to an audio envelope detection circuit 7, and the other is output to the audio envelope detection circuit 7. As a result, the FM audio signal is detected at the envelope level.
The other is output to the FM audio signal processing unit 8, the FM audio signal processing unit performs FM demodulation processing on the FM audio signal, and also discriminates the FM audio signal to generate a discrimination control signal indicating FM sound or normal sound. . The audio signal subjected to the FM demodulation processing is output to the switch circuit 20.

After the video signal recorded on the inclined track of the magnetic tape is reproduced by the rotary head 3 and amplified by the preamplifier 5, one of the video signals is output to a video envelope detection circuit 9, and the other is output by the video envelope detection circuit. The video signal is detected at the envelope level. The other is output to the video signal processing unit 10, where the video signal is subjected to FM demodulation processing and reproduced and output.

The audio signal detected to the envelope level by the audio envelope detection circuit 7 and the F
The discrimination control signal for instructing the FM audio or the normal audio generated by the M audio signal processing unit 8 and the video signal detected to the envelope level by the video envelope detection circuit 9 are input to the tracking microcomputer 30 , respectively. Then, the tracking microcomputer 30 performs a video and audio tracking control process when the reproduced audio is determined to be a normal audio signal, and a video and audio tracking control process when the reproduced audio is determined to be the FM audio signal.

Next, the tracking position control by the tracking microcomputer 30 will be described with reference to the operation function block diagram of FIG.

The video envelope signal input from the video envelope detection circuit 9 is input to a video tracking position detecting section 31, and the tracking position detecting section detects the position of the maximum envelope level based on the change characteristic of the video envelope signal. A tracking amount based on the position is detected. Based on these data, the video tracking position detecting unit 31 sets a limit point of an envelope level at which noise occurs in a video signal with respect to the level of the envelope level maximum value (in the embodiment, 60% to 60%).
The tracking amount at the position of the envelope level maximum value is output to a tracking position control unit 38, which will be described later, and the envelope level of the video signal is detected. The position difference is also output to a position difference detection unit 33 which detects a position difference between the position of the value and the position of the envelope level maximum value of the audio signal, and the respective data by the position difference detection unit 33 and the video envelope limit point detection unit 32 are Is input to a tracking shift amount determination unit 36 described later.

The audio envelope signal input from the audio envelope detection circuit 7 is also input to the audio tracking position detector 34 in the same manner as the video envelope signal, and the tracking position detector detects the change characteristic of the audio envelope signal. Based on this, the position of the envelope level maximum value and the tracking amount based on the position are detected. Based on these data, the audio tracking position detection unit 34 sets a limit point of the envelope level at which noise occurs in the audio signal with respect to the level of the envelope level maximum value (70% to 80% in the embodiment). Voice envelope limit point detector 35 for detecting a limit point
In addition, the tracking amount at the position of the envelope level maximum value is made to a tracking position control unit 38 described later, and the position difference between the position of the envelope level maximum value of the video signal and the position of the envelope level maximum value of the audio signal is calculated. The data is also output to the position difference detection unit 33 to be detected, and the respective data by the position difference detection unit 33 and the audio envelope limit point detection unit 35 are input to a tracking shift amount determination unit 36 described later.

The tracking shift amount judging section 36 inputs data of the position difference between the envelope level limit point and the maximum value of the video signal and the audio signal, and the tracking amount shift is arbitrarily set based on the data. The difference between the small tracking amount indicating that the deviation of the tracking amount is within the predetermined range and the large amount of deviation indicating that the deviation of the tracking amount exceeds the predetermined range. Generate a signal. The large shift amount signal is output to the FM / normal switching control unit 37 and the tracking position control unit 38, and the small shift amount signal is output to the tracking position control unit 38.

The FM / normal switching control unit 37 includes:
A discrimination control signal output from the FM audio signal processing unit 8 and a large displacement amount signal by the comparison discrimination are input, and when the large displacement amount signal and the discrimination control signal indicate a normal voice, the audio output is inclined. An audio output switching signal for switching from an audio signal reproduced from a track to an audio signal reproduced from a horizontal track is generated and output to the switch circuit 20.

The tracking position control unit 38
The tracking amount at the position of each envelope level maximum value is input from the video tracking position detecting unit 31 and the audio tracking position detecting unit 34, and the large displacement amount signal or small displacement amount signal by the comparison determination is input. When the deviation amount is a small signal based on the deviation amount of the tracking, a predetermined coefficient (for example, in this embodiment, the amount of change of the audio is changed with respect to the amount of change of the image 2). In the case of the large displacement amount signal, the tracking position is controlled to the tracking position based on the tracking amount of the position of the maximum envelope level by the video tracking position detection unit 31 and the audio tracking is performed. The data relating to the position detection unit 34 and the tracking amount is invalidated.

Tracking position control data at the time of the small deviation amount signal by the tracking position control unit 38;
The tracking position control data at the time of the small deviation amount signal is output as a control signal for a capstan motor or the like to a servo circuit that controls the tape traveling drive of the magnetic tape (not shown).

[0032]

As described above, the present invention detects the position of the maximum value of each of the envelope levels of the video signal and the audio signal and detects the limit point (for example, the video signal) at each of the envelope levels. (60-70% of the envelope maximum level, and 70-80% of the envelope maximum level for the audio signal), and detects this. And a predetermined coefficient (weighting) is added to the tracking change amount in each of the envelope change characteristics of the video signal and the audio signal based on the limit point of each of the envelope levels.
When the deviation of the tracking amount is within a predetermined range according to the position difference between the envelope level maximum values, the tracking position is controlled by giving priority to the tracking change amount of the audio signal over the tracking change amount of the video signal. When the deviation exceeds a predetermined range, the tracking position is controlled to the position of the maximum envelope level of the video signal and the switching to the audio signal reproduced from the horizontal track is performed. It is possible to control the tracking position to be practically the best in accordance with each envelope level of the video signal and the audio signal. When playing back a tape, minimize the deterioration of image quality and sound quality due to the tracking position shift. Can.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an operation principle based on auto tracking (ATR) control of the present invention.

FIG. 2 is a circuit block diagram of an ATR control device according to one embodiment of the present invention.

FIG. 3 is a functional block diagram of the tracking microcomputer of FIG. 2;

FIG. 4 is a diagram for explaining the principle of operation by ATR control in a conventional example.

[Explanation of symbols]

Reference Signs List 6 normal audio signal processing section 7 audio envelope detection circuit 8 FM audio signal processing section 9 video envelope detection circuit 10 video signal processing section 20 switch circuit 30 tracking microcomputer 31 video tracking position detection section 32 video envelope limit point detection section 33 position difference detection Unit 34 audio tracking position detection unit 35 audio envelope limit point detection unit 36 tracking deviation amount determination unit 37 FM / normal switching control unit 38 tracking position control unit

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G11B 15/467

Claims (1)

(57) [Claims] 1. An audio signal reproduced from a horizontal track of a recording medium, a video signal and a HiFi audio signal reproduced from an inclined track of the recording medium, and the video signal and the H signal.
An auto-tracking device for controlling a best tracking position based on an iFi audio signal, means for detecting a tracking best position of each envelope level of a video signal and a hifi audio signal, and a tracking limit point of an envelope level of a hifi audio signal. Detecting means; and counting adding means for adding a predetermined count to a tracking change amount in each envelope characteristic of the video signal and the HiFi audio signal based on a deviation amount between a best position of the video signal and a best position of the HiFi audio signal. The tracking position is controlled based on the count added by the counting adding means, and when the tracking position of the HiFi audio signal exceeds the limit point, the tracking position is controlled to the best position of the video signal and the HiFi audio signal is invalidated. And re-run from the side track An automatic tracking device characterized by switching to a generated audio signal.