JP2574526B2 - Magnetic recording / reproducing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-density magnetic recording / reproducing apparatus for magnetically recording and reproducing images and sounds, and more particularly, to improving the quality of a reproduced signal.

[Prior Art] FIG. 9 is a block diagram showing a configuration of a conventional VTR automatic tracking control device disclosed in, for example, Japanese Patent Application Laid-Open No. 64-39655.

In the figure, a magnetic tape (1) on which a video signal (2) and a control signal (3) are recorded is a capstan (14) (hereinafter referred to as CP) driven by a capstan motor (9) (hereinafter referred to as CP motor). By the arrow (1
Sent in the direction of 5). Control signal (3) is CP (1
The data is read by the control head (5) in association with the driving of (4). The video signal (2) is read by the rotating video heads (4a), (4b). The rotating video heads (4a) and (4b) are mounted on a rotating drum (6) and rotated by a drum motor (8) driven by a drum motor drive circuit (7). The rotating drum (6) is further provided with a magnet piece (18) and a rotating transformer (21), and a fixed detection head (19) is provided below.
Is provided.

Further, frequency generators (10) and (10a) (hereinafter referred to as FG) are provided for the CP motor (9) driven and controlled by the CP motor drive control circuit (11) and the drum motor (8). . Incidentally, (19) is a control amplifier.

The reference signal generation circuit (12) is a 3.58 MHz oscillator (12a)
(Hereinafter referred to as 3.58 MHz OSC), a down counter phase correction circuit (12b), down counters (12c) and (12b), and a drum servo control circuit (13) includes a drum phase comparison circuit (13a) Frequency comparison circuit (13b) and drum flip-flop signal generation circuit (13c)
F circuit) and a mixing filter circuit (13d).

The CP servo control circuit (17) includes a CP phase comparison circuit (17a), a CP frequency comparison circuit (17b), and a mixing filter circuit (17c).

The output of the drum FF circuit (13c) is input to a video head amplifier circuit (25) and a Hi-Fi audio head amplifier circuit (26) via a delay circuit (23), and a drum phase comparison circuit (13a) From the microcomputer (3) via a delay circuit (20) and a 1/2 frequency-divided vertical reference signal (22).
3) is given.

The outputs of the video head amplifier circuit (25) and the Hi-Fi audio amplifier circuit (26) are output from the video signal envelope detection circuit (27), the Hi-Fi audio envelope detection circuit (28), and the A / D converter (29), respectively. ) And (30), microcomputer (33) via memory circuits (31) and (32)
Has been entered.

Next, the principle of the Hi-Fi VTR of the VHS system for performing the deep / surface recording will be described with reference to FIGS. 14 (a) and 14 (b).

As shown in FIG. 14 (a), a video head (4a),
The (4b) and the Hi-Fi audio heads (24a) and (24b) are attached to the rotary drum (6) at an accurate index of 180 degrees. In addition, video head (4a),
The level difference between the drum side of (4b) and the Hi-Fi audio heads (24a) and (24b) is maintained at a constant value (for example, 16 μ) as shown in FIG. 15 (b). At the time of recording, first, as shown in FIG. 14 (b), a Hi-Fi having a gap g ₀ (a large gap width of about 0.8 μ) in the tape advancing direction (15).
Apply a large recording current to the audio head (24)
Hi-Fi audio signals are recorded up to the deep portion of the magnetic body (1b) formed on the 16μ film base (1a) to a thickness of about 4μ. Next, a recording current is passed through a video head (4) having a gap g ₁ (a gap width as small as about 0.3 μ),
A video signal is recorded on a surface layer located closer to the surface than the deep layer where the Hi-Fi audio signal is recorded.

FIG. 15 (a) shows this state when viewed from the tape magnetic surface. The tape recorded in this way is
When reproducing (self-recording / reproducing) with the same VTR as R, the positional relationship of the head becomes the same in recording and reproduction as shown in FIG. 15 (b). Therefore, as shown in FIG. 15 (c), the tracking position at which the envelope l _{v of the} video signal is maximum,
A tracking position the envelope l _a of -Fi audio signal is maximum, is both t ₀ becomes coincident.

On the other hand, as shown in FIG. 16, when the positional relationship between the recorded head and the reproduced head is different (for example, when the recording and reproducing VTRs are different), the envelope l _v
A tracking position t ₁ but having the maximum tracking position t ₂ the envelope l _A of Hi-Fi audio signal is maximum
Then, a deviation occurs.

Next, the operation of the conventional apparatus in the case of FIG. 16 will be described with reference to FIG.

FIG. 10 shows signal waveforms of respective parts in the conventional device.

First, a down counter (12) that counts down the FG signal (for example, 720 Hz) of the drum frequency generator (10a) attached to the drum motor (8) and the 3.5 MHz reference oscillation signal.
The output signal of c) is compared with the drum frequency comparison circuit (13b). A drum PG pulse signal (30 Hz) is input to the drum FF circuit (13c). This drum PG
The pulse signal is generated by a magnet piece (18) attached to the rotating drum (6), and is detected by a drum phase detecting head (19) similarly attached to the rotating drum (6). This drum PG pulse signal is a signal indicating the rotational phase of the head. The signal output from the drum FF circuit (13c) is, for example, a signal having a waveform as shown in FIG. 10 (A). Fig. 10 (A)
Is input to the drum phase comparison circuit (13a). Drum phase comparison circuit (1
3a) is a video head switch signal and FIG. 10 (B)
Is compared with a signal having the waveform shown in FIG. The signal shown in FIG. 10 (B) is the output signal of the down counter phase correction circuit (12b). This signal is the 3.58MHz OSC (1
It is generated by the down counter phase correction circuit (12b) from the 3.58MHz reference oscillation signal output from 2a). That is, the down counter phase correction circuit (12b)
Count down the reference oscillation signal, correct the phase, and output the signal. Both output signals of the drum frequency comparison circuit (13b) and the drum phase comparison circuit (13a) are smoothed and mixed by the mixing filter circuit (13d). The mixed signal is applied to a drum motor drive circuit (7). As a result, the speed and phase are controlled, and a stable rotation operation at 1800 rpm is performed.

On the other hand, a capstan frequency generator (hereinafter referred to as “CP-FG”) attached to the capstan motor (9) (1)
FG signal (for example, 720Hz) output from 0) and 3.58MHz
The signal obtained by counting down the reference oscillation signal by the down counter (12d) is compared in the CP frequency comparison circuit (17b).

The control signal is detected by the control head (5) and amplified by the control amplifier circuit (16). The amplified control signal (shown in FIG. 10 (G)) is compared with a tracking control signal (shown in FIG. 10 (E)) created by the microcomputer (33) in the CP phase comparison circuit (17a).

Both output signals of the CP frequency comparison circuit (17b) and the CP phase comparison circuit (17a) are smoothed and mixed by a mixing filter circuit (17c) and applied to a capstan motor drive circuit (11).
As a result, the speed and phase are controlled, and the magnetic tape (1) is driven at a stable tape speed.

On the other hand, a rotary video head switch signal, which is an output signal of the drum flip-flop circuit (13c), is applied to a video head amplifier circuit (25), and the video head (4a), The input from (4b) is switched. The head switch signal for the rotating video head is supplied to a delay circuit (23)
And is delayed by a predetermined amount. This delay amount is a delay amount corresponding to the mounting position of the Hi-Fi audio heads (24a) and (24b) with respect to the video heads (4a) and (4b). By performing this delay, a Hi-Fi audio head switch signal having a waveform as shown in FIG. 10 (C) is generated. This signal is Hi-
The signal is supplied to a Fi audio signal head amplifier, and the input is switched from one of the Hi-Fi audio heads (24a) and (24b) according to this signal.

The video signal and the Hi-Fi audio signal amplified by the two head amplifiers (25) and (26) in this way are switched according to their respective head phases, so that a continuous envelope signal is extracted. Become.

Next, the FM video signal amplified by the video head amplifier (25) is detected by a video signal envelope detection circuit (27), and the detected analog envelope detection signal is A / A
The signal is converted into a digital signal by the D conversion circuit (29) and stored in the memory circuit (31). Similarly, the FM audio signal amplified by the Hi-Fi audio head amplifier (26)
The analog envelope detection signal detected and detected by the audio signal envelope detection circuit (28) is converted into a digital signal by the A / D conversion circuit (30), and the memory circuit (3
It is stored in 2). These A / D conversion circuits (29), (30)
Can be processed at 8 bits (256 stages) at a sampling frequency of 10 kHz, and can be constructed relatively inexpensively.

The contents of the memory circuits (31) and (32) are supplied to the microcomputer (33) and added. Further, the microcomputer (33) includes a 1/2 frequency-divided vertical signal generation circuit (22)
With reference to the 1/2 frequency-divided vertical reference signal (30 kHz) having the waveform shown in FIG.
A tracking control signal having the waveform shown in FIG. This signal is applied to the CP phase comparison circuit (17a), and the control pulse signal (10th waveform) shown in FIG.
The phase is compared with that in FIG. Also, FIG. 10 (F)
Shows a signal waveform in the CP phase comparison circuit (17a).

Next, the operation of the microcomputer (33) will be described with reference to the flowchart of FIG.
This will be described in detail with reference to the drawings.

The microcomputer (33) has a memory circuit (3
Envelope digital values related to both the video signal and the Hi-Fi audio signal are input from 1) and (32), and these are added. By microcomputer (33)
This addition value, that is, the level of the synthetic envelope (hereinafter, referred to as
The following arithmetic processing is performed on the “synthetic envelope value” l).

First, the start point and l ₀ and the combined envelope value is also l _0. The l ₀ value subtraction value p which appropriately determined and subtracted from, compared with the criterion value J ₀ is set first. Where J ₀
Is selected as (J ₀ <l ₀ ), so that J ₀ <l ₀ −p.

Then the discrimination value j ₀ and j ₀ = l ₀ -p, by controlling the tracking amount in the negative direction seeking synthetic envelope value l _1, compares the discrimination value j ₀ and l ₁ -p. If the result is l ₁ -p <j ₀ = l ₀ -p, a similar comparison is made sequentially for the synthesized envelope values l ₂ and l ₃ . This result is 3 when step co discriminant value j ₀ smaller than its discrimination value j ₀ is stored in the RAM of the temporary micro the computer (33) as _{l 2 -p <j 0 l 3} -p <j 0 .

Then combining the envelope value l point as a determination value j ₀ stored l _a is obtained. That is, even if the tracking amount is searched in the negative direction, it is determined that the combined envelope value 1 does not take the maximum value, and a point where l ₀ = j ₀ = l ₀ −p is obtained. The tracking amount at this time is stored as a point A in the RAM in the microcomputer (33).

Next, the tracking amount is controlled in the forward direction from point A (returned in the reverse direction). In addition, synthetic envelope value l ₂ is determined again and compared with l ₂ -p as determined value j _2. Results
If j ₂ = l ₂ −p, the tracking amount is further searched in the positive direction, and the combined envelope value l ₁ is obtained.
Further operation of comparing the determined value j ₂ are sequentially repeated as follows.

l ₁ -p> j ₂ = l ₂ -pl ₀ -p> j ₁ = l ₁ -pl ₁₁ -p> j ₀ = l ₀ -pl ₁₂ -p> j ₁₁ = l ₁₁ -p:: : L ₁₅ -p> j ₁₄ = l ₁₄ -p::: l ₁₉ -p> j ₁₈ = l ₁₈ -p After such repetition, when the synthetic envelope 1 reaches l _{20 at} which it begins to decrease, the comparison result Becomes l ₂₀ −p ≦ j ₁₉ = l ₁₉ −p.

Thus, l _i -p value as set discrimination value j _i and the result of the comparison of whether the former is larger than the latter, the equivalent time search comparison operation is repeated, the setting discrimination value j _i when becomes smaller It is stored in the RAM in the temporary microcomputer (33) (j ₁₉ is stored in this example). Next, the tracking amount is further searched in the positive direction, and the synthesized envelope value l _i is j.
₁₉ and made a point l _b is required. That _{l b = j 19 = j 18} ... j 14 become points is obtained, tracking the amount of time this is B
The points are stored in the RAM in the microcomputer (33).

By the above operation, tracking points A and B are obtained,
That is, it is temporarily stored in the RAM. Next, the intermediate point between the points A and B is set as the final best tracking point, the search is performed again in the negative direction from the point B, and the tracking search is stopped and fixed at the point C.

The tracking control signal shown in FIG. 10 (E) is generated by the tracking control signal generator in the microcomputer (33) based on the point C. This signal is applied to the CP phase comparison circuit (17a).

Although the above-described operation is always performed operation at the start a reproduction operation, in which the repeated when it is less than determination value j ₁ also during playback is synthesized envelope value l _1.

FIG. 13 is a diagram showing the tracking characteristics in this embodiment. FIG. 13 (a) shows the envelope value l _v of the video signal.
FIG. 13B is a characteristic diagram of the envelope value l _a of the Hi-Fi audio signal with respect to the tracking amount, and FIG. 13B is a characteristic diagram of the combined envelope value l with respect to the tracking amount. The tracking amount t _{3 at} which the combined envelope value l becomes the maximum value. In this case, good tracking control is achieved for both the video signal and the Hi-Fi audio signal.

[Problems to be Solved by the Invention] A tracking control method of a conventional magnetic recording / reproducing apparatus is as follows.
With the above configuration, both the video signal and the audio signal could not be driven to the optimum track position, and the S / N value of the demodulated signal could not be sufficiently secured. In particular, when the relationship between the position of the recording head and the position of the reproducing head is significantly different, use may not be possible.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a magnetic recording / reproducing apparatus capable of performing optimal track position control and obtaining a signal having a good S / N value.

Means for Solving the Problems In order to achieve such an object, a first aspect of the present invention is to reproduce a video signal recorded on a magnetic tape and move the video signal in response to a transition control signal. A rotating video head including a movable head, a video envelope detection circuit for detecting a reproduced video signal by amplitude detection and generating a video envelope signal, a capstan motor for running a magnetic tape, and a constant value shift control signal for the movable head. Means for supplying and fixing the movable head, and variably controlling the traveling amount of the magnetic tape by controlling the capstan motor; and detecting the moving amount of the magnetic tape in the video track width direction when the movable head is fixed from the traveling amount of the magnetic tape. Means for determining the amount of movement of the head; means for calculating the amount of track bending based on the determined amount of movement and the video envelope signal; Means for generating a shift control signal in accordance with the amount of bending of the track and supplying the signal to the movable head.

According to a second aspect of the present invention, in addition to the first aspect, the apparatus further comprises means for controlling the capstan motor so that the video envelope signal when the movable head is fixed at the tracking control position after the tracking search is maximized. And

[Operation] In claim (1) of the present invention, a video signal reproduced by the rotating video head is amplitude-detected by a video envelope detection circuit to generate a video envelope signal.

On the other hand, the movable head is controlled to be fixed when calculating the bending amount of the track. Further, at this time, the capstan motor is run, and the running amount is variably controlled. The moving amount of the movable head in the video track width direction is obtained from the running amount at this time, and the track bending amount is calculated based on the obtained moving amount and the video envelope signal.

Then, a transition control signal is generated in accordance with the calculated track bending amount. This transition control signal is supplied to the movable head. The movable head moves according to the transition control signal,
As a result, the rotating video head follows the track according to the calculated track bending amount.

Further, in claim (2), the capstan motor is further controlled so that the video envelope signal becomes maximum at the tracking control position after the tracking search, and the track following is performed according to the calculated track bending amount and the tracking position. Will be

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a reference example. In FIG. 1, (1) to (32) have the same functions as those of the components of the conventional example shown in FIG. (34) is a piezoelectric movable element, (35) is a slip ring, (36a), (36
b) is a microcomputer.

FIG. 2 is a diagram showing a head scanning method of the video head in the present reference example. In FIG. 2, (37) shows a track pattern of a video signal. FIG. 3 is a view showing a mounted state of the video head (4) in the present reference example.
FIG. 4 (a) is a diagram showing the relationship between the tracking position by the capstan servo and the envelope voltage of the Hi-Fi audio signal, and FIG. 4 (b) is the relationship between the displacement of the piezoelectric element and the envelope voltage of the video signal. FIG. In the drawings, the same reference numerals denote the same parts.

 Hereinafter, the operation of the reference example will be described in detail.

First, the drum FG attached to the drum motor (8)
The drum frequency comparison circuit (13b) compares the FG signal of (10a) with the output signal of the down counter (12c) that counts down the 3.58 MHz reference oscillation signal. The drum PG pulse signal is input to the drum FF circuit (13c), and its output signal is compared with the output signal of the down counter phase correction circuit (12b) by the drum phase comparison circuit (13a). Both output signals of the drum frequency comparison circuit (13b) and the drum phase comparison circuit (13a) are smoothed and mixed by a mixing filter circuit (13d), and the signals are applied to a drum motor drive circuit (7). In this way, a stable rotation operation in which the speed and the phase are controlled is performed.

On the other hand, the FG signal of CP-FG (10) and the down counter (12
The output signal of d) is compared by the CP frequency comparison circuit (17b). On the other hand, the control signal detected by the control head (5) and amplified by the control signal amplifier circuit (16) is compared with the tracking control signal generated by the microcomputer (36a) in the CP phase comparison circuit (17a). Is done. Both output signals of the CP frequency comparison circuit (17b) and the CP phase comparison circuit (17a) are output from the mixing filter circuit (1
The mixture is smoothed and mixed in 7c) and added to the capstan motor drive circuit (11). In this way, the magnetic tape (1) is driven at a stable tape speed whose speed and phase are controlled.

The output signal of the drum FF circuit (13c) is applied to the video head amplifier circuit (25) as a head switch signal for the rotating video head, and the input from the video heads (4a) and (4b) is switched. The FF signal delayed by the delay circuit (23) is applied to a Hi-Fi audio head amplifier circuit (25), and the Hi-Fi audio head (24a),
The input from (24b) is switched. In this manner, the video signal and the Hi-Fi audio signal which are respectively amplified by the head amplifiers (25) and (26) are switched according to the phase of each head, and a continuous envelope signal is extracted. (The signal waveforms of the respective blocks and their relationships are the same as in FIG. 10 described in the conventional example.) Next, the FM audio signal amplified by the Hi-Fi audio head amplifier (25) is a Hi-Fi audio signal. The detected analog envelope signal is detected by an envelope detection circuit (27), converted into a digital signal by an A / D conversion circuit (29), and stored in a memory circuit (31). The voltage value of the memory circuit (31) is applied to the microcomputer (36a). Further, the microcomputer (36a) generates a tracking control signal based on the 1 / 2-divided vertical reference signal generated by the 分 -divided vertical signal generation circuit (22), and this signal is used as a CP phase comparison circuit ( 17a), and the phase is compared with the control pulse signal.

Next, the operation of the microcomputer (36a) is the same as the operation of the microcomputer (33) described in the conventional example when the envelope detection signal of the video signal is zero. It can be read as the Fi envelope value. Hi-Fi
The relationship between the audio envelope signal and the tracking control amount is as shown in FIG. That is, in the range between the point A and the point B, the envelope voltage value becomes maximum at the point C, and tracking is performed at this position.
The CP servo is controlled. As a result, the Hi-Fi audio head becomes the best tracking and the Hi-Fi audio signal is
The S / N value is the best.

Next, tracking of the video head will be described.

As shown in FIG. 3, the movable element (34) to which the transition control signal is applied moves the video head (4) in the track width direction according to the applied voltage. As a result, as shown in FIG. 2, the video head (4) scans positions such as O, P, and Q with respect to the video track (37). At this time, in the reproduction output from the video head (4), as shown in FIG. 4 (b), the envelope voltage value changes in accordance with the position of the video head (4). The displacement width of the movable element is set at the points M and N, and the envelope voltage value of the video signal when the position of the video head is changed between them is converted into a digital signal by the A / D conversion circuit (30), and the memory circuit Stored in (32). The content of the memory circuit (32) is a microcomputer (36b)
Supplied to Furthermore, the microcomputer (36b)
The video heads (4a) and (4b) determine the position q point at which the maximum envelope voltage value can be obtained for each of the video heads (4a) and (4b) based on the 1/2 frequency-divided vertical reference signal created by the 1/2 frequency-divided vertical signal generation circuit (22). (The displacement control at the time of calculation is the same as the method of searching for the tracking amount of the microcomputer (33) described in the conventional example, and the synthesized envelope value is read as the video envelope value and the tracking amount is read as the displacement amount.) A shift control signal corresponding to the position is generated, and the control signal is applied to the movable element (34) via the slip ring (35). The movable element (34) provides the video heads (4a) and (4b) with a displacement in the track width direction at which the maximum envelope value is obtained in response to the control signal.

As a result of such control, a video head (4a) can be used for any tape recorded with any VTR (tape in which the positional relationship between a recorded video track and a Hi-Fi audio track is different, that is, a tape recorded by another person). ), (4b), Hi
-The optimum tracking position is set for each of the Fi audio heads (24a) and (24b), and the best S / N value can be obtained for both the video signal and the Hi-Fi audio signal.

The above-described operation is always performed when the reproduction operation is started, but may be performed even during reproduction when each envelope value becomes equal to or smaller than a certain discrimination value.

In the above reference example, a digital servo circuit is used for the drum servo system and the capstan servo system, but an analog servo circuit may be widely used.

In addition, the position where the envelope is maximum is set as the tracking point, but it goes without saying that an arbitrary point can be selected by setting the threshold.

Further, when the Hi-Fi audio signal is not recorded, it can be easily realized by fixing the tracking control by the capstan servo at a preset position and moving the video head in the track width direction for tracking.

In addition, although the piezoelectric element has been described as the movable element, it is needless to say that any other movable element such as a moving coil such as an electrostrictive element or a voice coil may be used.

 FIG. 5 shows an embodiment according to the present invention.

Hereinafter, the operation of the embodiment shown in FIG. 5 will be described in detail.

First, the drum FG attached to the drum motor (8)
The drum frequency comparison circuit (13b) compares the FG signal of (10a) with the output signal of the down counter (12c) that counts down the 3.58 MHz reference oscillation signal. The drum PG pulse signal is input to the drum FF circuit (13c), and its output signal is compared with the output signal of the down counter phase correction circuit (12b) by the drum phase comparison circuit (13a). The drum frequency comparison circuit (13b) and the drum phase comparison circuit (13
The two output signals a) are smoothed and mixed by the mixing filter circuit (13c), and applied to the drum motor driving circuit (7). As a result, a stable rotation operation in which the speed and the phase are controlled is performed.

On the other hand, the FG signal of CP-FG (10) and the down counter (12
The output signal of d) is compared by the CP frequency comparison circuit (17b). On the other hand, the control signal amplified by the control signal amplifier circuit (16) and the tracking control signal created by the microcomputer (42) are compared by the CP phase comparison circuit (17a). This CP frequency comparison circuit (17b)
Both output signals of the CP phase comparison circuit (17a) are smoothed and mixed by a mixing filter circuit (17c) and applied to a capstan motor drive circuit (11), and the magnetic tape (17) is controlled at a stable tape speed with controlled speed and phase. 1) is driven. The output signal of the drum FF circuit (13c) is applied to the head amplifier circuit (38) as a head switch signal for the rotary head,
The input from the rotary heads (4a) and (4b) is switched. In this way, the signal amplified by the head amplifier (38) is switched according to the phase of each head,
A continuous envelope signal is extracted.

Next, the signal amplified by the head amplifier (38) is detected by an envelope detection circuit (39), and the detected analog envelope signal is converted into a digital signal by an A / D conversion circuit (40), and is converted into a digital signal by a memory circuit (41). ) Is stored. The contents of the memory circuit (41) are input to the microcomputer (42). Further, the microcomputer (42) creates a tracking control signal based on the 1 / 2-divided vertical reference signal created by the 分 -divided vertical signal generation circuit (22), and uses this signal as a CP phase comparator ( Compare the phase with the control pulse signal in addition to 13a).

The tracking servo using the capstan is performed in this manner. In this embodiment, the amount of bending of the track pattern (37) shown in FIG. 6 is used (FIG. 8) using the operation of the capstan servo. Perform a track scan for measurement.

At this time, first, the input signal (transition control signal) of the movable element (34) is set to zero or a fixed potential, and the movable element (34)
Is fixed in a fixed position. Next, according to a signal generated by the track control unit (45) of the microcomputer (42),
The tracking amount is sequentially searched in both positive and negative directions by the capstan servo control circuit (17). As a result of this search, when the envelope value of the reproduced signals (46), (47), and (48) shown in FIG. 7 is the maximum value or within a certain range from the maximum value, the optimum tracking position is determined. The bend amount of the track pattern (37) is obtained from the tracking amount at this time by the container (43) and stored.
Then, the tracking position at which the average envelope value of one track is maximum is calculated and stored. Next, tracking control is performed by the capstan servo control circuit (17) so as to be at the tracking position, and the value obtained by correcting the offset amount for the tracking position with respect to the bending amount of the track pattern (37) is used as the normal track pattern. It is stored as the bending amount of (37).

Based on the amount of bending of the track pattern (37) obtained and stored in this way, the shift controller (44) corrects the amount of bending of the track pattern (37) (voltage transition control signal) by using the slip ring (35). Is applied to the movable elements (34) and (34).

Thus, the track trajectory of the reproducing head can be made to coincide with the track trajectory of recording, and the best tracking can be performed.

Next, the microcomputer (4
The operation 2) will be described.

The microcomputer (42) has a memory circuit (41)
, An envelope digital signal is input, and the microcomputer (42) performs the following arithmetic processing on the envelope level l.

First, let's set the start point to l ₀ and the envelope value
Let l be ₀ . The l ₀ value appropriately determined was subtracted value P is subtracted from, compared with the determination value J ₀ is set first. Here, J ₀ is selected as (J ₀ l ₀ ), so that J ₀ <l ₀ −P. Then the discrimination value J ₀ and J ₀ = l ₀ -P, obtains an envelope value l ₁ by controlling the tracking amount in the negative direction, comparing the determined value j ₀ and l ₁ -P. If the result is l ₁ -P <j ₀ = l ₀ -P, a similar comparison is sequentially performed on the envelope values l ₂ and l ₃ . The result is _{l 2 -P <j 0 l 3} -P < If the determination value j ₀ is smaller than as J ₀ is stored in RAM in that discrimination value j ₀ temporary microcomputer (42).

Next, the point at which the envelope value l becomes the stored discrimination value j ₀
Find l _a . That is, even if the tracking amount is searched in the negative direction, it is determined that there is no maximum value of the envelope value l,
The point where l ₀ = j ₀ = l ₀ −P is obtained, and the tracking amount at this time is set as point A in the microcomputer (42).
Temporarily store in RAM.

Then it controls the tracking amount in the forward direction from point A (back in the reverse direction), compares again asked l ₂ -P envelope value l ₂ as determined value j _2. If the result is j ₂ = l ₂ −P, the tracking amount is further searched in the positive direction, and the envelope value l ₁
The calculated, Yuku sequentially repeating the operation to compare determined values j _2.

l ₁ -P> j ₂ = l ₂ -P l ₀ -P> j ₁ = l ₁ -P l ₁₁ -P> j ₀ = l ₀ -P l ₁₂ -P> j ₁₁ = l ₁₁ -P:: : L ₁₅ -P> j ₁₄ = l ₁₄ -P::: l ₁₉ -P> j ₁₈ = l ₁₈ -P In this way, the synthetic envelope 1 starts to decrease.
When l ₂₀ is reached, the comparison result is l ₂₀ −P ≦ j ₁₉ = l ₁₉ −P.

In this way, the tracking amount is sequentially searched in the positive direction,
Predetermined subtraction P from synthetic envelope value l _{1 at} each check point
Is compared with the set discriminant value j ₁ set by the composite envelope value before the value of l ₁ −P, and if it is larger or equal, the search comparison operation is repeated. ₁ is temporarily stored in the RAM in the microcomputer (42) (in this example, i ₁₉ is stored). Then further searching the tracking amount in the positive direction, obtaining a l _b that envelope value l ₁ is the j _19. That is, l _b = j ₁₉ = j ₁₈ … j ₁₄
Is obtained, and the tracking amount at this time is temporarily stored as a point B in the RAM in the microcomputer (42).

The point C which gives the maximum envelope value between these points A and B is obtained, and the RAM in the microcomputer (42) is obtained.
(See FIG. 12). Up to this point, the method of calculating the maximum envelope value of a certain point in the track has been described. If the tracking amount that gives the maximum envelope value in the head scanning direction of the track is continuously calculated, it is the track bending amount. Becomes Further, an average value of the envelope value at each tape position in the head scanning direction of the track (may be processed by an integration circuit) is obtained, and tracking control is performed on the tape position at which the average value becomes the maximum. A correction value process of subtraction or addition is performed as an offset amount by the tape position from the track bending amount to obtain a normal bending amount. At this time, the sampling interval (the point at which the maximum envelope value is obtained) may be roughened, and the microcomputer (42) may calculate the amount of track bending by calculating the interval and smoothly connecting the intervals.
Further, the track bend amount of each point may be obtained by one tape scan, or the track bend amount may be obtained by performing a tape scan for each point.

The tape position tracking control may be performed at a position near the center of one track where the envelope value is maximum. In this case, the deterioration of the S / N ratio near the center of the reproduction screen of a television or the like is minimized until the track bend follows, and the time of image quality deterioration at the center of the screen watched by the viewer can be reduced.

Needless to say, the operation of reading and correcting the track bending amount may be performed only at the start of reproduction or when the running mode changes. If the envelope value becomes lower than a certain discrimination value during reproduction, the above operation may be repeated.

Further, in the above embodiment, both the drum servo system and the capstan servo system are shown in a circuit configuration generally called a digital servo circuit. However, the present invention is not limited to this, and it goes without saying that analog servo circuits may be widely used. No.

Although the piezoelectric element is shown as the movable element, any other movable element such as an electrostrictive element or a voice coil may be used.

Also, the operation was described for one head,
Needless to say, this may be performed for each head, so that the steps of the recording tracks corresponding to the heads (4a) and (4b) can be absorbed.

As described above, in the case of this embodiment, the rotary transformer (21)
The playback signals of the rotating video heads (4a) and (4b) input to the head amplifier (38) through the head amplifier (38)
And is input to the envelope detection circuit (39).
The output envelope voltage value is converted into a digital signal in the A / D converter (40) and stored in the memory circuit (41).

The contents of the memory circuit (41) are
The arithmetic unit (43) is input to the arithmetic unit (43), which calculates the tracking position where the audio envelope value is maximum and the rotating video head position where the video envelope value is maximum. ) Is stored in RAM (not shown). The calculated value is stored and held in the RAM until an envelope voltage value equal to or less than a certain value is input. If the envelope voltage is below a certain value, RA
The calculated value stored in M is updated, and the displacement control unit (44) and the tracking control unit (45) operate according to the updated value, and the tracking position and rotating video head (4a),
The position in the width direction (4b) is also updated, and is reproduced with the optimum S / N value according to the information recorded on the magnetic tape (1).

That is, according to this embodiment, based on the playback envelope value input to the head amplifier (38), the audio S /
By controlling the capstan servo control circuit related to the N value and the movable element (34) supporting the rotating video heads (4a) and (4b), both the audio S / N value and the video S / N value are optimized. To control.

In addition, the calculated value from which the maximum envelope value of audio and video is obtained is stored in the RAM which is the storage means of the microcomputer (42), and is held until the envelope voltage value becomes equal to or less than a certain value. There is no fluctuation due to extraneous electromagnetic waves or power surges, and a stable tracking control method is provided.

[Effects of the Invention] As described above, according to the first aspect of the present invention, the rotating video head is made to follow the track by the calculated track bending amount, so that the reproduction trajectory of the rotating video head is recorded. Even if it deviates from the trajectory, it can be recovered and the video signal can be reproduced without deteriorating the S / N.

According to the second aspect of the present invention, the rotating video head is made to follow the track by the tracking position in addition to the calculated track bending amount, so that the period of image quality deterioration during reproduction is further reduced. become.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram of a magnetic recording / reproducing apparatus according to this reference example, FIG.
The figure is a longitudinal sectional view showing the attached state of the video head.
4A is a characteristic diagram of an audio envelope value-tracking control amount, FIG. 4B is a characteristic diagram of a video envelope value-variable element displacement amount, and FIG. 5 is a block diagram of a magnetic recording / reproducing apparatus according to an embodiment of the present invention. FIG. 6, FIG. 6 is an explanatory diagram of a track pattern, FIG. 7 is a reproduction output pattern diagram of a rotary head, FIG. 8 is an explanatory diagram of a track bending amount, FIG. 9 is a block circuit diagram of a conventional device, and FIG. Fig. 9 is a signal waveform diagram of each part, Fig. 11 is a flowchart showing the operation of the microcomputer of the conventional device, Fig. 12 is an explanatory diagram of the operation of the microcomputer of the conventional device, Fig. 13 is a tracking characteristic diagram of the conventional device, 14 (a) and 14 (b) are illustrations of the deep surface recording method, and FIG. 15 is self-recording / reproducing (no bending)
FIG. 16 is an explanatory diagram showing the relationship between the recording pattern of the deep surface recording magnetic tape and its reproduction envelope signal in the case of (1). FIG. 16 shows the recording pattern of the deep surface recording magnetic tape in the case of another self-recording (with bending) and its reproduction. FIG. 4 is an explanatory diagram illustrating a relationship with an envelope signal. In the figure, (1) is a magnetic tape, (2) is a video signal, (3) is a control signal, (4) is a rotating video head, (5) is a control head, (6) is a rotating drum, and (7) is Drum motor drive circuit, (8) drum motor, (9) capstan motor, (10) frequency generator, (11) CP motor drive circuit, (12) reference signal generation circuit, (13) Drum servo control circuit, (14) capstan, (16) control amplifier, (17) CP servo control circuit, (18) magnet piece, (19) detection head, (20) delay circuit, (20) 21) is a rotary transformer, (2
2) is a 1/2 frequency-divided vertical signal generation circuit, (23) is a delay circuit,
(24) is an audio head, (25) is a video signal head amplifier, (26) is an audio signal head amplifier, (27)
Is a video signal envelope detector, (28) is a Hi-Fi audio envelope detector, (29) and (30) are A / D
Conversion circuit, (31) and (32) are memory circuits, (33) is a microcomputer, (34) is a piezoelectric movable element, (35) is a slip ring, (36) is a microcomputer, (37)
Is a track pattern, (38) is a head amplifier, (39) is an envelope detection circuit, (40) is an A / D conversion circuit, (41)
Is a memory circuit, (42) is a microcomputer, (43)
Is an arithmetic unit, (44) is deformation control, (45) is a tracking control unit, and (46), (47), and (48) are reproduction signals. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (2)

(57) [Claims] A video signal recorded on a magnetic tape is reproduced, a rotating video head including a movable head movable in response to a transition control signal, and a reproduced video signal is amplitude-detected to generate a video envelope signal. A video envelope detection circuit, a capstan motor that runs the magnetic tape, and a fixed value shift control signal supplied to the movable head to fix the movable head and control the capstan motor to vary the travel distance of the magnetic tape Means for controlling, a means for obtaining the moving amount of the head in the video track width direction when the movable head is fixed from the moving amount of the magnetic tape which is movably controlled, and a track bending amount based on the obtained moving amount and the video envelope signal. And a shift control signal generated in accordance with the calculated track bending amount and supplied to the movable head. Magnetic recording and reproducing apparatus and a stage. 2. A magnetic recording / reproducing apparatus according to claim 1, further comprising means for controlling a capstan motor so that a video envelope signal when the movable head is fixed at the tracking control position after the tracking search is maximized. Playback device.