JPH11328781A - Reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a reproducing device capable of performing SDL (long-time mode) reproducing by using only two SD (usual mode) heads without being affected by head bearing variance or mechanical variance. SOLUTION: This reproducing device is provided with an SD reproducing mode and an SDL reproducing mode for reproducing a signal at a tape speed of almost 1/2 of the SD reproducing mode. In this case, difference values (D-A) and (E-H) between a tracking error signal based on the reproducing signal with a CH0 head and a tracking error signal based on the reproducing signal with a CH2 head are obtained and tracking control is performed in the SDL reproducing mode based on these difference values.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a reproducing apparatus,
In particular, the present invention relates to a reproducing apparatus used in a digital video cassette recorder (DVCR) and capable of performing long-time mode reproduction with a normal mode head.

[0002]

2. Description of the Related Art In recent years, digital video cassette recorders (hereinafter, referred to as DVCRs) for consumer use have become widespread.
DVCRs have better image quality than conventional analog VTRs and can record for a long time. By the way, it is desired that the DVCR can be operated in the same manner as a conventional analog video cassette recorder. In particular, a normal mode (hereinafter referred to as SD) and one of the normal mode (SD) are used.
/ 2 long tape speed mode (SDL)
Must be able to be used in the same manner as in the case of an analog video cassette recorder.

A signal reproduced from a tape includes a tracking pilot signal called a so-called ATF pilot signal. This pilot signal has a plurality of frequencies F0, F1, F0, F2, F0,
Are repeatedly recorded on each track, such as F1, FO, F2. The reproducing circuit detects an ATF pilot signal from the reproduced signal, generates an ATF error signal corresponding to a tracking error signal from the detected ATF pilot signal, and controls the speed of a capstan motor to realize ATF servo tracking. .

[0006] FIG. 6 is an explanatory view showing a state of tracking by an SD head in a conventional DVCR, particularly a positional relationship between a head and a track. In a magnetic recording / reproducing apparatus adopting the azimuth system, it is general to use a head wider than the track width. ATF for tracking
The pilot signal is applied to each track (F0, F1, F0, F
It is written in the cycle of 2). As shown in FIG.
Looking at the scan of the channel 0 head that tracks a track having an ATF pilot signal of 0, the crosstalk of (A in which F2 on the left and F1 on the right) is generated and the cross of (F1 on the left and F2 on the right) There are two types of tracking, the case of C where talk is generated, and the ATF error signal obtained based on the magnitude relationship of the amount of crosstalk, and the polarity is alternately displayed.

FIG. 7 shows a head to be detected and an AT to be detected.
The relationship between the frequency of the F pilot signal, the ATF error, and the AD-converted data is schematically shown. As shown in FIG. 7A, reproduced data from a track is alternately captured by a channel 0 (hereinafter, represented by CH0) head and a channel 1 (hereinafter, represented by CH1) head. The ATF pilot signal of each track at that time is (F) as shown in FIG.
0, F1, F0, F2). Also, ATF
The error signal has a value as shown in FIG. In this case, the ATF errors actually used for the servo are the ATF errors of A and C generated from the head on the CH0 side, and the ATF errors of the B and D portions from the head on the CH1 side are not used. When the ATF error in the portions A and C is the center voltage, the device is in the center tracking state.

The ATF error is AD-converted and stored in an AD error register. Normally, the ATF error is shown in FIG.
As shown in (d), six samples are made in one track, and each sample value is stored in the AD error register. In practice, the difference between two consecutive ATF errors is used as a phase error and used for phase servo of the capstan motor.

[0008] FIG. 8 shows that the ATF servo is applied to CH0 and the SD head is used as in FIG.
FIG. 9 is an explanatory diagram showing the positional relationship between the head and the track when L is tracked. FIG. 9 shows an example of the detected head, the frequency of the detected pilot signal, the ATF error, and the AD.

According to the DVCR format, the tape speed in the SDL mode is one of the tape speed in the SD mode.
/ 2. Therefore, as shown in FIG. 8, when the tape recorded in the SDL mode is reproduced by the two SD heads, as shown in FIG. 8, when the data recorded in the SDL is reproduced by the SD head, the CH0 head tracks the just track, but the CH1 is tracked. The head tracks over tracks F0 and F1 or tracks F0 and F2. In this case, the ATF error on the CH0 side includes a center,
Error signals of the maximum value on the + side and the maximum value on the − side are output.

Since the conventional ATF servo is applied only on the CH0 side, the phase cannot be detected by SDL, and therefore, the ATF servo cannot be performed. Therefore,
As a result, SDL reproduction can be performed only when a dedicated SDL head is used.

If the SDL is to be reproduced by the SD head, it is necessary to perform a track shift because CH1 is not just tracked. However, even if the track shift method is used, since the shift amount needs to be fixed, the shift method depends on the pairing of two heads and the linearity of the mechanical deck, so that compatibility with other recording devices cannot be maintained. There is a problem.

[0011]

As described above, in the prior art, the reproduction was performed by changing the set of reproducing heads in the normal mode and the long time mode, which was uneconomical. When trying to play back SDL with an SD head, a track shift is necessary, but since the fixed shift amount depends on the pairing of the head and the linearity of the mechanical deck, there is no commonality and compatibility with other devices is lost. There was a problem.

The present invention solves this problem, and by a relatively simple method, it is possible to absorb variations in head pairing with only two SD heads and perform SDL reproduction without being affected by mechanical variations. It is an object of the present invention to realize a simple reproducing apparatus.

[0013]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides first and second heads for reproducing recorded data recorded on a magnetic recording medium, and the first and second heads. Switching means for switching between the first and second heads, a rotating drum on which the first and second heads are mounted, and a track from both adjacent tracks adjacent to a track on which a specific frequency signal recorded on a recording track on the magnetic recording medium is being reproduced. A first reproducing mode for reproducing at a first speed, and a second speed substantially half of the first speed, provided with a tracking means for obtaining a tracking error signal from the comparison of the reproduction crosstalk level and performing tracking control; And a second reproduction mode in which the reproduction signal is reproduced by the first head and the reproduction signal is reproduced by the second head. A tracking unit for performing tracking control based on a tracking error signal based on a playback signal from the first head in the first playback mode; In the second reproduction mode, tracking control is performed based on the difference value of the tracking error signal obtained by the difference calculation means.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a reproducing apparatus according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is an explanatory diagram showing a positional relationship between a head and a track in an ATF servo system according to an embodiment of the present invention. In this method, in order to perform SDL reproduction, ATF servo is applied so as to trace as shown in FIG. 1 using error signals from both the CH0 and CH1 heads. That is, tracking is performed at a position slightly shifted from the track as compared with the case of FIG. In this way, looking at the scan of the CH0 head, the crosstalk of A (I) and G where (F2 on the left and F1 on the right) is generated and the crosstalk of (F1 on the left and F2 on the right) are generated. There are two types of tracking, C and E, which are born.

In practice, since data is discarded every other time for processing, the polarity of the ATF error is alternately changed. That is, the phase is detected from the difference between the error at the point A of the CH0 head and the error at the point D of the CH1 head, or from the difference between the error at the point E of the CH0 head and the error at the point H of the CH1 head. The servo is applied based on this. However, since the polarities are exchanged, a value multiplied by 1 or -1 is passed to the phase servo.

As described above, since the error when the tracking position is totally shifted is reversed between the CH0 head and the CH1 head, the difference value increases and the phase servo amount tends to increase. For example, in FIG. 1, if the track position is shifted to the left in the figure, the error at the point A of the CH0 head changes in the + direction, and the error at the point D of the CH1 head changes in the-direction. -A) will double in the-direction. In addition, since the difference is used in this manner, the influence of head pairing variation and the effect of mechanical variation are offset, and such variation can be prevented from adversely affecting tracking, thereby improving device compatibility. .

FIG. 2 schematically shows the relationship between the head to be detected, the frequency of the detected ATF pilot signal, the ATF error, and the AD-converted data in this embodiment. As shown in FIG. 2A, the reproduced data from the track is alternately captured by the CH0 and CH1 heads, but only the data captured from one head is sufficient as the reproduced data. The ATF pilot signal of each track at that time is (F0, F0) as shown in FIG.
1, F0, F2). At this time, the ATF error signal has a value as shown in FIG.

The ATF error is alternately captured by the CH0 and CH1 heads, A / D converted, and stored in the A / D error register. As shown in FIG. 2D, the ATF error is sampled six times in one track, and each sample value is stored in the AD error register. However, the AD conversion data of the ATF error that is actually used is the data at the points A and E of the CH0 head, the points D and H of the CH1 head in every other time of the data captured by each head.

FIG. 3 is a flowchart showing a process from fetching ATF errors from CH0 head and CH1 head to reflection of the result. In step 100, ATF errors at points A and E of the CH0 head, and points D and H of the CH1 head are AD-converted and stored in the AD error register. Next, in step 101, the digital values of the six ATF errors are added and averaged, and the result is stored in a RAM or the like.

Next, at step 102, C
The average value of the error of the H0 head is calculated from the average value of the error of the CH1 head from the difference between the point D and the point A, the difference between the point H and the point E, that is, (DA) and (D−A). H-
The difference calculation of E) is performed. The result obtained in this manner is alternately multiplied by 1 or −1 in step 103 to determine the polarity, and the result Q is obtained.

FIG. 4 shows a capstan servo processing system using the polarity-determined result Q obtained in the processing shown in FIG. The result Q of the polarity discrimination is compared with the target voltage, and the difference is calculated by the subtracter 1 to be converted into a phase error signal, which is input to the capstan phase calculation processing 2. On the other hand, the capstan FG (Frequency Generator) period signal indicating the rotation speed from the capstan motor is compared with the target period, and the difference is obtained by the subtractor 3 to be converted into a speed error signal. Is entered. The output of the capstan phase calculation process 3 and the output of the capstan speed calculation process 4 are added by an adder 5 and input as a speed command control signal to a capstan driver that controls the driving of the capstan motor.

FIG. 5 is a block diagram showing a device configuration of a DVCR to which the present invention is applied. In FIG. 5, 11 is a channel encoder, 12 is an RF recording amplifier, 13 is a recording / reproduction switch and a head switch, 14 and 15 are CH0 and CH1 heads, 16
Is an RF reproduction amplifier, 17 is an equalizer, 18 is a PLL oscillator, 19 is an AD converter, 20 is a channel decoder,
1 is an ATF circuit, 22 is a microcomputer, 23 is a capstan driver, 24 is a capstan motor, and 25 is a magnetic recording tape.

Briefly explaining the function, the data to be recorded is encoded by a channel encoder 11, modulated and amplified into an RF signal by an RF recording amplifier 12, and passed through a recording / reproduction switch and a head switch 13 to two heads 14. And 15 are recorded on the magnetic recording tape 25. At the time of reproduction, the RF signals read by the two heads 14 and 15 pass through a recording / reproduction changeover switch and a head changeover switch 13 and an RF reproduction amplifier 16.
Amplified by An ATF pilot signal is extracted from the amplified RF signal by the ATF circuit 21 and processed.
The F error signal is input to the microcomputer 22.

The amplified RF signal is also input to the equalizer 17, and the output of the equalizer 17
Generates a synchronous clock, and the AD converter 19 performs AD conversion using the synchronous clock and outputs data. This data is decoded by the channel decoder 20 and the microcomputer 22
Is input and processed. The microcomputer 22 also receives a capstan FG cycle signal from the capstan motor 24, executes the arithmetic processing shown in FIG. 4, and inputs the speed command control signal to the capstan driver 23. The capstan driver 23 adjusts the coil drive signal of the capstan motor 24 based on this signal, and adjusts the tape transfer speed of the capstan motor 24 to perform final tracking servo.

[0025]

As described above, according to the first aspect of the present invention, first and second heads for reproducing recorded data recorded on a magnetic recording medium, and the first and second heads are provided. , A rotating drum on which the first and second heads are mounted, and reproduction crosstalk from both adjacent tracks adjacent to a track on which a specific frequency signal recorded on a recording track on the magnetic recording medium is being reproduced. A first reproducing mode for reproducing at a first speed; and a reproducing device for reproducing at a second speed substantially half of the first speed. And a tracking error signal based on a playback signal from the first head and a tracking error signal based on a playback signal from the second head. Comprises a difference calculation means for calculating a difference value between the first tracking means is in a first reproduction mode
In the second reproduction mode, the tracking control is performed based on the difference value of the tracking error signal obtained by the difference calculation means. As a result, it is possible to realize a reproducing apparatus capable of performing SDL reproduction using only two SD heads without being affected by variations in head pairing or mechanical variations.

According to a second aspect of the present invention, the difference value of the tracking error signal obtained by the difference calculating means is determined by comparing the tracking error signal by the reproduction signal at a certain point in time of the first head with the next tracking error signal by the first head. It is a difference value from a tracking error signal due to a reproduction signal of the second head following the reproduction signal.

Further, the invention of claim 3 of the present invention is characterized in that tracking control is performed in the second reproduction mode so as to maintain a predetermined off-track amount. As a result, the shift amount of the tracking is automatically canceled, the arithmetic processing becomes easy, and the SDL reproduction can be performed using only the two SD heads without being affected by the variation of the head pairing or the variation of the mechanism. A compatible playback device can be realized.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a positional relationship between a head and a track in an ATF servo system according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram schematically showing a relationship between a head to be detected by an ATF servo method, a frequency of a detected ATF pilot signal, an ATF error, and AD converted data in the embodiment of FIG. 1;

FIG. 3 shows an ATF from a head in the embodiment of FIG. 1;
9 is a flowchart showing processing until an error is captured and a result is reflected.

FIG. 4 is a diagram showing a processing system of a capstan servo using a result of the polarity discrimination obtained in the processing of FIG. 3;

FIG. 5 is a block diagram showing a device configuration of a DVCR to which the present invention is applied.

FIG. 6 is an explanatory diagram showing a positional relationship between a tracking head and a track in a conventional SD head.

FIG. 7 shows a head to be detected in the conventional ATF servo system, a frequency of the detected ATF pilot signal,
FIG. 4 is an explanatory diagram schematically showing a relationship between an F error and AD-converted data.

FIG. 8 is an explanatory diagram showing a positional relationship between a head and a track when an ATF servo is applied in CH0 and SDL is tracked by an SD head in the conventional method.

9 shows a head detected by the ATF servo method in the case of FIG. 8, a frequency of the detected ATF pilot signal, and A
FIG. 3 is an explanatory diagram schematically showing a relationship between a TF error and AD converted data.

[Explanation of symbols]

1, 3 ... subtractor, 2 ... capstan phase calculation processing, 4 ...
Capstan speed calculation processing, 5 ... Adder, 11 ... Channel encoder, 12 ... RF recording amplifier, 13 ... Recording / reproduction changeover switch and head changeover switch, 1
4, 15: Head, 16: RF reproduction amplifier, 17: Equalizer, 18: PLL oscillator, 19: AD converter, 20
... channel decoder, 21 ... ATF circuit, 22 ... microcomputer, 23 ... capstan driver, 24 ... capstan motor, 25 ... magnetic recording tape.

Claims (3)

[Claims] A first and a second head for reproducing recorded data recorded on a magnetic recording medium; a switching means for switching the first and the second head; and a first and a second head. A tracking error signal is obtained based on a comparison of a reproduction crosstalk level from a track on both sides adjacent to a track on which a specific frequency signal recorded on a recording track on the magnetic recording medium is being reproduced with a rotating drum mounted thereon, and tracking control is performed. A reproducing apparatus comprising a tracking means and having a first reproducing mode for reproducing at a first speed and a second reproducing mode for reproducing at a second speed substantially half of the first speed; A difference calculation for finding a difference value between a tracking error signal based on a reproduction signal from the first head and a tracking error signal based on a reproduction signal from the second head. A step, wherein the tracking means performs tracking control in the first reproduction mode based on a tracking error signal based on a reproduction signal from the first head, and the difference calculation means in the second reproduction mode A reproducing apparatus for performing tracking control based on a difference value of a tracking error signal to be obtained. 2. A difference value of a tracking error signal obtained by the difference calculating means is a tracking error signal by a reproduction signal at a certain point in time of the first head, and a difference value following a next reproduction signal by the first head. 2. The reproducing apparatus according to claim 1, wherein the difference value is a difference value from a tracking error signal generated by a reproduction signal from the second head. 3. The reproducing apparatus according to claim 1, wherein in the second reproduction mode, tracking control is performed so as to maintain a predetermined off-track amount.