JP3918229B2 - Tracking servo apparatus and method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention particularly relates to a tracking servo apparatus and method suitable for use in a magnetic recording / reproducing apparatus in which a digital audio signal is recorded / reproduced on a magnetic tape by a rotary head.
[0002]
[Prior art]
In a digital audio recording / reproducing apparatus (DAT) in which an audio signal is digitized and recorded / reproduced on a magnetic tape by two rotating heads having different azimuth angles, an ATF area is provided in a predetermined area of one track. The tracking control is performed using the ATF signal level obtained from the ATF area.
[0003]
That is, FIG. 13 shows a DAT track pattern. In DAT, digital audio data is recorded as an inclined track using an A channel head and a B channel head having different azimuth angles.
[0004]
As shown in FIG. 13, each track T1, T2, T3,... Is provided with a data area 100 for recording digital audio data, and ATF areas 101 and 102 are provided at both ends of the data area 100. Is provided.
[0005]
The ATF areas 101 and 102 are areas for performing ATF tracking control. In the ATF areas 101 and 102, four signals having frequencies f1, f2, f3, and f4 are recorded. The frequencies of the signals f1, f2, f3, and f4 are 130.67 kHz, 522.67 kHz, 784.00 kHz, and 1.568 MHz, respectively.
[0006]
Among these signals f1 to f4, the signal f1 is a tracking error detection ATF pilot signal, and the signals f2 and f3 are ATF sink signals for extracting the ATF pilot signal f1. The signal f4 is an erasing signal.
[0007]
The ATF sync signals f2 and f3 are frequencies that are not used in the 8-10 modulation and are set to frequencies that are not affected by the pilot signal f1. And, even between tracks having the same azimuth angle, two types of long and short patterns are alternately repeated, and a total of four types of patterns are recorded for every four tracks.
[0008]
Margins called IBG (Inter Block Gap) are arranged at both ends of each ATF area 101 and 102. This is intended to absorb signal position errors in overwriting or the like. In this IBG area, a 1.568 MHz signal (f4) is recorded in order to erase the previous recording.
[0009]
FIG. 14 shows an example of a conventional ATF control circuit for performing tracking control by detecting the ATF signal recorded in each track shown in FIG. In FIG. 14, the reproduction signal is supplied to the input terminal 110. The reproduction signal from the input terminal 110 is supplied to the low-pass filter 113 and the equalizer 111 through the reproduction amplifier 112. The low-pass filter 113 receives an ATF pilot signal (f ₁ ). The output of the low pass filter 113 is supplied to the envelope detection circuit 114. The envelope detection circuit 114 detects the reproduction level of the ATF pilot signal. The output of the envelope detection circuit 114 is supplied to the sample hold circuits 115A and 115B.
[0010]
On the other hand, the output of the reproduction amplifier 112 is waveform-shaped through the equalizer 111 and then supplied to the comparator 116. The comparator 116 converts this signal into a digital signal. An ATF sync signal is detected from the output of the comparator 116. The output of the comparator 116 is supplied to the controller 117. A switching pulse for head switching is supplied to the controller 117 from a terminal 118.
[0011]
In the controller 117, a sampling hold pulse for detecting the ATF pilot signal is formed. This sampling hold pulse is supplied to the sample hold circuits 115A and 115B.
[0012]
Outputs of the sample hold circuits 115A and 115B are supplied to the subtraction circuit 119. The subtraction circuit 119 compares the outputs of the sample and hold circuits 115A and 115B, and a tracking error signal is detected from the comparison output. This tracking error signal is output from the output terminal 120.
[0013]
As can be seen from the pattern of FIG. 13, if the level of the ATF pilot signal (f1) is examined at the start position of the ATF sync signals (f2, f3), the signal is always from the track on the right side in the head running direction, The signal from the adjacent track is detected at a timing delayed by 2 blocks.
[0014]
As described above, the controller 117 determines the crosstalk level of the ATF pilot signal from the right adjacent track and the crosstalk level of the ATF pilot signal from the left adjacent track based on the ATF sync signal detected by the comparator 116. A sampling hold pulse is generated so that and are held. The subtraction circuit 119 compares the crosstalk level of the ATF pilot signal from the right adjacent track with the crosstalk level of the ATF pilot signal from the left adjacent track, and forms a tracking error signal.
[0015]
As described above, in the DAT, using the reproduced ATF sync signal as a trigger, the levels of the ATF pilot signals of the right and left adjacent tracks are detected, and the levels of the ATF pilot signals of the right and left adjacent tracks are detected. In comparison, tracking control is performed.
[0016]
[Problems to be solved by the invention]
By the way, there is a case where a reproduction signal from a track of one channel cannot be obtained at the time of reproduction due to generation of a clog due to clogging of the head or the like. As described above, when a reproduction signal cannot be obtained from the track of one channel, the ATF servo is conventionally turned off to maintain the on-track. When a reproduction signal from one track cannot be obtained due to temporary clogging, a reproduction signal can be obtained after a while. When a reproduction signal can be obtained, the ATF servo is turned on again, and tracking servo by ATF is performed.
[0017]
As described above, when the reproduction signal from the track of one channel cannot be obtained, the method of turning off the ATF servo and maintaining the on-track is effective for the generation of the clog for a short time.
[0018]
However, there may be a case where a reproduction signal cannot be obtained from the track of one channel for a long time. Also, the clog may go off-track before it is restored. Further, there is a case where a head defect has already occurred during recording, and a recording track of one channel does not exist.
[0019]
As described above, when a reproduction signal from one track cannot be obtained, the method in which the ATF servo is turned off and the on-track method is maintained does not provide a reproduction signal from the track of one channel for a long time. This is difficult to deal with in cases such as when off-tracking occurs before the clog is recovered. Also, tracking control cannot be performed if a head failure has already occurred during recording.
[0020]
Accordingly, an object of the present invention is to provide a tracking servo apparatus and method capable of performing optimum tracking control in accordance with a case where a head failure occurs only during reproduction and a case where a head failure occurs during recording. Is to provide.
[0021]
[Means for Solving the Problems]
this The invention records a digital audio signal on a track by two rotary heads having different azimuth angles, and sets an ATF pilot signal and ATF pilot signal capture timing in an ATF area provided in a predetermined area of each track. In a tracking servo apparatus in which an ATF sync signal for recording is recorded and the crosstalk level of an ATF pilot signal from an adjacent track is compared to perform tracking control,
Depending on whether an ATF sync signal is detected during playback, Means for judging whether or not a reproduction failure has occurred in one of the two channels by two rotary heads having different azimuth angles;
By detecting the level of the gain setting signal for making the reproduction ATF pilot signal level constant, which is formed based on the AGC error signal obtained by the sum of the ATF pilot levels obtained from the adjacent tracks, Means for determining whether a defect has occurred during reproduction or a defect occurred during recording when reproduction failure has occurred in one of the two channels of two rotary heads having different azimuth angles;
A means for turning off the ATF servo loop if a defect occurs during recording, and a means for performing tracking control using an ATF pilot signal obtained from the track of the other channel where no defect occurs if a defect occurs during reproduction;
A tracking servo device characterized by comprising:
[0022]
In the present invention, a digital audio signal is recorded on a track by two rotary heads having different azimuth angles, and an ATF pilot signal and an ATF pilot signal capture timing are recorded in an ATF area provided in a predetermined area of each track. In a tracking servo method in which an ATF sync signal for setting is recorded, crosstalk levels of ATF pilot signals from adjacent tracks are compared, and tracking control is performed.
Depending on whether an ATF sync signal is detected during playback, Determining whether or not a reproduction failure has occurred in one of the two channels by two rotary heads having different azimuth angles;
By detecting the level of the gain setting signal for making the reproduction ATF pilot signal level constant, which is formed based on the AGC error signal obtained by the sum of the ATF pilot levels obtained from the adjacent tracks, A step of determining whether a defect has occurred in one of the two channels of the two rotary heads having different azimuth angles, a defect occurring during reproduction or a defect occurring during recording;
A step of turning off the ATF servo loop if a failure occurs during recording, and a step of performing tracking control using an ATF pilot signal obtained from the track of the other channel where no failure occurs if a failure occurs during playback;
A tracking servo method characterized by comprising:
[0024]
In the invention according to claim 1, it is determined whether or not reproduction failure has occurred in one of the two channels of the two rotary heads having different azimuth angles, and the two channels of the two rotary heads having different azimuth angles are determined. If a reproduction failure occurs in one of them, it is further determined whether the failure has occurred during reproduction or recording. If a defect occurs during recording, the ATF servo loop is turned off. If a defect occurs during reproduction, control is performed so as to perform tracking control using an ATF pilot signal obtained from the track of the other channel in which no defect has occurred. . As a result, even if a reproduction signal cannot be obtained from the track of one channel during reproduction, if a defect occurs during reproduction, the ATF pilot signal obtained from the track of the other channel can be used to maintain the on-track. .
[0025]
Also this In the invention, it is determined whether or not an error in the reproduction signal is equal to or less than a predetermined value, and in the case of a defect occurring during recording, it is determined whether or not the error in the reproduction signal is equal to or less than a predetermined value. If it is less than the predetermined value, the ATF servo loop is turned on. Thereby, even when a defect occurs during recording, the on-track can be maintained to some extent.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. The present invention is used, for example, in a DAT player in which a digital audio signal is recorded / reproduced on a magnetic tape by a rotary head. In the DAT player to which the present invention is applied, servo control is performed using a microcomputer as shown in FIG.
[0027]
That is, FIG. 1 shows a configuration during playback of a DAT player to which the present invention can be applied. In FIG. 1, 1 is a microcomputer, and 2 is a DSP (Digital Signal Processor) for digital audio signal processing. The microcomputer 1 and the DSP 2 are connected via a serial interface.
[0028]
Reference numeral 3 denotes a rotating drum. On the rotating drum 3, two rotating heads 4A and 4B having different azimuth angles are arranged. The magnetic tape 5 is wound around the rotating drum 3 at an angular interval of 90 degrees.
[0029]
These two rotations with different azimuth angles head With 4A and 4B, digital audio data is recorded on the magnetic tape 5 as an inclined track during recording. A data area for recording digital audio data is provided at the center of each track, and ATF areas are provided at both ends thereof. In this ATF area, an ATF pilot signal (frequency f1 signal) and an ATF sync signal (frequency f2 and f3 signals) for setting the timing for detecting the ATF pilot signal are recorded.
[0030]
A track formed by one azimuth angle head, for example, the rotary head 4A, is hereinafter referred to as an A channel track, and a track formed by the rotary head 4B is hereinafter referred to as a B channel track.
[0031]
The rotating drum 3 is rotated by a drum motor 6. A drive signal is given to the drum motor 6 from the microcomputer 1. A drum FG signal and a PG signal are generated according to the rotation of the rotary drum 3. The drum FG signal and PG signal are supplied to the microcomputer 1. The microcomputer 1 controls the rotation of the drum motor 6 based on the drum FG signal and the PG signal, and performs drum servo control.
[0032]
The magnetic tape 5 is transferred by a capstan motor 7. A drive signal is given from the microcomputer 1 to the capstan motor 7. In response to the rotation of the capstan motor 7, a capstan FG signal is generated. The capstan FG signal is supplied to the microcomputer 1. The microcomputer 1 controls the rotation of the capstan motor 7 based on the capstan FG signal.
[0033]
At the time of reproduction, the data of the A channel and the B channel recorded on the magnetic tape are reproduced by the rotary heads 4A and 4B. The reproduction signals from the rotary heads 4A and 4B are supplied to the RF amplifier 10. The RF amplifier 10 is supplied with a switching pulse from the microcomputer 1 and an AGC control signal. The outputs of the rotary heads 4A and 4B are switched by switching pulses from the microcomputer 1. The gain of the RF amplifier 10 is set by an AGC control signal from the microcomputer 1, and AGC control is performed so that the pilot signal level is constant.
[0034]
The output (RF DATA) of the RF amplifier 10 is supplied to the DSP 2 and also to the microcomputer 1. At the time of reproduction, the DSP 2 performs 8-10 conversion demodulation processing, error correction processing, etc., and decodes the digital audio signal.
[0035]
Further, an ATF pilot signal is extracted from the output of the RF amplifier 10, and this ATF pilot signal (ATF PILOT) is supplied to the microcomputer 1. At the same time, the output (RF DATA) of the RF amplifier 10 is supplied to the microcomputer 1, and the microcomputer 1 detects an ATF sync signal from the reproduction signal.
[0036]
Based on the ATF sync signal, the reproduction level of the ATF pilot signal is captured, and the tracking error signal is detected according to the detection level of the pilot signal from the adjacent track. This tracking error signal is added to the speed loop of the capstan servo. Thereby, tracking control is performed so that the rotary heads 4A and 4B become just tracks.
[0037]
Thus, the present invention is applied to a DAT player that performs tracking servo by ATF tracking control.
[0038]
In such a DAT player, clogging may occur due to head clogging or the like, and a reproduction signal from one of the rotary heads 4A and 4B may not be obtained. The DAT player to which the present invention is applied is configured so that the tracking servo can be appropriately performed even when the reproduction signal from the track of one channel cannot be obtained.
[0039]
The configuration of the servo system of the DAT player to which the present invention is applied will be described below with reference to the functional block diagram of the microcomputer 1.
[0040]
In FIG. 2, the reproduction signals from the rotary heads 4 </ b> A and 4 </ b> B are supplied to the RF amplifier 10. The output of the RF amplifier 10 is supplied to the DSP 2 and is also supplied to the ATF sink detection unit 11 of the microcomputer 1. The ATF sync detector 11 detects an ATF sync signal and forms a timing signal for taking in an ATF pilot signal in accordance with the ATF sync signal. This timing signal is generated according to the generation timing of the pilot signals of both adjacent tracks, and this timing signal is supplied to the A / D converter 12.
[0041]
Further, the component of the frequency f 1 of the ATF pilot signal is extracted from the output of the RF amplifier 10, and this signal is supplied to the A / D converter 12. The A / D converter 12 digitizes the level of the ATF pilot signal based on the timing signal based on the ATF sync signal from the ATF sync detection unit 11.
[0042]
That is, from the ATF area, the components of the ATF pilot signal are detected as shown in FIG. Of the components of this ATF pilot signal, the point P ₁ And P ₂ Is the level of the ATF pilot signal due to crosstalk from the adjacent track, and the point P _Three Is a component of the ATF pilot signal of the track. Based on the ATF sync signal from the ATF sync detector 11, the A / D converter 12 uses the point P ₁ ATF pilot signal component and point P ₂ Are extracted.
[0043]
The output of the A / D converter 12 is supplied to the ATF pilot level capturing unit 13. The ATF pilot level capturing unit 13 captures the crosstalk levels of pilot signals obtained from both adjacent tracks, subtracts them to calculate a tracking error, and adds them to calculate an AGC error.
[0044]
The output of the ATF pilot level capturing unit 13 is supplied to the head clog determining unit 14 and also supplied to the ATF pilot data processing unit 15. The ATF pilot data processing unit 15 calculates a tracking control amount based on the ATF tracking error obtained by the ATF pilot level capturing unit 13. The output of the ATF pilot data processing unit 15 is supplied to the ATF system control unit 16 and to the AGC control unit 17 for the ATF pilot signal.
[0045]
The head clog discriminating unit 14 determines whether or not an ATF sync signal is detected from the output of the ATF pilot level capturing circuit 13 and determines whether or not a reproduction signal of one channel cannot be obtained. The output of the head clog discrimination unit 14 is supplied to the ATF system control unit 16 and to the track presence / absence discrimination unit 18 and the switching pulse control unit 19. A mode setting signal indicating whether the mode is the SP mode or the LP mode is supplied from the terminal 27 to the switching pulse control unit 19.
[0046]
When one of the two heads 4A and 4B is clogged during recording, the recording track of one channel does not exist. In this way, the track presence / absence discriminating unit 18 detects a case where there is no recording track of one channel.
[0047]
The AGC pilot AGC control unit 17 forms control data for setting the gain of the RF amplifier 10 based on the AGC error. That is, since the level of the reproduced pilot signal varies depending on the state of recording current, head sensitivity, tape sensitivity, etc., the gain changes depending on the tape, and the control state of ATF tracking control changes. The AGC control of the ATF pilot signal is for avoiding such a change in the control state.
[0048]
The ATF pilot signal AGC control unit 17 forms a control signal for setting the gain of the RF amplifier 10 based on the AGC error signal obtained from the sum of the ATF pilot levels obtained from the adjacent tracks. This gain control signal is supplied to the RF amplifier 10, and AGC control is performed so that the reproduction pilot signal level is constant.
[0049]
The output of the track presence / absence discriminating unit 18 is supplied to the switch unit 20 and also to the switching pulse control circuit 19. The switching pulse control unit 19 determines whether or not the LP mode is selected when a reproduction signal from one of the channels is not obtained, and controls the switching pulse.
[0050]
During normal playback, the switch unit 20 is turned on. An ATF tracking error signal is obtained by subtracting the crosstalk level between adjacent reproduction pilot signals by the ATF pilot level capturing unit 13. The ATF pilot data processing unit 15 calculates a tracking control amount based on the ATF tracking error signal. The tracking control signal is supplied to the adding unit 21 via the ATF system control unit 16 and the switch unit 20.
[0051]
The addition unit 21 is supplied with a capstan control signal formed based on the capstan FG signal from the speed system control unit 22. The adder 21 adds the tracking control signal to the capstan control signal. The output of the adding unit 21 is supplied to the capstan motor 7 via the tape feed control unit 23 and the tape feed drive unit 24.
[0052]
Here, it is assumed that the reproduction output of the channel having one azimuth angle cannot be obtained due to clogging of the rotary head 4A or 4B. As a case where a single-channel playback signal cannot be obtained, there is a recording track, but a head failure occurs during playback, and a single-channel playback signal cannot be obtained. It is assumed that a recording track of one channel does not exist.
[0053]
If there is a recording track but a single-channel playback signal cannot be obtained, the head that has not caused the playback failure can detect the level of the pilot signal on both sides. Tracking tracking can be prevented by performing tracking control using the ATF pilot signal.
[0054]
Whether or not the reproduction signal of one channel is not obtained can be determined by whether or not the ATF sync signal can be detected from the adjacent tracks.
[0055]
That is, the ATF pilot level capturing unit 13 performs processing as shown in the flowchart of FIG.
[0056]
In FIG. 4, it is determined whether or not the pilot signal level has been captured (step ST1). The ATF pilot level data is captured by the hardware incorporated in the microcomputer 1 by starting the A / D converter 12 in each area at the timing set by the ATF sync signal. When the acquisition of the pilot signal level is completed, the acquired level is stored in the level data memory (step ST2). Then, an ATF tracking error and an AGC error are calculated using the captured pilot signal level (step ST3).
[0057]
It is determined whether or not such a pilot signal capturing process has been performed for the A channel (step ST4). If it is for the A channel, a flag indicating that there is an ATF sink for the A channel is set (step ST5). If not for the A channel, a flag indicating that there is an ATF sink for the B channel is set (step ST6).
[0058]
The head clog discriminating unit 14 performs processing as shown in FIG.
[0059]
In FIG. 5, it is determined whether or not the rotating drum 3 has made one rotation (step ST11). When the rotating drum 3 is rotated once, it is determined whether or not the ATF sync signal of the A channel is detected (step ST12).
[0060]
If the A channel ATF sync signal is not detected, it is further determined whether or not the A channel ATF sync signal is not detected several times continuously (step ST13), and the A channel ATF sync signal is detected. If the signal is not detected several times, the A channel reproduction failure flag is turned on, assuming that the A channel is reproduction failure (step ST14).
[0061]
When an ATF sync signal for channel A is detected in step ST12, the reproduction failure flag for channel A is turned off (step ST15). Then, it is determined whether or not a B channel ATF sync signal has been detected (step ST16).
[0062]
If the B channel ATF sync signal is not detected, it is further determined whether or not the B channel ATF sync signal is not detected several times continuously (step ST17). If the signal is not detected several times, the B channel reproduction failure flag is turned on, assuming that the B channel is reproduction failure (step ST18).
[0063]
If a B channel ATF sync signal is detected in step ST16, the B channel reproduction failure flag is turned off (step ST19), and the A channel sync flag and the B channel sync flag are turned off (step ST20).
[0064]
As described above, it is possible to determine a state in which a reproduction signal from one azimuth angle cannot be obtained. If the recording track exists correctly, but clogging or the like occurs during playback and a single-channel playback signal cannot be obtained, the head that has not caused the playback failure has a single-channel ATF control signal. Tracking control is performed using.
[0065]
By the way, at the time of reproduction in the DAT LP mode, the drum rotation speed is set to the standard rotation speed, the tape feed is set to 1/2 speed, and the same track is read twice and reproduced. In this case, as shown in FIG. 6, when the reproduction failure of the A channel occurs, the DSP 2 takes in the smaller reproduction RF data. Since this level is quite small, if there is any fluctuation, the error rate will deteriorate and the sound will be cut off.
[0066]
That is, when an A channel reproduction failure occurs in the LP mode, the reproduction RF data is as shown in FIG. 6C. This reproduction RF data is switched by a switching pulse as shown in FIG. 6A and is taken into the DSP 2. In the DSP 2, since the reference DREF (FIG. 6B) reads the low data first, and this becomes dominant, the error rate is very low, and even if the interpolation is performed, the sound is considerably bad. Then, an ATF pilot signal is obtained at a timing as shown in FIG. 6D, and a tracking error signal is output at a timing as shown in FIG. 6E by this ATF pilot signal.
[0067]
Therefore, as shown in FIG. 7, when an A channel reproduction failure occurs during LP reproduction, the switching pulse (FIG. 7A) is controlled to erase the RF data having a smaller reproduction level and only the larger RF data. I try to leave it.
[0068]
That is, FIG. 8 is a flowchart showing processing in the switching pulse control unit 19. In FIG. 8, it is determined whether or not channel A is defective in reproduction (step ST31). If the A channel is not defective in reproduction, the normal switching pulse is set (step ST32). If the A channel is poorly reproduced, it is determined whether or not the reproduction is in the LP mode (step ST33). If the reproduction is not in the LP mode, the normal switching pulse is set (step ST32). If the reproduction is in the LP mode, the switching pulse is set so as to erase the smaller signal (step ST34).
[0069]
The normal switching pulse has a timing as shown in FIG. 9A, and the switching pulse when the reproduction output of one channel cannot be obtained by the LP mode reproduction has a timing as shown in FIG. 9B.
[0070]
Furthermore, if the ATF servo is performed as it is, a pattern shift occurs and the data cannot be read. Therefore, the ATF servo point is shifted by using the fact that the bandwidth of the ATF servo during LP playback is as low as several Hz. So, good on-track is realized.
[0071]
If a head failure occurs during recording and there is no recording track of one channel, ATF tracking control is impossible, and the ATF tracking control is turned off to obtain a reproduction signal. . Whether or not a recording track exists can be detected from the AGC control level of the ATF pilot signal.
[0072]
That is, when one of the two heads 4A and 4B is clogged during recording, the recording track of one channel does not exist. Thus, when there is no recording track of one channel, ATF tracking control cannot be performed. Thus, the track presence / absence discriminating unit 18 detects a case where there is no recording track of one channel.
[0073]
Whether or not a recording track of one channel exists can be determined from the output of the AGC pilot AGC control circuit 17.
[0074]
That is, as described above, the AGC pilot AGC control unit 17 controls the gain of the RF amplifier 4 based on the AGC error signal obtained from the sum of the ATF pilot levels obtained from the adjacent tracks. Since the AGC error signal is obtained by the sum of the ATF pilot levels obtained from the adjacent tracks, the AGC error signal is small when the track of one channel is not recorded. For this reason, the gain setting signal from the AGC control unit 17 of the ATF pilot is increased, and the gain of the RF amplifier 10 is increased. From this, it can be determined whether or not there is a recording track of one channel, depending on whether or not the gain setting signal from the AGC control unit 17 of the ATF pilot has become a predetermined value or more.
[0075]
FIG. 10 is a flowchart showing the processing in the track presence / absence determining unit 18. In FIG. 10, it is determined whether or not the rotating drum 3 has made one rotation (step ST41). When the rotating drum 3 rotates once, it is determined from the output of the head clog discriminating unit 14 whether or not a reproduction failure has occurred in one of the channels (step ST42). If a reproduction failure has occurred in one of the channels, it is determined whether or not the gain setting signal from the AGC control unit 17 of the ATF pilot is greater than or equal to a predetermined value (step ST43). If the gain setting signal is equal to or greater than a predetermined value, the one-channel defect flag during recording is turned on (step ST44), and if the gain setting signal is equal to or smaller than the predetermined value, the one-channel defect flag during recording is turned off (step ST45).
[0076]
If a head failure occurs during recording and a recording track of one channel does not exist, a certain degree of improvement can be achieved by checking the number of errors and operating ATF control.
[0077]
That is, as shown in FIG. 11, the DSP 2 performs error correction processing on the reproduction data. In this error correction process, C1 syndrome is detected for each block. This C1 syndrome is supplied to the microcomputer 1 in the form of a flag that the data is OK. When the number of errors becomes equal to or greater than a predetermined value, the C1 syndrome becomes equal to or less than the predetermined value.
[0078]
As shown in the flowchart of FIG. 12, when it is determined that there is no track of one channel (step ST51), it is determined whether or not the C1 syndrome is equal to or greater than a predetermined value (step ST52). If the C1 syndrome is less than or equal to the predetermined value, ATF control is forcibly turned on (step ST53). If the C1 syndrome is greater than or equal to a predetermined value, ATF control is turned off (step ST54).
[0079]
As described above, in this example, whether or not a reproduction failure has occurred in one of the two channels of the two rotary heads 4A and 4B having different azimuth angles, and whether or not the ATF sync signal is detected. Judgment is performed. Then, by detecting the signal of the AGC loop for making the reproduction ATF pilot signal level constant, it is determined whether the defect has occurred during reproduction or has occurred during recording.
[0080]
If there is a reproduction failure in one of the two channels of the two rotary heads 4A and 4B, it is further determined whether the failure has occurred during reproduction or recording. When the ATF servo loop is turned off and a defect occurs during reproduction, control is performed so that tracking control is performed using an ATF pilot signal obtained from the track of the other channel in which no defect has occurred.
[0081]
As a result, even if a reproduction signal cannot be obtained from the track of one channel during reproduction, if a defect occurs during reproduction, the ATF pilot signal obtained from the track of the other channel can be used to maintain the on-track. .
[0082]
In addition, when a reproduction failure of one channel occurs in the LP mode, the switching pulse is controlled so that the RF data with a lower reproduction level is erased and only the larger RF data is left. As a result, the error rate is improved when a reproduction failure of one channel occurs in the LP mode.
[0083]
Further, in the case of a defect occurring during recording, it is determined whether or not an error in the reproduction signal is equal to or less than a predetermined value. If the error in the reproduction signal is equal to or less than a predetermined value, the ATF servo loop is turned on. Thereby, even when a defect occurs during recording, the on-track can be maintained to some extent.
[0084]
【The invention's effect】
According to the present invention, when a reproduction failure has occurred in one of the two channels of two rotary heads having different azimuth angles, it is further determined whether the failure has occurred during reproduction or recording. If a defect occurs during recording, the ATF servo loop is turned off. If a defect occurs during reproduction, control is performed so that tracking control is performed using an ATF pilot signal obtained from the track of the other channel where no defect has occurred. As a result, even if a reproduction signal cannot be obtained from the track of one channel during reproduction, if a defect occurs during reproduction, the ATF pilot signal obtained from the track of the other channel can be used to maintain the on-track. .
[0085]
Further, it is determined whether or not an error in the reproduction signal is equal to or less than a predetermined value. If a defect occurs during recording, it is determined whether or not the error in the reproduction signal is equal to or less than a predetermined value. If it is less than the value, the ATF servo loop is turned on. Thereby, even when a defect occurs during recording, the on-track can be maintained to some extent.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an example of the configuration of a DAT to which the present invention can be applied.
FIG. 2 is a functional block diagram showing an example of a DAT servo configuration to which the present invention can be applied.
FIG. 3 is a schematic diagram used for explaining the configuration of an example of a DAT servo system to which the present invention can be applied;
FIG. 4 is a flowchart used for explaining an example of the configuration of a DAT servo system to which the present invention can be applied;
FIG. 5 is a flowchart used for explaining an example of the configuration of a DAT servo system to which the present invention can be applied;
FIG. 6 is a timing chart used to explain an example of the configuration of a DAT servo system to which the present invention can be applied.
FIG. 7 is a timing chart used for explaining an example of the configuration of a DAT servo system to which the present invention can be applied.
FIG. 8 is a flowchart used for explaining an example of the configuration of a DAT servo system to which the present invention can be applied;
FIG. 9 is a timing chart used to explain an example of the configuration of a DAT servo system to which the present invention can be applied;
FIG. 10 is a flowchart used to describe an example of the configuration of a DAT servo system to which the present invention can be applied.
FIG. 11 is a block diagram showing another example of a DAT configuration to which the present invention can be applied.
FIG. 12 is a block diagram showing another example of a DAT configuration to which the present invention can be applied.
FIG. 13 is a schematic diagram used to explain a DAT track pattern;
FIG. 14 is a block diagram used for explaining a conventional ATF servo circuit.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Microcomputer, 2 ... DSP, 4A and 4B ... Rotary head, 7 ... Capstan motor, 13 ... ATF pilot level taking-in part, 14 ... Head clog discrimination | determination part, 15 ... ATF pilot data processing unit, 18 ... track presence / absence discrimination unit, 19 ... switching pulse control unit,

Claims (4)

In order to record a digital audio signal on a track by two rotary heads having different azimuth angles, and to set an ATF pilot signal and the timing for capturing the ATF pilot signal in an ATF area provided in a predetermined area of each track. In the tracking servo apparatus in which the ATF sync signal is recorded, the crosstalk level of the ATF pilot signal from the adjacent track is compared, and tracking control is performed,
Means for determining whether or not a reproduction failure has occurred in one of the two channels of the two rotary heads having different azimuth angles, depending on whether or not the ATF sync signal is detected during reproduction;
By detecting the level of the gain setting signal for making the reproduction ATF pilot signal level constant based on the AGC error signal obtained by the sum of the ATF pilot levels obtained from the adjacent tracks, the azimuth angle Means for determining whether a defect has occurred during reproduction or a defect during recording when reproduction failure has occurred in one of the two channels of two rotating heads of different from each other;
If a defect occurs during recording, the ATF servo loop is turned off. If a defect occurs during playback, the ATF pilot signal obtained from the track of the other channel in which no defect has occurred is used to perform tracking control. A tracking servo device characterized by that.   Further, it is determined whether or not an error in the reproduction signal is equal to or less than a predetermined value in the case of a defect occurring during the recording, and the ATF servo loop is turned on if the error in the reproduction signal is equal to or less than a predetermined value. Item 10. The tracking servo device according to Item 1. In order to record a digital audio signal on a track by two rotary heads having different azimuth angles, and to set an ATF pilot signal and the timing for capturing the ATF pilot signal in an ATF area provided in a predetermined area of each track. In the tracking servo method in which the ATF sync signal is recorded, the crosstalk level of the ATF pilot signal from the adjacent track is compared, and tracking control is performed.
Determining whether or not a reproduction failure has occurred in one of the two channels of the two rotary heads having different azimuth angles depending on whether or not the ATF sync signal is detected during reproduction;
By detecting the level of the gain setting signal for making the reproduction ATF pilot signal level constant based on the AGC error signal obtained by the sum of the ATF pilot levels obtained from the adjacent tracks, the azimuth angle If a reproduction failure has occurred in one of the two channels of the two rotating heads having different from each other, a step of determining whether the failure has occurred during reproduction or has occurred during recording;
If the defect occurs during recording, the ATF servo loop is turned off. If the defect occurs during playback, the tracking control is performed using the ATF pilot signal obtained from the track of the other channel where no defect occurs. A tracking servo method characterized by that.   Further, it is determined whether or not an error in the reproduction signal is equal to or less than a predetermined value in the case of a defect occurring during the recording, and the ATF servo loop is turned on if the error in the reproduction signal is equal to or less than a predetermined value. 6. The tracking servo method according to item 5.

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