JPH09251683A - Reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a stable constant tracking servo with high accuracy by detecting the rotational error information of a rotary drum and generating a servo control signal based on a corrected tracking detection period. SOLUTION: A servo circuit 30 obtains rotation error information by detecting the speed of revolution of a rotary head drum 50 and by comparing the result with a reference speed of revolution. Then, the circuit 30 monitors reference phase position timings of the drum 50 detectable from switching pulses and timing detection pulses TTP to be supplied from a timing detection pulse generating circuit 27 and measurement is implemented for the period as a tracking detection period. The circuit 30 obtains tracking error information by comparing the measured value with the reference value for the tracking detection period and generates a capstan servo signal Scp based on the tracking error information. Then, a tracking servo is performed by increasing or decreasing the rotation speed of a capstan 28.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tape reproducing apparatus for scanning an inclined track by a helical scan method,
In particular, the present invention relates to a reproducing device that performs tracking servo by controlling the relative speed between the running speed of a tape-shaped recording medium and the rotating speed of a rotating drum.

[0002]

2. Description of the Related Art For example, a digital audio tape player (DAT recorder / player) for recording and reproducing digital audio data on a magnetic tape, or a DAT system also using a magnetic tape is used as a data storage system for a computer. , Digital data storage devices (DDS devices) have been developed for recording and reproducing computer data.

In these devices, for example, 90
High density is achieved by running the tape with the magnetic tape wound at a wrap angle of 0 °, rotating the rotating drum, and performing recording / reproduction scanning by the helical scan method using the magnetic head on the rotating drum. It is possible to record.

In this case, inclined tracks TK _A and TK _B are formed on the tape as shown in FIG. The inclined tracks TK _A and TK _B are tracks formed by a pair of heads (A head and B head) mounted on a rotating drum and having different azimuth directions, and are tracks having opposite azimuths.

By the way, at the time of reproduction, the magnetic head must accurately trace the track TK on the tape. As a tracking control method, for example, D
In the DS reproducing device, a tracking servo control operation called a so-called timing ATF method is performed. The timing ATF method measures the time (tracking detection period) from the reference phase position of the rotating drum until the head detects a predetermined signal (timing detection signal) from the track, and compares the measured value with the reference value. Then, the error is used as servo error information.

Then, the servo error information is used to control the rotational speed of the capstan motor for running the tape so that it is reflected in the tape running speed. That is, the tape running speed is adjusted to adjust the relative speed between the drum rotation speed and the tape running speed so that a good tracking state can be obtained.

For example, when the scanning position of the magnetic head with respect to a certain track is in a position corresponding to the line (timing) shown as TR _{A in the} figure as shown in FIG. 9, the phase position of the rotary drum is the reference position. Suppose that At the time when the reference phase position is reached during rotation of the drum, for example, a pulse signal is generated from a pulse generator (PG) arranged in the drum motor, so that the rotating drum becomes the reference phase position. Timing TR _A can be detected. After that, the magnetic head contacts the magnetic tape,
As the track TK _{A is} scanned, a timing detection signal is detected as reproduction data at a predetermined position P _TTP on the track. This timing detection signal is
It is assumed that a pulse is obtained at a position P _TTP that is predetermined based on the detection of the synchronizing signal and the address in the data.

In the figure, the track T is
Although three types of scanning with different tracking phase states with respect to K _A are shown, the period (tracking detection period) from the timing of the reference phase position of the rotating drum (position of line TR _A ) to the timing of reaching position P _TTP is: ,
, The scanning times are different as indicated by t1, t2 and t3.

As the tracking detection period, the time t1 obtained when the magnetic head is in a good tracking state with respect to the track TK, that is, in the state of tracing the center of the track TK _A as described above is used as a reference value in advance. Therefore, when the scanning is performed during tracking servo control and the time t1 is measured as the tracking detection period, the measured value and the reference value match. That is, in this case, there is no error between the measured value and the reference value, and a good tracking state is obtained. On the other hand, when scanning is performed in the tracking phase state such as or, the measurement value in the tracking detection period becomes t2 or t3, and there is an error compared with the reference value. In this case, it means that there is a tracking deviation corresponding to the error, and by reflecting this in the tape running speed, it is possible to execute the servo control toward the just tracking state.

To execute such timing ATF servo, a reference value must be obtained in advance. As described above, this reference value is based on the timing of the reference phase position of the rotary drum in the just tracking state. It is a time value until the timing when the timing detection signal is obtained. Since the timing detection signal is generated, for example, based on the detection of the synchronization signal at a predetermined address on the track, its position P _TTP is fixed on each track of various tapes. It is unavoidable that a positional deviation occurs due to a mechanical error in the playback device. For this reason, when reproducing certain file data in the DDS reproducing device, the reference value of the tape (the file data track thereof) must be measured before reading the reproduction data.

To measure the reference value, scanning is performed on the track in various tracking phase states, an average value is calculated from the tracking detection period measured in each scanning, and this is used as the reference value. Processing is performed. For example, the image is shown in FIG. As shown in the drawing, for example, TJ1 to TJ for the track TK _A
When scanning is performed in a plurality of different tracking phase states as shown in FIG. 5, and an average value is calculated from each tracking detection period measured during those scanning, a tracking phase state near the tracking phase state TJ3 in the figure is obtained. The tracking detection period can be obtained. This can be considered as the tracking detection period in the just tracking state, and thus this should be set as the reference value.

[0012]

By the way, in order to realize such timing ATF with high accuracy, it is necessary that the rotational speed of the rotary drum is accurately maintained constant.
That is, if there is rotation unevenness or the like in the rotation operation of the rotating drum, an error component due to rotation unevenness is added to the measurement value during the tracking detection period, and the tracking operation becomes unstable. However, in practice, it is extremely difficult to completely eliminate the rotation unevenness of the rotary drum, and it is inevitable that the tracking operation becomes unstable to some extent due to this rotation unevenness.

[0013]

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to eliminate a measurement error in a tracking detection period due to uneven rotation of a rotating drum and realize a highly accurate and stable tracking servo. And

For this reason, a drum rotation error detecting means, a tracking detection period measuring means, and a servo control signal generating means are provided as a servo control system as a reproducing apparatus configured to perform tracking servo by a so-called timing ATF method. . The drum rotation error detection means detects rotation error information of the rotating drum in a period from a certain time point when the rotating drum is near the reference phase position to when the head reaches the vicinity of the predetermined position on the track. The tracking detection period measuring means measures the tracking detection period from the time when the rotary drum reaches the reference phase position to the time when the head reaches a predetermined position on the track and a timing detection signal is obtained. Then, the servo control signal generation means corrects the tracking detection period measured by the tracking detection period measuring means with the rotation error information detected by the drum rotation error detection means, and then the corrected tracking detection period is set as a reference value. And generate a servo control signal. In other words, after removing the error due to uneven rotation from the measurement value during the tracking detection period,
The measured value of the tracking detection period is compared with the reference value of the tracking detection period to generate the servo control signal.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a reproducing apparatus of the present invention will be described below. In this example, the DDS recording / reproducing apparatus is used.
Three systems, DS2 and DDS3, have been developed.
The DDS reproducing apparatus of this example is a DD that employs a format that enables higher density recording than DDS / DDS2.
It corresponds to S3. It should be noted that the present invention includes DDS
It can be applied to a system adopting ATF tracking other than the reproducing apparatus. The description will be made in the following order. 1. DDS3 system track format 2. Configuration of recording / reproducing apparatus 3. 3. Configuration and operation for timing ATF 4. Example of tracking servo operation that eliminates the influence of rotational error

1. Track Format of DDS3 Method The track format of DDS3 method will be described with reference to FIGS. FIG. 6 shows a track of the helical scan system formed on the magnetic tape 90.

Each track is formed as a track having a track width TW by so-called azimuth solid recording by a recording head (not shown). Adjacent tracks are regarded as reverse azimuth tracks. That is, the tracks TK _A in one azimuth direction and the tracks TK _B in the other azimuth direction are alternately formed. During reproduction, the reproducing head 16 scans the track. Although the head width HW of the reproducing head 16 is set wider than the track width TW, crosstalk from adjacent tracks is prevented by the so-called azimuth effect.

In the DDS format, a pair of adjacent tracks TK _A and TK _B are called 1 frame and 2
Two frames are a unit called one group. And an ECC frame is provided behind the group. An amble frame is provided after the ECC frame.
However, the number of frames of this amble frame is not specified and may not be provided. ECC frames and amble frames will define the boundaries of the groups on the tape 90. In each group, index information for partitioning a series of data is added to the last frame in the group.

The data format in one track is shown in FIG. As shown in FIG. 7A, margin areas are formed at both ends of one track, and the area sandwiched between the margin areas is the main data area. The main data area is divided into fragments of 96 units to which fragment addresses 0 to 95 are given. One fragment consists of 133 bytes, and its contents are shown in FIG. 7 (b).
It is shown in (c).

Each fragment of 78 units whose fragment addresses are 9 to 86 is as shown in FIG. 7B.
A sync signal area of 1 byte is provided at the beginning, and a sync signal in a predetermined pulse form is recorded. A 6-byte address and subcode area are provided following the sync signal area. A fragment address is recorded in 1 byte, and a subcode is recorded in 5 bytes.

Next, 2 bytes are used as a header parity area, and the following 112 bytes are used as a data area. Actual data is recorded in this data area. The last 12 bytes of the fragment are used as the ECC area. A so-called C1 correction code is recorded in this ECC area.
The C1 correction code is an error correction code for the data in the fragment, that is, the correction process is completed in fragment units.

Fragment addresses 0-8 and 87-
Each fragment of 18 units up to 95 is shown in Fig. 7 (c).
7, a sync signal area, an address and subcode area, a header parity area, and an ECC area are provided as in the fragment of FIG. 7B. However, FIG.
In the fragment of (b), it was used as a data area 11
The 2 bytes are used as an ECC area and a C2 correction code is recorded. The C2 correction code is a code of a correction series that is completed within one track.

A C3 correction code is further added as a correction code. This will be recorded in the ECC frame shown in FIG. This C3 correction code is a code of a correction series that is completed within one group. Also, C1
By confirming the error status by the correction code and the C3 correction code, it is possible to confirm in which part the error has occurred in one track. However, the C2 correction code is recorded by being interleaved in one track, so that C2 correction code is recorded. The error occurrence position within one track cannot be confirmed from the error situation due to the correction code.

2. Configuration of Recording / Reproducing Apparatus FIG. 1 shows the configuration of the recording / reproducing apparatus of this example. The interface unit 1 is a unit that is connected to an external host computer (not shown) to exchange data. At the time of recording, the data from the host computer is received and supplied to the index adding circuit 2 and the sub code generator 8. At the time of reproduction, the operation of outputting the data reproduced from the magnetic tape 90 to the host computer is performed.

At the time of recording, the index adding circuit 2
Performs a process of adding index information to the input data for each group described above. The data to which the index information is added is the C3 encoder 3,
Error correction codes of C3 series, C2 series, and C1 series are added in the C2 encoder 4 and the C1 encoder 5, respectively. Each of the C3 encoder 3, the C2 encoder 4, and the C1 encoder 5 temporarily stores data in the memory 6 for each data unit forming one group and performs processing. Then, the C3 encoder 3 generates an error correction code C3 for the data string corresponding to the track width direction and adds it as the data of the last ECC frame of the data of one group. Further, the C2 encoder 4 generates the error correction code C2 of the data string corresponding to the track direction, and
0-8 fragments and 87-9 as shown in (c)
The error correction code C2 within 5 fragments is used. Further, the C1 encoder 5 generates an error correction code C1 in fragment units.

The data to which the error correction codes C1, C2 and C3 are added is supplied to the sub code adding circuit 7. The subcode generation unit 8 generates various subcode data and fragment addresses based on the data supplied from the interface unit 1 and supplies them to the subcode addition circuit 7. The generated sub-codes include, for example, separate counter information indicating a data delimiter, record counter information indicating the number of records, an area ID indicating each area defined on the tape format, a frame number, and a group count indicating the number of recording units. Information, checksum, etc.,
These are generated together with the fragment address in the subcode generating section 8.

The subcode adding circuit 7 adds these subcodes and fragment addresses for each data unit corresponding to one fragment. That is, the information recorded in the address / subcode area in FIGS. 7B and 7C is added.

Subsequently, in the header parity adding circuit 9, the CRC code recorded in the header parity area in FIGS. 7B and 7C is added. This CRC code is a 2-byte parity code for error detection for the subcode and fragment address.

Subsequently, in the 8/10 modulation circuit 10, a so-called 8/10 modulation process is performed in which the input data is converted from 8 bits into 10 bits in 1-byte units. At 11, a sync signal is added. The sync signal is the sync signal of the first 1 byte of the fragment shown in FIGS. 7B and 7C.

Further, in the margin adding circuit 12, FIG.
As shown in (a), data corresponding to margin areas at both ends of the track is added, and at this stage, a recording data string conforming to the track format of FIG. 7 is generated. The recording data thus generated is supplied to the recording amplifier 13.

The signal amplified by the recording amplifier 13 is supplied to the recording head 15 in the rotary head drum HD via the rotary transformer 14, and the magnetic recording operation is performed on the magnetic tape 90 running by the recording head 15. The magnetic tape 90 is housed in a tape cassette 91, and the magnetic tape 90 is pulled out from the tape cassette 91 (recording / reproducing) and wound (loaded) around the rotary head drum 50. And capstan 2
The magnetic tape 90 is run at a constant speed by rotating the capstan 28 at a constant speed while being sandwiched by the pinch roller 29 and the pinch roller 29.

FIG. 2 shows an image of operation during recording and reproduction. The magnetic tape 90 pulled out from the tape cassette 91 is tilted in the height direction with respect to the rotary head drum 50 by the guide pins 51, 52, and 53, and the magnetic tape 90 is about nine.
While being wound in the section of 0 °, the capstan 28 and the pinch roller 29 travel at a constant speed. The rotary head drum 50 is rotated while slidingly contacting the magnetic tape 90, so that the recording operation by the recording head 15 forms a recording track by the helical scan method on the magnetic tape 90 as shown in FIG. Go.

Although only one recording head 15 and one reproducing head 16 are shown in FIG. 1, since the azimuth solid recording method is actually used, the azimuth angles are different as shown in FIG. Two recording heads 15
A, 15B, two reproducing heads with different azimuth angles 1
6A and 16B are arranged on the peripheral surface of the rotary drum in a state of being separated from each other by 180 °. At the time of recording, the recording heads 15A and 15B alternately come into sliding contact with the magnetic tape 90, so that tracks TK _A and TK _B having different azimuth angles are alternately formed as shown in FIG.

During reproduction, as shown in FIG. 2, the magnetic tape 90 wound around the rotary head drum 50 is run and the rotary head drum 50 is rotated, so that the reproducing heads 16A and 16B alternately record tracks. The trace is continued and the recorded data is read out.

Then, as shown in FIG. 1, the reproducing head 16 (1
The signals read by 6A and 16B) are supplied to the reproduction amplifier 18 via the rotary transformer 17. Although only one rotary transformer 14 for recording and one rotary transformer 18 for reproduction are actually shown, the rotary transformer 14 is not shown in FIG.
The rotary transformer 18 is provided corresponding to A and 15B, and the rotary transformer 18 is also provided corresponding to the reproducing heads 16A and 16B.

The signal amplified by the reproduction amplifier 18 is supplied to the sync signal detection circuit 19 and the sync signal is detected. Then, a reproduction clock synchronized with the synchronization signal detected by the internal PLL circuit is generated, and a signal (RF signal) amplified by the reproduction amplifier 18 by the reproduction clock.
Is binarized.

The 10-8 demodulator 20 performs a decoding operation for the 8-10 modulation at the time of recording on the binarized data and restores it to 8-bit unit data. The reproduced data demodulated into 8-bit unit data is subjected to a parity check of the subcode and the fragment address by the header parity check circuit 21 using the 2-byte header parity shown in FIGS. 7B and 7C. The data for which the parity check has been completed is supplied to the subcode separation circuit 22 and the timing detection pulse generation circuit 27.

The subcode separation circuit 22 extracts the fragment address and subcode data and supplies them to the system controller 31. The actual data other than the fragment address and the subcode data is sent to the C1 decoder 23, C2 decoder 24, and C3 decoder 25. The C1 decoder 23, C2 decoder 24, and C3 decoder 25 perform error correction processing on the C1 series, C2 series, and C3 series, respectively. C1 decoder 23, C
Each of the 2 decoder 24 and the C3 decoder 25 temporarily stores data in the memory 6 for each group and performs processing. Then, the C1 decoder 23 performs the correction process based on the error correction code C1 on a fragment basis, and the C2 decoder 24 performs the correction process using the error correction code C2 of the data string corresponding to the track direction. Further, the C3 decoder 25 uses the error correction code C3 to perform error correction processing in fragment units.

The data for which the error correction processing has been completed is separated into index information by the index separation circuit 26 and sent to the interface section 1. Then, it is output from the interface unit 1 to an external host computer.

The system controller 31 is formed by a microcomputer that controls the entire apparatus. That is, it controls the signal processing operation during recording / reproduction, the tape running operation, the rotating operation of the rotary head drum 50, and the like. Further, the servo circuit 30 actually performs the tape running operation and the rotary head drum 5 based on an instruction from the system controller 31.
The rotation operation of 0 will be executed. The servo circuit 30 can be formed by a microcomputer, and may be integrated with the system controller 31 as a circuit system having the function of the microcomputer as the system controller 31.

The rotating operation of the rotary head drum 50 is executed by the drum motor 33. A drum PG (pulse generator) 36 and a drum FG (frequency generator) 37 are attached to the rotary head drum 50, and pulses from this drum PG 36 are supplied to the servo circuit 30 via an amplifier 38. Also drum FG37
The pulse from is supplied to the servo circuit 30 via the amplifier 39. The servo circuit 30 includes a drum PG36 and a drum F.
A switching pulse can be generated according to the pulse from G37, and rotation phase information can be detected. The switching pulse is a signal that serves as a reference for switching processing corresponding to each of the so-called A azimuth head and B azimuth head.

The servo circuit 30 controls the drum PG36 to control the rotary head drum 50 at a constant speed.
Alternatively, rotation error information is obtained by detecting the rotation speed from the pulse from the drum FG 37 and comparing this with the reference rotation speed. Then, the drum servo signal S _D is generated based on the rotation error information, and the rotary head drum 50 is rotated at a constant speed by adjusting the drive signal applied from the drum motor driver 32 to the drum motor 33.

By controlling the rotation speed of the capstan 28, so-called tracking servo is performed. And in this example, as a tracking servo system,
The timing ATF method as described in FIG. 9 is adopted. The capstan 28 is rotationally driven by a capstan motor 35. A capstan FG (frequency generator) 40 is attached to the capstan 28, and the pulse from the capstan FG 40 is supplied to the servo circuit 30 via the amplifier 41.

In order to rotate the capstan 28 at a constant speed, the servo circuit 30 detects the rotation speed of the capstan 28 from the pulse from the capstan FG 40 and compares it with the reference rotation speed to obtain the rotation error information. obtain. Then, based on the rotation error information, the capstan servo signal S
_Constant speed rotation is performed by generating _CP and adjusting the drive signal applied from the capstan motor driver 34 to the capstan motor 35.

In order to execute the tracking servo further, the servo circuit 30 monitors the reference phase position timing of the rotary head drum 50 which can be detected from the switching pulse and the timing detection pulse TTP supplied from the timing detection pulse generation circuit 27. Then, the period is measured as the tracking detection period. Then, the tracking error information is obtained by comparing the measurement value of the tracking detection period with a preset reference value, and the capstan servo signal S _CP is generated based on the tracking error information, and the capstan motor driver 34 causes the capstan motor driver 34 to generate the capstan servo signal S _CP. Tracking servo is performed by adjusting the drive signal applied to the motor 35 to increase or decrease the rotation speed of the capstan 28.

3. Configuration and Operation for Timing ATF FIG. 3 shows the configuration of the circuit system for timing ATF operation. As a circuit system for the capstan servo including the timing ATF operation, a timing ATF processing unit 61, a switching pulse generation unit 62,
Free running counter 63, servo switch 64,
A capstan reference speed generator 65, a subtractor 66, and a speed servo signal generator 67 are provided.

When the tracking servo is turned off and the capstan 28 is driven to rotate at a constant speed, the servo on / off control signal T supplied from the system controller 31.
The servo switch 64 is turned _off by S _{ON / OFF} . In this case, the capstan reference speed generator 65 generates a signal corresponding to the speed desired to be set as the rotation speed of the capstan 28, and the signal is directly supplied to the speed servo signal generator 67 as the target speed signal CV. . Further, the speed servo signal generator 67 is supplied with a pulse FG _C from the capstan FG 40, that is, a pulse having a frequency corresponding to the rotation speed of the capstan 28, and the speed servo signal generator 67 receives the pulse FG _C from the pulse FG _C. The current rotation speed of the capstan 28 is detected.

Then, the speed servo signal generator 67 compares the current rotation speed that can be detected from the pulse FG _C with the target speed signal CV indicating the target rotation speed, and uses the error as the capstan servo signal S _CP. It is supplied to the capstan motor driver 34. The capstan motor driver 34 drives the capstan motor 35 by, for example, a three-phase drive signal to rotate the capstan 28, but by controlling the motor drive voltage according to the capstan servo signal S _CP , the capstan 28 is The constant speed rotation servo is executed so as to converge on the target speed signal CV generated from the capstan reference speed generation unit 65.

Therefore, the capstan reference speed generator 65
If the target speed signal CV generated from the above is set to the tape running speed (1x speed) during normal recording / reproducing, the capstan 28 is rotated at a constant speed of 1x speed, and the target speed signal CV is set to 2x speed. Then, the capstan 28 is rotated at a constant speed at a double speed. That is, the tape running speed can be varied by changing the target speed signal CV generated from the capstan reference speed generating section 65. The target speed signal CV generated by the capstan reference speed generator 65 may be controlled by the system controller 31 according to the operating state at that time. For example, 1x speed during playback,
During fast-forward playback of the tape, the speed can be changed to x-times speed.

When performing tracking control during reproduction, the servo switch 64 is turned on. Then, the timing ATF processing unit 61 detects the tracking error SV and subtracts the tracking error SV from the value generated by the capstan reference speed generating unit 65 by the subtractor 66, thereby generating the target speed signal CV. That is, in this case, the target speed signal CV is increased / decreased according to the tracking error SV centering on a predetermined speed (eg, 1 × speed). Therefore, the tape running speed is accelerated / decelerated around a predetermined speed according to the tracking state, and is thereby converged to the just tracking state. When the tracking is stable, the tracking error SV becomes almost zero, so that the tape running continues at an almost predetermined speed.

The tracking error SV detection process of the timing ATF processing unit 61 is performed based on the timing detection pulse TTP from the timing detection pulse generation circuit 27 and the switching pulse SWP generated by the switching pulse generation unit 62.

The timing detection pulse generation circuit 27 generates the timing detection pulse TTP from the data for which the header parity check has been completed from the header parity check circuit 21 as shown in FIG. The timing detection pulse TTP is a signal for measuring the tracking phase state, and is a pulse detected from a specific position on the track shown as the position P _TTP in FIG.

The timing detection pulse generation circuit 27 monitors the data read from the track TK of the tape 90 for the data detected from the sync signal area, the address / subcode area, and the header parity area, that is, the fragment header data. Therefore, according to the fragment address corresponding to the position P _TTP , the timing detection pulse TTP is generated from the synchronization signal or the like at that time.

FIG. 4D shows an image of the RF signal read from the tracks TK _A and TK _B , and FIG.
Indicates a timing detection pulse TTP generated by the timing detection pulse generation circuit 27. As can be seen from this figure, the timing detection pulse TTP is output at the timing corresponding to the reproduction scanning of a certain position P _TTP on the track during the reproduction scanning period of each track.

On the other hand, FIG. 4A shows an example of the pulse FG _D generated from the drum FG 37, and FIG. 4B shows an example of the pulse PG _D generated from the drum PG 36. Pulse F
Both G _D and pulse PG _D have a frequency corresponding to the rotation speed of the rotary head drum 50, and the pulse P
G _D is generated corresponding to a specific rotation phase position of the rotary head drum 50.

The switching pulse generator 62 generates the switching pulse SWP of FIG. 4C using the pulse FG _D and the pulse PG _D. For example, the switching pulse SWP is generated such that the rising edge of the pulse FG _D , which is the next timing after the detection of the pulse PG _D, is used as a reference, and the timing at which a predetermined delay time DL is given is the falling edge of the switching pulse SWP. . The switching pulse SWP is a signal that serves as a reference for switching between the A channel (reproducing head 16A) and the B channel (reproducing head 16B) for signal processing, and although not shown in FIG. It is also supplied to the circuit system.

The period in which the switching pulse SWP is at the "L" level is the processing period for the reproduced data from the reproducing head 16A, and the track TK _A is scanned by the reproducing head 16A during this period, as shown in FIG. 4 (d).
Data read from the track TK _A (RF
(A)) is performed. On the other hand, switching pulse SW
P is "H" level period becomes the processing period for reproducing data from the reproducing head 16B, the scanning by the reproducing head 16B with respect to the track TK _B in this period performed, Figure 4 from the track TK _B as (d) Data reading (RF (B)) is performed.

In the timing ATF processing section 61, the falling timing of the switching pulse SWP is tracked by the track TK.
Timing regarding _A The reference phase position of the rotating drum is used as the reference for the ATF operation. This corresponds to the timing TR _A in FIG. Then, as shown in FIG. 4, the tracking detection period M _TTP (A) from the timing TR _A until the timing detection pulse TTP is input is measured.
That is, the head outputs a predetermined signal (timing detection pulse TTP) from the track based on the reference phase position of the rotating drum.
The time to detect is to be measured.

The free running counter 63 is used for the measurement operation of the tracking detection period M _TTP (A). For example, the falling timing TR _A of the switching pulse SWP
Latches the count value of the free running counter 63, and latches the count value of the free running counter 63 at the input timing of the timing detection pulse TTP. Then, the tracking detection period M _TTP (A) can be measured by subtracting the two count values, and the measurement value as the tracking detection period can be obtained.

However, when considering the rotation unevenness of the rotary head drum 50, the tracking detection period M _TTP (A) measured in this way includes an error component due to the rotation unevenness. Therefore in the present embodiment, will be described in detail later, when the measurement of the tracking detection period M _TTP (A), are also conducted measurement errors caused by rotation unevenness, error component from the measured tracking detection period M _TTP (A) Is subtracted, and the measurement value of the tracking detection period M _TTP (A) in which the error component due to the uneven rotation is canceled is obtained. Then, the tracking detection period M _TTP (A) obtained in this way
Is compared with a preset reference value (reference value for track TK _A ) and the error is used as servo error information (tracking error SV) regarding track TK _A.

For the track TK _B , the rising timing of the switching pulse SWP is set to the timing ATF.
The timing TR _B is the reference phase position of the rotary drum which is the reference of the operation. Then, the tracking detection period M _TTP (B) from the timing TR _B until the timing detection pulse TTP is input is similarly set in the free running counter 6
3 is used for measurement. Then, after subtracting the error due to the uneven rotation measured at the same time from the measured value of the tracking detection period M _TTP (B) obtained in this way, a preset reference value (track TK _B
The error amount is used as servo error information (tracking error SV) regarding the track TK _B.

As described in the operation principle in FIG. 9, the tracking error SV thus obtained is input to the subtractor 66 and reflected in the target speed signal CV to control the rotation speed of the capstan 28. As a result, the relative speed between the drum rotation speed and the tape running speed is adjusted so that a good tracking state can be obtained.

4. Example of Tracking Servo Operation that Eliminates Influence of Rotational Error A specific operation of the timing ATF processing unit 61 when executing the above timing ATF servo operation will be described. FIG. 5 shows the internal structure of the timing ATF processing unit 61. That is, as a circuit system for calculating the tracking error SV for the timing ATF servo operation, a TTP input detection unit 71, a SWP edge detection unit 72,
TTP time register 73, SWP time register 74, rotation error detection time register 75, subtractors 76, 77, 7
8, 79, 80, reference value register 81, rotation error detection reference value memory 82, adders 83, 87, amplifiers 85, 8
6, a delay circuit 84, and a switch 89.

First, in order to execute the ATF tracking servo satisfactorily, the reference value must be set to an appropriate value. Although detailed description of the setting of the reference value is omitted, a certain tape reproducing operation for setting the reference value is executed at the time before the actual reproduction is started, and various types of tracks are set as described with reference to FIG. Samples of measurement values as the tracking detection period are collected in the scanning in the tracking phase state of, and the average value is obtained.

For example, with the tracking servo off (servo switch 64 in FIG. 3 off), the tape running speed is set to a speed different from the 1 × speed and the reproducing head 16 is set.
By performing reproduction scanning about 30 times by A and 16B respectively, the reproduction operation is executed so that various tracking phase states are obtained, and the tracking detection period is set for each track TK _A and TK _B. Collect a sample of measurements. Then, by taking the average of the samples, the reference value for A azimuth track TK _{A and} the reference value for B azimuth track TK _B are obtained,
This is stored in the reference value register 81 shown in FIG.

[0066] And as the actual playback time of the tracking servo operation, when the scanning of A azimuth track TK _A by reproducing heads 16A includes a reference value stored for A azimuth tracks TK _A, from the timing detection pulse as described above The tracking error SV is generated by comparing the measurement values of the measurable tracking detection periods. Also during scanning of the B azimuth track TK _B by reproducing head 16B is, B and the reference value stored for azimuth tracks TK _B, tracking by comparing the measured value of the tracking detection period can be measured from the timing detection pulse as described above errors Generate SV. However, in the case of the present example, after the error due to the rotation unevenness of the rotary head drum 50 is corrected with respect to the measurement value of the tracking detection period, the measurement value of the tracking detection period and the reference value register 81 are stored. It will be compared with the reference value. Such an operation is executed by the circuit system of FIG.

As the operation of the timing ATF processing section 61, the SWP edge detection section 72 shown in FIG. 5 performs edge detection on the switching pulse SWP from the switching pulse generation section 62. Then, the SWP edge detection unit 72 outputs an edge detection signal to the SWP time register 74 at the time when the falling edge or the rising edge of the switching pulse SWP is detected. This edge detection signal becomes a latch signal for the SWP time register 74.

The SWP time register 74 fetches the count value (FRC value) in the free running counter 63 at the timing when the edge detection signal is input and stores it. Therefore, at the timing when the falling edge of the switching pulse SWP is detected, the SWP time register 74 stores the value of the timing indicated by TR _A in FIG. Further, at the timing when the rising edge of the switching pulse SWP is detected, the SWP time register 74 stores the timing value indicated by TR _B in FIG.

On the other hand, the TTP input detection section 71 monitors the timing detection signal from the timing detection pulse generation section 27, and when the input is detected, the TTP time register 73 and the rotation error detection time register 75 are detected. T
Output a TP detection signal. This TTP detection signal is TTP
It becomes a latch signal for the time register 73. Therefore T
The TP time register 73 fetches the count value (FRC value) in the free running counter 63 at the timing when the TTP detection signal is input and stores it.
That is, the value of the detection timing of the timing detection pulse TTP is stored.

Further, the pulse FG _D from the drum FG 37 is supplied to the rotation error detection time register 75, and the first pulse FG after the TTP detection signal is input.
Free running counter 6 at the rising edge of _D
The count value (FRC value) in 3 is fetched and stored.

The timing value fetched in the TTP time register 73 and the timing value fetched in the SWP time register 74 are supplied to the subtractor 76 and subjected to subtraction processing. The output of the subtractor 76 is the switching pulse SW.
It becomes the value of the edge of P, that is, the period from the timing of the reference phase position of the rotary head drum 50 to the input timing of the timing detection pulse TTP, that is, the tracking detection period M _TTP (= M _TTP (A) or M _TTP shown in FIG. (B)). However, if rotation unevenness of the rotary head drum 50 occurs within this period, the value of the tracking detection period M _TTP output from the subtractor 76 includes an error due to rotation unevenness.

On the other hand, the timing value fetched in the rotation error detection time register 75 and the timing value fetched in the SWP time register 74 are supplied to the subtractor 77,
Subtraction processing is performed. The output of the subtracter 77 has a value of time to the timing of the pulses FG _D at the input timing near the timing detection pulse TTP from the edge timing of the switching pulse SWP, that is, the rotation error detection period STD shown in FIG. This rotation error detection period ST
D has a value close to the value of the period from the edge timing of the switching pulse SWP to the input timing of the timing detection pulse TTP, including the rotation unevenness.

Here, in the rotation error reference value memory 82,
Switching pulse S that can be detected by pulse FG _D
Timing detection pulse TT from WP edge timing
The value of the period until the input timing of P, that is, the rotation error detection period ST as a value close to the tracking detection period M _TTP
The ideal value of D is stored as the rotation error reference value STD _REF . Since the position P _{TTP at} which the timing detection pulse TTP is obtained is defined on the track, a pulse FG _D close to the input timing of the timing detection pulse TTP from the edge timing of the switching pulse SWP
The ideal time value of the period until the detection timing of can be calculated in advance. Here, "ideal" means that the rotary head drum 50 rotates at a constant speed without uneven rotation. For example, the pulse F within the period as the rotation error detection period STD
Since the pulse number of G _D can be specified, the rotation error reference value STD _REF can be calculated from the pulse number and the constant rotation speed.

The rotation error reference value STD _REF and the value of the rotation error detection period STD output from the subtractor 77 are supplied to the subtractor 78 and are subjected to subtraction processing. That is, subtraction is performed between the actual measurement value as the rotation error detection period STD and the ideal value. Therefore, the output of the subtractor 78 is the rotary head drum 50 during the period when the rotation error detection period STD is measured. Is a time value according to the rotation unevenness (speed fluctuation error).

The time value corresponding to this speed fluctuation is set by the switch 8
It is supplied to the subtractor 79 via 9. The subtractor 79 outputs the tracking detection period M _TTP output from the subtractor 76,
That is, the tracking detection period M _TTP as a measurement value including an error due to uneven rotation is also supplied, and the time value corresponding to the speed fluctuation is subtracted from the tracking detection period M _TTP .

The period during which the rotation error detection period STD is measured is substantially the same as the period during which the tracking detection period M _TTP is measured. Therefore, the rotation error detection period S
The speed fluctuation of the rotary head drum 50 detected as an error between the TD and the rotation error reference value STD _REF is also included in the measurement value of the tracking detection period M _{TTP in} exactly the same manner. Therefore, by the time value corresponding to the speed change from the measured tracking detection period M _TTP is subtracted, the tracking detection period M _TTP output from the subtracter 79 becomes an error due to rotation fluctuation is corrected values .

When the tracking detection period M _TTP in which the error due to the rotation fluctuation is corrected is obtained in this way, the subtracter 80 _{sets the} tracking detection period M _TTP between the reference value held in the reference value register 81. The subtraction is performed with. The error value which is the output of the subtractor 80 is given the integral control gain and the proportional control gain to be the tracking error SV. The proportional control gain is the gain K1 given by the amplifier 86. Further, as the integration control gain, the gain K2 is given to the integration processing signal by the 1-sample delay circuit 84 and the adder 83 by the amplifier 85.
Then, the outputs of the amplifiers 85 and 86 are added by the adder 87, and the tracking error SV is output.

As described above, the tracking error SV is subtracted from the value from the capstan reference speed generator 65 in the subtractor 66 shown in FIG. 3 to generate the target speed signal CV. Then, the capstan speed servo signal generator 67 compares the target speed signal CV with the current capstan speed to generate a capstan servo signal S _CP , thereby realizing tracking servo.

The switch 89 is controlled by, for example, the correction on / off signal H _{ON / OFF} from the system controller 31, and the switch 89 may be turned off when the correction based on the rotation fluctuation is not performed.

In the tracking servo operation of this example as described above, with respect to the measured value of the tracking detection period M _TTP ,
Since the error due to the uneven rotation of the rotary head drum 50 is corrected and the tracking error SV is generated based on this, the rounding of the tracking operation caused by the rotational fluctuation of the rotary head drum 50 is minimized. Therefore, the stability of the tracking servo can be greatly improved. As a result, it is possible to improve the error rate and the reliability of the reproducing apparatus.

In the above example, the measurement period of the rotation error detection period STD is set from the edge of the switching pulse SWP to the vicinity of the timing detection pulse TTP detection time, but it is not always necessary to do so. For example pulse PG _D
From the timing of 1 to the timing detection pulse TTP detection time point, or from the timing of the pulse FG _D immediately after the detection of the pulse PG _D to the timing detection pulse TTP detection time point. In any case, it is preferable to set a period that substantially matches the measurement period of the tracking detection period M _TTP . Of course, the rotation error reference value STD _REF should be an ideal time value according to the setting of the measurement period of the rotation error detection period STD.

Needless to say, the operation of generating the tracking error SV described as the operation of each circuit system in FIG. 5 can be actually performed by the arithmetic processing by the microcomputer. As the timing ATF operation, there are cases where a plurality of locations are set for one track and the timing detection pulse TTP is detected from each location to perform tracking control. However, the error component due to the uneven rotation of the present invention is corrected. The processing can be similarly applied to such a tracking operation method.

[0083]

As described above, in the reproducing apparatus of the present invention, the rotation error of the rotating drum during a period from the time when the rotating drum is near the reference phase position to the time when the head reaches the vicinity of the predetermined position on the track. Information is detected, the measured tracking detection period is corrected with the rotation error information, and then the corrected tracking detection period is compared with a reference value to generate a servo control signal. Therefore, the error component due to the rotation fluctuation is removed from the measurement value during the tracking detection period, and the servo control signal that is not affected by the rotation fluctuation can be generated, which improves the stability of the tracking servo and the error rate of the reproducing device. The effect is that the reliability can be improved.

As the rotation error information of the rotary drum, a signal synchronized with the rotation of the rotary drum, such as an FG pulse, is used.
Measure the period from a certain time when the rotating drum is near the reference phase position to the time when the head reaches the vicinity of a predetermined position on the track, and obtain it by comparing with the ideal rotation error reference value. By doing so, the rotation error information can be detected easily and accurately.

[Brief description of drawings]

FIG. 1 is a block diagram of a recording / reproducing apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a rotary head drum of the recording / reproducing apparatus of the embodiment.

FIG. 3 is a block diagram of a capstan servo system of the recording / reproducing apparatus of the embodiment.

FIG. 4 is an explanatory diagram of an operation of a capstan servo system of the recording / reproducing apparatus of the embodiment.

FIG. 5 is a block diagram of a tracking error generation circuit system for timing ATF in the embodiment.

FIG. 6 is an explanatory diagram of tracks formed on a DDS3 type tape.

FIG. 7 is an explanatory diagram of a track format in the DDS3 system.

FIG. 8 is an explanatory diagram of a track of a helical scan system.

FIG. 9 is an explanatory diagram of a timing ATF operation.

FIG. 10 is an explanatory diagram of a reference value setting operation for timing ATF.

[Explanation of symbols]

1 interface section, 2 index addition circuit,
3 C3 encoder, 4 C2 encoder, 5 C1 encoder, 6 memory, 7 subcode addition circuit, 8
Subcode generator, 9 Header parity addition circuit, 10
8/10 modulation circuit, 11 sync signal addition circuit, 12
Margin adding circuit, 13 recording amplifier, 14, 17 rotary transformer, 15, 15A, 15B recording head, 16, 16A, 16B reproducing head, 18 reproducing amplifier, 19 sync signal detecting circuit, 20 10/8 demodulating circuit, 21 header parity Check circuit, 22 subcode separation circuit, 23 C1 decoder, 24 C2 decoder, 25 C3 decoder, 26 index separation circuit, 27 timing detection pulse generation circuit, 28 capstan, 29 pinch roller, 30 servo circuit, 3
1 system controller, 32 drum motor driver, 33 drum motor, 34 capstan motor driver, 35 capstan motor, 36 drum P
G, 37 drum FG, 38, 39, 41 amplifier, 4
0 Capstan FG, 50 rotating head drum, 61
Timing ATF processor, 62 switching pulse generator, 63 free running counter, 64 servo switch, 65 capstan reference speed generator, 66
Subtractor, 67 Speed servo signal generation section, 71 TTP input detection section, 72 SWP edge detection section, 73 TTP time register, 74 SWP time register, 75 Rotation error detection time register, 76, 77, 78, 79, 80
Subtractor, 81 Reference value register, 82 Rotation error detection reference value memory, 83,85 Adder, 85,86 Amplifier, 84 Delay circuit

Claims (2)

[Claims] 1. When reproducing data recorded as an inclined track on a tape-shaped recording medium by a head arranged on a rotating drum, the rotating drum reaches a reference phase position within one rotation cycle. Measuring the tracking detection period up to the point when the timing detection signal is obtained by the head corresponding to the predetermined position on the track, and comparing the measured value of this tracking detection period with the reference value of the set tracking detection period. As a reproducing device for performing a tracking servo by generating a servo control signal with respect to the relative speed of the running speed of the tape-shaped recording medium and the rotating speed of the rotating drum, the rotating drum is near the reference phase position. From the time when the head reaches the vicinity of the predetermined position on the track. Drum rotation error detecting means for detecting the rotation error information of the above, and tracking detection from the time when the rotating drum reaches the reference phase position to the time when the head reaches the predetermined position on the track and a timing detection signal is obtained. Tracking detection period measuring means for measuring the period, and the tracking detection period measured by the tracking detection period measuring means is corrected by the rotation error information detected by the drum rotation error detecting means, and the corrected tracking is performed. And a servo control signal generating means for generating a servo control signal by comparing a detection period with the reference value. 2. The drum rotation error detecting means receives the head near a predetermined position on a track from a certain time point when the rotary drum is near the reference phase position by a signal synchronized with the rotation of the rotary drum. 2. The reproducing apparatus according to claim 1, wherein the rotation error information of the rotary drum is detected by measuring the period up to and comparing the measured value with a preset rotation error reference value.