JP2878528B2 - Magnetic recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a helical scanning type magnetic recording / reproducing apparatus, and more particularly to an ATF (Automatic Track Finding) using pilot signals of different frequencies sequentially recorded on a helical track for tracking control during reproduction.
ing) The present invention relates to a magnetic recording / reproducing apparatus adopting the system.

[0002]

2. Description of the Related Art A conventional ATF tracking type magnetic recording / reproducing apparatus using a pilot signal is disclosed in, for example, JP-A-59-68862, JP-A-59-75450, and JP-A-59-36358. Etc. are shown.
Also, this ATF tracking method has been adopted in a VTR called 8 mm video which has recently become widespread. Here, the ATF tracking method will be briefly described.

In the ATF tracking method, pilot signals f1 to f4 are sequentially superimposed on recording information and recorded for each helical track. These four-frequency pilot signals are 378 fH in the case of an NTSC VTR.
(FH: horizontal synchronizing signal frequency of the television signal = 15.73
4kHz) of 1/58, 1/50, 1 /
36, 1/40 frequency signal, f1 ≒
6.5fH, f2 ≒ 7.5fH, f3 ≒ 10.5fH,
f4 ≒ 9.5 fH (the source vibration is 375 fH in a CCIR VTR). Therefore,
The pilot signal frequency difference between adjacent tracks on the magnetic tape is always fH or 3fH (strictly speaking, it is 16.407 kHz, 16.521 kHz or 46.145 kHz, 46.209 kHz. FH and 3fH for convenience). For example, when the magnetic head scans the f2 track during reproduction, the frequency difference between the f1 pilot signal of the preceding adjacent track and the f2 pilot signal of the scanning track is fH, and the f3 pilot signal of the following adjacent track and the scanning track are different. F
The frequency difference from the two pilot signals is 3fH.
At this time, the reproduced pilot signals include f1, f2, which are pilot signals of the scanning track and both adjacent tracks.
f3 is included. Therefore, a pilot signal f2 of a track to be scanned is selected as a local pilot signal,
If the reproduction pilot signal is multiplied, the pilot signals of both adjacent tracks are converted into fH and 3fH frequencies. At this time, the reproduced f2 pilot signal of the scanning track becomes a 0 beat signal. The fH and 3fH signals are extracted and detected by a BPF (Band Pass Filter), and the level of the track scanned by the magnetic head, that is, the tracking phase is detected by comparing the fH signal level and the 3fH signal level. By feeding back the tracking phase detection signal to the capstan motor, reproduction tracking control is performed.

[0004]

However, in a conventional ATF tracking system using a four-frequency pilot signal, frequency conversion of a reproduced pilot signal and fH
And BPF for extracting the 3fH component, level detection, and level comparison between the fH signal and the 3fH signal are performed by analog signal processing. Therefore, the ATF tracking control system as described above is compatible with a tape speed control system which is almost digitally processed or software-processed by a microcomputer or a drum speed and phase control system equipped with a magnetic head. Is getting worse. In other words, since the ATF tracking control system uses analog signal processing, it is difficult to achieve high integration with other digital control systems.
Also, the BPF that extracts fH and 3fH components that greatly affect the performance of the ATF tracking control also suffers from characteristic degradation due to variations in components and aging in analog signal processing.

Accordingly, an object of the present invention is to realize digital integration or software processing of ATF tracking control to realize high integration integrated with other control systems, and to reduce performance deterioration due to variations in components and aging. An object of the present invention is to provide a magnetic recording / reproducing apparatus capable of performing no tracking control.

[0006]

In order to achieve the above object, in a magnetic recording / reproducing apparatus according to the present invention, first, a basic configuration of a control system unit detects a rotation speed and a rotation phase of a rotary drum as digital signals. First and second detecting means, third detecting means for detecting the running speed of the magnetic tape as a digital signal, LPF (low-pass filter) means for extracting a pilot signal component from the reproduced signal, A to convert to digital signal
D conversion means; memory means for storing the pilot signal data converted into the digital signal;
Digital signal processing means for receiving the output signals of the second and third detection means and the memory means and for processing the digital signals in accordance with a predetermined program, wherein the digital signal processing means comprises A first control signal for controlling the speed and phase of the rotating drum is generated from the output signal of the second detection, and a second control signal for controlling the speed of the magnetic tape is generated from the output signal of the third detecting means. Generating a third control signal for performing tracking control from the output signal of the memory means,
Is supplied to the rotary drum motor, and after adding the second control signal and the third control signal, the control signal is supplied to the magnetic tape running motor.

As the digital processing of the ATF tracking control system, first, the AD conversion means converts the reproduced pilot signal into a digital signal at a sampling frequency which is a common multiple of the four pilot signals. The output stage of the AD conversion means includes sampling data thinning means for converting the sampling frequency to a sampling frequency of twice or less of a predetermined pilot signal, and the memory means converts the output data of the thinning means to a thinning rate (sampling frequency). Only the number of data determined by the conversion rate is stored. The digital signal processing means extracts a return signal of a reproduced pilot signal of a predetermined track from the digital pilot signal data supplied from the memory means, and detects a level of the return pilot signal extracted by the digital filter means. A level detection unit; and a calculation unit that generates a tracking error signal from the level detection signal. The digital signal processing means includes a controller, a register, a multiplier, an adder,
It has a data selector, a counter, a ROM, a RAM and the like, and processes input data in accordance with a program recorded on the ROM.

[0008]

The first, second and third detecting means detect the rotation speed and rotation phase of the rotary drum and the running speed of the magnetic tape as digital signals. The LPF means suppresses unnecessary high frequency signals such as video signals and extracts only pilot signals necessary for tracking. The AD conversion means and the sampling data thinning means positively utilize the fact that a signal having a frequency exceeding 1/2 of the sampling frequency is detected as aliasing in sampling, and perform frequency conversion of the reproduced pilot signal. The memory means temporarily stores the reproduced pilot signal to be detected and distributes the time required for pilot signal processing in the digital signal processing means. The digital filter extracts the reproduced pilot signal components of both adjacent tracks from the folded reproduced pilot signal stored in the memory. The level detecting means detects the levels of the reproduced pilot signals from both adjacent tracks. That is, the tracking state is detected. The calculating means generates a tracking control signal by obtaining a level difference between reproduced pilot signals from both adjacent tracks.

The digital signal processing means performs the first and second time-division processing in parallel with the pilot signal processing.
And comparing and calculating the rotational speed information, rotational phase information, and magnetic tape traveling speed information supplied from the third detecting means with each control target value to control the rotational speed and phase of the rotary drum. And a second control signal for controlling the speed of the magnetic tape. The first control signal is supplied to the rotary drum motor, and the rotary drum rotates at a constant speed and a predetermined phase. After the second control signal and the tracking control signal are added, the first control signal is supplied to the capstan motor and the magnetic tape is fixed. The vehicle travels in a predetermined speed tracking state.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. First, a first embodiment will be described with reference to FIGS. FIG. 1 shows a magnetic recording / reproducing apparatus (8
FIG. 3 is a block diagram showing a millimeter VTR. In FIG.
1 is a magnetic tape, 2a and 2b are magnetic heads, 3 is a drum, 4 is a drum motor, and 5 is a DFG (Drum Frequency Ge).
nerator) sensor, 6 is DPG (Drum Pulse Generato)
r) Sensor (so-called tack pulse sensor), 7 is a capstan, 8 is a capstan motor, 9 is a CFG (Capstan).
Frequency Generator) Sensor, 10 is preamplifier, 1
1 is a video / audio processing circuit, 12 is a video / audio input / output terminal, 1
3 is a sensor amplifier, 14 is a drum rotation speed detection circuit, 1
5 is a drum rotation phase detection circuit, 16 is a capstan rotation speed detection circuit, 17 is a capstan rotation phase detection circuit,
18 is an analog LPF, 19 amplifier, 20 is an AD converter, 21 is a digital LPF, 22 and 23 are data thinning circuits, 26 is a DSP (digital signal processor), 27 is a clock generator, 28 is a mode control signal input terminal, 29 , 30 are DA converters, and 31 and 32 are motor driver amplifiers.

First, the drum control system will be described. In FIG. 1, a DFG signal which is a frequency signal proportional to the rotation speed of the drum motor 4 generated by the DFG sensor 5 and a DPG signal which is a rotation phase detection signal of the drum motor 4 generated by the DPG sensor 6 are , After being amplified by the sensor amplifier 13, the drum rotation speed detection circuit 14,
It is supplied to the drum rotation phase detection circuit 15 and the DSP 26. The drum rotation speed detection circuit 14 measures the period of the DFG signal and supplies speed data to the DSP 26. The drum rotation phase detection circuit 15 measures a phase difference between the DPG signal and the reference phase signal and supplies phase data to the DSP 26.
The DSP 26 calculates a predetermined drum speed target value and a predetermined drum phase target value in accordance with the mode control signal supplied via the input terminal 28, and calculates the speed data and the phase data, and calculates a speed error signal and a speed error signal. Generate a phase error signal. After adding the speed error signal and the phase error signal, the signals are supplied to the DA converter 29. The DA converter 29 converts a drum control signal, which is an addition signal of the speed error signal and the phase error signal, into an analog signal and supplies the analog signal to the motor driver amplifier 31. The motor driver amplifier 31 amplifies the power of the drum control signal and drives the drum motor 4. Thus, the drum 4 rotates at a desired speed and phase.

Next, the capstan control system will be described. The capstan control differs between recording and reproduction. First, at the time of recording, a CFG signal, which is a frequency signal proportional to the rotation speed of the capstan motor 8 and is generated by the CFG sensor 9, is amplified by the sensor amplifier 13. It is supplied to the stun rotation phase detection circuit 17 and the DSP 26.
The capstan rotation speed detection circuit 16 measures the cycle of the CFG signal and supplies speed data to the DSP 26. The capstan rotation phase detection circuit 17 measures the phase difference between the CFG signal and the reference phase signal, and supplies phase data to the DSP 26. The DSP 26 calculates a predetermined capstan speed target value and a predetermined capstan phase target value in accordance with the mode control signal supplied via the input terminal 28, and calculates the measured speed data and phase data to obtain a speed error. Generate a signal and a phase error signal. Then, after adding the speed error signal and the phase error signal, the signals are supplied to the DA converter 30. The DA converter 30 converts a capstan control signal, which is an addition signal of the speed error signal and the phase error signal, into an analog signal and supplies the analog signal to the motor driver amplifier 32. The motor driver amplifier 32
The power of the capstan control signal is amplified and the capstan motor 8 is driven. As described above, the capstan 7
The magnetic tape 1 rotates at a desired speed and phase, and runs at a desired speed. On the other hand, in the capstan control at the time of reproduction, ATF tracking control is performed instead of the phase control system. Therefore, the capstan rotation phase detection circuit 17 stops operating, the DSP 26 also stops generating the capstan phase error signal, and the A
The TF tracking error signal is added to the capstan speed error signal and supplied to the DA converter 30 as a capstan control signal.

The above DFG signal, DPG signal, C
The signal processing in the DSP 26 related to the FG signal is D
The FG signal, the DPG signal, and the CFG signal are processed at the timing of being directly input to the DSP 26, and are processed by the AT
The priority is set higher than the F tracking error signal processing.

Next, an ATF tracking control system during reproduction will be described. In FIG. 1, a reproduction signal detected by the magnetic heads 2a and 2b from the magnetic tape 1 is supplied to an analog LPF 18 after being amplified by a preamplifier 10. The analog LPF 18 suppresses high frequency components such as video or audio information unnecessary for tracking control from the reproduced signal and extracts a reproduced pilot signal. The reproduced pilot signal is amplified by the amplifier 19 to a level suitable for the input dynamic range of the AD converter 20 at the next stage. The AD converter 20 converts the reproduced pilot signal into a digital signal at a sampling frequency that is a common multiple of the four-frequency pilot signal frequencies f1 to f4. In this embodiment, the sampling frequency is the least common multiple of 189f.
H (this value is for an NTSC VTR, C
187.5fH in the case of the CIR method). The reproduced pilot signal converted into a digital signal is, for example, a digital LP of a 4-tap moving average processing type.
In F21, the video signal and the audio signal that have not been sufficiently suppressed by the analog LPF 18 are effectively suppressed and supplied to the data thinning circuits 22 and 23. In the data thinning circuits 22 and 23, according to the control clock supplied from the DSP 26, the reproduced pilot signal data having a sampling frequency of 189fH is sequentially divided by 1/29, 1/25, 1/20, 1 / at the track scanning cycle (field cycle). 18
Thinning out so that the sampling frequency becomes. Note that the thinning-out here means, for example, in the case of 1/29 thinning-out, one piece of data is sequentially extracted from 29 pieces of 189fH sampling data, and the remaining 28 pieces of data are discarded. Therefore, the sampling frequency is changed to four pilot signal frequencies f1 (≒ 6.5 fH), f2 (≒ 7.5 fH), f
4 (≒ 9.5 fH) and f3 (≒ 10.5 fH). As a result of the conversion of the sampling frequency, the reproduced pilot signal of the four frequencies produces a reproduced pilot folded signal of the frequency as shown in FIG.

The reproduced pilot signal whose sampling frequency has been converted by the data thinning circuits 22 and 23 is supplied to the DSP 26. The DSP 26 processes the reproduced pilot signal data according to a predetermined program, and generates an ATF tracking error signal. The reproduction pilot signal processing of the DSP 26 is executed by the software according to the program as described above. However, in order to facilitate understanding of the processing contents, description will be given using the hardware configuration example of FIG. FIG. 3 shows an AT using a reproduced pilot signal.
2 shows an example of a hardware configuration of an F tracking error signal generating means. Hereinafter, the operation of FIG. 3 will be described.

In FIG. 3, the blocks 20 to 23 are:
It is the same as the block of the same reference numeral shown in FIG. 3, reference numeral 33 denotes an input terminal of a reproduced pilot signal, 34 denotes an input terminal of a clock supplied from the master clock generator 27 shown in FIG. 1, 35 denotes an input terminal of a field control signal, 36 denotes a control clock generation circuit, 37,
38 is an fH-BPF, 39 and 40 are envelope detection circuits, 41 is an arithmetic circuit, 42 is a latch circuit, 43 is a characteristic compensation filter, and 44 is an output terminal of a tracking error signal.

In FIG. 3, reproduced pilot signal data supplied through an input terminal 33, an AD converter 20, and a digital LPF 21 is supplied to a data thinning circuit 22, 2.
3 is supplied. The data thinning circuits 22 and 23 convert reproduced pilot signal data having a sampling frequency of 189 fH into 1/29, 1/25, 1/20, 1/2 according to the thinning clock supplied from the control clock generating circuit 36.
The sampling frequency is thinned out so as to be any one of the sampling frequencies 18. This thinning rate is performed according to the field control signal supplied from the input terminal 35. The ATF tracking control is to control the level of reproduced pilot signals from both tracks adjacent to a track (hereinafter, referred to as a main track) scanned by the magnetic head. Further, as shown in FIG. 2, the pilot signals can be all converted into fH signals by selecting the sampling frequency. In this embodiment, the necessary reproduced pilot signals are converted into fH signals and detected. Like that. Therefore, for example, when the magnetic head is scanning a track on which the f2 pilot signal is recorded, the reproduced pilot signal f on both adjacent tracks is scanned.
It is necessary to detect the pilot signals of 1 and f3.
Therefore, the data thinning rate of the data thinning circuit 22 is set to 1
/ 25 (sampling frequency = f2), the f1 pilot signal is converted into an fH signal, and the data thinning rate of the data thinning circuit 23 is 1/20 (sampling frequency = f2).
4) to convert the f3 pilot signal into an fH signal. The reproduced pilot signal frequency-converted by the data decimation circuits 22 and 23 is fH-BPF3
7, 38. The fH-BPFs 37 and 38 extract the fH signal components from the reproduced pilot signals and supply them to the envelope detection circuits 39 and 40. Therefore,
In the above case, the fH-frequency output of the fH-BPF 37 is
It becomes the reproduced f1 pilot signal, and the fH-BPF 38 f
The H frequency output becomes a reproduced f3 pilot signal. The envelope detection circuits 39 and 40 perform envelope detection of the reproduced pilot signal converted and extracted into the fH signal,
The amplitude information is supplied to the arithmetic circuit 41.

As the magnetic tape runs, the scanning track (main track) changes from f2 to f3 to f4 to f1 to f2.
, The data thinning circuits 22 and 23
The thinning rate is set according to the field control signal, and the conversion sampling frequency is changed from f2 → f3 → f4 → f
1 → f2 and f4 → f1 → f2 → f3 → f4.
Thus, the reproduced pilot signals extracted by the fH-BPFs 37 and 38 and envelope-detected by the envelope detection circuits 39 and 40 are f1 → f2 → f3 → f4 →
f1 and f3 → f4 → f1 → f2 → f3. Therefore, the output signal of the envelope detection circuit 39 always becomes the amplitude information of the pilot signal of the preceding adjacent track,
The output signal of the envelope detection circuit 40 always becomes the amplitude information of the pilot signal of the succeeding adjacent track. The arithmetic circuit 41 subtracts the pilot signal amplitude information of the preceding adjacent track from the pilot signal amplitude information of the succeeding adjacent track, and supplies a tracking error signal as a difference signal to the latch circuit 42. The latch circuit 42 functions as a hold circuit, and prevents discontinuity of pilot signal amplitude information generated at a track switching point or the like from being output. The tracking error signal in which the discontinuity point is held at the previous value in the latch circuit 42 is output from an output terminal 44 via a characteristic compensation filter 43 for improving the characteristics of tracking control. This tracking error signal is added to the capstan speed error signal as described above, and output as a capstan control signal.

Here, a specific configuration example of the fH-BPFs 37 and 38 and the envelope detection circuits 39 and 40 in the ATF tracking error signal means will be described with reference to FIGS. 4 and 5. FIG. In this embodiment, fH-B
The PFs 37 and 38 are constituted by, for example, IIR digital filters in the block shown in FIG. 4, which are equivalent to the second-order analog band-pass filters. In FIG. 4, 45 is an input terminal, 46 and 47 are adders, 48 is a subtractor, and 49 and 50.
Is a latch circuit, 51 to 53 are coefficient circuits (multiplication circuits),
Reference numeral 54 denotes an output terminal. This digital fH-B
The transfer function of the PF is represented by the following (Equation 1).

[0020]

(Equation 1)

In the above equation (Equation 1), the sampling period of the digital filter is determined by the data thinning circuits 22 and 23.
, The coefficients k, α, and β corresponding to each sampling frequency are set in order to obtain desired filter characteristics.

FIG. 5 shows a configuration example of the envelope detection circuits 39 and 40. In FIG. 5, 55 is a data input terminal, 56 is a clock input terminal, 57 is a magnitude comparison circuit,
58 and 59 are latch circuits, and 60 is a data output terminal. 5, the fH signal data supplied from the input terminal 55 is supplied to a magnitude comparison circuit 57 and a latch circuit 58. The magnitude comparison circuit 57 performs magnitude comparison between the input fH signal data and the latch data of the latch circuit 58,
When the input fH signal data is large, a latch clock is output to the latch circuit 58. Therefore, the latch circuit 58
Will sequentially latch the maximum value of the input fH signal data. Then, the latch circuit 58 is reset at the cycle (1 / fH or more) of the clock supplied through the input terminal 56, and the other latch circuit 59 stores the data of the latch circuit 58 immediately before the reset. Is latched and output via the output terminal 60, so that the maximum value data of the fH signal can be latched at the cycle of the clock supplied via the input terminal 56, and the output signal is the envelope detection signal of the input fH signal. Becomes If the clock supplied through the input terminal 56 is the same as that of the envelope detection circuits 39 and 40 shown in FIG. 4, the sampling frequency (output data data) of the output signal data in the envelope detection circuits 39 and 40 is used. Rate) is determined by the latch frequency of the latch circuit 59 in the output stage, so that the input fH
Even if the sampling frequencies of the signals are different, the sampling frequencies of the envelope detection signal data supplied to the next-stage arithmetic circuit 41 can be made equal, and the arithmetic (subtraction) processing can be easily performed.

The operation of the DSP 26 including the ATF tracking error signal generating means has been described above using the example of the hardware configuration. Hereinafter, the example of the software configuration for processing according to the program will be described with reference to the program charts of FIGS. It will be described using FIG. FIG. 6 shows fH-BPF
7 is a chart of the envelope detection processing, FIG. 8 is a chart of the overall processing of the DSP 26, FIG. 9 is a chart of the drum speed control system, FIG. 10 is a chart of the drum phase control system, and FIG. 11 is a capstan speed control. It is a system chart. In the fH-BPF processing chart of FIG. 6, P (n-1) and P (n-2) are data of the latch circuits 49 and 50 shown in FIG.
(N) is input / output data of the fH-BPF processing. FIG.
In the envelope detection processing chart of FIG.
Is the data of the latch circuit 58 shown in FIG. 5, Cn is the number of data of the input fH signal in one cycle of the clock supplied through the input terminal 56 shown in FIG.
(N) and Z (n) are input / output data of the envelope detection processing. In the overall processing chart of the DSP 26 shown in FIG. 8, the mode decoding processing means that the mode of the system is determined by decoding the mode control signal supplied via the input terminal 28, and the control target of the drum and the capstan is controlled. And so on. The speed control of the drum and the capstan needs to be set to a wider band than the ATF tracking control band. Therefore, in order to minimize the delay time due to the processing, the interrupt processing is performed and the processing is performed with high priority. . In FIG. 8, the portion inserted in the triangle represents the interrupt processing. Processing routines for drum speed control, drum phase control, and capstan speed control are as shown in FIGS. 9, 10, and 11.

As described above, according to the present embodiment, 4
The digital processing of the reproduced pilot signal of frequency
Since the sampling frequency at the time of D conversion is set to a frequency which is a common multiple of the pilot signal and the sampling data is thinned out, all four reproduced pilot signals can be converted into fH frequency signals, so that there is no need to provide a separate frequency conversion multiplier circuit. Thus, the circuit can be downsized. Also,
Since the digital processing of the reproduction pilot signal is performed by software processing using a DSP, it is possible to integrate one chip into an LSI including other control systems such as drum speed / phase control and capstan speed control. Circuit can be downsized. Moreover, a BPF for extracting an fH component that greatly affects the performance of the ATF tracking control system
And an envelope detection circuit or the like can be realized by a digital circuit, and the characteristic deterioration due to the variation of component parts and the aging that has become a problem at the time of analog signal processing can be prevented.

In the first embodiment, the digital processing of the pilot signal is realized at a low sampling frequency by positively using the loopback signal. When the fH-BPF processing and the envelope detection processing shown in FIGS. 6 and 7 are performed by the DSP 26, a considerably high operation speed is required. Therefore, in the second embodiment described below, digital processing of a pilot signal can be realized by a DSP having a low operation speed.

FIGS. 12 and 13 are block diagrams showing a magnetic recording / reproducing apparatus (8 mm VTR) and ATF tracking error signal generating means according to the second embodiment. 12 and 13, the difference from the magnetic recording / reproducing apparatus described with reference to FIGS. 1 and 3 in the hardware configuration is that memories 24 and 25 are provided. In addition,
Except for ATF pilot signal processing by software in the memories 24 and 25 and the DSP 26, each block operates in the same manner as in FIGS.
The operation of the memories 24 and 25 and the ATF pilot signal processing by software in the DSP 26 will be described.

Referring to FIG. 12 and FIG.
Reproduced pilot signals whose sampling frequencies have been converted by the data thinning circuits 22 and 23 are stored in the units 4 and 25 with a predetermined number of data as one unit (the predetermined number of data is hereinafter referred to as a block, and details thereof will be described later). . The reproduced pilot signal data stored in the memories 24 and 25 is sequentially supplied to the DSP 26. The DSP 26 processes the reproduced pilot signal data according to a predetermined program as described in the above embodiment, and generates an ATF tracking error signal. The memories 24 and 25
Is one of the most important items in the present invention.
Hereinafter, the number of data in one block will be described.

First, consider the characteristics of a digital fH-BPF for extracting an fH-converted pilot signal. In this embodiment, the selectivity Q is set to about Q = 10 to 20 in consideration of the S / N and the transient response characteristics of the extracted fH signal. In the case of such a Q value, an input signal of 100 to several hundred samples is required for the output amplitude to be stabilized in consideration of the transient response characteristics. Of course, in this case the input f
The phase continuity of the H signal component is necessary.

Next, fH-BPF input signal fH
Consider the relationship between the converted pilot signal frequency (the frequency of the pilot signal to be detected) and the sampling frequency. This relationship is shown in FIG. 14 from the relationship between the frequency of each pilot signal and each sampling frequency after the data is decimated. In FIG. 14, the relationship between each sampling frequency and the fH-converted pilot signal frequency (shown as f * 'in the table) is f1: f2' = 25: 4, f2: f
1 ′ = 29: 4, f3: f4 ′ = 10: 1 (30:
3), f4: f3 ′ = 9: 1 (27: 3). Therefore, in the case of sampling frequencies f1 to f4, if signal processing is performed on 25, 29, 10, and 9 samples as one unit, that is, as one block, the phase continuity of each fH-converted pilot signal is maintained. Become.
For example, the fH-converted f1 pilot signal is
When extracting with F, data sampled at the f2 pilot signal frequency is first processed into 29 data,
Even discarding the next 29 data, processing the next 29 × 3 data, discarding the next 29 × 2 data, and so on, even processing the 29 data in one block. For example, the phase continuity of the fH-converted f1 pilot signal is maintained, and the fH-BPF can extract the fH signal.

In consideration of the above, in the present embodiment, the reproduced pilot signals to be detected are f1, f2, f3, f4,
That is, the sampling frequency after thinning is f2, f1, f
In the case of 4, f3, the number of data stored in the memories 24, 25 is set to 29, 25, 27, and 30. Specifically, for example, when the magnetic head is scanning the f2 pilot signal track, it is necessary to detect the pilot signals f1 and f3, which are the reproduction pilot signals of the adjacent tracks. Therefore, the data thinning rate of the data thinning circuit 22 is set to 1/25 (sampling frequency = f2), the f1 pilot signal is converted into an fH signal, and the data thinning rate of the data thinning circuit 23 is reduced to 1/25.
20 (sampling frequency = f4), and convert the f3 pilot signal into an fH signal. Data thinning circuit 22,
The reproduced pilot signal frequency-converted by 23 is stored in memories 24 and 25 in units of 29 data and 27 data, respectively. The stored fH-converted data is sequentially supplied to the DSP 26 and subjected to the fH-BPF processing and envelope detection processing shown in FIGS. The fH-converted pilot signal data supplied from the data thinning circuits 22 and 23 supplied during the processing period of the DSP 26 is discarded in 29 data units and 27 data units, respectively.
When the processing of SP26 ends, the next 29 data and 27
The data is stored in the memories 24 and 25 and processed.
Then, as the magnetic tape runs, the scanning track becomes f2.
As the order of f3 → f4 → f1 → f2, the data thinning circuits 22 and 23 are set with the thinning rate according to the field control signal, and set the conversion sampling frequency to f2 → f3 → f4 → f1 → f2 and f4 → f1 →
f2 → f3 → f4. Thereby, the memory 24,
The number of data stored in 25 is 29 → 30 → 27 → 25 → 29, and 27 → 25 → 29 → 3
0 → 27.

As described above, according to the present embodiment, in addition to the effects of the first embodiment, the time required for digital processing of the reproduced pilot signal in the DSP can be reduced, and a DSP having a low operating speed can be used. All digital control becomes possible, and when a one-chip LSI is used, low cost and low power consumption can be realized.

In this embodiment, the memories 24, 25
Is set to 29, 25, 27, and 30. As can be seen from the above description, this number is different from the sampling frequency of f1, f2, f3, and f4. Multiples of 25, multiples of 29, multiples of 10,
It is clear that a similar effect can be obtained even when a multiple of 9 is used.

Next, a description will be given of a third embodiment in which the concept of the second embodiment is further advanced. The basic idea of the third embodiment is as follows. A control band of ATF tracking control (a band having a loop gain of 1 or more) is, for example, at most several H in the case of an 8 mm video currently manufactured.
z. Therefore, the final output sampling frequency of the ATF tracking control signal is several tens Hz to 10 Hz.
Even if it is set to 0 and several tens of Hz, almost no problem occurs. Therefore, instead of always generating the ATF tracking error signal by the reproduction pilot signal processing, the AT by the reproduction pilot signal processing is performed only at several timings in the head scanning period (each field period) of each track.
An F-tracking error signal is generated, and the previous value is held during other periods. In the third embodiment, as a means according to the above concept, the hardware configuration is the same as that of the second embodiment shown in FIGS.
The software processing of the reproduced pilot signal in the DSP 26 has been changed. Hereinafter, generation of the ATF tracking error signal by the reproduction pilot signal processing in the DSP 26 will be described.

As described with reference to FIG. 14 in the second embodiment, the sampling frequency after data decimation is a multiple of 25, 29, 29 for f1, f2, f3, and f4.
If the processing is performed in units of multiples, multiples of 10, and multiples of 9, the phase of the fH-converted pilot signal can be correctly extracted by the fH-BPF while maintaining the continuity. Therefore, in one field period, the thinned data is stored in the memories 24 and 25 only at the timing of 1/4 field and 3/4 field from the switching point of the field, and the stored data is sequentially supplied to the DSP 26 a plurality of times. The number of data stored in the memories 24 and 25 at this time is set to be the same as that of the second embodiment, and the sampling frequency after thinning is f2, f1, f
For 4, f3, the number of stored data is 29, 25, 27
And 30 pieces. The DSP 26 has a sequential memory 2
The fH signal component is extracted by fH-BPF processing by reading the data of 4, 25 and the fH-BPF processing.
Since the input signal data of the sample is required, the data stored in the memories 24 and 25 are repeatedly used to obtain fH-B
The filter processing is performed up to the number of data necessary for stabilizing the amplitude of the fH signal output of the PF. For example, fH-BPF
Is about 13, the total data processing required to stabilize the amplitude of the fH signal output is about 120 data. Also in this case, since the data stored in the memories 24 and 25 maintain the phase continuity of the fH signal component, the fH signal output of the fH-BPF has accurate amplitude information. fH extracted by fH-BPF processing
The converted pilot signal is subjected to envelope detection, but in this embodiment, since the processing of fH-BPF is the processing of the same input data, the envelope detection is performed by fH-BPF.
The fH output data of the last block of the processing may be processed.

D for performing the above-described reproduction pilot signal processing
An example of the software configuration of the SP 26 is shown in FIGS.
This will be described with reference to the program chart of FIG. FIG. 15 shows fH
16 is a chart of the BPF processing, FIG. 16 is a chart of the envelope detection processing, and its basic configuration is the chart of the fH-BPF processing of FIG. 6 described in the first embodiment and the chart of the envelope detection processing of FIG. Is the same. The difference is that in the chart of the fH-BPF processing in FIG. 15, the data stored in the memory is used a plurality of times (Cm times), so that an "m" loop is provided. Note that Cn is the number of data stored in the memory. And FIG.
In the chart of the envelope detection processing, the envelope detection may be performed by processing the fH output data of the last block of the fH-BPF processing. Therefore, it is determined whether to perform the envelope detection processing based on the value of “Cm”. ing.

The amplitude information of the reproduced pilot signals from both adjacent tracks detected by the fH-BPF processing and the envelope detection processing is subtracted by the arithmetic circuit 41 shown in FIG.
Supplied to Since the tracking error signal is generated only at the timing of 1/4 field and 3/4 field from the switching point of the field, the latch circuit 42 outputs the hold signal during other periods.

As described above, according to the present embodiment, in addition to the effects of the first embodiment, the time required for digital processing of the reproduced pilot signal in the DSP can be greatly reduced. All digital control can be performed using a DSP whose operation speed is slower than that of the DSP, and when a one-chip LSI is used, further reduction in cost and power consumption can be realized.

DS in the first to third embodiments described above
FIG. 17 shows a specific configuration example of P. In FIG. 17, 6
1 is a master clock input terminal, 62 is an interrupt processing signal input terminal, 63 is an input / output port, 64 is a controller, 65 is a program counter, 66 is a stack memory, 67 is a program ROM, 68 and 75 are registers, 69 , 73 are data selectors, 70 is RAM, 7
1 is a shift register, 72 is a multiplier, and 74 is an adder. In the DSP shown in FIG. 17, first, the program data is read from the ROM 67 by the address generated by the program counter 65. The controller 64
Decode the above program, control each block,
It performs desired digital signal processing such as addition, subtraction, multiplication, division, comparison, logical operation, and judgment of data.

[0039]

As described above, according to the present invention,
The ATF tracking control system is digitalized or software-processed on a small scale, enabling high-level integration including other control systems such as drum speed / phase control and capstan speed control. It is possible to realize a high-performance tracking performance without performance degradation due to component variations and aging.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a main configuration of a magnetic recording and reproducing apparatus according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a reproduced pilot loopback signal frequency after thinning according to the first embodiment of the present invention.

FIG. 3 is a block diagram showing a hardware configuration for performing ATF pilot signal processing according to the first embodiment of the present invention.

FIG. 4 is a block diagram showing one example of a digital fH-BPF of FIG. 3;

FIG. 5 is a block diagram illustrating an example of the envelope detection circuit of FIG. 3;

FIG. 6 is a program chart of an fH-BPF process according to the first embodiment of the present invention.

FIG. 7 is a program chart of an envelope detection process according to the first embodiment of the present invention.

FIG. 8 is a program chart of the overall processing of the DSP according to the first embodiment of the present invention.

FIG. 9 is a program chart diagram of a drum speed control system according to the first embodiment of the present invention.

FIG. 10 is a program chart diagram of a drum phase control system according to the first embodiment of the present invention.

FIG. 11 is a program chart diagram of a capstan speed control system according to the first embodiment of the present invention.

FIG. 12 is a block diagram illustrating a main configuration of a magnetic recording and reproducing apparatus according to a second embodiment of the present invention.

FIG. 13 is a block diagram showing a hardware configuration for performing ATF pilot signal processing according to a second embodiment of the present invention.

FIG. 14 is an explanatory diagram illustrating a relationship between an fH-converted pilot signal frequency and a sampling frequency according to the second embodiment of the present invention.

FIG. 15 is a program chart of an fH-BPF process according to a third embodiment of the present invention.

FIG. 16 is a program chart diagram of an envelope detection process according to a third embodiment of the present invention.

FIG. 17 is a block diagram showing an example of a configuration of a digital signal processor used in the first to third embodiments of the present invention.

[Explanation of symbols]

 14 Drum rotation speed detection circuit 15 Drum rotation phase detection circuit 16 Capstan rotation speed detection circuit 18 Analog LPF 20 AD converter 21 Digital LPF 22, 23 Data thinning circuit 24, 25 Memory 26 DSP (Digital Signal Processor) 29, 30 DA converter 36 control clock generation circuit 37, 38 fH-BPF 39, 40 envelope detection circuit 41 arithmetic circuit 42 latch circuit 43 characteristic compensation filter 46, 47 adder 48 subtractor 49, 50 latch circuit 51, 52, 53 coefficient circuit (multiplication circuit) ) 57 size comparison circuit 58,59 latch circuit 64 controller 65 program counter 66 stack memory 67 ROM 68,75 register 69,73 data selector 70 RAM 71 shift register Star 72 multiplier 74 adder

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroya Abe 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside Hitachi, Ltd. Visual Media Research Laboratories (72) Inventor Akishi Mikabe 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Hitachi, Ltd. Visual Media Research Laboratories (72) Inventor Yukinobu Tada 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Hitachi, Ltd. Video Media Research Laboratories (72) Inventor Yoshio Narita 1410 Inada Inada, Katsuta-shi, Ibaraki Stock Hitachi, Ltd. AV Equipment Division (56) References JP-A-62-33356 (JP, A) JP-A-60-243849 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) ) G11B 15/467

Claims (6)

(57) [Claims] 1. A tracking control pilot signal is multiplexed with an information signal and recorded on a track formed on a magnetic tape by helical scanning of a magnetic head mounted on a rotating drum, and a reproduction signal of the pilot signal is reproduced at the time of reproduction. A first and a second detecting means for detecting a rotation speed and a rotation phase of a rotating drum as a digital signal; and detecting a running speed of a magnetic tape as a digital signal. A third detecting means, an AD converting means for converting a reproduced pilot signal into a digital signal, and output signals of the first, second, and third detecting means and the AD converting means. Digital signal processing means for processing digital signals in accordance with a program. The processing means generates a first control signal for controlling the speed and phase of the rotating drum from the output signals of the first and second detection means, and determines the speed of the magnetic tape from the output signal of the third detection means. Generating a second control signal for performing control; generating a third control signal for performing tracking control from an output signal of the AD conversion means; supplying the first control signal to a rotary drum motor; After adding the control signal and the third control signal, the control signal and the third control signal are supplied to the magnetic tape traveling motor. Further, the sampling frequency conversion means for converting the sampling frequency of the output signal of the AD conversion means, and the sampling frequency conversion means Data storage means for storing an output signal, and supplying the data stored in the data storage means to the digital signal processing means, And a third control signal for performing the following. 2. A tracking control pilot signal is multiplexed with an information signal and recorded on a track formed on a magnetic tape by helical scanning of a magnetic head mounted on a rotating drum, and a reproduced signal of the pilot signal is reproduced during reproduction. A magnetic recording / reproducing apparatus that performs tracking control in accordance with the following: A / D converting means for converting a reproduced pilot signal into a digital signal; a sampling frequency converting means for converting a sampling frequency of an output signal of the A / D converting means; Digital signal processing means for generating a tracking control signal from the frequency-converted reproduced pilot signal, wherein the relationship between the frequency fp of the reproduced pilot signal to be detected by the digital signal processing means and the converted sampling frequency fs is fp: fs = N: M (N and M are self Wherein the digital signal processing means generates the tracking control signal from the reproduced pilot signal data by using the reproduced pilot signal processing as a unit of M integer multiples of data when the numbers are mutually prime. Recording and playback device. 3. A tracking control pilot signal is multiplexed with an information signal and recorded on a track formed on a magnetic tape by helical scanning of a magnetic head mounted on a rotary drum, and a reproduced signal of the pilot signal is reproduced during reproduction. A magnetic recording / reproducing apparatus configured to perform tracking control according to the following: an A / D converter for converting a reproduced pilot signal into a digital signal; a sampling frequency converter for converting a sampling frequency of an output signal of the A / D converter; Data storage means for storing an output signal of the sampling frequency conversion means, and digital signal processing means for generating a tracking control signal using data stored in the data storage means; Reproduced pilot signal frequency fp and converted sampler When the relationship with the frequency fs is fp: fs = N: M (N and M are natural numbers and relatively prime), the number of data stored in the data storage means is set to M integer multiples. Characteristic magnetic recording / reproducing device. 4. The digital signal processing means according to claim 3, wherein said digital signal processing means extracts a predetermined reproduced pilot signal, and said envelope detection means detects amplitude information of an output signal of said band pass filter means. Computing means for generating a tracking control signal from the output signal of the envelope detecting means, and when generating a tracking control signal from the reproduced pilot signal, the reproduced pilot signal data stored in the data storage means is divided into M pieces of data. A magnetic recording / reproducing apparatus characterized in that data is overlapped a plurality of times as one unit and supplied to the band pass filter means. 5. The method according to claim 1, wherein the pilot signal is a four-frequency pilot signal that can be sequentially switched in a track scanning cycle, and the sampling frequency in the AD converter is a common multiple frequency of the four-frequency pilot signal. A magnetic recording / reproducing apparatus, wherein the sampling frequency after the conversion by the sampling frequency conversion means is a predetermined pilot signal frequency in the four-frequency pilot signal. 6. The apparatus according to claim 5, wherein the pilot signal frequencies of the four frequencies (f1, f2, f3, f4) are f1 = 378fH / 58 and f2 = 378fH when the recording information signal is an NTSC video signal. / 5
0, f3 = 378fH / 36, f4 = 378fH / 40
If the recording information signal is a CCIR video signal, f1 = 375fH / 58 and f2 = 375fH / 5.
0, f3 = 375fH / 36, f4 = 375fH / 40
(FH is a horizontal synchronizing signal frequency of a video signal).