JP3042553B2 - Signal reproducing apparatus and method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal reproducing apparatus and method suitable for, for example, a video tape recorder (VTR).

[0002]

2. Description of the Related Art JP-A-63-100563 discloses that
A VTR that performs tracking control of a magnetic head is disclosed. In this VTR, at the time of recording, recording tracks TA, TB, TA, TB,... Formed sequentially by two magnetic heads HA, HB on a magnetic tape.
At frequencies f1, f2, f3, f4, f1,. . . . The four kinds of pilot signals for the tracking servo which change cyclically are recorded as described above, and at the time of reproduction, tracking control is performed by detecting signal leakage of both adjacent tracks.

On the other hand, in a new pulse code modulation (hereinafter, referred to as “PCM”) system of a high band 8 mm VTR,
A start flag and an edit flag are recorded as the ID signal.

[0004]

The recording signal such as the ID signal needs to be reliably reproduced, especially at the time of high-speed search such as FF (fast forward) / REW (fast reverse).

The present invention has been made in view of such circumstances, and has as its object to provide a signal reproducing apparatus capable of reliably reproducing a recorded signal.

[0006]

A signal reproducing device according to claim 1 reproduces a signal recorded on a recording medium.
And tracking of signals reproduced by the reproducing means
Generator that generates a tracking error signal from the signal for
And a tracking error signal generated by the generating means.
Control the tracking state of the playback means based on the signal
Control means and recording of signals reproduced by the reproduction means
The error is detected from the data component recorded on the medium.
First detecting means for outputting the first detection means;
Tracking status of the playback means based on the detected error
Generates a shift signal that shifts the
And an adding means for adding to the tracking error signal.
The adding means calculates the tracking state of the reproducing means in units.
Unit shift means for shifting a plurality of times by the shift amount of
And the number of shifts of the tracking state of the playback means
The counting means for counting and the tracking state of the reproducing means are shifted.
Error detected by the first detection means
The second detection is to detect that
Of the recording / reproducing means counted by the output means and the counting means.
The number of times the racking state has been shifted and the
Based on the detection result, the tracking status of the playback
Determining means for determining the shift amount .

According to a second aspect of the present invention, there is provided a signal reproducing method comprising the steps of:
A playback step of playing back the signal recorded on the body,
Tracking of signals reproduced in raw step processing
Generating a tracking error signal from the signal for
Steps and trackings generated in the generation step
Tracking at the playback step based on the
Control step for controlling the playback state and processing of the playback step
Data recorded on the recording medium among the signals reproduced in
First detecting step of detecting the error from the data component
Based on the error detected in the process of the first detection step.
The tracking state in the playback step
Generates a shift signal to shift by the shift amount and
An adding step for adding to the king error signal.
In the calculation step, the tracking state in the playback step is
Unit shift to shift multiple times by the unit shift amount
The tracking status in the step and the playback step can be shifted.
Counting step to count the number of times
As a result of shifting the tracking state of
Error detected by the
A second detection step of detecting
Tracking in the recording / reproduction step
The number of times the switching state has shifted, and the number of detections in the second detection step.
Tracking status in the playback step based on the result
And a determining step of determining the shift amount .

[0008]

The signal reproducing apparatus according to claim 1 and the signal reproducing apparatus according to claim 2
In the signal reproduction method described in
Signal is reproduced, and the track
A tracking error signal is generated from the signal for
The tracking error is generated based on the generated tracking error signal.
The king state is controlled, and the recording medium
The error is detected from the data components recorded in
Tracking status based on detected errors
Shift signal that shifts the
Is added to the tracking error signal and tracked.
The switching state is shifted multiple times by the unit shift amount.
The number of times the tracking state is shifted is counted and the
Errors detected as a result of shifting the racking state
Is detected to decrease and then increase,
The number of times the tracking state has shifted
Detection result that the error which has once decreased and then increases
The shift amount of the tracking state is determined based on the
You.

[0009]

[0010]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. In this embodiment, the present invention is applied to an 8 mm VTR. A pair of magnetic heads HA and HB having different azimuth angles are provided on the rotating drum 1.
It is mounted at an angular interval of 80 °. Also,
The magnetic tape 2 is run obliquely around the peripheral surface of the rotary drum 1 within an angle range of 216 °. On the magnetic tape 2, a video signal, an FM audio signal and a tracking servo pilot signal are recorded in a range of 180 ° out of the above 216 °, and a PCM audio signal and a tracking servo pilot signal are recorded in a range of 36 °. Is recorded.

The magnetic heads HA and HB make one revolution in one frame, the magnetic head HA scans over the magnetic tape 2 in an odd-numbered field, and the magnetic head HB in an even-numbered field.
Are configured to scan over the magnetic tape 2. During recording, the magnetic heads HA and HB are placed on the magnetic tape 2.
Thus, recording tracks TA and TB (not shown, see JP-A-63-100653) which are inclined are formed alternately and sequentially. The recording tracks TA, TB, TA, TB,... Formed in this manner have frequencies f1, f.
2, f3, f4, f1,. . . . The pilot signals for the four types of tracking servos, which cyclically change as shown in FIG. 3, are a video signal (a composite signal of a low-frequency conversion color signal and an FM modulation luminance signal), an audio FM (AFM) signal, and a PCM audio signal. It is recorded by frequency multiplexing.

The frequencies f1 to f4 of the pilot signal are
The lower band color signal is selected on the lower side of the band, for example, 102.544 kHz, 118.951 kHz, 16
5.210 kHz and 148.689 kHz, and the frequency of the pilot signal of a certain recording track and the pilot signal of an adjacent recording track is Δf _A = f _H (about 1
6 kHz), Δf _B = 3f _H (about 47 kHz) (where f
_H is the horizontal frequency).

At the time of reproduction, reproduction signals obtained from the magnetic heads HA and HB are supplied to a rotary transformer RA, respectively.
After the signals are amplified by the reproduction amplifiers 3A and 3B via the input terminals 4 and 4 of the head switch 4,
A and 4B. The head changeover switch 4 is synchronized with the rotational phase of the magnetic heads HA and HB.
A so-called RF switching pulse is supplied as a switching control signal, and the head changeover switch 4 connects the 4A side (first channel CH1) for one field period during which the magnetic head HA scans over the magnetic tape 2, During one field period in which the magnetic head HB scans over the magnetic tape 2, the 4B side (second channel) is connected.

The reproduction signal output from the head changeover switch 4 is separated into a low-frequency conversion color signal and a frequency-modulated luminance signal in a video reproduction signal processing system 70 and subjected to predetermined processing to obtain a reproduction color video signal. Can be

A reproduction signal output from the head changeover switch 4 is processed by an AFM reproduction signal processing system 60, from which an audio FM signal is output.

A reproduction signal output from the head changeover switch 4 is processed by a PCM reproduction signal processing system 20, from which a PCM signal is output, and an error is detected by an error detection circuit 22. The error amount is supplied to the system controller 100.

A continuous reproduced signal output from the head changeover switch 4 is supplied to a pilot signal detecting circuit 5 having a low-pass filter configuration. The pilot signal detected by the detection circuit 5 is supplied to a multiplication circuit 6.
Reference numeral 7 denotes a frequency signal generation circuit.
Generates signals of frequencies f1, f2, f3, and f4, and supplies them to the switch circuit 8.

The system controller 100 performs the processing shown in FIG. 3 according to the error amount supplied from the error detection circuit 22 to change the tracking shift amount of the magnetic heads HA and HB so that the error is minimized. The reference pilot switching control signal is supplied to the switch circuit 8 in order to control the generation timing of the reference pilot signal. The relationship between the change in the generation timing of the reference pilot signal and the change in the tracking shift amount of the magnetic heads HA and HB is described in JP-A-63-100563.
Since it is disclosed in Japanese Patent Laid-Open Publication No. H10-209, it will not be described here.

From the switch circuit 8, when there is no error, a signal having a frequency equal to the frequency (f1 to f4) of the pilot signal of the recording tracks TA and TB to be scanned by the magnetic heads HA and HB in each field period. Is output. The output signal of the switch circuit 8 is supplied to the multiplication circuit 6 as a reference pilot signal. In the multiplication circuit 6, the pilot signal from the detection circuit 5 and the switch circuit 8
Is multiplied by the reference pilot signal.

The output signal of the multiplying circuit 6 is supplied to the detection circuit 9A of a band pass filter difference is constituted by the frequency Delta] f _A, the output signal of the detection circuit 9A peak - click detection circuit 10
A, and the output signal of the peak detection circuit 10A is supplied to input terminals 11A and 12B of the changeover switches 11 and 12, respectively. The output signal of the multiplication circuit 6 is a difference frequency Δ constituted by a bandpass filter.
is supplied to the detection circuit 9B of f _B, the output signal of the detection circuit 9B is peak - it is supplied to the click detection circuit 10B, the peak - the input terminals 11B of the output signal of the click detector 10B is changeover switch 11 and 12 And 12A.

An RF switching pulse is supplied from the system controller 100 to the changeover switches 11 and 12 as a changeover control signal.
And 12 are switched to 11A and 12A, respectively, when the head switch 4 is switched to the 4A side, and are switched to 11B and 12B, respectively, when the head switch 4 is switched to the 4B side. The changeover switches 11 and 12
Are supplied to the comparator 13 respectively.

From the comparator 13, for example, S1 = S2
When S1> S2, a positive signal having a level corresponding to the difference is output, and when S1 <S2, a negative signal having a level corresponding to the difference is output.

Here, when the magnetic head HA is in the recording track T
When scanning A, the frequency Δ output from the multiplication circuit 6
level of the difference frequency signal f _A and Delta] f _B becomes the same level when the scanning position is in the center, along with better scanning position of the level of the previous difference frequency signal of the frequency Delta] f _B enough to biased the recording track side becomes larger The level of the difference frequency signal of the frequency Δf _A increases as the scanning position shifts toward the later recording track.

For this reason, the peak detection circuits 10A and 10A
The level of the output signal 0B is the same when the scanning position is at the center, and the level of the output signal of the peak detection circuit 10A becomes higher as the scanning position is shifted toward the later recording track side, and the scanning position becomes higher. The level of the output signal of the peak detection circuit 10B increases as the position approaches the previous recording track.

On the other hand, when the magnetic head HB is
Is scanned, the level relationship of the difference frequency signal between the frequencies ΔfA and ΔfB is opposite to that when the magnetic head HA scans the recording track TA as described above.
Therefore, the level relationship between the output signals of the peak detection circuits 10A and 10B is also opposite to that when the magnetic head HA scans the recording track TA.

However, the changeover switches 11 and 12
Is that the magnetic head HA is connected to the sides 11A and 12A during one field period for scanning the recording track TA, while the magnetic head HB is connected to the sides 11B and 12B during one field period for scanning the recording track TB. , The magnetic heads HA and HB respectively have recording tracks TA and TB
When scanning is performed, the levels of the output signals S1 and S2 of the changeover switches 11 and 12 are the same when the scanning position is at the center, and the output signal S1 becomes larger as the scanning position is shifted toward the later recording track. At the same time, as the scanning position shifts toward the preceding recording track, the signal S2 becomes larger. Therefore, when the magnetic heads HA and HB scan the magnetic tracks TA and TB, respectively, the comparator 13 determines that the scanning position is zero when the scanning position is at the center, and that the scanning position is shifted toward the later recording track side. When a positive signal having a proportional level is offset toward the previous recording track, a negative signal having a level proportional to the magnitude of the offset is output.

Reference numeral 14 denotes a capstan motor, 15 denotes a motor drive circuit for controlling its rotation, and 16 denotes a frequency generator for generating a frequency signal corresponding to the rotation speed of the capstan motor 14. The frequency signal from the frequency generator 16 is supplied to a speed servo circuit 17, and the speed error signal from the speed servo circuit 17 is subjected to a mode error via an adder 18.
Is supplied to the data drive circuit 15. Thus, the rotation speed of the capstan motor 14 is controlled to be constant.

The output signal of the comparator 13 is
The signal is supplied to the motor drive circuit 15 via the adder 18 as an ATF error signal (phase error signal) _EATF .
As a result, the rotational phase of the capstan motor 14 is controlled, and the magnetic heads HA and HB correctly scan the center positions of the recording tracks TA and TB, respectively, so that a so-called tracking servo is performed.

FIG. 2 shows the PCM reproduction signal processing system 20 shown in FIG.
2 shows a configuration example of an error detection circuit 22. The reproduction signal supplied from the switch 4 is supplied to the comparison input terminal of the comparator 204 via the equalizer 202. The reference input terminal of the comparator 202 has a variable voltage source 20
6 supplies a reference voltage. The output of the comparator 204 is supplied to the data input terminal of the D-type flip-flop 210 and to the reproduction PLL 208. From the reproduction PLL 208, a clock signal synchronized with the output of the comparator 210N is supplied to the clock input terminal of the D-type flip-flop 210. Thereby, the comparator 2 is output from the Q output terminal of the D-type flip-flop 210.
The output signal 04 is shaped and output.

The output signal of the D-type flip-flop 210 is converted into an NRZ code by an NRZ conversion circuit 212, converted into parallel data by a serial / parallel converter 214, and fetched by a data fetch circuit 216. The data fetched by the data fetch circuit 216 is decoded by the 8-10 decoding circuit 218, latched by the latch 220, supplied to the PCM signal processing system, and supplied to the error detection circuit 22. The error detection circuit 22 detects an error by a syndrome operation.

FIG. 3 shows the system controller 10 of FIG.
An example of a zero tracking control operation is shown. First, in step S1, the tracking shift amount Δt
Is set to 0 as an initial value. Further, error detection is performed, and the detected error amount e ₀ is stored in the error register (step S2). Further, since the tracking control routine is in a loop, 0 is set as an initial value of the number of loops N (step S).
3).

Next, the value of N is incremented by one (step S4), and the tracking route shift amount Δt is incremented by a unit amount in the positive direction (step S4).
5). In FIG. 3, the unit amount increment in the positive direction is
Indicated by +1. The increment of the unit amount of the tracking shift amount in the positive direction is performed by controlling the switch circuit 8 so as to move the generation timing of the reference pilot signal in the first direction on the time axis for a predetermined time. Subsequently, the error detection, the detected error amount e ₁ is stored in the error register (step S
6). Next, a magnitude comparison between the error amounts e ₀ and e ₁ is performed,
If e ₀ is larger than e ₁ , the tracking shift amount is further incremented by a unit amount in the positive direction (step S
8, S4, S5 and S6).

If e ₁ is greater than or equal to e ₀ in step S7, the tracking shift amount Δt is incremented by a unit amount in the negative direction (step S9). In FIG. 3, the unit amount increment in the negative direction is indicated by -1. The unit increment of the tracking shift amount in the negative direction is performed by controlling the switch circuit 8 so as to move the generation timing of the reference pilot signal in the second direction on the time axis for a predetermined time. Since N is 1 at this time, the result of the determination in step S10 is NO, and the process proceeds to step S11. In step S11, the tracking route shift amount Δt is again incremented by a unit amount in the negative direction. Subsequently, the error detection, the detected error amount e ₂ is stored in the error register (step S12). Next, a magnitude comparison between the error amounts e ₀ and e ₂ is performed, and if e ₀ is greater than e ₂ ,
The tracking shift amount is incremented by a unit amount in the negative direction (steps S14, S11 and S12).

If e ₂ is greater than or equal to e ₀ in step S15, the tracking route shift amount Δ
t is incremented by a unit amount in the positive direction (step S1).
5), the process ends.

When the tracking control routine is performed twice (YES in step S10), the process ends.

It should be noted that the unit amount increment loop of the tracking shift amount Δt in the positive direction (steps S4 and S4)
5, S6, S7, and S8), the step S9 of incrementing the tracking shift amount Δt by a unit amount in the negative direction is inserted because the tracking shift amount Δt is increased by a unit amount increment loop in the positive direction. This is to correct that the unit amount increment in the direction is one more, and to make it come to the best point when N becomes 2 or more (YES in step S10) (FIG. 4).

FIG. 5 shows the configuration of another embodiment of the present invention. 5, the same components as those in FIG. 1 are denoted by the same reference numerals. In this embodiment, the system controller 1
00A receives the output of the error detection circuit 22, performs the processing of FIG. 3, and controls the output voltage of the variable voltage source 42 to change the tracking shift amount of the magnetic heads HA and HB so that the error is minimized. A control signal is supplied to the variable voltage source 42 in order to do so. Output of comparator 13 and variable voltage source 4
The output of 2 is added by the adder 41 and supplied to the adder 18. Changes in the output of the voltage source 42 and the magnetic head HA
The relationship between the HB and the change in the tracking shift amount of HB is disclosed in JP-A-63-100563, and will not be described here.

FIG. 6 shows the configuration of another embodiment of the present invention. 6, the same components as those in FIG. 1 are denoted by the same reference numerals. In this embodiment, the system controller 1
00B receives the output of the error detection circuit 22, performs the processing of FIG. 3, and changes the tracking shift amounts of the magnetic heads HA and HB so that the error is minimized.
A control signal is supplied to a level control circuit 52 provided between the switch 12 and the comparator 13. The relationship between the change in the output of the level control circuit 52 and the change in the tracking shift amount of the magnetic heads HA and HB is disclosed in Japanese Patent Application Laid-Open No. 63-100563, and will not be described here.

In the above embodiment, the error is detected by the syndrome calculation. However, the error may be detected by using the CRC.

Although the above embodiment relates to a VTR, the present invention is not limited to the VTR, and is applicable to various signal reproducing apparatuses for performing tracking control of reading means for reading a signal recorded on a recording medium. it can.

[0041]

According to the present invention, there is provided a signal reproducing apparatus and a signal reproducing apparatus , comprising:
According to the signal reproducing method of claim 2, the tracking state
If the state is shifted multiple times by the unit shift amount,
First, count the number of times the racking state has shifted, and
As a result of shifting the locking state, the error
After that, it was detected that the increase was counted and tracked
The number of times the switching state has shifted and the error has once decreased
Later, based on the detection result of increase, tracking
Since the shift amount of the state is determined,
The recorded signal can be reliably reproduced.

[0042]

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration example of a PCM reproduction signal processing system 20 and an error detection circuit 22 of FIG.

FIG. 3 is a flowchart illustrating an example of a tracking control operation of the system controller 100 of FIG. 1;

FIG. 4 is a graph showing a relationship between an error amount and a tracking shift amount in the tracking control operation of FIG. 3;

FIG. 5 is a block diagram showing a configuration of another embodiment of the present invention.

FIG. 6 is a block diagram showing a configuration of another embodiment of the present invention.

[Explanation of symbols]

 2 Magnetic Tape 8 Switch Circuit 14 Capstan Motor 15 Motor Drive Circuit 20 PCM Reproduction Signal Processing System 22 Error Detection Circuit 41 Adder 42 Variable Voltage Source 51 Level Control Circuit 100, 100A, 100B System Controller

Claims (2)

(57) [Claims] 1. A method for reproducing a signal recorded on a recording medium.
That in the signal reproducing apparatus, reproducing means for reproducing a signal recorded on the recording medium
And tracking among signals reproduced by the reproducing means.
Generator that generates a tracking error signal from the signal for
Stage and the tracking error generated by the generating means
The tracking state of the reproducing means is controlled based on the signal.
Controlling means, and the recording medium among signals reproduced by the reproducing means.
Error from data components recorded in
First detecting means , based on the error detected by the first detecting means.
The tracking state of the reproducing means is changed by a predetermined shift.
Generates a shift signal for shifting by the
Adding means for adding to the king error signal , wherein the adding means changes the tracking state of the reproducing means without a unit shift amount.
The unit shift means for shifting a plurality of times and the number of times the tracking state of the reproducing means is shifted.
As a result of shifting the tracking state of the counting means and the reproducing means,
The error detected by the first detecting means is temporarily
Second detection means for detecting increase after decrease
And the track of the recording / reproducing means counted by the counting means.
The number of times the switching state has been shifted and the detection of the second detection means.
Based on the output result,
A signal reproducing apparatus comprising: a determination unit that determines a shift amount . 2. A method for reproducing a signal recorded on a recording medium.
A signal reproducing method of a signal reproducing apparatus for reproducing a signal recorded on the recording medium.
-Up and, track out of the signal reproduced by processing of the reproduction step
To generate a signal Karato tracking error signal for the King
A generating step and the tracking generated in the processing of the generating step
Based on the error signal, the track in the reproducing step
A controlling step of controlling the playback state; and the signal reproduced in the processing of the reproducing step.
From the data components recorded on the recording medium, the error
A first detecting step of detecting, and the error detected in the processing of the first detecting step
Based on the tracking state in the reproducing step
Generates a shift signal that shifts the
And an adding step for adding to the tracking error signal.
The adding step includes a step of shifting the tracking state in the reproducing step by a unit.
Unit shift step to shift multiple times by
And the number of times the tracking state has been shifted in the reproduction step.
A counting step of counting the number and a result of shifting the tracking state in the reproduction step.
As a result, the error detected by the first detection step is detected.
Is detected to decrease once and then increase.
A detecting step and a recording / reproducing step counted in the processing of the counting step.
The number of times the tracking state was shifted in
The reproduction step is performed based on the detection result in the detection step.
Step to determine the shift amount of the tracking state in the
Signal reproducing method characterized by comprising a-up.