JP2866327B2 - Automatic tracking device for magnetic recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION The present invention relates to a helical scan system.
Related to the automatic tracking device of the magnetic recording and reproducing device
In particular, the envelope level of the playback signal is maximized.
In this way, the running phase of the magnetic tape is controlled
1. Field of the Invention The present invention relates to an automatic tracking device for a recording and reproducing device. [0002] 2. Description of the Related Art Conventionally, helical scan type home magnets are used.
Recording / reproducing device (hereinafter simply referred to as VTR)
The video head runs precisely on the track on the magnetic tape
Tracking control is performed as
Conventionally, as one of the tracking controls, from the magnetic tape
The phase difference between the reproduced control signal and the reference signal
The rotation phase of the capstan motor should be
(Hence the running phase of the magnetic tape)
A known method is known. On the other hand, a conventional VTR generally has a magnetic tape.
It is configured to be able to select the playback mode with different running speeds of the
Usually, the standard playback mode and magnetic tape than this
3x speed playback mode where the running speed of the
I have. By the way, in such a VTR,
A dedicated video head is provided for each playback mode.
In addition, these dedicated video heads
Because they are staggered, you can switch between these playback modes.
Is the best tracking condition (i.e., the video head is
Rotating the video head while scanning the track
The relationship between the phase and the phase of the control signal is different. Follow
The cylinder motor that rotates the video head
Generally, a common reference signal is used in the two reproduction modes.
Because the rotation phase is controlled, the rotation of the capstan motor
Each of the above reference signals for controlling the phase inversion
The phase must be different between the playback modes. Therefore, in such a VTR, a reproduction mode
When the mode is started, or 3 times the standard playback mode
Capstan motor with switching between fast regeneration modes
Automatically adjusts reference signal phase for rotational phase control
Requires an automatic tracking device. [0006] As such an auto tracking device,
Conventionally, various proposals have been made.
As disclosed in JP-A-53-90910, a reproduced signal
Tracking control signal using the envelope level of
Detected, and the envelope level is
So that the running phase of the magnetic tape is controlled
There is an automatic tracking device that has been developed. [0007] This automatic tracking device is a magnetic tape device.
Position of the video head in its width direction relative to the track on the
(Hereinafter referred to as tracking phase, the length of the track)
When the center line of the video head matches the center line of
Assuming that the racking phase is zero,
When the track is shifted by the track pitch,
In general, FIG.
As shown in the figure, the envelope level of the reproduced signal
The raw envelope level)
It is a thing. This playback envelope level is
King phase When 2nπ, maximum When (2n-1) π, the minimum And it changes like a sine wave.
Level, and the running phase of the magnetic tape
By changing the tracking phase by controlling
What can maximize the playback envelope level
It is. [0008] The auto tracking device periodically
Samples the playback envelope level, and
There is a difference between the ring value and the previous sampling value
And the video head is displaced by a predetermined amount in the track width direction.
The tracking phase by changing the running phase of the magnetic tape
To change the phase of the signal. FIG. 10 (a), (b)
As shown in the figure, the tracking phase is sequentially changed to reproduce
When the envelope level increases, the sampling
The value also tends to increase gradually, and the playback envelope level
Where the maximum is the sampling value
Turn a little. Auto tracking device sampling
Automatically search for the tracking phase where the value changes from increasing to decreasing
It is. [0009] However, such a prior art
In the automatic tracking device of
To increase the accuracy of the automatic phase search, run a magnetic tape
Reduce the amount of change in the row phase per cycle to reduce the tracking position.
The phases need to be changed slightly. But this
The tracking phase by slightly changing the tracking phase
Performing an automatic search of the switching phase results in the largest playback envelope
Number of tracking phase changes until
The number of steps is very large and the best tracking
It will take a long time to get the state. In particular, FIG.
At the point where the tracking phase at the start of the search is close to 0 °
When searching in the direction of the arrow from A, the maximum search time is
It costs. In this way, tracking search time becomes longer
Until a stable playback image is obtained after playback starts.
Disadvantage that the time (monitor cut time) in
is there. Also, as described above, the envelope level is
Search for an envelope phase that changes from increasing to decreasing.
Critical problems in the hill climbing method are as follows:
Occurs. First, the tracking position is actually
The regeneration envelope levels for the phases are shown in FIG.
Instead of being exactly sinusoidal, as shown in FIG.
When the tracking phase is close to (2n-1) π,
Work occurs. This means that the video head is
From the video head with the worst tracking condition
This is because noise is obtained. Like this
Of course, the playback envelope level naturally increases
Turned down, mislocked as best tracking and locked
However, a state where a reproduced image cannot be obtained is maintained. Second, tracking phase and reproduction envelope
As shown in FIG. 9 and FIG.
It is not decided intentionally. Tracking phase
Observing the playback envelope level at a constant
The playback envelope level varies greatly. This is
Due to fluctuations in the contact state between the video head and the magnetic tape
As a result of the actual measurement, as shown in FIG.
The raw envelope level has a fluctuation range indicated by diagonal lines.
You. Therefore, the tracking phase is set to t₁→ t_Two→ t_ThreeAnd change
In this case, as shown in FIG.
If the bell is sinusoidal, the playback envelope
Even though the level should decrease monotonically, the playback envelope
The loop level is c₁→ c_Two→ c_ThreeAnd c_TwoIs the peak
Tte_TwoTracking state with best tracking phase
Will be determined. Also, the tracking phase is t
_Four→ t_Five→ t₆The same is true when changing
Where the envelope level should increase monotonically, c_Five
Peaks and t_FiveBest tracking
It will be determined that the vehicle is in the locked state. As described above, the conventional hill-climbing method
Tracking devices can increase search time
However, there is a disadvantage that a malfunction occurs. When the tracking phase is changed
The rotation phase of the capstan motor,
It is difficult for the running phase of the
Will detect for the wrong playback envelope level.
There is a drawback that a search operation is performed. An object of the present invention is to eliminate the above disadvantages of the prior art.
Search time, greatly reducing the
Magnet with good tracking status
To provide an automatic tracking device for a recording / reproducing device.
And there. [0016] [MEANS FOR SOLVING THE PROBLEMS] To achieve the above object
In addition, the present invention provides a reference signal generating means, and a reference signal generating means.
Scans magnetic tape in synchronization with reference signal output from stage
Rotating head and signal delay means for delaying the reference signal
And a controller for reproducing a control signal on the magnetic tape.
A trawl head, the control signal and the signal delay
The output signal of the stage is input to control the capstan motor.
Phase comparison means that operates, and
The running speed of the magnetic tape is different from the standard recording / playback mode.
Long-time recording / playback mode
In a recording / reproducing device,The standard head is used as the rotating head.
Rotating head dedicated to recording / playback mode and the long-time recording / playback mode
With a dedicated rotating head, AndReproduction of the rotating head
Level detecting means for detecting an output level;
The delay time of the stage is variably controlled and detected by the level detecting means.
Delay of the signal delay means at which the reproduction output level becomes maximum
Time, and the delay time of the signal delay means is detected.
Delay control means for performing the operation of setting the delay time.Have
AndThe delay control means includes:During playback of the same magnetic tapeThe
Switching between the standard playback mode and the long playback mode
At this time, the signal delay means, as an initial delay time, the level
The reproducing output level of the rotary head detected by the detecting means is at a minimum.
Set a delay time near the large delay time.There
In addition, the delay control means may operate during reproduction of the same magnetic tape.
Between standard playback mode and long-time playback mode
At this time, the delay time of the signal delay means is set to a predetermined value.
Variable control again from the value. Furthermore, the present invention providesCon
Control signal and signal delay reproduced by the trawl head
Phase synchronization detection for detecting the phase relationship with the output signal of the extension means
Means, and said control means is provided by said phase synchronization detecting means.
The phase relationship between the signal and the output signal of the signal delay means is predetermined.
When it is detected that the stationary relationship
Means for variably controlling the delay time of the signal delay meansIn things
is there. [0017] [Action]During the playback operation, the delay control means
Variably controls the delay time of the reference signal of
So that the reproduced output level detected by the
By setting the delay time of the delay means,
Although the locking state can be obtained,The playback mode is
From the quasi-play mode to the long play mode,
When switching from raw mode to standard playback mode,So
Every timeThe above initial delay time by the signal delay meansAh
Or a predetermined valueIs set, sothis
After switching the playback modeThe playback output level quickly
Good tracking for maximumState is obtainedEspecially
You.The delay control means changes the delay time of the signal delay means.
And the reference signal from the signal delay means is reproduced.
The phase relationship with the tracking signal is out of the predetermined steady-state relationship.
After a finite period of time, a predetermined steady-state relationship is established again.
Before the steady relationship of the signal is restored again,
If you change the delay time of
Will be done. Therefore, the present invention
In addition, a phase synchronization detection means is provided to regulate the operation of the delay control means.
Control to reproduce the reference signal from the signal delay means.
The phase relationship with the tracking signal is a predetermined steady-state relationship.
Delay control means enables the delay time of the signal delay means before
Control without changing the phase of the reference signal.
Tracking operation can be prevented. [0018] BRIEF DESCRIPTION OF THE DRAWINGS FIG.
explain . FIG. 1 is a block diagram of a magnetic recording and reproducing apparatus according to the present invention.
FIG. 2 is a block diagram illustrating an embodiment of a smart tracking device.
Therefore, 1 is a magnetic tape, 2 is a capstan motor, 3 is
Cylinder motor, 4 for video head, 5 and 6 for phase comparison
Control means, 7 is a control head, 8 is an amplifier, 9 is
Reference signal generator, 10 is tracking mono multivibe
, 11 is a digital delay means, 12 is a delay control means.
Stage, 13 is an A / D converter, 14 is a sampling circuit, 1
5 is an amplifier, 16 is a rotational phase detector, and 17 is a waveform shaping circuit.
Path, 18 is delay circuit, 19 is sampling pulse generation
, 20 is a detection circuit, 21 is a sample and hold circuit, 4
4 is a phase synchronization detection circuit. Referring to FIG.
Representing the rotation phase of the cylinder motor 16
Is processed by the waveform shaping circuit 17 and the head switching signal HS
Is formed. This head switching signal HS is used for phase comparison control.
The reference signal R supplied to the means 5 and from the reference signal generator 9
The phase difference is compared with the EF and these phase difference signals are
Data 3. As a result, the cylinder motor 3
It rotates in phase synchronization with the reference signal REF. On the other hand, the computer recorded on the magnetic tape 1
The troll signal CTL is reproduced by the control head 7.
And amplified by the amplifier 8 and supplied to the phase comparison control means 6.
And the delay reference signal DREF from the digital delay means 11
The phases are compared. Phase difference signal from phase comparison control means 6
Is supplied to the capstan motor 2 and, as a result,
The stun motor 2 uses the control signal CTL and the delay reference
It is controlled and driven so that the signal DREF and the phase are synchronized.
You. Here, the delay reference signal DRE shown in FIG.
A method for forming F will be described. Reference signal RE generated by reference signal generator 9
The period of F is equal to the rotation period of the cylinder motor 3. this
Reference signal REF is tracking mono multivibrator
The time τ which is almost half of the period at 10₁Only delayed
Further, the digital signal is delayed by the digital
The signal DREF is formed. Delay of digital delay means 11
Time τ_TwoIs the best track by the delay control means 12.
It is set to be in the switching state. Generally, FIG.
As shown in the figure, the falling edge of the head switching signal HS
Digital delay so that the control signal CTL matches.
Delay time τ of the extension means 11_Two Is set. The best tracking state is realized.
Digital delay time τ_TwoAt the start of playback mode or
Playback when switching between raw mode and long playback mode
Detect the tracking phase at which the envelope level is maximum.
Determined by searching. This search first
By roughly changing the racking phase in the range of 2π,
Tracking for maximum playback envelope level
Detect the phase (coarse search), then
In the vicinity of the phase, the tracking phase is
Detect the tracking phase with the maximum envelope (fine
Search). This tracking phase change
Is controlled by the delay control means 12
Delay time τ_TwoCan be achieved by changing
Data for the tracking phase detected by the
Delay time τ of digital delay means 11_TwoBut the best tiger ahead
This is a delay time for realizing the locking state. Next, the delay time τ_TwoFor setting
The coarse search and the fine search will be described with reference to FIGS.
You. The reproduction signal from the video head 4 is an FM video
The reproduced signal FM is amplified by the amplifier 15.
And supplied to the sampling circuit 14. Waveform shaping circuit 1
7, the head switching signal HS obtained by the sampling circuit 1
4 is supplied. In the sampling circuit 14, the reproduction signal
The envelope of the signal FM is detected by the detection circuit 20,
This envelope voltage E is supplied to the sample and hold circuit 21.
Supplied. The head switching signal HS is supplied to the delay circuit 18
ヘ ッ ド period of the head switching signal
DHS is supplied to the sampling pulse generator 19 and
The sampling pulse SP is formed. Here, video
Head 4 has two heads, and a sampling pulse S
The timing of P is such that one of the heads is on the magnetic tape 1
Match the timing of playback scanning of the middle part of the track
I have. This sampling pulse SP is sample hold
The envelope voltage is supplied to the circuit 21 and the sample
Do it. Sampling of sample / hold circuit 21
The envelope voltage is supplied to the A / D converter 13.
The digital value is supplied to the delay control means 12. The delay control means 12 controls whether the magnetic recording / reproducing apparatus
When the playback mode is set, operation starts.
The coarse phase search is followed by the fine search.
You. In the coarse search, the digitized data is output from the A / D converter 13.
Sampling voltage (hereinafter simply referred to as sampling value)
) Is supplied, the delay control means 12 sets the digital delay.
Delay time τ of the extension means 11_TwoIs roughly changed. Therefore,
The delay reference signal DREF is output every rotation of the cylinder motor 3.
Sequentially τ_2-1, Τ_2-2, Τ_2-3, …… and delay time τ_TwoChanges
The tracking phase changes with this, and the reproduced signal
The envelope level of the FM changes. Digi at this time
Delay time τ of the total delay means 11_TwoIs the tracking phase
Changes by 2π (ie, one track pitch).
It is changed within the applicable range. At the same time, the delay control means 12
Is supplied with a sampling value from the A / D converter 13
For each sample, this sampled value and the sample
Compare with ring value, tracking phase changes by 2π
Digital delay for maximum sampling value in between
Stage 11 delay time τ_Two Is detected and held. FIG. 4 shows the digital delay in such a coarse search.
Delay time τ of the extension means 11_TwoPlay Envelope Pre
This shows the change in bell, and the tracking phase is 2
Delay time τ of digital delay means 11 for changing π
_TwoChange amount of T₀Then, in this coarse search, the delay control
Each time a sampling value is supplied to the means 12, a digital
The delay time of the delay means 11 is T₀Change by / 10
And Accordingly, the circles in FIG.
It shows the supplied sampling values. As described above, when the coarse search is completed,
A fine search is performed. This fine search is the most
Digital delay means 11 at large playback envelope level
Delay time τ_TwoA / D conversion within a predetermined range centered on
From the converter 13 to the delay control means 12
The delay time τ of the digital delay means 11_TwoI
Playback when changing by a predetermined range
Digital delay means 11 for maximizing the envelope level
Delay time τ_TwoAnd the delay time τ_Two
 But digital delay for best tracking
This is the delay time to be set in the means 11. Therefore, now, in FIG.
Digital delay means for maximum playback envelope level
11 delay time T₀/ 2 (Point B)
For a search, a delay of ± 1 step for coarser searches
2T₀/ 5 to 3T₀Digital delay means 1 up to / 5
1 delay time τ_TwoIn small increments (eg, T₀/ 100 without
Change). Then, in the delay control means 12, A /
Each time a sampling value is supplied from the D converter 13,
Sampling value and the sampling value supplied before it
By comparing the sampling value (and thus the playback
Delay time τ at which the envelope level) is maximized_Two Look for
Get out. As described above, first, a rough search is performed.
The maximum playback envelope level tracking phase
Search, and then the best tracking by fine search
To detect the tracking phase that causes the tracking state
Search for the tracking phase
And the accuracy of setting the best tracking conditions
Can be higher. In the case of the above example, ± T₀/ 20
0 precision, which is about ± 1.8 degrees. Also,
The problems described with reference to FIGS. 11 and 12 can also be solved,
Can be prevented. FIG. 5 shows one example of the digital delay means 11 in FIG.
FIG. 6 is a block diagram showing a specific example, and FIG.
22 is a waveform diagram, where 22 is a delay counter, and 23 is a matrix.
Circuit, 24 is a preset pulse generating circuit, 25 is
Gate, 26 is an inverter, 27 and 28 are input terminals
And 29 is an output terminal. 5 and 6, the input terminal 27
Is a tracking mono multivibrator 10 (FIG. 1)
Is supplied, and this output signal c is preset.
Digitally differentiated by the pulse generation circuit 24 and preset
A trigger pulse PS is formed. This is from input terminal 28
The rising edge of the output signal c of the supplied clock pulse CP
Extract the first pulse after
Luth PS. On the other hand, the delay counter 22 has a delay control
N-bit preset data from stage 12 (FIG. 1)
(D₁, D_Two, ……, D_n-1, D_n) (However, D_nIs the top
Bit) is supplied, and the preset pulse PS is delayed.
Each time it is supplied to the delay counter 22, the delay counter 22
The value of this preset data (hereinafter referred to as the preset value)
U) Preset to D. The matrix circuit 23
All bits Q of output value N of delay counter 22₁, Q_Two, ……,
Q_n-1, Q_nIs "1", this is detected and the output signal d
Is set to “L”, otherwise the level of the output signal d
Is set to “H”. Therefore, the delay is caused by the preset pulse PS.
When the counter 22 is preset, the matrix circuit
23 becomes "H" level, and the input terminal 28
Clock pulse CP is delayed through AND gate 25
The delay counter 22 supplies the
The lock pulse CP is counted. And delay counsel
All bits Q of the output value N of the₁~ Q_nIs "1"
Then, the output signal d becomes "L" and the AND gate
25 is turned off and the delay counter 22 counts.
Stop. The next preset pulse PS is a delay counter
22 and the delay counter 22 is preset.
And the output signal d of the matrix circuit 23 becomes “H”,
The delay counter 22 starts counting. Matrix times
The output signal d of the path 23 is inverted by the inverter 26,
From the terminal 29, the delay reference signal DREF
Supplied. Thus, the delay reference signal DREF
Is longer than the signal c from the input terminal 27 by the delay counter 22.
Has been preset, and all bits Q of the output value N₁~
Q_nOf the delay counter 22
When the preset value D changes, the delay reference signal D
REF delay time τ_TwoChanges. This delay time τ_TwoIs the delay counter 22
The preset value is M and the cycle of the clock signal CP is T_cpToss
Then, it is expressed by the following equation. [0043] (Equation 1) Therefore, changing the preset value M
The delay time τ_TwoChanges, and the delay reference signal DREF
And the tracking phase changes. This and
In both cases, as shown in FIG. 4, the playback envelope level
Changes. At the time of coarse search, the change of this preset value M
Change the preset value M for fine search.
After the best tracking phase is detected
Fixes the preset value M at that time. FIG. 7 shows a specific example of the delay control means 12 of FIG.
30 and 31 are input terminals, 3 and
2 is a counter means, 33 is a search speed setting circuit, and 34 is a search speed setting circuit.
Search end detection circuit, 35 is a data comparator, 36 is a memory
Stage, 37 and 38 are AND gates, 39 is a previous stage counter,
40 is a post-stage counter, 41 is an AND gate, 42 is a data counter.
And 43 is a counter memory. In FIG. 7, a clock is input from an input terminal 30.
The pulse φ receives the search start signal SS from the input terminal 31.
Are supplied respectively. This clock pulse φ
The cylinder mode is formed from the data switching signal HS (FIG. 1).
Has a period equal to the rotation period of the motor 3 (FIG. 1). Immediately
The reproduction envelope is obtained by the sampling circuit 14 (FIG. 1).
One input pulse for each level sampling
30 supplies a clock pulse φ. The counter 39 before and after the counting means 32
The stage counter 40 is a preset of the delay counter 22 of FIG.
Generates a default value D. The post-stage counter 40 uses this preset
Top D of values D_{m + 1}To D_nUp to (nm)
And the preceding stage counter 39 outputs the lower D₁To D_m
Generate m bits up to The post-stage counter 40 has an AND gate 38.
Clock pulse φ is supplied from the input terminal 30 through
However, this clock pulse φ is applied only to the post-stage counter 40.
Each time supplied, the preset value D is
Delay time τ of digital delay means 11 (FIG. 1)_TwoOne step
(Ie, as shown in FIG. 4)₀/ 10) change
Change by the value required for In addition, the former stage counter 39
Is supplied with the clock pulse φ via the AND gate 37
However, only this clock pulse
Each time φ is supplied, the preset value D is
Delay time of digital delay means 11 in one step
(In the above description, T₀/ 100) Value required to change
Only change. Next, the operation of this specific example will be described.
You. When the playback mode starts, or when
Switching between normal playback mode and normal playback mode
The search speed setting circuit 33 searches from the input terminal 31
The start signal SS is supplied, and the delay control means 12 operates.
To start. First, the first-stage counter 39 and the second-stage counter 4
Zero is reset to the value zero, and this zero value is
The search speed setting circuit 33 stores
The AND gate 37 is turned off, and the AND gate 38 is turned off.
Turn on. Also, search from the search speed setting circuit 33
A signal is sent to the end detection circuit 34 and the AND gate 41 is
Set to ON state. From this state the coarse search starts
You. The first signal supplied from the A / D converter 13
The sampling value is stored in the data memory 42. A / D
The next sampled value from the converter 13 is the data comparator 3
5 and stored in the data memory 42.
Value is compared to the At the same time, from the input terminal 30
The clock is supplied to the subsequent counter 40 via the AND gate 38.
One pulse φ is supplied and the value of the post-stage counter 40 is 1.
Increase. The sampler from the A / D converter 13
Sampling values stored in the data memory 42
If greater, the data comparator 35 issues a pulse.
This pulse is generated by the data
Are supplied to the memory 42 and the counter memory 43, and these are written.
Set to the writing state. As a result, the data memory 42
A / D converter 1 instead of previously stored sampling values
3 is stored in the counter memory 43.
Is the value of the post-stage counter 40 in place of the stored value of zero.
Store the value. Sampling value from A / D converter 13
Is the sampling value stored in the data memory 42.
If less than or equal to data
The memory 42 and the counter memory 43 are written.
The stored values are stored as they are
is there. As described above, the sump is sent from the A / D converter 13.
Each time a ring value is supplied, this sampled value is
Values and data stored in the data memory 42
The signals are compared by the comparator 35, and each time,
The clock pulse φ is supplied to the stage counter 40 one by one.
You. Then, the sampling value from the A / D converter 13 is
Larger than the sampling value stored in the data memory 42
Sampler stored in the data memory 42 only when
And the counter value is rewritten.
3 is also rewritten to the value of the latter-stage counter 40 at that time.
Therefore, the data memory 42 has been stored in the A / D converter
The largest of the sampling values supplied from 13
The ring value is always stored and stored in the counter memory 43.
Is supplied from the A / D converter 13.
The value of the post-stage counter 40 at the time of the occurrence is stored. Then, the tracking phase changes by 2π
The digital delay as shown in FIG.
The delay time of the means 11 is 0 to T₀When changed to
Search ends. The data memory 42 has the coarse detection
The maximum sampling value obtained by the search is stored,
The counter memory 43 stores this sampling value in the A / D
The value of the post-stage counter 40 when supplied from the converter 13
Is stored. This value is the value of point B in FIG.
You. The end of the coarse search is determined by the search speed setting.
After the search start signal SS is supplied by the circuit 33, the clock
Is detected by counting a predetermined number of
Is transmitted to the search end detection circuit 34. Also,
At the same time, the AND gate 38 is turned off. Search
Under the control of the end detection circuit 34, the counter memory 43
Is read out, and 1 is subtracted from this value.
The value thus set is set in the post-stage counter 40. Thus, later
When a value is set in the stage counter 40, the preceding stage counter 39
And the value D obtained by the post-stage counter 40 are digital delay means.
11 shows the delay time 2T at point A in FIG.₀/ 5 was set
become. Next, the value of the preceding stage counter 39 is zero.
Rewritten in the memory 43 and the AND gate 37 is turned on
Then, a detailed search is started. This fine search
Means that the clock pulse φ
D is supplied to the counter 39 and the D₁,
D_Two, ……, D_mThe value consisting of bits changes,
In the memory 43, as described above, the data comparator 35
According to the comparison result of
At the time of coarse search other than rewriting to the value of the stage counter 39
The operation is the same as that described above. In this case, the value of the post-stage counter 40 is fixed.
As a result, only the value of the pre-stage counter 39 changes, and
And the value D obtained by the latter-stage counter 40 and the former-stage counter 39
Is supplied with a clock pulse φ to the preceding stage counter 39.
Each time, it changes by a finer value than in the coarse search, where
Means that the delay time of the digital delay means 11 is T₀/ 100 without
The value D changes in such a manner as to change. This fine search is performed by using a digital
The delay time of the delay means 11 is T₀/ 2 ± T₀/ 10 range
Enclosure, ie 2T₀/ 5 (point A) to 3T₀/ 5 (point C)
Is done to change the range at which the maximum
Is stored in the data memory 42.
When the sampling value is supplied from the A / D converter 13
Is stored in the counter memory 43.
It is. When the detailed search is completed, the AND gate 3
7 is turned off, and the search end detection circuit 34 operates.
And the AND gate 41 is turned off, and
The stage counter 39 is held in the counter memory 43
Rewritten with the value. As a result of the above search, the former-stage counter 39 and the latter-stage counter
When the value of the stage counter 40 is set, respectively,
According to the value D, the delay time of the digital delay means 11 is reproduced.
The envelope level of the signal FM (Fig. 1) will be maximum
Is set as follows. In the above embodiment, as shown in FIG.
For convenience of explanation, the playback envelope level is at the minimum.
From the state, rough search was started, but tracking
By appropriately setting the time constant of Gumono Multi 10,
As shown in FIG. 8, a reproduction envelope level is obtained.
Nearby (for example, a track where the maximum envelope level is obtained)
(Within ± 90 ° of the locking phase)
You can start a coarse search, but rather
Good. This is, as is clear from FIG.
By the end of the search, the playback envelope level is high and compared
Good tracking, low noise ratio
Reproduced images of relatively good image quality have been obtained.
Degradation of playback quality is almost apparent even after moving to search
Search is performed in a direction to further improve the playback image quality.
You. Therefore, if the search time is shorter than the actual time
There is an advantage that it is. Further, as shown in FIG.
1 second from point B where a large playback envelope level is obtained
The coarse search is started from the state of point A before the step.
The coarse search is approximately equal to the state of point A
Since the processing ends at the point A ', the subsequent stage counter 40 (FIG.
In 7), the value at the end of the coarse search is held as it is.
You can move on to the fine search, and count
Of values from the data memory 43 (FIG. 7) to the post-stage counter 40.
No replacement is required. Therefore, as shown in FIG.
Compared to performing a coarse search,
Not only does it seem short, but the actual search time
Be shortened. Also, in this case, the
And writes the value of the latter-stage counter 40 to the data memory 43.
Therefore, the circuit configuration of the delay control means 12 is
Simplified. Further, the delay control means 1 shown in FIG.
In FIG. 2, during the coarse search period, the AND gate 38 is
During the search period, the AND gate 37 is kept in the ON state.
But the timing of the comparison operation of the data comparator 35
Clock pulse φ from input terminal 30
Data comparison by setting the relationship with
Each time the detector 35 compares the two sampled values, the data ratio
A signal is sent from the comparator 35 to the search speed setting circuit 33,
At the time of search, the data comparator 35 outputs two sampling values.
Each time is compared, the AND gate 38 is turned on for a certain period of time.
State, and when searching fine, similarly AND gate
37 is turned on for a fixed period, and the input terminal 30
During a period substantially equal to the period during which the clock signal φ is supplied.
Only, the AND gates 38 and 37 can be turned on.
Wear. As a result, the rear-stage counter 40 and the front-stage counter 3
9 from being supplied with undesired noise pulses.
Can be. Here, at the time of a coarse search, the reference signal REF
Each time the digital delay means 11 delays, the capstan
The rotational phase of the motor 2, that is, the running phase of the magnetic tape 1 is instantaneously changed.
Intermittently follows the phase of the delay reference signal DREF
Explained. However, the phase of the delay reference signal DREF changes.
From this point, the phase of the delay reference signal DREF and
Until the running phase of the magnetic tape 1 becomes a predetermined stationary relation.
Has a finite time. This time
There is no problem if it is sufficiently shorter than the rotation cycle of motor 3.
Is approximately equal to or greater than this rotation period.
Sometimes. Within such time, the delay control means 12
When performing a coarse search operation, an incorrect playback envelope
This means that a search operation has been performed for the file. The problem is that the running speed of the magnetic tape 1 is
At the time of searching in the slow triple speed playback mode or digital delay means 1
1 delay time τ_TwoSuch as when performing a fine search with small changes in
The traveling amount of the magnetic tape 1 per rotation of the cylinder motor 3 is
If the number is small, there is no problem.
During coarse search in standard playback mode with fast line speed
Can be a problem. As a means for solving such a problem, phase synchronization
A detection means 44 is provided, and a control signal from the amplifier 8 is provided.
CTL and delay reference signal DR from digital delay means 11
The phase relationship with EF is detected, and this phase relationship is determined to be a predetermined steady state.
When there is no relevance, the search operation by the delay control
Pause the work, and it is this predetermined steady relationship
Then, the search operation is performed again. Therefore, when searching, the delay control means 12
The delay time τ of the digital delay means 11_TwoChanges,
Phase correlation between troll signal CTL and delay reference signal DREF
If the engagement deviates from the predetermined steady-state relationship, the search operation temporarily stops.
During which the delay time τ of the digital delay means 11_Two
Is kept as it is. After that, the above phase relationship is determined
Is reached, the phase synchronization detecting means 44 detects this.
And the delay control means 12 starts the search operation to
Delay time τ of delay means 11_Two To change. The delay due to the output signal of the phase synchronization detecting means 44
The control of the operation and non-operation of the extension control means 12 is as follows.
Done. That is, in FIG.
If so, the AND gate 38 is turned on.
And the data comparator 35 is in the comparison operation state,
Control signal CTL and delay reference
The phase relationship with the signal DREF deviates from the predetermined steady-state relationship.
Is detected, the output of the phase synchronization detecting means 44 is
The force signal is supplied to the data comparator 35 and the data comparator 3
5 is stopped. At the same time, the data comparator 35
Sends a command signal to the search speed setting circuit 33.
As a result, the AND gate 38 is turned off. By this
As a result, the delay control means 12 is stopped, and
Refuse. Next, the phase synchronization detecting circuit 44
The phase relationship between the delay signal CTL and the delay reference signal DREF is
When it is detected that the
In accordance with the output signal of the phase synchronization detection circuit 44, a data comparator
At 35, the stop state is released, and the search speed is set accordingly.
The setting circuit 33 turns on the AND gate 38. this
As a result, the delay control means 12 restarts the search operation. The phase synchronization detecting means 44 is
Problem with coarse search in standard playback mode
However, when performing a fine search or a 3x playback mode
If the same problem occurs when searching in the network
It goes without saying that this will be resolved,
And the control signal CT
Running state of magnetic tape becomes unstable due to lack of L etc.
In such a case, the search operation stops during this period and the search results
Is not affected. [0072] As described above, according to the present invention,
In standard playback mode or long playback mode,Best
Tracking status that can get racking status
It can be set reliably and with high accuracy,Again
The raw mode changes from the standard playback mode to the long playback mode,
Switch from the long playback mode to the standard playback mode
Sometimes, each time the switch is made, the signal delay means
Time or a predetermined delay time
So, the best from this switching of the playback mode
Set the tracking phase to obtain the tracking state of
Time can be shortened sufficiently,
Good tracking state where the playback output level is maximized
And switching between the playback modes.
Can greatly reduce monitor cut time
it can. Further, according to the present invention, the phase synchronization detecting means
Control signal to be reproduced and output of signal delay means
Detects that the relationship with the signal has reached a predetermined stationary relationship
The delay control means adjusts the delay time of the signal delay means.
Since these are variably controlled, these phases
After the relationship is stabilized to the predetermined steady-state relationship, the delay control means
Variable delay time control of the next signal delay means is performed by
And prevent false tracking behavior.
Can be.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing one embodiment of an automatic tracking device of a magnetic recording / reproducing device according to the present invention. FIG. 2 is an explanatory diagram showing a phase of a reference signal for controlling a rotation phase of the capstan motor of FIG. 1; FIG. 3 is a waveform chart showing signals of respective units at the time of a search operation in FIG. 1; FIG. 4 is a graph showing an example of a relationship between a delay time of a digital delay unit and a reproduction envelope level during a search operation in FIG. 1; FIG. 5 is a block diagram showing a specific example of a digital delay unit in FIG. 1; FIG. 6 is a waveform chart showing signals of respective parts in FIG. FIG. 7 is a block diagram showing a specific example of the delay control means of FIG. 1; FIG. 8 is a graph showing a relationship between a delay time of a digital delay unit and a reproduction envelope level at the time of the search operation in FIG. 1; FIG. 9 is a characteristic diagram showing a relationship between a tracking phase and a reproduction envelope level. FIG. 10 is an explanatory diagram showing a change in a sampling value with respect to a change in a reproduction envelope level. FIG. 11 is an explanatory diagram showing an example of a malfunction in a tracking phase search in an automatic tracking device of a conventional magnetic recording / reproducing device. FIG. 12 is an explanatory diagram showing another example of a malfunction in tracking phase search in an automatic tracking device of a conventional magnetic recording / reproducing device. DESCRIPTION OF SYMBOLS 1 Magnetic tape 2 Capstan motor 4 Video head 6 Phase comparison means 7 Control head 9 Reference signal generator 10 Tracking monaural multivibrator 11 Digital delay means 12 Delay control means 13 A / D converter 14 Sampling circuit 30 Clock pulse input terminal 31 Search start signal input terminal 32 Counter means 33 Search speed setting circuit 35 Data comparator 36 Memory means 39 Pre-stage counter 40 Post-stage counter 42 Data memory 43 Counter memory 44 Phase synchronization detection circuit

Continued on the front page (72) Inventor Shuko Okamoto 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside Hitachi, Ltd. Home Appliances Research Laboratory (72) Inventor Yasuo Fukushima 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Hitachi, Ltd. In the laboratory (72) Inventor Katsuhiko Goto 1410 Inada, Katsuta, Ibaraki Pref.Hitachi, Ltd.Tokai Plant (72) Inventor Takashi Takahashi 1479, Josuihoncho, Kodaira, Tokyo Co., Ltd.Hitachi Microcomputer Engineering Co., Ltd. In-company (56) References JP-A-58-1843 (JP, A) (58) Fields studied (Int. Cl. ⁶ , DB name) G11B 15/467

Claims (1)

(57) [Claims] A reference signal generating means, a rotary head for scanning the magnetic tape in synchronization with the reference signal output from the reference signal generating means, a signal delay means for delaying the reference signal, and reproducing a control signal on the magnetic tape And a phase comparison means for inputting the control signal and the output signal of the signal delay means to control and drive the capstan motor. In a magnetic recording / reproducing apparatus capable of setting a long recording / reproducing mode in which a running speed of a tape is different , a rotation dedicated to the standard recording / reproducing mode is used as the rotating head.
Head and a rotary head dedicated to the long-time recording / reproducing mode.
Provided, and level detecting means for detecting the reproduced output level of the rotary head, the reproduction output level detected by the said level detecting means a delay time of the signal delay means variably controlled to the of the signal delay means having a maximum Delay control means for detecting a delay time and setting the delay time of the signal delay means to the detected delay time , wherein the delay control means controls the standard time during reproduction of the same magnetic tape. When switching between the reproduction mode and the long-time reproduction mode, the signal delay means is provided with an initial delay time in the vicinity of the delay time at which the reproduction output level of the rotary head detected by the level detection means becomes maximum. An automatic tracking device for a magnetic recording / reproducing device, wherein a time is set. 2. Reference signal generating means, and output from the reference signal generating means
Rotation to scan the magnetic tape in synchronization with the reference signal
A signal delay means for delaying the reference signal;
To the control that reproduces the control signal on the tape
And the control signal and the output signal of the signal delay means.
And the phase to control and drive the capstan motor
Comparing means, a standard recording / reproducing mode and a standard recording / reproducing mode.
A long time recording in which the running speed of the magnetic tape is different from the raw mode
Magnetic recording / reproducing device that can set recording / reproducing mode
In this case, as the rotating head, a rotation dedicated to the standard recording / reproduction mode is used.
Head and a rotary head dedicated to the long-time recording / reproducing mode.
Provided, and level detection for detecting the reproduced output level of said rotary head
Means out, the level detected by variably controlling the delay time of the signal delay means
The signal delay at which the reproduction output level detected by the means is maximum.
The delay time of the signal delay means is detected.
Control means for performing an operation with the detected delay time
Has bets, said delay control means, the standard in the reproduction of the same magnetic tape
When switching between the play mode and the long play mode,
The delay time of the signal delay means is determined from a predetermined value.
Of the magnetic recording / reproducing apparatus characterized by performing variable control again.
Auto tracking device. 3. Reference signal generating means, and output from the reference signal generating means
Rotation to scan the magnetic tape in synchronization with the reference signal
A signal delay means for delaying the reference signal;
To the control that reproduces the control signal on the tape
And the control signal and the output signal of the signal delay means.
And the phase to control and drive the capstan motor
Comparing means, a standard recording / reproducing mode and a standard recording / reproducing mode.
A long time recording in which the running speed of the magnetic tape is different from the raw mode
Magnetic recording / reproducing device that can set recording / reproducing mode
In this case, as the rotating head, a rotation dedicated to the standard recording / reproduction mode is used.
Head and a rotary head dedicated to the long-time recording / reproducing mode.
Provided, and level detection for detecting the reproduced output level of said rotary head
Means out, the level detected by variably controlling the delay time of the signal delay means
The signal delay at which the reproduction output level detected by the means is maximum.
The delay time of the signal delay means is detected.
Control means for performing an operation with the detected delay time
And the control signal reproduced by the control head
For detecting the phase relationship between the signal and the output signal of the signal delay means.
Phase delay detection means , wherein the delay control means is provided with the standard
When switching between the play mode and the long play mode,
In the signal delay means, the level detection means is used as an initial delay time.
The playback output level of the rotary head detected by the step becomes the maximum.
A delay time near the delay time is set , and the control signal and the signal are detected by the phase synchronization detecting means.
Phase relationship with the output signal of the signal delay means
When the delay control means detects that
A magnetic device characterized in that the delay time of the delay means is variably controlled.
Auto-tracking device for energy recording and playback devices.