JP3132362B2 - Auto tracking device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic tracking device for a magnetic recording / reproducing apparatus capable of performing noiseless reproduction even at non-integer multiple speed reproduction.

[0002]

2. Description of the Related Art As a conventional auto tracking device, one described in Japanese Patent Publication No. 6-30195 is known. This apparatus divides the reproduction output of one field into three areas of a front part, a center part, and a rear part, samples a plurality of reproduction outputs of each area, and compares the total sum of the sampled data for each area. It is intended to obtain a tracking state.

[0003]

However, in the conventional apparatus, an optimum tracking state is obtained by using only information obtained from one-field reproduction output.
It is not possible to cope with a reproduction speed in which one repetitive pattern is formed in six fields such as 1.33 speed reproduction. In other words, this apparatus can cope with only the case where the reproduction envelope waveform for each field is the same, such as double speed and still reproduction. Further, a plurality of samplings are required in each area, and an operation for calculating the sum is required. Assuming that the processing is performed using a processor or the like, the processing time increases.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems. By comparing the output at the both ends and the middle point of the continuous reproduction output by the long-time reproducing head, the reproduction output from the continuous plural tracks is compared. It is an object of the present invention to provide an automatic tracking device capable of obtaining an optimal tracking state.

[0005]

In order to achieve this object, according to the present invention, when non-integer multiple speed reproduction such as 1.33 double speed reproduction is performed, continuous reproduction output from a long-time reproduction head is detected by a detection means. The detection and the filtering are further performed by a filter means, and the outputs near the both ends and the middle point are taken in as digital data by the sampling means to obtain an optimum tracking state by comparing three points.

As a result, a reproduced image without noise can be obtained even at non-integer multiple speed reproduction.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS first aspect of the present invention includes a capstan motor for transferring at different constant speed and the tape speed during recording a magnetic recording tape, generating a phase control reference signal of the capstan motor Reference signal generating means, a phase control means for controlling the phase of a capstan motor based on a reproduction control signal reproduced from the magnetic recording tape and the reference signal, and a cylinder motor having a plurality of heads for reproducing a video signal; Detecting means for detecting the reproduced output of the head; filter means for filtering the output of the detecting means; sampling means for sampling three specific points of the output of the filter means; Comparing means for comparing sampling data at a point, and the reference signal or the The delay control means delays the reproduction control signal. The optimum tracking is achieved by sequentially changing the delay amount of the delay means based on the result of comparison of the data at three specific points of the output obtained by the detection means. Get.

According to a second aspect of the present invention, there is provided a capstan motor for transferring a magnetic recording tape at a constant speed different from the tape speed at the time of recording, a reference signal generating means for generating a phase control reference signal for the capstan motor, and Phase control means for controlling the phase of a capstan motor by a reproduction control signal reproduced from a magnetic recording tape and the reference signal, a cylinder motor having a plurality of heads for reproducing a video signal, and a reproduction output of the heads Extracting means for extracting adjacent crosstalk components; sampling means for sampling two specific points of the output of the extracting means; comparing means for comparing sampling data at two points obtained by the sampling means; Delay means for delaying the reference signal or the reproduction control signal based on the result of comparison by the comparing means In this configuration, optimal tracking is obtained by sequentially changing the amount of delay in the delay means based on the result of comparison of sampling data of two adjacent crosstalk components.

According to a third aspect of the present invention, there is provided a capstan motor for transporting a magnetic recording tape at a constant speed different from the tape speed at the time of recording, a cylinder motor having a plurality of heads for reproducing video signals, Detecting means for detecting the reproduced output; sampling means for sampling two specific points of the output of the detecting means; and a value obtained by multiplying a difference value of the sampling data at the two points obtained by the sampling means by a predetermined gain. Phase control means for performing feedback control of the capstan motor based on the above, obtains capstan phase information by sampling two specific points from the output of the detection means, and The phase control is performed by feeding back as a phase error.

An embodiment of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1 shows a configuration of an automatic tracking apparatus according to Embodiment 1 of the present invention, wherein 1 is a capstan motor for driving a magnetic recording tape 5 at a constant speed, and 2 is a rotational speed of the capstan motor. 3 is a capstan servo circuit for controlling the speed and phase of the capstan motor 1, 4 is a control head for detecting a control signal reproduced from the magnetic recording tape 5, 6 is an image on the magnetic recording tape 5 A cylinder motor having a head for recording and reproducing signals, a frequency generator 7 for detecting the rotation speed of the cylinder motor 6, a cylinder servo circuit 8 for controlling the rotation of the cylinder motor 6, 9
a and 9b are switching circuits for selecting and switching the head, 10 is a detection circuit for detecting a reproduced output signal,
Reference numeral 11 denotes a low-pass filter (hereinafter, referred to as LPF) for filtering the output of the detection circuit 10, reference numeral 12 denotes an AD converter for sampling the output of the LPF 11, reference numeral 13 supplies three points of sampling data from the AD converter 12, A comparator that supplies a delayed signal based on the comparison result to the monomulti 14,
Reference numeral 14 denotes a head switching signal (H
A mono-multi 15 whose delay amount changes from the SW signal) is a timing at which a sampling signal is supplied to the AD converter 12 based on two head switching signals (HSW signal and HASW signal) supplied from the cylinder servo circuit 8. Generator.

The capstan servo circuit 3 has a capstan FG signal (CFG) output from the frequency generator 2.
Signal), a control signal (CTL signal), which is an output of the control head, and an output of the mono-multi 14. A frequency generator 7 is provided to the cylinder servo circuit 8.
, And a cylinder PFG signal obtained by mixing the cylinder FG signal and the cylinder PG signal, and the HSW signal and the HASW signal generated based on the cylinder PFG signal are supplied to the switching circuit 9. The processing in the cylinder servo circuit 8, the comparator 13, the mono multi 14, the capstan servo circuit 3, and the timing generator 15 are all realized by using the arithmetic and logical operation functions of the microprocessor.

The operation of the auto-tracking device having the above-described configuration at 1.33 times speed reproduction in the standard mode will be described below with reference to FIGS. Cylinder motor 6
Is determined by the cylinder servo circuit 8 based on the PFG signal.
The constant speed rotation is controlled at a rotation speed substantially equal to the double speed. The reproduced output from the head is supplied to switching circuits 9a and 9b, and the switching circuits 9a and 9b include a cylinder servo circuit 8
HSW signal and HASW signal are supplied from
A standard reproducing head (R ′ head, L ′ head) and a long-time reproducing head (R head, L head) are selected and switched for each field by a combination of two signal logics. Note that the track width of the long-time reproducing head is a narrower head than the standard reproducing head.

At 1.33 × speed, the R head, L head, R head,
The R 'head, L' head, and R 'head are selected, and the reproduction output changes every six fields. The waveform is a waveform composed of peaks and valleys every three fields, like the reproduction envelope signal a shown in FIG. The playback envelope signal a is
The reproduction envelope waveform is input to the detection circuit 10 and detected, and a detection output b is obtained. The detection output b is further supplied to a low-pass filter 11 to remove a noise component, and becomes an LPF output c.
The voltage value at the point is captured as a digital value.

Here, setting of three sampling points (p point, q point, r point) will be described with reference to FIG. Originally, if there was no LPF 11, the detection output b would be
The sampling may be performed by the converter 12. However, the detection output b contains a large amount of high-frequency noise components, and if this output is sampled as it is, the originally required reproduction envelope a cannot be correctly detected. Therefore,
The LPF 11 removes noise, but if filtering is performed, a time lag occurs between the detection output b and the LPF output c. As a result, the point p and the point q are originally located symmetrically, but the position of the point p is shifted rightward as shown in FIG. That is, first
The q point is set near the end point of the field, and the LP at that time
The F output c is set to β [V]. Next, a point having the same potential as the point q is defined as a point p. The r point is a midpoint between the p point and the q point.

From the timing generator 15, this p point,
The sampling signal d is supplied to the AD converter 12 at timings t1, t2, and t3 as times from the start point of the first field corresponding to the points q and r. As a result, AD
In the converter 12, the voltage values α [V], β at the p, q, and r points
[V] and γ [V] are captured as digital values. FIG.
Is 3 of tracking error and detection output (LPF output c)
It shows the relationship between voltages at points (p point, q point, r point). Region I represents the case where the amount of tracking deviation from the tracking center is small.
(Α <γ, β <γ). Furthermore, α and β
Is centered when is approximately equal. Regions II and III are cases where the tracking deviation amount is large. In this case, (α <γ) or (β>
γ). Therefore, if the magnitude relationship between α, β, and γ is determined, the current tracking state can be determined, and furthermore, the region I
, It can be seen that if the tracking is shifted so that the difference between α and β becomes smaller, the tracking becomes the center.

FIG. 4 is a flowchart when the processing in the comparator 13 is realized by software. In the branch 20, it is determined whether or not it is the data fetch timing.
Where sampling data (α,
β, γ) is taken up. If not, the process returns to the branch 20 again. In branch 22, α
And γ are compared. If (α> γ), the maximum delay amount in the forward direction is set by the block 23, and the process proceeds to the branch 30. If not (α> γ), the process proceeds to the branch 24, where β and γ are compared. If (β> γ), the maximum delay amount in the negative direction is set by the block 25, and the process proceeds to the branch 30.
If (β> γ), the process proceeds to the branch 26. Branch 2
At 6, it is determined whether or not the absolute value of the difference between α and β is greater than a predetermined value ε.
If it is smaller, the process ends. In branch 27, α
When α is larger, the block 29 sets a delay amount one smaller than the current delay amount, and proceeds to the branch 30. If β is larger, the block 28 sets a delay amount one greater than the current delay amount, and proceeds to branch 30. In the branch 30, it is determined whether or not a predetermined time required for the capstan to perform phase lock has elapsed, and if it has elapsed, the process returns to the block 20 again. If not, the process returns to the input of the block 30 and waits for a time.

By the above series of processing, the set delay amount is output from the comparator 13. The mono multi 14 changes the delay amount of the mono multi 14 based on the delay output. A signal delayed by a predetermined amount from the HSW signal is output from the mono multi 14 and supplied to the capstan servo circuit 3. In the capstan servo circuit 3, the delayed H
Auto tracking is performed by performing phase control based on the phase difference between the SW signal and the CTL signal. As a result, when in the region II of FIG.
, The tracking is transferred to the region I when it is within the region I and further to the center position of the region I when it is within the region I.

By the repetitive operation described above, tracking finally becomes α [V] ≒ β [V], and an optimum tracking state is obtained. As described above, according to the auto-tracking apparatus of the present invention, auto-tracking at a non-integer multiple speed can be performed using only appropriate sampling data at three points without changing hardware.

(Embodiment 2) Hereinafter, Embodiment 2 of the present invention will be described with reference to FIG. The parts having the same functions as those in FIG. 1 are denoted by the same reference numerals. In FIG. 5, 16 is a reproduced video signal processing circuit, 19 is a crosstalk extraction circuit, and the reproduced video signal processing circuit 16 is a preprocessing unit 17 (not shown as preprocessing in the figure) and a PS process for removing adjacent crosstalk. It comprises a circuit 18 (abbreviated as PS processing in the figure). In the pre-processing unit 17, a series of pre-processing such as reproduction pre-amplification for amplifying the output from the head, a low-pass filter, and frequency conversion is performed.

The PS processing circuit 18 is a VHS (registered trademark)
This is used in the color signal processing section of the VTR system to remove adjacent crosstalk.
A signal obtained by rotating the phase by degrees, recording the data by changing the direction of rotation for each track, and reversing the phase every 1H with respect to the recording time by a phase correction circuit at the time of reproduction and restoring it to a normal low-frequency converted color signal Has been entered.

The operation of the PS processing circuit 18 and the crosstalk extraction circuit 19 will be described below with reference to FIGS. P
The S processing circuit 18 adds the original signal and a signal obtained by delaying the original signal by 1H (H is one horizontal synchronization cycle). The original signal a and the signal b separated by 1H from the original signal a have the adjacent crotalk components in the chrominance signal having phases opposite to each other.
In the component in b), the main signal component is doubled, the adjacent crosstalk component is canceled and becomes zero, unnecessary adjacent components are removed, and the component is output from the output terminal 1.

On the other hand, an original signal a and a signal b obtained by delaying the original signal a by 1H are supplied to a subtraction point of the crosstalk extracting circuit 19, and a signal b delayed by 1H is subtracted from the original signal a. Accordingly, the main components are canceled to be zero, and conversely, the adjacent crosstalk component is doubled and output. At this time, the phase of the crosstalk component for each 1H is inverted. A horizontal synchronizing signal (Hsync) is input to an input terminal 2 and is divided by a frequency divider by a factor of two. The signal after frequency division is input to the switching circuit (the switch in the figure) as a switching signal, and the output signal of the subtraction point and the signal whose polarity is inverted are the rising edge of the signal obtained by dividing Hsync by two. , At the timing of the falling edge. That is, a signal before the polarity inversion and a signal whose polarity is inverted are alternately selected and output for each horizontal synchronization signal. Thus, the crosstalk component having the same polarity is always output from the crosstalk extraction circuit 19.

The output of the crosstalk extraction circuit 19 is sampled by the AD converter 12. The sampling timing at this time is the same as in the first embodiment. Further, the subsequent processing by the comparator 13 is performed in the same manner as in the first embodiment. As described above, according to the auto tracking apparatus of the present invention, the crosstalk extraction circuit 19 is used by using the input of the existing PS processing circuit 18 and the output delayed by one horizontal synchronization period.
Thus, adjacent crosstalk components can be easily extracted. Further, it is possible to perform auto-tracking with higher accuracy than the method according to the first embodiment for detecting the reproduction envelope of the main signal.

(Embodiment 3) Hereinafter, Embodiment 3 of the present invention will be described with reference to FIG. 20 is A
A subtractor 21 calculates the difference between the two points of sampling data supplied from the D converter 12, and a multiplier 21 multiplies the output of the subtractor by a constant k. Regarding the auto tracking device configured as above, 1.
A description will be given of 33 × speed reproduction as an example.

The AD converter 12 supplies sampling data (α, β) at points p and q in FIG. In the subtracter 20, β is subtracted from α, and the subtraction result is supplied to the multiplier 21. In the multiplier 21, the input data is multiplied by a constant k sufficiently smaller than 1, and the result of the multiplication is input to the capstan servo circuit 3. The constant k is
An appropriate predetermined value is set depending on the tape feed speed and the head amplifier output. In the capstan servo circuit 3, speed control is performed based on the capstan FG signal (CFG), and the magnetic tape 5 is transported at a constant speed of 1.33 times. The result of the multiplication is added as a phase error to the speed error of the speed control loop, and after a predetermined gain correction, it is DA-converted and a control voltage is supplied to the motor driver to control the rotation of the capstan motor 1. . That is, phase control is performed by detecting a phase error from two points of on-track information obtained from the reproduction envelope and forming a feedback control loop so that the detection error becomes zero. When the output of the subtractor 20 becomes substantially zero, the tracking deviation amount becomes zero, and an optimum tracking state is obtained.

As described above, according to the automatic tracking apparatus of the present invention, an optimum tracking state can be obtained without using a CTL signal. Therefore, the CTL head, the CTL amplifier, and the phase reference generator, which are conventionally required, are not required, and the system is greatly simplified. Also,
Since tracking control is performed using existing hardware, there is no increase in cost.

In the first and second embodiments, the reference signal supplied to the capstan servo circuit 3 is a signal obtained by delaying the HSW signal output from the cylinder servo circuit 6, but the present invention is not limited to this. Instead, for example, an internal reference signal synchronized with an HSW signal created in the cylinder servo circuit 8 may be used. It is obvious that the CTL signal may be delayed instead of delaying the reference signal.

Further, in the third embodiment, the description has been given of the 1.33 × speed reproduction. However, for example, in the 0.75 × speed reproduction which is slower than the 1 × speed, the subtraction direction in the subtracter 20 is changed from (α−β) to (β−α). It is obvious that this can be realized only by changing to.

[0029]

As described above, according to the first aspect of the present invention, good noiseless reproduction can be performed even in the case of reproduction of a compatible tape with a shifted X value, and two appropriate points can be obtained without changing hardware. Auto-tracking at non-integer multiple speeds such as 1.33x speed and 0.75x speed is possible using only the sampling data. In addition, it is possible to reduce noise even if the processing shifts to the next speed without waiting for the end of the auto tracking in the 1 × speed reproduction.

Further, in the second invention, in addition to the effects of the above invention, it is possible to perform tracking control with higher accuracy. In addition, since the hardware configuration uses an existing circuit, a simple configuration can be used. In the third aspect, an optimum tracking state can be obtained without using a CTL signal. In addition, a delay circuit and a feedback loop of a CTL signal are unnecessary,
The circuit configuration is simplified. Furthermore, since tracking control is performed using existing hardware, there is no increase in cost.

[Brief description of the drawings]

FIG. 1 is a block diagram of an auto tracking device according to a first embodiment of the present invention.

FIG. 2 is a signal waveform diagram of each part of the device.

FIG. 3 is a characteristic diagram showing a relationship between a tracking shift and a detection output in the apparatus.

FIG. 4 is a flowchart showing the operation of the comparator of the apparatus.

FIG. 5 is a block diagram of an auto tracking device according to a second embodiment of the present invention.

FIG. 6 is a block diagram of a PS processing circuit and a crosstalk extraction circuit of the device.

FIG. 7 is a diagram illustrating the principle of color signal processing performed by the apparatus.

FIG. 8 is a block diagram of an auto tracking device according to a third embodiment of the present invention.

[Explanation of symbols]

 1 Capstan motor 3 Capstan servo circuit 6 Cylinder motor 8 Cylinder servo circuit 9 Switching circuit 15 Timing generator

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-67456 (JP, A) JP-A-3-205640 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G11B 15/467 H04N 5/783

Claims (6)

(57) [Claims] 1. A capstan motor for transporting a magnetic recording tape at a constant speed that is a non-integer multiple different from the tape speed at the time of recording; a reference signal generating means for generating a phase control reference signal for the capstan motor; A phase control means for controlling the phase of a capstan motor by a reproduction control signal reproduced from a magnetic recording tape and the reference signal, a cylinder motor having two pairs of heads having different azimuth angles and reproducing a video signal, Detecting means for detecting the reproduction output of the head; low-pass filter for filtering the output of the detecting means; sampling means for sampling three specific points of the output of the low-pass filter; three points obtained by the sampling means Comparing means for comparing the sampled data at Auto-tracking apparatus characterized by comprising a delay means for delaying the reference signal or the reproduction control signal. 2. A capstan motor for transporting a magnetic recording tape at a constant speed which is a non-integer multiple different from the tape speed during recording, and a cylinder having two pairs of heads having different azimuth angles for reproducing video signals. A motor, a detecting unit for detecting a reproduction output of the head, a low-pass filter for filtering an output of the detecting unit, a sampling unit for sampling two specific points of the output of the low-pass filter, and the sampling unit. An automatic tracking device comprising: a phase control unit that performs feedback control of the capstan motor based on a value obtained by multiplying a difference value between the two points by a predetermined gain. 3. A head that reproduces a video signal has two azimuth angles different from each other and is located at a position facing 180 degrees, and two heads located at a position facing 180 degrees apart from the head by a predetermined distance.
One of it from the head, and adjacent heads are characterized by having a head group of two pairs having different azimuth angles 請
The auto-tracking device according to claim 1 or claim 2 . 4. A phase control reference signal generated by a reference signal generating means, being a signal generated based on a head switching signal of a cylinder or a signal generated based on a signal synchronized with the head switching signal. Claims characterized
2. The automatic tracking device according to 1 . 5. A particular at least two points of sampling by the sampling means, according to claim 1 or claim, characterized in that the width near both ends of the reproduction output of the period of time that is reproduced by a narrow head of a plurality of heads Item 6. The automatic tracking device according to Item 2 . 6. A sampling point by a sampling means.
Int is a sample that takes into account the delay in the low-pass filter.
3. A ring point,
The auto-tracking device according to claim 2.