JPH0383250A - Automatic tracking device - Google Patents

Abstract

PURPOSE:To attain accurate scanning without being influenced by an interference component by extracting a carrier chrominance signal crosstalk component from a color burst part and controlling it to a tracking phase where the crosstalk component becomes minimum. CONSTITUTION:A frequency modulation luminance signal YFM outputted from a filter circuit 13 is supplied to a peaking circuit 14 and a demodulation circuit 22. The circuit 22 demodulates the signal YFM and supplies a luminance signal Y to a synchronizing signal separation circuit 23. The circuit 23 separates a synchronizing signal from the signal Y and supplies it to a gate signal generation circuit 24. The circuit 24 generates a gate pulse in a position where a color burst exists with the synchronizing signal as a reference. A gate circuit 25 causes the crosstalk component to pass only while the gate pulse is outputted and supplies it to a peak detection circuit 26. The circuit 26 supplies a crosstalk level obtained by holding the peak level of the crosstalk component to a micro computer 16. The computer 16 obtains a delay time when the crosstalk level comes to the minimum and sets it to a capstan servo system 11.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an automatic tracking device that allows a rotary head to accurately scan recording tracks on a magnetic tape during reproduction by a magnetic recording and reproducing device. .

[Conventional technology]

FIG. 2 is a block diagram showing a conventional automatic tracking device. In the figure, 1 is a frequency sporadic generator 1tIla that is attached to the motor shaft of a capstan motor and monitors the rotational speed of the capstan motor, and 2 is a frequency generator. a speed error detection circuit that detects a speed error of the capstan motor based on the capstan FC signal output from the machine 1;
3 is a control signal generation circuit that mixes the speed error signal output from the speed error detection circuit 2 and the phase error signal output from the phase error detection circuit 10 (described later) and outputs an inverted control signal; 4 is a control signal generation circuit; A capstan motor drive device that drives the capstan motor 5 based on the control signal outputted from the signal generation circuit 3; 5 is a capstan motor drive device;
This is a cab stan motor that is driven by the motor drive device 4 and runs the magnetic tape. 6 is a reference signal generation circuit that supplies a reference signal to a drum servo system and a capstan servo system, which will be described later, and 7 is a rotary rad 12, which will be described later.
8 is a drum servo system that controls a drum equipped with a drum servo system, and 8 delays a drum servo system reference signal output from a reference signal generation circuit 6 by a time set by a delay time setting signal from a microcomputer 16, which will be described later. 9 is a control head that reads control pulses from a control track on the magnetic tape; 10 is a control head that detects the phase error of the control pulse outputted from the control head 9 and outputted from the variable delay circuit 8; This is a phase error detection circuit that detects based on the capstan servo system reference signal. The above frequency generator 1. Speed error detection circuit 2. Control signal generation circuit 3.
Capstan motor drive 4. Capstan motor5. Variable delay circuit 8. Control head9. and the capstan servo system 11 from the phase error detection circuit 10
is configured. 12 is a rotating head that reads a frequency multiplexed signal of a frequency modulated luminance signal and a low frequency converted color signal from a recording track on the magnetic tape; 13 is a rotary head that removes the low frequency converted color signal from the frequency multiplexed signal output from the rotating head 12; ,
14 is a peaking circuit that applies peaking to the frequency modulated luminance signal output from the filter circuit 13; 15 is a peak detection circuit that maintains the peak level of the output signal of the peaking circuit 14; 16; observes the envelope level of the frequency modulated luminance signal output from the peak detection circuit 15,
This is a microcomputer that outputs the delay time setting signal for setting the delay time of the variable delay circuit 8.

The zero-frequency generator 1, whose operation will be described next, outputs a capstan FC signal having a frequency corresponding to the rotational speed of the capstan motor 5. The speed error detection circuit 2 detects the speed error of the capstan motor 5 from this capstan FG signal and outputs a speed error signal. The control signal generation circuit 3 mixes the speed error signal and a phase error signal described later in a predetermined ratio, and outputs an inverted control signal. The capstan motor drive device 4 drives the capstan motor 5 based on the control signal so as to cancel out the speed error and phase error.

Next, the process of generating the phase error signal will be described. The reference signal generation circuit 6 generates a drum servo system reference signal that serves as a reference for the drum servo system 7.

The variable delay circuit 8 delays the drum servo system reference signal by a time corresponding to a delay time setting signal, which will be described later, and outputs a capstan servo system reference signal. The variable delay circuit 8 changes the phase relationship between the magnetic tape controlled by the capstan servo system 11 and the rotating disk 12 controlled by the drum servo system. At this time, the delay time of the variable delay circuit 8 is set by the delay time setting signal so as to establish a phase relationship that allows the rotary head 12 to accurately scan the recording track on the magnetic tape.

The control head 9 reads the control pulse from the control track on the magnetic tape. The phase error detection circuit 10 detects the phase error of the control pulse based on the capstan servo system reference signal, and detects the phase error. Outputs error signal.

Next, the process of generating the delay time setting signal will be described.
The rotary head 12 scans the recording track on the magnetic tape and outputs a frequency modulated luminance signal: Y, , and a low frequency conversion color signal: C.
L frequency multiplexed signal: Read S, filter circuit 13
supply to. The filter circuit 13 has characteristics of a high-pass filter that blocks the low frequency range where the low-pass converted color signal CL exists and passes the high frequency range where the frequency modulated luminance signal Y□ exists. The filter circuit 13 converts the frequency multiplexed signal: S to the frequency modulated luminance signal: Y7,
is extracted and supplied to the peaking circuit 14. The peaking circuit 14 applies peaking to the frequency modulated luminance signal (YFM) at a specific frequency! The signal is output to the peak detection circuit 15 after removing the influence of the frequency characteristics of the magnetic conversion system. The peaking frequency of the peaking circuit 14 is set to the lower frequency of the frequency deviation when frequency modulating the luminance signal, that is, the frequency corresponding to the synchronization tip portion. The peak detection circuit 15 holds the peak level of the peaked frequency modulated luminance signal Yn and obtains an envelope level obtained by converting the amplitude level of the reproduced signal into a DC component. The microcomputer 16 operates to monitor the envelope level and set a delay time in the variable delay circuit 8 so that the rotary head 12 can accurately scan the recording track on the magnetic tape. When the rotary head 12 is accurately scanning the recording track on the magnetic tape, the envelope level takes the maximum value. The envelope level decreases whether the delay time is large or small. That is, whether or not the rotary head 12 is accurately scanning the recording track on the magnetic tape can be determined by observing the envelope level of the reproduced signal. Therefore, micro
The computer 16 decreases the delay time set in the variable delay circuit 8 for a certain period of time and increases it for a certain period of time, observes changes in the input envelope level, and determines the peak value of the change at which the envelope level becomes maximum. is detected, and a delay time setting signal for setting the delay time of the variable delay circuit 8 is output.

[Problem to be solved by the invention]

Conventional automatic tracking devices are configured to monitor and control the envelope level of the reproduced signal as described above, so they can detect interference components such as crosstalk caused by the rotating head over-reading adjacent tracks and the correct track. When the influence of interference components is large in a reproduced signal mixed with signal components from There were problems such as doing the following.

This invention was made to solve the above-mentioned problems, and is an automatic tracking system that allows a rotating head to accurately scan recording tracks on a magnetic tape without being affected by interference components such as crosstalk. The purpose is to obtain equipment.

[Means to solve the problem]

The automatic tracking device according to the present invention frequency-converts a reproduced low frequency conversion color signal into a carrier color signal, detects a crosstalk component from an adjacent track from the carrier color signal with a filter having a comb characteristic, and detects the crosstalk component from the carrier color signal using a filter having a comb characteristic. The crosstalk component of the color burst portion is extracted from the color burst components, and the tracking phase of the rotary head and magnetic tape, which is controlled by the amplitude level of the reproduction frequency modulation signal, is finely adjusted using this crosstalk component.

[Operation] The automatic tracking device according to the present invention detects the crosstalk component in the vicinity of the tracking phase of the rotary head and the magnetic tape where the amplitude level of the reproduced frequency modulation signal reaches its maximum value, thereby minimizing the crosstalk component. Since the tracking phase is controlled to the following, accurate scanning can be performed without being affected by interference components.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of an automatic tracking device according to an embodiment of the present invention, and in the figure, the same reference numerals as in FIG. 2 represent the same or corresponding parts.

Further, reference numeral 17 denotes a second unit that removes the frequency modulated luminance signal from the frequency multiplexed signal of the frequency modulated luminance signal and the low frequency converted color signal outputted from the rotary head 12, and extracts the low frequency converted color signal.
A filter circuit 18 converts the frequency of the low frequency conversion color signal outputted from the second filter circuit 17 to obtain a carrier color signal, and 19 converts the carrier color signal outputted from the frequency conversion circuit 18 into 1. Delay by horizontal scanning period l
H delay circuit 20 is the output signal of the frequency conversion circuit 18 and I
This is an adder circuit that adds the output signal of the H delay circuit 19, and the IH delay circuit 19 and the adder circuit 20 constitute a crosstalk component extraction filter circuit 21. 22 is a demodulation circuit that demodulates the frequency modulated luminance signal output from the first filter circuit 13 to obtain a luminance signal; 23 is a synchronization signal separation circuit that separates only the synchronization signal from the luminance signal output from the demodulation circuit 22; Reference numeral 24 refers to a gate signal generation circuit that generates a gate pulse at a position where a color burst exists based on the synchronization signal output from the synchronization signal separation circuit 23; A gate circuit 26 is a gate circuit 25 which gates with the gate pulse output from the signal generation circuit 24 and outputs the crosstalk component of the color burst portion.
This is a second peak detection circuit that holds the peak level of the signal output from the second peak detection circuit.

Next, the operation will be explained. The rotary head 12 scans the recording track on the magnetic tape and outputs a frequency modulated luminance signal: y
A frequency multiplexed signal: S of rx and low-pass converted color signal 20L is read and supplied to the first filter circuit 13 and at the same time, supplied to the second filter circuit 17. Second filter time B
Reference numeral 17 has characteristics of a low-pass filter that blocks the high frequency range where the frequency modulated luminance signal Y8 exists and passes the low frequency range where the low frequency conversion color signal CL exists.

The second filter circuit 17 extracts the low frequency converted color signal 20L from the frequency multiplexed signal:S, and the frequency conversion circuit 1
Supply to 8. The frequency conversion circuit 18 converts the frequency of the low frequency conversion color signal: CL to obtain a carrier color signal: C. IH
The delay circuit 19 delays the carrier color signal C output from the frequency conversion circuit 18 by one horizontal scanning period.

The adder circuit 20 adds the output signal of the frequency conversion circuit 1st and the output signal of the IH delay circuit 19, and outputs a crosstalk component. The IH delay circuit 19 and the addition circuit 20 include a crosstalk component extraction filter circuit 21 having a comb characteristic for extracting a losstalk component from a forward color signal from an adjacent track that has a frequency interleave relationship with the carrier color signal 20. It consists of The frequency modulated luminance signal (YFM) output from the first filter circuit 13 is supplied to the demodulation circuit 22 at the same time as the peaking circuit 14 . The demodulation circuit 22 demodulates the frequency modulated luminance signal YF-i outputted from the first filter circuit 13 and supplies the luminance signal Y to the synchronization signal separation circuit 23 .

The synchronization signal separation circuit 23 separates a synchronization signal from the luminance signal Y output from the demodulation circuit 22 and supplies it to the gate signal generation circuit 24 . The gate signal generation circuit 24 generates a gate pulse at a position where a color burst exists based on the synchronization signal outputted from the synchronization signal separation circuit 23, and supplies it to the gate circuit 25. Gate circuit 25
allows the crosstalk component outputted from the adder circuit 20 to pass through only while the gate pulse indicating the period in which the color burst outputted from the gate signal generation circuit 24 exists; is not output, it operates so as not to pass the above-mentioned crosstalk component. Therefore, the gate circuit 25 supplies the crosstalk component of the color burst portion to the second peak detection circuit 26. The second peak detection circuit 26 holds the peak level of the crosstalk component output from the gate circuit 25 and supplies the obtained crosstalk level to the microcomputer 16. micro computer 1
6, the rotary head 12 detects the recording track on the magnetic tape by observing changes in the envelope level output from the first peak detection circuit 15 and the crosstalk level output from the second peak detection circuit 26. The variable delay circuit 8 operates to set a delay time that allows accurate scanning of the variable delay circuit 8. The microcomputer 16 decreases the delay time set in the variable delay circuit 8 for a certain period of time and increases it for a certain period of time, and observes changes in the input envelope level and the crosstalk level,
Delay time setting that detects the peak value of the change at which the envelope level is maximum, further determines the delay time at which the crosstalk level is minimum in the vicinity of the peak value, and sets the delay time of the variable delay circuit 8. Output a signal.

In the above embodiment, the crosstalk level is input to the microcomputer 16, and at the same time, the envelope level of the frequency modulated luminance signal is input to the rotary head 1.
2 and the tracking phase of the magnetic tape are controlled, however, the envelope level of the frequency modulated audio signal may be input to the microcomputer 16 at the same time as the crosstalk level. The crosstalk level may be controlled by simultaneously inputting a mixture of the envelope level of the frequency modulated luminance signal and the frequency modulated audio signal at a predetermined ratio.

Further, in the above embodiment, the crosstalk component extraction filter circuit 25 composed of the IH delay circuit 23 and the addition circuit 24 is used to extract the crossstroke component. Any filter may be used as long as it can extract carrier color signal crosstalk components from adjacent tracks that are in a frequency interleaved relationship with the signal.

For example, FIG. 3 is a block diagram illustrating another configuration of a filter capable of extracting crosstalk.

The operation will be explained with reference to the diagram. 27 receives the carrier color signal and is connected to the first 1H delay circuit 28;
This is an input terminal also connected to the 1/4 attenuation circuit 30 of.

The first H delay circuit 28 generates a second carrier color signal: Ct, which is obtained by delaying the first carrier color signal: C1 by l horizontal scanning period.
is supplied to the second IH delay circuit 29, and at the same time, 1/2
It is supplied to the attenuation circuit 31. The second IH delay circuit 29 generates a third carrier color signal C1 obtained by delaying the second carrier color signal C1 by one horizontal scanning period and outputs the second carrier color signal C1 to the second 1/4 attenuation circuit 3.
Supply to 2. The first 1/4 attenuation circuit 30 converts the first carrier color signal CI applied to the input terminal 27 into 1/4.
The signal is attenuated and supplied to the adder circuit 33. 1/2 attenuation circuit 3
1 attenuates the second carrier color signal: 02 outputted from the first 1H delay circuit 28 to 172 and supplies it to the addition circuit 33. The second 1/4 attenuation circuit 32 receives the third carrier color signal 20 output from the second IH delay circuit 29.

is attenuated to 1/4 and supplied to the adder circuit 33. The adder circuit 33 receives the output signal of the first 1/4 attenuation circuit 30, the output signal of the 1/2 attenuation circuit 31, and the second 1/4 attenuation circuit 32.
The three systems of output signals are added to obtain a crosstalk signal, which is output from the output terminal 45.

Further, FIG. 4 is a block diagram illustrating still another configuration of a filter capable of extracting crosstalk abrasion, and the operation will be explained with reference to FIG. Reference numeral 27 denotes an input terminal to which a carrier color signal is input, which is connected to the first IH delay circuit 28 and also connected to the first inversion circuit 34 . The first IH delay circuit 28 outputs a second conveyed color signal 2C8, which is obtained by delaying the first conveyed color signal 20 by l horizontal scanning period, to a second IH delay circuit 28.
At the same time, the first. The second minimum value circuit 36,37 and the first. Second maximum value circuit 39, 40
, and the subtraction circuit 44. Second IH delay circuit 2
Reference numeral 9 denotes a third carrying color signal 2C1 which is obtained by delaying the second carrying color signal 202 by one horizontal scanning period, and transmits the third carrying color signal 2C1 to a second inverting circuit 3.
Supply to 5.

The first inversion circuit 34 inverts the first carrier color signal 2C1 applied to the input terminal 27, and the first minimum value circuit 34 inverts the first carrier color signal 2C1 applied to the input terminal 27.
6 and the first maximum value circuit 39. The second inversion circuit 35 receives the third carrier color signal 20 outputted from the second LH delay circuit 29.

is inverted and supplied to the second minimum value circuit 37 and second maximum value circuit 40. The first minimum value circuit 36 receives the first carrier color signal C3 outputted from the first inversion circuit 34 and the second carrier color signal C2 outputted from the first IH delay circuit 28. The smaller of the two signals is output and supplied to the third maximum value circuit 38. The second minimum value circuit 37 receives the second carrier color signal: 02 outputted from the first 1H delay circuit 28 and the third carrier color signal 2C1 outputted from the second inversion circuit 35. The smaller of the two signals is output and supplied to the third maximum value circuit 38. The third maximum value circuit 38 receives the output signals of ml and the second minimum value circuits 36 and 37, outputs the larger signal of both, and supplies it to the adder circuit 42. The first maximum value circuit 39 receives the first carrier color signal: CI outputted from the first inversion circuit 34 and the second carrier color signal: 02 outputted from the first 1H delay circuit 28. The larger of the two signals is output and supplied to the third minimum value circuit 41. The second maximum value circuit 40 is the first IH delay circuit 28
and the third carrier color signal 2C output from the second inversion circuit 35.
1 is input, and the larger signal of both is outputted and supplied to the third minimum value circuit 41. The third minimum value circuit 41 receives the output signals of the first and second maximum value circuits 39 and 40, outputs the smaller signal of both, and supplies it to the adder circuit 42. The adder circuit 42 adds the output signal of the third maximum value circuit 38 and the output signal of the third minimum value circuit 41 and supplies the sum to the attenuation circuit 43 . The attenuation circuit 43 attenuates the output signal of the addition circuit 42 to 1/2 to obtain a carrier color signal C from which the crosstalk component is removed, and supplies it to the subtraction circuit 44 . The subtraction circuit 44 receives the second signal output from the first IH delay circuit 28.
The crosstalk component-free carrier color signal C output from the attenuation circuit 43 is subtracted from the carrier color signal 202 to obtain the crosstalk component, which is output from the output terminal 45.

Note that the crosstalk component extraction filter circuit 25 in the above embodiment and the filter circuit shown as an example of a filter capable of extracting a carrier color signal crosstalk component from an adjacent track that is in a frequency interleaved relationship with other carrier color signals are as follows. NT as a signal handled by magnetic recording and reproducing equipment
Although the configuration is shown assuming an SC system TV signal, the IH delay circuit 23 that delays the input signal by one horizontal scanning period or the first . By replacing the second IH delay circuits 28 and 29 with 2H delay circuits that delay the input signal by two horizontal scanning periods, the present invention can also be applied to PAL TV signals.

Further, in the above embodiment, the gate circuit 25 is replaced with the crosstalk component extraction filter circuit 21 and the second peak detection circuit 26.
Although the gate circuit 25 is shown to be provided between the frequency conversion circuit 18 and the crosstalk component extraction filter 21,
It may be provided in between.

[Effects of the Invention] As described above, according to the present invention, since the crosstalk component of the carrier color signal is extracted from the color burst portion, the correct crosstalk component can be extracted even in an image pattern without vertical correlation. Furthermore, the tracking phase of the rotating head and magnetic tape, which is controlled by the amplitude level of the reproduction frequency modulation signal using the above-mentioned crosstalk component, is determined by WLU.
Since the rotary head is configured to have four alignments, there is an effect that the rotary head can accurately scan the recording track on the magnetic tape without being affected by interfering components such as crosstalk.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an automatic tracking device according to an embodiment of the present invention, FIG. 2 is a block diagram showing a conventional automatic tracking device, and FIG. 3 is a block diagram showing another configuration example of a filter capable of extracting crosstalk components. Block diagram shown, No. 4
The figure is a block diagram showing yet another configuration example of a filter capable of extracting crosstalk components. 1 is a frequency generator, 2 is a speed error detection circuit, 3 is a control signal generation circuit, 4 is a capstan motor drive device, 5 is a capstan motor, 6 is a reference signal generation circuit, 7 is a drum servo system, 8 is a variable delay circuit, 9 is a control head, 10 is a phase error detection circuit, 11 is a capstan servo system, 12 is a rotating head, 13 is a first filter circuit, 14 is a peaking circuit, 15 is a peak detection circuit , 16 is a microcomputer, 17 is a second filter circuit, 18 is a frequency conversion circuit, 19 is a 1H delay circuit,
20, 33, 42 is an adder circuit, 21 is a crosstalk component extraction filter 5 circuit, 22 is a demodulation circuit, 23 is a synchronization signal separation circuit, 24 is a gate signal generation circuit, 25 is a gate circuit, and 26 is a second peak detection circuit. circuit, 27 is an input terminal, 28
．． 29 is the first and second IH delay circuit, 30 is the first 1/1
4 attenuation circuits, 31 is a 1/2 attenuation circuit, 32 is a second 1/2 attenuation circuit, and 32 is a second 1/2 attenuation circuit.
4 attenuation circuit, 34.35 is the first. second inversion circuit, 36
．． 37 is the first. 2nd minimum value circuit, 38 is the third maximum value circuit, 39.40 is the first . a second maximum value circuit, 41 a third minimum value circuit, 43 an attenuation circuit, 44 a subtraction circuit, 4
5 is the output terminal. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] (1) In an automatic tracking device that detects the amplitude level of a reproduction frequency modulation signal reproduced by a rotary head of a magnetic recording and reproducing device, and controls the tracking phase of the rotary head and the magnetic tape based on the amplitude level, a reproduction low frequency means for frequency converting a converted color signal into a carrier color signal; means for detecting a carrier color signal crosstalk component from an adjacent track having a frequency interleaved relationship with the carrier color signal from a color burst portion; 1. An automatic tracking device comprising: the rotary head; and means for finely adjusting the tracking phase of the magnetic tape.