KR0176145B1 - Automatic tracking control method - Google Patents

Abstract

The automatic tracking control method is for reproducing the driving efficiency of the piezoelectric element for controlling the magnetic head to be displaced in the width direction with respect to the recording track in the video and audio signal recording and reproducing apparatus including the piezoelectric element with the head mounted thereon. . According to the present invention, two heads having different azimuth angles, a plurality of electromechanical conversion elements equipped with heads, key input means for inputting a user's control command and information, and the plurality of heads according to signals of the key input means are provided. A system controller for controlling the driving of the electromechanical conversion element, and setting a predetermined preset value for controlling the driving of the electromechanical conversion element by the control signal of the key input means; Detecting a head in contact with the medium, and applying a preset value applied to the electromechanical conversion element of the head in contact with the recording medium according to the detection process. Therefore, deformation of the piezoelectric element can be reduced and strength degradation can be prevented.

Description

Auto tracking control method

1 is an embodiment of an automatic tracking control device for carrying out the present invention.

FIG. 2 is a flowchart of preset value setting for automatic tracking control of the present invention made in the system controller of FIG.

FIG. 3 is a flow chart for a timer interrupt in parallel with FIG. 2 and operation within the system controller of FIG.

4 shows a head scan trajectory and a recording track during 4x reproduction, which is an embodiment of the present invention.

5 is a voltage waveform diagram applied to the head switching signal and the electromechanical converter according to FIG.

6 and 7 illustrate a 9x speed according to another embodiment of the present invention.

8 and 9 are about double speed, which is another embodiment of the present invention.

10 and 11 are for a triple speed, which is another embodiment of the present invention.

* Explanation of symbols for main parts of the drawings

10: key input means 20: system controller

30, 31: D / A converter 40, 41: drive circuit

50, 51: electromechanical conversion element or head piezoelectric element

60, 61: preamplifier 70: tracking error detection circuit

80: playback signal processing unit 90: capstan servo unit

100: A / D Converter

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic tracking control method in a video and audio signal recording and reproducing apparatus, and more particularly, to an automatic tracking control method for noiseless reproduction in a special reproduction.

In general, video and audio signal recording and reproducing apparatuses include video cassette recorders (or video tape recorders, hereinafter referred to as VCRs), audio cassette recorders, optical disc players, and the like. For a playback device. In recent years, such a video and audio signal recording and reproducing apparatus has been put into practical use for an automatic tracking apparatus that enables a reproducing magnetic head to accurately scan a track on which a video signal is recorded. Most of these devices have a structure in which a magnetic head is mounted on an electromechanical conversion element composed of piezoelectric elements or the like to displace the magnetic head in the width direction of a recording track. The piezoelectric element is displaceable in the direction perpendicular to the drum rotation direction and controls the driving of the magnetic head in accordance with the applied voltage. The automatic tracking device using the piezoelectric element operates the magnetic head according to the track curvature during normal reproducing to obtain the best reproducing output or the scanning track of the recording track and the head when transferring the tape at a tape speed different from the recording time. Most of them are used to compensate for the relative phase shift of. The former is advantageous to compensate for mutual reproduction between VCRs having narrow tracks, and the latter is advantageous for obtaining a noiseless special reproduction image. In the latter case, for example, a head scan trajectory is conventionally reproduced by jumping at a double speed by a track recorded with A and B heads having different Azimuth angles. In the case of FIG. 4, an example of 4 times speed, the scanning trajectory of the head is made as shown by arrows 5 and 6, and the Ai track and the Bi track (i = 1, 2, 3, ...) are recorded as heads having different azimuth angles. Therefore, in the case of arrow 5, the reproduction output is obtained only when scanning on the A1 track and the A2 track, and the reproduction output is not obtained when scanning on the B1 and B2 tracks, and noise is generated. Therefore, as described above, in order to obtain a noiseless special reproduced image, an automatic tracking device for controlling the magnetic head to be displaced in the width direction of the recording track using an electromechanical conversion element has been put to practical use.

An object of the present invention is to provide an automatic tracking control method for noiseless reproduction by increasing the driving efficiency of a piezoelectric element, which is an electromechanical conversion element, in the widthwise displacement of a magnetic head as described above during special reproduction. In providing.

In order to achieve the above object, the present invention provides at least two or more heads having different azimuth angles, a plurality of electromechanical conversion elements provided with the number of heads, and mounted on the heads, and control commands and information of a user. In the video and audio signal recording and reproducing apparatus having a key input means for input and a system controller for controlling the driving of the plurality of electromechanical conversion elements in accordance with the signal of the key input means, the automatic tracking control method includes:

Variably setting a predetermined preset value for controlling the driving of the electromechanical conversion element according to the control signal of the key input means;

Detecting a head in contact with a recording medium among the plurality of heads;

And applying the preset value corresponding to the electromechanical conversion element of the head in contact with the recording medium according to the detection process.

Next, the present invention will be described in detail with reference to the illustrated drawings.

1 is an embodiment of a conventional automatic tracking control device for carrying out the present invention, which is a PG (Pulse Generator) of a key input means 10, a key input means 10, and a drum (not illustrated). A system controller 20 connected to a head switching pulse (HSW) generated based on the signal, two D / A converters 30 and 31 connected to the system controller 20, and a D / A converter, respectively. Driving circuits 40 and 41 connected to each of the fields 30 and 31, and connected to the driving circuits 40 and 41, respectively, and equipped with regeneration heads A-CH and B-CH, respectively. Output signals of the head piezoelectric elements 50 and 51, the preamplifiers 60 and 61 and the preamplifiers 60 and 61 connected to the respective heads A-CH and B-CH. A reproduction signal processing unit for processing a reproduction signal picked up from the heads A-CH and B-CH by one head switching signal HSW (hereinafter abbreviated as HSW) to be displayed on the display means (not illustrated); 80) and the output signals of the preamplifiers 60, 61. A tracking error detection circuit 70 using the call and HSW signals as input signals, an A / D converter 100 connected between the tracking error detection circuit 70 and the system controller 20, and a key input means 10; And a capstan servo unit 90 connected to the tracking error detection circuit 70.

FIG. 2 is a flowchart for setting a preset value for automatic tracking control of the present invention in the system controller 20 of FIG. 1. Steps 101 to 107 are a preset value setting process according to a predetermined rule. In the step, the interrupt routine shown in FIG. 3 is performed while the recording medium is in contact with the recording medium to perform the pickup operation of the head. Steps 109 and 110 are processes of initializing a timer value at the time when the operation starts.

3 is a flowchart of a timer interrupt in which operation is performed at a predetermined point in FIG. 2 in the system controller 20 of FIG. 1, that is, a flowchart performed in the NO process of steps 108 and 111 of FIG. Steps 114 and 115 are processes in which a timer value is increased by 1 each time a timer interrupt is applied, and steps 116 and 117 are processes of storing a head potential of switching points of each head A-CH and B-CH. Steps 118 to 123 are control signal processing processes applied to the head piezoelectric element 50 when A-CH is in contact with the recording medium, and steps 124 to 129 are head piezoelectric when B-CH is in contact with the recording medium. The control signal processing applied to the element 51 is performed.

4 shows a head scan trajectory and a recording track during 4x reproduction, which is an embodiment of the present invention.

5 is a voltage waveform diagram applied to the head switching signal HSW and the electromechanical conversion elements 50 and 51 according to FIG. 4, wherein (a) is a head switching signal and (b) displaces A head. Is a voltage waveform for displacing the B head, and (d) is a voltage waveform for displacing the conventional A head.

6 shows a head scan trajectory and a recording track during 9x reproduction, which is another embodiment of the present invention.

FIG. 7 is a voltage waveform diagram applied to the head switching signal HSW and the electromechanical conversion elements 50 and 51 according to FIG. 6, wherein (a) is a head switching signal and (b) displaces A head. And (c) is the voltage waveform for displacing the B head.

8 shows a head scan trajectory and a recording track during double speed reproduction, which is another embodiment of the present invention.

FIG. 9 is a diagram of voltage waveforms applied to the head switching signal HSW and the electromechanical conversion elements 50 and 51 according to FIG. 8, wherein (a) is a head switching signal and (b) displaces A head. And (c) is the voltage waveform for displacing the B head.

FIG. 10 shows a head scan trajectory and a recording track during triple speed reproduction as another embodiment of the present invention.

FIG. 11 is a voltage waveform diagram applied to the head switching signal HSW and the electromechanical conversion elements 50 and 51 according to FIG. 10, wherein (a) is a head switching signal and (b) displaces A head. And (c) is the voltage waveform for displacing the B head.

The operation of the present invention will then be described with reference to FIGS. 1 and 2, 3.

In particular, in the case of Figure 1 is a block diagram of a general automatic tracking control device having a head piezoelectric element 50, 51, the description of each block is almost as well known, but will be briefly described to help the understanding of the present invention. do.

The key input means 10 is for inputting a user's control command and signal, and can be used as a front panel or a remote control device of the VCR. The control command and signal described above in the present invention will be a speed command for special reproduction. For example, when a function key for 4x, 9x, 2x, 3x, etc. is controlled, the output signal for the 4x9x, 2x, 3x speed, etc. is sent to the system controller 20 and the capstan servo unit 90. The capstan servo unit 90 controls the tape running according to the applied speed command, and the system controller 20 outputs a signal for controlling the displacement command values of the head piezoelectric elements 50 and 51 according to the applied speed command. . At this time, the control signal applied from the system controller 20 to the head piezoelectric elements 50 and 51 passes through the D / A converters 30 and 31 and the driving circuits 40 and 41. The driving circuits 40 and 41 amplify the signals output from the D / A converters 30 and 31 to the extent that they can be applied to the head piezoelectric elements 50 and 51. The playback heads A-CH and B-CH mounted on the head piezoelectric elements 50 and 51 are controlled by the head piezoelectric elements 50 and 51 to control the tracking scan trajectories so as to pre-amplify the signals picked up from the recording medium. (60) and (61), the preamplifiers (60) and (61) are simultaneously applied to the tracking error detection circuit (70) and the reproduction signal processing unit (80). The reproduction signal processing unit 80 synchronizes the applied signal with the HSW signal to output a desired reproduction signal to the display means (not illustrated), and the tracking error detection signal is synchronized with the HSW to compare the relative relationship between the head and the tape. The tracking error is detected and applied to the A / D converter 100 and the capstan servo unit 90. The tracking error detection signal applied to the capstan servo unit 90 controls the tape driving behavior, and the tracking error detection signal applied to the A / D converter 100 is applied to the system controller 20 to apply the head actuator. Used to control

2 shows a process of setting in the system controller 20 a preset value applied to the head piezoelectric elements 50 and 51 according to the speed command applied from the key input means 10. As shown in FIG. First, when the speed command command is applied through the key input means 10, the head potential of the voltage applied to the A-CH is determined by the following equation and stored in the RAM indicated by VA (step 101). In other words, when the voltage to be applied to the head piezoelectric element 50 at the A-CH switching start point is N, the double speed, Is 0 or If the quotient of is even

If the quotient is odd

to be.

In step 102, the head potential of the voltage applied to the B-CH for the same control command as the speed command applied through the above-described key input means 10 is determined by the following equation and stored in the RAM indicated by VB. do. That is, the voltage to be applied to the B piezoelectric element at the start point of B-CH switching,

to be.

The head potential of the B head during the A-CH operation in step 103 is also determined by the following equation and stored in the RAM indicated by VC.

In step 104, the amount of inclination equivalent to one pitch divided by a predetermined number is calculated and stored in a RAM called DELTA. Where the pitch S of one pitch

S = (N-1) Tp / Tf (where Tf is one switching interval)

Steps 106 and 107 store the time of switching the voltage applied to the head piezoelectric elements 50 and 51 in the RAM, where TS1 is the A head voltage switching time and TS2 is the B head voltage switching time. These TS1 and TS2 values are about the voltage switching time of the A-CH piezoelectric element 50 at the respective double speeds so that the voltage applied to the piezoelectric element is 0 while the head is not in contact with the tape. same.

In operation 107, the head switching timing is stored in the TSW. As described above, steps 101 to 107 determine a preset value for driving control of the piezoelectric elements 50 and 51 according to the speed command applied through the key input means 10.

Step 108 is to determine whether the head currently connected to the tape is A-CH or B-CH. In the case of B-CH, the loop continues, and in the case of A-CH, the switch is switched to A-CH. It goes out of running the timer. In steps 109 and 110, the timer is operated and the counter value CNT is cleared so that the A-CH starts from zero when the A-CH contacts the tape. In step 111, the A-CH keeps looping corresponding to the A-CH while the A-CH is in contact with the tape, and is lost at the moment of switching to the B-CH.

3 is a timer interrupt routine that interrupts the loop while continuing the loop in steps 108 to 113 of FIG. 2 to change the drive voltage of the head piezoelectric elements 50 and 51 as desired with time.

In step 114, the timer is incremented by 1 each time an interrupt is applied. In steps 115 through 117, the A-CH switching timing is determined to determine the head potential of the A-CH and the head potential of the B-CH as A and B. Store in In step 118 and 119, the voltage applied to the B-CH is switched while the A-CH is in contact with the tape. This is to make the average voltage of the piezoelectric elements 50 and 51 become zero as mentioned above. Then, if the A-CH contacts the tape in steps 120 to 123, each time the voltage applied to the A-CH is interrupted, the predetermined increment is increased and the tracking error signal is summed to the piezoelectric elements 50 and 51. Is authorized. In steps 124 to 125, the voltage applied to the A-CH is switched while the B-CH is in contact with the tape.

In steps 125 to 129, if the B-CH is in contact with the tape, the voltage applied to the B-CH is increased every time an interrupt is applied, and the tracking error signal is added to the piezoelectric elements 50 and 51 together. .

4 shows the relationship between the scan trajectory and the recording track of the head during 4x reproduction, where the A track and the B track are recorded with heads having different azimuth angles. Arrow 1 shows the scanning direction of the magnetic head, and arrow 2 shows the moving direction of the magnetic tape. In this example, since the tape speed at the time of reproduction is four times faster than at the time of recording, the scanning trajectory of the head is made as shown by arrows 5 and 6. In order to control the displacement of the head in the width direction of the track by using the piezoelectric elements 50 and 51, the head scanning trajectories as shown by arrows 7, 3 in the case of A-CH and arrows 4 and 8 in the case of B-CH are used. This is done. However, in the case of the head scan trajectory of arrows 7 or 8, the maximum displacement voltage difference of the piezoelectric element 50 becomes 6Tp as shown in (d) of FIG. 4, whereas the arrows 3 and 4 tracks are shown in FIGS. 5 (b) and (c). As can be seen, the maximum displacement voltage difference becomes 3Tp, so it is preset in the system controller 20 to scan arrows 3 and 4 tracks.

The head switching signal shown in Fig. 5A is a signal synchronized with the rotational phase of the magnetic head, and represents a period in which each head is in contact with the magnetic tape. In the period in which the head switching signal is high logic, the period in which the A head is in contact with the magnetic tape is shown in the period in which the A head is low logic. As shown in (b) and (c), the applied voltage polarity is positive in the same direction as the moving direction of the magnetic tape, and the voltage level is expressed in track pitches (Tp). For example, in the case of head A, a voltage of -2Tp is applied when the head starts to contact the tape, and a voltage of + 1Tp is applied when the head falls from the tape. The locus 5, 6 shown in the figure can be changed to 3, 4.

This voltage value is preset by the above-described formula. For example, the voltage to be applied to the A and B-CH piezoelectric elements 50 and 51 at the switching start point is

ego

The slope of the voltage waveform

Becomes

The switching time when the head is not in contact with the tape

Becomes

When the double speed becomes higher, the scanning trajectory of the track is controlled to be at the switching intermediate portion, so that the voltage difference applied to the piezoelectric elements 50 and 51 can be reduced to 1/2. Proving this is the case of the 9x speed shown in FIGS. 6 and 7.

That is, in the case of 9 times speed according to the above-described formula,

It becomes

In the case of the 2x and 3x speeds shown in FIGS. 8 and 9, 10, and 11, exceptions to the matters described so far are performed as shown in the drawings.

As described above, the present invention is an automatic tracking control method of a video and audio signal recording and reproducing apparatus having a piezoelectric element equipped with a head, wherein the displacement of the piezoelectric element moving momentarily with respect to each double speed by a special reproduction control is small. By scanning the track of the same azimuth angle and making the average DC voltage applied to the piezoelectric element equal to 0, the piezoelectric element is not only deformed but also deteriorated in strength, thereby improving the driving efficiency of the piezoelectric element. There is this.

Claims (1)

At least two heads (A-CH and B-CH) having different azimuth angles and the number of the heads (A-CH and B-CH) are provided and the heads (A-CH and B-CH) are provided. A plurality of electromechanical conversion elements (50) and (51) respectively equipped with a plurality of keys, a key input means (10) for inputting a control command and information of a user, and the plurality of electromechanical conversion elements according to a signal of the key input means (10). In the video and audio signal recording and reproducing apparatus having the system controller 20 for controlling the driving of the electromechanical conversion elements 50 and 51, the automatic tracking control method is based on the control signal of the key input means 10. Variably setting a predetermined preset value for controlling driving of the electromechanical conversion elements 50 and 51, detecting a head in contact with a recording medium among the plurality of heads, and The preset value is applied to the electromechanical conversion element of the head in contact with the recording medium according to the detection process. Automatic tracking control method comprising the step of applying.