KR100214871B1 - Auto tracking controlling apparatus - Google Patents

Abstract

The present invention relates to an automatic tracking control method for a magnetic recording and reproducing apparatus, and more particularly, to an automatic tracking control method for minimizing the time required for tracking during signal reproduction.

This automatic tracking control method includes a first step of switching to a still picture mode upon initial operation after loading a cassette, and a second step of controlling the tracking control by a video envelope detection value detected in accordance with forward and reverse rotation of the video head in the still picture mode. And a third step of switching to a reproduction mode when the tracking control direction is determined and performing tracking in the determined control direction.

Description

Automatic tracking control method

FIG. 1 is a configuration diagram of an automatic tracking control device for explaining tracking control at the time of signal reproduction in a general magnetic recording and reproducing apparatus; FIG.

FIG. 2 is a flow chart of an operation of an automatic tracking control method according to an embodiment of the present invention; FIG.

DESCRIPTION OF THE REFERENCE NUMERALS

1: Tape 3: Video Head

5: amplifier 7: envelope detector

9: Low-pass filter 11:

13: Capstan motor drive 15: Capstan motor

17: CTL head

The present invention relates to an automatic tracking control method for a magnetic recording and reproducing apparatus, and more particularly, to an automatic tracking control method for minimizing the time required for tracking during signal reproduction.

In the magnetic recording and reproducing apparatus, the tracking control is to accurately read the information recorded on the recording medium so that a clear picture can be obtained in which only the video signal containing the noise signal is outputted at the minimum. The tracking control means that the positional relationship between the head driven by the drum motor and the tape driven by the capstan motor in the magnetic recording and reproducing apparatus is maintained in a constant relationship so that the video head accurately tracks the track on the tape .

Hereinafter, the conventional automatic tracking control device will be described in detail.

FIG. 1 is a configuration diagram of an automatic tracking control device for explaining tracking control at the time of signal reproduction in a general magnetic recording and reproducing apparatus.

An amplifier 5 for amplifying a signal reproduced by the head 3 to a predetermined magnitude; and an amplifier 5 for amplifying the output signal of the amplifier 5, An envelope detector 7 for detecting an envelope of a high frequency signal in the envelope detector, a low pass filter 9 for smoothing the envelope detected by the envelope detector and removing a noise signal of a high frequency component, And a control unit 11 for controlling the capstan motor driving unit 13 until the maximum video envelope voltage value is obtained by comparing the current input value with the input value one frame before.

A capstan motor 15 for driving the tape 1 at a constant speed under the control of the capstan motor driving unit 13 and controlling the phase so that accurate tracking is performed, (Hereinafter referred to as " CTL head ") 17 for outputting a CTL signal (hereinafter referred to as " CTL signal "). The CTL signal refers to a signal recorded on a tape to indicate the position (phase) of a video track recorded on the tape. Therefore, at the time of reproduction, the CTL head 17 reproduces the CTL signal from the tape and quickly shifts the capstan motor 15 in the direction of increasing or decreasing the number of the reproduction signal compared to the reference signal The phase control is performed until the maximum video envelope voltage value is found in the control unit 11 while controlling the video envelope voltage,

The control operation of the automatic tracking control device having the above-described configuration will now be described.

First, the tracking control described in the present invention precedes the operation description means the tracking control operation performed immediately before the video signal is reproduced after the cassette is loaded.

Therefore, once the control unit 11 recognizes that the cassette is seated in the loading apparatus, the control unit 11 applies a control signal to the capstan motor driving unit 13 to rotate the capstan motor 15 in the forward direction (or reverse direction). At this time, the initial stage of reproduction is set to a tracking preset state.

Thus, the information recorded on the tape 1 is read out from the video head 3 while the initial reproducing operation is started. The signal reproduced by the video head 3 is firstly amplified by the amplifier 5 and output to the envelope detector 7. An envelope is detected in a signal input to the envelope detector 7, and the envelope is input to a low-pass filter 9 to remove a smooth and high-frequency noise signal. The video envelope signal output from the low-pass filter is input to the controller 11, converted into a digital signal by the controller 11, and temporarily stored in a memory device (not shown).

On the other hand, in a state in which the information recorded on the tape 1 is read and the process of detecting a video envelope signal is proceeded, the CTL head 17 reproduces the CTL signal recorded on the tape 1. The regenerated CTL signal is input to the capstan motor driving unit 13, compares a reference signal generated using a signal generated from an X-Tal OSC (not shown) with a CTL signal, .

When the capstan motor 15 continuously rotates in a direction in which the CTL signal reproduced in the CTL head 17 is reduced by the calculated difference signal, Detecting the video envelope signal before the video envelope voltage is changed from the minimum value to the decreasing value by comparing the video envelope signal to be stored in advance with the value stored in advance (the amplitude of the video envelope signal through the magnetic head-amplifier- envelope detector- Quot; and " the envelope signal is detected "). Of course, the video envelope signal detected after performing the series of processes until the video envelope signal is detected is updated and stored in the memory device until a maximum value is obtained.

When the detected video envelope signal is compared with a previous value of the video envelope signal while the process of detecting the video envelope signal is being performed, And rotates the capstan motor 15 in the reverse direction (or forward direction).

The capstan motor 15 is rotated in the reverse direction and a series of operations are performed until the video envelope signal is detected by reading the information recorded on the tape 1 through the video head 3. At the same time, (17), the CTL signal is reproduced. This CTL signal is input to the capstan motor driving unit 13 and is compared with the CTL signal by using a reference signal generated using a signal oscillated by an X-Tal OSC (not shown) built therein, and the difference signal is calculated . Then, the maximum value of the magnetic envelope signal is detected while the capstan motor 15 is continuously rotated in the direction increasing by the difference signal.

In other words, when the capstan motor 15 rotates in a direction in which the CTL signal is increased by the difference signal, the controller 11 controls the driving of the capstan motor 15 until the detected video envelope signal is switched from the maximum value to the decreasing value. After a series of processes in which the CTL signal detected by the CTL head 17 up to the above is reduced or increased based on the preset state at the initial stage of reproduction is performed, the maximum video envelope signal . Then, the maximum video envelope signal is moved to the calculated position, and the phase control of the capstan motor 15 is performed based on this position.

As described above, in the conventional automatic tracking control, in order to obtain the maximum video envelope voltage detected from the high frequency signal reproduced without a specific reference value, the video envelope voltage is obtained in both the direction in which the CTL signal is increased and the direction in which the CTL signal is decreased After performing the operation, normal tracking control was started at the maximum video envelope voltage position. In other words, since the automatic tracking control operation is performed together with the execution of the reproducing operation, it takes a long time and the output while the tracking control is performed is displayed on the screen as it is.

Therefore, the conventional automatic tracking control has a problem that it takes a long time until the head is correctly positioned on the track after the cassette is loaded, and also because the phase of the capstan motor continuously changes in the tracking control state, There is a problem that the phenomenon in which the screen is shaken is outputted as it is.

Accordingly, it is an object of the present invention to provide an automatic tracking control method capable of minimizing a time required for tracking control in an initial reproduction operation.

It is another object of the present invention to provide an automatic tracking control method capable of performing tracking control in a still picture state and mute a screen output in an initial reproduction operation.

According to another aspect of the present invention, there is provided an automatic tracking control method comprising: a first step of switching to a still image mode upon initial operation after loading a cassette; A second step of determining a tracking control direction based on a video envelope detection value detected according to the detected video envelope detection value, and a third step of performing tracking in the determined control direction by switching to the playback mode when the tracking control direction is determined .

The automatic tracking control method according to the embodiment of the present invention performs the tracking control performed in the initial reproduction operation in the still picture mode. That is, the most important feature of the present invention is to perform the operation for determining whether the capstan motor 15 should be rotated or rotated in the direction of increasing the CTL signal before the reproducing operation for the automatic tracking performing operation . Therefore, after the determination operation is performed, the tracking control is performed by rotating the capstan motor in one direction of the direction in which the CTL signal increases or decreases.

Therefore, after the rotation direction is determined in the still picture mode, the tracking control is performed while the reproduction operation is performed, and the switching control operation from the still picture mode to the reproduction mode is performed under the control of the microcomputer, . Also, in the still image mode, the screen output is muted so as to minimize a screen output phenomenon such as screen shake on the user's eyes.

Hereinafter, an automatic tracking control method according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a flow chart showing an automatic tracking control method according to an embodiment of the present invention.

The hardware configuration in which the automatic tracking control method of the present invention is performed is the same as that of the automatic tracking control device of a general magnetic recording and reproducing apparatus, and will be described with reference to FIG.

First, the configuration shown in FIG. 1 will be examined again. An amplifier 5 for amplifying a signal reproduced by the head 3 to a predetermined magnitude; and an amplifier 5 for amplifying a high frequency signal from the output signal of the amplifier 5, A low pass filter (9) for smoothing an envelope detected by the envelope detector and removing a noise signal of a high frequency component, an envelope detector (7) for detecting an envelope, And a controller 11 for performing automatic tracking control according to an embodiment of the present invention. The control unit 11 is characterized by using a microcomputer.

The capstan motor driver 13 drives the tape 1 at a constant speed under the control of the capstan motor driver 13 and controls the phase of the tape 1 so that accurate tracking is performed. A motor 15 and a head 17 (hereinafter referred to as a CTL head) for outputting a control signal (hereinafter, referred to as 'CTL signal') used for phase control in a reproducing operation. The CTL signal refers to a signal recorded on a tape to indicate the position (phase) of a video track recorded on the tape. Therefore, at the time of reproduction, the CTL head 17 reproduces the CTL signal from the tape.

Next, an automatic tracking control method of the present invention will be described based on the hardware configuration.

If the microcomputer 11 recognizes that the cassette is once loaded on the loading device and is loaded, it is determined whether the cassette is currently in the automatic tracking control mode (operation 101). The automatic tracking control mode may be automatically entered after the cassette is seated in the loading apparatus or may be entered into the automatic tracking control mode state at the user's selection.

If the automatic tracking control mode is selected in operation 101, the microcomputer 11 switches the operation of the magnetic recording and reproducing apparatus to the still picture mode (operation 103).

The still picture mode refers to a state in which the tape running is stopped and the video head rotates normally. As a result, since the tape is stopped, it becomes a still picture. The control according to this still picture is as follows. The control signal is applied from the microcomputer 11 to the capstan motor driving unit 13 to stop the operation of the capstan motor 15 which generates the power for driving the tape 1. [ At this time, the capstan motor 15 detects the CTL signal recorded on the tape 1 at the CTL head 17 and then stops after a predetermined time T1 elapses. In this still image, the video head is in a state in which the recording track is obliquely interlaced in order to stop the tape.

The video head 3 is rotating even in the state where the tape 1 is stopped and therefore the information recorded on the tape 1 is read out and outputted to the amplifier 5. The amplifier 5 amplifies an input signal by a predetermined amount and outputs the amplified signal. The output signal is input to an envelope detector 7 and an envelope is detected. After the noise signal of the high frequency component is removed through the low-pass filter 9, the signal is input to the microcomputer 11.

At this time, the video envelope signal input to the microcomputer 11 is converted into a video signal, which is input to the microcomputer 11, depending on where the CTL signal reproduced in the CTL head 17 is compared with the position of the reference signal, The voltage difference appears in the direction of rotation of the video head 3 in the envelope signal.

The CTL signal detected through the CTL head 17 is input to the capstan motor driving unit 13, and the built-in X- And compares the position of the CTL signal with the reference signal generated using the signal oscillated from the Tal OSC (not shown). When the CTL signal is detected at the same position as the preset position (reference position) in the positional comparison with the reference signal, a magnetic envelope signal of a positive symmetry in the rotational direction of the video head 3 is detected.

Here, the video head 3 used for video envelope signal detection is assumed to have a narrow head width in a magnetic recording and reproducing apparatus using one or more video heads, and a positive symmetric video detected in the rotational direction of the video head 3 The envelope signal is based on a switching pulse for selecting a video head to reproduce a signal recorded on a recording track. That is, the detected video envelope signal is a signal output from the rising edge R to the falling edge P of the switching pulse for selectively outputting the signal of the video head 3 (operation 105).

Accordingly, when the CTL signal is detected at the preset position, the video envelope signal detected through the video head 3 is positively symmetric from the rising edge (R) portion of the video head selection output pulse to the falling edge (P) Is detected. When a positive symmetric envelope signal is detected in this manner, this means that the overlapping portion of the recording track and the video head 3 coincides with each other, indicating that no automatic tracking operation is required.

That is, in this state, the phase for tracking control of the capstan motor 15 in the reproducing operation is controlled based on this position. However, when the CTL signal reproduced through the CTL head 17 is located at the front side compared with the preset position, the rising edge of the video head selection output pulse (in accordance with the locus of the recording track and head 3 on the tape 1 R) portion is larger than the signal detected at the polling edge (P) portion. At this time, the capstan motor 15 is determined to rotate in a direction in which the CTL signal detected by the CTL head 17 decreases.

On the contrary, when the CTL signal reproduced through the CTL head 17 is positioned at the rear end as compared with the preset position, the rising edge R of the video head selection output pulse according to the trajectory of the head 3 on the tape 1 ) Portion is smaller than the signal detected at the polling edge (P) portion. In this case, the capstan motor 15 is determined to rotate in the direction in which the CTL signal detected by the CTL head 17 increases (operation 107). In step 107, the magnetic recording and reproducing apparatus is in the still picture mode until the rotation direction is determined, so that the video signal output through the video head 3 is muted.

When the rotation direction of the capstan motor 15 is determined by performing such an operation, the microcomputer 11 switches from the still image mode to the reproduction mode (step 109). Since the switching to the reproduction mode is performed immediately by the control signal of the microcomputer 11, the switching of the reproduction modes is performed in a very short time.

Then, the CTL signal is continuously reproduced and applied to the capstan motor driving unit 13 so that the capstan motor 15 rotates in the rotation direction determined in step 107, and based on the signal, (13) controls the capstan motor (15).

When the capstan motor 15 is rotated, the running of the tape 1 is carried out, so that the video envelope signal detected through the video head 3 is detected while being changed. The video envelope signal is detected through the video head 3, the amplifier 5, the envelope detector 7 and the low-pass filter 9 and input to the microcomputer 11. In the microcomputer 11, And the maximum video envelope signal is detected by continuously performing the operation of comparing the changing video envelope signal with the value of one frame before the rotation of the capstan motor in one direction according to the determined rotation direction.

The detection of the maximum value of the video envelope signal continues until the signal detected in the one-directional rotation state of the capstan motor 15 is switched from the maximum value to the decreasing value. Consequently, with the video envelope signal of the maximum value as the tracking control data, The phase control of the phase shifter 15 is performed (Step 111).

The description so far has determined the rotation direction of the capstan motor by comparing the voltage value at the rising edge of the rising edge of the video envelope signal detected through the video head 3 with the voltage value at the falling edge.

However, in order to determine the rotation direction of the capstan motor, the position of the noise signal detected in synchronism with the synchronizing signal in the still picture mode is determined. When the noise signal is located at the rising edge, It is also possible to determine the direction of rotation of the capstan motor in the direction in which the CTL signal increases. That is, the determination of the rotation direction by detecting the noise signal is relatively as compared with the detection of the high-frequency signal through the video head.

As described above, in the automatic tracking control method according to the embodiment of the present invention, tracking control is performed by checking overlapping portions of a head and a recording track with a small head width in the still image mode state before the start of the reproduction mode, The required time can be shortened to at least 1/2 or less.

In addition, since the operation until the rotation direction is determined is performed in the still-picture mode, the signal output through the screen is muted, so that the unnecessary signal is prevented from being output, There is an advantage.

Claims (3)

A second step of determining a tracking control direction based on a video envelope detection value detected according to forward and backward rotation of the video head in a still image mode in a still image mode; And a third step of switching to a playback mode when the tracking control direction is determined, thereby performing tracking in the determined bare direction. The automatic tracking control method according to claim 1, wherein the video envelope detection value of the second stage is a voltage comparison value at a rising edge and a falling edge. The method according to any one of claims 1 to 3, wherein the video signal reproduced through the video head during the first and second steps is muted.