JPH04302839A - Automatic tracking control circuit and control method thereof - Google Patents

Abstract

PURPOSE: To reduce a noise component displayed on a screen at the time of the slow travel of a tape by controlling a system so that stopped time becomes time when the sizes of right and left DC components of a video signal become equal at the time of a slow operation. CONSTITUTION: A signal outputted through a servo motor 1 is amplified by a preamplifier 2 and the signal amplified by the preamplifier 2 is amplified and outputted by the video signal detected by an amplifier 3. The video signal amplified by the circuit 3 is applied to a shaping circuit 4 and the DC component is detected. The DC component of the video signal outputted here is shaped and it is applied to a micro computer 5. The micro computer 5 compares the sizes of the right/left sides of the input DC component by a reference signal REF from outside and tracking data for controlling the sizes of the right/left sides to be equal is outputted. On the other hand, slow tracking data outputted from the micro computer 5 is applied to a drive circuit 6 and a motor 1 is controlled by slow tracking data.

Description

[Detailed description of the invention]

0001

[Industrial Field of Application] The present invention relates to a video tape recorder or a video camera capable of image processing, and in particular to high image quality by minimizing noise components caused by errors in the point at which the tape is stopped when the video tape is running slowly. The present invention relates to an automatic tracking control circuit and its control that can obtain the following.

0002

2. Description of the Related Art In general, the slowdown operation of a video tape recorder involves repeatedly running and stopping the tape at high speed in response to a control signal input from the outside. That is, when the control signal is input from the outside, the control signal is applied to the capstan motor so that one frame of the video signal runs at high speed, and after the frame video signal runs, the high speed run is stopped. The rotating capstan motor is reversed. Then, when the capstan motor rotates in the reverse direction to completely stop, the motor is rotated in the forward direction again to completely stop the tape.

[0003] By repeating the above process, the video tape recorder is slowed down. At this time, noise components are displayed at the top and bottom of the screen depending on when the capstan motor is stopped. That is, (a
), if the magnitude of the envelope of the input video signal is the same in the 5 msec region of the rising and falling portions of the slow drive pulse P, no noise component will be shown on the screen, but
As shown in (b) of Figure 1, the size of the envelope is larger on the left side than on the right side, so the noise component appears at the top of the screen.
As shown in (c), since the size of the envelope is smaller on the left side than on the right side, there is a problem in that the noise component appears at the bottom of the screen.

0004

SUMMARY OF THE INVENTION The present invention is intended to solve these problems, and an object of the present invention is to improve the magnitude of the envelope input between the rising and falling portions of the creep drive pulse. After comparing the values, the capstan motor is controlled by resetting the position where the tape is stopped, thereby minimizing the noise components displayed on the screen when the tape is running slowly and obtaining high image quality. An object of the present invention is to provide an automatic tracking control circuit and a control method therefor.

[0005]

[Means for Solving the Problems] A feature of the present invention for achieving the above object is that a servo motor and a capstan motor run at high speed according to the size of an input envelope and a control signal to generate one frame of video. In a video tape recorder in which the running tape is stopped after the signal is moved and slow running is performed, a preamplifier for amplifying the signal output from the servo motor is connected to the output side of the preamplifier. an amplifier circuit for amplifying a video signal from the amplified signal; a shaping circuit connected to the output side of the amplifier circuit for shaping an envelope that is a direct current component of the amplified video signal; and the shaping circuit. A microcomputer is connected to the output side of the microcomputer and outputs a control signal that controls the left and right sides of the signal to be the same after comparing the magnitudes of the left and right signals shaped by a reference signal input from the outside, and the microcomputer described above. The automatic tracking control circuit includes a servo motor and a drive circuit that is connected to the output side and drives a servo motor and a control circuit using slow tracking data output from a microcomputer.

Another feature of the present invention is that the servo motor and capstan motor are driven at high speed according to the size of the input envelope and the control signal, and one frame of video signal is moved. After comparing the sizes of the envelopes, the running tape is stopped so that the envelopes have the same size.In the automatic transistor control circuit of the video tape recorder, the sizes of the left and right sides of the input envelope are detected. a signal detection routine that is temporarily stored in the signal detection routine; and a correction signal selection process in which the signals stored by the signal detection routine are compared and a signal whose left and right deviations are corrected from the compared signals is selected; and a correction in which slow tracking data is corrected and output by the correction signal selected in the correction signal selection process.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

FIG. 2 is a block diagram showing an automatic tracking control circuit for a video tape recorder according to the present invention, which includes a servo motor 1, a preamplifier 2, an amplifier circuit 3, a shaping circuit 4,
It consists of a microcomputer 5 and a drive 6. That is, a preamplifier 2 for amplifying a detected signal is connected to the output side of the servo motor 1, and an amplifier circuit 3 for outputting a detected video signal is connected to the output side of the preamplifier 2. be done. Further, a shaping circuit 4 is connected to the output side of the amplifier circuit 3, which detects and then shapes the envelope, which is the DC component of the amplified video signal. A microcomputer 5 is connected to the microcomputer 5, which outputs creeping tracking data in which the DC components are corrected to be the same after comparing the magnitudes of the left and right sides. A drive circuit 6 is connected to the output side of the microcomputer 5 and is controlled to drive a servo motor based on creep tracking data output from the microcomputer 5.

FIG. 3 is a flow chart showing an automatic tracking control method for a video tape recorder according to the present invention.
The order is: signal detection routine L1, correction signal selection process P1, and correction process P2. Here, the signal detection routine L1
includes a determination step S1 for determining whether the tape is stopped after moving one frame of the video signal, and the above-mentioned determination step S1.
If it is determined that the tape has been stopped, the magnitude of the envelope, which is the DC component of the input video signal, of the rising and falling portions of the slow drive pulse P is input and stored in steps S2 to S5. There is. In addition, in the correction signal selection process P1, the two signals outputted and stored from the signal detection routine L1 are compared, and if the left side is larger than the right side, a flag is set to 1, and the left side is A comparison routine L2 in which a flag is set to 0 if it is smaller than the right side, and the above comparison routine L2.
If the compared magnitude is 2 msec or more, a correction signal is output so that the deviation is corrected by 2 msec, and if the compared magnitude is 1.5 msec, a correction signal is output.
A correction signal is output so that a deviation of msec is corrected, and when a change of 1 msec occurs in the compared signal, a correction signal that corrects this deviation is output, and at this time, if the compared signal is within 1 msec. The sequence is the correction signal selection routine L3 in which a correction signal is output so as to be corrected every 0.5 msec.

The correction process P2 includes a determination step S16 in which the setting state of the flag is determined in step S6 of the comparison routine L2, and a determination step S
When the flag is set to 1 in Step 16, the slow tracking data of the correction signal selected in the correction signal selection routine L3 is increased, and the above-mentioned determination step S
If the flag is set to 0 in step S16, the correction signal selection routine L3 performs control such that the slow tracking data of the correction signal selected by the correction signal is output to the servo motor.

In the present invention configured as described above, a signal outputted through the servo motor 1 shown in FIG. The detected video signal is amplified and output. The video signal amplified by the amplifier circuit 3 is applied to a shaping circuit 4, where the DC component of the input video signal is detected, and the DC component of the video signal outputted here is shaped and applied to the microcomputer 5. Ru. The microcomputer 5 compares the magnitude of the DC component input with a reference signal input from the outside, and outputs slow tracking data corrected from the compared signals. On the other hand, the slow tracking data output from the microcomputer 5 is applied to the drive circuit 6, and the servo motor is controlled by the slow tracking data.

To explain the above process in more detail with reference to FIG. 3, the magnitude of the left and right sides of the DC component of the video signal output from the above-mentioned shaping circuit 4 of FIG. 2 is detected in steps S2 and S4; The detected magnitude is temporarily stored in steps S3 and S5 of the signal detection routine L1. Then, steps S3 and S5 of the signal detection routine L1
The magnitudes of the left and right sides of the DC component stored are compared in the determination step S6 of the comparison routine L2, and if the magnitude of the compared left side is larger than the magnitude of the right side, a flag is set in step S7 of the comparison routine L2. is set to 0, and if the size of the compared left side is smaller than the size of the right side, step S of comparison routine L2
8 sets the flag to 1. Then, in the determination step S9 of the correction signal selection routine L3, it is determined whether the difference between the compared left and right sizes is 2 msec, and if the compared left and right sizes are 2 msec, the correction signal selection routine A correction signal is selected at 2 msec in step S10 of L3. However, if it is determined in the determination step S9 that the left and right side sizes are not 2 msec, the difference in the left and right sizes compared in the determination step S11 of the correction signal selection routine L3 is 1.
．． 5 msec, and if the difference in size between the left and right sides compared here is 1.5 msec, step S12 of the correction signal selection routine L3 determines that the correction signal is 1.5 msec.
It is selected in 5 msec.

[0013] Furthermore, according to the determination step S11 of the correction signal selection routine L3, the difference in size between the left and right sides is 1.5 m.
If it is determined that it is not 1.0 ms, it is determined in determination step S13 of correction signal selection routine L3 whether it is 1.0 msec, and 1.0 ms is determined in determination step S13.
If it is determined that it is ec, a correction signal is selected at 1.0 msec in step S14. However, if it is determined that the difference compared in step S13 is not 1.0 msec, step S15 determines that the difference is 0.5 msec.
Correction is selected in c.

As mentioned above, the correction signal is 2.0 msec,
After one of 1.5 msec and 1.0 msec is selected, the flag is set to 1 in the determination step S16 of the correction process P2.
If the flag is determined to be 1, the correction signal selected from the correction signal selection routine L3 is incremented and outputted in step S17 of the correction process P2, while the flag is set in step S16. If it is determined that 1 is not set, the correction signal selected from the correction signal selection routine L3 is subtracted and outputted in step S18 of the correction process P2. The creeping tracking data output in steps S17 and S18 is applied to the servo motor 1 in step S19 of the correction process P2, and the servo motor 1 is controlled by the applied creeping tracking data.

[0015]

[Effects of the Invention] As described above, in the present invention, the magnitudes of the left and right DC components of the input video signals are compared, and the slow tracking data corrected by the deviation of the compared signals is applied to the servo motor. By controlling the time point at which the slow-down operation is stopped to be the point at which the left and right magnitudes of the DC component of the video signal are the same, the noise component shown on the screen during the slow-down operation is slowed down and high image quality is obtained. effective.

[Brief explanation of drawings]

FIG. 1 is a state diagram showing a screen of a general video tape recorder in a state where tracking is stopped during slow movement.

FIG. 2 is a block diagram illustrating an automatic tracking control circuit according to the present invention.

FIG. 3 is a flowchart illustrating an automatic tracking control method according to the present invention.

[Explanation of symbols]

1 Servo motor 2 Preamplifier 3 Amplification circuit 4 Shaping circuit 5. Microcomputer 6 Drive circuit REF Reference signal P1, P2 process L1-L3 Routine S1~S19 Step ST Start step RET Return step P Slow drive pulse

Claims (4)

[Claims] Claim 1: According to the input envelope size and control signal, the servo motor 1 and the capstan motor run at high speed, and after one frame of video signal is moved, the running tape is stopped and slow running is performed. In a video tape recorder, a preamplifier 2 amplifies a signal output from the servo motor 1, and an amplifier circuit connected to the output side of the preamplifier 2 and amplifies a video signal from the amplified signal. 3, a shaping circuit 4 connected to the output side of the amplification circuit 3 to shape the envelope, which is the direct current component of the amplified video signal; A microcomputer 5 is connected to the output side of the microcomputer 5 and is output from the microcomputer 5, which outputs a control signal that has the same magnitude after comparing the left and right sides of the signal shaped by the reference signal REF. An automatic tracking control circuit consisting of a servo motor and a drive circuit 6 that drives a control circuit based on slow tracking data. [Claim 2] After the servo motor and capstan motor are run at high speed according to the size of the input envelope and the control signal, one frame of video signal is moved, and the sizes of the left and right sides of the input envelope are compared. In the automatic tracking control circuit of a video tape recorder, where the running tape is stopped so that the envelopes have the same size, the left and right sizes of the input envelope are detected and temporarily stored.Signal detection a correction signal selection process P1 in which signals stored in the signal detection routine L1 are compared and a signal whose left and right deviations are corrected from the compared signals is selected; and the correction signal selection step P1. An automatic tracking control method for a video tape recorder comprising a correction step P2 in which slow tracking data is corrected and outputted using a correction signal selected in step P1. 3. The correction signal selection process P1 includes a comparison routine L2 in which the left and right sizes stored by the signal detection routine L1 are compared and a flag is set according to the compared signals; 3. The automatic tracking control method according to claim 2, further comprising a correction signal selection routine L3 in which a correction signal is selected based on the difference in size between left and right sides after the flag is set. 4. The correction process P2 includes a determination step S16 for determining whether the flag is set to 1;
If the flag is set to 1 in the above determination step S16, the correction signal is increased in step S1.
7, a step S18 in which the selected correction signal is decreased when the flag is set to 0 in the above-described determination step S16, and a step in which the slow tracking data increased or decreased in the above-mentioned steps S17 and S18 is output. 3. The tracking control method according to claim 2, further comprising step S19.