KR930001150B1 - Tracking control method for vtr - Google Patents

Abstract

The DC component of envelope curve signal of video signal detected by a head is analyzed to determine a position of a head from which a maximum DC component is detected. The method comprises an interrupt process (P1) for controlling running speed of a tape slowly when head switch control pulse (HSP) is high, a forward direction control process (P2) for controlling rotating direction of a capstern mortor in forward direction by generating acceleration control signal (HP) and on/off control signal (COPF), a stopping process (P3) for stopping a capstern motor by providing reverse rotating signal and a stop position control process (P4) for stopping a stop position of a tape at a preset position.

Description

Tracking control method of video tape recorder

1 is a block diagram showing a tracking control system of a general video tape recorder.

2 is an operation timing diagram of a tracking control system of a general video tape recorder.

3 and 4 are state diagrams showing a stationary tracking control system of a conventional video tape recorder.

5A, 5B, and 5C are flowcharts illustrating a tracking control method of a video tape recorder according to the present invention.

* Explanation of symbols for main parts of the drawings

1: Preamplifier 2: Micom

3: servomotor 4: capstan motor

CP: Control Signal HSP: Head Switch Pulse

HP: Acceleration Control Signal

CFRP: Capstan motor reverse / forward control signal

COFP: Capstan motor on / off control signal

t1 ~ t5, tr: time P1 ~ P4: process

S1 ~ S27: step

The present invention relates to a video tape recorder (Video Tape Recorder) or a video cassette tape recorder (Video Casette Tape Recorder), and more particularly, to a video tape recorder capable of automatically controlling tracks when the video tape recorder runs slowly. A tracking control method.

In general, a tracking control system of a video tape recorder includes an envelope of a video screen output by the preamplifier 1 of the video tape recorder and a control pulse inputted from the outside to determine the noise state of the video signal. The microcomputer 2 is driven by the CP and the head switch control pulse HSP, and the servo motor 3 and the capstan motor 4 are controlled by the control signal output from the microcomputer 2. In this case, when the video tape recorder travels slowly, the capstan motor rotates at a high speed forward rotation and stops.

That is, as shown in FIG. 2, after t1 hours when the head switch control pulse HSP becomes a high signal, the microcomputer 2 outputs a control signal for high speed forward rotation of the capstan motor for t2 hours, and records the signal. After one frame of information has been moved, the microcomputer 2 outputs a control signal for tr time to stop the inertia of the high speed forward rotation of the capstan motor. In addition, the capstan motor 4 is stopped by the control signal of the microcomputer 2 for a time t3, and the reverse of the capstan motor 4 in which the capstan motor 4 is rotated in reverse to stop the high speed forward rotational inertia of the capstan motor 4. A control signal is output for t4 to stop the rotational inertia and stop the tape completely. Slow driving is performed by moving one frame at a high speed of the capstan motor and then stopping.

The process will be described in more detail. If the head switch control pulse HSP is detected as high signal from the microcomputer 2 of FIG. 1, the tape moves after the time t1 of FIG. At this time, the capstan motor on / off control signal COFP is output as a high signal to control the capstan motor 4 to rotate forward, and the acceleration control signal HP is a high signal to give a strong force to the capstan motor 4. Control the tape to move in forward rotation.

When the t2 time in FIG. 2 passes, the acceleration control signal HP is outputted as a low signal by lowering the drive level of the capstan motor 4 by the servo motor 3 in FIG. 1, and at the same time, the tape moves by one frame. A control pulse indicating that the signal is detected is detected in the microcomputer 2. On the other hand, after the tr time in FIG. 2 in which the control pulse is detected in the microcomputer 2, a stop operation for stopping the tape is started, and an acceleration control signal (HP) for an instant stop of the moving tape after the tr time elapses. ) Is output as a high signal again.

In addition, the forward rotation / reverse rotation control signal CFRP of the capstan motor is output so that the capstan motor is controlled in reverse rotation, so that the forward rotation inertia of the capstan motor is suppressed. That is, the tape is driven and stopped for t3 hours in FIG. 2, and the capstan motor is driven in forward rotation again for t4 hours in FIG.

Then, after t4 hours in FIG. 2, the acceleration control signal HP is output as a low signal again, and the capstan motor on / off control signal CFRP is also output as a low signal to completely stop the rotation of the capstan motor.

The above-described process is repeatedly performed to perform a slow driving. Here, the noise is determined depending on where the tape stops. 3 is a state diagram showing a position where the tape stops, (a) shows a case where the time at which the tape is stopped (tr) is set late, and (b) shows a case where the time at which the tape is stopped (tr) is set appropriately. (C) is a case where the time tr at which the tape is stopped is quickly set.

That is, in FIG. 3A, a small number of video signals are extracted at the beginning of the head trace on the tape, and many video signals are extracted at the end of the trace. Accordingly, a clear image is displayed on the lower portion, but noise is displayed on the upper portion, and the video signal region extracted from the tape is shown in FIG.

On the other hand, in the case of Fig. 3B, the time tr is ideally set, and the region of the video signal extracted to the tape is well shown in Fig. 4B.

However, in the case of (c) of FIG. 3, a short time tr is set so that many video signals are extracted at the beginning of the head trace on the tape, but it is almost impossible to extract the video signal at the end of the trace. Do. Therefore, a clear image is displayed at the top of the lower surface, but noise is displayed at the bottom. In this case, the inverse of the video signal extracted from the tape is represented as shown in FIG.

As described above, the time at which the tape is stopped (tr) is conventionally set in advance in the first microcomputer, and when the system is unstable, there is a problem in that noise is displayed when the tape runs slowly.

The present invention has been made to solve such a problem, and an object of the present invention is to check the stop state of the tape while the tape is running in a slow motion, and to determine the time when the tape is stopped again when it is different from the set time. It is an object of the present invention to provide a tracking control method for a video tape recorder that can accurately display a point in time at which the tape is stopped, and thus display a clear screen when the tape is running slowly.

The characteristics of the present invention for achieving the above object is the envelope of the video signal output from the video preamplifier 1 of the video to know the state of the noise and the control pulse (CP) and the head switch control pulse (HSP) input from the outside. Microcomputer 2, the control signal is output by the), the capstan motor reverse / forward rotation control signal (CFRP), acceleration control signal (HP) connected to the output shaft of the microcomputer (2) output from the microcomputer (2) In the tracking control system of the servo motor 3 and the capstan motor 4 in which the capstan motor 4 is controlled by the capstan motor on / off control signal COFP and the video tape recorder, An interrupt process for controlling the tape to travel in a slow motion when the head switch control pulse input from the outside to rotate forward is a high signal; A forward rotation control process in which an acceleration control signal and a capstan moton on / off control signal are output as a high signal after the execution of the interrupt process so that the capstan motor is rotated forward; A stop control process in which the tape is stopped by rotating the capstan motor which is rotated forward after the forward rotation control process; After the stop control process is executed, the stop position of the tape running during the slow running time set by the interrupt process is examined, and the stop position is maintained as it is, if the preset position is the same. A stop position control process of resetting the position; Tracking method of a video tape recorder.

Hereinafter, with reference to the accompanying drawings an embodiment according to the present invention will be described in detail.

5 is a flowchart illustrating a tracking control method of a video tape recorder according to the present invention, wherein an interrupt process (P1) for interrupting the video tape recorder when a control signal for driving the tape in a slow motion is recognized and the interrupt process ( A forward rotation control process P2 in which the capstan motor 4 is forward rotated by the head switch control signal HSP input after the execution of P1), and a capstan motor rotated forward after the forward rotation control process P1 is executed. Stop control process (P3) that stops and stop position control process (P4) to accurately set the stop position of the capstan motor by checking whether the stop position of the capstan motor coincides with a preset position after the execution of the stop control process (P3). )

Here, the interrupt process (P1) is a determination step (S1) for discriminating whether or not the start of the difference driving is performed when the forward and stop of the tape is performed when the control signal to run the tape is running slowly, and the determination step (S1) If it is determined that the interval driving is started by the step (S2) of the forward rotation control process (P1) is set in which the time (t1) for the tape is ready to move, the gap driving is performed by the determination step (S1) The determination step (S3) for determining whether it is in the stopped state after determining that the vehicle is not started, and the time (α) at which the position of the stop can be examined when the tape is stopped by the determination step (S3). It consists of the setting step S4. That is, the DC component of the envelope output from the preamplifier 1 of FIG. 1 while being set by step S4 is inspected.

On the other hand, the determination step (S5) of the forward rotation control process (P2) for judging whether the time t1 at which the tape is moved ready is set by the step (S2) of the interrupt process (P1), and whether it has been input at this set time (t1). And the acceleration control signal HP and the capstan motor on / off control signal COFP become high signals in order to forwardly rotate the capstan motor when it is determined that the time t1 is input by the determination step S5. Step S6, the discrimination step S8 of the forward rotation control process P2 for determining whether the time t2 at which the tape is moved one frame by the output high signal is set, and the discrimination step S8. Step S9 and the step S9 in which the acceleration control signal HP is output as a high signal so that the capstan motor controlled by the servo motor of FIG. 1 is rotated forward when the time t2 is set by After that, rotate the capstan motor to Step S10 of the forward rotation control process P2 is a time at which the tape is stopped and a time at which the tape is stopped after the control signal CP is input in order to be rotated in the opposite direction to be rotated to be stopped. In order.

On the other hand, after the control signal CP is input by the step S10 of the forward rotation control process P1, the time t3 at which the tape is stopped is set again and then repeated again to determine whether the time t3 is set. If it is determined that the stop control process P3 for discriminating is set by the determination step S11 and the determination step S11, the capstan motor is controlled to stop, i.e., the capstan motor reverse rotation / forward rotation In step S12 of the stop control process P3 in which the control signal CFRP is set to a high signal, the capstan motor is reversely rotated by the set time t3 after the execution of the step S12. It consists of the step S13 of the stop control process P3 in which the time t4 when a capstan motor rotates forward is set for forward rotation.

The determination step S14 of the stop control process P3 for determining whether the time t4 is input after the time t4 is set by the step S13 and the time t4 is set, and the determination step S14. In step (3) of the stop control process (P3) in which both the acceleration control signal HP and the capstan motor on / off control signal COFP are set to high signals in order to rotate the capstan motor forward when the time t4 is inputted by (S15), and step S16 of the stop control process P3 in which the input time t5 of the head switch pulse HSP input after the execution of the step S15 is set.

If it is determined that the time t4 is not input again by the determination step S14, the stop position control process P4 determines whether or not the time? Is set by the step S4 of the interrupt process P1. The determination step S17 and the time N set by the determination step S17 are input, and the step S18 in which the time N is generated is counted. Step S19 of the stop position control process P4 in which the direct current component of the envelope of the video signal input after the execution of S18 is detected. At this time, the step S20 of the stop position control process P4 in which the DC component detected by the step S19 is stored and the time α and the stop position set by the step S4 of the interrupt P1 are stored. The determination step of the stop position control process P4 for determining whether the product of the number N counted by step S18 of the control process P4 is 16.7mesc, which is a half period of the head switch pulse input time t5 to be inputted ( When the product of the time α and the counted number N is 16.7 msec by S21 and the determination step S21, the highest value of the value stored by the step S20 of the stop position control process P4 is sampled. A determination step S22 of the stop position control process P4 for determining whether the point is halfway, and a stop position control process P4 for determining whether it is the front of the sampled point when not centered by the determination step S22. Step S23 is performed in this order. Here, the determination step S24 of the stop position control process P4 for discriminating whether or not the time tr is the highest value that can be set if it is stopped in front of the point sampled by the step S23, and the determination step S24. By the step (S25) of the stop position control process (P4) to increase the time (tα) when the value is not the maximum by the step, and is set in the case of not stopping in front of the point sampled by the step (S23) In the determination step S26 of the stop position control process P4 for determining whether the time tr is the lowest value, and in step S27 for decreasing the time tr if it is not the lowest value by the determination step S26. consist of.

On the other hand, if it is not the half period t5 / 2 of the head switch pulse HSP to which the product of the two signals α (N) is input by the determination step S21, step S4 of the interrupt process P1 is again performed. Is executed.

In this invention configured as described above, the forward rotation and the stop operation are repeatedly performed in order to drive the tape slowly. That is, when the head switch pulse HSP is input from the outside as shown in FIG. 2, the tape is ready to move for a predetermined time t1, and the tape is rotated forward for a predetermined time t2 after the tape is ready to move. After the tape is rotated forward, the capstan motor reverses rotation after the tape passes one frame according to the input control signal CP to prevent the rotation of the tape forward. Therefore, the capstan reverses for a predetermined time t3. Is rotated.

In addition, the capstan motor which is reversely rotated for a predetermined time t4 is stopped to rotate the tape again forward.

The above process will be described in detail with reference to FIG. 5. When the head switch pulse HSP of FIG. 2A is input from the outside, stop and forward rotation are performed by the determination step S1 of the interrupt process P1. After this, that is, whether the head switch pulse (HSP) inputted after the end of the differential driving or the head switch pulse inputted at the start of the differential driving is determined. The time t1 at which the tape is moved is set by step S2 of the process P1.

However, when it is determined that the head switch pulse HSP is input after the difference driving is completed by the determination step S1, the time? For checking the stop position is determined by step S4 of the interrupt process P1. Is set.

Meanwhile, after the time t1 at which the tape is ready to move is set by step S4 of the interrupt process P1, the time t1 at which the tape is ready to move by the determination step S5 of the forward rotation control process P1. ) Is inputted, and when the time t1 is inputted, the rapid control signal HP and the capstan motor, in which the capstan motor is rotated forward by the step S6 of the forward rotation control process P1, Both on / off control signals COFP are output as high signals.

Then, the time for the tape is rotated forward by the step S7 of the forward rotation control process (P2) after the signal to control the forward rotation of the capstan motor by the step (S6) of the forward rotation control process (P2) t2 is set. However, if it is determined that the time t1 at which the tape is ready to move is not input by the determination step S5 of the forward rotation control process P2, the step S9 of the forward rotation control process P2 is determined from the servo motor. The acceleration control signal HP of the capstan motor to be controlled is set to a high signal, so that the capstan motor is rotated forward so that one frame of the tape is moved. Further, after execution of the step S9, the time tr at which the control signal for rotating the capstan motor reversely rotated to output the tape is stopped and the time t3 at which the tape is stopped are set by the step S10. .

On the other hand, if it is determined that the time t2 is not input by the determination step S8 of the forward rotation control process P2, it is determined whether the time t3 at which the capstan motor is ready to stop is input. If it is determined by the determination step S11, and if it is determined that the time t3 is input, it is determined by the determination step S11 of the stop control process P3, and it is determined that the time t3 is input. When the capstan motor forward / reverse control signal CFRP is set to a high signal by step S12 of the stop control process P3, the capstan motor is reversely rotated.

Then, the time t4 for reducing the inertia of the reverse rotation of the capstan motor is set by step S13 of the stop control process P3 after the execution of the step S12.

At this time, when it is determined that the time t3 is not input by the determination step S11 of the stop control process P3, the capstan motor reversely rotated by the step S14 of the stop control process P3 is stopped again. It is determined whether the time t4 is input, and if it is determined that the time t4 is input, the acceleration control signal HP and the capstan in which the capstan motor is rotated forward by the step S15 of the stop control process P3 are determined. Both the motor on / off control signal COFP is set as a reverse signal. That is, the capstin motor is completely stopped and the tape is stopped.

However, if it is determined that the time t4 is not input by the determination step S14 of the stop control process P3, it is stopped whether the time α set by the step S4 of the interrupt process P1 is input. Judgment is made by the determination step S17 of the position control process P4, where the count N of the time α is counted. After execution of step S18, step S19 of the stop position control process P4 in which the DC component of the envelope of the input video signal is inspected is executed.

In addition, the DC component of the envelope of the video signal checked in step S19 is stored in the RAM by step S20 of the stop position control process P4.

The product of the time α input by the step S4 and the number N counted by the step S18 is the head switch pulse HSP input by the determination step S21 of the stop position control process P4. If it is determined that the half cycle (t5 / 2) of 16.7msec, and if the product of two numbers is determined to be 16.7msec, the DC component of the envelope stored by the determination step (S22) of the stop position control process (P4) is Determines whether the peak is Joule at the time of sampling.

Here, when it is determined by the determination step S22 that the DC component of the envelope is not the center of the point at which the peak is sampled, the determination is made at the time when the DC component of the envelope is sampled by the determination step S23 of the stop position control process P4. If it is determined that it is ahead of the sampled time point, it is determined whether the time tr set by the determination step S24 of the forward rotation control process P4 is the highest value that can be set.

When it is not the maximum value by the determination step S24, the time tr set by the step S25 of the stop position control process P4 is increased, and the DC component of the envelope is determined by the determination step S23. If it is determined that the maximum of is not the front of the sampled time point, it is determined whether the time tr set by the determination step S26 of the stop position control process P4 is the lowest settable value. At this time, if it is determined by the determination step S26 that it is not the lowest value, the time tr set by the step S27 of the stop position control process P4 is reduced.

On the other hand, if it is determined that the product of the time α and the counted number N is not 16.7 msec by the determination step S21 of the stop position control process P4, step S4 of the interrupt process P1. Is set again by the time tr.

As described above, the present invention examines the DC component of the envelope of the video signal output from the head after the tape is moved by one frame by the stop position control process, and determines whether the largest DC component exists in the middle of the sampled time point. Otherwise, the time when the tape stops automatically is changed, and thus, the sharpest image quality can be obtained when the tape is driven in the slow motion by making the largest part of the DC component of the envelope be the half period of the head switch pulse from the video signal. It has an effect.

Claims (2)

The microcomputer 2 in which the control signal is output by the envelope signal of the video signal output from the video preamplifier 11 of the video to know the state of the noise and the control pulse CP and the head switch control pulse HSP. Wow ; Connected to the output side of the microcomputer 2 and controlled by the capstan motor reverse rotation / forward rotation control signal (CFRP), acceleration control signal (HP), capstan motor on / off control signal (COFP) output from the microcomputer (2) A servo motor 3 and a capstan motor 4; In the tracking control system of a video tape recorder, an interrupt for controlling the tape running in a slow motion when a head switch control pulse input from an external device for forward rotation of the tape in the microcomputer 12 is a high signal. After the process P1 and the execution of the interrupt process P1, the acceleration control signal HP and the capstan motor on / off control signal COFP are outputted as high signals so that the capstan motor is rotated forward (P2). ), A stop control process (P30) in which the capstan motor which is rotated forward after the forward rotation control process (P2) is reversed, and the tape is stopped, and the interrupt process (P1) after the stop control process (P3) is executed. After checking the stop position of the tape running during the slow running time set by), if the stop position is the same as the preset position, the stop position is maintained as it is. The tracking control method of a video tape recorder other cases, consisting of a set and the stop position is reset, the stop position control process (P4) which, in order. The stop position control process P4 comprises: a determination step S17 for determining whether the input time? Set by the interrupt process P1 is input, and a determination step S17. When it is determined that time α is input, step S18 of counting the number N of the input time α and inspecting the DC component of the envelope of the video signal input after the execution of the step S18 is performed. Step S19, the step S20 in which the DC component of the envelope detected by the step S19 after the execution of the step S19 is stored, and the time α after the execution of the step S20 is counted. The determination step S21 for determining whether the product of the number N is equal to the half period t5 / 2 of the head switch pulse HSP to be input, and the product of the two numbers is determined by the determination step S21. If it is determined to be equal to the half period of, the DC component of the envelope stored by step S20 is sampled. A judging step S22 for judging whether it is the center of the point; a judging step S23 for judging whether it is in front of the center when it is determined by the judging step S22 that the DC component of the envelope is not the center of the sampled time point; In the case where it is determined by the determination step S23 that it is determined to be forward, the determination step S24 for determining whether the time tr is the highest value that can be set, and the maximum value for which the time tr can be set in the determination step S24 are If not, step S25 of increasing time tr, and determination step S26 of determining whether time tr is the lowest value that can be set when it is determined not to be in front of the sampled point by the determination step S23. And a determination step S26 for determining whether the time tr is the lowest value that can be set by the determination step S26, and a determination step S26 for determining that the time tr is not the lowest value that can be set. Time tr A step (S27) and a tracking control method for a tape recorder control bidet net consisting of.