KR0176591B1 - Noise bar elimination method in fast search mode in the reverse direction - Google Patents

Abstract

The present invention relates to a method for improving image quality for reducing noise during reverse fast search of a video signal by VTIAL.

The present invention is a capstan control process for performing a reverse high-speed search mode confirmation process for confirming mode input, and a control for advancing the traveling speed of the tape in a reverse direction at a predetermined double speed when it is determined that the reverse high-speed search is input. Drum control to change the rotational speed of the drum when it is determined that the reverse high-speed search is inputted so that the angle of the composite vector component of the drum rotational speed and the tape running speed is 180 ° different from the angle in the normal playback mode. The image signal storage process of storing the video signal read and reproduced from the tape by the video head controlled by the drum control process, and reading the digital image signal stored in the image signal storage process in the reverse order. Image signal editing output for outputting a digital image signal edited at a predetermined double speed; , The edited digital video signal, characterized in that it comprises an analog transformation process to the output is converted into an analog signal.

According to the present invention, by changing and controlling the rotational speed and the rotational angle of the drum which determine the traveling angle when the reverse high-speed search mode is executed, the digital signal editing control can be performed, whereby a clean screen without noise bars can be viewed.

Description

Noise Bar Rejection in Reverse Fast Search Mode

1 is a flowchart of a method for removing noise bars in the reverse fast search mode according to the present invention.

2 is a tape pattern diagram showing the progress of the video head in the reverse fast search mode in the conventional VTIAL.

3A to 3C are vector diagrams showing travel angles depending on the traveling speed of the tape and the rotational speed of the drum.

The present invention relates to a method for improving image quality in a special playback mode of a video reproducing apparatus, and more particularly, to a method for removing noise bars in a reverse fast search mode for reducing noise during reverse fast search of a video signal by VTIAL. It is about.

In general, in VTIAL, the gap of the video head is not set at right angles to the cross section of the head but is inclined at a constant angle so that the gap of the video head is set to have a constant angle with the gap of the head and the video track recording surface of the tape. This is called an AZIMUTH angle. .

In VHS type VTIAL, the azimuth angle is defined as 6 ° and the two video heads have azimuth angles in opposite directions. This is to prevent the head of each channel from reading the signal of the track of the adjacent field when tracing off the track of the desired field of the video track of the tape.

In normal play mode, the two video heads attached to the drum assembly record the pattern in which the signals of the respective fields of the video tracks of the video tape are recorded, and the rotation speed and tape travel of the drum with the video heads under the control of the drum motor and the capstan motor. The traveling angle by speed causes the video head to read the recorded signal as it travels through the video track on the tape. Therefore, no noise bar is generated because each video head tracks its own track by the standardized driving angle.

However, if the special playback of the reverse high-speed search function is executed in order to search for the signal recorded on the tape in high speed in the reverse direction, the running angle according to the rotational speed of the drum and the tape running speed is almost unchanged. Because the driving direction and speed of the camera change greatly, the video head cannot drive only its own track, but instead drive several adjacent tracks. By forming the noise bar.

The reason why the noise bar is generated at the above high speed reproduction will be described with reference to FIG.

When the reverse high-speed search function is executed, the video head is changed in normal playback mode because the running direction of the tape is changed 180 ° relative to the normal playback mode and the speed is relatively increased without changing the rotational speed of the drum with the video head attached. When the channel 1 head plays the channel 2 track in which the field video signal is recorded because the traveling angle of the tape moving video tape changes, the azimuth angle acts as a noise component in the hatched portion of FIG. do.

Therefore, in the conventional VTial, when the reverse high-speed search function is executed, there is a problem in that a noise bar is generated on the screen because the change of the driving angle due to the relative speed between the rotational speed of the drum and the traveling speed of the tape cannot be compensated.

Accordingly, an object of the present invention is to compensate for the difference in the running angle between the video head and the tape by changing the rotation angle and rotation speed of the drum that rotates the video head when performing the reverse high-speed search function to solve the above problems The present invention provides a method for removing noise bars in a reverse fast search mode.

In order to achieve the above object, the noise bar removing method in the reverse fast search mode according to the present invention is a reverse fast search mode confirmation process for confirming whether a reverse fast search mode is input by a user, and confirms the reverse fast search mode. Confirmation result of the capstan control process for performing control for advancing the traveling speed of the tape at a predetermined double speed in the reverse direction when it is determined that the reverse high speed search is input as a result of the checking of the process, and confirming the reverse high speed search mode confirmation process When it is determined that the reverse high-speed search is input, the drum control process of changing the rotational speed of the drum to control the angle of the composite vector component of the drum rotational speed and the tape traveling speed by 180 ° from the angle in the normal playback mode. A video attached to the drum controlled by the drum control process A video signal storage process for storing a video signal read and reproduced from a tape, and reading the digital image signal stored in the image signal storage process in the reverse order when the image signal is stored and outputting the edited digital image signal at a predetermined double speed. And an analog conversion process of converting and outputting a digital image signal output by the image signal editing output process to an analog signal, thereby eliminating noise bars on the screen in the reverse high-speed search mode. .

The drum control process converts the rotational direction of the drum in the opposite direction to that in the normal playback mode, and then increases the rotational speed and changes the rotational angle of the drum to change the angle of the composite vector component of the drum speed and the tape travel speed in the normal playback mode. It is effective to control it by 180 ° from the angle at.

It is effective to add a tracking process to maintain the maximum amplitude while comparing the envelope of the frequency modulated signal read into the video head to the drum control process.

In the drum control process, the rotational angle and the rotational speed of the drum are preset and changed according to the set reverse high-speed search mode, and the detailed adjustment of the angle of the composite vector component of the rotational speed of the drum and the traveling speed of the tape is performed by an external tracking adjustment terminal. It is effective to eliminate the noise bar by controlling the speed of the tape.

In the image signal storage process, it is effective to designate and store image signals in frame units.

In the image signal editing output process, the image signals stored in frame units are skipped and read in the reverse order of the input by skipping the number of frames corresponding to the double speed of the predetermined reverse fast search mode, and editing at the double speed of the reverse fast search mode. Is effective.

In the capstan control process, it is effective to control the speed of the tape by shortening the period of the control signal to one times the predetermined double speed of the reverse search mode as compared with the normal playback mode.

The capstan control process uses a magnetic element attached to the capstan motor to control the speed of the tape by shortening the period of a pulse generated by detecting it at a rotation to one times the predetermined speed in the reverse search mode compared to the normal playback mode. It is effective.

In the image signal editing output process, it is effective to edit and output the stored image until the converted mode becomes stable at the time of mode switching from another mode to the reverse high-speed search mode.

In the image signal editing output process, it is effective to edit and output the stored image until the converted mode becomes stable at the time of mode switching from the reverse high speed search mode to the other mode.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a flowchart of a method for removing noise bars in the reverse fast search mode according to the present invention.

In the present inventors, the method for removing the noise bar in the reverse fast search mode includes a reverse fast search mode input checking process 1010 for checking whether the reverse fast search mode is input, and a rotation direction control process for reversing the rotation direction of the drum. 1020, a capstan control process 1030 for driving the tape at a double speed set in the reverse direction, a drum for controlling the speed and rotation angle of the drum to maintain an equal inversion by 180 ° compared to the running angle in the normal regeneration mode Control process 1040, tracking control process 1050 in which the video head controls the Capstan motor to drive the field track of its own channel of the video track, and the reverse direction comparing whether the current mode continues to maintain the reverse search mode. High speed search mode maintenance check process (1060), the mode of controlling the rotation speed and rotation angle of the drum and the running speed of the capstan in the converted mode The transition process 1070, the counter operation process 1080 for operating the counter when the reverse fast search mode is input, the counter comparison process 1090 for comparing the set value of the settling time of the initial mode conversion and the counter value, A storage image signal output process 1100 for outputting an image signal in a frame unit, a digital transformation process 1110 for converting an analog video signal into a digital signal, an image signal storage process 1120 for encoding and storing a digital signal, and an image signal And an image signal editing output process 1130 for editing the data at a double speed set in the reverse direction, and an analog conversion process 1140 for converting the digital signal into an analog signal.

The reverse fast search mode input check process 1010 determines whether the reverse fast search mode is input by the user. If the reverse fast search mode is not input by the user, it is continuously checked whether the reverse fast search mode is input.

If the reverse high-speed search mode is input, the rotation direction control process 1020 of the drum is executed.

The rotation direction control process 1020 of the drum executes a function of inverting the rotation direction of the drum when it is determined that the reverse fast search mode is input. That is, in order to reverse the rotational direction of the drum by 180 ° compared with the rotational direction of the drum in the normal regeneration mode, first stop the drum, and then in the reverse direction in the normal forward fast search mode, Rotate the drum at equal speed.

A capstan control process 1030 is performed to control the speed of the tape as well as the rotation direction control process 1020 of the drum.

The capstan control process 1030 executes a control to drive the tape at a double speed set in the reverse direction as compared with the normal playback mode.

An embodiment of realizing this process is to read the control signal recorded on the control track of the tape and reduce the period of the control signal of the capstan motor by one-times the speed set in the reverse direction as compared with the normal playback mode. You can implement it in a controlled way.

Another embodiment of realizing this process is a double speed set in the reverse direction by comparing the period of the capstan pulse signal generated according to the rotation of the capstan motor by the magnetic element sensing the rotation of the capstan motor, compared with the normal regeneration mode. It can be implemented by controlling the driving voltage of the capstan motor to be reduced to one third.

Rotate the drum in the reverse direction as above, run the tape at the double speed set in the reverse direction, and then control the running angle, which is the difference in the angle at which the video head attached to the drum travels relative to the tape's running. The control process 1040 is executed.

The drum control process 1040 controls the rotational speed and the rotational direction of the drum such that the driving angle in the reverse high-speed search mode has a difference of 180 ° compared to the driving angle in the normal regeneration mode.

The drum control process 110 will be described in detail with reference to FIGS. 3a to 3c.

FIG. 3A shows the running speed of the tape and the rotational speed of the drum in a vector in the normal playback mode, and θ represents the running angle.

3B shows the case where the solid arrow vector component is in the normal reproduction mode, and the arrow component vector indicated by the dashed-dotted line represents the velocity component of the drum and the tape in the reverse fast search mode as a vector.

The running angle indicating the angle of the composite vector component of the rotational speed of the drum and the tape running speed in the normal reproducing mode is θ. If the running speed of the tape is increased in the reverse direction compared to the normal reproducing mode without changing the rotational speed of the drum in the reverse high speed search mode, the running angle θ is changed.

Therefore, when the rotational speed of the drum is increased to the arrow indicated by the dashed-dotted line in the reverse high-speed search mode, the driving angle can maintain θ reversed by 180 ° compared to the normal regeneration mode.

3C illustrates a method of controlling the running angle while simultaneously changing the rotational speed of the drum while changing the rotational speed of the drum.

The vector component indicated by solid lines in FIG. 3C shows the rotational speed of the drum in the normal reproducing mode and the driving angle θ according to the tape speed, and the vector component indicated by the dashed dashed lines indicates the rotational speed of the drum in the fast search mode and The driving angle at the time of changing the rotation angle is shown.

In the high-speed search mode described in FIG. 3b, unlike the change in the rotational speed of the drum alone, the change in the rotational speed of the drum while changing the rotational speed of the drum is compared with the rotational speed of the drum shown in FIG. Since the driving angle θ can be kept constant at a relatively low speed, the burden of increasing the speed of the drum motor can be reduced, and thus, the driving angle can be controlled even in a faster search mode.

After the drum control process 1040 is executed, the tracking control process 1050 is executed.

The tracking control process 1050 adjusts the rotation speed and rotation angle of the drum determined according to the initial value in the drum control process 1040 above, and then, after sampling the frequency modulated signal read into the video head, sums the sampled signals. The maximum speed of the tape and the rotational speed of the drum are finely controlled to increase the signal-to-noise ratio.

After executing the tracking control process 1050, a reverse fast search mode maintenance check process 1060 is performed to compare whether the current mode continues to maintain the reverse search mode.

As a result of confirming the reverse fast search mode maintenance check process 1060, if the reverse fast search mode is continuously maintained, the above tracking control process 1050 is repeatedly performed.

In this case, the digital conversion process 1110 belonging to the video control process is executed. The digital conversion process 1110 will be described in the video control process.

If an input mode other than the reverse fast search mode is confirmed as a result of the checking of the reverse fast search mode maintenance check process 1060, a mode transition process 1070 for controlling the drum and the capstan motor is performed in the checked mode. .

In parallel with the above driving control of the drum and capstan, the following video control process is executed.

As a result of the reverse fast search mode input check process 1010, when the input of the reverse fast search mode is confirmed, the counter operation process 1080 is executed to operate the counter.

After the counter is operated, a counter comparison process 1090 for comparing a counter value with a setting value of time for compensating for instability of the screen due to instability of the driving control at the beginning of mode switching is performed.

As a result of the counter comparison process 1090, when the value of the counter is smaller than the set value which is the settling time of the initial mode change, the stored image signal output process 1100 is executed.

That is, during the stabilization time at the beginning of the mode change, the image signal stored in the image memory means is output. Therefore, if the video signal stored in frame unit in the normal playback mode is edited and outputted in the reverse fast search mode during the stabilization time, the instability of the initial screen transition can be compensated.

As a result of the counter comparison process 1090, when the value of the counter is greater than the set value of the initial set time of the mode change, the instability of the initial run control according to the mode change is eliminated and it is determined that the stable run control is executed in the reverse high speed search mode. In this case, the digital conversion process 1110 is executed.

The digital conversion process 1110 executes a function of converting the demodulated analog signal into a digital signal after the video head attached to the drum reads the video signal recorded on the tape while executing driving control in a stable reverse fast search mode. do.

The digitally converted video signal is encoded in the image signal storage process 1120 and stored in the image memory.

As a method of storing an encoded video signal in an image memory, an address to be stored in units of frames can be designated and stored.

The video signal stored in the image signal storing process 1120 is edited and output as a video signal of a double speed set in the reverse direction in the constant image signal editing output process 1130.

In this process, the image signals stored in frame units are skipped and the number of frames corresponding to the double speed of the reverse fast search mode is read in the reverse order of the input, and edited at the double speed of the reverse fast search mode. It has the same effect as outputting a video signal loaded on a tape with a driving angle equal to the angle.

The video output signal edited in the image signal editing output process 1130 is converted into an analog video signal in the analog conversion process 1140 and output and reproduced on the screen so that the user can see a clean screen without noise bars in the reverse high-speed search mode. have.

If the reverse fast search mode maintenance check process 1060 is performed after the analog conversion process 1140 is performed to maintain the reverse fast search mode, the digital conversion process 1110 is performed to perform image editing in the reverse direction. Will continue to run.

If the mode is changed, the driving control and the video control are executed in the converted mode in the mode transition process 1070.

Even in this case, in order to output a stable screen at the beginning of mode conversion, the image stored in the memory means is edited and output only during the stable time.

As described above, according to the present invention, by changing and controlling the rotational speed and the rotational angle of the drum which determine the travel angle at the time of executing the reverse high-speed search mode, and executing the digital signal signal editing control, a clean screen without noise bars can be viewed. It has an effect.

Claims (10)

A reverse fast search mode checking step of confirming whether a reverse fast search mode is input by a user; A capstan control process of controlling to advance the traveling speed of the tape at a predetermined double speed in the reverse direction when it is determined that the reverse high speed search is input as a result of the checking of the reverse high speed search mode confirmation process; When it is determined that the reverse high-speed search mode is input, it is determined that the rotational speed of the drum is changed so that the angle of the composite vector component of the drum rotational speed and the tape running speed is determined in the normal playback mode. A drum control process of controlling a difference of 180 ° with the drum; An image signal storing step of storing a video signal read and reproduced from a tape by a video head attached to a drum controlled by the drum control step; An image signal editing output process of reading out the digital image signal stored in the image signal storing process in the reverse order when it is stored and outputting the edited digital image signal at a predetermined double speed; And an analog conversion process of converting the digital image signal output by the image signal editing output process into an analog signal and outputting the analog signal to eliminate noise bars on the screen in the reverse high-speed search mode. How to remove the noise bar. The method of claim 1, wherein the drum control process comprises changing the rotational speed of the drum and the rotational angle of the drum after converting the rotational direction of the drum to the opposite direction in the normal regeneration mode. The noise bar removal method in the reverse high-speed search mode, characterized in that the control to control the angle of to have a 180 ° difference from the angle in the normal playback mode. The noise bar of claim 1, wherein the drum control process comprises adding a tracking process for maintaining the maximum amplitude while comparing the envelope of the frequency-modulated signal read by the video head. How to remove. The drum control process of claim 1, wherein the drum control process is performed by changing a drum rotation speed and a rotation speed in advance according to the set reverse high-speed search mode, and further adjusting the angle of the composite vector component of the drum rotation speed and the tape running speed. Noise bar removal method in the reverse fast search mode, characterized in that the noise bar is removed by controlling the speed of the tape by an external tracking adjustment terminal. 2. The method of claim 1, wherein the image signal is stored in an address unit in a frame unit in the image signal storage process. The reverse high-speed search according to claim 1, wherein the image signal editing output process skips a number of frames corresponding to a double speed of a predetermined reverse fast search mode and reads the image signal stored in a frame unit in reverse order of input. A method for removing noise bars in a reverse high-speed search mode, characterized by editing at a mode double speed. The reverse fast search mode according to claim 1, wherein the capstan control process controls the speed of the tape by shortening the period of the control signal to one times the predetermined double speed of the reverse search mode compared to the normal playback mode. How to remove noise bars in The method of claim 1, wherein the capstan control process uses a magnetic element attached to the capstan motor to shorten the period of the pulse generated by the detection to one times the predetermined speed in the reverse search mode compared to the normal regeneration mode. Removing the noise bar in the reverse high-speed search mode. The reverse high speed editing process according to claim 1, wherein the image signal editing output process edits and outputs the stored image until the converted mode is stabilized when the mode is switched from another mode to the reverse high speed search mode. How to remove the noise bar in search mode. The reverse high speed editing process according to claim 1, wherein the image signal editing output process edits and outputs a stored image until the converted mode becomes stable at the time of mode switching from the reverse high speed search mode to the other mode. How to remove the noise bar in search mode.