KR960000448B1 - Screen reproducing method of vtr system - Google Patents

Abstract

waiting for the generation of head switching pulses; operating a capstan motor and waiting for one field period; performing the first and the second sampling processes of ATF error signals; analyzing the values of the first and the second samplings; replaying a still screen without operating the capstan motor when the value of the first sampling is exactly same as that of the second sampling; calculating the time difference when the value of the first sampling is larger than that of the second sampling and replaying a still screen by stopping the capstan motor; and calculating the time difference when the value of the first sampling is smaller than that of the second sampling and replaying a still screen by stopping the capstan motor.

Description

How to play screen of VTR system

1 is a system diagram for performing the present invention

2 is an operating waveform diagram of each part of FIG.

3 is a flow chart of the present invention

* Explanation of symbols for main parts of the drawings

10: microcomputer 20: ATF processing unit

30 head 40 capstan driving unit

The present invention relates to a screen reproducing method of a VTR system, and more particularly, to a method capable of reproducing a low speed and a still picture in a VTR system using an ATF signal.

In order to reproduce a picture in a conventional VTR system and a camcorder (Camera-Recorder), deck characteristic uniformity and volume were required.

Therefore, the screen is reproduced as described above by adjusting the volume, but there is a problem that noise is generated on the screen out of the original adjustment state over time according to errors, fluctuations and characteristics of the volume value.

Accordingly, an object of the present invention is to provide a method for reproducing a still picture and a low speed picture using an ATF signal in a VTR system.

It is still another object of the present invention to provide a method of accurately reproducing still and low speed pictures by analyzing the ATF signal in the VTR system and stopping at the start of the screen when the still or low speed pictures are played.

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

FIG. 1 is a system configuration diagram for implementing the present invention. The microcomputer 10 generates first and second selection signals SE LI and SEL2, receives and analyzes an ATF error signal, and generates a capstan driving signal. An ATF processing unit 20 for inputting the first and second selection signals SEI and SEL2 to reproduce an ATF signal from the head 30 to generate an ATF error signal, and capstan driving from the microcomputer 10; The capstan driver 40 is configured to control the driving of the capstan motor 50 by a control signal.

FIG. 2 is an operational waveform diagram of each part of FIG. 1, (2A) is a waveform diagram of a switching pulse (HS W) of the head 30, and (2B) is a waveform of a drive control signal CMD of the capstan driver 40. FIG. 2C is a waveform diagram of the first selection signal SEI, 2D is a waveform diagram of the second selection signal SEL2, and 2E is a waveform diagram of the reference pilot signal REF PILOT. (2F) is a waveform diagram of an ATF error (Auto Track Finding Error: ATFE).

3 is a flowchart of still play and slow play according to the present invention.

Based on the above-described configuration, the present invention will be described in detail with reference to FIGS.

In general, an ATF system (Auto Track Finding System) means that a head having the same azimuthangle when the head tracks a track in a VTR or a digital audio tape recorder system (DAT) using 8 mm tape is used. It is a system that controls the tracks of mus, and automatically controls the tracks of the tape by allowing the envelope signal to be output at maximum. Therefore, in the ATF system as described above, when the stop mode key is input while the track is correctly matched in the regeneration mode, the rising edge of the switching pulse signal HSP of the head 30 such as 2A is rising. After 2 ms from the edge), when the capstan drive signal (CMD) is shifted to the “low” state as shown in (2B), the capstan motor (50) is stopped, which causes the tape to stop running in the center of field 1. Because it is stopped, it becomes a field stop state, and in the case of a VTR using a special head, a clear still picture is obtained.

When the still picture playback mode is performed as described above, the microcomputer 19 outputs the first and second selection signals SEI and SEL2 such as (2C) and (2B) to the ATF processing unit 20. And a reference pilot signal such as 2E is determined according to the conversion of the second selection signals SEI and SEL2. The ATF processing unit 20 generates an ATF error signal (ATFE) signal such as (2F) by the difference between the reference pilot signal such as (2E) and the ATF pilot signal reproduced through the head 30 on the tape. And output to the microcomputer 10. At this time, the microcomputer 10 samples the first and second ATF error signals ATFE such as (2F) at the Y and Z time after the first field delay is stable, and the sampling time of the Y and Z time. The stopping time of the capstan motor 50 is determined by comparing the magnitudes of the first and second sampling signals obtained from. That is, the stop point of the capstan motor 50 is determined by calculating the first and second sampling values of the Y and Z time points, the characteristics of the deck, the running speed of the tape, the coefficient of friction of the pinch-roller, and slip ( When the capstan motor 50 does not stop at the position due to a slip) coefficient or the like, the sampling values of the Y and Z time points are incorrect, and the capstan motor 50 takes into account the information as much as the error amount at the next stop time. It will change the stop time of. Therefore, since the capstan motor 50 is stopped at the correct position during the playback of the still image, the head 30 can reproduce a still image of high quality.

The operation process will be described in detail with reference to the flowchart of FIG. 3.

First, in step 301, the microcomputer 301 checks the state of the system mode. At this time, if the playback mode is determined in step 301, the type of the playback mode is analyzed. If a still key is input, the playback mode is determined in step 302 and the stop mode is played in step 303. Set the variable α to stop to zero. (α = 0 ms) and then proceed to step 304 to stop the driving of the capstan motor 50 in the flow as shown in FIG.

That is, the microcomputer 10 waits until the head switching pulse HSP such as 2A generated from the head 30 reaches the rising edge in step 351, and the head switching pulse HSP rises. In the step 352 after edge detection, the tape is driven to the center of one field, and delayed by tms as in (2B) (t = x + α), and then the capstan driving signal CMD in the low state is generated. After waiting for one field period in step 353, in step 354, an ATF error signal ATFE, such as 1F, received from the ATF processing unit 20 at Y and Z points is sampled. In this case, the ATF processing unit 20 includes the reference pilot signal and the head determined by the first and second selection signals SEL1 and SEL2 such as (2C) and (2D) output from the microcomputer 10 as described above. An ATF error signal ATFE such as (2F) is detected by the difference of the ATF pilot signal reproduced through 30, and the relationship between the first and second selection signals SEI and SEL2 and the reference pilot signal Is shown in Table 1 below.

TABLE 1

One microcomputer 10 receives the ATF error signal generated by the ATF processing unit 20 as described above, takes a first sampling value at a point in time Y after the f2 signal is generated in the f4 period, and the next f2 signal is The second sampling value is taken at time Z, which is a predetermined time before it is generated.

Therefore, after taking the sampling values of the Y and Z time point through the step (354) in the same manner as above, the stop time of the capstan motor 50 is determined through the steps (355) to (358). In this case, when the capstan motor 50 stops at the theoretically correct position in the stop regeneration mode, the sampling values at the Y and Z time points have the same size. Based on the above principle, YZ (YZ = 0) is the sampling value of Y and Z. In step 355, when the operation result is displayed, the still image becomes “0” in step 357, and thus t = xms initially set. After the time, the capstan motor 50 is stopped and the transition to the stop regeneration mode is made.

However, as described above, when the capstan motor 50 does not stop in position due to deck characteristics, tape travel speed, pinch roller friction coefficient, slip coefficient, etc., the sampling values at the Y and Z time points are different from each other. The stop time of the capstan motor 50 is changed in consideration of the value at the next stop. That is, if Y > Z, the phase is fast, and in step 356, the capstan motor 50 is stopped by delaying the phase by? Ms with t = xms as the initial set time t = (x + α) ms.

In the case of Y <Z, since the phase is late, in step 358, the initial setting time t = xms is set to t = (x-α) ms, which causes the capstan motor (50) from the switching edge of the head 30. Shorten the stop time. Therefore, the capstan motor 50 is automatically stopped at the correct position by observing the picked-up magnitude of the ATF error signal ATFE, so that a fine still image can be reproduced.

Second, the operation of the low speed screen playback is described.

If a slow key is input, the microcomputer 10 is determined to be a slow play back mode in step 305, in which a still picture playback and a normal playback are alternately performed.

Therefore, if it is determined that the low speed regeneration mode is reached, in steps 306 and 307, the period f2 and f4 of the reference pilot signal such as 2E is reached until the head switching pulse MSP reaches the rising edge in step 308. After waiting, the capstan motor 50 is stopped at the correct position in the flow as shown in FIG. 3 (b) in step 309, and the video signal of the corresponding field is reproduced in step 301. At this time, the video signal is reproduced in the designated low speed mode by reproducing twice in the 2 low speed mode and 3 times in the 2 low speed mode according to the type of the low speed reproducing mode. Subsequently, in step 311, the capstan motor 50 is stopped by stopping to the position of the next field in the same flow as in FIG. 3B. Then, the process returns to step 305 to perform the slow play mode in the next field. do.

As described above, by sampling the ATR error signal in the VTR of the ATF system, the track stop position can be automatically detected by the difference of the sampling signals, and the capstan motor can be stopped at the correct position. There is an advantage in that it is possible to reproduce a still image and a low speed image regardless of the error.

Claims (2)

In the still picture reproducing method of the VT system using the tape of the ATF method, the process of waiting for the generation of the head switching pulse upon receiving the stop mode signal, and driving the capstan motor for a set time when the head switching pulse is generated The ATF error signal is first sampled after a predetermined time has elapsed at the start of the reference pilot section generating the ATF error signal after waiting for the one field period and stopping the one field period. A second sampling of the ATF error signal before time; analyzing the first sampling value and the second sampling value; and when the first sampling value and the second sampling value are the same during the analysis, the capstan Reproducing the still image at the current position without driving the motor, and when the first sampling value is larger than the second sampling value in the analysis process Calculating a difference time based on a fling value, adding the calculated difference time to the set time, driving the capstan motor, and then stopping and reproducing a still image; When the difference is less than the second sampling value, the difference time is calculated by the two sampling values, and the calculated difference time is subtracted from the set time to drive the capstan motor and then stop to play the still picture. How to play back still images. A method of reproducing a slow playback screen of a VT system using an ATF tape, the method comprising: waiting for a reference pilot signal period for detecting an ATF error signal upon receiving a slow playback mode signal; Waiting for the occurrence of a reference pilot signal period temporary head switching pulse for detecting the; and driving the capstan motor for a set time when the head switching pulse occurs; First curing the ATF error signal after curing for a predetermined time at the start of the reference pilot section generating the ATF error signal after waiting for a period, and secondly sampling the ATF error signal before the predetermined time at the end; Analyzing a first sampling value and a second sampling value; and in the analyzing step, the first sampling value and the second sampling value Reproducing a still image at the current position without driving the capstan motor when the fling values are the same; and calculating the difference time between the two sampling values when the first sampling value is larger than the second sampling value in the analysis step. Adding the calculated difference time to the set time to drive the capstan motor and stopping it; and calculating the difference time by two sampling values when the first sampling value is less than the second sampling value in the analysis step. And subtracting the calculated difference time from the set time to drive the capstan motor and then stopping it, and performing a normal play mode for a set field period after performing the still picture play process. And a process of returning to a still picture playback process after the mode process and the play mode process are performed. How to play egg slow screen.

Images