KR920004440Y1 - Skew preventing system of ntsc & pal combined use vtr - Google Patents

Abstract

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Description

Double azimuth skew prevention system for both NTSC and PAL of VTR

1 is a block diagram of one embodiment of a DA-6 video head configuration according to the present invention.

2 is a block diagram of another embodiment of the DA-6 video head configuration of FIG.

3 is a detailed circuit diagram of a skew prevention system according to the present invention.

4 is a videohead and preamplifier selection table according to each mode of FIG.

* Explanation of symbols for main parts of the drawings

10: video red section 20: preamp section

30: preamp output switching unit 40: signal type switching unit

50: video signal output switching unit 80: SP CH1 video head

82: SP CH2 video head 84: NTSC EP CH1 video head

86: NTSC EP CH2 video head 88: PAL LP CH2 video head

90: PAL LP CH1 video head 100: video signal output terminal

200: video head drum

The present invention relates to a skew prevention system of a video tape recorder (VTR), and in particular, a double azimyth (DA) system using a national television system committee (NTTR) method and a phase alternation by line (PAL) method of a VTR. The present invention relates to a DA-6 video head system which prevents skewing when a multi-function of SP (Standard Play) mode is performed in a video head system.

Currently, there are NTSC system and PAL system among color television systems, and the horizontal scanning frequency is different as one of the differences between the PAL system color television signal and the NTSC system color television signal. That is, the horizontal scanning frequency of the color television signal of the NTSC system is 15734.265HZ, and the horizontal scanning frequency of the PAL system color television signal is 15625HZ.

Therefore, since the one horizontal scanning period of the NTSC system and the PAL system is different, the mechanical one horizontal scanning period of the VTR for recording or reproducing the signals of the NTSC system and the PAL system is also different.

Therefore, if the multi-function of PAL SP mode is performed with the DA-4 video head for NTSC, the video head is different from the mechanical one horizontal scanning period of the NTSC DA-4 video head and the mechanical one horizontal scanning period of the PAL method. When switching, skew occurs when the horizontal synchronization signal is not matched, and the screen state deteriorates. In addition, the same skew occurs when the multifunction of NTSC SP mode is performed with the PAL DA-4 video head.

Therefore, in order to prevent the occurrence of skew, in the conventional VTR, a circuit for compensating different horizontal scanning periods of the NTSC method and the PAL method using a CCD (Charge Coupled Device) or a glass delay line is adopted. However, when the skew is compensated for using the CCD or the glass delay line, there is a problem that the image quality is degraded due to the reduction of the fidelity of the video signal. In addition, the skew detection circuit malfunctions and skew is not compensated, and the phase of the color signal is shifted so that a black and white screen is displayed.

Accordingly, an object of the present invention is to provide a skew prevention system for reproducing a stable screen by preventing the occurrence of skew during the multi-function execution of the SP mode in the NTSC method and the PAL double double hedge method of the VTR.

The present invention for achieving the above object is a video head unit arranged on the video head drum (NTSC type mechanical horizontal scanning period and PAL type mechanical horizontal scanning period, respectively) and the video head portion, A pre-amp unit for inputting and amplifying each video signal reproduced by the unit; a servo circuit unit for outputting a video head switching signal, a signal type switching signal, and a video signal output switching signal; A preamplifier output switching unit for inputting a video signal of each of the first or second channel video heads outputted from the video signal and switching the video signal by the video head switching signal output from the servo circuit unit; Video signal output from the NTSC EP (Extnded Play) mode video head or PAL LP (Long Play) mode video head A signal type switching unit for inputting a video signal output and switching the signal based on a signal control signal output from the fraudulent servo circuit unit, and outputting the video signal output from the preamplifier output switching unit and the video outputting from the signal mode switching unit. A video signal output for outputting a video signal of an SP mode video head, a video signal of an NTSC EP mode video head, or a video signal of a PAL LP mode video head by a video signal output switching signal inputted from the servo circuit section by inputting a signal. It is characterized by consisting of a switching unit.

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

1 is a block diagram of an embodiment of a configuration of a DA-6 video head according to the present invention, wherein an SP mode first channel (hereinafter referred to as SP CH1) video disposed at an arbitrary position on the circumference of the video head drum 200. The SP mode second channel (hereinafter referred to as SP SH2) video head 82 disposed at an interval of 180 ° from the head 80 and the SP CH1 video head 80, and from the SP CH2 video head 82; The NTSC EP mode first channel (hereinafter referred to as NTSC EP CH1) video head 84 and the SP CH1 video head disposed to be spaced apart by an integer multiple interval ("A") of the mechanically one horizontal scanning period of the NTSC system clockwise. 80) an NTSC EP mode second channel (hereinafter referred to as NTSC EP CH2) video head 86, which is arranged counterclockwise from the NTSC system by an integral multiple interval ("A") of the mechanically one horizontal scanning period. Integer interval "B" of the mechanical horizontal scanning period of the PAL method clockwise with the SP CH2 video head 82. PAL LP mode first channel (hereinafter referred to as PAL LP CH1) video head 88 and SP SP1 video head 80 arranged at a distance from each other by an integral multiple of the PAL-type mechanical horizontal scanning period (clockwise). And a PAL LP mode second channel (hereinafter referred to as PAL LP CH2) video head 90 arranged by " B "

FIG. 2 is a schematic diagram of another embodiment of the DA-6 video head configuration of FIG. 1, in which the NTSC EP CH1, 2 video heads 84-86 and PAL LP CH1, 2 video heads 88-90 are shown in FIG. The positions of are changed to suit the mechanical horizontal scanning period of NTSC and PAL respectively.

3 is a detailed circuit diagram of a skew prevention system according to the present invention, and the video is taken in consideration of each horizontal scanning period according to the SP CH1, two video heads 80-82 for NTSC and PAL methods, and NTSC or PAL methods. DA-6 video consisting of NTSC EP CH1, 2 video heads (84-86) for NTSC type EP mode, and PAL LP CH1, 2 video heads (88-90) for PAL mode LP mode, arranged on the head drum. The video head unit 10 which reproduces the video signal recorded on the video tape with the head, and the reproduction in each video head 80-90 of the video head unit 10 inputs the respective video signals. The preamp unit 20 composed of the first, second, third, fourth, fifth, and sixth preamps 21-26 to be recorded, the video head switching signal P1, and the signal type switching signal P2. ) And a servo circuit unit 30 for outputting a video signal output switching signal P3, and a first mode of each mode output to the preamplifier unit 20. Alternatively, a preamplifier output switching unit which inputs a video signal of a second channel video head and switches to a switch SW1-SW3 interlocked by a video head switching signal P1 input from the servo circuit unit 30. And a video signal of the NTSC EP CH1, 2 video heads 84-86 or the PAL LP CH1, 2 video heads 88-90 outputted from the video head output switching unit 40. A signal type switching unit 50 which switches to switch SW4 by a signal type switching unit P2 inputted from the servo circuit unit 30 and outputs a video signal of a currently selected type, and the preamplifier output The video signal of the SP CH1, 2 video heads 80-82 output from the switching unit 40 and the video of the NTSC EP CH1, 2 video heads 84-86 output from the signaling method switching unit 50. The servo circuit unit 30 by inputting a signal or a video signal of PAL LP CH1, 2 (88-90); The video signal of the SP CH1, 2 video heads 80-82 or the video signal of the NTSC EP CH1, 2 video heads 84-86 is switched to the switch SW5 by the video signal output switching signal P3 inputted from the Or a video signal output switching unit 60 for outputting video signals of the PAL LP CH1 and the two video heads 88-90.

On the other hand, of the signals output from the servo circuit unit 30 of FIG. 3, the video head switching signal P1 is arranged on the video head drum in consideration of the horizontal scanning period according to the NTSC method or the PAL method. The first and second channel video signals of the respective modes output from the preamplifier 20 according to the position of 80-90 are input to the preamplifier output switching unit 40.

Signal switching signal (P2) is NTSC EP CH1, 2 video head (84-86) or PAL LP CH1, 2 video head (88-86) suitable for the currently selected method of the video signal output to the preamplifier output switching unit 40 90 is a signal input to the signal type switching unit 50 so as to select the video preference.

The video signal output switching signal P3 outputs the video signals of the SP CH1 and 2 video heads 80-82 among the video signals output from the preamplifier output switching unit 40 from the signal switching unit 50. The video signal output switching unit 60, which inputs the video signal of the NTSC EP CH1, 2 video heads 84-86 or the video signal of the PAL LP CH1, 2 video heads 88-90, sets the NTSC SP mode or the VTR. The video signal of the SP CH1, 2 video heads 80-82 is output in the PAL mode SP mode, and the video of the NTSC EP CH1, 2 video heads 84-86 is output in the NTSC mode EP mode. It outputs a signal and outputs PAL LP CH1, 2 video heads (88-90) video signal during PAL mode LP mode playback, and SP CH1, 2 video heads (80-90) when performing multifunction in NTSC mode SP mode. 82) and the video signal having the larger gain among the video signals of the NTSC SP CH1, 2 video heads 84-86. In the PAL SP mode, when the multifunction is performed, the video signal of the gain of the PAL LP CH1 or 2 video heads 88-90 of the video signals of the SP CH1 and 2 video heads 80-82 is outputted. A signal for switching the switch SW5 of the video signal output unit 60.

Meanwhile, a, b, c, and d represent corresponding lines of FIG. 3.

FIG. 4 shows respective video heads and preamplifiers selected by the video head switching signal P1, the signal type switching signal P2, and the video signal output switching signal P3 according to each mode of FIG.

Hereinafter, an operation example of FIG. 3 according to the present invention will be described in detail with reference to FIG. 4.

The NTSC method recorded on the video tape by the SP CH1 video head 80 or the SP CH2 video head 82 of the video head unit 10 during the playback operation in the NTC SP mode or PAL LP mode in the VTR as in FIG. 4A or The PAL video signal is reproduced and input to the first preamplifier 21 and the second preamplifier 22, respectively, and the first and second preamplifiers 21-22 are the NTSC or PAL video signals. Input to amplify and output. Therefore, the preamplifier output switching unit 40 inputs an NTSC or PAL video signal outputted to the first and second preamplifiers 21-22 and outputs the head switching signal outputted from the servo circuit unit 30. P1) switches the NTSC or PAL video signal reproduced by the SP CH1 video head 80 or the SP CH2 video head 82 to the switch SW1 for output. In addition, since the switch SW5 is connected to the line a by the video signal output switching signal P3 output from the servo circuit unit 30, the playback is performed by the SP CH1 head 80 or the SP CH2 video head 82. The NTSC or PAL video signal is output to the video signal output terminal 100.

On the other hand, during the playback operation in the NTSC EP mode in the VTR as shown in FIG. 4C, the NTSC system recorded on the video tape by the NTSC EP CH1 video head 84 or the NTSC EP CH2 video head 86 of the video head unit 10 is recorded. The video signal is reproduced and input to the third preamplifier 23 and the fourth preamplifier 24, respectively, and the NTSC video signals output from the third and fourth preamplifiers 23 to 24 are inputted to the The video signal of the NTSC system reproduced by the NTSC EP CH1 video head 84 or the NTSC EP CH2 video head 86 by the video head switching signal P1 output from the servo circuit unit 30 is switched (SW2). The output is converted to). In addition, since the NTSC type video signal is being processed by the signal type switching signal P2 output from the servo circuit unit 30, the switch SW4 is connected to the line b so that the NTSC type video signal is connected to the line d. Is output. Since the switch SW3 is connected to the line d by the video signal output switching signal P3 output from the servo circuit unit 30, the NTSC EP CH1 video head 84 or the NTSC EP CH2 head 86 is connected to the line d. The NTSC video signal reproduced by this is output to the video signal output terminal 100.

In addition, in the PAL LP mode playback operation in the VTR as shown in FIG. 4D, the PAL method recorded on the videotape by the PAL LP CH1 video head 88 or the PAL LP CH2 video head 88 of the video head unit 10 is used. The video signal is reproduced and input to the fifth preamp 25 and the sixth preamp 26, respectively, and the fifth and sixth preamps 25-26 input and amplify the video signal of the PAL method. Output Therefore, the preamplifier output switching unit 40 inputs a PAL video signal output from the fifth and sixth preamps 25-26 to the PAL LP CH1 video head 88 or the PAL LP CH2 video head. The PAL video signal reproduced by 90 is switched to the switch SW3 by the video head switching signal P1 output from the servo circuit section 30 and output.

Also, since the PAL system video signal is being processed by the signal system switching signal P2 output from the servo circuit unit 30, the switch SW1 is connected to the line c so that the PAL system video signal is connected to the line d. Is output.

Since the switch SW5 is connected to the line d by the video signal output switching signal P3 output from the servo circuit unit 30, the PAL LP CH1 head 88 or the PAL LP CH2 head 90 is connected. The reproduced PAL video signal is output to the video signal output terminal 100.

On the other hand, when performing multifunction in the NTSC SP mode in the VTR as shown in FIG. 4E, the video signal reproduced by the SP CH1 video head 80 or the SP CH2 video head 82 of the video head unit 10 is NTSC SP of FIG. The video signal reproduced by the NTSC EP CH1 video head 84 or the NTSC EP CH2 video head 86 by the same operation as in the playback operation in the mode is reproduced in the NTSC EP mode in FIG. 3C. The operation is the same as that on the line d. Therefore, the video signal output switching unit 60 inputs the video signal output to the line a and the video signal output to the line d and outputs the line signal by the video signal output signal P3 output from the servo circuit unit 30. The switch SW5 is connected to a line having a larger gain of the video signal among the lines d, and the video signal reproduced by the SP CH 1 and 2 video heads 80-82 or the NTSC EP CH 1 and 2 video heads ( 84-86) to the video signal output terminal 100 reproduced.

On the other hand, when the multifunction is performed in the PAL SP mode in the VTR as shown in FIG. 4f, the video signal reproduced by the SP CH1 videohead 80 or the SP CH2 videohead 82 of the videohead unit 10 is the PAL SP of FIG. 3b. The video signal reproduced by the PAL LP CH1 video head 88 or the PAL LP CH2 video head 90 by the PAL LP mode shown in FIG. The operation is the same as that on the line d. Therefore, the video signal output switching unit 60 inputs the video signal output to the line a and the video signal output to the line d and outputs the line by the video signal output signal P3 output from the servo circuit unit 30. A switch SW5 is connected to a line having a larger gain of a video signal among a and the line b so that the video signal reproduced by the SP CH 1 and 2 video heads 80-82 or the PAL LP CH 1 and 2 video heads. The video signal reproduced by (88-90) is output to the video signal output terminal (100).

As described above, the present invention skews by configuring the DA-6 head for NTSC type mechanical horizontal scanning period and PAL type mechanical horizontal scanning period on the video head drum in the NTSC type and PAL type VTR. Skew prevention system to prevent the occurrence of fidelity of the video signal can be prevented to reproduce a clear and clear multi-function screen.

Claims (2)

In the double edge mush type skew prevention system for both NTSC and PAL of VTR, the horizontal scanning period can be set according to the SP CH1 and 2 video heads (80-82) and NTSC or PAL for NTSC and PAL. DA consisting of NTSC EP CH1 and 2 video heads 84-86 for NTSC mode EP mode and PAL LP CH1 and 2 video heads 88-90 for PAL mode LP mode disposed on the video head drum. A video head unit 10 for reproducing a video signal recorded on a videotape with a -6 video head, and for each video signal reproduced at each video head 80-90 of the video head unit 10, A preamplifier 20 comprising a first, second, third, fourth, fifth, and sixth preamps 21-26 to amplify, a video head switching signal, a signal type switching signal, and a video signal output switching Servo circuit section 30 for outputting a signal, and each mode output from the preamplifier section 20 A preamplifier output switching unit for inputting a video signal of a first or second channel video head and switching to a switch SW1-SW3 interlocked by a video head switching signal input from the servo circuit unit 30; 40) and a video signal of NTSC EP CH1, 2 video heads 84-86 or PAL LP CH1, 2 video heads 88-90, which are output from the video head output switching unit 40, are inputted. A signal type switching unit 50 for switching the switch SW4 by a signal type switching signal inputted to the servo circuit unit 30 to output a video signal of a currently selected type, and the preamplifier output switching unit ( 40) video signal of SP CH1, 2 video heads 80-82 and NTSC EP CH1, 2 video heads 84-86 output from the signal switching unit 50 or PAL. The servo circuit unit 30 receives LP CH1, 2 (88-90) video signals. Switched to switch SW5 by the video signal output switching signal input from the SP CH1, the video signal of the two video heads 80-82, or the video signal of the NTSC EP CH1, the two video heads 84-86, or the PAL LP. A double azimuth type skew prevention system for both NTSC and PAL of the VTR, comprising a video signal output switching unit 60 for outputting video signals of CH1 and 2 video heads 88-90. 2. The DA-6 video head is disposed at 180 [deg.] Intervals with the SP CH1 video head 80 and the SP CH1 video head 80 disposed at their circumferential positions of the video head drum 200. The SP CH2 video head 82, and the NTSC EP CH1 video head 84 disposed apart from the SP CH2 video head 82 by an integer multiple interval (" A ") of the NTSC mechanically 1 horizontal scanning period; The NTSC EP CH2 video head 86 disposed at an interval of 180 ° with the NTSC EP CH1 video head 84, and the integer multiple intervals of the mechanical 1 horizontal scanning period of the PAL method from the SP CH2 video head 82 (" PAL LP CH1 videohead 88 and PAL LP CH1 videohead 88 disposed in the opposite direction to the NTSC EP CH1 videohead 84 and PAL LP CH1 videohead 88 spaced 180 ° apart Double azimuth system skew prevention system for NTSC method and PAL method of VTR, characterized by consisting of 90 .