KR900006780B1 - Double scanning circuit - Google Patents

Abstract

The circuit for compensating the image contour of vertical direction in NTSC television comprises delay circuits (1,2) delaying horizontal period as much as one (1H), mixers (M1-2) obtaining difference between bright signals of first and last lines, level rectifiers (3,4) filtering the difference signal having certain level, memories (5,6) reading the brightness data two times faster than writing, an analog switch (SW) providing control signal (CTB) formed by horizontal synch. signal for double scanning, a multiplier (7) adjusting the output peaking level of the analog switch, and a mixer (M3) providing the compensated contour signal.

Description

Vertical peaking circuit during double scan scanning

1 is a circuit diagram of the present invention.

2 is a scanning state diagram during a double scan of the present invention.

3 is a state diagram showing the period of the vertical synchronization signal during normal and double scan.

4 is a control signal state diagram represented by FIG.

* Explanation of symbols for main parts of the drawings

M ₁ -M ₃ : Mixer SW: Analog Switch

1,2: 1H delay unit 3,4: Level detector

5,6: 1H memory 7: Multiplier

I ₁ : Inverter

The present invention provides a double scan method in which a high-resolution screen can be obtained by doubling the image horizontal scanning player in one field by scanning two consecutive images of the same line during one horizontal period (1H). In a TV, it relates to a vertical peaking circuit during a double scan scan in which the luminance signal difference in the vertical direction is made larger so as to perform contour correction in the vertical direction.

The current TV signal is transmitted at 262.5 line / field in the NTSC mode, so the image is displayed in a very rough state, and the signal is transmitted at 262.5 line / field for viewing and converted into a signal of 525 line / field to reproduce the image. By developing a double scan scanning TV, the resolution is increased during double scan scanning, so that a clear image can be obtained. However, when a luminance signal difference in the vertical direction occurs, the double scanned TV signal cannot compensate for this vertically. The screen felt clumped toward the camera.

SUMMARY OF THE INVENTION In view of the above, the present invention provides a double scan scanning type TV that doubles the horizontal image scanning player in a field, and reads the difference between the front line and the back line of the displayed line and displays the luminance in the vertical direction. If a signal difference occurs, it is made larger to correct the vertical outline, thereby preventing the screen from crushing toward the vertical line during the double scan scan.

That is, in the double-scanned screen, the nth line adds the difference signal with the n-1th line and the n'th line subtracts the difference signal with the n + 1th line to achieve vertical peaking. will be.

This will be described in detail with reference to the accompanying drawings. 1 is a circuit diagram of the present invention, in which a digital scan of a digitalized luminance signal is performed in a double scan scanning type TV which doubles an image horizontal scanning player in a field by scanning the same line image twice in succession during one horizontal period. 1H delay unit (1) (2) which obtains n-1, n, n + 1th line signals by delaying to (1H), and luminance signal delayed through the 1H delay unit (1) (2) by mixing 1H Mixer M ₁ (M ₂ ) which obtains the difference between the front line luminance signal and the back line luminance signal centered on the delayed luminance signal, and a value greater than or equal to a certain magnitude from the value obtained from the mixer M ₁ (M ₂ ). The level detector (3) (4) which passes only the difference signal and the signal passed by the level detector (3) (4) are driven back together with the 1H delayed luminance signal and are written at the time of read. 1H memory (5) (6) read successively twice at twice the speed of An analog switch (SW) for switching the signal to a control signal (CTB) made by a double scan horizontal synchronization signal locked to a horizontal synchronization signal, and a multiplier for adjusting the peaking degree of the signal passing through the analog switch (SW) ( 7) and a mixer M ₃ for mixing the output of the multiplier 7 and the read signal of the 1H memory 5 and 6 to output the contour corrected signal in the vertical direction.

The present invention configured as described above makes the contour correction in the vertical direction larger when the luminance signal difference occurs in the vertical direction during the double scan, so that the signal as shown in FIG. 2 will be described as an example.

The signal displayed on the left side of FIG. 2 is a signal displayed on a TV of a general scanning method scanning at 262.5 line / field, and when it is displayed as a black, white, white, white, or black signal, if it is double scan based on the circuit of the present invention, By displaying such as' white ', white', white ', white', and 'white', the secondary becomes larger when the luminance signal difference in the vertical direction is generated. That is, in the double-scanned screen, the nth line adds the difference signal with the n-1th line and the n'th line subtracts the difference signal with the n + 1th line, as shown in the right side of FIG. The luminance signal difference is increased so that vertical peaking can be achieved.

This invention will be described in detail.

가 된다.First, in FIG. 3, the normal scanned screen scanned at 262.5 line / fiel d and the double scanned screen scanned at 525 line / field are shown. In this case, the horizontal period of the normal scanned screen is 1H, but the horizontal screen of the double scanned screen is 1H. The cycle is

Becomes

가 된다.The reason is that the horizontal period of the double-scanned screen is

Becomes

Therefore, if only the horizontal synchronizing signal is taken from the screen of FIG. 3, it can be obtained as shown in FIG. 4. If the output is changed at the falling edge of the horizontal synchronizing signal, the control signal (CTA) as shown in FIG. (CTB) can be obtained.

That is, if the horizontal synchronization signal as shown in FIG. 4 is applied to an input such as flip-flop and the output is inverted for each falling edge, the control signal CTA (CTB) as shown in FIG. 4 can be obtained. do.

에 인가되어 리드(Read), 라이트(Write)를 콘트롤 해주는 신호로써 n번째 라인이 1H메모리(5)에 리드되고 있으면 2배의 속도로 1H메모리(6)에서 n-1번째 라인을 2번 읽어내게 된다.This control signal CTA is a read / write terminal of the 1H memory 5, 6

It is a signal that is applied to read and write to control the nth line and reads n-1th line from 1H memory 6 twice at twice the speed if the nth line is being read to 1H memory 5. To me.

The control signal CTB selects the difference signal indicated by n- (n-1) when the n-th line is read by selecting the drive of the analog switch SW, and (n + 1) when the n-th line is read. Causes the difference signal of -n to be selected.

The present invention of this operation will be described in detail with reference to FIG.

First, the quantized digital luminance signals are delayed by 1H through the 1H delay units 1 and 2 to obtain the signals of the n-1, n, and n + 1th lines, and the signals are mixed with the mixer M ₁ (M ₂ ). ) To obtain the difference signal (A) (B).

That is, the mixer M ₁ subtracts the n-th line signal passing through the 1H delay unit ₁ from the input digital luminance signal (n + 1th line signal) and subtracts the difference signal A of (n + 1) -n. ), And the mixer (M ₂ ) subtracts the n-1th line signal passing through the 1H delay unit (2) from the nth line signal obtained from the 1H delay unit (1) to obtain the difference of n- (n-1). You get a signal (B).

In this way, the line signals A and B are combined by combining the line signals of the 1H delay units 1 and 2 with delayed luminance signals in the mixers M ₁ and M ₂ to obtain the difference signals A and B. B) is input to the 1H memory 5 and 6 through the level detectors 3 and 4 which pass only the difference signal of a certain magnitude or more so as to avoid peaking in the small difference signal. (5) and (6) read and write operations are controlled by the control signal CTA shown in FIG. 4. When the nth line is read into the 1H memory 5, the 1H memory ( In line 6), the n-1th line is read twice.

When the analog switch SW is selected by the control signal CTB as shown in FIG. 4, when the nth line is read, the difference signal represented by n- (n-1) is selected and the n'th line is read. The difference signal represented by (n + 1) -n is selected, and the difference signal selected by the analog switch SW is applied to the multiplier 7 to determine the peaking degree and to be applied to the mixer M ₃ . The n-line scanned by the double scan is added with a difference signal multiplied by n- (n-1) by k of the multiplier 7, and scanned by n + k {n- (n-1)}. A value multiplied by k multiplied by n + 1) -n is added to be scanned as nk {n- (n + 1)} = n + k {(n + 1-n)}.

Where k is an integer less than or equal to 1 and controls the amount of peaking.

That is, in order to achieve vertical peaking during double scan, the nth line adds the difference signal with the n-1th line and the n'th line has the difference signal with the (n + 1) th line in the double scanned screen. The nth line is displayed as n + k {n- (n-1)} and the n'th line is nk {-(n + 1)} = n + k {( n + 1) -n}.

Therefore, in the double-scanned screen, when the luminance signal difference in the vertical direction occurs, it is possible to eliminate the defect that the vertical resolution is reduced by making the vertical contour correction by making it larger.

As described above, the present invention obtains the difference between the signals of the front and rear lines displayed during the double scan, and vertically peaks to an appropriate value to prevent the loss of the vertical screen and at the same time high resolution. It can be provided.

Claims (1)

1H delay unit for delaying the digitized luminance signal by one horizontal period (1H) in a double scan TV that doubles the image horizontal scanning player in a field by scanning two consecutive images of the same line in one horizontal period. (l) (2) and a mixer (M ₁ ) (M) which obtains the difference between the front line luminance signal and the back line luminance signal centered on the horizontal signal delayed luminance signal through the 1H delay unit (1) (2). in _2), the mixer (M ₁₎ (M _2), the level detector (3) (4) and said level detector (3) (4) for primary signs,. pass certain size must be at least a difference signal obtained by the 1H memory (5) (6) and 1H memory (5) (6), which are driven inversely with one horizontal period delayed luminance signal and are read two times consecutively at a rate of twice the read-time. The control signal (C) created by the horizontal sync signal for double scanning, in which the signal read from TB), the multiplier 7 for adjusting the peaking degree of the signal passing through the analog switch SW, the output of the multiplier 7 and the 1H memory 5 (6). Vertical peaking circuit in a double scan scan composed of a mixer (M ₃ ) for mixing the read signal of the () to output a vertically corrected signal in the vertical direction.

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