JPH06205245A - Contour compensation processor by scanning line density modulation of picture - Google Patents

Abstract

PURPOSE:To execute an appropriate compensation by applying density modulation to a scanning line in a CRT display device. CONSTITUTION:A Y signal (luminance signal) is processed by 1H delay lines 1a 1b for second order derivative, adder circuits 2, 3 and a coefficient device 5 and a vertical contour compensation signal f' is obtained by an LPF 6 and a gain control circuit 7. The compensation signal is fed to a coil drive circuit 10, in which a density modulation coil 11 of a CRT display device is driven. Thus, the density modulation is applied to a scanning line at a vertical contour part of a picture in the CRT display device and the contour is compensated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CRT display device,
In particular, the present invention relates to an improved vertical contour compensating device for performing vertical contour compensation of an image luminance component signal.

[0002]

2. Description of the Related Art In a conventional CRT display device, a vertical contour compensating device for a display image is constructed as shown in FIG. In the figure, 1a and 1b are 1 for the second-order differentiation circuit.
H delay line, 2, 3 and 4 adders, 5 1/2 coefficient unit,
6 is a low pass filter (LPF), 7 is a gain control circuit,
Reference numeral 8 is a beam amplifier, and 9 is an electron gun of a CRT display device.

FIG. 8 shows an example of the signal waveform of each part of the apparatus of FIG. 7, where a is an input Y signal waveform (for example, a white window signal with respect to the peripheral gray), and b is 1H with respect to the input Y signal.
(1 horizontal scanning time) delay signal, c is 2H delay signal with respect to input Y signal, d is addition output signal of input Y signal and 2H delay signal, e is -1/2 signal of the signal d, and f is An addition output signal of the signal e and the 1H delayed signal b, and f ′ is the signal f
Is a vertical contour compensation signal extracted via the LPF 6 and the gain control circuit 7, and g is an output signal obtained by adding the 1H delay signal b to the signal f ′ and becomes a luminance signal including the vertical contour compensation signal.
The brightness signal is applied to the beam amplifier 8, and vertical contour compensation is performed by increasing or decreasing the beam current applied to the electron gun 9.

[0004]

In the above-described conventional contour compensation method, the level of the beam current is increased or decreased according to the magnitude of the contour compensation signal S in order to compensate the vertical contour portion.
So, for example, compensation in the white part of the contour would have to increase the beam current above the white level,
The beam spot diameter spreads in the high brightness area. Since the beam spot diameter affects the resolution, widening the beam spot diameter not only lowers the resolution but also prevents proper contour compensation at the contour portion. However, since the beam spot diameter is determined by the electron gun, a special electron gun is required to perform appropriate contour compensation by the conventional method, which is not practical. Further, when compensating a video signal with a gradual change in luminance, the amount of compensation is small and a sufficient effect cannot be obtained.

It is an object of the present invention to propose a device which enables appropriate contour compensation by changing the density of scanning lines without increasing the beam current.

[0006]

In order to achieve the above object, the first invention of the present application is to delay an image luminance component signal for a predetermined time based on a horizontal scanning time and output a delayed signal, and the above image. A synthesis processing means for synthesizing the luminance component signal and the delay signal, inverting the phase and outputting a synthesis processing signal multiplied by a predetermined number, and a contour compensation processing by an addition operation of the delay signal and the synthesis processing signal to perform a vertical contour. Vertical contour compensation processing means for obtaining a compensation component signal, and horizontal and vertical deflection magnetic fields are generated based on the horizontal and vertical deflection component signals generated from the image luminance component signal to perform horizontal and vertical scanning of the beam for image display. CRT display means and the CRT
Vertical density modulation means, which is provided at a position which gives only a vertical displacement of the beam of the display means, generates a vertical compensation magnetic field based on the vertical contour compensation component signal, and superimposes it on the vertical deflection magnetic field. And

The second invention of the present application synthesizes the image brightness component signal and the delay signal with delay means for delaying the image brightness component signal by a predetermined time based on the horizontal scanning time and outputting the delayed signal. A synthesizing processing means for inverting the phase and outputting a synthesized signal multiplied by a predetermined value, and a rising edge and a falling edge of the image luminance component signal based on a difference signal between the image luminance component signal and the delay signal and a predetermined reference signal. Luminance change detecting means for obtaining a detection signal corresponding to the detection result, a signal obtained by synthesizing the image luminance component signal and the delay signal based on the detection signal, and the synthesizing process. A signal and a signal for selecting and adding the signals, and a contour compensation process based on the added output of the synthesized signal and the synthesized signal in the signal selection and output means to perform vertical contour compensation. CR that by generating horizontal and vertical deflection magnetic field to the image display performs horizontal and vertical scanning of the beam on the basis of the vertical contour compensation processing means for obtaining a signal, the image luminance component signal horizontal and vertical deflection component signal generated from
A T display means and a vertical density modulation means which is provided at a position where only a vertical displacement of the beam of the CRT display means is provided, and which generates a vertical compensation magnetic field based on the vertical contour compensation component signal and superimposes it on the vertical deflection magnetic field. , Is provided.

[0008]

In the apparatus of the first aspect of the present invention, the image luminance component signal is combined with a signal obtained by delaying the signal based on the horizontal scanning time, further phase-inverted and processed so as to be multiplied by a predetermined value to form a combined processing signal. . This combined processing signal is added to the delay signal to obtain a vertical contour compensation component signal, and a vertical compensation magnetic field generated based on the signal is superimposed on the vertical deflection magnetic field to perform vertical density modulation of the scanning line. In the device of the second aspect of the present invention, rising and falling luminance changes of the image luminance component signal are detected, and a combined signal of the image luminance component signal and the delayed signal based on the detected signal and the combined processed signal. And are selected and added. Then, a vertical contour compensation component signal is obtained based on this addition output.

[0009]

Embodiments of the present invention shown in the drawings will be described below.
FIG. 1 shows an embodiment of a vertical contour compensating device according to the present invention. The same reference numerals as those in FIG. 7 represent the same or similar circuits. In this embodiment, a coil drive circuit 10 and a vertical density modulation coil 11 of a CRT are further provided. Is provided.

As described above, the vertical contour compensation signal f'generated by the second-order differential circuit using the two 1H delay lines is added to the coil drive circuit 10, current amplified, and given to the vertical density modulation coil 11. As a result, a density modulation magnetic field of the scanning line having a similar waveform is generated in the vertical contour portion. In the CRT display device provided with the above-mentioned coil, the beam is vertically scanned by the vertical deflection sawtooth magnetic field. Therefore, the vertical magnetic field received by the beam is the vertical deflection sawtooth magnetic field and the density modulation magnetic field (vertical contour compensation magnetic field), and the vertical deflection sawtooth magnetic field apparently having a contour compensation waveform acts on the beam. Vertical scanning line density modulation is performed.

In this case, the installation position of the coil 11 is such that the beam is displaced only in the vertical direction by the compensation magnetic field.
Set to the position of the electron gun. For example, if a horizontal displacement component is applied to the beam by the coil, proper compensation may not be performed on the CRT display surface or color misregistration may occur. Therefore, the actual coil installation position may be the deflection of the CRT neck portion. Immediately after the coil is desirable. The scanning line density modulation according to the present invention will be further described. In normal scanning, since the scanning lines are vertically scanned at uniform intervals by the vertical deflection sawtooth wave, for example, the luminance change when changing from the gray level to the white level is as shown in FIG.

However, in the present invention, when the density modulation is performed as described above, a compensation magnetic field is generated by the vertical density modulation coil 11 on the basis of the vertical contour compensation signal obtained by the second derivative of the Y signal, and this magnetic field is generated. The vertical deflection sawtooth magnetic field can be changed as shown in FIG. As a result, the spacing (density) of the scanning lines changes in the vertical contour portion. The luminance on the CRT display surface in the portion where the density of the scanning lines is sparse is reduced, and the luminance in the portion where the density is dense is improved. Also, since the density of the scanning lines is usually uniform, the density becomes dense on the line next to the scanning line where the density becomes sparse, and becomes sparse at the line next to the scanning line where the density becomes dense. Therefore, in the case of the Y signal changing from the gray level to the white level, the brightness change is as shown in FIG.
At this time, in the vertical contour portion, the difference between the gray level and the white level is increased and contour compensation is performed. In this embodiment, 2
Although the vertical contour compensation signal is obtained by the first derivative, the same compensation signal can be obtained by the first derivative configuration as shown in FIG.

FIG. 10 shows the difference in luminance change between the method of the present invention and the conventional method. As is clear from the figure, when the contour compensation is performed by the first-order differential, only the white level luminance increases in the conventional method. However, in the method of the present invention, the gray level luminance decreases and the white level luminance increases. Therefore, the brightness level difference of the contour portion is larger in the method of the present invention than in the conventional method.

11 (a) and 11 (b) are enlarged views of the contour portion 30 of the image by the normal scanning and the density modulation scanning of the present invention, respectively. As an example, this is a case where the peripheral portion is a gray level and a white level window pattern is displayed inside thereof, and the shaded portion of the contour portion 30 is a white level. Considering the contour part in the case of the density modulation scanning in comparison with the normal scanning, the part where the white level of the scanning lines l ₂ and l ₃ exists (the part where the luminance change occurs with respect to the previous scanning line, that is,
Positions P ₁ and P ₂ of the scanning lines in the vertical contour portion are displaced as shown in FIG. 11B due to the compensating magnetic field due to the contour compensation, resulting in non-uniformity (density) in the density distribution of the horizontal scanning lines. As a result, the contour enhancement described above is performed. Similarly, the density of the scanning line is also modulated at the trailing edge of the contour portion to enhance the contour.

Further, when the second-order differential waveform signal of the vertical contour is used when performing the vertical contour compensation by the above-mentioned density modulation, the contour rising and falling portions are shown in FIG. As shown, compensation asymmetry may occur. That is, in FIGS. 4A and 4B, in the contour compensation by the second derivative, one contour compensation is performed by two lines including the contour. Here, for example, considering the rising edge, the scanning line moves upward as shown by the arrow and moves downward in the next line. Then, on the falling edge, the scan line moves down as indicated by the arrow and moves up on the next line. Therefore,
As shown in FIG. 4 (a), the contour compensation of the above-described method may cause an asymmetric image at the rising edge and the falling edge to reproduce an unnatural image.

FIG. 5 (a) is further improved in that in the embodiment of FIG. 1 the asymmetry of the rising edge and the falling edge of the contour described above is further improved, and the contour of the image at the time of vertical contour compensation is unnatural. In another embodiment of the present invention for effectively performing vertical contour compensation without causing the above, the same reference numerals as those in FIG. 1 represent the same or similar circuits, 20 is a comparator, 21 is a 1H delay line, Reference numeral 22 is a TTL circuit, 23 is an AND gate, 24 is an analog switch, 25 is a coefficient multiplier, and 26, 27 and 28 are subtractors. FIG. 5B shows the signal waveform of each part.

In FIG. 5A, a second-order differential waveform signal a is obtained at point a. Further, in order to detect the edge polarity, the first-order differential waveform signal b is obtained at the point b, added to the comparator 20, and compared with a predetermined reference signal Er to detect the edge rise (or edge fall) of the edge, The level-converted detection signal b ₁ is obtained.
This signal b ₁ and the signal b ₁ are 1H by the 1H delay line 21.
(1 horizontal scanning time) The signal b ₂ which has been delayed and passed through the TTL circuit 22 and the gate pulse e for driving the polarity selecting analog switch 24 are applied to the AND gate 23.
To get When the switch 24 is driven by the pulse e, the signal a and the signal obtained by processing the signal a by the coefficient unit 25 are selected and added and output. From the added output signal f, it is possible to distinguish the rising edge and the falling edge of the contour as shown in FIGS. 6A and 6B, and obtain a compensation signal having a polarity suitable for the contour. As a result, as shown in FIG. 6A, the rising and falling portions of the luminance distribution are symmetrical.

12 and 13 are photographs of the signal waveform and the oscilloscope waveform showing the luminance distribution on the CRT screen, respectively, taken by the same camera and under the same photographing conditions, respectively, as shown in FIGS. As is apparent from these, according to the present invention, the asymmetry of the contour portion is eliminated.

[0019]

As described above, according to the vertical contour compensation device of the present invention, vertical contour compensation can be performed without increasing the beam current and expanding the beam spot diameter. Further, according to the present invention, the level difference of the contour portion can be made larger than that of the conventional method. Furthermore, in particular,
When the apparatus of the second invention is used, the asymmetry of the rising edge and the falling edge of the contour portion is not brought about, and the contour of the image at the time of vertical contour compensation becomes natural.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a luminance change during normal scanning on a CRT.

FIG. 3 is an explanatory diagram of a luminance change at the time of density modulation scanning in the device of the present invention.

FIG. 4 is an explanatory diagram when asymmetry of a compensation magnetic field occurs.

FIG. 5 (a) is a block diagram showing another embodiment of the present invention. (B) It is a waveform diagram for explaining the operation of the above embodiment.

6 is an explanatory diagram of a scanning line structure according to the embodiment of FIG.

FIG. 7 is a block diagram showing a conventional vertical contour compensation device.

8 is a signal waveform diagram of each part of the apparatus of FIG.

9 is a block diagram showing a modification of the embodiment of FIG.

FIG. 10 is an explanatory diagram showing a difference in luminance change between the method of the present invention and the conventional method.

FIG. 11 is an enlarged view of a contour portion of an image by normal scanning and scanning of the present invention.

FIG. 12 is a photograph of an oscilloscope waveform showing a conventional signal waveform and a luminance distribution on a CRT screen.

FIG. 13 is a photograph of an oscilloscope waveform showing the signal waveform of the method of the present invention and the luminance distribution on the CRT screen.

[Explanation of symbols]

 1a, 1b 1H delay line 2, 3, 4 adder 5 coefficient unit 6 LPF 7 gain control circuit 9 CRT display device 10 coil drive circuit 11 density modulation coil

Claims (2)

[Claims] 1. A delay means for delaying an image luminance component signal for a predetermined time based on a horizontal scanning time and outputting a delay signal, and a synthesis for synthesizing the image luminance component signal and the delay signal, inverting the phase and multiplying by a predetermined number. Synthesis processing means for outputting a processed signal; vertical contour compensation processing means for obtaining a vertical contour compensation component signal by performing contour compensation processing by addition operation of the delayed signal and the synthesized processing signal; and generating from the image luminance component signal CRT display means for generating horizontal and vertical deflection magnetic fields based on the generated horizontal and vertical deflection component signals to perform horizontal and vertical scanning of the beam to display an image, and a position for providing only vertical displacement of the beam of the CRT display means. And a vertical density modulating means for generating a vertical compensation magnetic field based on the vertical contour compensation component signal and superimposing it on the vertical deflection magnetic field. Contour compensation processing apparatus according to the scanning line density modulation of the image, characterized. 2. A delay means for delaying an image luminance component signal for a predetermined time based on a horizontal scanning time and outputting a delay signal, and a synthesis for synthesizing the image luminance component signal and the delay signal, inverting the phase, and multiplying by a predetermined number. Based on a difference signal between the image brightness component signal and the delay signal and a predetermined reference signal, a combination processing unit that outputs a processed signal, and detects the rising and falling brightness changes of the image brightness component signal, Luminance change detection means for obtaining a detection signal according to the detection result, based on the detection signal, a signal obtained by combining the image brightness component signal and the delay signal, the combination processing signal,
A vertical selection unit for selecting and adding and outputting a vertical contour compensation component signal by performing contour compensation processing based on the added output of the synthesized signal and the synthesis processed signal in the signal selection and output means. Contour compensation processing means, CRT display means for generating horizontal and vertical deflection magnetic fields based on the horizontal and vertical deflection component signals generated from the image luminance component signal, and performing horizontal and vertical scanning of the beam to display an image, Vertical density modulation means provided at a position which only gives a vertical displacement of the beam of the CRT display means, and which generates a vertical compensation magnetic field based on the vertical contour compensation component signal and superimposes it on the vertical deflection magnetic field. A contour compensation processing device by scanning line density modulation of a characteristic image.