JPS5911089A - Video display device - Google Patents

Abstract

PURPOSE:To obtain a video display device which is reduced in degree of color shift, by shifting relatively a video signal of three colors in the horizontal direction, by a degree equivalent to the misconvergence. CONSTITUTION:The parallel read-out signals are converted into series signals corresponding to the dot pattern trains which are continuous in terms of time in accordance with clock pulses to obtain video signals VR, VG and VB corresponding to red, green and blue, respectively. These three video signals are supplied to four D-FF20a-23a, two D-FF20b-21b and four D-FF20c-23c respectively. The signals having a shift of a clock period are successively extracted out of each FF and then supplied to signal selecting circuits 24a, 24b and 24c respectively together with video signals. A counter 25 is set by a horizontal synchronizing signal HS, then counts clock pulses CK to generate an address signal showing the position of the screen. A memory 26 stores a data which shows how to shift relatively each corresponding video signal when a luminous point, is obtained at each position corresponding to the above-mentioned address signal.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color video display device, and more particularly to a video display device using a cathode ray tube with an in-line multiple electron gun.

Multi-electron beam color cathode ray tube (hereinafter abbreviated as CDT)
When displaying text or graphic output information from a computer using a 3D electron beam, it is required that the three electron beams coincide exactly at every point on the phosphor surface. This degree of matching is much stricter than the requirements for conventional general color televisions, and the amount of misconvergence is often desired to be 0.2 mm or less. In order to achieve this small amount of misconvergence, conventional C
Extremely high precision was required for the DT and deflection yoke, which was a factor in increasing costs.

The present invention has been made in view of this situation, and its object is to provide a video display device with a t'fh'l configuration and less misconvergence l.

In order to achieve these objects, the present invention configures a deflection yoke to substantially eliminate misconvergence in the vertical direction, and at the same time, it takes time to adjust the phase of the three color video signals to compensate for the misconvergence in the horizontal direction. It is configured to be relatively shifted by a certain amount.

That is, FIG. 1 is a sectional view showing the internal structure of a CDT. Conventionally, electrons are emitted from a gun 1, deflected by a deflection yoke 2, and then passed through a shadow mask 3 to a fluorescent surface 4.
Electron beams of three colors, each corresponding to red, green, and blue, are 5m long.

5b and 5c are all fired simultaneously from the electron gun 1,
Perfect alignment is required on the optical surface 4, which is a factor that requires extremely high precision for both the deflection yoke and the CDT. That is, for a cathode ray tube equipped with an in-line array of electron guns, by combining the horizontal deflection magnetic field with the bin cushion and the vertical deflection magnetic field with the barrel Q deflection yoke, misconvergence can be made virtually zero. It is a well-known fact that it is possible in principle, but in reality, especially in the case of wide-angle deflection, it is difficult to achieve zero misconvergence over the entire screen with good reproducibility.
The current situation is extremely difficult. In this original image, misconvergence at each location on the screen, such as during horizontal deflection, vertical deflection, corner deflection, etc., is related to each other, and depending on the adjustment of the deflection magnetic field distribution, misconvergence at each point on the screen may occur. The problem lies in the inability to change convergence independently.

By the way, instead of reducing the misconvergence to zero over the entire screen, the deflection magnetic field is adjusted so that this residual misconvergence hits a specific intended pattern while allowing a certain amount of misconvergence. This is relatively easy. The present invention has been made with attention to this fact, and firstly uses a deflection yoke having a magnetic field distribution that produces a certain misconvergence pattern.

FIG. 2 shows a residual misconvergence pattern suitable for a video display device according to the invention. In the same figure, 6,
7.8 are red and green on the screen respectively.

It shows a blue emission line, and the convergence of the vertical deflection direction and the horizontal emission line is substantially zero over the entire screen, and the vertical emission line is such that the green emission line is located substantially in the center of the red and blue emission lines, and the relative It can be seen that there is almost no deviation in the center of the screen, and the pattern becomes larger at the edges. It is generally known that such a misconvergence pattern can be easily obtained by using a deflection yoke having a horizontal deflection magnetic field that becomes a comprehensive cushion magnetic field and a vertical deflection magnetic field that becomes a barrel magnetic field.

Therefore, if we observe the misconvergence turn shown in Figure 2 in more detail, the misconvergence at the position indicated by 9, for example, means that the electron beams of each color fired simultaneously from the electron gun at a certain time t This occurs due to a shift in the horizontal direction when the light reaches the light surface.

Accordingly, conversely, by shifting the emission time of the electron beam corresponding to each color, in this example, the city corresponding to the green color,
By emitting the electron beam corresponding to blue earlier and the electron beam corresponding to red later with respect to the child beam, the three bright lines on the screen appear to overlap at position 9, which prevents mistakes. It is possible to obtain the same result as without convergence.

This will be explained in more detail regarding the case where three colors are superimposed on the screen to display white characters, for example, "AN" as shown in FIG. In the figure, 11a to 11g indicate horizontal scanning lines, and black circles indicate bright spots on each scanning line.

Here, for example, in order to obtain the bright spot 12, conventionally, as shown in FIG.
b) to (d) K. Electron beams were emitted using video signal pulses as shown in 13a, 13b, and 13e.

That is, (b), (e), and (d) in the figure show video signal waveforms corresponding to red, green, and blue, respectively, and an electron beam is emitted when the signal is at H level. As is clear from the figure, the phases of the color pulses all match. Note that (-) in the figure indicates a horizontal synchronization signal.

The beams emitted simultaneously in this way do not reach the same point on the fluorescent surface in the presence of misconvergence, and for example, as shown in Figure 5, the beams emitted at the same time do not reach the same point on the fluorescent surface. The bright spots are 14a,
Characters such as 14b and j4c are displayed with color shifts.

In contrast, in the present invention, the positional deviation of the bright spots of the three colors on the fluorescent surface is eliminated by temporally shifting the video signal pulses of the three colors. The signal pulse waveform is shown. Note that (&) in the figure indicates a horizontal synchronizing signal, and (b), (e), and (d) indicate video signal pulses corresponding to red, green, and blue, respectively. As is clear from the figure, the red video signal is delayed in phase by one clock cycle with respect to the green video signal, and the evening video signal is ahead in phase by one clock cycle with respect to the green video signal. It's not true. As a result, on the light surface, for example, 15a
, 15b, and 15e, the red, green, and blue bright spots obtained by the electron beams emitted by the video signal pulses match exactly as shown in FIG.
is obtained. The same applies to other bright spots, and clear character display without color shift can be performed.

FIGS. 8 and 9 show examples of circuits that generate video signals having such relative lead/lag.

In FIG. 8, the dot counter 16 is a circuit that generates a basic clock pulse CK, one clock period of which determines the interval between display dots in the horizontal direction. In response to this clock pulse, the control circuit 1γ outputs a horizontal synchronizing signal H.
8 and a vertical synchronizing signal S, and the dot memory 18a.

Controls reading and writing of data to and from 18b and 18c. These dot memories 18a, ieb,
1Bctrl, corresponding to red, green, and blue, respectively, and data indicating dot patterns to be displayed are stored.

The data read out from these dot memories 18a, 18b, 18c is for eight consecutive dots on a horizontal scanning line at the same time. Parallel-serial converter 19m, 19b,
19c converts this parallel read signal into a clock pulse C.
KK is converted into a serial signal corresponding to a temporally continuous dot pattern sequence, and video signals VR, VC, and VB corresponding to red, green, and blue are generated, respectively.

The video signal VR is transmitted through four D-flip-flops 20m, 21m, 22m, 23 shown in FIG.
m is input into a series circuit. Signals shifted by one clock period are sequentially extracted from each flip-flop and input to the signal selection circuit 24a together with the original video signal. In this case, the input signal R+2 corresponding to the original video signal VR is transmitted through two stages of 7-lip frogs 20m and 21a.
The optical video signal is an optical video signal that is advanced by two clock cycles with respect to the input signal R obtained through the flip-flop 20 of one stage.
The input signal R44 obtained through & is an optical video signal that is one clock cycle ahead of the input signal RO. On the other hand, the three-stage 7-lip flop 20m, 21m, 22m
The input signal R-1 obtained through the flip-flop 21a and the input signal R- obtained through the further flip-flop 21a.
2 is 1 clock and 2 clocks respectively for input signal RQ.
The optical video signal is delayed by a clock cycle.

Similarly, the evening video signal VB is input to a series circuit consisting of four D-flip-flops 20c, 21e, 22e, 23e, from which it leads to and from the input signal BO each by 1.2 clock periods. The input signals B+11 and B+2 as well as the input signals B-1+ and B-2, each delayed by 1 and 2 clock cycles, are input to the signal selection circuit 2.
4c.

On the other hand, the line video signal VC is passed through a series circuit consisting of two D-flip-flops 20b and 21b to an input signal G delayed by two clock periods with respect to the original signal, and then outputted to the signal selection circuit 24b. Input to each input terminal.

On the other hand, in FIG. 9, the counter 25 receives the clock pulse CK after being set by the horizontal synchronizing signal H8.
This generates an address signal X-ADDR indicating the position from the left edge of the screen and sends it to the memory 26.

The memory 26 stores data indicating how to relatively shift each corresponding color video signal when obtaining a bright spot at each position corresponding to the address signal.

That is, when a misconvergence pattern is shown in which the red bright line 6 is shifted to the left and the blue bright line 8 is shifted to the right with respect to the green vertical bright line 1 as shown in FIG. In the case of a position included in area I, an output signal ZONEQ indicating this is sent to each signal selection circuit 24m, 24b, 24c.
is applied to the select terminal s, ) of At this time, each of the signal selection circuits 24m, 24b, and 24c selects and outputs the input signal RO+GO+BO, respectively. Therefore, these output signals are amplified to finally obtain video signals R, G, and B that drive the electron gun. In this case, each corrected video signal R, G.

B is delayed by two clock cycles with respect to the original video signals VR, VG, and VB, but there is no phase difference between them.

On the other hand, if the position is t6 included in the region (2) near the edge, the output signal ZONEI is output to each signal selection circuit 24.
a, 24b, 24c are provided with select terminals SIK, and each signal selection circuit 24a, 24b, 24c is connected to R-1.
Selectively output r GO+ 13+t. in this case,
The corrected red image signal R-1 is delayed by one clock period with respect to the green image signal GO, and the blue image signal B+1 is conversely advanced by one clock period, and an electron beam is emitted by these video signals. Particularly, the deviation d of the bright line in region 12 is almost eliminated.

Next, in the case of the region TJI at the end where the deviation of the bright line is large, the output signal ZONE2 is outputted, and each of the signal selection circuits 24a, 24b, and 24e accordingly receives the R-
2+ Output GOrB+2. As a result, the bright line in area Is the deviation also #'J? '! It can be resolved.

As explained above, according to the present invention, the deflection direction is configured so as to obtain a misconvergence pattern in which the horizontal lines are substantially aligned, and the video signals of three colors are By relatively shifting the color by 100 degrees, it is possible to realize a video display device with a simple configuration and less color shift with good reproducibility, which is an excellent effect.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the structure of a cathode ray tube used in a video display device, FIG. 2 is a diagram showing an example of a misconvergence pattern, and FIGS. 3 and 4 (a) to (d). Figure 5 is a diagram for explaining the relationship between color fading on the screen and video signals in a conventional video display device, Figure 6 (nose)
-(d) and FIG. 7 are diagrams for explaining the improvement status of video signals and color shift in the video device according to the present invention, and FIGS. FIG. 3 is a diagram illustrating an example of a circuit for shifting the target. 1...electron gun, 2...deflection yoke, 20&~2
0d, 21a to 21d, 22m, 22e,
23m, 23c...D-flip-flop. Figure 2 m, If J, It
MFigure 3 Figure 7 Figure 4 Figure 5 Figure 6 Figure 7 Figure 2 Figure 8

Claims (1)

[Claims] A color cathode ray tube equipped with an in-line 3 electron gun, a deflection yoke with a magnetic field distribution that virtually eliminates vertical misconvergence, and a three-color video signal input that is relative by an amount corresponding to horizontal misconvergence. and a circuit for generating a phase-shifted corrected video signal.