JP2000032484A - Image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image display device, capable of easily reproducing the white balance of the overall screen or each luminance uniformizing section of the screen in the same state as an initial stage, even when the balance of the light emission luminance of respective colors changes with time. SOLUTION: In the video signal correction circuit of this image display device, corresponding to the information of an irradiation electric charge total amount inputted from an irradiated electric charge total amount value generator 65 and luminance uniformizing information for each luminance uniformizing section inputted from a memory 55, the relation of the light emission luminance of a beam spot to the irradiation time of an electron beam can be changed freely.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device used for a color television receiver, a terminal display of a computer, and the like.

[0002]

2. Description of the Related Art FIG. 7 is an exploded perspective view of a conventional image display device. The image display device according to the related art includes a rear electrode 1, a line cathode group 2 as a beam source, and a rear electrode 1 in order from the rear (left side in the figure) to the front (right side in the figure).
A beam extraction electrode 3, a control electrode 4, a focusing electrode 5, a horizontal deflection electrode 6, a vertical deflection electrode 7, and a screen plate 8 are arranged, and these components are housed in a vacuum vessel (not shown). ing.

A group of line cathodes 2 as a beam source is composed of a plurality of line cathodes stretched in the horizontal direction so as to generate an electron beam distributed linearly in the horizontal direction. Are provided at a predetermined pitch. As an example, the pitch between the vertical line cathodes is 5.5 mm,
The number of linear cathodes is 19. 2a to 2
s. However, FIG. 7 shows seven linear cathodes 2a to 2g for easy viewing. These linear cathodes 2a to 2a
s is formed, for example, by coating an oxide cathode material on the surface of a tungsten wire having a diameter of 10 to 30 μm. Also, the distance between the line cathodes cannot be freely increased,
It is regulated by the distance between a vertical deflection electrode 7 and a screen 8 described later. Further, as will be described later, these linear cathode groups 2 are scanned from the upper linear cathode 2a to the lower linear cathode 2s so as to sequentially emit an electron beam for a predetermined time.

The back electrode 1 has a function of suppressing generation of an electron beam from a line cathode other than the line cathode being driven, and pushing the electron beam only in the anode direction. Although the vacuum vessel is not shown in FIG. 7, the back electrode 1 may have a structure also serving as the back face of the vacuum vessel.

The beam extraction electrode 3 is formed by using a conductive plate 11 having a plurality of through holes 10 formed therein, and divides an electron beam emitted from the linear cathode group 2 into a plurality of pieces through the through holes 10 in the horizontal direction. It has a function to take out. Therefore, the through hole 10 of the conductive plate 11 is
a to 2 s, and are provided at regular intervals in the horizontal direction.

The control electrode 4 is composed of a plurality of vertically long conductive plates 15 having through holes 14 at positions opposed to the respective linear cathodes 2a to 2s. It is arranged in. For example, 107
The control electrodes 4 are configured by arranging the conductive plates 15.
However, in FIG. 7, the eight conductive plates 15
Only is drawn. The control electrode 4 controls the passing amount of each of the electron beams divided in the horizontal direction by the beam extraction electrode 3 in correspondence with each picture element of the video signal, and in synchronization with the later-described horizontal deflection timing. .

The focusing electrode 5 is constituted by using a conductive plate 17 in which a plurality of through holes 16 are formed, and has a function of focusing an electron beam. The through hole 16 of the focusing electrode 5 is formed at a position facing the through hole 14 provided in the control electrode 4.

The horizontal deflection electrode 6 includes a pair of vertically extending conductive plates (electrode portions) 18 a to 1 arranged so as to sandwich the vertical arrangement of the through holes 16 formed in the focusing electrode 5.
8d, 18'a to 18'd, and a voltage for horizontal deflection is applied to each pair of conductive plates. Although only four pairs of conductive plates are illustrated in FIG. 7, more conductive plates are actually arranged. The plurality of pairs of electrode portions 18a to 18d and 18'a to 18'd
107 electron beams are divided per horizontal scanning line (FIG. 7 shows a state in which eight beams are divided into four), and each division is independently deflected in the horizontal direction. ), G (green) and B (blue) phosphors are sequentially irradiated to emit light. Also, in this configuration,
Each electron beam is deflected by two trios.

The vertical deflection electrode 7 is constituted by using a pair of comb-shaped conductive plates 19 and 19 ′ arranged in the horizontal direction at intermediate positions in the vertical direction of the through holes 16 formed in the focusing electrode 5. Have been. An electron beam is deflected in the vertical direction by applying a vertical deflection voltage to both conductive plates 19 and 19 '. In this configuration, one pair of comb-shaped conductive plates 19, 19 '(vertical deflection electrodes 7) is used.
The electron beam generated from the line cathode is deflected by 12 lines in the vertical direction, and 228 horizontal scanning lines are drawn on the screen 8 in the vertical direction.

As described above, in the image display device according to the prior art, the horizontal deflection electrode 6 and the vertical deflection electrode 7 are each formed of a comb-like electrode plate. In this image display device, the distance from the vertical deflection electrode 7 to the screen 8 is set longer than the distance between the horizontal deflection electrode 6 and the vertical deflection electrode 7. This is because it is possible to irradiate a predetermined position of the screen 8 with the electron beam with a small deflection amount, whereby the deflection distortion can be reduced both horizontally and vertically.

The screen 8 is formed by applying a phosphor 20 in a stripe shape on the back surface of the glass plate 21 (on the side irradiated with the electron beam). Further, a metal back and carbon are also applied to the back surface of the glass plate 21 (not shown). Further, the phosphors 2 are irradiated such that the electron beam passing through one through hole 14 of the control electrode 4 and deflecting in the horizontal direction irradiates the phosphor pairs of three colors of R, G, and B for two trios.
0 is formed, and is applied on the back surface of the glass plate 21 in a stripe shape in the vertical direction. In this FIG.
The broken lines drawn on the screen 8 indicate the vertical divisions displayed corresponding to the respective line cathode groups 2 including a plurality of line cathodes, and the two-dot chain line indicates the control section including the plurality of conductive plates 15. The horizontal division displayed corresponding to each of the electrodes 4 is shown.

FIG. 8 is an enlarged view of one section partitioned by a broken line and a two-dot chain line in FIG. As shown in FIG. 8, one section of the screen 8 has two trios of R, G, and B phosphors in the horizontal direction and a width of 12 lines in the vertical direction. The size of one section (one unit) is, for example, 1.28 mm in the horizontal direction and 5.5 mm in the vertical direction.

The R, G, and B phosphors are provided for two trios for one through-hole 14 of the control electrode 4, but may be composed of one trio or three or more trios. However, one trio or three or more R, G, B video signals are sequentially applied to the control electrode 4, and it is necessary to perform horizontal deflection in synchronization therewith.

As described above, this type of image display device is
A minute image display unit (1.28 mm ×
5.5 mm) are arranged vertically and horizontally in a multi-beam spot display device that displays one image as a whole. Therefore, if there is a variation in the flow rate of the electron beam that turns on each image display unit, the overall The image quality is not uniform. Also, if there is a variation in the interval between adjacent lines, if the interval is larger than other parts, the area is darker,
Conversely, if it is small, it will be bright and the image quality will not be uniform. Further, when the relationship between the electron beam irradiation time and the emission brightness of the beam spot is non-linear or different between the three colors of R, G, and B, the image quality is made uniform at a certain level of brightness to adjust the white balance. Is performed, the uniformity of image quality and white balance are lost at other luminance levels. Normally, the video signal is modulated in consideration of the relationship between the electron beam amount and the luminance of an image display device using a CRT (hereinafter referred to as gamma correction).
If the relationship between the electron beam and the brightness of this image display device is different from that of an image display device using a CRT, an image equivalent to that of an image display device using a CRT cannot be reproduced.

Therefore, the inventors have disclosed Japanese Patent Application Laid-Open No. 7-1938.
The problem described above has been solved by using a circuit as described in Japanese Patent Publication No. 29-29. FIG. 6 shows a block diagram of a video signal correction circuit of a conventional image display device. 71 to 73 are R,
A / D converter for converting the analog video signal for each of G and B colors into a digital signal. 75 is information on luminance distribution for each image display unit in the image display device and information on luminance distribution for each of a plurality of divided lines. Are multiplied and recorded; 74 is an address generation circuit for controlling the memory 75; 76 to 78 are inverse γ correctors for inverse γ (gamma) correction of video signals; 79 to 81 are modulated to luminance And 82 to 84 are light emission luminance conversion devices for converting the video signal into a linear relationship with the light emission luminance of the beam spot of the image display device of the present invention.

The information on the luminance distribution recorded in the memory 75 is obtained as follows. First, a video signal having a certain size is input to the image display device. At this time, if the flow rates of the electron beams in the image display unit constituting the image display device are completely the same, and if the line intervals are completely equal, a uniform brightness distribution can be obtained throughout,
If there is a variation in the flow rate of the electron beam in the image display unit or if the intervals between the lines are not uniform, a portion where the luminance is not uniform occurs. First, the luminance at this time is measured for each image display unit, and the data corresponding to the negative of the luminance distribution for each unit (a bright part is small and a dark part is large) is recorded in the memory 75. Next, each line is divided into a plurality of sections in the vertical direction, the luminance is measured for each section of each line, and data corresponding to the negative of the luminance distribution of each section of each line is also multiplied and recorded in the memory 75. As a result, in the memory 75, information divided into luminance equalization sections at the maximum of every two trios in this case is recorded. Hereinafter, the information on the luminance distribution for each image display unit and the information on the luminance distribution for each line in the image display device will be collectively referred to as luminance uniformity information.

The address generating circuit 74 includes a memory 75
Are synchronized with the horizontal synchronizing signal h and the vertical synchronizing signal v so that the data and the image display device always correspond one to one. The inverse gamma correctors 76 to 78 will be described. Since the video signal is subjected to gamma correction of 1 / 2.sup.2 in consideration of the relationship between the current and the luminance of the image display device using the cathode ray tube, The digital video signal is subjected to a 2.2 power conversion.

The multipliers 79 to 81 further control the memory 7
The video signal is modulated by the information of luminance equalization 5. Then, the video signal is converted in consideration of the relationship between the video signal unique to the image display device and the light emission luminance of the beam spot (for each of R, G, and B colors). Specifically, the nonlinear relationship for each color is formulated, its inverse function is obtained, the video signal is converted based on this function, and the actual irradiation time of the electron beam is obtained.

In summary, the video signal after AD conversion is first subjected to inverse conversion of gamma correction, is then multiplied by luminance uniformity information from the memory 75, and finally, the light emission characteristics of each color of the image display device are determined. Receive the conversions considered. The above problem is solved by performing these three signal processes.

[0020]

However, in the case of a phosphor light emitting system such as the image display device of the present invention, the brightness of the phosphor is reduced and the glass material of the screen is browned according to the total amount of irradiation charge. Due to the phenomenon (the glass surface in contact with the phosphor layer changes to a reddish brown color)
The balance of the light emission luminance of each color changes with time. In particular, the emission luminance of blue and green is significantly reduced.

The lowering of the brightness of the upper phosphor and the occurrence of the browning phenomenon cause a problem that the initially adjusted white balance is lost and the color temperature tendency of the entire screen generally changes in the red direction. Further, as described above, since the cancellation of the brightness non-uniformity is realized by adjusting the irradiation time of the electron beam, the amount of decrease in the brightness differs in proportion to the irradiation time, and the color temperature of each of the brightness uniform sections on the screen is different. There was a problem that a difference in change occurred. The white balance of the entire screen can be returned to its original state by performing readjustment using a dedicated device for adjustment again. However, from the viewpoint of service-free, it is desirable that the white balance can be adjusted alone.

The present invention has been made to solve the above-mentioned problems, and the balance of the emission luminance of each color changes with time due to the reduction in the luminance of the phosphor and the browning phenomenon of the glass material as the screen. It is another object of the present invention to provide an image display device capable of easily reproducing a white balance for the entire screen or for each section of the screen in which the luminance is equalized to the same state as the initial state.

[0023]

In order to achieve the above object, an image display apparatus according to the present invention divides a screen on a screen into a plurality of sections in a horizontal and a vertical direction, and a group of electron beams irradiating each section. By irradiating the phosphor applied on each section, when forming an image by a number of beam spots formed on the screen, the emission brightness of the beam spot on the screen, the irradiation time of the electron beam, Having a means for changing the relationship according to the brightness uniformity information for canceling the brightness non-uniformity and the information on the total charge amount of the electron beam irradiated to the phosphor for each brightness uniformity section. I do.

According to this image display device, even if the balance of the emission luminance of each color changes with time due to the decrease in the luminance of the phosphor and the browning phenomenon of the glass material as the screen, the beam spot of each luminance uniform section is changed. Since the relationship between the emission luminance and the irradiation time of the electron beam can be changed according to the luminance equalization information for canceling the luminance non-uniformity and the information of the total charge of the electron beam irradiated to the phosphor, the entire screen or The white balance for each trio of the screen can be easily reproduced in the same state as the initial state.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. The image display device according to the present invention has a correction circuit having basically the same configuration as the video signal correction circuit of the conventional image display device shown in FIG. In describing an embodiment of the present invention, a description that overlaps with that of the related art will be omitted.

FIG. 1 is a block diagram of a video signal correction circuit of an image display device according to an embodiment of the present invention. The variable light emission brightness converters 62 to 64 are converters for converting a video signal into a linear relationship with the brightness of the beam spot of the image display device of the present invention, and information on the total amount of irradiation charges input from the total irradiation value generator 65. In addition, the relationship between the light emission luminance of the beam spot and the irradiation time of the electron beam can be freely changed in accordance with the information on the luminance uniformity input from the memory 55.

The irradiation charge total value generator 65 generates information on the total charge of the electron beam that has hitherto been irradiated on the phosphor. Although the total charge can be measured using a general sensor, the user may set information corresponding to the total charge visually.

Basically, the deviation of the white balance is caused by the fact that the amount of decrease in luminance from the initial adjustment state differs for each color. Therefore, the light emission luminance ratio of each color in the initial stage may be the same over time. The method will be described below.

The ratio of the amount of decrease in luminance of each color can be easily determined by conducting an experiment in advance depending on the phosphor or glass material to be used. Therefore, the ratio is first stored. Further, the parameter of the change with time is determined by information on the luminance uniformity of each luminance uniforming section and information on the total charge amount of the electron beam applied to the phosphor so far.

Therefore, the variable light emission luminance converters 62 to
64, the information of the luminance uniformization coefficient K is inputted from the memory 55 for each luminance uniforming section, and the information of the total irradiation charge amount S is input from the total irradiation charge value generator 65, and the light emission luminance of the beam spot is inputted. The deviation of the white balance can be corrected by changing the relationship between the time and the irradiation time of the electron beam as needed.

Next, the operation of the variable light emission luminance converters 62 to 64 will be described with reference to FIGS. In general, the reduction in luminance of the phosphor is larger in B and G than in R. Regarding the browning phenomenon of the glass material that is the screen (the phenomenon in which the glass surface in contact with the phosphor layer changes to a reddish brown color), the transmittance of B and G greatly decreases.
Therefore, in order to balance the light emission luminance, R
Must be attenuated. A specific attenuation method will be described with reference to FIG.

The relationship between the light emission luminance of the beam spot of the variable light emission luminance converter 62 for processing the video signal of R and the irradiation time of the electron beam is calculated based on the information of the total amount S of irradiation electric charges with respect to the maximum light emission luminance LR. The correction is performed using the correction coefficient function f (S) so that the maximum light emission luminance becomes f (S) × LR. That is, the maximum value of the video signal processed in the previous block is made to correspond to f (S) × LR, and the irradiation time range of the electron beam is changed from TR to TR ′.
By doing so, it is possible to attenuate only the emission luminance of R. Correction coefficient function f for irradiation charge total amount S
FIG. 4 shows an example of the change of (S). Further, the same method is used to attenuate the emission luminances of B and G in order to finely balance the emission luminance.

Further, since the cancellation of the brightness non-uniformity is realized by adjusting the irradiation time of the electron beam,
The ratio of the luminance reduction amount varies in each luminance uniforming section. Therefore, next, a difference is made between the light emission luminances of B and G, which have a large luminance reduction amount, based on the information of the luminance uniformity, so that the initial light emission luminance ratio can be reproduced. This will be specifically described with reference to FIG. Here, G will be described as an example. The relationship between the light emission luminance of the beam spot of the variable light emission luminance converter 63 that processes the G video signal and the irradiation time of the electron beam is expressed by comparing the information of the irradiation charge total value S and the luminance equalization coefficient K with respect to the maximum light emission luminance LG. Based on the information, the correction coefficient function g (S,
K), and the maximum emission luminance is g (S, K) × LG.
So that That is, the maximum value of the video signal processed in the previous block is made to correspond to g (S, K) × LG, and the irradiation time range is changed from TG to TG ′. In this manner, the emission luminance of G can be attenuated based on the total amount S of irradiated charges and the luminance uniformization coefficient K. Blue is attenuated in the same manner. Correction coefficient function g for irradiation charge total amount S and luminance uniformity coefficient K
FIG. 5 shows an example of the change of (S, K).

[0034]

As described above, according to the present invention,
Even if the emission luminance balance of each color changes with time due to the decrease in the luminance of the phosphor and the browning phenomenon of the glass material that is the screen, the white balance of the entire screen or the luminance uniformity section of the screen is easily the same as the initial state. Thus, an image display device that can be reproduced at a high speed can be obtained.

More specifically, the relationship between the emission brightness of the beam spot and the irradiation time of the electron beam is determined for each of the brightness uniforming sections by the information for canceling the brightness non-uniformity and the electron beam irradiation to the phosphor. There is provided a means that can be changed according to the information on the total charge amount. Thus, even if the balance of the emission luminance of each color changes with time, the white balance for the entire screen or for each luminance uniform section of the screen can be easily reproduced in the same state as the initial state.

[Brief description of the drawings]

FIG. 1 is a block diagram of a video signal correction circuit of an image display device according to the present invention.

FIG. 2 is a view for explaining the operation of a variable light emission luminance converter for processing an R signal of the video signal correction circuit of FIG. 1;

FIG. 3 is a view for explaining the operation of a variable light emission luminance converter for processing a G signal of the video signal correction circuit of FIG. 1;

4 is a diagram illustrating an example of a correction coefficient function f (S) of a variable light emission luminance converter that processes an R signal of the video signal correction circuit of FIG. 1;

5 is a diagram illustrating an example of a correction coefficient function g (S, K) of a variable light emission luminance converter that processes a G signal of the video signal correction circuit of FIG. 1;

FIG. 6 is a block diagram of a video signal correction circuit of an image display device according to the related art.

FIG. 7 is an exploded perspective view of an image display device according to the related art.

FIG. 8 is a diagram showing a section 1 indicated by a broken line and a two-dot chain line in FIG.
Enlarged view of the phosphor screen in one section

[Explanation of symbols]

 51, 52, 53, 71, 72, 73 A / D converters 54, 74 Address generation circuits 55, 75 Memory 56, 57, 58, 76, 77, 78 Inverse gamma correctors 59, 60, 61, 79, 80 , 81 Multipliers 62, 63, 64 Variable emission luminance converters 82, 83, 84 Emission luminance converters 65 Irradiated charge total amount generator

Claims (1)

[Claims] 1. A screen on a screen is divided into a plurality of sections in the horizontal and vertical directions, and an electron beam group for irradiating each section is coated with three kinds of phosphors of R, G, and B applied on each section. In an image display device that forms an image with a large number of beam spots formed on the screen by irradiating light, the relationship between the emission brightness of the beam spot and the irradiation time of the electron beam is determined for each brightness uniforming section. An image display device comprising: means for changing in accordance with luminance uniformity information for canceling luminance non-uniformity and information on the total amount of charge of the electron beam applied to the phosphor.