JPH06139973A - Flat type image display device - Google Patents

Abstract

PURPOSE:To improve the quality of image including irregular brightness by constituting green and blue phosphors of a mixture of a phosphor containing rare earth as a luminous center suitable for use with high current density, and a conventional phosphor to unify an electron beam amount passing an electron beam takeout electrode. CONSTITUTION:The internal surface of a front glass vessel 30 is provided with a screen 30 (b) comprising a red phosphor layer 21, a green phosphor layer 22, a blue phosphor layer 23, a black stripe layer 24 among the layers 21 to 23, and a metal back layer 25 formed behind the layers 21 to 24. In this case, the red phosphor layer 21 comprises 'phosphor Y202S:Eu' and the green phosphor layer 22 comprises 'phosphor Y202S:Tb' and 'phosphor ZnS:Cu, Al' mixed to a ratio of 1 to 1. Furthermore, the blue phosphor layer 23 comprises 'phosphor Y2SiO5:Ce' and 'phosphor ZnS:Ag, Al' mixed to a ratio of 1 to 1. According to this construction, an electron beam amount passing an electron beam takeout electrode can made uniform.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat panel image display device for displaying characters, images and the like, and more particularly to improving the image quality of the image display device.

[0002]

2. Description of the Related Art In recent years, an electron beam has been emitted from a plurality of linear hot cathodes.
A flat panel image display device has been proposed which can display characters, images, etc. by taking out the beam and colliding the electron beam controlled by the electron beam control electrode with the phosphor.

A conventional flat panel image display device will be described below. FIG. 3 shows the configuration of a conventional flat panel image display device.

In FIG. 3, reference numerals 32A to 32D denote a plurality of linear hot cathodes which serve as electron sources of the display device. Reference numeral 31 is a back electrode that functions to direct the electron beam B toward the front surface. Reference numeral 33 is an electron beam extraction electrode for extracting electrons from the linear hot cathodes 32a to 32d. The electrode 33 has a through hole 33a through which the electron beam B passes. Reference numeral 34 is a signal electrode for applying a video signal.
It is composed of a plurality of control electrodes 34a,
A through hole 34a is provided for the passage of the hole B. Reference numerals 35 and 36 denote a first focusing electrode and a second focusing electrode for focusing the electron beam B in the horizontal and vertical directions. Through holes 3 for passing the electron beam B through these electrodes 35, 36.
5a and 36a are provided. 37 is a horizontal deflection electrode for deflecting the electron beam in the left-right direction of the screen. It is composed of a pair of comb electrodes 37a and 37b. The electrodes of the comb-shaped electrodes 37a and 37b constitute a slot 37a through which the electron beam B passes by the mutual electrodes. Reference numeral 38 is a vertical deflection electrode for deflecting the electron beam in the vertical direction of the screen. It is a set of comb electrodes 38
It is composed of a and 38b. The comb-shaped electrodes 38a and 38b form a slot 38a for passing the electron beam B by mutual electrodes. Reference numeral 30 denotes a front glass container, and a screen composed of a red, green, and blue three-color phosphor layer, a black stripe layer provided therebetween, and a metal back layer provided behind them is formed on the inner surface of the container. ing. Reference numeral 39 is a metal plate that serves as a back container. It constitutes a vacuum container together with the front glass container 30.

Further, in the flat panel image display device, it is an indispensable condition to display characters and images on a screen having color reproducibility similar to that of a cathode ray tube for a long time, and the flat panel image display device has a small depth. However, the anodic voltage is reduced to less than half that of the cathode ray tube, and the anodic current is increased as compared with the cathode ray tube. Further, the phosphor used in the conventional flat panel image display device is a phosphor usually used in a cathode ray tube and is called P-22. As typical examples thereof, the red phosphor is Y2O2S: Eu, the green phosphor is ZnS: Cu, and the Al blue phosphor is ZnS: Ag.
There is Al. These red phosphors, green phosphors, and blue phosphors are excellent in initial color reproducibility, but if the flat panel image display device is used for a long time, the degree of deterioration of the luminous efficiency of the phosphors may deteriorate. Different in the phosphors, the deterioration of the red phosphor is about one third as compared with the deterioration of the green phosphor and the blue phosphor, so that the white color reproducibility is deteriorated.

[0006]

SUMMARY OF THE INVENTION In the above conventional configuration,
Since the brightness is modulated according to the time of the pulse applied to the electron beam control electrode, the time for irradiating the fluorescent material is several tens of times that of the cathode ray tube, so that the display time for characters and images is long. In that case, there is a problem that the brightness of the blue phosphor and the green phosphor is greatly reduced, the screen becomes darker, and the reduction rate of the brightness varies depending on the type of the phosphor, resulting in poor white color reproducibility.

In view of the above problems, the present invention provides a conventional flat panel image display device for displaying characters and images of a phosphor and having good color reproducibility.

[0008]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a rare earth element suitable for high current density use of a green phosphor and a blue phosphor whose brightness is significantly reduced on a phosphor surface coated with the phosphor. The fluorescent substance used as the luminescent center and the conventional fluorescent substance are mixed to form a long structure.

[0009]

In the present invention, the color reproducibility can be modified by mixing two kinds of phosphors of at least two colors among red phosphor, extinct phosphor and blue phosphor.

[0010]

【Example】

(Embodiment 1) An embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view of a phosphor screen portion according to an embodiment of the present invention. In the figure, 30 is a front glass container.
On the inner surface of the container, a screen composed of a red phosphor layer 21, a green phosphor layer 22, a blue phosphor layer 23, a black stripe layer 24 provided therebetween, and a metal back layer 25 provided behind them. It is configured. The red phosphor layer 21 is made of "phosphor Y2 O2 S: Eu", and the green phosphor layer 22 is made of "phosphor Y2 O2 S: Tb".
And “phosphor ZnS: Cu, Al” are mixed in a one-to-one manner, and the blue phosphor layer 23 is formed of “phosphor Y2
SiO5: Ce "and" phosphor ZnS: Ag, Al "are mixed in a one-to-one relationship.

In another embodiment, the green phosphor layer 22 is made of "phosphor Y2 SiO5: Tb" and "phosphor Zn."
S: Ag, Al ”in a one-to-one mixture. Figure 2
The initial chromaticity diagram (CIE coordinates) of the green phosphor and the blue phosphor of the flat panel image display device of the present invention is shown in FIG. In the graph of FIG. 2, reference numeral 11 indicates “phosphor Zn,” which is a conventional green phosphor.
S: Cu, Al "coordinates (0.27, 0.60), and 12 is another green phosphor" phosphor Y2 O2 S: T ".
The coordinate "b" (0.35, 0.56) is shown, and 13 is the coordinate (0.33, 0.54) of "phosphor Y2 SiO5: Tb" of another green phosphor. The green phosphor used in the flat panel image display device of the present invention is "phosphor ZnS: Cu, A
1 "and" phosphor Y2 O2 S: Tb "are mixed in a one-to-one manner, the chromaticity shifts to an intermediate position between them and
The coordinates (0.31, 0.58) shown by 4 are obtained.

Another green phosphor used in the flat panel image display device of the present invention is prepared by mixing "phosphor ZnS: Cu, Al" and "phosphor Y2 SiO5: Tb" in a one-to-one manner. , The chromaticity is moved to the intermediate position between them, and the coordinates become 15 (0.30, 0.57). As a result, the flat color image display device has an allowable range of white color reproduction. 16 is a conventional blue phosphor "phosphor ZnS:
The coordinates (0.15, 0.06) of "Ag, Al" are shown, and 1
7 is another blue phosphor "phosphor Y2 SiO5: Ce".
The coordinates (0.20, 0.13) are shown. The blue phosphor used in the flat panel image display device of the present invention is "phosphor ZnS: A".
g, Al "and" phosphor Y2 SiO5: Ce "one to one
By mixing in, the chromaticity moves to the intermediate position between them, and the coordinates (0.17, 0.09) indicated by 18 are obtained. As a result, the flat color image display device has an allowable range of white color reproduction. FIG. 4 shows the result of the life test of the flat panel image display device using the phosphor of the example of the present invention. As can be seen from the figure, the respective phosphors have the same tendency to decrease in brightness. Therefore, white color reproducibility can be realized without performing luminance correction for each color.

The phosphors described in this embodiment may be replaced with other phosphors.

[0015]

According to the present invention, the distribution of the electric field of the electron source of the flat panel image display device becomes uniform, the amount of electron beams passing through the electron beam extraction electrode becomes uniform, and the uneven brightness and the like occur. The image quality of can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view of a fluorescent screen portion according to an embodiment of the present invention.

FIG. 2 is a diagram showing a comparison in luminance reduction between a green phosphor used in a flat panel image display device of the present invention and a green phosphor used in a conventional flat panel image display device.

FIG. 3 is a cross-sectional view showing the structure of a conventional image display device.

FIG. 4 is a diagram showing a result of a life test of a flat panel image display device which is an embodiment of the present invention.

[Explanation of symbols]

 21 Red Phosphor Layer 22 Green Phosphor Layer 23 Blue Phosphor Layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location H01J 29/20 8326-5E

Claims (2)

[Claims] 1. A flat screen is provided on a phosphor screen coated with a phosphor, and a back electrode composed of a conductive plate facing the screen is provided, and the back electrode is placed in a space sandwiched between the back electrode and the screen. In order, a lead electrode made of a conductive plate having a plurality of through holes in the cathode line, a signal electrode, a first focusing electrode and a second focusing electrode, and a horizontal electrode and a vertical electrode made of a plurality of conductive plates located on the same plane. In the flat panel image display device, the flat panel image display device is characterized in that at least two color phosphors among the three color phosphors forming the phosphor screen are mixed with two types of phosphors. 2. The phosphor screen has a blue phosphor as “phosphor Zn”.
S: Ag, Al "and" phosphor Y2 SiO5: Ce "are mixed, and the green phosphor is replaced by" phosphor ZnS: Cu, A ".
2. The flat panel image display device according to claim 1, wherein "1" and "phosphor Y2 SiO5: Tb" or "phosphor Y2 O2 S: Tb" are mixed.