JP2006107747A - Image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable to display an image of natural colors through improvement of color balance of an output image, in a plane image display device having an electron source and a phosphor screen for displaying an image by irradiation of electron beams emitted from the electron source arranged at a given interval. <P>SOLUTION: The image display device includes a first substrate 2 holding an electron beam source, a second substrate 3 holding at least a phosphor layer activating oxide or sulfide of yttrium (Y) with 6.5 to 10 mol% of europium (Eu) as a phosphor layer outputting light of a given color by being irradiated with electron beams outputted from the electron beam source, and opposed to the first substrate at a given interval, and an envelope 5 making up a sealed structure by airtightly sealing the first substrate and the second substrate. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image display device, and more particularly, in an image display device including an electron source and a fluorescent screen that displays an image by irradiation of an electron beam emitted from the electron source in a vacuum vessel. The present invention relates to an image display apparatus capable of improving the color balance of an output image and displaying a natural color image.

  As an image display device that replaces a cathode ray tube (CRT), electron-emitting devices (electron sources) are arranged in a planar and matrix form, and electrons are selectively applied to a planar fluorescent screen (front substrate) facing each other at a predetermined interval. 2. Description of the Related Art Image display devices that display an image by emitting light of an arbitrary color from a phosphor screen by irradiating a line have been developed. This type of image display apparatus is called a field emission display (hereinafter referred to as FED). In addition, among FEDs, a display device using a surface conduction type emitter as an electron source is sometimes classified as a surface conduction type electron emission display (hereinafter referred to as SED). As a generic term, the term FED is used.

  The FED can set the gap between the electron source side substrate and the phosphor screen side substrate to several mm or less, and can be made thinner than a known CRT. The thickness can be equal to or less than that of the flat display device. Therefore, it is expected in terms of weight reduction.

  Further, the FED is a self-luminous type, similar to a CRT (known as a cathode ray tube or a cathode ray tube) or a plasma display, and thus has a feature that the brightness of a display image can be easily obtained.

  On the phosphor screen provided on the inner surface of the front substrate, red (R), blue (B), and green (G) phosphors are arranged in a predetermined size and in a predetermined order. An anode electrode for applying a predetermined sweep voltage to each phosphor is connected to each phosphor on the phosphor screen.

  The substrate on the electron source side has a matrix of scanning lines and signal lines for emitting a predetermined amount of electrons from a previously specified emitter for emitting a phosphor screen facing an emitter at an arbitrary position. It is connected to the.

  In the FED described above, the color of the image light output from each phosphor is slightly different from that of the CRT, and the color range that can be reproduced by the CRT is completely reproduced due to the demand for setting the anode voltage low. I'm not doing it. In addition, the luminance is expected to be larger than CRT.

Regarding the reproducibility of R (red), there is one report using a phosphor that activates yttrium (Y ₂ O ₂ S) with a material based on Eu (europium) (see, for example, Patent Document 1). .
Japanese Patent No. 30322280

The above patent document describes that a filter having an absorption peak at 575 nm ± 20 nm is used while the concentration of yttrium (Y ₂ O ₂ S) is 3 to 9 mol%.

However, the use of the yttrium (Y ₂ O ₂ S) concentration and the filter described in the above document is caused by the difference in color temperature (color of light emitted from the phosphor by the irradiated electron beam). The color reproducibility required for the FED cannot be provided.

  Further, as a problem peculiar to the FED, the luminance of light emitted from the phosphor is governed by the time when the phosphor is irradiated with the electron beam. The color has not been reproduced.

  An object of the present invention is to improve the color balance of an output image in a flat image display device in which an electron source and a fluorescent screen for displaying an image by irradiation of an electron beam emitted from the electron source are opposed to each other at a predetermined interval. It is an object to provide an image display device capable of displaying various color images.

  The present invention holds a first substrate holding an electron beam source, and a phosphor layer that outputs light of a predetermined color when irradiated with an electron beam output from the electron beam source. In the image display device for obtaining an image of an arbitrary color from the phosphor layer, the phosphor layer of the second substrate includes at least oxidation of yttrium (Y). The present invention provides an image display device comprising a phosphor activated with europium (Eu) of an oxide or sulfide, wherein the concentration of the europium is in the range of 6.5 to 10 mol%.

  According to another aspect of the present invention, there is provided a first substrate that holds an electron beam source, and a phosphor layer that outputs light of a predetermined color when irradiated with an electron beam output from the electron beam source, and includes at least yttrium. A second substrate holding a phosphor activated with 6.5 to 10 mol% europium (Eu) of an oxide or sulfide of (Y) and facing the first substrate at a predetermined interval; An envelope that hermetically seals the substrate and the second substrate to provide a hermetically sealed structure, and the phosphor has a luminance that increases stepwise with respect to the amount of electron beams from the electron beam source. An image display device is provided.

  According to another aspect of the present invention, there is provided a first substrate that holds an electron beam source, and a phosphor layer that outputs light of a predetermined color when irradiated with an electron beam output from the electron beam source, and includes at least yttrium. A second substrate holding a phosphor activated with 6.5 to 10 mol% europium (Eu) of an oxide or sulfide of (Y) and facing the first substrate at a predetermined interval; An envelope that hermetically seals the substrate and the second substrate to provide a hermetically sealed structure, and the phosphor has a luminance that increases according to the time of irradiation of electrons from the electron beam source. An image display device is provided.

  According to the present invention, a planar image display device comprising a first substrate holding an electron beam source and a second substrate facing the first substrate, at least an yttrium (Y) oxide or sulfide is provided. By using a phosphor activated by 5 to 10 mol% of europium (Eu), red (color) displayed by the current CRT and vivid red (color) which is not inferior can be obtained.

  As a result, the color balance of the output image is improved, and a natural color display image is obtained.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  1 and 2 show the structure of an FED (Field Emission Display) to which the embodiment of the present invention is applied.

  The FED 1 is opposed to an electron source side substrate (first substrate, hereinafter referred to as a rear panel) 2 having an electron emitting element (electron source or emitter) and a rear panel 2 at a predetermined interval, and is irradiated with an electron beam from the emitter. In this way, a fluorescent surface side substrate (second substrate, hereinafter referred to as a face plate) 3 that outputs fluorescence is provided.

  On the rear panel 2, a plurality of the above-described electron-emitting devices, that is, emitters, are arranged in a planar shape and a matrix shape. The face plate 3 is formed of a plurality of phosphors that correspond to the individual emitters of the rear panel 2 and output light of R (red), G (green), and B (blue), which are three primary colors of additive color mixing. Has been.

  Each of the rear panel 2 and the face plate 3 includes a rectangular rear surface (electron source side) glass substrate 20 and a front surface (phosphor surface side) 30 each having a predetermined area. A predetermined number of electron sources (electron-emitting devices) and phosphors (light-emitting devices) are provided in this portion, that is, the display region equivalent portion (see FIG. 2).

Both substrates 2 and 3, that is, the two glass base materials 20 and 30 are opposed to each other with a gap (interval) of 1 to 2 mm, and by side walls 4 (see FIG. 2) provided at the peripheral portions of both substrates 2 and 3, They are joined together. That is, the FED 1 becomes an envelope 5 having a sealed structure by the two substrates 2 and 3 (base materials 20 and 30) and the side wall 4. The inside of the envelope 5 is maintained at a degree of vacuum of about 10 ⁻⁴ Pa, for example. Between the glass substrates of the rear panel 2 and the face plate 3, a large number of spacers 6 formed in a plate shape or a column shape are arranged in order to withstand the atmospheric pressure acting on each of them in the assembled state as the envelope 5. Has been.

  On one surface of the glass substrate 30 used for the face plate 3, that is, the surface facing inward when assembled as the envelope 5, the above-described phosphors of R, G, B are arranged in a predetermined order. A fluorescent screen 31 is provided. The phosphor screen is provided with a metal back layer (anode electrode) (not described in detail), and the voltage applied to the anode electrode (interelectrode voltage with the electron source) is, for example, 10 to 15 kV.

  As shown in FIGS. 3 and 4, the phosphor screen 31 has three types of phosphors that emit R, G, and B light when electrons emitted from individual emitters of the rear panel 2 collide with each other. Phosphor layers 32 (R), 33 (G), and 34 (B) arranged in terms of area and positional relationship, and a light shielding layer (black mask) that partitions each phosphor layer and that is arranged in a matrix 35.

  On one surface of the glass substrate 20 used for the rear panel 2, that is, the surface facing inward when assembled as the envelope 5, each of the individual phosphor layers 32 of the face plate 3 is described above. In addition, a plurality of emitters (electron sources) 21 for selectively emitting an electron beam are provided. Each emitter 21 is arranged in, for example, 800 columns × 3 and 600 rows corresponding to one unit formed of each pixel, that is, the phosphor layers R, G, and B formed on the face plate 3. The emitter 21 is driven by a matrix wiring or the like connected to a scanning line driving circuit and a signal line driving circuit (not shown).

  In each phosphor layer 32 (R), 33 (G), 34 (B), the longitudinal direction of the face plate 3 (glass substrate 30) is orthogonal to the first direction (X direction) and the X direction (longitudinal direction). When the width direction is the second direction (Y direction), for example, it is formed in a stripe shape extending in the Y direction. Each phosphor layer R (32), G (33), B (34) is arranged with three colors as one unit. The thickness of each phosphor layer R (32), G (33), B (34) is generally 10 μm, although it varies depending on the color.

  The light shielding layer 35 is formed of, for example, a mixture of carbon and a binder material and electrically insulating. The content of the binder material is regulated to 80% at the maximum, for example.

  In the first direction X, the light shielding layer 35 is arranged with a predetermined gap (interval) so that it can be divided into, for example, 800 lines in units of three colors of the phosphor layers R, G, and B. The light shielding layer 35 is provided with a predetermined width (interval) between the phosphor layers of the individual colors, that is, between R and G and between G and B. In addition, the light blocking layers 35 are arranged in the second direction Y, for example, 600 lines. In other words, one set of phosphor layers R, G, and B in three colors is inside the section defined by each line of the light shielding layer 35, that is, in the window (35a) where the light shielding layer 35 does not exist. They are arranged in a predetermined order.

  Although not shown, the entire surface of the phosphor screen 31 covering the phosphor layer regions 32 (R), 33 (G), and 34 (B) partitioned by the light shielding layer 35 is uneven. A smoothing layer that smoothes the phosphor layers 32, 33, and 34 and a metal back layer that functions as an anode electrode are formed. In addition, the voltage (voltage between electrodes between electron sources) applied to a metal back layer (anode) is 10-15 kV, for example.

FIG. 5 shows yttrium oxysulfide (Y ₂ O ₂ S, hereinafter simply referred to as yttrium (or Y, or oxidation), which is a phosphor used for R (32) among the three color phosphor layers shown in FIGS. Alternatively, the concentration when activated with a material having Eu (europium) as a base material is indicated. In FIG. 5, a curve a indicates an example of a suitable concentration used in the embodiment of the present invention suitable for FED, and a curve (dotted line) b indicates an example of a concentration used in a known CRT (comparison). Example). Also, the vertical axis (luminance) in FIG. 5 is a value normalized by “1”.

As shown in FIG. 5, the concentration of Eu contained in the phosphor for R used in the FED (yttrium (Y ₂ O ₂ S)) is higher than that of the phosphor used in the CRT. The preferred concentration partially overlaps with the Eu concentration range shown in Document 1, but is higher than 4.7 to 6.8 mol% described as a preferable concentration range in Document 1, for example, 6 0.5 to 10 mol%.

  In particular, when used in an FED, 8 to 9 mol% is necessary to meet the demand for ensuring emission luminance. Of course, increasing the concentration of Eu is known to cause a decrease in light emission luminance, but the display driving conditions of the FED are compared with those of the CRT as described below with reference to FIG. In this case, it is known that the luminance is difficult to obtain, and the above (Eu) concentration range can be used.

  FIGS. 6A and 6B are schematic diagrams showing the FED display driving method “current value-luminance” and “electron beam irradiation time-luminance” of the present invention. In each of FIGS. 6A and 6B, a curve a indicates a suitable control (drive) example of the embodiment of the present invention suitable for FED, and a curve (dotted line) b indicates a well-known CRT. A general control (drive) example (comparative example) used in FIG. In addition, the vertical axis (luminance) in FIGS. 6A and 6B is a relative value normalized by “1”.

  As shown in FIG. 6A, the luminance of the phosphor of any color used in the FED (here, the Y oxide activated by Eu) is the amount of electron beam supplied to the phosphor layer, that is, the current. Although it is generally proportional to the value, it is not linear but stepwise (a current value that can provide a certain luminance has a predetermined width). This is because, as shown in FIG. 6B, when a current (electron beam) having a constant magnitude is supplied, the luminance depends on the accumulation of the time during which the current is supplied. .

That is, in the phosphor for FED, for example,
A) Anode voltage is lower than CRT, and
B) A large current density is required to output a color (light) of a predetermined color temperature (compared to a phosphor for CRT).
Due to factors such as
C) The amount of energy required for the phosphor to output light (color) having a predetermined color temperature is larger than that of the CRT.
It is recognized that

  On the other hand, in a known phosphor for CRT, light having a predetermined luminance can be obtained by irradiating the phosphor with a certain amount of current (electron beam) for a specified time.

  Therefore, in the FED, it is necessary to increase at least the electron beam intensity (current supply amount) or the electron beam (current) supply time (compared to the CRT). In addition, although it is an experimental value in the prototype FED display device, the amount of current (energy amount) to be supplied to the target phosphor is preferably about 20 to 50% larger than that of the CRT. Of course, it goes without saying that the amount of energy (current amount) depends on the anode voltage or the distance between the emitter and the anode.

  FIG. 7 shows the color (red) obtained by the FED panel having the structure shown in FIGS. 1 to 4 in accordance with the display driving method described above. CIE chromaticity diagram published in Toshio Ishibashi, “Color Receiver”. In the chromaticity diagram of FIG. 7, dotted triangles indicate colors that can be reproduced by a general CRT.

  As shown in FIG. 7, in the red (R) emission of the FED system, which is supposed to fall outside the color range that can be reproduced by the CRT, a bright red that is comparable to the red obtained by the current CRT is obtained. .

  As described above, according to the present invention, a planar image display device comprising a first substrate holding an electron beam source and a second substrate facing the first substrate, at least an yttrium (Y) oxide or By using a phosphor activated with 6.5 to 10 mol% europium (Eu) of sulfide, red (color) displayed by the current CRT and vivid red (color) which is not inferior can be obtained. .

  As a result, the color balance of the output image is improved, and a natural color image is displayed.

  The present invention is not limited to the above-described embodiments, and various modifications or changes can be made without departing from the scope of the invention when it is implemented. Moreover, each embodiment may be implemented in combination as appropriate as possible, and in that case, the effect of the combination can be obtained.

The perspective view which shows FED which concerns on embodiment of this invention. FIG. 2 is a cross-sectional view of the FED taken along line AA in FIG. 1. The top view which shows the fluorescent screen and metal back layer in FED shown in FIG. The top view which expands and shows the fluorescent screen and light shielding layer of FED shown in FIG. The Y 2 _O 2 _S, schematic diagram showing a relationship between concentration and intensity when activated by a material that the Eu as a base material. Schematic which shows an example of the display drive method of FED of this invention. The figure which showed on the chromaticity the color (red) obtained by the FED panel of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Image display apparatus, 2 ... Rear panel (1st board | substrate), 3 ... Face plate (2nd board | substrate), 4 ... Side wall, 5 ... Sealing structure (envelope), 6 ... Spacer, 20 ... (Electron source side) Glass substrate, 21... Electron emitting element (emitter), 30... (Phosphor side) glass substrate, 31... Phosphor surface, 32 .. phosphor layer (R), 33 .. phosphor layer (G), 34. Body layer (B), 35... Light shielding layer (black mask).

Claims (9)

A first substrate holding an electron beam source and a phosphor layer that outputs light of a predetermined color by being irradiated with an electron beam output from the electron beam source are held on the first substrate at predetermined intervals. An image display device that obtains an image of an arbitrary color from the phosphor layer, and an opposing second substrate,
The phosphor layer of the second substrate includes a phosphor in which at least an oxide or sulfide of yttrium (Y) is activated with europium (Eu), and the concentration of the europium ranges from 6.5 to 10 mol%. An image display device characterized in that it is within.   2. The image display device according to claim 1, wherein the phosphor layer having a europium concentration of 6.5 to 10 mol% is used for red display.   The image display device according to claim 1, wherein the concentration of the europium is preferably 8 to 9 mol%.   The image display according to any one of claims 1 to 3, wherein the first substrate and the second substrate are each in a planar shape, and the predetermined interval between the first substrate and the second substrate is 1 to 2 mm. apparatus. 5. The image display device according to claim 1, wherein the first substrate and the second substrate are hermetically sealed by a frame body, and the inside thereof is decompressed to about 10 ⁻⁴ Pa. 6. A first substrate holding an electron beam source;
A phosphor layer that outputs light of a predetermined color by being irradiated with an electron beam output from the electron beam source, and containing at least 6.5 to 10 mol% of an yttrium (Y) oxide or sulfide. A second substrate holding a phosphor activated by europium (Eu) and facing the first substrate at a predetermined interval;
An envelope that hermetically seals the first substrate and the second substrate to provide a sealed structure;
The image display apparatus according to claim 1, wherein the phosphor has a stepwise increase in luminance with respect to an amount of electron beams from the electron beam source.   The image display device according to claim 6, wherein a concentration of the europium is preferably 8 to 9 mol%. A first substrate holding an electron beam source;
A phosphor layer that outputs light of a predetermined color by being irradiated with an electron beam output from the electron beam source, and containing at least 6.5 to 10 mol% of an yttrium (Y) oxide or sulfide. A second substrate holding a phosphor activated by europium (Eu) and facing the first substrate at a predetermined interval;
An envelope that hermetically seals the first substrate and the second substrate to provide a sealed structure;
The image display apparatus according to claim 1, wherein the phosphor increases in luminance according to a time during which the electrons from the electron beam source are irradiated.   9. The image display device according to claim 8, wherein the concentration of europium is preferably 8 to 9 mol%.

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