JP2001112013A - Color image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color image display device that enhances a color reproduction region by eliminating color mixture. SOLUTION: A mixed phosphor on a fluorescent screen 2 of a monochrome cathode ray tube 1 consists of a blue luminescence phosphor for a wavelength band of 450-480 nm, a green luminescence phosphor for a wavelength band of 520-550 nm, and a red luminescence phosphor for a wavelength band of 600-630 nm. Color polarizing filters 6, 8, 10 have a characteristic of a transmittivity of 20% or below in the absorption axis for wavelength bands of wavelength of 550 nm or below for the filter 6, a wavelength of 520 nm or over and a wavelength of 710 nm or below for the filter 8, and a wavelength of 600 nm or over for the filter 10 respectively. The luminescence of the fluorescent screen 2 in the overlapped area of transmission spectrums between the color polarizing filters 6, 8, 10 can be suppressed very low to suppress intrusion of unnecessary spectrums and to prevent color mixture thereby suppressing deterioration in the color purity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a color image display device in which a monochrome cathode ray tube and a liquid crystal color shutter are combined.

[0002]

2. Description of the Related Art At present, as color image display devices, for example, color cathode ray tubes, liquid crystal displays, plasma displays, field emission displays (F
ED) is used. In each of these color image display devices, a color-added portion of red, green and blue is separately formed as one pixel by a method called spatial addition, and red, green and And blue are changed in intensity to be individually colored to recognize colors that are spatially separated.

However, in such a spatial additive display system that separates the red, green, and blue light-emitting portions, a non-light-emitting area is provided in the light-emitting surface in order to prevent color mixing in the individual light-emitting areas of red, green, and blue. Are formed, the light emitting region becomes discontinuous, and the display device does not have continuity of pixels, and there is a great limitation on miniaturization.

As a method for solving such a problem, for example, there is a so-called field sequential system in which white light is temporally separated into red, green, and blue to obtain a predetermined color. In the field sequential system, the same area is used. Red, green and blue are emitted simultaneously, and red, green and blue are separated temporally and mixed again on the retina, enabling pixelless images and continuous, high-definition like silver halide photography Image.

As the field sequential system, for example, a configuration described in Japanese Patent Application Laid-Open No. Hei 10-79904 is known. Japanese Patent Application Laid-Open No. Hei 10-79904 discloses that a cathode ray tube (CRT) and a liquid crystal color shutter are combined, and white light from the cathode ray tube is separated into three colors of red, green and blue by using a color shutter and then mixed. The configuration is described.

[0006] A terbium-activated yttrium oxysulfide phosphor, which emits white light and is called P45, is used for the phosphor screen of the cathode ray tube. Although this phosphor is a single phosphor, it has a light-emitting component in any of the spectral regions corresponding to red, green, and blue, and thus displays red, green, and blue colors by combining with a liquid crystal color shutter. It is possible.

[0007]

On the other hand, as a phosphor obtained by mixing red, green and blue phosphors, for example, P2
A phosphor mixed with a silver-activated zinc sulfide phosphor emitting blue light, a copper-activated zinc sulfide phosphor emitting green light, and a europium-activated yttrium oxysulfide phosphor emitting red light, which is referred to as No. 2, can be considered.

Various combinations can be considered for the liquid crystal color shutter used in the color image display device having such a configuration depending on the number and type of color polarizing plates used. However, the configuration is simple and the light transmittance is relatively high. For example, a configuration including three color polarizing plates of red, green, and blue and two liquid crystal shutters called a π cell can be considered.

Further, a color polarizing plate is generally oriented by stretching a resin obtained by dyeing a resin with a dichroic dye.
In general, the transmission spectrum of a dye is broad, so that spectral overlap occurs between red, green and blue color polarizers.

Therefore, when a liquid crystal color shutter having the above-described three color polarizers of red, green, and blue is used, for example, when displaying red, the light emission of the phosphor transmitted through the red color polarizer. In addition, the emission of the phosphor that has passed through the portion where the spectra of the green and blue color polarizing plates overlap is also mixed. Especially P22
A phosphor with a band-like emission spectrum, such as a mixture of red, green and blue phosphors, or an emission part with various wavelengths, such as a P45 phosphor, which overlaps the spectrum of a color polarizer. In the case of phosphors that emit light, unnecessary spectra due to the overlap of the spectrum of the color polarizer with the spectrum that should be displayed are mixed, and the color purity of the three primary colors of red, green and blue is significantly reduced. Resulting in.

As described above, in the conventional combination of the liquid crystal color shutter having three color polarizers and the phosphor of the cathode ray tube, there is an overlap between the colors of the transmission characteristics. There is a problem that the transmitted color is mixed with the selected color, thereby greatly reducing the color purity and narrowing the color reproduction range.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a color image display apparatus in which color mixture is eliminated and the color reproduction range is enlarged.

[0013]

SUMMARY OF THE INVENTION The present invention provides a blue light emitting phosphor whose phosphor surface is activated by thulium, a green light emitting phosphor activated by at least one of holmium and erbium, and an europium activated phosphor. A monochrome cathode ray tube which has a mixed phosphor of the red light emitting phosphor and displays an image, and a liquid crystal color shutter which separates an image displayed by the monochrome cathode ray tube into colors.

A mixture of a blue light-emitting phosphor whose phosphor surface is activated by thulium, a green light-emitting phosphor activated by at least one of holmium and erbium, and a red light-emitting phosphor activated by europium The phosphor is
Since there are few light emission components existing in the overlapping portions of the transmission spectra of the liquid crystal color shutter, the display colors of red, green and blue are improved.

The liquid crystal color shutter has three color polarizers of blue, green and red, and two liquid crystal shutters located between the three color polarizers, and the blue polarizer has a wavelength of 520 nm or more. 710 nm or less, the green polarizing plate
480 nm or less and 600 nm or more, the red polarizing plate is
In each wavelength region of 550 nm or less, the transmittance of the absorption axis is 20% or less, and the emission component existing in the overlapping portion of the transmission spectrum of the color polarizing plate is reduced.

Further, the blue light emitting phosphor, the green light emitting phosphor and the red light emitting phosphor are all rare earth oxysulfide phosphors.

Further, in the blue light emitting phosphor, the green light emitting phosphor and the red light emitting phosphor, A is at least one of Y, La, Gd and Lu, and B is Tm, Ho,
Any of Er and Eu, 0.0001 ≦ x ≦ 0.1
Where (A _{1− x} , B _x ) ₂ O ₂ S is used, and in this case, since there are less light emission components existing in the overlapping portion of the transmission spectrum of the liquid crystal color shutter,
It is preferable to improve the mixture of display colors of red, green and blue.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A color display image device according to an embodiment of the present invention will be described below with reference to the drawings.

The color image display device shown in FIG. 1 has a monochrome cathode ray tube (CRT) 1 serving as a white light source. The monochrome cathode ray tube 1 has a phosphor screen 2 for emitting white light. A liquid crystal color shutter 3 is provided on the front surface. The phosphor screen 2 is coated with a mixed phosphor, and the mixed phosphor is caused by a blue light-emitting phosphor having a blue component around 450 nm to 480 nm due to thulium ions, holmium ions or erbium ions. A green light-emitting phosphor having a green component having a wavelength of about 520 nm to about 550 nm, and a wavelength of 6 due to europium ions.
It has a red light-emitting phosphor having a red component having a wavelength of from about 00 nm to a wavelength of about 630 nm, and has the characteristics of an emission spectrum in which the intensity of other light-emitting components is extremely low. Further, in the blue light emitting phosphor, the green light emitting phosphor and the red light emitting phosphor, A represents at least one of Y, La, Gd and Lu, B represents Tm, Ho, Er and Eu, and 0.0001. When ≦ x ≦ 0.1, all are (A _1-x , B _x ) ₂ O ₂ S rare earth oxysulfide phosphors. Further, an image processing circuit 4 is connected to the monochrome cathode ray tube 1, and a liquid crystal cell driving circuit 5 is connected to the liquid crystal color shutter 3 and the image processing circuit 4.

The liquid crystal color shutter 3 polarizes white light into red and cyan from the side of the monochrome cathode ray tube 1 and has a transmittance of an absorption axis of 20 in a wavelength range of 550 nm or less.
%, A color polarizing filter 6 as a red color polarizing plate, a π cell 7 as a liquid crystal shutter, a white and blue polarized light having a transmittance of an absorption axis of 20% or less in a wavelength range of 520 nm to 710 nm. A color polarizing filter 8 as a blue color polarizing plate, a π cell 9 as a liquid crystal shutter, a green color which is polarized to white and green and has a transmittance of an absorption axis of 20% or less in a wavelength range of 480 nm or less and 600 nm or more. A color polarizing filter 10 as a color polarizing plate is sequentially arranged. The red color polarizing filter 6 is a C.I. I. Direct Red
81 and C.I. I. Direct Orange 39 is dyed and stretched using a dye solution containing a predetermined ratio, and the blue color polarizing filter 8 is directly dyed C.I. I.
Direct Blue 202 and C.I. I. Direc
t Violet 51 is dyed and stretched using a dye solution containing a predetermined ratio, and the green color polarizing filter 10 is C.I. I. Direct Blue 202
And C. I. The dye is formed by stretching using a dyeing solution in which Direct Yellow 12 and Direct Yellow 12 are blended in a predetermined ratio, and each has an absorption axis transmittance characteristic as shown in FIG.

The behavior of the white light from the monochrome cathode ray tube 1 is determined by dividing the three primary colors of red, green and blue in one field period into three in a time series.
As a rotation, the light is polarized to cyan and red by a color polarizing filter 6 as a red color polarizing plate. Next, the liquid crystal cell 7 is turned on and off, no rotation is performed, and the liquid crystal cell 7 is selectively rotated by 90 °, so that a color polarizing filter 8 as a blue color polarizing plate is formed.
, Resulting in red and blue and cyan and black without transmitted light. In addition, these lights are selectively subjected again to the process of no rotation and 90-degree rotation in the liquid crystal cell 9 and pass through a color polarizing filter 10 as a green color polarizing plate. The transmitted light becomes blue, red, green, and cyan, and red, green, and blue can be separated.

As described above, the mixed phosphor on the phosphor screen 2 is
A blue light-emitting phosphor having a blue component having a wavelength of about 450 nm to 480 nm, and a wavelength of 520 nm to 5
An emission spectrum comprising a green light-emitting phosphor having a green component at about 50 nm and a red light-emitting phosphor having a red component at a wavelength of about 600 nm to 630 nm, and the intensity of other light-emitting components is extremely low. A color polarizing filter 6 having an absorption axis transmittance of 20% or less in a wavelength range of 550 nm or less;
A color polarizing filter 8 having a transmittance of 20% or less in an absorption axis in a wavelength range of 0 nm or more and 710 nm or less, and a color polarizing filter having a transmittance of 20% or less in a wavelength range of 480 nm or less and 600 nm or more. By using 10, the emission of the fluorescent screen 2 existing in the overlapping portion of the transmission spectrum among the color polarizing filters 6, 8, and 10 can be suppressed to an extremely low level. , Suppresses a decrease in color purity.

Further, since the activation amount of at least one of the blue light emitting phosphor thulium, the green light emitting phosphor holmium and erbium, and the red light emitting phosphor europium is too small or too large, the luminance decreases. Actually, the amount of the activator varies depending on the host, but for thulium, holmium and erbium, 0.01 to 3 atomic%.
In the case of europium, it is preferably in the range of 0.5 to 10 atomic%.

The base of the mixed phosphor on the phosphor screen 2 is a rare earth oxysulfide represented by the chemical formula of A ₂ O ₂ S, where A is at least one of the group of Y, La, Gd and Lu. In addition, there are various kinds such as zinc sulfide, yttrium oxide, yttrium silicate and lanthanum oxychloride.When rare earth oxysulfide is used as the base of blue, green and red component phosphors, the particle size and particle It is easy to obtain uniform mixed phosphors because
Image quality is improved.

Here, Examples 1 to 3 using blue light-emitting phosphors, green light-emitting phosphors and red light-emitting phosphors at the ratios shown in Table 1 formed based on the above-described embodiment,
Experimental results using Comparative Examples 1 to 3 will be described.

The phosphor on the phosphor screen 2 of the first embodiment includes La ₂ O activated with 0.5 atomic% thulium to the blue light emitting phosphor.
₂ S: Tm, La ₂ O ₂ S: Ho activated with 0.3 atomic% holmium on the green light emitting phosphor, 4 on the red light emitting phosphor.
A mixture of Y ₂ O ₂ S: Eu activated with atomic% europium in a weight ratio of 67: 30: 3 is used.

The phosphor on the phosphor screen 2 of the embodiment 2 includes La ₂ O activated with 0.5 atomic% thulium to the blue light emitting phosphor.
₂ S: Tm, La ₂ O ₂ S: Er activated with 0.3 at% erbium for green light emitting phosphor, 4 for red light emitting phosphor.
A mixture of Y ₂ O ₂ S: Eu activated with atomic% europium in a weight ratio of 73: 25: 4 is used.

The phosphor on the phosphor screen 2 of the embodiment 3 includes Gd ₂ O activated with 0.5 atomic% thulium to the blue light emitting phosphor.
₂ S: Tm, Gd ₂ O ₂ S: Ho activated with 0.3 atomic% holbium for the green light emitting phosphor, and 4 for the red light emitting phosphor.
A mixture of Gd ₂ O ₂ S: Eu activated with atomic% europium in a weight ratio of 77: 21: 2 is used.

As the phosphor on the phosphor screen of Comparative Example 1, a so-called P45 phosphor, a white light-emitting terbium-activated yttrium oxysulfide phosphor is used.

The phosphor on the phosphor screen of Comparative Example 2 was a so-called P22 phosphor, a blue light-emitting phosphor, and ZnS: Ag, C.
1, ZnS: Cu, Au, Al for the green light-emitting phosphor, and Y ₂ O ₂ S: Eu for the red light-emitting phosphor, each having a weight ratio of 3
What was mixed in the ratio of 5:30:35 is used.

The phosphor on the phosphor screen of Comparative Example 3 was ZnS: T obtained by activating a blue light-emitting phosphor with 0.5 at% thulium.
m, La ₂ O ₂ S: Tb activated with 5 at% terbium for the green light emitting phosphor, and Y ₂ O ₂ S: E for the red light emitting phosphor.
u are mixed at a weight ratio of 67:19:14.

The mixing ratio of the mixed phosphors used in Examples 1 to 3 and Comparative Examples 2 and 3 is such that the display color when white is displayed on a color image display device is CIE1931.
Adjustments were made so that both x and y were in the range of 0.32 to 0.33 when expressed in the standard color system.

[0033]

[Table 1] The emission spectrum of the mixed phosphor used in Example 1 was as shown in FIG. 3, and the emission spectrum of the mixed phosphor used in Example 2 was as shown in FIG.

In Examples 1 to 3, the monochrome cathode ray tube 1 of the embodiment was used, and in Comparative Examples 1 to 3, a sedimentation method using a white light-emitting terbium-activated yttrium oxysulfide phosphor as a P45 phosphor was used. A white light-emitting monochrome cathode ray tube having a phosphor screen formed thereon was used.

Then, in the color image display device, when the display color when each color was displayed was measured with a chromaticity meter, the results shown in Table 2 were obtained. Table 2
The display colors shown in () in the CIE1976 UCS chromaticity diagram
v ′) shows the measurement results displayed in the coordinate system.

[0036]

[Table 2] According to the experiment, as shown in Table 2, the display colors at the time of displaying red, green, and blue in Examples 1 to 3 have all shifted to higher color purities than Comparative Examples 1 to 3. Also, when comparing the area of a triangle surrounded by red, green, and blue when represented by (u ′, v ′) coordinates, that is, the size of the color reproduction area, when comparing with Comparative Example 1 as a reference, Although the area of the color gamut was relatively small at 114% in Example 2 and 97% in Comparative Example 3, it was greatly expanded to 131% in Example 1, 130% in Example 2, and 132% in Example 3. .

[0037]

According to the present invention, a blue light-emitting phosphor whose phosphor surface is activated by thulium, a green light-emitting phosphor activated by at least one of holmium and erbium, and europium are activated. Since the mixed phosphor of the red light-emitting phosphor has a small amount of light-emitting components existing in the overlapping portion of the transmission spectrum of the liquid crystal color shutter, the color mixture of the display colors of red, green and blue can be improved, and the color reproduction range can be expanded.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating a color display device according to an embodiment of the present invention.

FIG. 2 is a graph showing absorption axis transmittance characteristics of the respective color polarizing plates;

FIG. 3 is a graph showing an emission spectrum of the mixed phosphor used in Example 1 of the embodiment.

FIG. 4 is a graph showing an emission spectrum of the mixed phosphor used in Example 2 of the same.

[Explanation of symbols]

Reference Signs List 1 monochrome cathode ray tube 2 phosphor screen 3 liquid crystal color shutter 6,8,10 color polarizing filter as color polarizing plate

Continuation of the front page (72) Inventor Ryoji Tsuda 7-1 Nisshincho, Kawasaki-ku, Kawasaki-shi, Kanagawa F-term (reference) in Toshiba Electronic Engineering Co., Ltd. 2H091 FA09X FA09Z FA43Z FB06 FD06 FD24 LA03 LA15 MA07 5C060 AA07 BA04 BA07 BB13 DA00 JA00 5G435 AA04 BB02 BB12 CC12 FF05 HH06

Claims (4)

[Claims] 1. A mixture of a blue light emitting phosphor whose phosphor surface is activated by thulium, a green light emitting phosphor activated by at least one of holmium and erbium, and a red light emitting phosphor activated by europium. A color image display device comprising: a monochrome cathode ray tube having a phosphor and displaying an image; and a liquid crystal color shutter for separating an image displayed by the monochrome cathode ray tube into colors. 2. The liquid crystal color shutter has three color polarizers of blue, green and red, and two liquid crystal shutters located between the three color polarizers. The blue polarizer has a wavelength of 520 nm. 710 nm or less The green polarizing plate has a wavelength of 480 nm or less and a wavelength of 600 n.
2. The color image display device according to claim 1, wherein the transmittance of the absorption axis of the red polarizing plate is not more than 20% in each wavelength region of not more than 550 nm. 3. The color image display device according to claim 1, wherein each of the blue light emitting phosphor, the green light emitting phosphor, and the red light emitting phosphor is a rare earth oxysulfide phosphor. 4. A blue light emitting phosphor, a green light emitting phosphor and a red light emitting phosphor, wherein A is at least one of Y, La, Gd and Lu, and B is any one of Tm, Ho, Er and Eu. ,
4. The color image display device according to claim 3, wherein, when 0.0001 ≦ x ≦ 0.1, each of them is (A _1-x , B _x ) ₂ O ₂ S.