JPH10121041A - Image display tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an image display tube which has a phosphor film contg. a blue phosphor having a good color purity and γ-characteristics by using a phosphor contg. an alkaline earth metal, if necessary an alkali metal or Ag, Zr, or Hf, and oxygen. SOLUTION: A phosphor used comprises an element selected from among Ca, Sr, and Ba; is necessary an element selected from among Li, Na, K, and Ag; Zr and/or Hf; and oxygen and, more specifically, has a compsn. pref. represented by the formula: (A1-x Tmx )By Mz O3 (wherein A is Ca, Sr, or Ba; B is Li, Na, K, or Ag; M is Zr or Hf; 0.00001<=z<=0.7; 0<=y<=0.7; and 0.5<=z<=1.5). The phosphor provides a good blue color and a color purity unobtainable until now, and such characteristics can be further enhanced by using a Tm-derived blue component with a good color purity by an optical means such as a band filter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image display tube using a thulium-activated perovskite-type oxide phosphor that emits blue light when excited by electron beams, X-rays, ultraviolet rays, or the like.

[0002]

2. Description of the Related Art As televisions have become larger, projection televisions have begun to spread. CRTs used in projection televisions require high brightness in order to perform enlarged projection, and operate under a higher current density than ordinary CRTs for television. Therefore, a phosphor used for a projection television CRT generally needs to have good current-luminance characteristics (γ characteristics), not deteriorate with long-time excitation, and have good temperature characteristics.

[0003] As a phosphor currently used in a cathode-ray tube for a projection type television, red is Y ₂ O ₃ :
Eu ³⁺ , green as Y ₃ (Al, Ga) ₅ O ₁₂ : T
b ³⁺ , InBO ₃ : Tb ³⁺ , Y ₃ Al ₅ O ₁₂ : Tb ³⁺ ,
Y ₂ SiO ₅ : Tb ³⁺ , LaOCl: Tb ^3+, etc.
ZnS: Ag, Al is used as blue. However, among them, ZnS: Ag, Al, which is only practically used as a blue light emitting phosphor, has a γ characteristic in a high current density region, that is, an output with respect to an input current, which is higher than that of other color phosphors. As the current increases, the characteristic simply deviates from a straight line that increases in proportion to the undesired characteristics.Therefore, the focus of the electron beam spot is defocused, the actual current density is reduced, and the gamma characteristic is adjusted to red or green. It is the present situation.

[0004]

In recent years, the definition of a cathode ray tube has been advanced, and it has conventionally been necessary to narrow the spot of an electron beam for each color. That is, it is necessary to increase the current density on the phosphor film surface of the cathode ray tube. Therefore, a phosphor having a good γ characteristic is desired particularly in a blue color. The present invention has been made to solve the above problems. An object of the present invention is to provide a video display tube in which a phosphor film contains a blue phosphor having improved γ characteristics by developing a novel perovskite oxide phosphor activated with thulium.

[0005]

The gist of the present invention is that (a)
At least one element selected from the group consisting of Ca, Sr, and Ba; (b) if necessary, Li, Na,
An image display tube characterized in that the fluorescent film contains at least one element selected from the group consisting of K and Ag, (c) a phosphor composed of Zr and / or Hf, and (d) oxygen. .

BEST MODE FOR CARRYING OUT THE INVENTION

[0006] phosphor used in the present invention is specifically represented by the general formula _{(A 1-x Tm x)} B y M z O 3, A is C
at least one of a, Sr and Ba, B is Li,
M represents at least one element of Na, K and Ag, and M represents at least one element of Zr and Hf;
y and z are 0.00001 ≦ x ≦ 0.7, 0 ≦ y ≦
The phosphor preferably satisfies the range of 0.7, 0.5 ≦ z ≦ 1.5.

In the present invention, the above-mentioned phosphor can be used by mixing with other existing phosphors, for example, ZnS: Ag, Al or the like. Particularly excellent properties are recognized when the content of the other phosphor is less than half of the whole. One of the advantages of the present invention is to provide a blue color having good color purity, which has not been obtained so far, and to use a blue component having good color purity derived from Tm by using an optical means such as a band filter. Thereby, this characteristic can be further increased. For example, this can be realized by using a filter that transmits a pure blue color near 450 nm derived from Tm and cuts a component having a longer wavelength. It is particularly effective when used in combination with existing phosphors having poor color purity. The phosphor used in the present invention can be synthesized as follows. (1) Alkaline earth metals (Ca, Sr, Ba) are alkaline earth metal oxides such as oxides, hydroxides, carbonates, nitrates, etc. (2) Thulium oxide, thulium oxalate, carbonate Thulium compounds such as thulium (3) Alkali metals (Na, K, Li) are alkali metal oxides or alkali metal chlorides such as oxides, hydroxides, carbonates, and nitrates (4) Silver oxide, silver chloride, Silver compounds such as silver nitrate (5) Hafnium oxide and zirconium oxide are weighed in predetermined amounts according to the molar ratio of the phosphor to be obtained, and the raw material mixture is sufficiently mixed.

This mixture is fired, pulverized, washed with water and dried in the usual manner to obtain the phosphor used in the present invention. As an example, it is filled in a heat-resistant container such as a crucible and fired once or more in air or an oxidizing atmosphere at 800 to 1600 ° C. for 1 to 12 hours. If this fired product is pulverized, washed with water, dried and sieved, a blue-emitting perovskite-type oxide phosphor used in the present invention can be obtained.

[0009]

FIG. 1 shows a linear emission spectrum specific to Tm ³⁺ ions under electron beam excitation (Sr _0.99 Tm _0.01 ) Na _0.01 Hf.
O ₃ phosphor is shown as a representative example. The other phosphors of the present invention also showed almost the same emission spectrum. FIG. 2 shows the emission spectrum of the current ZnS: Ag, Al for comparison. FIG. 3 shows a powder X-ray diffraction diagram confirming the crystal structure of the phosphor.

FIG. 4 shows curve (b) of (Sr _0.99 Tm _0.01 ) Na
The γ characteristics of the _0.01 HfO ₃ phosphor under electron beam excitation were shown. Further, FIG. 4 curve a shows the γ of ZnS: Ag,
The characteristics were shown. However, in order to eliminate the difference in temperature rise, the measurement was performed while controlling the phosphor surface temperature to 100 ° C. or less. From FIG. 1, FIG. 2, and FIG. 4, this phosphor exhibits linear emission with better color purity (smaller chromaticity coordinate y value) than ZnS: Ag, Al, and has good γ characteristics. I understand.

[0011] In general formula _{(A 1-x Tm x)} B y M z O
_{In the} above-described phosphor represented by ₃ , the preferable content of Tm is 0.00001 ≦ x ≦ 0.7, more preferably, x is 0.001 ≦ x ≦ 0.1, and Preferably, 0.001 ≦ x ≦ 0.05. When x is too large, concentration quenching tends to occur, and when x is too small, light emission is also weak. On the other hand, the content of B is preferably 0 ≦ y ≦ 0.7. If the content is too large, impurities are increased and light emission is deteriorated, and B is preferably contained for the purpose of charge compensation. The range of 001 ≦ y ≦ 0.1 is particularly preferred. More preferably, 0.001 ≦ y ≦ 0.05. M
Is usually 1, but may be in the range of 0.5 ≦ z ≦ 1.5.

[0012]

Embodiments of the present invention will be described below. Example 1

Table 1 SrCO ₃ : 2.0227 g Tm ₂ O ₃ : 0.0270 g Na ₂ CO ₃ : 0.0074 g HfO ₂ : 2.9429 g

[0013] The above raw materials are mixed in a wet manner using ethanol.
After drying, filling in an alumina crucible,
At 1600 ° C. for 2 hours. Obtained fired product
Was crushed, washed with water, dried and sieved to obtain a phosphor. This fluorescence
The body composition is (Sr_0.99Tm _0.01) Na_0.01HfO_Threeso
Emission spectrum and diagram shown in Fig. 1 under electron beam excitation
4 showed the γ characteristic shown by the curve b. Also, this phosphor
The chromaticity coordinate values are x = 0.152 and y = 0.047.
Yes, chromaticity coordinate value x of ZnS: Ag, Al = 0.141
And y = 0.071, the y value is smaller and the color purity is better.
It turned out. As can be seen from FIG. 1 and FIG.
The phosphor used in the present invention has a narrow emission half width, so
If the light body is used for projection television,
Chromatic aberration of scanning lines projected on the screen is small and image resolution
Is improved. Example 2 The phosphor of Example 1 emitted light when excited by a 147 nm light source.
The chromaticity coordinate values shown at time are x = 0.163, y = 0.0
Barium aluminum which is usually used for PDP
Chromaticity coordinate value x = 0.14 of the magnesium oxide
4. Smaller y value and better color purity than y = 0.074
I understood that. Example 3 (Ca_0.95Tm_0.5) Na_0.5HfO_ThreeWhen using
The chromaticity coordinate values indicate x = 0.170 and y = 0.080,
Good color purity.

[0014]

According to the present invention, it is possible to obtain an image display tube containing a blue phosphor having good color purity and good γ characteristics in a fluorescent film, and to display an image for a cathode ray tube, a projection tube, a PDP or the like. Useful for tubes.

[Brief description of the drawings]

FIG. 1 shows the (Sr _0.99 Tm _0.01 ) Na _0.01 HfO of the present invention.
FIG. 4 is an electron-beam-excitation emission spectrum diagram of _three phosphors.

FIG. 2 is an electron-beam-excited emission spectrum of a known ZnS: Ag, Al phosphor.

FIG. 3 shows the (Sr _0.99 Tm _0.01 ) Na _0.01 HfO of the present invention.
₃ is a powder X-ray diffraction diagram confirming the crystal structure of the phosphor.

FIG. 4 is a diagram showing a relationship between an electron beam current density and a light emission intensity of a phosphor.

[Description of Signs] a Conventional ZnS: Ag, Al phosphor b (Sr _0.99 Tm _0.01 ) Na _0.01 HfO _{3 of the} present invention
Phosphor

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasuo Shimomura 1000 Kamoshita-cho, Aoba-ku, Yokohama-shi, Kanagawa Prefecture Inside the Mitsubishi Research Institute, Ltd. (72) Inventor: Shinichiro Nakamura 1000, Kamoshida-cho, Aoba-ku, Yokohama-shi, Kanagawa-ken, Yokohama Chemical Research Laboratory

Claims (8)

[Claims] 1. (a) at least one element selected from the group consisting of Ca, Sr, and Ba; (b) at least one element selected from the group consisting of Li, Na, K, and Ag if necessary An image display tube characterized in that the phosphor film contains a phosphor composed of the element (c), Zr and / or Hf, and (d) oxygen. 2. A phosphor general formula _{(A 1-x Tm x)} B y M
_z O ₃ (where A represents at least one element selected from the group consisting of Ca, Sr, and Ba, and B represents L
i represents at least one element selected from the group consisting of Na, K, and Ag, and M represents Zr and / or H
represents f, x represents a real number of 0.00001 ≦ x ≦ 0.7, y represents a real number of 0 ≦ y ≦ 0.7, and z represents 0.5 ≦ z
The video display tube according to claim 1, wherein the video display tube has a composition represented by the following formula: 3. The video display tube according to claim 2, wherein x is a real number satisfying 0.001 ≦ x ≦ 0.1. 4. The video display tube according to claim 3, wherein x is a real number satisfying 0.001 ≦ x ≦ 0.05. 5. The video display tube according to claim 2, wherein y is a real number satisfying 0.001 ≦ y ≦ 0.1. 6. The video display tube according to claim 5, wherein y is a real number satisfying 0.001 ≦ y ≦ 0.05. 7. The video display tube according to claim 1, wherein the fluorescent film further contains a ZnS: Ag, Al phosphor. 8. The video display tube according to claim 1, wherein a blue component having a high color purity derived from Tm is extracted and used by optical means.