JPH09217061A - Red color generating fluorescent material and cathode ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a fluorescent material having a sufficient color generation and a color pureness and also attaining a high brightness, and to provide a cathode ray tube having a bright image, also good in color balance and attaining a high quality picture image. SOLUTION: This red color generating fluorescent material is a fluorescent material basically expressed by Y2 O2 S:Eu or Y2 O2 S:Eu, RE (RE expresses at least one element selected from among Tb, Pr, Er and Sm), and this cathode ray tube is equipped with the red color generating fluorescent material of the above fluorescent material containing Cs and a coated membrane of fluorescent materials as a fluorescent surface. The cathode ray tube uses the red color generating fluorescent material among the above fluorescent materials, basically expressed by Y2 O2 S:Eu or Y2 O2 S:Eu, ER (RE expresses at least one kind of element selected from among Tb, Pr, Er and Sm) and containing Cs.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phosphor used in a cathode ray tube such as a color television or a computer display, and a cathode ray tube using this phosphor.

[0002]

2. Description of the Related Art In recent years, color televisions, computer displays, and the like have become higher in quality and higher in definition, and the cathode ray tubes used therein have become larger and higher in quality.

As is well known, a cathode ray tube used for a color television, a computer display and the like uses a phosphor (cathode luminescence) that emits an electron beam as a medium of excitation energy (cathode luminescence). In order to display almost all colors by combining the three primary colors (additive color mixture), blue, green, and red-emitting phosphors are used.

Of these, rare earth phosphors are mainly used as red-emitting phosphors, and europium-activated yttrium oxysulfide phosphor (Y ₂ O ₂ S: Eu), europium-activated yttrium oxide phosphor ( Y ₂ O ₃ : E
u), europium-activated yttrium vanadate phosphor (YVO ₄ : Eu), etc. are typical.

In order to improve the light emission characteristics, attempts have been made to introduce a trace amount of an element that can serve as a coactivator into these rare earth phosphors.

For example, Japanese Patent Publication No. 47-13243 discloses that
It has been proposed to add a small amount of Tb to improve the saturation characteristic of the luminance with respect to the current and improve the emission luminance. In addition, Japanese Patent Publication No. 47-13244 contains Mn,
Japanese Patent Application Laid-Open No. 63-101480 proposes to improve the emission brightness by adding a small amount of V. Further, Japanese Patent Publication No. 63-45719 proposes to improve the current characteristics by adding Er.
No. 36473, Y ₂ O ₂ S: Eu, Tb contains a trace amount of W.
It has been proposed to improve the voltage saturation characteristic of light emission luminance by adding.

Among these many attempts, rare earth oxysulfide phosphors are widely used in cathode ray tubes for color televisions, computer displays, etc., because the emission color is practically sufficiently red and the emission brightness is high. ing. Especially,
The cathode ray tube currently put into practical use is a europium-activated yttrium oxysulfide phosphor (Y ₂
O ₂ S: Eu, Tb) is commonly used because it exhibits relatively good light emission characteristics.

[0008]

However, particularly in high-definition televisions, high-definition computer displays, etc., the accelerating voltage of the electron beam that excites the phosphor on the phosphor screen is increased with the increase in size and quality of the cathode ray tube. On the other hand, although it is high, it is difficult to increase the excitation current density from the viewpoint of focus characteristics, so that the average excitation current density of the entire phosphor screen is low. Therefore, in a cathode ray tube such as a high-definition television or a high-definition computer display, it is difficult to obtain sufficient emission brightness with the conventional Y ₂ O ₂ S: Eu, Tb type phosphor. There is.

Further, in the conventional cathode ray tube using the phosphor, since the emission brightness of the phosphor is not sufficient, the brightness and color balance of the screen are deteriorated, and it is difficult to obtain a high quality screen. There was a problem.

The present invention has been made in order to solve the above-mentioned problems, and it is a phosphor having sufficient emission color and color purity and achieving high brightness, and a bright screen and a good color balance. An object of the present invention is to provide a cathode ray tube that achieves a high quality screen.

[0011]

Means for Solving the Problems In order to achieve the above object, the present inventors have developed a europium-activated yttrium oxysulfide phosphor (Y ₂ O ₂ S: Eu, Y ₂ O ₂ S: Eu, Tb).
Based on the above, various experiments were conducted to obtain a phosphor having sufficient emission color and color purity and high brightness, and the present invention was achieved.

That is, the red light emitting phosphor according to the present invention is characterized in that the phosphor is basically represented by Y ₂ O ₂ S: Eu, and the phosphor contains Cs.

Another red-emitting phosphor according to the present invention is Y ₂ O ₂ S: Eu, RE (where RE is Tb, P
A phosphor basically represented by (indicating at least one element selected from r, Er, and Sm) is characterized in that the phosphor contains Cs.

The cathode ray tube according to the present invention is a cathode ray tube having a phosphor coating as a phosphor screen, wherein the red-emitting phosphor among the phosphors is basically Y ₂ O ₂ S: Eu. It is a phosphor that is represented and contains Cs.

Another cathode ray tube according to the present invention is a cathode ray tube having a phosphor coating as a phosphor screen, wherein the red-emitting phosphor among the phosphors is Y ₂ O ₂ S: Eu,
The phosphor is basically represented by RE (wherein RE represents at least one element selected from Tb, Pr, Er and Sm) and is a phosphor containing Cs.

The red-emitting phosphor according to the present invention is Y ₂ O ₂
S: Eu phosphor added with Cs or Cs and RE element as a co-activator. Where Eu is
It is preferably contained in the range of 3.0 to 8.0% by weight with respect to the phosphor base (Y ₂ O ₂ S). If the Eu content is less than 3.0% by weight, the emission color will be pink or orange, and the characteristics as a red emission component will deteriorate, while if it exceeds 8.0% by weight, the emission brightness will decrease. I will leave. Practically, the Eu content is 5.0 to 6.
It is more preferable to set it in the range of 0% by weight.

Cs is a component effective in improving the emission luminance characteristic, and is a characteristic component in the present invention. In the phosphor of the present invention, as described in detail below, Cs is added in the range of 5 × 10 ^{−4 to} 5 × 10 ⁻² wt% with respect to the basic phosphor composition (Y ₂ O ₂ S, Eu). It is important to include in.

Further, in the phosphor of the present invention, the RE element (at least one element selected from Tb, Pr, Er and Sm) is co-attached to Y ₂ O ₂ S which is a phosphor base together with Eu and Cs. By activating, it is possible to improve the emission color and the emission luminance characteristic.

When the RE element is used as a coactivator, R
When at least one element selected from Tb, Pr and Er is used as the E element, the RE element is added to the basic phosphor composition (Y ₂ O ₂ S, Eu) at 5 × 10 ^{−4 to} 5 −5.
It is preferably contained in the range of ^{x10 -3} % by weight. T
If the content of at least one element selected from b, Pr and Er is less than 5 × 10 ⁻⁴ wt%, the effect of improving the emission luminance characteristic cannot be sufficiently obtained, and conversely 5 × 10 4
^If it exceeds ^-3 % by weight, the emission luminance tends to decrease.

When Sm is selected as one of the RE elements, the RE element has a basic phosphor composition (Y ₂ O).
₂ S, Eu) in an amount of 5 × 10 ^{−4 to} 0.5% by weight. The reason for defining this content is similar to the above reason, but in this case, since Sm further has an effect of substituting for Eu, the RE element is added as compared with the case where only Tb, Pr and Er are selected as the RE element. It can be contained in a large amount. Therefore, in this case, the content of Eu can be reduced.

Furthermore, when Tb is particularly selected as the RE element, the linearity of the emission luminance with respect to the excitation current density is maintained and the saturation of the emission luminance is suppressed, which is preferable.

Further, a mixed system of Tb and Sm as the RE element is also preferably used. Since Sm has an effect of substituting for Eu, the RE element can be contained in a larger amount than in the case where only Tb is selected, whereby the content of Eu can be reduced. The content of the RE element in this case is based on the range of 5 × 10 ^{−4 to} 5 × 10 ⁻³ % by weight, which is the above-mentioned Tb amount, as a basic phosphor composition (Y ₂ O ₂
Sm can be contained up to the range of 0.5% by weight with respect to S, Eu).

Next, the content of Cs will be described. FIG.
Is the relationship between the Cs content and the emission brightness in the Y ₂ O ₂ S: Eu, Tb, Cs phosphor (the Eu and Tb contents are 6.8 and 1 × 10 ⁻³ wt%, respectively). It is the figure shown.

The emission brightness was measured by irradiating a cathode ray tube finished with the above phosphor with an electron beam (excitation voltage 25 kV, excitation current 200 μA) to excite the phosphor in a window pattern. In addition, in FIG. 1, the vertical axis represents the relative light emission luminance (value when the phosphor not containing Cs is 100), and the horizontal pongee (logarithmic scale) represents the Cs content.

As shown in FIG. 1, the Cs content is 5 × 1.
If it is less than 0 ^-4 % by weight, the effect of improving the emission luminance characteristic cannot be sufficiently obtained, and conversely, if it exceeds ^{5x10 -2} % by weight,
The decrease in light emission brightness becomes large. The more preferable content of Cs is in the range of 1 × 10 ⁻³ to 1 × 10 ⁻² wt%.

Further, in order to improve the contrast of an image, a fluorescent substance may be coated with a filter substance and used. However, even if the fluorescent substance of the present invention is coated with the filter substance, the superiority of the brightness characteristic is changed. Not a good one.

The cathode ray tube of the present invention uses the above-described phosphor of the present invention as at least a red light emitting component.

Therefore, in the cathode ray tube of the present invention, the screen is bright and the color balance is good, so that a high quality screen is achieved.

[0029]

Embodiments of the present invention will be described below.

First, an outline of steps for producing the phosphor of the present invention will be described.

The following (1) to (1) containing elements constituting the phosphor
(3) Or each raw material of (1) to (4) (1) Yttrium oxide (Y ₂ O ₃ ) or yttrium compound such as hydroxide (2) Europium oxide (Eu ₂ O ₃ ) or carbonic acid Europium compounds such as salts (3) cesium compounds such as Cs ₂ CO ₃ and CsI (4) at least one rare earth compound selected from oxides of RE elements (eg, Tb ₄ O ₇ ) or carbonates in appropriate amounts After weighing, mix thoroughly.

Then, after drying the obtained mixture, S is added as a reducing agent, and if necessary, sodium carbonate (Na ₂ CO ₃ ) or potassium phosphate (K) is used as a fluxing agent.
₃ PO ₄ ) etc. are added and the whole is mixed uniformly.

Then, the mixture is filled in a firing container such as a quartz tube or an alumina crucible, and the lid is closed.
Baking is performed at a temperature of 00 to 1300 ° C.

Finally, the obtained fired product is subjected to general treatment steps such as milling, washing, drying and sieving to obtain the phosphor of the present invention.

The amount of Cs is about 1/10 of the amount charged in the raw material mixture, and the content in the phosphor changes depending on the amount charged in the raw material mixture. It is preferable to set the charging amount for the raw material mixture.

FIG. 2 shows the structure of a cathode ray tube which is an embodiment of the present invention.

In FIG. 2, the cathode ray tube has an envelope composed of a panel 1 and a funnel 2 integrally joined to the panel 1, and the inner surface of the panel 1 has three colors of light emitting blue, green and red. A phosphor screen 3 including a phosphor layer and a black light absorbing layer filling the gaps of the three-color phosphor layer is formed.
The red light emitting phosphor of the present invention as described above is used for the phosphor layer that emits red light among the three color phosphor layers. Such a phosphor layer is formed by adding a phosphor to PV.
It can be obtained by using a slurry prepared by dispersing A, a surfactant, pure water and the like, and applying this to the inner surface of the panel according to a usual method to form a fluorescent screen.

The three-color phosphor layer may have a stripe shape or a dot shape, but here, it has a dot shape. A shadow mask 4 having a large number of electron beam passage holes formed therein is mounted so as to face the fluorescent screen 3.

An electron gun 7 for irradiating the fluorescent screen 3 with electron beams 6B, 6G and 6R is disposed inside the neck 5 of the funnel 2, and the electron beam emitted by the electron gun 7 is provided. 6B, 6G and 6R collide with the phosphor screen 3 to excite and emit light of the three-color phosphor layer. In addition, 8 is a supporting means for supporting the shadow mask 4,
Reference numeral 9 is an anode terminal provided on the side wall of the funnel 2, and 10 is an internal thin film formed on the inner surface of the funnel 2.

The cathode ray tube according to the above embodiment is an example in which the present invention is applied to a color cathode ray tube. At this time,
The remaining phosphors that emit two colors are arbitrarily selected.

The green light emitting phosphor and the blue light emitting phosphor are not limited in any way, but the green light emitting phosphor having zinc sulfide as a base material and copper as an activator and the zinc light emitting material having zinc sulfide as a base material and silver It is more preferable to use a blue light emitting phosphor as an activator because the overall light emission characteristics are balanced.

In the above embodiment, the case where the present invention is applied to the color cathode ray tube has been described as an example.
It goes without saying that the phosphor and the cathode ray tube of the present invention can be used as a monochromatic cathode ray tube.

[0043]

Embodiments of the present invention will be described below.

Example 1 First, as shown below, the phosphor raw materials were weighed.

Y ₂ O ₃ : 93.2 g Eu ₂ O ₃ : 6.8 g Tb ₄ O ₇ : 1 × 10 ⁻³ g CsCO ₃ : 0.1 g Na ₂ CO ₃ : 40 g S: 40 g K ₃ PO ₄ : Then, these raw materials were mixed sufficiently well to obtain a raw material mixture for the phosphor.

Then, this mixture was filled in an alumina crucible, covered with a lid, and then fired at 1500 ° C. for 2 hours.

Next, this calcined product was washed to remove miscellaneous ions, and then bead milling was performed to disperse the mixture. Finally, coat the surface with fine particulate silica,
After washing, drying and sieving the phosphor of the present invention: Y ₂ O ₂
S: Eu, Tb, Cs were obtained. On the other hand, as a control, a phosphor of the comparative example: Y ₂ O ₂ S: Eu, Tb was obtained under completely the same conditions except that CsCO ₃ was not added to the above raw material.

Subsequently, ammonium dichromate, which is a chromic acid compound, and polyvinyl alcohol are added to these phosphors to prepare a photosensitive slurry, and the photosensitive slurry is applied to the inner surface of the panel for a cathode ray tube by a usual spin coating method. The coating was applied to form a fluorescent film, and the cathode ray tube shown in FIG. 2 was formed. In this example, Zn was used as the green phosphor.
S: Cu, Al, and ZnS: Ag as a blue phosphor.
Is used.

Then, the emission brightness was measured using this cathode ray tube.

(Example 2) As shown below, after weighing each of the phosphor raw materials, the phosphor of the present invention: Y ₂ O ₂ S: Eu was prepared in the same manner as in (Example 1). , Tb,
Cs was obtained.

Y ₂ O ₃ : 93.2 g Eu ₂ O ₃ : 6.8 g Tb ₄ O ₇ : 2 × 10 ⁻³ g CsCO ₃ : 0.02 g Na ₂ CO ₃ : 40 g S: 40 g K ₃ PO ₄ : On the other hand, as a control, the phosphor of the comparative example: Y ₂ O was prepared under the same conditions except that CsCO ₃ was not added to the above raw material.
₂ S: Eu, Tb was obtained.

Then, a cathode ray tube was constructed in exactly the same manner as in Example 1 and the emission luminance was measured. (Example 3) As shown below, after weighing each of the phosphor raw materials, the phosphor of the present invention: Y ₂ O ₂ S: Eu, Tb, was used in the same manner as in (Example 1). Cs was obtained.

Y ₂ O ₃ : 93.2 g Eu ₂ O ₃ : 6.8 g Tb ₄ O ₇ : 1 × 10 ⁻³ g CsCO ₃ : 1 g Na ₂ CO ₃ : 40 g S: 40 g K ₃ PO ₄ : 10 g As a control, the phosphor of the comparative example: Y ₂ O under exactly the same conditions except that CsCO ₃ was not added to the above raw material.
₂ S: Eu, Tb was obtained.

Then, a cathode ray tube was constructed in exactly the same manner as in Example 1 and the emission luminance was measured. (Example 4) As shown below, after weighing each of the phosphor raw materials, the phosphor of the present invention: Y ₂ O ₂ S: Eu, Tb, was used in the same manner as in (Example 1). Cs was obtained.

Y ₂ O ₃ : 93.2 g Eu ₂ O ₃ : 6.8 g Tb ₄ O ₇ : 3 × 10 ⁻³ g CsCO ₃ : 0.25 g Na ₂ CO ₃ : 40 g S: 40 g K ₃ PO ₄ : On the other hand, as a control, the phosphor of the comparative example: Y ₂ O was prepared under the same conditions except that CsCO ₃ was not added to the above raw material.
₂ S: Eu, Tb was obtained.

Then, a cathode ray tube was constructed in exactly the same manner as in Example 1 and the emission luminance was measured. (Example 5) As shown below, after weighing each of the phosphor raw materials, the phosphor of the present invention: Y ₂ O ₂ S: Eu, Tb, was used in the same manner as in (Example 1). Cs was obtained.

Y ₂ O ₃ : 95.3 g Eu ₂ O ₃ : 4.7 g Tb ₄ O ₇ : 1 × 10 ⁻³ g CsCO ₃ : 0.07 g Na ₂ CO ₃ : 40 g S: 40 g K ₃ PO ₄ : On the other hand, as a control, the phosphor of the comparative example: Y ₂ O was prepared under the same conditions except that CsCO ₃ was not added to the above raw material.
₂ S: Eu, Tb was obtained.

Then, a cathode ray tube was constructed in exactly the same manner as in Example 1 and the emission luminance was measured. (Example 6) As shown below, after weighing each of the phosphor raw materials, the phosphor of the present invention: Y ₂ O ₂ S: Eu, Pr, was used in the same manner as in (Example 1). Cs was obtained.

Y ₂ O ₃ : 95.3 g Eu ₂ O ₃ : 4.7 g Pr ₆ O ₁₁ : 2 × 10 ⁻³ g CsI: 0.3 g Na ₂ CO ₃ : 40 g S: 40 g K ₃ PO ₄ : 10 g On the other hand, as a control, the phosphor of the comparative example: Y ₂ O ₂ S: E was prepared under the same conditions except that CsI was not added to the above raw material.
u and Pr were obtained.

Then, a cathode ray tube was constructed in exactly the same manner as in Example 1 and the emission luminance was measured. (Example 7) As shown below, after weighing each of the phosphor raw materials, the phosphor of the present invention: Y ₂ O ₂ S: Eu, Tb, Sm was used in the same manner as in (Example 1). , Cs were obtained. _{Y 2 O 3: 95.3g Eu 2} O 3: 4.4g Tb 4 O 7: 1 × 10 -3 g Sm 2 O 3: 0.3g CsCO 3: 0.5g Na 2 CO 3: 40g S: 40g K ₃ PO ₄ : 10 g On the other hand, as a control, the phosphor of the comparative example: Y ₂ O was prepared under the same conditions except that CsCO ₃ was not added to the above raw material.
₂ S: Eu, Sm were obtained.

Then, a cathode ray tube was constructed in exactly the same manner as in Example 1 and the emission luminance was measured. (Example 8) As shown below, after weighing each of the phosphor raw materials, the phosphor of the present invention: Y ₂ O ₂ S: Eu, Cs was prepared in the same manner as in (Example 1). Obtained.

[0062] _{Y 2 O 3: 95.3g Eu 2} O 3: 4.7g CsCO 3: 0.25g Na 2 CO 3: 40g S: 40g K 3 PO 4: 10g On the other hand, as a control, CsCO ₃ in the starting material Under the same conditions, except that no phosphor is added, the phosphor of the comparative example: Y ₂ O
₂ S: Eu was obtained.

Then, a cathode ray tube was constructed in exactly the same manner as in Example 1 and the emission luminance was measured. Here, Examples 1 to 1
Table 1 shows the relative values (relative brightness) of the emission brightness of the phosphor of the present invention measured in Example 8.

[0064]

[Table 1] The emission brightness is measured by irradiating the phosphor screen 3 with an electron beam 6R for red emission (excitation voltage 25 kV, excitation current 200 μA) and exciting each phosphor of Examples 1 to 7 in a window pattern. did. In Table 1, the relative brightness of the phosphor of the present invention in each example is a relative value when the emission brightness of the phosphor of the comparative example in each example is 100.

As is clear from Table 1, the phosphor of the present invention has higher emission brightness than the phosphor of the comparative example not containing Cs, and the improvement of emission brightness is achieved. It can be understood.

Further, the phosphor of the present invention was comparable to the phosphors of Comparative Examples in terms of emission color and color purity.

Further, from the above, since the cathode ray tube of the present invention has higher emission brightness than the conventional cathode ray tube, the screen is bright and the color balance is good.
A high-quality screen was achieved.

When the phosphor of Example 1 and the phosphor of Example 8 were compared, it was confirmed that the phosphor of Example 1 had higher emission brightness and was more practical.

[0069]

As described above, according to the present invention, the europium-activated yttrium oxysulfide phosphor (Y ₂
O ₂ S: Eu or Y ₂ O ₂ S: Eu, RE) containing Cs, to provide a red-emitting phosphor having sufficient emission color and color purity and high brightness. You can

Further, as the red light emitting phosphor, the above phosphor having sufficient emission color and color purity and achieving high brightness is used, so that the screen is bright and the color balance is good and the image quality is high. A cathode ray tube can be provided.

Therefore, the present invention is practically effective for various devices such as high-definition televisions and high-definition displays which are particularly required to have high brightness.

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between the Cs content in a Y ₂ O ₂ S: Eu, Tb, Cs phosphor and the emission luminance.

FIG. 2 is a diagram showing a configuration of a cathode ray tube which is an embodiment of the present invention.

[Explanation of symbols]

1 ... Panel 2 ... Funnel 3 ... Phosphor screen 4 ...
... Shadow mask 5 ... Neck 6B, 6G, 6R ... Electron beam 7 ...
… Electron gun 8 …… Supporting means 9 …… Anode terminal 10 …… Internal thin film

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kinno Funayama 72 Horikawa-cho, Sachi-ku, Kawasaki-shi, Kanagawa Higashi-Shiba Horikawa-cho Plant (72) Inventor Hiroyasu Yashima 7 Nisshin-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa 1 In Toshiba Electronics Engineering Co., Ltd. (72) Inventor Masanori Otake, 7 Nisshin-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa 1 In Toshiba Electronics Engineering Co., Ltd.

Claims (8)

[Claims] 1. A red-light-emitting phosphor, which is a phosphor basically represented by Y ₂ O ₂ S: Eu, wherein the phosphor contains Cs. 2. The Cs is 5 × 10 ⁻⁴ relative to the phosphor.
The red-emitting phosphor according to claim 1, characterized in that it is contained in the range of 5 × 10 ^-2 % by weight. 3. Y ₂ O ₂ S: Eu, RE (wherein RE is at least 1 selected from Tb, Pr, Er and Sm).
(Indicating the elements of the species)
A red light emitting phosphor, wherein the phosphor contains Cs. 4. The Cs is 5 × 10 ⁻⁴ relative to the phosphor.
The red-emitting phosphor according to claim 3, characterized in that the content of the red-emitting phosphor is in the range of 5 × 10 ^-2 % by weight. 5. The red-emitting phosphor according to claim 3, wherein the RE element is Tb. 6. The red-emitting phosphor according to claim 3, wherein the RE element is a mixed system of Tb and Sm. 7. A cathode ray tube having a phosphor coating as a phosphor screen, wherein the red-emitting phosphor among the phosphors is Y ₂ O ₂ S: Eu.
And a Cs-containing phosphor. 8. A cathode ray tube having a phosphor coating as a phosphor screen, wherein the red-emitting phosphor among the phosphors is Y ₂ O ₂ S: E.
u, RE (where RE is Tb, Pr, Er and Sm
A cathode ray tube, which is a phosphor basically represented by (indicating at least one element selected from) and containing Cs.