JPH0433239A - Cathode-ray tube - Google Patents

Abstract

PURPOSE:To easily form a fluorescent screen on which the light of phosphors can be efficiently extracted by adding vanadium pentaoxide to borophosphate glass to obtain low-softening point glass not deteriorated in a strong alkaline aqueous solution. CONSTITUTION:Phosphoric acid (85% H3PO4), boron oxide (B2O3), basic magnesium carbonate (MgCO3)4, cerium acetate (Ce(CH3COO)3.H2O), lithium carbonate (LiCO3), sodium hydrogencarbonate (NaHCO3), and vanadium pentaoxide (V2O5) are mixed. The mixture is put in a crucible, and it is gradually heated from the room temperature and baked to obtain the borophosphate glass made of P2O5 35-50mol%, B203 2-10mol%, MgO.CaO, BaO, CeO2, Li20, Na2O, and V2O5. A new meshy structure is formed between V2O5 and P2O5 in the glass, and the elution of ions into an alkaline aqueous solution can be prevented.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a cathode ray tube fluorescent surface, and particularly to a cathode ray tube having a bright fluorescent surface.

[Conventional technology]

The fluorescent surface of a conventional color cathode ray tube is formed as follows. A photoresist slurry containing a phosphor is applied to the inner surface of the face plate to form a coating film, and the coating film at the position where the phosphor is to be cured by exposure to ultraviolet light and developed to form the phosphor. Provide layers. In order to provide phosphor layers of three different luminescent colors, the same operation is repeated three times to form phosphor layers of each luminescent color. A metallized film of aluminum is then formed over the phosphor layer. Finally, organic matter is removed by panel baking. In the phosphor surface formed by this method, the phosphor layer and the faceplate are in contact only at small points;
are not in contact in most parts. Currently, as color cathode ray tubes become larger, it is desired to form a fluorescent surface for a bright screen. The bright cathode ray tube fluorescent surface described here is a fluorescent surface with a structure in which a phosphor layer coated on the inner surface of the face plate guides the excited luminescence generated by electron beam irradiation to the outer surface of the face plate without loss. It is about. In other words, it refers to a phosphor surface having a structure that allows the light of the phosphor that has been excited to emit light to be efficiently extracted to the front of the screen. As one way to achieve this goal, we previously proposed a phosphor surface with a shallow optical contact between the inner surface of the face plate and the phosphor coated there. In a fluorescent surface with such a structure, the emitted light has fewer reflective surfaces to pass through before exiting to the outer surface, and the reflectance is low because it passes through a layer with a higher refractive index than the vacuum layer. Become. Therefore, the emitted light can be efficiently extracted to the outside surface. The fluorescent surface having the above structure can be formed through the following process. (1) A suspension consisting of low softening point glass powder, barium acetate, and water glass is applied to the inner surface of the face plate,
A layer of low softening point glass powder is formed which settles together with the barium silicate produced in the suspension. (2) heating and melting the low softening point glass powder layer;
A face plate with a layer of fused low softening point glass on the inner surface is created. (3) On the inner surface of the face plate when it is in the state of (2),
A phosphor layer is formed in a conventional manner. (4) Heat and melt again to establish optical contact between the low softening point glass layer and the phosphor layer. In addition, as a prior art related to the present invention, Japanese Patent Application No. 1983-
No. 273141 can be mentioned.

[Problem to be solved by the invention]

However, since strongly alkaline water glass is used in the above process (1), there is a problem that the low softening point glass powder is hydrolyzed and deteriorated. Since the melting temperature of hydrolyzed low-softening glass is higher than that of the original glass, it cannot be sufficiently melted at conventional heating temperatures, and only a partly cloudy film with poor transparency can be formed. The purpose of the present invention is to provide a low softening point glass that does not deteriorate even in a strongly alkaline aqueous solution, and to provide a phosphor glass having a structure that allows the light of the excited phosphor to be efficiently extracted to the front of the screen. The object of the present invention is to make it possible to easily form a light surface.

[Means to solve the problem]

In order to achieve the above objective, we added vanadium pentoxide (V, 05) to the conventionally known borophosphate glass to improve its alkali resistance and have a low softening point that does not deteriorate even in strongly alkaline aqueous solutions. The glass was provided. The fact that water resistance is improved by the addition of vanadium pentoxide is that for phosphorus-lead glass (glass made of oxides of phosphorus, lead, alkali metals, and alkaline earth metals), Ray (
Glass Technology (N.H. Ray) et al.
Glass Technology)'), 14 (2
), 50-55 (1973). However, our provided boron phosphate glass (
Similar effects have not been reported for borophosphate glass (borophosphate glass). In particular, little is known about its properties against alkaline aqueous solutions. As a low softening point glass composition used in the present invention, P2
It is desirable to contain 35-50 mol% of O5 and 2-10 mol% of B2O2. If it is within this range, the softening point temperature will be around 400° C., so that only the low softening point glass layer can be melted in the heating process of the face plate of the cathode ray tube without changing the panel glass. Further, the amount of vanadium pentoxide added is preferably in the range of 0.2 to 3.5 mol%. This is because if the amount of vanadium pentoxide added is too small, the water resistance will be weak, whereas if it is too large, the softening point temperature will become high, which is unfavorable in terms of the process. [Function] According to the present invention, by adding vanadium pentoxide, a new network structure is formed between V2O5 and P2O inside the glass, which prevents the elution of ions into the alkaline aqueous solution. It has improved alkali resistance.

【Example】

Hereinafter, the present invention will be explained by examples. First, we will discuss the synthesis method of low softening point glass. The raw materials were weighed as shown below and mixed well in an agate mortar. Phosphoric acid (85% H3P04)...103.
76g boron oxide (B, O,)...
・3.66 g basic magnesium carbonate ((MgCO□
), ・Mg(OH) z ・5 H-0)
・=・・・8-74 g Calcium carbonate (Ca COa
) ...9.09 g barium carbonate (B
a COa) ...9.96 g Cerium acetate (Ce (CHa COO)a ・Hz O)・
...0.68 g Lithium carbonate (LiCO,) ...9.
44g Sodium hydrogen carbonate (NaHCO,) 21.34g Vanadium pentoxide (VX○,) 2.
After transferring 72 g of the mixed compound to a crucible, it was gradually heated from room temperature and fired in air at 800°C for 2 hours to produce 45P205/5B20.・9Mg0・9Ca
C15BaO・0.2CeO2・12.65L i, 0
・12.65Na20 ・1.5V, O, composition (
mol %) of borophosphate glass was obtained. The softening point of this glass was 416°C±5°C. This glass was crushed into powder in an agate mortar. Table 1 shows the composition and properties of the low softening point glass synthesized by this method. Examples that do not contain vanadium pentoxide are also shown in Table 1 as reference examples. In order to compare the water resistance of the synthesized glasses, they were powdered and immersed in an IN aqueous sodium hydroxide solution at 25° C., and the rate of hydrolysis with respect to the immersion time was measured. After being immersed for a certain period of time, it was taken out, washed repeatedly with water until the supernatant liquid showed neutrality, dried, and then melted on a glass substrate. The transmittance of the obtained glass film was measured and the results are shown in Table 2. This result shows that glass containing vanadium pentoxide hardly changes if the immersion time is within 4 hours. In contrast, in the glass of the reference example, hydrolysis progresses and some portions do not melt, and the sample after heating becomes cloudy, resulting in a decrease in transmittance. Table 2 Comparison of water resistance (relationship between alkali immersion time and transmittance) Next, an example in which a fluorescent surface was formed using the glass of the present invention will be described. The inner surface of a faceplate with a diagonal length of 6 inches was coated with 625 mΩ of ion-exchanged water and 40 m of 0.9% barium acetate.
Fill with mixture A. Add 225mm of ion exchange water to this.
, 0.04 g of glass powder of the invention, 11% water glass 4
0 mQ of suspension was injected. The glass powder was allowed to settle on the inner surface of the faceplate for 10 minutes. The supernatant was removed little by little, and the faceplate was air-dried. Next, it was heated for 1 hour in a furnace adjusted to 450°C. After cooling and washing with ion-exchanged water, a face plate with a thin layer of transparent low softening point glass was obtained. Then, a pigmented blue phosphor was applied to the inner surface in the same manner. then 4
It was heated at 50° C. for 1 hour to form an optical contact between the inner surface of the face plate and the phosphor via the low softening point glass. Furthermore, aluminum evaporation, frit baking, and electron gun mounting were performed to create a cathode ray tube. For comparison, a comparison area was formed in exactly the same manner except that the low softening point glass layer was not formed. When comparing the brightness of both cathode ray tubes,
The light with optical contacts was 10% brighter than the light without optical contacts.

【Effect of the invention】

Claims (1)

[Claims] 1. In a cathode ray tube having a fluorescent surface with optical contact between the inner surface of the face plate and the phosphor layer via a low softening point glass layer, 35-50 mol% of P_2O_5 is used as the low softening point glass composition. ,B_2O
Contains 2-10 mol% of _3, and as other components alkaline earth metals and alkali metal oxides and V_2
A cathode ray tube characterized by using borophosphate glass containing O_5.