MXPA97009047A - Phosphorus screen for a catodic rays tube without flashing and procedure for its manufacture - Google Patents

Abstract

The present invention relates to a method for manufacturing a phosphor screen for a non-flicker cathode ray tube, comprising the steps of forming red and green phosphor layers on a panel for a cathode ray tube on which a matrix, form a layer of blue phosphorus on the panel on which the black matrix was formed covering the blue phosphorous slurry and drying and forming a double layer of phosphorus coating with a slurry of ultraviolet phosphorus on the blue and dry phosphorus layer

Description

DISPLAY DB POSPORO FOR OH CATOMODIC RAYS TUBE WITHOUT BLINKING AND PROCEDIMIETO FOR ITS MANUFACTURE DESCRIPTION OF THE INVENTION The present invention relates to a phosphor screen for a cathode ray tube (hereinafter referred to as TRC), and particularly to a phosphor screen for a CRT, without flicker where the flicker phenomena are detected. They reduce by forming a double screen of phosphorus with ultraviolet phosphorus (hereinafter referred to as UV, on the conventional blue phosphor screen layer, and a process to prepare it.) A conventional TRC shadow mask uses three electron jets deflected by a coil, the jets pass through a perforated metal mask (mask-shade), before hitting a material selected on the phosphor screen.The selected phosphor formed on the inner surface of the screen comprises a set or template of fosioios? jo, vj Je and blue and a black matrix, (hereinafter referred to as BM), which is formed between the phosphors, the three chorr The electrons that pass through the shadow mask converge on the screen and each jet collides with a match between the red, green and blue phosphors. Generally a process for forming a phosphor screen comprises the following steps.

A photo base is covered over the inner surface of a panel dried by heat or other aediums, and exposed to ultraviolet rays irradiated through the recesses of the mask. The exposed panel is washed and developed to remove the resistant to the unexposed photograph and then dried. A black matrix material is coated on the panel, on which the coated portion is resistant to the photograph is traced regularly, subsequently, the panel corrodes to produce the BM layer. Next and in sequence red, green and blue matches are covered in the portions where the BM spots do not exist to produce a phosphor screen. As shown in Fig. 1, there are individually phosphorus, red, green and blue in a conventional CRT. Since the red, green and blue phosphors use chemical elements that have several decay characteristics over time, especially ZnS: Ag, Cl or ZnS:? G, Al phosphors, which are used as blue phosphorus and take 100-200 microseconds , for blue phosphorus so that in decay it has 10% luminescence in co-u c. < Ion to its full luminis- ti-ic-ia (10% decay). Generally, in a CRT, the scanning speed of an electron beam scanning to find blue phosphorus is about 16m / s, as shown, the decay time for a conventional blue phosphor is very short compared to the speed of scanning an electron beam scanning the line in a CRT, conventional and therefore, a flicker phenomenon is present. Due to the phenomenon, a person who watches a TV. or a monitor may experience eye fatigue. In order to solve the problems as described above, an object of the invention is to provide a screen for a CRT, without flicker where it is reduced and a process to prepare it by a simple manufacturing process compared to that of a conventional CRT. In order to achieve this object, the present for a CRT, without flicker comprises a panel in which a black matrix is formed, layers of phosphorus, red, green and blue formed on panel regions where there is no black matrix and a UV phosphor layer, formed in the blue phosphor layer. In addition, the present invention provides a method for manufacturing a phosphor screen for a CRT, comprising the steps of forming the red and green phosphor layers on a panel, on which the black matrix is formed to form a blue phosphor layer on the panel on which the black matrix is formed, covering the blue phosphorus solution and drying it and forming a double phosphor layer overlying a UV phosphorus solution. over the blue phosphorus layer and drying. It is preferred that the wavelength of ultraviolet light emitted from UV phosphorus is in the range of 300-420 nm. It is preferred that the UV phosphorus is selected from the group consisting of: CaS: Pb; CaO: Pb; Y203: Gd; HfOa: Ti; Zn2Si04: Ti; ZnGa304: Li, Ti; Y ^ SiO ^ Ce; YaSi207: Ce, BaSi2Os: Pb and Ba2Si04: Pb. The preferred blue phosphorus is ZnS: Ag, Cl and ZnS: Ag, Al. Blue phosphorus produces a photoluminescence with a decay time greater than the emission time of an electron beam. For example, since the decay time of Ya03: Gd is within the range of 1 to 2 msec, it can be used to provide a longer decay time, which is the object of the invention. In addition, the method of the present invention produces a double phosphor screen of a blue phosphor and another ultraviolet screen by performing two coating and drying steps, and one exposure, development and washing step. Therefore, the method can produce a double phosphor screen without basically changing the conventional method and without increasing the manufacturing time. In the present invention, an aluminum layer is covered after the solution or slurry of a UV phosphor is placed on the blue layer of a conventional red, green and blue phosphor layer. Additional objects, advantages and characteristics of the invention will be established in the description that follows, and will also be evident to the technicians. The objects and advantages can be realized and obtained by the instrumentation and combinations indicated in the claims. BRIEF DESCRIPTION OF THE DRAWINGS. FIGURE 1 is a sectional cross-sectional view of a conventional phosphor screen. FIGURE 2 is a cross-sectional view of a phosphor screen of a double layer of phosphorus for a flickerless tube in which a UV phosphor layer is formed on a layer of blue phosphorus, according to a method of the present invention. In the following detailed description, only the preferred embodiment of the invention is presented, as a form of illustration in the best way that the inventor considers to carry out the invention. Therefore, the drawing and description are to be considered as illustrative and in no way as a restriction. Although the invention has been described with reference to a preferred embodiment, it should be understood that the invention is not limited to the preferred embodiment described herein. Representative example A glass panel is washed and made resistant to photography, including polyvinyl alcohol, sodium dichromate, polymer of propylene oxide and ethylene oxide, acrylic emulsion and pure water, coated on the inside of the panel, dried and reveals to prepare a template resistant to photography. Subsequently, graphite is placed on the resistant template formed and corroded using hydrogen peroxide to prepare the BM layer, removing the resistant photo. Subsequently a solution or slurry that includes phosphorus particles, pure water and polyvinyl alcohol, is put on the BM layer, and dried, exposed to light, revealed, washed and dried, to prepare a red phosphor screen and green. In addition, a blue phosphor ZnS: Ag, Cl and a UV phosphorus, are formed on the BM layer, and are simultaneously exposed to light, revealed and washed, to produce a double phosphor screen including a blue phosphor layer and a layer of UV phosphorus. The decay time of a phosphor screen formed by this method is longer than that of a screen formed only of a conventional blue phosphor. The phosphors that contain especially Pb or Gd, are useful because their decay times are expressed in units of milliseconds and it is known that BaSi305: Pb or Y203: Gd, is well illuminated by the jets of electrons. Experimental Examples 1-3: The determination of the optimum amount of blue phosphorus to be used in the coating material. When a blue phosphorus such as ZnS: Ag, Cl, and a UV phosphor, such as Zn2Si04: Ti, are coated on the panel as the first and second layers, the amount of blue phosphorus to be coated is an important factor in reducing the phenomenon of flicker. Therefore, the slurries are prepared with various amounts of blue phosphorus as shown in table 1. After forming a phosphor layer, first coating the slurry of each example in a panel, decay times and relative brightnesses are determined and the results are shown in the following table 1. Among the slurries prepared for experimental examples 1-3, the slurry of example 1, tube a long decay time and a gloss relative good, which was determined as the optimum amount of blue phosphorus to be used in the coating material. TABLE 1: the determination of the optimum amount of blue phosphorus. In. With grout Ex.ex. 1 Ex.e. 2 Ex.ex. 3 HaO 150g 150g 150g PVA 80g 83g 85g T.active 16g 16g 16g sensitizer 5g 5g 5g Z.?3:Ag,Cl lOOg 90g 8üy re-t.dec. sulmos 150 150 150 tablish 100 97 90 two laughs. NOTE: In. = ingredients, Con.lechada = condition of the slurry, Ex.ex. = experimental example, t.dec. = time decay.

Examples 4-6: determination of the optimum amount of UV phosphorus to be used in the coating material. In order to determine the optimum amount of UV phosphorus, such as Zn2Si04: Ti (400nm), for the second coating, the slurries were prepared with various amounts of UV phosphorus, which also affects the flicker reduction and the brightness of a CRT, as shown in table 2 (as the amount of UV phosphorus increases in the grout, the brightness decreases but also significantly decreases the blinking). The blue phosphor layer was formed on a glass panel (2x2cm), using the slurry from Experimental Example 2, and then the UV phosphor layer, was spin coated. Subsequently, the glass panel was placed in a TRC, removable and the luminescence spectrum was analyzed by evaluating it with an Os atrophotometer, (lOkv accelerated), the results are shown in table 2. Comparative example. The phosphorus layer was used using the same procedure as in Example 2, except that UV phosphorus, such as Zn2Si04: Ti, was not used. The characteristics of the phosphor screen were evaluated and the results are shown in table 2.

Table 2: determination of the optimal amount of UV phosphorus.

In. Ex.C EX. 4 Ex. 5 Ex. 6 H20 150g 150g 150g PVA 80g 80g 80g T.act. 16g 16g 16g sen. 5g 5g 5g Zn2Si04: Ti20g 40g 60g fos. UV T .dec. 150-t? Us 200mus 38mus 600mus (10% dec.) Brill? (%) 100 95 92 87 laugh. (blue) coord. 0.153 / 0.067 0.150 / 0.069 0.151 / 0.070 0.152 / 0.071 color (x / y) As shown in table 2, the relative blue brightness of the phosphor screen of the present invention decreases from 5 to 13%, according to the amount in the UV phosphor composition, but the decay time increases up to four times the decay time of the comparative example. There, it has been found that the phenomenon of flickering can be significantly reduced. The present invention can increase the decay time of blue phosphorus without changing the circuitry in a TRC, preparing a double screen of phosphorus comprising a blue phosphor and a UV phosphor. There a person who sees a TV, or a monitor having the phosphor of the present invention, will feel less eye fatigue. The decay time of UV phosphorus, which contains Pv, or Ti, and associates is an activator and is much greater than that of a conventional blue phosphorus, such as ZnSagCl, there blue phosphorus can be exited for a long time, in addition UV phosphorus can be used for the development of UV phosphorus, required by the UV phosphor screen, which can control the decay time of a blue phosphorus and can be applied to the cathode luminescence. In addition, a UV phosphor screen is easily formed only by coating and drying. There, in spite of a phosphor screen of a double phosphor layer, the present invention does not increase the defective rate in the manufactured screens and can control the decay time which is a disadvantage of a conventional blue phosphor. In this description only the prred embodiments of the invention have been shown and described, but it has to be understood by the invention. -s cet a_ of various combinations and modifications within its scope.

Claims (7)

1. RE I V I N D I CAC I S E 1.- A phosphor screen for a non-flicker cathode ray tube comprising: a panel on which a black matrix is formed; layers of red, green and blue phosphorus formed in the regions of the panel in which no black matrix has formed; ultraviolet phosphor layer formed on the blue phosphor layer.
2. 2. The phosphor screen for a cathode ray tube without flicker, according to claim 1, characterized in that the wavelengths of the ultraviolet light emitted from the ultraviolet phosphorus is in the range of 300-420 nm.
3. 3. The phosphor screen for a non-flicker cathode ray tube, according to claim 1, wherein the ultraviolet phosphor layer is selected from the group consisting of CaS: Pb; CaO: Pb, Y203: Gd; Hf02: Ti; Zn2Si04: Ti; ZnGa204: Li, Ti; Y2Si05: Ce; Y2Si307: Ce; BaSi2? 5: Pb and Ba3Si04: Pb.
4. 4. The phosphor screen for a cathode ray tube without flicker, according to claim 1, wherein the blue phosphorus is ZnS: Ag, Cl or ZnS: Ag, Al.
5. 5. A method for manufacturing a phosphor screen for a non-flicker cathode ray tube comprising the steps of: forming layers of red and green phosphorus on a panel for a cathode ray tube on which a black matrix is formed; form a layer of blue phosphorus on the panel on which the black matrix has been formed, coating with the blue phosphorus slurry and drying; and forming a layer of double phosphorus coating with a slurry of ultraviolet phosphorus on the blue phosphorus layer and drying.
6. 6. The method for manufacturing a phosphor screen for a cathode ray tube according to the claim 5, wherein the ultraviolet phosphorus is selected from the group consisting of CaS: Pb; CaO: Pb, Y203: Gd; Hf02: Ti; Zn2Si04: Ti; ZnGa204: Li, Ti; Y2Si05: Ce; Y2si207: Ce; BaSi205: Pb and Ba2Si04: Pb.
7. 7. Method for manufacturing a phosphor screen for a non-flicker cathode ray tube according to claim 5, wherein the blue phosphorus is ZnS: Ag, Cl < or ZnS: Ag, Al. RE SUME N A method for fabricating a phosphor screen for a non-flicker cathode ray tube, comprising the steps of forming red and green phosphor layers on a panel for a cathode ray tube on which a matrix is formed, forming a a layer of blue phosphorus on the panel on which the black matrix was formed covering the blue phosphorus slurry and drying and forming a double layer of phosphorous coating with a slurry of ultraviolet phosphorus on the blue phosphor layer and drying.