MXPA99001196A - Stretched mask for image pipe in colors and material for the masc - Google Patents

Abstract

The present invention relates to a stretched mask having a high tensile strength and favorable stretching properties at high temperatures and free of belt twist, and stretched mask material. A steel sheet with a low carbon content containing 70 ppm 170 ppm nitrogen based on weight is heat treated at a temperature at which recrystallization is not observed. The thermally treated material equipped with a protective pattern to form openings is subjected to chemical attack to form an aperture.

Description

STRETCHED MASK FOR IMAGE TUBE IN COLORS AND MATERIAL FOR THE MASK BACKGROUND OF THE INVENTION The present invention relates to a stretched mask for a tube of color images, which can be used for any type of tube of images in heat, for example, a shadow mask tube or a tube of an aperture grid, in computer color displays and color television. In color picture tubes for color television and computer visuals, a P? G mask is used. selection of color in such a way that the electron beams are applied to predetermined luminophores. As a screening mask, a shadow mask is used which is formed of a metal plate equipped with a large number of small holes or a grid of openings equipped with a large number of slits. When a tube of images to be cast is used continuously for a long period of time, the shadow mask as well as the grid of openings is heated due to the accelerated electrons coming into contact with it, and said grid mask is distorted by the Thermal expansion. This can cause the electron beams to gradually shift relative to the phosphor screen, which results in a color change in the color image.

In a color selection mask for a heat-imaging tube, a stretched color-discrimination mask such as a grid of openings, matted in a firm structure, is used together with a pressed member as a general shadow mask. The stretched color discrimination mask is formed in the following manner. A strip of steel with low carbon content, hot rolled, containing carbon in units of 0.0001% is cold rolled to form a sheet having a thickness of 0.02 mm to 0.30 mm. After the formation of a large number of grid elements in the cold-rolled steel strip by chemical etching, the steel strip is welded onto a structure placed under pressure applied in a direction reverse to the direction of stretching. Then, the pressure is removed to form tension by restoring the strength of the structure. Subsequently, to avoid the generation of secondary electrons, thermal radiation, formation of oxidation, etc., the material of the mask is subjected to a thermal treatment for 10 to 20 minutes in an oxidizing atmosphere at a temperature between 450 ° C and 470 ° C, thus darkening the surface of the mask. Conventionally, there is a likelihood that the tension of the grid elements of the color discrimination mask may be reduced during production, and this is a matter of great concern with regard to quality control. The problem is due to the fact that the grid elements elongate due to the progressive plastodefsrmación caused by the heat and tension during the enpegriculture of the color dissimilar mask material. The elements of the grid that have a low voltage recovery factor and a decreased voltage due to the important progressive creep formation have the problem that if vibrations are applied to the grid elements, for example, when the sound level of a speaker provided in the same cabinet as the cabinet containing the tube of heat images, the grid elements themselves vibrate with great amplitudes, causing a color shift in the color image. To solve the problem, document JP2548133 (B2) presents a color selection mechanism formed from a low carbon content sheet containing from 40 ppm to 100 ppm nitrogen. JP2683A74 (B2) proposes a sheet of low carbon steel containing 0.20 to 2.0% by weight of Cr and 0.10 to 3.0% by weight of Mo. However, these low carbon steel sheets have the problem that due to large residual stresses the tape portion of the aperture grid is unfavorably twisted after the heat treatment.

JP799025 (A) (USP 5,552,662) presents a method for producing an aperture grid using a material having a low residual stress. However, because the tensile strength is low, there is almost no change in the stress recovery factor. Accordingly, the belt of the opening grid can be broken when the opening grid is stretched. If the opening grid is stretched under a tension with which the tape does not break, the stretching tension undesirably decreases after the heat treatment. An object of the present invention is to provide a stretched color selection device for a color image tube having a minimal residual stress and free of problems such as "torsion and having a high voltage recovery factor. THE INVENTION The present invention offers a stretched mask for a color picture tube, stretched in a frame.The stretched mask is formed of a low carbon steel sheet containing from 70 ppm to 170 ppm of nitrogen based on the The steel sheet with low carbon content is thermoplasticized at a temperature at which recrystallization is not carried out, then a steel sheet with low carbon content is provided with a protection pattern to form openings and it undergoes chemical etching to form openings in the steel sheet with low carbon content.In addition, the present invention offers a stretched mask for a tube color image, which is stretched in a murcia. The stretched mask is formed from a sheet of steel with a low carbon content containing from 70 ppm to 170 ppm nitrogen by weight. The low carbon steel sheet contained in carbon has a voltage recovery factor of not less than 90% after heat treatment at a temperature at which recrystallization is not carried out. The voltage recovery factor is expressed as the ratio between a recovered voltage and an initial voltage. The recovered voltage is defined as follows. The length of a test piece when applied to a load of 500 N / mm2 at 25 ° C is defined as an initial length. And a tension under which the test piece has the initial length when the test piece is cooled to 25 ° C after heating to 455 ° C with the initial length maintained and conserved for 15 minutes at 455 ° C under a load of 100 N / mm2 is defined as a recovered voltage. Then, the steel sheet with low carbon content is provided with a protection pattern to form openings and is chemically etched to form an aperture in the steel sheet with a low carbon content. In the stretched mask, the steel sheet with low carbon content preferably contains, by weight, no more than 0.03% C, not more than 0.10% Si, from 0.10% to 0.60% Mn, not more than 0.10. % of P, not more than 0.10% of S, from 70 ppm to 170 ppm of N, as well as incidental impurities as components other than iron. In the stretched mask, the low carbon steel sheet preferably contains from 100 ppm to 170 ppm nitrogen by weight. In addition, the present invention provides a material for a stretched mask for a color picture tube. The material is a steel sheet with low carbon content containing 70 ppm to 170 ppm nitrogen on a weight basis. The low carbon steel sheet is pre-treated at a temperature at which no recrystallization is observed, and has a stress recovery factor of not less than 90%. In addition, the present invention provides a material for a stretched mask for a tube of color images. The material is a steel sheet with a low carbon content containing from 70 ppm to 170 ppm nitrogen by weight. The steel sheet with low carbon content has a stress recovery factor of not less than 90% after a heat treatment at a temperature at which no recrystallization is observed. The voltage recovery factor is expressed as the ratio between the recovered voltage and the initial voltage. The recovered voltage is defined as follows. The length of the test piece when a load of 500 N / mm2 at 25 ° C is defined as the initial length, and the tension under which the test piece has the initial length when the test piece is cooled to a temperature of 25 ° C after heating to 455 ° C with the maintenance and conservation of the initial length for 15 minutes at 455 ° C under a load of 100 N / mm2 is defined as a recovered tension. In the material for a stretched mask, the low carbon steel sheet contains, preferably, in weight, no more than 0.03% C, no more than 0.10% Si, from 0.10% to 0.60% Mn, not more than 0.10% of P, not more than 0.10% of S, from 70 ppm to 170 ppm of N, as well as incidental impurities as components other than iron. In the material for a stretched mask, the low carbon steel sheet preferably contains from 100 ppm to 170 ppm nitrogen, by weight. DESCRIPTION OF THE PREFERRED MODALITIES According to the present invention, a steel sheet with a low content of carbon having a specific value as regards nitrogen content in particular is heated to a temperature at which no recrystallization is observed, thus obtaining a stretched color discrimination mask that has a high recovery factor and exempt from problems such as breaking when the tape is subjected to stretching and twisting. A sheet of steel with low carbon content suitably used for the color discrimination mask stretched in accordance with the present invention contains no more than 0.03% (by weight, the same applies below) of C, not more than 0.10% in weight of Si, from 0.10% to 0.60% by weight of Mn, not more than 0.10% of P, not more than 0.10% of S, and the rest Fe as well as incidental impurities. In the low carbon steel sheet used in the present invention C forms carbide. If the C content is increased, the etching ability of the low carbon steel sheet in the color selection electrode production process is affected. Accordingly, the content of C is preferably not greater than 0.03%. If it forms silicate inclusions such as for example Mno-Si02 and Mn0-Fe0-Si02 and consequently affects the properties of chemical attack. Accordingly, the content of Si is preferably not greater than 0.10%. The content of Mn is preferably within the range of 0.10% to 0.60% from the perspective of the deoxidation action and the prevention of brittleness at high temperatures in the steelmaking process. If the P content rises, the steel hardens, and the rolling capacity of the steel decreases. Accordingly, the content of P is preferably not greater than 0.10%. S forms sulphide inclusions and therefore affects the chemical attack properties. Accordingly, the content of S is preferably not greater than 0.10%. The low carbon steel employed in the present invention preferably contains from 70 ppm to 170 ppm nitrogen in weight ratio, even more preferably from 100 ppm to 170 ppm, preferably still greater than 100 ppm to 150 ppm. If the nitrogen content is less than 70 ppm, the strength is reduced. If the nitrogen content is greater than 170 ppm, the grain boundaries become larger, which is unfavorable from the perspective of the etching properties. After lamination, the low carbon steel employed in the present invention is heat treated under conditions in which no recrystallization is observed in a reducing or non-oxidizing atmosphere. Accordingly, the tensile strength becomes greater than the tensile strength of conventional materials having small residual stresses, and it is possible to obtain progressive creep properties at favorable high temperatures. Preferably, the heat treatment conditions are as follows. The heat treatment temperature is within the range of 450 ° C to 650 ° C, and the thermal treatment time is within the range of 3 seconds to 120 seconds. A heat treatment temperature greater than 650 ° C is not preferable because recrystallization could occur. If the heat treatment temperature is less than 450 ° C, no improvement in properties can be achieved by thermal treatment. The present invention will now be described by way of examples. Example 1: Low carbon steel materials of 0.1 mm thickness made from materials A to G, whose chemical compositions are illustrated in Table 1 below, were treated for 45 seconds at a temperature comprised between 540 ° C and 560 ° C in a mixed atmosphere of hydrogen and nitrogen in a continuous tempering furnace. The low-carbon, tempered steel materials were coated on both sides thereof with a water-soluble casein protection. After drying, the protections on both sides of each material were designed in patterns by using a pair of dry glass plates with both reverse and reverse patterns drawn there, respectively. It should be noted that the protection patterns were formed in two different ways in such a way that the direction of opening of the slits formed by chemical attack using a protection pattern was parallel to the rolling direction, and the opening direction of the slits. formed by chemical attack using the other protection pattern was perpendicular to the rolling direction. Afterwards, exposure, hardening and firing processes were carried out. Subsequently, the patterned protective surfaces were sprayed with a ferric chloride solution having a temperature of 60 ° C and a specific gravity of 48 ° Be as a chemical attack liquid by using a spray to carry out the chemical attack . After the chemical etching process, a rinse was carried out, and the protection was removed with an alkaline aqueous solution, followed by washing and washing to produce a color discrimination mask. Each mask of heat discrimination obtained was evaluated by the following evaluation method. The results of the evaluation appear in Table 2, below. Regarding the slit direction in Table 2, the term "parallel" indicates that the openings formed by the chemical attack were parallel to the rolling direction of the material, and the term "perpendicular" means that the openings were perpendicular to the Rolling direction. The transmission is the proportion (expressed as a percentage) between the opening area and the area of a region located between the openings at both ends. Table 1 C Yes Mn P S N Balance Material 0.007 0.01 0.45 0.016 0.007 0.0080 Fe and im- To incidental purities Material 0.006 0.01 0.43 0.014 0.007 0.0100 Fe and im- B incidental purities Material 0.007 O.01 0.46 0.013 0.006 0.0122 Fe and im- C incidental purities Material 0.007 0.01 0.44 0.016 0 .O08 0.0140 Fe ei - D incidental purities Material 0.006 0.01 0.43 0.016 0.008 0.0150 Fe ei - E Incidental purities Material 0.008 0.01 0.45 0.015 0.007 0.0163 Fe and im- F purities incident them Material 0.008 0.01 0.42 0.013 0.009 0.0170 Fe and im- G incidental purities (Evaluation method) 1. Tape twisting After stretching each mask of color discrimination under a train load 30 N / mm2, the presence or absence of tape twist is visually checked. 2. Tensile strength The tensile strength was measured in accordance with JIS Z2241 by the use of a test piece No. 5 in accordance with JIS Z2201. 3. Tension recovery evaluation method Two different types of test pieces of 510 mm length and 25 mm width were prepared. A type of test piece was formed in such a way that the longitudinal direction thereof was parallel to the rolling direction of the material. The longitudinal direction of the other type of test piece was perpendicular to the direction of rolling of material. Each test piece was stopped by means of the holding portions of a tension testing machine and stretched in the longitudinal direction at a temperature of 25 ° C under an initial load of 500 N / mm2. The distance between the clamping portions at this time was measured as the initial length of the test piece. With the distance between the holding portions maintained at the initial length, the test piece between the clamping portions was heated to 455 ° C at a heating rate of 1 ° C / minute in a heating furnace with an air atmosphere . The test piece was maintained for 15 minutes at 455 ° C under a load of 100 N / mm2. After, the cooling began. With the distance between the clamping portions established in the initial length, the load in the longitudinal direction of the test piece was measured at a temperature of 25 ° C as a recovered voltage, and the voltage recovery factor was obtained by factor tension recovery (%) = (tension recovered / initial tension) x 100 Comparative example 1: A steel material with low carbon content of 0.1 mm thickness having a composition consisting essentially, in weight ratio, of 0.006% of C, 0.01% of Si, 0.44% of Mn, 0.010% of P, 0.008% of S, 0.0060% of N, and the rest of Fe as well as incidental impurities was treated during 45 seconds at a temperature between 540aC and 560 ° C in a mixed atmosphere of hydrogen and nitrogen in a heating oven. The tempered material was subjected to chemical attack in the same manner as in Example 1 in order to produce a color discrimination mask. The color discrimination mask was evaluated in the same manner as in example 1. The results of the evaluation are shown in Table 2. Comparative Example 2: A cast discrimination mask was produced in the same manner as in the Comparative Example 1 except that the tempering process was not carried out. The color discrimination mask was evaluated in the same manner as in Example 1. The results of the evaluation are shown in Table 2. Comparative Example 3: A cast discrimination mask was produced in the same manner as in the Comparative Example 1 by using material B in Example i except that material B was not tempered. The color discrimination mask was evaluated in the same manner as in Example 1. The results of the evaluation are shown in Table 2. Comparative Example 4: A steel material with a low carbon content of 0.1 mm thickness having a composition that essentially consists, in weight ratio, of 0.007% of C, 0.01% of Si, 0.45% of Mn, 0.015% of P, 0.008% of S, 0.0200% of N, and the rest of Fe and incidental impurities was treated for 45 seconds at a temperature between 540aC and 560oC in a mixed atmosphere of hydrogen and nitrogen in a heating furnace. The tempered material was subjected to chemical attack in the same manner as in Example 1 in order to produce a color discrimination mask. The heat discrimination mask was evaluated in the same manner as in Example i. The results of the evaluation appear in Table 2. In Comparative Example 4, it was impossible to carry out a uniform chemical attack. It was considered that due to the impossibility of carrying out a uniform chemical attack, the linearity of the tape was insufficient, and the tape was twisted. Table 2 Tempering Direction of Transmittance Twist slit (%) of tape Example 1 Material A performed parallel 22.5 none performed perpendicular 22.6 none Material B performed parallel 22.6 none performed perpendicular 22.5 none Material C performed parallel 22.5 no performance perpendicular r 22.4 none Material D performed parallel 22.5 none performed perpendicular 22.4 none Material E made parallel 22.5 none made perpendicular 22.6 none Material F carried out parallel 22.5 no real perpendicular hoisting 22.4 none Material G made parallel JÍ.2 * or no perpendicular referencing 22.4 none Ex. Comp. 1 performed parallel 22.5 none performed perpendicular 22.4 none Ex. Comp. na realized parallel 22.6 twisted not realized perpendicular 22.6 twisted Ej. Comp. 3 not realized parallel 22.6 twisted not performed perpendicular 22.5 twisted Ex. Comp. 4 real parallel lifting 20.1 twisted made perpendicular r U «-í. twisted Stress recovery factor (%) Example 1 Material A 90 92 Material B 95 95 Material C 96 96 Material D 96 96 Material E 97 97 Material F 97 97 Material G 97 97 Ex. Comp. 1 86 89 Ex. Comp. 2 84 87 Ex. Comp. 3 88 89 Ex. Comp. 4 88 89 As described above, the mask stretched for a tube , a -? ^ t: "» '».," ^' = - "" ", a.-m. ' - '• - •. "! The color images according to the present invention have progressive plating properties at favorable high temperatures and are free of problems such as for example breakage when stretching and belt twisting in contrast to conventional stretched masks by the use of a steel sheet with low carbon content or raw material. Therefore, it is possible to obtain a tube of high quality cast images.

Claims (10)

1. CLAIMS 1. A stretched mask for a tube of color images, which is stretched on a frame, said stretched mask comprises a sheet of steel with low carbon content containing from 70 ppm to 170 ppm nitrogen, by weight, said sheet steel with low carbon content is heat treated at a temperature at which recrystallization is not caused, said steel sheet with low carbon content is equipped with a protection pattern to form openings and said sheet is subjected to a chemical attack with the object of forming openings in said steel sheet with low carbon content.
2. 2. A stretched mask for a color image tube, stretched on a frame, said stretched mask comprises: a sheet of steel with low carbon content containing from 70 ppm to 170 ppm nitrogen by weight, said steel sheet with Low carbon content has a stress recovery factor of not less than 90% after heat treatment at a temperature at which recrystallization is not caused, said stress recovery factor is expressed as the ratio between the recovered voltage and the initial tension, said recovered tension is defined in such a way that a length of the test piece when a load of 500 N / mm2 is applied to it at a temperature of 25 ° C is defined as initial length, and a low tension which the test piece has the initial length when the test piece is cooled to 25 ° C after being heated to 455 ° C with the maintenance and conservation of the initial length for 15 minutes At a temperature of 455 ° C under a load of 100 N / mm2, it is defined as recovered tension, said sheet of steel with low carbon content is then equipped with a protection pattern to form openings and is chemically etched. object of forming openings in said steel sheet with low carbon content.
3. A stretched mask according to claim 1 or claim 2, wherein said sheet of steel with low carbon content contains, by weight, no more than 0.03% C, not more than 0.10% Si, of 0.10. % to 0.60% of Mn, not more than 0.10% of P, not more than 0.10% of S, from 70 ppm to 170 ppm of N, as well as incidental impurities as components other than iron.
4. A stretched mask according to claim 1 or claim 2, wherein said low carbon steel sheet contains from 100 ppm to 170 ppm nitrogen, by weight.
5. A stretched mask according to claim 1 or claim 2, wherein said steel sheet with low carbon content contains, by weight, no more than 0.03% C, not more than 0.10% Si, of 0.10% to 0.60% of Mn, not more than 0.10% of P, not more than 0.10% of S, from 100 ppm to 170 ppm of N, as well as incidental impurities or components other than iron.
6. 6. A material for a stretched mask for a tube of color images, said material comprises: a steel sheet with low carbon content containing from 70 ppm to 170 ppm nitrogen, by weight, said steel sheet with low The carbon content is heat treated at a temperature at which no recrystallization is observed, and said sidewalk sheet with low carbon content has a stress recovery factor of not less than 90%.
7. 7. A material for a stretched mask for a tube of color images, said material comprises: a steel sheet with low carbon content containing from 70 ppm to 170 ppm nitrogen, by weight, said steel sheet with low content of carbon has a stress recovery factor of not less than 90% after a heat treatment at a temperature at which no recrystallization is observed, said stress recovery factor is expressed as a ratio between the recovered tension and the initial stress , said recovered stress is defined in such a way that a length of a test piece when applied to a load of 500 N / mm2 to said piece at a temperature of 25 ° C is defined as initial length, and a tension under which the test piece has the initial length when the test piece is cooled to 25 ° C after heating to 455 ° C with the initial length maintained and conserved for 15 minutes at 455 ° C under a load of 100 N / mm2 is defined as a recovered voltage.
8. A material for a stretched mask according to claim 6 or claim 7, wherein said sheet of steel with low carbon content contains, by weight, na more than 0.03% C, not more than 0.10% of Yes, from 0.10% to 0.60% of Mn, not more than 0.10% of P, not more than 0.10% of S, from 70 ppm to 170 ppm of N, as well as incidental impurities as components other than iron.
9. 9. A material for a stretched mask, according to claim 6 or claim 7, wherein said low carbon steel sheet contains, from 100 ppm to 170 ppm nitrogen, by weight.
10. 10. A material for a stretched mask according to claim 6 or claim 7, wherein said low carbon steel sheet contains, by weight, no more than 0.03% C, not more than 0.10% of Yes, from 0.10% to 0.60% of Mn, not more than 0.10% of P, not more than 0.10% of S, from 100 ppm to 170 ppm of N, as well as incidental impurities as components other than iron. '.jt v? > go