JP2007073421A - Shadow mask and picture tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shadow mask that is resistant to deformations such as a depression even when an impact or vibrations are applied to a cathode-ray tube and/or a TV set, and a picture tube having the shadow mask. <P>SOLUTION: The shadow mask has a number of penetrating holes 11 arranged in a horizontal direction X and a perpendicular direction Y of a mask body 1a, the penetrating holes 11 being formed of a rear-side hole part 13 and a front-side hole part 12 that communicate with each other, wherein the rear-side hole part 13 is located on a side on which an electron beam is incident, while the front-side hole part 12 is located on a side from which the electron beam exits. The shadow mask forms a beam spot having a predetermined shape on a phosphor layer of the cathode-ray tube. A number of recesses 15 are formed in a center portion of a surface of the shadow mask located on the side on which the electron beam is incident. The recesses 15 are preferably half-etching holes of one or a plurality of types of selected from circular, rectangular, and polygonal shapes. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shadow mask and a picture tube, and more particularly to a shadow mask excellent in impact strength that is preferably used for a flat color CRT with a flat front panel surface, and a picture tube equipped with the shadow mask. .

  FIG. 7 is a cross-sectional view showing an example of a schematic structure of a color cathode ray tube (also referred to as a picture tube). The CRT 101 is generally a vacuum tube composed of a substantially rectangular front panel disposed on the front surface and a funnel-shaped funnel connected to the front panel. In such a cathode ray tube 101, an electron gun 103 is provided at the neck portion of the funnel. The electron gun 103 emits three types of electron beams 105 for causing the three primary color (R, G, B) phosphors 102 applied to the inner surface of the front panel to emit light.

  On the inner surface of the front panel, there is provided a shadow mask 1 facing the phosphor 102 with a slight gap. The shadow mask 1 has dot-shaped circular holes or slot-shaped rectangular holes that are regularly arranged so as to pass the electron beam 105 from the electron gun 103 and hit a predetermined phosphor 102. In the color cathode ray tube 101 having such a configuration, the three types of electron beams 105 emitted from the electron gun 103 are scanned horizontally and vertically by a magnetic field generated by the deflection yoke 104, pass through the shadow mask 1, and have a predetermined content of the phosphor 102. Landing at the position, the phosphor 102 emits light to form an image.

  FIG. 10 is a schematic plan view showing an example of a shadow mask provided in the color cathode ray tube. Note that the shadow mask of FIG. 10 is an example of a shadow mask having a rectangular hole. The shadow mask 1 has a substantially rectangular mask body 1a, and the mask body 1a has slots 2 (2a, 2b, 2c, 2d) having substantially rectangular through holes penetrating in the thickness direction. Are arranged in the horizontal direction X and the vertical direction Y in plan view. In the present application, a slot type unit composed of a through hole and a front side hole part and a back side hole part forming the through hole is referred to as a “slot”. In FIG. 10, reference numeral 6 denotes a center point (also referred to as a center) represented by the intersection of two diagonal axes 5 and 5 that connect opposite corners of the mask body 1a, and reference numeral 3 denotes the center. A horizontal axis that passes through the point 6, and a reference numeral 4 is a vertical axis that passes through the center point 6. The slot 2a is a slot at the center point 6 of the mask body 1a, the slot 2b is an outer peripheral slot on the vertical axis 4, the slot 2c is an outer peripheral slot on the horizontal axis 3, and the slot 2d is a pair. Reference numeral 1b denotes a skirt portion that is outside the mask main body 1a and is bent by press working. FIG. 10 is a schematic diagram, and the slot is greatly exaggerated.

FIG. 11 is a schematic plan view showing the shape of the slot formed in each part of the mask main body 1a. Reference numeral 11 denotes a through hole included in the slot. The through hole 11 is formed by communicating the front side hole 12 and the back side hole 13 formed by etching. The back hole 13 is formed on the side on which the electron beam 7 is incident, and the front hole 12 is formed on the side on which the electron beam 7 is emitted. The back side hole 13 and the front side hole 12 are formed to have a substantially rectangular shape, and the front side hole 12 is formed with a large area so as not to get in the way after the electron beam 7 passes through the through hole 11. ing. The shadow mask listed in Patent Document 1 below is an example of a conventionally proposed shadow mask.
JP-A-5-6741

  A cathode ray tube equipped with a shadow mask as described above is deformed by a shock or vibration applied to the cathode ray tube or the TV set at the time of shipment or transportation of the product, or at the time of shipment or transportation after being incorporated into the TV set. There is a problem.

  That is, in recent years, a thin cathode ray tube having a high deflection angle as shown in FIG. 7 has been developed, and the incident angle to the slot formed in the shadow mask has been remarkably increased particularly at the outer peripheral portion. Therefore, the demand for thinning and flattening of the front panel surface is remarkable in the recent cathode ray tube, and the flattening and thinning of the shadow mask mounted on the inner surface of the front panel are also progressing, and the electron beam is In order not to get in the way after passing through the through hole, the front side hole part in the outer peripheral part is formed with a large area.

  When an impact is applied to the cathode ray tube or TV set provided with such a shadow mask, a substantially elliptical recess 121 is generated like a wave in the central portion of the shadow mask (see FIG. 13A). Changed to a longitudinal wave 122 extending in the vertical direction (see FIG. 13B), and thereafter, a deformation behavior was observed in which the longitudinal wave 123 flows and disappears in the lateral direction (see FIG. 13C). ). At this time, in the conventional shadow mask 1, as shown in FIG. 12, it was confirmed that the ratio with which a dent remains in the center part is high. If the dent remains in the shadow mask 1, the predetermined phosphor 102 is not correctly irradiated with the electron beam. As a result, the color image of the color cathode ray tube 101 is not faithfully reproduced and the image quality is remarkably deteriorated.

  The present invention has been made in order to solve the above-described problems, and has as its object the provision of a shadow mask and its shadow mask that are unlikely to retain deformation such as dents even when impact or vibration is applied to a CRT or TV set. It is to provide a picture tube.

  In the course of conducting research to solve the above problems, the inventor reduced the weight of the shadow mask and devised the center of gravity in the thickness direction of the central portion where the dent remained, thereby causing a dent for a moment due to impact or the like. Even if this occurred, it was found that the dent hardly remained as a permanent dent, and the present invention was completed based on the knowledge.

  In order to solve the above problems, the shadow mask of the present invention has a through-hole in which the back side hole on the side on which the electron beam is incident and the front side hole on the side on which the electron beam is emitted communicates with the mask body in the horizontal and vertical directions. In a shadow mask that is arranged in a large number in a direction and forms a beam spot of a predetermined shape on a phosphor of a cathode ray tube, a large number of recesses are formed at least in the central part of the shadow mask surface on which the electron beam is incident It is characterized by that.

  According to the present invention, since a large number of recesses are formed at least in the central portion of the shadow mask surface on the side on which the electron beam is incident (hereinafter also referred to as the electron gun side), particularly the central portion of the shadow mask is reduced in weight. can do. As a result, even when an impact or vibration is applied to the cathode ray tube or the TV set, a large deformation based on the weight of the shadow mask is unlikely to occur, so that the deformation behavior of the entire mask is reduced, and permanent dents can be prevented as a result.

  In addition, since the conventional shadow mask has a front hole with a large opening area formed on the front panel side, the center of gravity in the thickness direction, especially in the center, exists near the shadow mask surface on the electron gun side. In the shadow mask of the present invention, since a large number of recesses are formed at least in the central part of the shadow mask surface on the electron gun side, the center of gravity in the thickness direction at the central part is shifted to the center side in the thickness direction. . The shadow mask having such a position of the center of gravity is a shadow mask having a small ratio of permanent dents remaining even by impact or vibration applied to a cathode ray tube or a TV set, and having excellent impact resistance.

  In the shadow mask of the present invention, the concave portion is formed only in the central portion of the mask body.

  According to the present invention, since the concave portion formed on the surface of the shadow mask on the electron gun side is formed only in the central portion of the mask body, particularly the weight of the central portion can be relatively reduced, and at the central portion, The center of gravity in the thickness direction can be shifted to the center side in the thickness direction. As a result, it is possible to prevent permanent dents from remaining due to shock or vibration applied to the cathode ray tube or the TV set.

  In the shadow mask of the present invention, the opening area ratio of the concave portion per unit area in the region where the concave portion is formed decreases continuously or stepwise from the center of the mask body toward the outer peripheral side. Features.

  According to this invention, since the opening area ratio of the concave portion included per unit area in the region where the concave portion is formed decreases continuously or stepwise from the center of the mask body toward the outer peripheral side, The partial weight of the shadow mask can be gradually reduced from the outer peripheral side toward the center. Such a shadow mask has a very regular strength balance, so that it is difficult for the shadow mask to be deformed even when stress such as impact is applied after being mounted on the cathode ray tube, and it is possible to prevent permanent dents from remaining.

  The shadow mask of the present invention is characterized in that the recess is one or more half-etched holes selected from a circle, a rectangle and a polygon.

  According to this invention, since the recess is one or more half-etched holes selected from a circle, a rectangle, and a polygon, etching can be performed together with the etching of the back side hole. As a result, a shadow mask in which permanent dents are hardly left can be obtained at low cost.

  In the shadow mask of the present invention, the horizontal width of the front hole formed in the central portion of the mask body is smaller than the horizontal width of the front hole formed on the left and right sides of the mask main body. To do.

  According to the present invention, since the horizontal width of the front hole formed in the central portion is relatively small, the center of gravity of the shadow mask in the thickness direction is coupled to the center of the thickness direction in combination with the recess. Can be shifted. A shadow mask with such a structural form can reduce the weight of its central part, and it is difficult for large dents to occur even when impact is applied. As a result, the percentage of permanent dents remains small, resulting in high impact resistance. It becomes an excellent shadow mask.

  In order to solve the above problems, a picture tube of the present invention has the shadow mask of the present invention.

  According to the present invention, since the shadow mask as described above is provided, even when an impact or vibration is applied to the cathode ray tube or the TV set, a color image can be faithfully reproduced and image quality does not deteriorate.

  According to the shadow mask of the present invention, the center portion can be particularly reduced in weight, and the center of gravity in the thickness direction at the center portion is shifted to the center side in the thickness direction. Alternatively, large deformation based on the weight of the shadow mask hardly occurs due to vibration. As a result, it is possible to prevent permanent dents from remaining in the shadow mask. Further, according to the picture tube of the present invention, even when an impact or vibration is applied to the cathode ray tube or the TV set, a color image can be faithfully reproduced, and image quality does not deteriorate.

  In the shadow mask of the present invention, since many concave portions are formed on the electron gun side, the surface area is increased by the concave portions. As a result, it also has an effect of reducing the doming phenomenon (doming pattern, which is a phenomenon in which the shadow mask is deformed by heat generated by the electron beam and color unevenness occurs) when the electron beam is irradiated. As a result, it is preferable as a shadow mask for a thin cathode ray tube having a high deflection angle that is easily affected by a doming phenomenon.

  The shadow mask and picture tube of the present invention will be described below with reference to the drawings. The present invention is not limited to the embodiments described below, but includes various forms including the technical idea of the present invention.

  The shadow mask of the present invention is obtained by etching through a thin metal plate to form through holes having a predetermined shape in a predetermined pattern. The pattern is usually formed by arranging the through holes in a substantially close-packed structure or a structure similar thereto. The shadow mask having such a shape is attached to a cathode ray tube and used to form a beam spot having a predetermined shape on the phosphor. The shape of the beam spot may be either a circular shape or a slot shape having a substantially rectangular shape, and the present invention can be applied to any case. 1 to 3, a slot-type shadow mask having a rectangular through-hole that forms a slot-shaped beam spot in the phosphor will be described. In FIG. 6, a circular beam spot is formed in the phosphor. A dot-type shadow mask having circular through holes will be described. The positional relationship of the through holes formed in each part is the same as that described for the slot type shadow mask as shown in FIGS.

  FIG. 1 is a partial plan view and a partial sectional view showing an example of the shadow mask of the present invention. 1A shows the planar shape and cross-sectional shape of the slot formed at the center of the shadow mask, and FIG. 1B shows the planar shape and cross-sectional shape of the slot formed on the outer periphery in the right direction on the horizontal axis of the shadow mask. The shape is shown.

  In the shadow mask shown in FIG. 1, the back side hole 13 on the side where the electron beam enters (hereinafter referred to as the electron gun side) and the front side hole 12 on the side where the electron beam exits (hereinafter referred to as phosphor side) communicate with each other. A plurality of slots (2a, 2c) having substantially rectangular through-holes 11 arranged in the horizontal direction X and the vertical direction Y of the mask body 1a to form a rectangular beam spot on the cathode ray tube phosphor. It is a mask. In the shadow mask 1 of the present invention, a large number of recesses 15 are formed at least at the center of the shadow mask surface on the electron gun side.

  As shown in FIG. 1, the through-hole 11 constituting the slot is a slot-type rectangular hole formed by a back-side hole 13 on the electron gun side and a front-side hole 12 on the phosphor side. The front side hole 12 is formed with a larger opening area than the back side hole 13. Such a through hole 11 allows only an electron beam that is not shielded by the end or side wall of the back side hole 13 to pass therethrough, and forms a slot type beam spot at a predetermined size on a phosphor of the cathode ray tube with a predetermined size.

  As shown in FIGS. 10 and 11, the positional relationship between the front hole 12 and the back hole 13 constituting the slot is formed in the slot 2a formed in the center of the shadow mask 1 and in the outer periphery. The slot 2b, 2c and 2d are different. Further, even in the slots 2b, 2c, and 2d formed in the outer peripheral portion, the positional relationship between the front side hole portion 12 and the back side hole portion 13 is the slot 2b formed in the vertical direction Y as shown in FIG. And the slot 2c formed in the horizontal direction X is different from the slot 2d formed in the diagonal direction. Such a difference at the outer peripheral portion prevents the electron beam from being blocked by the outer peripheral side wall of the front hole portion 12. With this positional relationship, a slot-type beam spot can be formed at a predetermined size and at a predetermined position on the phosphor of the cathode ray tube.

  Specifically, since the electron beam is irradiated almost straight toward the shadow mask 1 at the center of the shadow mask 1, as shown in FIGS. 1 (A) and 11 (a), the back side hole is formed. The center of 13 and the center of the front side hole part 12 should just be formed so that it may become a substantially the same position. On the other hand, since the electron beam is irradiated obliquely toward the shadow mask 1 at the outer periphery of the shadow mask 1, the center of the back side hole 13 and the center of the front side hole 12 are shown in FIG. 11 (c), it is necessary to change the position depending on the position where the slot is formed. That is, the surface hole portion 12 is formed so as to shift outward as compared with the back side hole portion 13 as the position where the slot is formed goes to the outer peripheral portion side.

  Next, the recess will be described.

  A large number of the recesses 15 are formed in at least the central portion of the shadow mask surface on the electron gun side and in portions other than the back side hole portion 13. In particular, the recess 15 is preferably formed only in the central portion of the mask body 1a. By forming the concave portion 15 only in the central portion, the central portion can be relatively reduced in weight, and the center of gravity of the shadow mask in the thickness direction at the central portion can be shifted to the center side in the thickness direction. As a result, the cathode ray tube or TV set equipped with such a shadow mask can further suppress the occurrence of a dent in the central portion where the dent is likely to occur even when an impact or vibration is applied to the cathode ray tube or the TV set. At the same time, it is possible to effectively prevent permanent dents from remaining.

  In addition, if the center part which formed the recessed part 15 is made comparatively lighter than an outer peripheral part, a center part will be supported by the outer peripheral part which became relatively heavy. As a result, even if a stress such as a drop impact is applied after being mounted on the cathode ray tube, the shadow mask 1 is hardly deformed such as a dent.

  In the present application, the “center portion” means the length of the imaginary line when a phantom line is drawn radially from the center 6 (see FIG. 10) of the mask body 1a which is a perforated portion to the periphery of the mask body 1a. Of these, the region from the center 6 to 1/2 to 1/3 is said. Although this region varies slightly depending on the size of use of the shadow mask, it is preferable to form the recess 15 in at least the region from the center 6 to 1/2 to 1/3 in order to achieve the object of the present application. Further, “at least” of “at least the central portion” means that if the concave portion 15 is formed in a portion other than the central portion, the strength of the outer peripheral portion is lowered and the deformation tends to occur. Therefore, it is necessary to provide the concave portion 15 in the outer peripheral portion. However, if it is provided temporarily, it means that it does not matter as long as it does not cause a decrease in strength.

  The recess 15 is preferably one or more half-etched holes selected from a circle, a rectangle, and a polygon. The concave portion made of a circle may be a perfect circle, an ellipse, or a similar circular shape, and the size thereof is not particularly limited. For example, the diameter L of the concave portion made of a perfect circle or a substantially perfect circle is 50 μm or more and 150 μm or less. The range can be given as an example. In addition, the rectangular concave portion may be square or rectangular, and the length of each side is not particularly limited, but the length L of one side may be in the range of 50 μm or more and 150 μm or less. Further, the polygonal concave portion may be triangular, pentagonal, hexagonal or octagonal, and the size thereof is not particularly limited, but is preferably formed to have the same size as the circular or rectangular concave portion.

  Such a recess 15 is formed as a half-etched hole. Usually, a pattern for forming the recess 15 is formed together with an etching mask used when the backside hole 13 is wet-etched, and the etching mask is used to form the backside hole 13. Therefore, the shape, size, depth, etc. of the recess 15 can be controlled by the recess forming pattern formed on the etching mask. In addition, since a recessed part is formed as a half-etching hole, in the recessed part which consists of a rectangle or a polygon, the edge is rounded and actually becomes a substantially rectangle or a substantially polygon.

  An example of the depth d of the concave portion 15 is a range of 1/3 to 2/3 of the plate thickness. Since the recess 15 is formed as an etching hole, the depth d of the recess 15 increases as the size of the opening of the recess 15 increases, and decreases as the size of the opening decreases. Therefore, when adjusting the depth d of the recess 15, it is necessary to set it in consideration of the size of the recess 15.

  Next, a specific example of forming the recess 15 will be described. FIG. 2 is a plan view showing an example when the central portion of the shadow mask of the present invention is viewed from the phosphor side (side from which the electron beam is emitted). FIG. 3 is a plan view showing the central portion of the shadow mask of the present invention. It is a top view which shows an example when it sees from the side (side where an electron beam injects). In the present invention, the concave portion is not formed on the phosphor side, and the concave portion 15 is formed only on the electron gun side. In the formation pattern of the recesses 15, as illustrated in FIGS. 3A and 3B, the circular recesses 15 a or the rectangular recesses 15 b can be arranged in a substantially close-packed structure or a structure similar thereto. In FIG. 3, the upper and lower concave portions 15 are arranged so as to be arranged in three rows on the left and right, but is not limited to the illustrated example, and may be formed between the back side hole portions 13 arranged in the vertical direction. Absent.

  In the shadow mask 1 of the present invention, the center of gravity in the thickness direction of the shadow mask is shifted to the center side in the thickness direction by forming a large number of recesses 15 on the surface of the shadow mask on the electron gun side as described above. It has structural features. In the conventional shadow mask, since the front side hole 12 having a large opening area is formed on the phosphor side, the center of gravity of the shadow mask in the thickness direction exists in the vicinity of the surface of the shadow mask on the electron gun side. The shadow mask of the present invention having a center of gravity position on the center side of the LED has a smaller ratio of permanent dents remaining in the central portion thereof than the conventional shadow mask even by impact or vibration applied to a CRT or TV set. It was confirmed that the shadow mask had excellent impact properties.

  The center of gravity in the thickness direction shifted by forming the recess 15 is preferably in the range of 1/3 to 2/3 from the surface on the electron gun side when the thickness T of the shadow mask is 100. . The position of the center of gravity can be determined from an area distribution in the thickness direction of the cross section obtained by taking a cross-sectional photograph of the shadow mask.

  Further, in the present invention, as shown in FIG. 1, the width W1 in the horizontal direction of the front hole 12 formed in the central portion of the mask main body 1a is set to the front hole 12 formed on the left and right sides of the mask main body 1a. Can be made smaller than the horizontal width W2.

  Since the electron beam is obliquely incident on the through hole 11 on both the left and right sides of the mask body 1a, the front side hole portion 12 is shifted to the outer peripheral side with respect to the through hole so as not to shield the electron beam that has passed through the through hole 11. In addition, it is formed with a large width W2. However, since the electron beam is directly incident on the through hole 11 in the central portion of the mask body 1a, the front side hole portion 12 does not need to be shifted to the outer peripheral side with respect to the through hole 11, and the front side hole in the outer peripheral portion It is not necessary to be formed in the same size as the portion 12. Furthermore, the shadow mask of the present invention has a concave portion 15 formed on the surface on the electron gun side, particularly in the central portion, and shifts the center of gravity in the thickness direction toward the center in the thickness direction from the viewpoint of achieving the above effect. The concave portion 15 is formed on the surface on the electron gun side, and the horizontal width W1 of the front side hole portion 12 formed in the central portion is set as the horizontal width of the front side hole portion 12 formed on the left and right sides of the mask body 1a. It can be set as the structure made smaller than W2. By setting the horizontal width W1 of the front side hole portion 12 formed in the central portion to W1 <W2, the center of gravity position in the thickness direction is the center in the thickness direction as compared with the conventional case of W1 = W2. There is an advantage that it can be easily shifted in the direction.

  The horizontal width W1 of the front side hole portion 12 formed in the central portion of the mask main body 1a is made smaller than the horizontal width W2 of the front side hole portion 12 formed on both the left and right sides of the mask main body 1a and penetrates. In order to make the holes 11 have the same dimensions, an etching pattern for forming a slot in the central portion is devised. Specifically, the etching pattern of the front side hole portion 12 in the central portion is made smaller than the etching pattern of the front side hole portion 12 in the outer peripheral portion, and the etching pattern of the back side hole portion 13 in the central portion is changed to the back side hole portion in the outer peripheral portion. If the etching pattern is made larger than the etching pattern 13, the central portion of the through hole 11 and the outer peripheral portion of the through hole 11 can have the same size, and at the same time, the front side hole portion 12 and the back side hole portion 13 Can be shifted to the center side in the thickness direction. Shifting the ridge line portion 14 toward the center in the thickness direction is effective for shifting the center of gravity in the thickness direction toward the center in the thickness direction.

  FIG. 4 is a schematic front view for explaining an example of a mode in which the opening area ratio of the concave portion of the shadow mask is changed continuously or stepwise, and FIG. 5 is a schematic front view for explaining another example. FIG. In the shadow mask of the present invention, the opening area ratio of the recess 15 included per unit area in the region where the recess 15 is formed (center portion) is from the center 6 (see FIG. 10) of the mask body 1a to the outer peripheral side. It is preferable that it decreases continuously or stepwise as it goes. 4 and 5, the recess 15 is formed continuously or stepwise only in the central portion.

  In the present application, “the opening area ratio of the recess 15 per unit area in the region where the recess 15 is formed” is defined as a predetermined unit area in the central portion of the mask body 1a where the recess 15 is formed. The unit area P is defined as a ratio (Q / P) between the unit area P and the opening areas Q of the plurality of recesses 15 included in the unit area P. Therefore, even when the opening area ratio of the recess 15 is the same, the opening area ratio may be the same when a small number of recesses with a large opening area are formed and when many recesses with a small opening area are formed.

  In the first mode, as shown in FIG. 4, the opening area ratio of the recess 15 per unit area formed only in the central portion is continuously changed at a predetermined rate according to the distance from the center 6 of the mask body 1a. This is a mode that changes in a stepwise or stepwise manner. In this aspect, the opening area ratio of the recess 15 on or near the concentric circles having the same distance from the center 6 has the same value. The rate of change of the opening area ratio that changes according to the distance from the center 6 may be primary (primary expression) or secondary (secondary expression), and is not particularly limited. Since the shadow mask 1 having such a configuration has substantially the same structure in a concentric manner, the distribution is almost the same in a concentric manner in terms of strength. Therefore, the intensity balance of the shadow mask 1 becomes very regular, and the intensity of the shadow mask 1 can be gradually increased from the center toward the outer periphery.

  In the second mode, as shown in FIG. 5, the opening area ratio of the recess 15 per unit area formed only in the central portion is imaginary lines radially from the center 6 of the mask body 1a to the periphery of the mask body 1a. Are drawn to have the same value on a line connecting portions of the same proportion of the length of the virtual line. And the opening area ratio of the recessed part 15 per unit area in the area | region located between the outermost shell of the center part and the center 6 changes continuously or in steps with a predetermined change rate. In this aspect, the rate of change of the opening area ratio that changes from the center 6 toward the outermost shell may be either primary (primary expression) or secondary (secondary expression), and is not particularly limited. The shadow mask 1 having such an aspect has a very regular intensity balance, and the intensity of the shadow mask 1 can be gradually increased from the center of the shadow mask 1 toward the outer periphery.

  As a continuous or stepwise change in the opening area ratio of the recess 15 in the first aspect and the second aspect, for example, (1) make the opening area of each recess uniformly the same, and on the more central side The recess formation density may be increased to increase the opening area ratio of the recesses, and the recess formation density may be decreased to decrease the opening area ratio of the recesses as the distance from the center increases. (2) The formation density is the same, and on the more central side, the opening area of the recess is increased to increase the opening area ratio of the recess, and the opening area ratio of the recess is decreased and the opening area ratio of the recess is decreased as the distance from the center increases. May be. Moreover, methods other than these may be used and are not particularly limited.

  According to the first aspect and the second aspect, the partial weight of the shadow mask can be gradually reduced toward the central portion, so that the intensity balance of the shadow mask becomes extremely regular. As a result, even if stress such as impact is applied after the shadow mask is mounted on the cathode ray tube, the shadow mask is hardly deformed, and it is possible to more effectively prevent permanent dents from remaining.

  Next, a dot type shadow mask having a circular through hole for forming a circular beam spot on the phosphor will be described. FIG. 6 is a partial plan view and a partial cross-sectional view showing another example of the shadow mask of the present invention. 6A shows the planar shape and cross-sectional shape of the slot formed at the center of the shadow mask, and FIG. 6B shows the planar shape and cross-sectional shape of the slot formed on the outer periphery in the right direction on the horizontal axis of the shadow mask. The shape is shown.

  The shadow mask 20 shown in FIG. 6 has dots (20a, 20c) having a substantially circular through-hole 21 in which a back-side hole 23 on the electron gun side and a front-side hole 22 on the phosphor side communicate with each other. It is a shadow mask that is arranged in large numbers in the horizontal direction X and the vertical direction Y, and forms dot-shaped beam spots on the phosphor of the cathode ray tube. In the shadow mask 20 of the present invention, a large number of recesses 25 are formed in the central portion of the shadow mask surface on the electron gun side, as described above. Since the dot-type shadow mask 20 of this embodiment has the same technical features as the slot-type shadow mask, the description thereof is omitted, but each configuration is as described above. As shown in FIG. 6 (B), the shape of the front hole portion 22 is gradually flattened from a circular opening shape from the center to the outer peripheral portion so as not to block an unnecessary electron beam, It is formed so as to transition to an elliptical shape or an open-hole shape that approximates an elliptical shape.

  As described above, according to the shadow mask of the present invention, the center portion can be reduced in weight, and the center of gravity in the thickness direction at the center portion is shifted to the center side in the thickness direction. Since a large deformation based on the weight of the shadow mask hardly occurs due to an impact or vibration applied to the mask, it is possible to prevent a permanent dent from remaining in the central portion.

  In the shadow mask of the present invention, since many concave portions are formed on the electron gun side, the surface area is increased by the concave portions. As a result, it also has an effect of reducing the doming phenomenon (doming pattern, which is a phenomenon in which the shadow mask is deformed by heat generated by the electron beam and color unevenness occurs) when the electron beam is irradiated.

  Note that, as described in Patent Document 1, the shadow mask of the present invention has the long side far from the center of the mask main body 1a out of the two long sides forming the substantially rectangular through-hole 11. The present invention can also be applied to a shadow mask having a structure in which at least one end or both ends of the upper and lower ends of the side are bulged away from the vertical axis 4.

(Manufacturing method of shadow mask)
Next, an example of a method for manufacturing the shadow mask described above will be described. Needless to say, the shadow mask of the present invention is not limited to the following manufacturing method.

  The shadow mask can be formed by a conventionally known method. Usually, it is performed in each step of photo-etching and is manufactured by a continuous in-line apparatus. For example, a water-soluble colloidal photoresist or the like is applied to both surfaces of a metal thin plate and dried. After that, the photomask on which the shape pattern of the front side hole as described above is closely attached to the front surface, and the photomask on which the shape pattern of the back side hole and the concave portion is closely attached to the back surface, such as high pressure mercury Expose with UV light and develop with water. In addition, the positional relationship and the shape of the photomask in which the pattern of the front side hole part and the photomask in which the pattern of the back side hole part and the concave part are formed and the shape thereof are the front side hole part and the back side hole part formed in the obtained shadow mask, and It is designed and arranged in consideration of the positional relationship with the recesses and their sizes. The exposed portion of the metal, the periphery of which is covered with the resist film image, is formed in each shape as described above based on the difference in the etching progress speed of each portion. Etching is performed by spraying a ferric chloride solution from both sides after heat treatment or the like. Thereafter, the shadow mask according to the present invention is manufactured by continuously performing post-processes such as washing with water and peeling.

(Picture tube)
Next, the picture tube of the present invention will be described. FIG. 7 is a schematic sectional view showing an example of the picture tube of the present invention. A picture tube 101 according to the present invention includes the above-described shadow mask 1 according to the present invention, and includes a substantially rectangular front panel disposed on the front surface and a funnel-shaped funnel connected to the front panel. It consists of a vacuum tube. In such a picture tube 101, an electron gun 103 provided at the neck portion of the funnel has three types of electron beams 105 for causing the phosphors 102 of the three primary colors (R, G, B) applied on the inner surface of the front panel to emit light. Release.

  The shadow mask 1 of the present invention is provided on the inner surface of the front panel so as to face the phosphor 102 with a slight gap. The shadow mask 1 has dot holes or slot holes regularly arranged so as to pass the electron beam 105 from the electron gun 103 and hit a predetermined phosphor 102. The three types of electron beams 105 emitted from the electron gun 103 are scanned horizontally and vertically by the magnetic field generated by the deflection yoke 104, pass through the shadow mask 1, and land at a predetermined position of the phosphor 102. Is emitted to form an image.

  The shadow mask 1 of the present invention is preferably applied to a picture tube having a large viewing angle of 21 inches or more. However, the shadow mask 1 may be used for a conventional picture tube whose viewing angle is not so large, and is permanent even by a drop impact or the like. There is an advantage that a dent hardly remains.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples.

Example 1
A shadow mask 1 for a 32-inch cathode ray tube made of an Fe—Ni alloy having a thickness of 0.22 mm was manufactured by the general shadow mask manufacturing method described above. This shadow mask is a slot-type shadow mask that forms a rectangular beam spot on the phosphor screen of a cathode ray tube. The through hole 11 has a horizontal width X of 185 μm and a vertical direction Y of 470 μm. The pitch in the horizontal direction X was 0.70 mm. Further, the width W1 in the horizontal direction X of the front side hole 12 at the center portion is 400 μm, the width in the vertical direction Y is 540 μm, the width W2 in the horizontal direction X of the front side hole 12 at the outer peripheral portion is 580 μm, and the width in the vertical direction Y Was 520 μm.

  A circular recess 15 was formed on the surface of the shadow mask on the electron gun side by half etching. The concave portion 15 has its diameter L and depth d changed radially as shown in FIG. The pitch of the recesses 15 was 0.15 mm, and three rows of recesses were formed between the slots in the form of FIG. The diameter L and depth d of the recess 15 are 130 μm in diameter and 75 μm in depth at the center 6, and are 40 μm in diameter and 20 μm in depth from the center 6 to a radius of 150 mm. Changed. In addition, the recessed part 15 was not formed except within the range of radius 150mm from the center. FIG. 8 is an enlarged photograph of the central portion of the obtained shadow mask as viewed from the side on which the electron beam is incident.

  About the obtained shadow mask, the cross-sectional photograph of the center 6 portion was compared with the cross-sectional photograph of the portion entering the center side 30 mm from the outer peripheral edge on the horizontal axis, and the weight reduction was evaluated by comparing the cross-sectional areas. . As a result, it was possible to reduce the converted weight at the central portion within the range of 12 to 15% rather than the converted weight at the outer peripheral portion. Further, the center of gravity in the thickness direction at the center was converted to the position of 60 to 65 from the surface on the electron gun side when the thickness T of the shadow mask was 100. When this shadow mask was attached to a 32-inch flat cathode ray tube, and then impact loads of 10G, 11G, and 12G were sequentially applied to the cathode ray tube by the following drop impact test, in either case, the shadow attached in the cathode ray tube was applied. There was no permanent dent in the mask.

(Example 2)
A shadow mask of Example 2 was produced in the same manner as in Example 1 except that the shape of the concave portion was changed from a circular shape to a substantially square shape with a side of 100 μm in Example 1. Specifically, the length L and the depth d of one side of the substantially square recess 15 are changed radially as shown in FIG. The pitch of the recesses 15 was 0.15 mm, and three rows of recesses were formed between the slots in the form of FIG. The size L and the side length d of the recess 15 are 100 μm and a depth of 75 μm at the center 6, and the length of one side at a radius of 70 mm from the center 6 is 30 μm and the depth of 20 μm. The depth was changed secondarily. Note that, as in Example 1, the recess 15 was not formed except within a radius of 70 mm from the center.

  About the shadow mask obtained in this way, the cross-sectional photograph of the center 6 part is compared with the cross-sectional photograph of the part entering the center side 30 mm from the outer periphery on the horizontal axis, and the weight reduction is evaluated by comparing the cross-sectional areas. did. As a result, it was possible to reduce the converted weight at the center portion within the range of 5 to 15% rather than the converted weight at the outer peripheral portion. Further, the center of gravity in the thickness direction at the center was converted to the position of 60 to 65 from the surface on the electron gun side when the thickness T of the shadow mask was 100. When this shadow mask was attached to a 32-inch flat cathode ray tube, and then impact loads of 10G, 11G, and 12G were sequentially applied to the cathode ray tube by the following drop impact test, in either case, the shadow attached in the cathode ray tube was applied. There was no permanent dent in the mask.

(Comparative Example 1)
In Example 1, a shadow mask of Comparative Example 1 was produced in the same manner as in Example 1 except that no recess was formed.

  About the shadow mask obtained in this way, the cross-sectional photograph of the center 6 part is compared with the cross-sectional photograph of the part entering the center side 30 mm from the outer periphery on the horizontal axis, and the weight reduction is evaluated by comparing the cross-sectional areas. did. As a result, the converted weight of the outer peripheral portion and the converted weight of the central portion were almost the same. Further, the center of gravity in the thickness direction at the center was converted to a position of 65 to 70 from the surface on the electron gun side when the thickness T of the shadow mask was 100. When this shadow mask was mounted on a 32-inch flat cathode ray tube, and then impact loads of 10G and 11G were sequentially applied to the cathode ray tube by the following drop impact test, the shadow mask mounted in the cathode ray tube was permanent at 11G. A dent was seen.

(Drop impact test)
FIG. 9 is a schematic diagram of a drop impact test method. In the drop impact test, as shown in FIG. 9, a color cathode ray tube 101 equipped with a shadow mask is attached to a metal frame 110 with the electron gun side down, and is naturally dropped onto a drop table 111 from a predetermined height. Do it. The height is set by the acceleration tester installed on the drop table 111 so as to have a predetermined acceleration as described above. After the drop impact test, the cathode ray tube subjected to the test is made to emit light, and the color uniformity is observed from the front surface of the cathode ray tube to confirm whether or not the shadow mask has a permanent dent.

It is the fragmentary top view and fragmentary sectional view which show an example of the shadow mask of this invention. It is a top view which shows an example when the center part of the shadow mask of this invention is seen from the side from which an electron beam radiate | emits. It is a top view which shows an example when the center part of the shadow mask of this invention is seen from the side into which an electron beam injects. It is a typical front view explaining an example of the aspect which changed the opening area ratio of the recessed part of the shadow mask continuously or in steps. It is a typical front view explaining another example of the aspect which changed the opening area ratio of the recessed part of the shadow mask continuously or in steps. It is the fragmentary top view and fragmentary sectional view which show another example of the shadow mask of this invention. It is sectional drawing which shows an example of schematic structure of a thin color cathode-ray tube. It is an enlarged photograph when the central part of the shadow mask obtained in Example 1 is seen from the side on which the electron beam is incident. It is the schematic of a drop impact test method. It is a typical top view which shows an example of the shadow mask with which a thin color cathode ray tube is provided. It is a typical top view which shows the shape of the slot formed in each part of a mask main body. It is sectional drawing which shows the form with which the dent remained in the center part of the shadow mask with which the thin color cathode-ray tube was mounted | worn. It is explanatory drawing of the phenomenon when an impact is applied to the cathode ray tube or TV set provided with the shadow mask.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Shadow mask 1a Mask main body 1b Skirt part 2,2a, 2b, 2c, 2d Slot 3 Horizontal axis 4 Vertical axis 5 Diagonal axis 6 Center part (center)
7 Electron beam 11, 21 Through hole 12, 22 Front side hole 13, 23 Back side hole 14, 24 Ridge line part 15, 15 a, 15 b, 25 Recessed part 101 Braun tube (picture tube)
DESCRIPTION OF SYMBOLS 102 Fluorescent substance 103 Electron gun 104 Deflection yoke 105 Electron beam 110 Drop test frame 111 Drop test drop base 121 Substantially elliptical dent 122 Vertical wave extending in the vertical direction 123 Vertical wave flowing in the horizontal direction X Horizontal direction Y Vertical direction W1 Horizontal width of the front hole in the center portion W2 Horizontal width of the front hole in the left and right sides d Depth depth L Depth width or diameter T Shadow mask thickness θ Incident angle of electron beam

Claims (6)

  A large number of through holes in which the back side hole part on the electron beam incident side and the front side hole part on the electron beam emission side communicate with each other are arranged in the horizontal direction and the vertical direction of the mask body, on the phosphor of the cathode ray tube. A shadow mask for forming a beam spot having a predetermined shape, wherein a plurality of recesses are formed at least in a central portion of the shadow mask surface on which the electron beam is incident.   The shadow mask according to claim 1, wherein the concave portion is formed only in a central portion of the mask main body.   The opening area ratio of the concave portion per unit area in the region where the concave portion is formed decreases continuously or stepwise from the center of the mask body toward the outer peripheral side. 2. The shadow mask according to 2.   The shadow mask according to claim 1, wherein the recess is one or more half-etched holes selected from a circle, a rectangle, and a polygon.   The horizontal width of the front side hole formed in the central portion of the mask body is smaller than the horizontal width of the front side hole formed on the left and right sides of the mask main body. The shadow mask according to any one of the above. 6. A picture tube comprising the shadow mask according to claim 1.

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