CZ284014B6 - Color picture tube with enhanced holder of a screen mask frame - Google Patents

Abstract

The shielding mask (24) comprises a perforated portion (25) whose openings are centered with the phosphor elements on the screen (22). The connecting means (34) are formed by a mandrel (44) attached to the glass envelope (10), a spring (46) having an opening (60) therein for engagement on the mandrel (44), and a plate (48) welded between the spring (46) ) and mask and frame system. The spring (46) and the plate (48) are mechanically coupled to the protrusions that connect them to each other at two spaced locations (50, 51). ŕ

Description

(57)

The screen mask (24) of the screen comprises a perforated portion (25) whose apertures are centered with phosphor elements on the screen (22). The attachment means (34) is formed by a mandrel (44) attached to the glass envelope (10), a spring (46) having an aperture (60) therein for engaging the mandrel (44), and a plate (48) welded between the spring (46). ) and the mask and frame assembly. The spring (46) and the plate (48) are mechanically coupled to the protrusions that connect them to each other at two separate locations (50, 51).

Color screen with improved shadow mask frame holder

Technical field

BACKGROUND OF THE INVENTION The present invention relates to color screens of the type having a screen mask attached to a peripheral frame that is suspended relative to a cathodoluminescent screen comprising blue-emitting, green-emitting and red-emitting phosphor elements, and more particularly to improved means for securing the frame and mask assembly therein. in which the electron beams generated by the electron gun would hit the correct phosphorus elements.

BACKGROUND OF THE INVENTION

In most types of color screens, the peripheral frame holding the screen mask is hung on the front panel by means of resilient elements which are either welded directly to the shop or to the plates which are in turn welded to the frame. In the directly welded version, the elastic elements are usually made of bimetallic materials and in the plate version the plates are bimetallic. Once the resilient members or plates are heated by heat transfer from the mask through the frame, the bimetallic materials expand differently and thereby bend the resilient members or plates, causing the mask frame assembly to move toward the screen provided on the panel. It is also known to use a geometric design of elastic elements which causes the same movement towards the screen by the force of the expanding mask frame assembly against the elastic elements.

It is common to use either three or four resilient members to hold the mask and frame assembly in the rectangular faceplate of the screen. In a system using three resilient elements, one is usually located at the top in the center of the mask and the other two are located along the sides of the screen between the center of the sides of the mask and the lower two corners of the mask. In a system using four resilient elements, these elements are typically located at the top and bottom centers of the mask and at the left and right centers of the mask. In both the three-element and four-element systems as described above, it is possible for the mask-frame assembly to slightly twist and move relative to the faceplate during manufacture and / or operation. Known means for minimizing twisting and displacement of the mask and frame assembly utilize resilient grip at four corners of the frame.

A problem with the above-described structures for the plate version is that it is difficult to nondestructively assess the quality of the welds used to attach the resilient members to the plates and the plates to the frame. Defective welds can break due to thermal or mechanical shock and the welding itself can form scales, i.e. metal particles expelled from the welding area due to improper contact between the parts to be joined and the welding electrodes. Scale particles can disperse in the sealed screen and cause either cosmetic or electrical problems. Another welding-related problem arises when the joining parts are not aligned with each other and a lump-like weld is formed between the parts which can act as a pivot point and can cause a weld defect or relative rotation of the parts and the shield mask under shock load. This results in the centering of the apertures in the screen mask and the phosphor elements of the cathodoluminescent screen, and thus the impact of the electron beams on the regions of the screen other than intended.

SUMMARY OF THE INVENTION

The improved color screen of the invention includes an evacuated glass envelope having a faceplate on which a cathodoluminescent screen is mounted. The panel includes a color selection electrode assembly that is connected thereto by attachment means disposed around the periphery of the panel. Each attachment means comprises a tm coupled to a glass envelope, a spring having a dark engagement opening therein, and a plate welded between the spring and the selection electrode assembly.

- 1 GB 284014 Β6 colors. The improvement consists in mechanically attaching the spring and the plate to the protrusions connecting each other at two spaced locations along one edge of the parts. In exemplary embodiments of the solution, the faceplate is rectangular and circumferentially spaced locations of the retaining means are arranged either along opposite sides of the faceplate or at the corners of the faceplate. In a further exemplary embodiment of the present invention, the board 1 of the frame is mechanically connected by protrusions interconnecting the board and the frame at two spaced points. These spaced points are arranged along a second edge of the plate opposite the first edge attached to the spring.

BRIEF DESCRIPTION OF THE DRAWINGS

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described in more detail with reference to the accompanying drawings, in which: Figure 1 is a side axial section of a color screen according to the invention; Figure 2 is a schematic rear view of a faceplate carrying a mask mask assembly; Fig. 4 is a side sectional view taken along lines 4-4 of Fig. 3 showing details of interconnected protrusions of the retaining means; Fig. 5 is a schematic rear view of Figs. Fig. 6 is a partial cross-sectional view of the panel and shielding mask assembly of Fig. 5, and Fig. 7 is a cross-sectional view taken along lines 7-7 of Fig. 5 showing a corner attachment; means.

DETAILED DESCRIPTION OF THE INVENTION

Figure 1 shows a rectangular color screen 8 having a glass envelope 10 comprising a rectangular faceplate 12 and a cylindrical neck 14 connected by a rectangular sticker 16. The faceplate 12 includes an observation faceplate 18 and a peripheral flange or sidewall 20 that is fused to the funnel 16 The front panel 12 has two rectangular axes: a major axis XX parallel to the longer dimension, which is generally a horizontal dimension, and a minor axis YY, parallel to its shorter dimension, which is usually vertical. The major and minor axes are perpendicular to the central longitudinal axis of the ZZ screen, which extends through the center of the neck 14 and the center of the panel 12. A three-color phosphor screen 22 consisting of blue, green and red color emitting phosphor elements is disposed on the inner face The screen is preferably a line screen with phosphor lines extending in the base parallel to the two side YYs. Alternatively, the screen may be a point screen. The multi-hole color selection electrode or shield mask 24 is removably attached by improved means in a predetermined spatial relationship to the shield 22. The electron gun 26 is centrally mounted in the throat 14 to form three electron beams and direct them along the convergent paths through the apertures in the curved aperture 25 to shade 22.

The screen of Figure 1 is designed for use with an external magnetic deflection yoke, such as yoke 28 located adjacent to the connected funnel 16 and throat 14. When activated, the yoke 28 supports three electron beams to magnetic fields that cause the beams to scan horizontally and vertically. forming a rectangular grid on the screen 22.

The shield mask 24 is part of a mask and frame assembly 30 that also includes a shield mask peripheral frame 32. The mask and frame assembly 30 is positioned in the front panel 12 in the embodiment shown in Figures 1 and 2. The mask and frame assembly 30 is secured to the panel 12 by four improved fastening means 34 shown in Figures 2, 3 and 4.

The shield mask 24 comprises a curved, apertured portion 25, an unbored edge portion 27 surrounding the apertured portion 25, and a flange portion 29 bent back from the edge portion 27, and

The flare portion 29 of the mask 24 is inserted inside or housed in the frame 32 and welded to its inner surface.

The attachment means 34 are located at circumferentially spaced locations of the mask and frame assembly and panel 12. Each attachment means 34 includes tm 44, springs 46 and plate 48. Each tm 44 is a conical metal member that is connected to the side wall 20 of the panel, for example, along the major and minor axes of the 29V screen, whose diagonal is 66 cm. The aperture 60 in the spring 46 is coupled to the free end of darkness 44. The plate 48 is a bimetallic element comprising a first metal layer 48a and a second metal layer 48b which are adjacent to each other by their faces and joined together by lamination or otherwise. The spring 46 is in contact with and attached to the first metal layer 48a of the plate 48, while the second metal layer 48b is attached to the frame 32. The bimetallic materials of the plate 48 are selected such that when heated the plate 48 moves toward the frame 32 and moves the assembly. Thus, the thermal expansion coefficient of the metal layer 48b of the frame 32 must be less than the expansion coefficient of the layer 48a attached to the spring 46. This thermal compensation design is discussed in U.S. Patent No. 3,803,436 issued to Morrell 9. April 1974.

In contrast to the prior art, the spring 46 is not attached to the plate 48 by welding, but by mechanically connecting the components using protrusions that interconnect the components along faces facing each other. The protrusions are formed at two spaced apart locations 50 and 51 along the edge 52 of the parts to be joined. The cross-section of the interlocking protrusions is shown in FIG. 4. In this exemplary embodiment, the centers of the protrusions are about 19.05 mm apart and about 4.78 mm apart from the edge 52 of the parts to be joined. The other end of the plate 48 is secured to the frame 32 by conventional welding or by using protrusions of the type described. The attachment points 53, 54 shown in FIG. 3 are located about 25.4 mm apart and 4.78 mm from the opposite edge 55 of the plate 48. The lateral spacing A between the attachment points 50, 51 and the points 53, 54 is about 22.2 mm for providing adequate space for movement of the plate 48 to achieve temperature compensation.

The interconnecting protrusions at locations 50, 51 may be formed using conventional bending devices as available from Tech-Line Engineering Co. of Warren, Michigan or BTM Corp. of Marysville. Michigan.

The advantages of interconnecting protrusions over conventional attachments of means such as welding or riveting are the elimination of welding scales, the possibility of non-destructively detecting the quality of the joints, the high degree of accuracy of joint placement, the elimination of pre-forming rivet holes. A drawback of the interconnecting protrusions is that their strength is only about 70% of the weld strength at an equivalent lump dimension. However, by slightly increasing the lump dimension of the protuberance, a comparable bond strength can be achieved.

An unexpected advantage of the interconnecting protrusions is an improvement in the shock and static load test for a panel having a shield mask assembly mounted and using new interconnecting protrusions to connect the associated springs 46 and plates 48. The shock tests were performed on twelve assembled panels manufactured with interconnecting protrusions at locations 50 and 51. The test systems were compared to eight conventional inspection assembled panels in which the springs were welded to the plates. Both the test and control systems had plates welded to the shield mask system frame.

The panels were prepared using conventional matrix procedures as described in U.S. Patent No. 4,049,452 issued to Nekut on September 20, 1977. A photoresist solution whose solubility changes when exposed to light was applied to the inner surface of the panel and dried . A shadow mask assembly was placed in the panel and light from the beacon was projected through the mask openings to expose selected areas of the photoresistor. In this case, the beacon directed the light at an angle identical to the angle at which the electron beams hit the green color emitting phosphorus.

-3 CZ 284014 B6

The mask assembly was removed from the panel and the unexposed, more soluble parts of the photoresistor were removed by washing. A light absorbing matrix material solution was then applied to the bare areas of the panel and to the areas where the exposed photoresist was retained. The matrix solution was dried and then etched with a suitable etch that softened and removed the lower entrapped regions of the photoresistor and the overlapping matrix material, leaving the light absorbing matrix material on most of the panel with clear windows formed at previously occupied lower photoresist layer and overlaying matrix material. .

The windows in the matrix allow measurement of the shift of the scoring. When the shadow mask assembly is reinserted into the panel with the windows formed as described above, light from the exposure beacon passes through the open windows, and the location of the light can be accurately read using an instrument called a matrix scan reader. The panels were then subjected to a shock drop test to provide a 35G panel shock with a shield mask system attached thereto. G is the gravitational force. The panel assemblies were shocked with the panel in the normal viewing orientation, designated as Y in Table 1, with the panel face down, designated FD, and also with the face panel up, designated FU. Separate panels were used for each test. Prior to the shock test, the panel assemblies were thermally cycled by passing a stabilizing furnace at a temperature of 450 ± 15 ° C. Thermal stress cycling was repeated five times for each panel to ensure the worst case condition. The results of the drop test are recorded in Table 1. C denotes a control screen having normally welded springs and a plate, and T denotes a test screen having a spring and a plate interconnected by the protrusions shown in Figures 3 and 4. Shift displacement was measured at seven locations for each panel assembly. In the center (CTR), on each diagonal about 25 mm from the screen edge (2D. 8D, 4D and 10D), on the major axes (3:00 and 9:00). Measurements were made by projecting light from the same beacon that was used to create windows in the matrix through the mask assembly and its windows by measuring the amount of displacement or non-coverage due to a 35G shock. The recorded values are in micrometers (μ), the smaller the absolute displacement value, the smaller the displacement offset. The + and - markings refer to the shift in one direction or the other.

Table 1

Change after 35G shock test

CTR 2D 3:00 4D 8D 9:00 10D C2 Y 1 7 4 3 2 -4 -5 C3 Y 2 8 8 10 0 -4 -4 Diameter = Y 1 7 6 6 1 -4 -4 C4 FU 1 11 13 12 -12 -12 -11 C5 FU 4 25 21 23 -6 -10 -16 C6 FU 1 16 13 13 -6 -8 -11 Diameter = FU 2 17 16 16 -8 -10 -12 C7 FD 2 -27 -23 -19 29 34 35 C9 FD 4 -20 -15 -13 29 34 29 C10 FD 1 -24 -24 -31 31 30 30 Diameter = FD 2 -23 -21 -21 30 32 31 TI Y 2 2 0 1 6 1 -2 T2 Y 6 3 4 9 4 1 T3 Y -1 3 2 -1 3 1 -2 Diameter = Y 1 3 2 1 6 2 -1

-4GB 284014 B6

Table 1 - continued

Change after 35G shock test

CTR 2D 3:00 4D 8D 9:00 10D T4 FU -1 13 9 7 -12 -16 -18 T5 FU 3 13 13 15 Dec -14 -14 -13 T6 FU 2 12 9 8 -8 -13 -13 T7 FU 1 11 9 11 -11 -12 -14 Diameter = FU 1 12 10 10 -11 -13 -14 T8 FD -2 -28 -36 -40 28 26 18 T9 FD -2 -36 -40 -45 35 29 19 Dec T10 FD 1 -30 -24 -22 21 29 29 Til FD 1 -22 -28 -29 25 24 25 T12 FD 2 -21 -25 -26 27 Mar: 27 Mar: 23 Diameter = FD 0 -27 -31 -32 27 Mar: 27 Mar: 22nd

Comparison of the displacement shifts of the drop test and test panels with the array of panels in the normal viewing orientation (Y) reveals that in the center, the test and control panels have the same amount of coverage. However, at 2D, 3:00, 4D, 9:00, and 10D, the absolute overlap of the test panels was two to five microns smaller, while at 8D, the diameter of the test panel was 5 microns more overlapped than the control panels. On average, after the Y-shock shock test, the panels tested showed less overall coverage than the control panels. In the upside position, the drop test results were also in favor of the panels tested, with less center and 3D, 3D, and 4D overlap, but with slightly greater overlap than the control panels at 8D, 9:00, and 10D. In the FD test, the panels tested were worse than the control panels, but the results were poor for both types.

The results of the static load tests on two possible control screens made with conventional welds and two test screens where the springs were fixed to the plates using new interconnecting protrusions are entered in Tables 2 and 3 respectively.

Table 2

Sample C1

LBS p2D 2D 3:00 4D 8D 9:00 10D 0 0 0 0 0 0 0 5 -1 1 1 2 1 0 10 0 0 1 3 1 0 15 Dec _2 0 1 1 1 1 20 May -3 0 -3 0 2 -1 25 -4 0 -3 1 2 -1 30 -8 -1 -2 -4 2 -4 35 -10 0 -3 0 0 -7 40 -17 -1 1 0 -1 -11 45 -27 2 4 -2 -18 50 -37 -8 9 8 -2 -31 55 -47 -9 16 16 0 -35

-5GB 284014 B6

Sample C12

p2D 2D 3:00 4D 8D 9:00 10D 0 0 0 0 0 0 0 5 1 0 -2 0 0 0 10 0 -2 -3 -1 -2 1 15 Dec 0 0 -2 -1 -2 0 20 May -5 -1 -4 -2 -2 -3 25 -7 -1 -4 -2 -2 -2 30 -9 _2 -4 -2 -3 -3 35 -9 _2 -4 -2 -2 -8 40 -15 -3 -2 0 -2 -12 45 -25 -7 0 3 -5 -20 50 -35 -9 4 7 -6 -27 55 -49 -13 17 17 -6 -40

Table 3

Sample TI3

LBS p2D 2D 3:00 4D 8D 9:00 10D 0 0 0 0 0 0 0 5 -2 1 2 1 2 3 10 _2 1 0 0 2 6 15 Dec -3 2 3 2 2 5 20 May -7 0 0 -1 3 5 25 -11 _2 -1 -2 2 2 30 -15 -4 -3 -3 1 3 35 -21 -6 -6 -4 -2 -1 40 -6 -7 -5 -3 -4 45 -27 -6 -3 -2 -3 -9 50 -34 -6 0 1 -4 -13 55 -43 -8 3 3 -2 -19

Sample T14

p2D 2D 3:00 4D 8D 9:00 10D 0 0 0 0 0 0 0 5 6 8 10 7 5 4 10 5 4 7 8 5 6 15 Dec 2 5 7 8 5 6 20 May 0 4 7 10 6 7 25 1 7 7 5 4 30 -4 2 7 7 5 5 35 -10 0 5 6 3 2 40 -15 -1 6 8 4 0 45 -19 -1 6 9 3 -4 50 -23 -1 11 12 4 -8 55 -37 16 17 3 -13

-6GB 284014 B6

In the static load test, it was pushed against the corner of the frame against the 2D corner (hour hand in position 2) and the displacement of the light source through the matrix holes was recorded in the corners (2D, 4D, 8D and 10D) and on the main axis (3:00) and 9:00). All readings were made about 25 mm from the edge of the screen. The compression force increased in increments of 2.268 kg and the respective shifts were recorded. The plates and springs of the test screens T13 and T14 were mechanically connected by new protrusions that interconnected the parts. The plates and springs of the control screens C11 and C12 were joined by conventional welding. The panels of both test and control screens were welded to the shield mask frame as described above for the shock test screens. The interconnected plates and springs of the test screens T13 and T14 exhibited greater resistance to displacement or non-coverage than the welds of the control screens. This is based on a comparison of the maximum displacement at the non-contacted corner 10D, where the static load is increased from 40 to 55 pounds at the 2D corner. A 45 pound test load simulates the forces exerted on the mask-frame assembly if the panel with the mask-frame assembly mounted is handled incorrectly during manufacture and pressure is applied to the mask-frame.

Concerning Table 2, when a 40 pound load was applied to the corner of the 2D control screens, the greatest displacement at the uncontrolled corner occurred at the corner of the 10D control screens where the non-coverage was 11 and 12 microns, respectively. However, as shown in Table 3, for the test screens, an equivalent 40 pound load at the 2D corner resulted in a 4 or 0 micron shift in the 10D corner, respectively. When the load in the 2D corner was increased to 55 pounds, the corresponding displacements in the 10D corner for the control screens were 35 and 40 microns, as shown in Table 2, while the displacements for the test screens were only 19 and 13 microns, respectively, as shown in the table. 3.

Although the invention has been described with respect to fasteners located on the major and minor axes of the shield mask and frame and panel assembly, the retaining means may also be located at other locations of the panel and mask and frame assembly. As shown in Figures 5, 6 and 7, the retaining means 34 'are arranged on each of the four kinds of mask and frame and panel 12 panel 30. Parts that are similar to those in Figures 1 to 4 are identified by the same numeral. Each retaining means 34 'includes a tm 44'. spring 46 'and plate 48'. Each plate 48 'is welded near one end of the truncated corner of the frame 32'. The connection may be a normal weld or a pair of new protrusions at points 53 'and 54' may be used to connect frame 32 'and plates 48' to each other. The spring 46 'is secured by one of its ends to the other end of the plate 48' by protrusions at locations 50 'and 5' which connect the parts to each other as shown in Figure 4 for the first exemplary embodiment. Spring 46 'includes an opening 60' near its free end, and this is engaged with the conical portion of darkness 44 '.

The plate 48 'has a laminate bimetallic structure as shown in Fig. 6. One metal layer 48a' facing the frame 32 'is made of a material with high thermal expansion and the other metal layer 48b'. facing the spring 46 '. is made of a material with low thermal expansion. Both the spring 46 and the plate 48 contribute to the compensation necessary to move the mask and frame assembly 30 toward the screen to compensate for the thermal expansion of the mask 24 during operation of the screen. The extent of spring and plate contributions is described in US Patent No. 5,063,325 issued to Raglandoji, Jr. on Nov. 5, 1991.

Claims (5)

PATENT CLAIMS A color screen comprising an evacuated glass envelope having a faceplate on the inner surface of which a cathodoluminescent screen is disposed, a color selection electrode assembly disposed spatially with respect to the screen and connected to the panel by attachment means disposed around the perimeter of the panel, the means comprising a tm coupled to the panel, a spring and a plate, the spring being fixed to the plate and having a hole for receiving darkness, and the plate is fixed to the frame, characterized in that the spring (46, 46 ') and the plate (48, 48') 2, the protrusions are mechanically interconnected at two spaced apart locations (50, 51, 50 ', 5Γ) along one edge (52, 52') of the spring (46, 46 ') and the plate (48, 48'). Screen according to claim 1, characterized in that the front panel (12) is rectangular and the circumferentially spaced locations (50, 51) of the holding means (34) are arranged along opposing sides of the front panel (12). Screen according to claim 1, characterized in that the front panel (12 ') is rectangular and the circumferentially spaced locations (50', 5 ') of the retaining means are arranged at the corners of said front panel (12'). Screen according to claim 1, characterized in that the plate (48, 48 ') is mechanically connected to the frame (32, 32') by protrusions interconnecting the plate (48, 48 ') and the frame (32, 32') in two spaced apart points (53, 54, 53 ', 54'). Screen according to Claim 4, characterized in that the spaced points (53, 54, 53 ', 54') are spaced along the second edge (55, 55 ') of the plate (48, 48') opposite the first edge (55, 55 '). 52, 52 ') connected to the spring (46, 46').