KR20010040222A - Shadow mask assembly for use in a color crt - Google Patents

Abstract

PURPOSE: To provide a color cathode-ray tube that causes vibrations of the shadow mask to be prevented or decayed by making a vibration-proof means surely contact with the mask without generating shadows. CONSTITUTION: In a color cathode-ray tube that bridges a shadow mask 2 having slot-shaped (or dot-shaped) electron beam passing holes 3, grill parts 4 that extend in the direction at right angles to horizontal scanning direction of the electron beam and bridge parts connecting adjacent grill parts 4 on a pair of mask flames 28a and 28b in the direction of extending grills, damper lines 6 are laid extending in superposition with the outermost grill parts 4a of the shadow mask 2.

Description

SHADOW MASK ASSEMBLY FOR USE IN A COLOR CRT}

The present invention relates to a shadow mask assembly for use in a color CRT (cathode ray tube), and more particularly, to a shadow mask assembly having a damper for preventing or suppressing vibration of a slotted shadow mask fixed on a mask frame.

Color CRTs are generally used as display devices in computer systems or as TV receivers. 1 shows a color CRT suitable for use in a high resolution TV receiver. This color CRT comprises a bulb 25 formed by integrally joining the front panel 22 and the funnel 23 by a fleet glass 24. Coating on the inner surface of the front panel 22 forms a fluorescent screen 26, which includes a plurality of fluorescent dots or stripes that emit green, blue, and red light. The shadow mask assembly 29 is disposed behind the fluorescent screen 26 with a predetermined distance between the inner surface of the fluorescent screen 26. The shadow mask assembly 29 includes a mask frame 28 and a shadow mask 27 fixed by welding on the mask frame 28. The shadow mask assembly 29 has a front face by inserting stud pins 33 extending from the front panel 22 into hook springs 32 attached on the sidewall of the mask frame 28. It is fixed on the panel 22. An electron gun 31 which emits three electron beams is arranged in the neck 30 of the funnel 23. A deflection yoke assembly 32 is also disposed outside the cone of the funnel 23 in front of the electron gun 31.

In the above-described color CRT 21, three electron beams R, G, and B emitted by the electron gun 31 are deflected in the horizontal and vertical directions by the deflection yoke assembly 32, and the color by the shadow mask 27. Is selected according to, and hits a particular fluorescent film of fluorescent screen 26, which emits light for display of a color image.

Examples of representative shadow mask assemblies include an aperture grill type as disclosed in JP-A-6-314547. FIG. 2 shows the aperture grille shadow mask assembly disclosed therein, wherein both edges of the aperture grille mask 27a are welded to a pair of frame bars 28a, 28b of the mask frame 28. It is fixed on the phase. The pair of frame legs 28c, 28d of the mask frame for fixing the frame bars 28a, 28b are made of an elastic member. During the manufacturing process, the upper and lower ends of the shadow mask 27a are subjected to an external force that compresses the distance between the frame bars 28a and 28b by a certain amount using the elastic deformation of the frame legs 28c and 28d simultaneously with welding. It is fixed on the frame bars 28a and 28b by applying it. After welding, the external force is removed to provide external tension in the y direction to the shadow mask 27a. A plurality of damper wires 35 are stretched on the grid elements 34 so that the damper wires 35 intersect with the grid elements 34 to prevent or suppress the vibration of the shadow mask 27a.

In a color CRT with an aperture grill mask assembly as described above, because the damper wires extend across a slot or opening through which the electron beam passes, the electron beams scanned in the x direction impinge on the damper wires 35 and Therefore, the amount of electrons impinging on the fluorescent film is reduced. This reduces the luminance of the fluorescent film and creates shadows of the damper wires, thereby degrading the picture quality of the CRT.

JP-A-8-227667 discloses a shadow mask assembly as shown in FIG. 3 to solve the above problem. The slotted mask 27b has a plurality of apertures 36 arranged in a plurality of columns in the y direction, and a plurality of grill sections (grills) 37 each extending in the y direction between two of the aperture columns. And a plurality of bridge sections (bridges) 38 each connecting adjacent grilles 37 while passing between the apertures 36.

Opposite ends of the slotted mask 27 are fixed on the pair of frame bars 28a and 28b by external force simultaneously with welding. In this technique, since a plurality of damper wires 40 extend on each grill section 37, no shadow of the damper wire 40 occurs.

In the shadow mask assembly shown in FIG. 3, the effect for the prevention or suppression of vibration of the shadow mask is generally limited. After examining the structure, the inventors found that the cause of the insufficient effect is due to insufficient contact between the damper wire and the shadow mask, as will be described later with reference to FIGS. 4A and 4B. 4A and 4B show partial detailed top views of the shadow mask of FIG. 3 and cross-sectional views cut along the line IV-IV in FIG. 4A, respectively.

As shown in FIG. 4B, the middle portion or aperture region of the shadow mask 27b between the two frame bars 28a, 28b is disposed on the two frame bars 28a, 28b shown by the dashed line "P". It is slightly depressed rearward with respect to both ends of the shadow mask 27b. This results in a non-contact state between the damper wires 40 and the surface of the aperture area of the shadow mask 27b, reducing the effect of the damping function of the damper wire 40. The depression of the aperture area of the shadow mask is thought to be due to the following fact.

The grilles 37 of the slotted shadow mask 27a are connected in the transverse direction (x direction) by the bridges 38. In this case, when the external tension is applied in the y direction to the shadow mask 17a, external tension is applied. Is transmitted in the x direction due to the presence of the bridge 28. Thus, the shadow mask 27a is pressed backward in the aperture area, since the shadow mask has a bend in the x direction as shown in Fig. 4b, The depression of the shadow mask is increased, in which case the smaller the curvature of the frame bars 28a, 28b, the greater the depression occurs.The depression results in a non-contact state between the damper wire 40 and the shadow mask 27b. The damping function of the damper wire 40 is reduced, which in turn degrades the arrival of the electron beams on the fluorescent screen and degrades the purity of the color, thus degrading the picture quality of the CRT.

In view of the above problems in the prior art, an object of the present invention is to provide a shadow mask for use in a color CRT, including a plurality of apertures arranged in a plurality of columns, extending between each two columns of the aperture columns. A shadow mask having a grill, and a plurality of bridges, each connecting two of the grilles, each at the back of the shadow mask such that the shadow mask is externally tensioned with the shape of a portion of a substantially cylindrical surface; A mask frame comprising a pair of frame bars having a curved front to support the ends of the shadow mask, and the shadow mask extending on the front surface of the shadow mask and on the outermost grille of the grilles, respectively Mask used in a color CRT comprising a pair of first damper members pushing the back toward its back side To provide for.

According to the shadow mask assembly of the present invention, a damper member on the outermost grille pushes an end of the shadow mask, which can be bent toward the front of the shadow mask, thereby effectively bringing the damper member into close contact with the shadow mask. . This improves the damping function of the damper member and improves the image quality of the CRT having the shadow mask.

The above and other objects, features and advantages of the present invention will become more apparent from the following description with reference to the accompanying drawings.

1 is a cross-sectional view of a conventional color CRT.

2 is a perspective view of a shadow mask assembly used in the conventional color CRT of FIG.

3 is a perspective view of another shadow mask assembly of a slot structure.

4A is a top view of the shadow mask assembly of FIG. 4, and FIG. 4B is a cross-sectional view taken along the line IV-IV in FIG. 4A.

FIG. 5A is a perspective view of a shadow mask assembly according to the first embodiment of the present invention, and FIG. 5B is a cross-sectional view taken along the line V-V in FIG. 5A.

6A and 6B are partial perspective views of other damper members modified from the first embodiment.

FIG. 7A is a perspective view of a shadow mask assembly according to a second embodiment of the present invention, and FIG. 7B is a cross-sectional view taken along VII-VII in FIG. 5A.

8 is a cross-sectional view taken along the line VIII-VIII in FIG. 7A.

9A and 9B are partial perspective views of other damper members modified from the second embodiment.

10A-10D are top views of exemplary shadow mask assemblies according to a third embodiment of the present invention.

<Explanation of symbols for main parts of drawing>

10: shadow mask assembly

28a, 28b: frame bar

28c, 28d: elastic frame legs

52: shadow mask

53: Aperture

54: grill

55: bridge

56: damper wire

Before describing embodiments of the present invention, the principles of the present invention will be described below. FIELD OF THE INVENTION The present invention relates to the construction of shadow mask assemblies for use in color CRTs, wherein the slotted shadow mask is fixed on the pair of opposing frame bars with external tension therefrom. The shadow mask comprises a plurality of slot or dot apertures arranged in a plurality of columns in the y direction, a plurality of grill sections (grills) each extending in the y direction between each two columns of the aperture columns, and adjacent apertures. It is provided with a plurality of bridge sections (bridges) which pass between them and connect the grills respectively.

The shadow mask assembly includes a pair of damper wires or damper members disposed near both ends of the shadow mask, and each of the damper wires or damper members is disposed on the outermost grille to suppress or mitigate vibration of the shadow mask. .

In the conventional structure shown in Figs. 4A and 4B, the external tension applied to the shadow mask 27a in the y direction tends to push the aperture area of the shadow mask 27a to the rear of the shadow mask 27a, which is x It is more pronounced in the case of the shadow mask 27a having a specific cylinder which is curved in the direction and straight in the y direction. If the shadow mask 27a has a flat surface, the depression is less and can be substantially ignored.

On the other hand, the present inventors found that the outermost grilles 37a of the shadow mask bend forward of the aperture region to a position between 0 and tens of micrometers with respect to the front of the frame bars due to the tension applied to the shadow mask in the x direction. It was found to be prone. This is common to planar and cylindrical shadow masks and is believed to be attributable to or promoted in part by the fact that the outermost edges of the shadow mask 27a are free in the aperture region. The present invention solves this problem by stretching and stretching the damper wire on each of the outermost grills. Stretching the damper wire on the fin grill ensures secure contact with the front face of the shadow mask of the damper wire, thereby suppressing or mitigating the vibration of the shadow mask.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings. Like elements are denoted by like reference numerals.

5A and 5B, the shadow mask assembly used for the color CRT according to the first embodiment of the present invention is a pair of damper wires 56 on the outermost grille 54a of the shadow mask 52 of this embodiment. Has a structure similar to that shown in FIGS. 4A and 4B except that is stretched and stretched.

More specifically, the shadow mask assembly, indicated generically by reference numeral 10, includes a slotted shadow mask 52 and a pair of frame bars 28a and 28b and extends in the x direction (or scanning direction of the electron beam). The frame 28 and a pair of elastic frame legs 28c and 28d having a U-shape to secure the frame bars 28a and 28b together while applying elastic force to the frame bars 28a and 28b. Frame bars 28a and 28b support the shadow mask 52 in front of it.

The shadow mask 52 is slot-shaped, each of which has a plurality of slot apertures 53 and two columns of apertures 53 arranged in a plurality of columns in an aperture region of the shadow mask 52 for passing an electron beam. A plurality of grills 54 each extending in the y-direction in between, and a plurality of bridges 55 for connecting the two grilles 54 each passing between the two apertures 53 in the x-direction. Include. The shadow mask 52 is subjected to tension or stretching force in the y direction, that is, in the direction of extension of the elongated slot aperture 53. The ends of the damper wire 56 are fixed on the upper and lower surfaces of the frame bars 28a and 28b by fittings 57 with spring functions. Damper wire 56 is preferably made of metal or an alloy such as tungsten or stainless steel.

As shown in FIG. 5B, a pair of damper wires 56 extending onto the front surface of the outermost grille of the shadow mask 52 pushes the bent edge of the shadow mask to the rear with a strong pressing force. The edge of the shadow mask 52 is curved in the front direction of the CRT in the aperture region of the shadow mask 52 before the pressing force is applied by the damper wire 56 as shown by the dotted line in FIG. 5B. Thus, the surface of the edge of the shadow mask 52 in the aperture area is substantially at the same level as the front face of the framebars 28a and 28b. In order to further enhance the suppression function against the vibration of the shadow mask 52, it is preferable that the damper wire 56 be extended to the vicinity of the outermost edge of the outermost grill 54a of the shadow mask 52. The damper wire 56 is preferably made of a metal or alloy, such as tungsten or steel.

Referring to FIG. 6A, a variation from the shadow mask assembly 10 of FIGS. 5A and 5B includes a pair of stripe damper members 58 instead of damper wires 56. The stripe member 58 is in the form of a groove, and is fixed to the frame bars 28a and 28b, and the lower surface thereof extends the extension portion 58c of the stripe member 58 to the upper and lower portions of the frame bars 28a and 28b. Welding to the face makes contact with the edge of the shadow mask 52.

Referring to FIG. 6B, another variation from the shadow mask assembly 10 of FIGS. 5A and 5B includes a stripe damper member 58 having an L-shaped edge or flange. The grooved or L-shaped edge of the stripe member 58, which acts as a reinforcement, further improves the damping function of the stripe member 58 by providing sufficient strength to the stripe member 58 in preparation for distortion of the stripe member. The elongated portion 58d of the stripe member 58 shown in FIG. 6B has a spring function due to the rounded corner portion connecting the elongated portion and the welded portion of the striped member 58. The spring function of the elongate portion 58d provides an increase in the tensile force of the stripe member 58.

7A and 7B, the shadow mask assembly for a CRT according to the second embodiment of the present invention is characterized in that the damper wire (first damper wire) (second damper wire) 11 is used in the first embodiment. Similar to the first embodiment except that it is disposed on the rear surface of the shadow mask 52 adjacent to the first damper wire 56. The first and second damper wires 56, 11 are fixed on the frame bars 28a, 28b by means of a spring-loaded component 57.

For the construction of the second embodiment, the first and second damper wires 56, 11 extending near respective edges of the shadow mask are in the outermost grill 54a to damp vibration of the shadow mask 52. Sandwich the shadow mask 52. There may be three or more damper wires at each edge of the shadow mask 52.

The example configuration in which the first damper wire 56 is disposed outside of the second damper wire 11 provides an excellent damping function to the damper wires 56 and 11 that damp the vibrations of the shadow mask. However, another configuration in which the second damper wire 11 is disposed outside the first damper wire 56 also provides a damping function to the damper wire that damps the vibration of the shadow mask 52. In addition, the first and second damper wires 56 and 11 may be disposed to face each other with the shadow mask 52 interposed therebetween, as shown by a dotted line in FIG. 7B.

Referring to FIG. 8, a desired variant from the second embodiment is that the front faces of the frame bars 28b and 28a include a trench 59 in which the second damper wire 11 is received. . While fabricating a variant of the shadow mask, the second damper wire 11 is received in a trench 59 formed on the frame bars 28a, 28b and welded using a component such as a flat spring or a coil spring. This is fixed to the frame bar. Subsequently, the shadow mask is fixed on the frame bar by applying external force in the y-direction to the frame bars 28a and 28b as in the prior art.

Subsequently, the first damper wire 56 is fixed to the frame bars 28a and 28b by welding so as to extend in front of the shadow mask 52. The cross section of the groove 59 may be V-shaped, U-shaped, rectangular and square depending on the size and shape of the cross section of the second damper wire 11. The depth and shape of the trench 59 should be defined so that the top of the second damper wire 11 does not protrude from the front of the frame bars 28a, 28b to which the shadow mask 52 is welded. The trench 59 is used to locate the correct position of the second damper wire 11.

Referring to FIG. 9A, the modification from the second embodiment is that the first and second damper wires 56 of the second embodiment are replaced with the first and second stripe dampers 13, 12, respectively, and each cross section. It has this rectangle. The second stripe damper 12 is housed in a flat rectangular trench 59 formed on the frame bars 28a, 28b. The positional configurations of the first and second stripe dampers 13 and 12 and the shadow mask 52 are the same as in the second embodiment or modifications thereof.

The second stripe damper 12 may have a flange or edge extension at one edge that projects rearward to improve mechanical strength. The first stripe damper 13 may be grooved as shown in FIG. 6A, and may also have a flange or edge extension projecting to the rear side as shown in FIG. 6B. The flange may be arranged to engage the edge of the shadow mask 52. Striped dampers 12 and 13 with flat surfaces in contact with shadow mask 52 have good damping capabilities due to the large contact surface. FIG. 9B includes a second damper 12 in the form of a stripe disposed on the rear side of the shadow mask 52 and a first damper 13 consisting of wires disposed on the front side of the shadow mask 52 along the outermost grille. .

10A to 10D, an example of the shadow mask assembly in the CRT according to the third embodiment includes an outermost grille having a specific configuration. The outermost grille 54a of the shadow mask 16 in the third embodiment has at least one cutout 17 on its edge. The cutout 17 deforms the vibration pattern of the shadow mask 16 by changing the distribution of tensile strength in the shadow mask 16. The combination of damper 56 and cutout 17 improves the damping function of vibration of shadow mask 16. The cutout 17 may be formed along the entire edge of the outermost grill 54a and may also be formed at a portion thereof, for example at the center of the edge of the outermost grill 54a.

FIG. 10A shows a curved cutout 17 formed along the entire edge of the outermost grill 54a, FIG. 10B shows a cutout with a trapezoidal shape formed along the entire edge, and FIG. A semicircular cutout (or semi-elliptical cutout) 17 formed at the center of the edge is shown, and FIG. 10D shows a rectangular cutout formed at the center of the edge. The cutouts 17 may be formed in two or more numbers as long as the edge can accommodate multiple cutouts. The damper may be a wire or stripe member as disclosed herein.

The pair of dampers may be disposed on the front side or the back side of the shadow mask 16. Damper 56 may be disposed outside or inside the cutout, as long as a portion thereof pushes the outermost grille.

The above embodiments have been described for illustrative purposes only, and the present invention is not limited to the above embodiments, and various modifications or variations can be readily made by those skilled in the art without departing from the scope of the present invention.

According to the shadow mask assembly of the present invention, a damper member on the outermost grille pushes an end of the shadow mask, which can be bent toward the front of the shadow mask, thereby effectively bringing the damper member into close contact with the shadow mask. . This improves the damping function of the damper member and improves the image quality of the CRT having the shadow mask.

Claims (11)

In the shadow mask assembly used for color CRT, A plurality of apertures 53 arranged in a plurality of columns, a grill 54 extending between each two columns of the apertures 53, and a plurality each connecting two of the grills 54. A shadow mask 52 having a bridge 55 of; A pair of frame bars (28a, 28b) for supporting the edge portions of the shadow mask (52) at the back of the shadow mask (52) such that the shadow mask (52) is subjected to external tension; And In order to push the shadow mask 52 toward its back, a pair of each of which extends on the front face of the shadow mask 52 and on the outermost grille 54a of the grilles 54. Shadow mask assembly, characterized in that it comprises a first damper member (56). 2. The apparatus of claim 1, further comprising a pair of second damper members 11 extending on the rear surface of the shadow mask 52 and on the outermost grille 54a of the grilles 54. Shadow Mask Assembly. 2. The shadow mask assembly of claim 1, wherein each of the frame bars (28a, 28b) has a trench (59) for receiving the second damper member (11) therein. 4. The shadow mask assembly of claim 3, wherein said trench (59) has a depth corresponding to a thickness of said second damper member (12). 3. Shadow mask assembly according to claim 2, characterized in that the pair of first damper members (56) are disposed on the shadow mask (52) outside of the pair of second damper members (11). 2. Shadow mask assembly according to claim 1, characterized in that the outermost grille (54a) of the grilles (54) has a cutout (17) at its outer periphery. 2. The shadow mask assembly of claim 1, wherein at least one of said first damper members (56) is a wire. 2. The shadow mask assembly of claim 1, wherein at least one of said first damper members (58, 13) is a stripe member. 9. The shadow mask assembly of claim 8, wherein the stripe member (58) has an edge extension (58b). 10. The shadow mask assembly of claim 8, wherein the stripe member is in the shape of a trough. A color CRT comprising a shadow mask assembly as defined in claim 1.