KR20040107532A - Cathode ray tube - Google Patents

Abstract

PURPOSE: A cathode ray tube is provided to minimize the volume of movement of electron beam due to the influence of magnetic field by optimizing the shape of an inner shield, thereby improving color purity. CONSTITUTION: A cathode ray tube includes a panel(10), a funnel(20), a shadow mask(80), a mask frame(90), and an inner shield(100). The funnel is attached to the back side of the panel. The shadow mask is arranged having a predetermined distance from the inner side of the panel and has a plurality of electron beam passage holes. The mask frame fixes and supports the shadow mask. The inner shield shields external terrestrial magnetism. The length of the diagonal axis of the inner shield is longer than at least one of the shorter axis, longer axis and diagonal axis of the mask frame.

Description

Cathode Ray Tube {CATHODE RAY TUBE}

The present invention relates to a cathode ray tube, and more particularly, to a cathode ray tube capable of improving color purity of a screen by optimizing the shape of an inner shield to minimize the amount of movement of an electron beam under the influence of a magnetic field.

In general, a cathode ray tube converts an electrical signal into an electron beam, and emits the electron beam onto a phosphor screen to implement an optical image. The cathode ray tube is a display device widely used because of its excellent display price ratio.

Such a cathode ray tube will be described with reference to the accompanying drawings.

1 is a schematic view showing a cathode ray tube according to the prior art.

As shown in FIG. 1, the cathode ray tube includes a panel 201 which is a front glass, a funnel 202 which is a rear glass which is combined with the panel 201 to form a vacuum space, and an inner surface of the panel 201. A phosphor screen 213 applied to the light emitting element, an electron gun 206 through which the electron beam 205 emitting the phosphor screen 213 is emitted, and a predetermined distance from an outer circumferential surface of the funnel 202. A deflection yoke 207 for deflecting the electron beam 205 toward the phosphor screen 213, a shadow mask 208 provided at a predetermined distance from the phosphor screen 213, and the shadow mask 208. An inner shield that is fixed / supported to the mask frame 209 and is formed to extend from the panel 201 side to the funnel 202 side to shield external geomagnetic fields and prevent color purity from deteriorating due to magnetic field influences. 210) back light It is configured to.

2 and 3, the shadow mask 208 has an effective surface portion 208b in which a plurality of electron beam through holes 208a are formed, and a substantially tube axis Z around the effective surface portion 208b. A skirt portion 208c extending in the -axis) direction and fixed to the side wall portion 209a of the mask frame 209.

The mask frame 209 is formed upright in the tube axis (Z-axis) direction of the cathode ray tube, and the side wall portion 209a to which the skirt portion 208c of the shadow mask 208 is fixed forms a long side and a short side. do.

The inner shield 210, as shown in Figure 4, the shield body 210a of the thin plate to form the opening 210c on both sides, and bent to the end of the shield body 210c is formed by the mask frame ( It consists of a flange part 210b fixed to 209.

The phosphor screen 213 is applied in a direction substantially parallel to the minor axis (Y-axis) of the panel 201 and has a predetermined width Bd, respectively, as shown in FIG. Is applied between the black layer 214 to which a good material is applied, and the blue 212B, green 212G, and red 212R that are sequentially applied with a predetermined width Gs between the black layer 214. It consists of three phosphors 212. Thus, when the electron beam 205 is landed on each phosphor 212, the electron beam 205 is separated by the black layer 214 to emit the appropriate phosphor 212.

On the other hand, when the movement of the electron beam 205 occurs due to external factors such as a geomagnetic field fluctuation outside the cathode ray tube, the electron beam 205 causes the black layer 214 to move due to the movement of the electron beam 205. Out of the width (Bd) of affects the adjacent phosphor. The color bleeding phenomenon occurs when the color spreads due to such an effect, and as described above, the margin in which the electron beam 205 does not cause interference with other adjacent phosphors is defined as the color purity margin. The color purity margin is related to the width Bd of the black layer 214, the width Gs of the phosphor 212, and the width Bg of the electron beam 205. same.

Color purity margin = ((2Bd + Gs) -Bg) / 2 (1)

Here, Bd is the width of the black layer, Gs is the width of each phosphor, and Bg is the width of the electron beam.

In the conventional cathode ray tube configured as described above, the electron beam 205 emitted from the electron gun 206 is deflected by the deflection yoke 207 and passes through the electron beam through hole 208a of the shadow mask 208. Landed on the phosphor screen 213 on the inner surface of the panel 201 to emit an image of each phosphor 212.

In the above process, the shadow mask transmittance when the electron beam 205 passes through the shadow mask 208, and the screen transmittance when passing through the phosphor screen 213 and finally, the panel 201 of the panel 201. The difference in luminance is caused by the glass transmittance, and all three transmittances are lowered from the center of the panel 201 toward the periphery of the panel 201. This causes a phenomenon in which the luminance of the entire screen of the panel 201 is not uniform. Moreover, in accordance with the current trend that the inner and outer surfaces of the curved panel having a small radius of curvature turn into a flat panel having a radius of curvature of which the outer surface is almost infinite, the outer surface of the panel 201 is flattened so that the center portion of the panel 201 is flat. The wedge rate, which is the ratio of the glass thickness of the periphery of the panel to the glass thickness of the panel, becomes large, so that the difference between the light transmittances of the central and periphery of the panel 201 becomes large so that the brightness of the screen is not uniform. The phenomenon becomes worse.

As a method for improving the non-uniformity of the brightness, a glass having a high light transmittance is applied to the panel 201 to increase the light transmittance at the periphery of the panel, but the glass having a high light transmittance has a sharpness according to the contrast of the screen. There was a problem that the in-contrast characteristic was lowered. In addition, as a method for improving the problem of lowering the contrast characteristics has been used a method of coating a colorant or a film containing a colorant on the outer surface of the panel glass, such a coating or film is attached to the cathode ray tube The increase in the number of parts and processes in the manufacturing process has the disadvantage that eventually increases the price of the cathode ray tube.

Therefore, as another method for simultaneously improving the luminance unevenness and contrast characteristics, tint or dark tint glass for coloring the panel glass itself is applied to the panel 201. However, even when such a tint or dark tint glass is applied to the panel, there is a problem that the transmittance sharply decreases toward the periphery of the panel.

That is, as shown in Table 1, when a coating is applied to a panel having a thickness Tc of 12.5 mm at the center of the panel and a thickness Tco of 27.5 mm at the periphery of the panel, the panel having a wedge rate of 220% Although the light transmittance at the center of the panel was 54.41% and the light transmittance at the periphery of the panel was 46.51%, the light transmittance at the center of the panel was 51.15% while the light transmittance at the center of the panel was 25.56%. . Accordingly, the luminance of the periphery of the panel is 15fl from 50fl to 35fl when the tinted glass is applied than when the coated glass is applied, and it is non-uniform compared to the center of the panel.

panel Center Glass Transmittance (%) Peripheral Glass Transmittance (%) Peripheral luminance (fl) coating 54.41 46.51 50 Tint 51.15 25.56 35

On the other hand, the wedge of the panel for the purpose of solving the problem that the transmittance is sharply reduced at the periphery of the panel to reduce the uniformity of brightness, and at the same time to reduce the breakage in the thermal process due to the weight reduction and glass thickness difference of the panel. A method of reducing the rate is being considered, that is, reducing the thickness of the panel's periphery by increasing the panel's wedge ratio to increase the light transmittance at the panel's periphery and to reduce the difference in luminance at the center and the periphery of the panel. However, as the wedge rate of the panel is reduced, the inner surface of the panel becomes flatter, in which case the curvature of the shadow mask having a dome shape while maintaining a constant distance from the inner surface of the panel becomes flat as the inner surface of the panel becomes flat. As it becomes flatter, its structural strength is lowered, resulting in deterioration of impact resistance and howling characteristics of the shadow mask.

Therefore, in order to improve the luminance non-uniformity, there is a limit to reducing the wedge ratio of the panel. Accordingly, the width Gs of the phosphor 212 of the phosphor screen 213 corresponding to the periphery of the panel 201. In order to increase the luminance of the periphery of the panel 201 to increase the luminance, the method of improving the nonuniformity of the luminance is considered.

That is, as shown in Table 2, when the width (Gs) of the phosphor 212 around the panel 201 is increased by about 24% from 185 μm to 230 μm when the tinted panel is applied than when the coated panel is applied, The luminance of the periphery of the panel 201 is increased by 15fl from 35fl to 50fl than before the width Gs of the phosphor 212 is increased, so that the luminance of the panel 201 is uniformly displayed on the entire surface.

panel Center phosphor width (㎛) Perimeter phosphor width (μm) Peripheral luminance (fl) Direction margin coating 170 185 50 25 Tint 160 230 50 18

However, if the width Gs of the phosphor 212 at the periphery of the tinted panel 201 is increased as described above, the width Gs of the phosphor 212 is increased while the black around the phosphor 212 is increased. Since the width Bd of the layer 214 is reduced, the width of the electron beam 205 obscured by the black layer 214 becomes smaller so that the electron beam 205 is moved by a change in the direction of the small magnetic field. Even in this case, the electron beam 205 does not land on an appropriate phosphor and affects the surrounding phosphors. Therefore, the color purity characteristic of the peripheral portion of the panel 201 is deteriorated. That is, the direction margin indicating the degree of deterioration of color purity characteristics due to the influence of the geomagnetic field is reduced by about 28% from 25 degrees to 18 degrees in the case of the coated panel than in the case of the tinted panel.

And, as shown in FIG. 6, the magnetic field applied to the electron beam by the inner shield 210 when the electron beam 205 is deflected toward the shadow mask 208 by the deflection yoke 207 when the geomagnetic field changes and changes direction. Although the influence of is reduced, the electron beam passing through the electron beam through hole 208a of the shadow mask 208 is the distance Dc between the center of the panel 201 and the center of the shadow mask 208 and the panel 201. Through the gap Dp between the inner surface of the mask frame 209 and the side wall portion 209a of the mask frame 209, the magnetic field is completely exposed to the magnetic field, and thus, the amount of movement of the electron beam increases due to a sensitive reaction with the magnetic field.

The present invention is to solve the above problems of the prior art, an object of the present invention is to increase the phosphor width of the phosphor screen in the periphery of the panel in the panel to which the tint or dark tint glass is applied, for uniformity of brightness In this case, the inner shield of the optimal shape that can effectively shield the geomagnetic field can be prevented to prevent the electron beam from moving and the color purity of the screen is lowered even if the geomagnetic field decreases in the direction margin of the geomagnetic field. It is to provide a cathode ray tube containing.

1 is a schematic view showing a cathode ray tube according to the prior art.

2 is a plan view illustrating a state in which a shadow mask and a mask frame are assembled in a cathode ray tube according to the related art.

3 is a cross-sectional view of FIG. 2.

Figure 4 is a perspective view showing the inner shield of the cathode ray tube according to the prior art.

5 is an enlarged plan view of a portion of a phosphor screen of a cathode ray tube according to the related art.

6 is a cross-sectional view showing the main portion of the cathode ray tube according to the prior art.

7 is a schematic view showing a cathode ray tube according to the present invention.

8 is a cross-sectional view showing a panel of a cathode ray tube according to the present invention.

9 is a plan view showing a panel of a cathode ray tube according to the present invention.

10 is a graph showing a change in the panel thickness from the center portion to the peripheral portion of the panel in the cathode ray tube according to the present invention.

11 shows the curvature of the long axis (X-axis), short axis (Y-axis), diagonal axis (D-axis) of the panel of the cathode ray tube according to the present invention, and the long axis (X-axis), short axis (Y- Axis), the curvature of the diagonal axis (D-axis) is a graph shown.

12 is a plan view illustrating a state in which a shadow mask and a mask frame are assembled in a cathode ray tube according to the present invention.

FIG. 13 is a cross-sectional view of FIG. 12.

14 is a perspective view showing a mask frame of a cathode ray tube according to the present invention.

15 is a graph showing the relationship between the curvature of the shadow mask of the cathode ray tube and the height of each part of the mask frame according to the present invention.

16 is a cross-sectional view showing the main portion of the cathode ray tube according to the present invention.

17 is a perspective view showing the inner shield of the cathode ray tube according to the present invention.

18 is a graph showing the height of the diagonal shaft portion of the inner shield in which the interference phenomenon of the electron beam is generated in the cathode ray tube according to the present invention.

19 is a graph showing a change in beam movement amount according to the change of direction of the geomagnetic field in the cathode ray tube according to the present invention.

20 is a graph showing a change in beam movement amount when changing the geomagnetic field direction with respect to a change in the height of the inner shield in the cathode ray tube according to the present invention.

*** Explanation of symbols for the main parts of the drawing ***

10: panel 20: funnel

80: shadow mask 80h: long axis of the shadow mask

80v: Short axis of shadow mask 80d: Diagonal axis of shadow mask

90: mask frame 90h: major axis of mask frame

90v: short axis of mask frame 90d: diagonal axis of mask frame

100: inner shield 100d: diagonal axis of the inner shield

H: Diagonal shaft height of the inner shield

Cathode ray tube according to the present invention for achieving the above object is a panel having a substantially flat outer surface, a funnel mounted on the rear side of the panel, and disposed at regular intervals from the inner surface of the panel and a plurality of electron beam passing holes The inner shield comprising a shadow mask to be formed, a mask frame for fixing / supporting the shadow mask, and an inner shield installed in a form extending from the funnel side to the panel side to shield an external geomagnetic field. The height of the diagonal axis of the mask frame is characterized in that it is formed higher than at least one of the maximum height of the short axis, the long axis portion and the diagonal axis portion.

Hereinafter, with reference to the accompanying drawings will be described a preferred embodiment of the cathode ray tube according to the present invention.

As shown in FIG. 7, the cathode ray tube according to the present invention includes a panel 10 which is a front glass, a funnel 20 which is a rear glass which is combined with the panel 10 to form a vacuum space, and the panel 10. Phosphor screen 130 that is applied to the inner surface of the panel acts as a light emitter, an electron gun 60 that emits the electron beam 50 for emitting the phosphor screen 130, and a predetermined from the outer peripheral surface of the funnel 20 A deflection yoke 70 provided at intervals to deflect the electron beam 50 toward the phosphor screen 130, a shadow mask 80 provided at a predetermined distance from the phosphor screen 130, and the shadow mask The mask frame 90 for fixing / supporting the 80 and the panel 10 extends from the panel 10 side toward the funnel 20 to shield external geomagnetic fields, thereby preventing color purity from deteriorating due to magnetic field effects. Inner shield 100 to say, A spring supporter 140 installed inside the panel 10 to fix the support spring 110 to elastically support the mask frame 90 to the panel 10, and an outside of the panel 10. Is installed around the surface is configured to include a reinforcing band 120 and the like to distribute the stress generated in the panel 10 and the funnel 20.

As illustrated in FIGS. 8 and 9, the panel 10 has an outer surface substantially formed in a plane, and an inner surface thereof is formed with a curved surface having a predetermined curvature. In addition, the panel 10 includes an effective surface portion 11 on which the phosphor screen 130 is applied, and a skirt portion 12 extending in the tube axis direction (Z-axis) around the effective surface portion 11. Is made of.

The thickness of the panel 10 is, as shown in FIG. 10, in consideration of the explosion-proof characteristics, the thickness Tv of the short axis portion 10v of the panel than the thickness Tc of the central portion 10c of the panel 10, It is thickly formed in order of the thickness Th of the major axis part 10h, and the thickness Td of the diagonal axis part 10d. Therefore, as shown in FIG. 11, the radius of curvature Rv 'of the minor axis (Y-axis) of the inner surface of the panel 10 is greater than the radius of curvature Rh' of the major axis (X-axis), and the major axis X The radius of curvature Rh 'of the -axis) is larger than the radius of curvature Rd' of the diagonal axis D-axis.

12 and 13, the shadow mask 80 has an effective surface portion 82 in which a plurality of electron beam through holes 81 are formed, and a tube axis Z around the effective surface portion 82. And a skirt portion 83 extending in the -axis) direction and fixed to the side wall portion 91 of the mask frame 90.

Although the curvatures of the long axis (X-axis) and short axis (Y-axis) and the diagonal axis (D-axis) of the shadow mask 80 are formed with curvatures corresponding to the curvature of the inner surface of the panel 10, the shadow In order to increase the strength of the mask 80, it is preferable to reduce the radius of curvature of the shadow mask 80 rather than the radius of curvature of the inner surface of the panel 10, and in particular, the diagonal axis (D-axis) of the shadow mask 80. It is preferable to make the radius of curvature of C) smaller than the radius of curvature of the diagonal axis (D-axis) of the inner surface of the panel 10. That is, as shown in FIG. 11, the radius of curvature Rv of the short axis (Y-axis) of the shadow mask 80 is greater than the radius of curvature Rh of the long axis (X-axis), and the long axis (X-axis). Radius of curvature Rh is larger than the radius of curvature Rd of the diagonal axis D-axis. Further, the radius of curvature Rv of the minor axis (Y-axis) of the shadow mask 80 is smaller than the radius of curvature Rv 'of the minor axis (Y-axis) of the inner surface of the panel 10, and the shadow mask 80 The radius of curvature Rh of the major axis (X-axis) of the panel 10 is smaller than the radius of curvature Rh 'of the major axis (X-axis) of the inner surface of the panel 10, and the diagonal axis D- of the shadow mask 80 is Axis of curvature Rd is smaller than the radius of curvature Rd 'of the diagonal axis D-axis of the inner surface of the panel 10. Therefore, when the centers of the shadow mask 80 and the inner surface of the panel 10 coincide on the same axis, between the long axis portion, the short axis portion, the diagonal axis portion of the shadow mask 80 and the inner surface of the panel 10. In the tube axis direction, there are constant distances Dh, Dv, and Dd, where the distance Dd between the diagonal axis portion 80d of the shadow mask 80 and the inner surface of the panel 10 is The largest, the distance Dh between the long axis portion 80h of the shadow mask 80 and the inner surface of the panel 10, the short axis 80v of the shadow mask 80 and the inner surface of the panel 10. Smaller in the order of the interval Dv.

As shown in FIGS. 14 and 15, the mask frame 90 is formed upright in the tube axis (Z-axis) direction of the cathode ray tube, and the skirt portion 83 of the shadow mask 80 is fixed to the mask frame 90. The side wall portion 91 is formed while forming a long side and a short side having predetermined lengths L and S, and are supported by the spring supporter 11 and the support spring 14 coupled to the mask frame 90. It is elastically supported inside the panel 10. The height h of the long axis portion 90h of the mask frame 90, the height v of the short axis portion 90v, and the height d of the diagonal axis portion 90d are the curvatures of the shadow mask 80. (I.e., the radius of curvature Rv, Rh, Rd), the height v of the short axis 90v of the mask frame 90 is the largest, and the height of the major axis 90h is (h) and small in order of the height d of the diagonal shaft part 90d. However, the present invention is not limited thereto, and the height h of the long axis portion 90h of the mask frame 90 may be greater than the height v of the short axis portion 90v.

On the other hand, as described above, since the electron beam 50 passing through the electron beam through hole 81 of the shadow mask 80 is completely exposed to the geomagnetic field, the amount of movement of the electron beam 50 is large, in particular, the panel In order to increase the width of the phosphor in the periphery of the panel 10 in order to improve the nonuniformity of luminance caused by tinting, the direction margin indicating the degree of deterioration of color purity due to the amount of electron beam movement due to the change in the direction of the geomagnetic field is reduced. Therefore, the color purity of the screen is likely to be poor.

Therefore, in order to reduce the amount of movement of the electron beam due to such a change in the geomagnetic field, the distance between the shadow mask 80 and the inner surface of the panel 10 is reduced or the material of the inner shield 100 is changed to change the electron beam 50. Can reduce the amount of movement. However, when the gap between the shadow mask 80 and the inner surface of the panel 10 is reduced, the phosphor is not applied well in the process of applying the phosphor screen 130, so that a defect of the phosphor screen and a defect due to the handling of an operator may occur. When the material of the inner shield 100 is changed, a component cost of the inner shield 100 is increased.

Accordingly, in order to reduce the amount of movement of the electron beam due to the influence of the geomagnetic field, as shown in FIG. 16, the height H of the inner shield 100 that shields the geomagnetic field is increased to increase the height of the shadow mask 80. By shielding the geomagnetic field acting on the electron beam 50 passing through the electron beam passing hole 81, the amount of movement of the electron beam 50 can be reduced.

Here, the distance between the diagonal axis portion 80d of the shadow mask 80 and the diagonal axis portion 10d of the panel 10 is equal to the long axis portion 80h of the shadow mask 80 and the panel 10. It is formed larger than the interval between the major axis portion 10h and the interval between the minor axis portion 80v of the shadow mask 80 and the minor axis portion 10v of the panel 10, and passes through the electron beam of the shadow mask 80. Since the electron beam 50 passing through the ball 81 reaches the phosphor screen 130 on the inner surface of the panel 10 at a predetermined distance from the diagonal axis portion 80d of the shadow mask 80, the inner It is possible to increase the height of the diagonal shaft portion 100d of the shield 100.

The inner shield 100 according to this, as shown in Figure 17, the shield body 101 of the thin plate forming openings on both sides, and bent to the end of the shield body 101 is formed in the mask frame 90 The inner shield 100 is formed to extend to have a predetermined height (H) in the direction toward the inner surface of the panel 10 in the flange portion 102 and the diagonal shaft portion (100d) of the front surface of the inner shield 100 fixed to the The extension portion 103 is formed to extend along a long axis (X-axis) and along a short axis (Y-axis) to have a predetermined width W1 and Ws, respectively.

Here, in order to optimize the shielding effect of the geomagnetic field on the inner beam 100 passing through the electron beam through hole 81, the extension portion 103 of the inner shield 100 has a long axis. The width Wl extending along the (X-axis) is preferably formed to be 50% or more of the intermediate length L / 2 of the long side length L of the mask frame 90, and the inner shield ( The width Ws of the extension portion 103 of the 100 extending along the short axis (Y-axis) is 50% or more of the intermediate length S / 2 of the short side length S of the mask frame 100. It is preferably formed.

This can be summarized as follows.

Wl / (L / 2) ≥ 0.5 (2)

Ws / (S / 2) ≥ 0.5 (3)

Meanwhile, the thickness of the center portion 10c of the panel 10 in the tinted panel in which the wedge rate of the panel 10 is 240% or less, the glass transmittance of the center portion of the panel is 54% or less, and the glass transmittance of the peripheral portion of the panel is 26% or less. The thickness Td of the diagonal shaft portion 10d of the 12.5 mm panel 10 is 24.25 mm, and the tube axial distance Dc from the center of the panel 10 to the center of the shadow mask 80 is 22.2. mm and the height d of the diagonal axis portion 90d of the mask frame 90 is 54.8 mm, the axis from the diagonal axis portion 10d of the panel 10 to the diagonal axis portion 90d of the mask frame 90 is shown. Since the direction distance is 25.95 mm, it is possible to increase the height H of the diagonal shaft portion 100 d of the inner shield 100 to 80.75 mm. However, as shown in FIG. 18, when considering the deflection angle of the electron beam, when the height H of the extension 103 of the inner shield 100 exceeds 71.8 mm, the inner shield 100 In order to prevent the phenomenon that the electron beam 50 is interfered by the end of the extension portion 103 of the inner shield 100 because the interference with the electron beam 50 at the end of the extension 103. The height H of the extension part 103 may be formed to a maximum height of 71.8 mm or less. In this case, the height H of the diagonal axis part 100d of the inner shield 100 may be defined by the mask frame 90. The height d of the diagonal shaft portion 90d can be raised from 54.8 mm to 17 mm. In addition, since the height H of the extension 103 of the inner shield 100 should be higher than the height d of the diagonal axis 90d of the mask frame 90, the extension of the inner shield 100 ( It is preferable to form height H of 103) 54.8 mm or more. At this time, the difference between the diagonal shaft portion 10d of the panel 10 and the end of the extension 103 of the inner shield 100 (that is, the diagonal shaft portion 100d) is 8.95 mm.

This can be summarized as follows.

0 <His / Dp <0.66 (4)

Here, His is the height of the diagonal axis portion 100d of the inner shield 100 based on the end of the diagonal axis portion 90d of the mask frame 90, that is, the diagonal axis portion 100d of the inner shield 100. The height H of the mask frame 90 is obtained by subtracting the height d of the diagonal axis portion 90d of the mask frame 90, and Dp is the diagonal axis portion 10d of the panel 10 and the mask frame 90. It is the interval between the diagonal shaft portions 90d.

Referring to the operation of the cathode ray tube according to the present invention as described above are as follows.

That is, as shown in Table 3 and FIGS. 19 and 20, the amount of movement of the electron beam gradually increases as the direction of the magnetic field changes, but the height H of the diagonal shaft portion 100d of the inner shield 100 is increased. If the distance between the inner surface of the panel 10 and the diagonal shaft portion 100d of the inner shield 100 is reduced, the amount of magnetic field affecting the electron beam is reduced, so that the amount of movement of the electron beam according to the change in the direction of the geomagnetic field is reduced. It can be seen that it can be reduced.

Inner Shield Diagonal Shaft Height (mm) Movement amount of electron beam according to the change of geomagnetic field direction (㎛) 5 degrees 10 degree 15 degrees 20 degrees 25 degrees 55 16 21 26 31 36 58 15 19.5 24 28.5 35 61 14.8 18 23.5 27 34.5 64 14 17.5 22 26.2 34 67 13.7 16.8 21.7 25.2 33.2 70 13 16 21.2 25 30 73 12 15 20 23.5 27

According to the present invention, the electron beam passing through the electron beam through hole generated due to the large gap between the panel and the mask frame does not change the electron beam generated by the influence of the magnetic field before reaching the phosphor screen on the inner surface of the panel without changing the material of the inner shield. By increasing the height of the diagonal axis portion of the inner shield, the amount of movement of the electron beam can be reduced.

panel Center / peripheral light transmittance (%) Mask Frame Diagonal Shaft Height (d, mm) Inner Shield Diagonal Shaft Height (H, mm) Center / peripheral phosphor width (Gs, μm) Electron Beam Shift (㎛) Direction margin coating 54.41 / 46.51 54.8 0 170/185 35 25 Tint 51.15 / 25.56 54.8 0 160/230 35 18 Tint 51.15 / 25.56 54.8 71.8 160/230 29 25

That is, as shown in Table 4, by increasing the inner shield height to a maximum of 71.8 mm, the amount of movement of the electron beam is reduced by 6 µm or more, and the direction indicating that a change in the movement of the electron beam occurs due to a change in the direction of the geomagnetic field. You can improve the margin by seven degrees.

As described above, the cathode ray tube according to the present invention has the effect of improving the color purity of the screen by optimizing the shape of the inner shield to minimize the amount of movement of the electron beam under the influence of the magnetic field. In addition, even if the width of the phosphor at the periphery of the panel is increased in order to improve the luminance non-uniformity caused by panel tinting, the amount of movement of the electron beam due to the magnetic field change can be reduced, thereby preventing the color purity from being lowered.

Claims (10)

A panel having a substantially flat outer surface, a funnel mounted to the rear side of the panel, a shadow mask disposed at regular intervals from the inner surface of the panel and having a plurality of electron beam through holes formed thereon, and fixing / supporting the shadow mask. In a cathode ray tube composed of a mask frame and an inner shield that shields an external geomagnetic field, The inner shield is installed in a form extending from the funnel side to the panel side, wherein the height of the diagonal axis of the inner shield is formed higher than at least one of the maximum height of the short axis, the long axis and the diagonal axis of the mask frame. Cathode ray tube characterized in that. The method of claim 1, wherein the height of the diagonal axis portion of the inner shield is H, the height of the short axis portion of the mask frame is v, and the height of the long axis portion of the mask frame is h. Cathode ray tube, characterized in that. H> h> v 2. The method of claim 1, wherein the height of the diagonal axis portion of the mask frame is d, the height of the short axis portion of the mask frame is v, and the height of the major axis portion of the mask frame is h. Cathode ray tube, characterized in that. h> v> d The cathode ray tube according to claim 1, wherein the width of the diagonal axis portion of the inner shield extending along the long side is Wl, and the length of the long side of the mask frame is L. Wl / (L / 2) ≥ 0.5 The cathode ray tube according to claim 1, wherein the width of the diagonal axis portion of the inner shield extending along the short side is Ws, and the length of the short side of the mask frame is S. Ws / (S / 2) ≥ 0.5 The cathode ray tube according to claim 1, wherein the glass tube has a condition that the following condition is satisfied when the glass transmittance of the central portion of the panel is Pc. Pc ≤ 54% The cathode ray tube according to claim 1, wherein the glass transmittance at the periphery of the panel is Pco, and the following conditions are satisfied. Pco ≤ 26% The cathode ray tube according to claim 1, wherein the following condition is satisfied when a thickness of the center portion of the panel is Tc. Tc ≤ 13.5 mm The cathode ray tube according to claim 1, wherein the thickness of the center portion of the panel is referred to as Tc, and the thickness of the peripheral portion of the panel is referred to as Tco. Tco / Tc ≤ 2.4 The height of the diagonal axis portion of the inner shield with respect to the end of the diagonal axis portion of the mask frame is called His, and the distance between the diagonal axis portion of the panel and the diagonal axis portion of the mask frame is Dp. When the cathode tube is satisfied. 0 <His / Dp <0.66