KR20030072432A - Cathode ray tube having shield member which reduces effect of external magnetism - Google Patents

Abstract

PURPOSE: A cathode ray tube is provided to achieve improved color purity by preventing the electron beam scanned to the phosphor screen from being mis-landed by the influences caused due to a terrestrial magnetism applied from an external source. CONSTITUTION: A cathode ray tube comprises a panel(20) having a screen portion and a side surface formed along the circumference of the screen portion; a funnel(24) connected to the panel, and which has an outer surface on which a deflection unit(28) is mounted; a neck(26) connected to the funnel, and which has an interior in which an electron gun(30) for generating electron beams is mounted; a color discrimination unit(32) mounted in the panel, and which discriminates colors of the electron beams and permits the electron beams to reach the corresponding phosphors; and a shield member(40) connected to the color discrimination unit, and which is disposed toward the neck and shields a terrestrial magnetism which gives influences to the electron beam scanning orbit. The shield member includes a pair of longer sides(40a) and a pair of shorter sides. Each of the longer sides has one or more slots elongated in the widthwise direction of the screen portion of the panel. A flap is disposed at the panel side of the slot in such a manner that the flap is extended toward the inside of the shield member.

Description

Cathode ray tube with shield member to reduce the influence of external magnetic field {CATHODE RAY TUBE HAVING SHIELD MEMBER WHICH REDUCES EFFECT OF EXTERNAL MAGNETISM}

The present invention relates to a cathode ray tube, and more particularly, to a cathode ray tube provided with a shield member so that an electron beam scanned from an electron gun to a fluorescent screen can be suppressed from being mislanded under the influence of geomagnetism.

Cathode ray tubes, which are widely used in color televisions, computer monitors, and the like, in an image display device, realize a predetermined image by scanning an electron beam generated from an electron gun onto a fluorescent screen coated with R, G, and B phosphors.

At this time, since the electron beam must be scanned not only at the center portion of the fluorescent screen having a substantially rectangular shape but also at its periphery to emit phosphors applied to the portion, the electron beam is deflected by the magnetic field formed from the deflecting device. The desired phosphor position is reached.

However, in the scanning process of the electron beam, when the electron beam is affected by a magnetic field acting outside the cathode ray tube, for example, geomagnetic, etc., the so-called miss landing phenomenon that does not reach the phosphor to be finally reached but reaches another phosphor. To deteriorate the color purity characteristics of the cathode ray tube.

Looking at the mis-landing phenomenon of the electron beam in more detail, first, the electron beam scanned from the electron gun receives a Lorentz force while traveling toward the fluorescent screen inside the cathode ray tube, and its path is changed. For example, when an electron beam moves in a vertical direction (Y direction) of the fluorescent screen in a cathode ray tube in which the phosphor forming the fluorescent screen is a stripe type, the electron beam emits phosphors of the same color, so color purity problems do not occur. When the electron beam moves in the horizontal direction (X direction) of the fluorescent screen, the moved electron beam emits phosphors of different colors, causing color purity problems.

The horizontal component (X direction) component F _x of the Lorentz force causing the color purity problem in the above is represented by Equation 1 below.

Where e is the charge amount, v is the speed of the electron beam, B is the magnetic flux density, and the subscripts x, y and z represent the X, Y and Z directions, respectively.

In addition, the geomagnetic component affecting the cathode ray tube may be divided into a vertical component in a direction perpendicular to the ground (Y direction) and a horizontal component in a direction horizontal to the ground. The subdivision of the horizontal component of the geomagnetism acts in the so-called north-south direction (hereinafter referred to as NS direction) horizontal component acting in parallel with the tube axis of the cathode ray tube (hereinafter referred to as NS direction) and in a direction perpendicular to the tube axis (X direction). It can be classified into the so-called east-west direction (hereinafter referred to as EW direction) horizontal component.

In the conventional cathode ray tube, an inner shield, which is a magnetic shield member, is mounted on an assembly of a shadow mask and a mask frame so that the electron beam is not affected by the geomagnetism and mounted inside the cathode ray tube. In order to minimize the mis-landing phenomenon, a V-shaped notch is formed at the short side of the inner shield, or as shown in FIG. 7 or 8, the electron beams are formed at the long sides 60a and 64a of the inner shield 60 and 64. Long single or plurality of slots 60b and 64b are formed in parallel with the scanning direction.

However, the inner shields 60 and 64 having slots of such a shape mainly aim to reduce the miss landing amount of the electron beam due to the horizontal component of the EW direction of the geomagnetism. Landing amount was rather a problem to increase.

The present invention has been made to solve the above problems, the object of which is to minimize the effect of the horizontal magnetic force in the external magnetic field, such as geomagnetic field, in particular the tube axis direction (NS direction) to reduce the amount of miss landing of the electron beam It is to provide a cathode ray tube having a shield member.

1 is a cross-sectional view showing a cathode ray tube having a shield member according to the present invention.

2 is a perspective view showing a shield member according to an embodiment of the present invention.

FIG. 3 is a sectional view seen from the direction III-III of FIG. 2.

4 is a front view showing a shield member according to an embodiment of the present invention.

5 is a graph showing the distribution of the spatial magnetic field along the path of the electron beam in the cathode ray tube according to the present invention.

6 is a graph showing the distribution relationship between the slot position and the electron beam movement amount of the shield member according to the present invention.

7 is a front view showing a conventional shield member.

8 is a front view showing a conventional shield member.

* Description of the symbols for the main parts of the drawings *

20: Panel 20a: Screen portion

22: fluorescent screen 24: funnel

26: Neck 28: Deflection Device

30: electron gun 31: electron beam

32: color screening device 33: magnetic field

34: mask 36: frame

40: shield member 40a: long side portion

40c: slot 40d: flap

In order to achieve the above object, the present invention includes a panel having a screen portion on which a fluorescent screen is formed, and a side surface formed around the screen portion; A funnel connected to the panel and provided with a deflection device on an outer circumference thereof; A neck connected to the funnel and equipped with an electron gun for generating an electron beam scanned into the fluorescent screen therein; A color sorting apparatus mounted inside the panel to color-select the electron beam to reach a corresponding phosphor of the fluorescent screen; And a shield member arranged to be connected to the neck while being connected to the color screening device to shield the geomagnetism affecting the scanning trajectory of the electron beam, wherein the shield member is formed by a combination of a pair of long sides and short sides; At least one long slot is formed in the long side portion along the width direction (X direction) of the screen portion, and a cathode ray is formed on the panel side of the slot so that flaps are arranged on the inside of the shield member. Provide a coffin.

The shield member is preferably formed such that the slot and the flap correspond to each other on the pair of long sides facing each other.

Further, the width of the shield member in the tube axis direction Z of the cathode ray tube is H, and the distance from the panel side of the shield member in the tube axis direction Z to the slot is h, perpendicular to the tube axis direction Z. When the width of the shield member at the point where the slot is formed in one direction is W, and the long side length of the slot is w, the shield member is preferably formed by satisfying the following equation.

43 ≤ (h / H) × 100 ≤ 93, 50 ≤ (w / W) × 100 ≤ 93

On the other hand, in the cathode ray tube according to the present invention, the color screening device comprises a mask having a plurality of electron beam through holes and the shape of the major axis and the minor axis is set; And a pair of support members disposed corresponding to the long axis of the mask at predetermined intervals and coupled to the mask stretched in one of the long and short axes, and arranged to correspond to the short axis of the mask. It may include a frame consisting of a pair of rigid members to be fixed across both ends of the support member to maintain the tension applied to the mask.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a cross-sectional view showing a cathode ray tube having a shield member according to the present invention, Figure 2 is a perspective view showing a shield member according to an embodiment of the present invention.

As shown in FIG. 1, the cathode ray tube according to the present invention includes a panel 20 that forms a fluorescent screen 22 on an inner surface of the screen portion 20a and forms a side surface 20b around the screen portion 20a. And form an external appearance with a vacuum tube formed of a funnel 24 connected to the panel 20 and a neck 26 connected to the funnel 24, and the electron beam is formed on the outer circumference of the funnel 24 as usual. The deflecting device 28 for deflecting the laser beam is mounted and the electron gun 30 for generating the electron beam is mounted inside the neck 26.

In addition, a color screening device 32 for color-selecting a plurality of R, G, and B electron beams scanned by the electron gun 30 is mounted inside the panel 20. The mask 34 included in the color screening device 32 is formed of a tension mask type. That is, the mask 34 has a substantially rectangular shape in which a long axis and a short axis are set while having a plurality of electron beam through holes.

The mask 34 is fixed to the frame 36 that is tensioned and supported by the predetermined tension in the long axis or short axis direction, wherein the frame 36 is a support member disposed to face each other at a predetermined interval from each other And a rigid member 36b fixedly coupled to both ends of the support members 36a to form a rectangular frame together with the support members 36a.

The color screening device 32 configured as described above is disposed inside the panel 20 so that the mask 34 faces the fluorescent screen 22 and is substantially connected to the panel by a coupling means composed of a hook and a spring. 20) It is mounted inside.

On the other hand, the color screening device 32 is coupled to the periphery of the frame 36 in the direction toward the neck 26 and disposed in a space between the panel 20 and the neck 26 to scan the trajectory of the electron beam. Shield member 40 for shielding the geomagnetism affecting is installed.

As shown in FIG. 2, the shield member 40 is composed of a combination of a pair of long side portions 40a and short side portions 40b facing each other, wherein the long side portion 40a includes the screen portion. An elongated slot 40c disposed along the width direction (X direction) of the 20a is formed, and the slot 40c is approximately formed at one side of the long side portion 40a, for example, the panel side, into the slot 40c. A flap 40d having an area equal to the size of the flap is formed to hang inward of the shield member 40.

The slot 40c and the flap 40d of the shield member secure a portion as large as the slot 40c in the long side portion 40a in the shape of a rectangle when the shield member 40 is manufactured. Except for the panel side only, the remaining three sides may be cut and then folded by a predetermined angle toward the inside of the shield member 40.

On the other hand, the slot 40c and the flap 40d is preferably formed to correspond to each other in the pair of long side portion (40a).

FIG. 3 is a cross-sectional view taken from the direction of III-III of FIG. 2 to illustrate a process of changing a magnetic field by the slot and the flap.

As mentioned above, the electron beam 31 emitted from the electron gun 30 is changed by the Lorentz force while traveling inside the cathode ray tube toward the fluorescent screen 22, and in particular, the screen of the Lorentz force is changed. The width direction (X direction) component of the part 20a Under the force of, the movement path in the X direction is changed, that is, mislanded.

However, in the present invention, when the magnetic field causing the Lorentz force is distributed inside the shield member 40, the magnetic field distributed near the flap 40d is distributed along the arrangement direction of the flap 40d. The B _y component 33 of the present invention has a larger value than the conventional B _y component 35. In other words, in the orbit of the electron beam 31, the magnetic field on the orbit of the electron beam 31 in which the flap 40d is located becomes close to a direction perpendicular to the tube axis of the cathode ray tube, which is expressed by the above equation. Among the components of the Lorentz force expressed, it means that the component of B _y becomes large, and that means that the Lorentz force of the X direction is made smaller by the component of B _y that is increased.

4 is a plan view showing a shield member according to an embodiment of the present invention.

As shown in FIG. 4, the width of the shield member 40 in the tube axis direction (Z direction) of the cathode ray tube is H, and the distance from the panel side of the shield member 40 in the tube axis direction to the slot 40c. H, when the width of the shield member 40 at the point where the slot 40c is formed in a direction perpendicular to the tube axis is W, and the long side length of the slot 40c is w, the shield member 40 ) Is preferably formed by satisfying the following equation.

43 ≤ (h / H) × 100 ≤ 93, 50 ≤ (w / W) × 100 ≤ 93

Here, when the value of (h / H) x 100 is less than 43, it is difficult to expect the effect according to the present invention, and when it exceeds 93, manufacturing limitations follow.

In addition, when the value of (w / W) x 100 is less than 50, the long side length of a slot is small, and it is hard to expect the effect which concerns on this invention, and when it exceeds 93, a manufacturing limit follows.

That is, when the slot 40c and the flap 40d are formed in the long side portion 40a of the shield member 40, the effect according to the present invention can be maximized by forming the slot 40c and the flap 40d.

5 is a graph showing the distribution of the spatial magnetic field along the path of the electron beam in the cathode ray tube according to the present invention.

That is, it shows the magnetic flux density (B) with respect to the horizontal component of the geomagnetism according to the tube axis distance from the electron gun to the screen portion inside the cathode ray tube. For convenience, the left side on the X axis is in the necked direction of the cathode ray tube, The right side was viewed toward the fluorescent screen of the cathode ray tube and the distance on the axis of the tube on the X axis was shown as the starting point from the neck side. When showing the position of the shield member 40 according to the present invention on this graph, it is located between approximately 90mm to 230mm point, of which the area of the slot 40c and flap 40d is between about 120mm to 140mm It is located at.

As can be seen from the graph, on the shield member 40 of the present invention, when B _y distributed in the position where the slot (and flap) region is located is conventional (the slot and the flap according to the present invention are not provided in the shield member). Since it has a larger value than B _{y of} ), thereby reducing the overall amount of the Lorentz force, thereby reducing the mislanding phenomenon of the electron beam.

Example 1

Electron beam when a conventional shield member is employed for a 22 "cathode ray tube of a tension mask type under the conditions of horizontal geomagnetic (B _h ) 300 mG and vertical geomagnetic (B _v ) 380 mG and when the shield member according to the present invention is employed. The amount of movement was measured.

That is, as the distance from the center of the screen to the edge is relatively shown, the vertical point of the screen (15 mm away from the vertical edge of the effective screen) to zero, and the diagonal point of the screen (from the vertex of the effective screen). Horizontal and vertical points 15 mm apart) were 100%, and Table 1 shows the amount of movement of the electron beam due to the horizontal component in the NS direction and the vertical points of the screen and 63%, 84% and 100% (diagonal points) therefrom. The movement amount of the electron beam due to the horizontal component in the EW direction is measured and shown.

Prior art The present invention Position on screen 0 63% 84% 100% 0 63% 84% 100% Electron Beam Shift [μm] 27 27 22 12 25 26 21 10

As shown in Table 1, it can be seen that the movement amount of the electron beam in the overall area is reduced, and thus the miss landing amount of the electron beam is reduced.

Example 2

In FIG. 6, (w / W) x 100 is fixed to 70, and (h / H) x 100 is changed from 20 to 80 while measuring the amount of electron beam movement due to the horizontal component of the N-S direction of the geomagnetism.

The movement amount of the electron beam is a relatively represents the movement amount of the electron beam measured by employing the shield member according to the present invention when the conventional movement amount is 100% at the same point. That is, when the value is less than 100%, the miss landing phenomenon of the electron beam is improved.

It can be seen from FIG. 6 that the amount of miss landing of the electron beam is greatly reduced from the value of (h / H) × 100 of 43% or more.

In the above description, the tension mask type cathode ray tube has been described, but the shield member according to the present invention may be applied to a cathode ray tube of a formed mask type.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications and changes can be made within the scope of the claims and the detailed description of the invention and the accompanying drawings. Naturally, it belongs to the scope of the invention.

As described above, according to the cathode ray tube provided with the shield member according to the present invention, a slot and a flap are formed in the long side portion of the shield member in a direction perpendicular to the scanning direction of the electron beam. By reducing the amount of landing there is an effect that can improve the color purity characteristics.

Claims (4)

A panel having a screen portion on which a fluorescent screen is formed and a side surface formed around the screen portion; A funnel connected to the panel and provided with a deflection device on an outer circumference thereof; A neck connected to the funnel and equipped with an electron gun for generating an electron beam scanned into the fluorescent screen therein; A color sorting apparatus mounted inside the panel to color-select the electron beam to reach a corresponding phosphor of the fluorescent screen; And Shield member for shielding the geomagnetism which is connected to the color sorting device and disposed toward the neck to affect the scanning trajectory of the electron beam Including, The shield member is formed by a combination of a pair of long side portions and short side portions, and at least one long slot is formed in the long side portion along the width direction (x direction) of the screen portion, and the shield is formed on the panel side of the slot. A cathode ray tube in which a flap is formed which is arranged to extend inwardly of the member. The method of claim 1, Cathode ray tube formed so that the slot and the flap correspond to each other of the pair of long sides facing each other. The method of claim 1, The width of the shield member in the tube axis direction (z direction) of the cathode ray tube is H, and the distance from the panel side of the shield member in the tube axis direction (z direction) to the slot is h, and in the tube axis direction (z direction). The shield member is formed when the width of the shield member at the point where the slot is formed with respect to the vertical direction is W, and the long side length of the slot is w, the shield member is formed by satisfying the following equation. 43 ≤ (h / H) × 100 ≤ 93, 50 ≤ (w / W) × 100 ≤ 93 The method of claim 1, wherein the color screening device A mask having a plurality of electron beam passing holes and having a shape in which a major axis and a minor axis are set; And A pair of support members disposed corresponding to the long axis of the mask at predetermined intervals and coupled to the mask stretched in one of the long and short axes, and the support being disposed corresponding to the short axis of the mask; A frame composed of a pair of rigid members fixed across both ends of the members to maintain tension applied to the mask; Cathode ray tube comprising a.