KR20020094300A - Shadow mask supporting structure of CRT - Google Patents

Abstract

PURPOSE: A shadow mask support structure for a CRT is provided to reduce overcompensation of corner spring with respect to the change of external temperature of the CRT. CONSTITUTION: A CRT comprises a funnel; a panel coupled to the funnel, and which has an inner surface on which a phosphor screen is formed; an electron gun mounted in the funnel, and which emits electron beams toward the phosphor screen; a deflection yoke for deflecting electron beams emitted from the electron gun; a shadow mask mounted at the inner surface of the panel; a support frame for supporting the shadow mask; and a corner spring(20) constituted by a fixed piece(22) welded to the support frame, and a movable piece(25) having an end attached to the fixed piece and the other end attached to the panel through a stud pin. The movable piece of the corner spring, includes an inner plate(251) having a low coefficient of thermal expansion and an outer plate(252) having a high coefficient of thermal expansion.

Description

Shadow mask supporting structure of CRT

The present invention relates to a shadow mask support structure of a CRT, and more particularly, to a corner spring for supporting a shadow mask in a CRT.

In general, the CRT is fused and bonded to the funnel 10 and the flat panel 12 having the fluorescent film on the inner side of the funnel 10 and the funnel 10 as shown in FIG. And a deflection yoke (not shown) for deflecting the electron beam 14 emitted from the electron gun 14 and the electron beam emitted from the electron gun 14.

Here, a shadow mask 16 is mounted on the inner surface side of the panel 12 to color-select the electron beam emitted from the electron gun 14 so as to contact the fluorescent film. The shadow mask 16 has a plurality of microslot shapes. As the thin film on which the electron passing hole 16a is formed, it is mounted in a structure supported by the support frame 18.

In addition, the support frame 18 is supported by a corner spring 20 attached to the edge of the panel 12, the corner screen 20 is a plate-like fixing piece 22 as shown in FIG. And a movable piece 24 having a bent structure welded to the fixed piece 22, and the fixed piece 22 is attached to the support frame 18 by welding or the like, and the movable piece 24. It is attached to the inside of the panel 12 in such a manner as to be fixed by the stud pins 30.

According to the CRT as described above, power is applied to the cathode of the electron gun 14 to generate an electron beam, and the generated electron beam is accelerated and focused while passing through the accelerating electrode and the focusing electrode, and then the shadow mask is deflected by the deflection coil. The image is realized by emitting the phosphor of the fluorescent film by passing through (16) and impinging on the fluorescent film.

Meanwhile, only a part of the electrons emitted from the electron gun 14 pass through the shadow mask 16 to reach the fluorescent film through the electron passing hole, and the rest hits the shadow mask 16.

According to the so-called electron collision phenomenon, the kinetic energy of the electrons strikes the shadow mask 16, thereby converting it into thermal energy, thereby causing a doming phenomenon in which the metal shadow mask 16 is thermally expanded. As shown in FIG. 3, as the shadow mask 16 is thermally expanded and expanded, the electron passing hole 16a moves by a predetermined displacement ΔM.

Therefore, as a result, the electron passing hole 16a deviates from the correct scanning path (solid line display) of the electron beam, and a miss-landing phenomenon occurs in which the electron beam does not pass through the electron passing hole 16a correctly. Done.

According to the mislanding phenomenon, since the color purity of the image embodied in the panel 12 is reduced, a dominant compensation action for preventing the mislanding phenomenon due to the displacement of the electron passing hole 16a is also performed. The support frame 18 in contact with the 16 is inflated by the heat transferred from the shadow mask 16 and is made by the corner spring 20 which is pressed by the inflating the support frame 18.

That is, the corner spring 20 is urged by the support frame 18 expanded by the predetermined displacement ΔF, thereby narrowing the distance between the stationary piece 22 and the movable piece 24, and consequently the movable piece 24. The support frame 18 is lifted by being elastically extended by this constant displacement ΔS.

In addition, the shadow mask 16 along with the support frame 18 is also moved by a certain displacement ΔS so that the position of the electron passing hole 16a is placed on the correct scanning path of the electron beam, thereby preventing mis-landing. .

The degree of displacement of the electron passing hole 16a due to the chariot collision is determined by the thermal expansion coefficient of the shadow mask 16 and the temperature change amount and length of the shadow mask 16, and the degree of displacement of the support frame 18. Is determined according to the thermal expansion coefficient of the support frame 18, the temperature change amount and the length, and the compensation amount of the corner spring 20 is the angle between the fixed piece 22 and the movable piece 24 and the electron passing hole 16a. The degree of displacement and the degree of displacement of the support frame 18 are set as a reference.

In addition, in the structure of the general curved CRT, the corner spring 20 is large at the edge (curved portion) of the shadow mask 16 because the displacement degree of the electron passing hole 16a due to the electron collision phenomenon is larger than the other portions (flat portion). The amount of displacement of the electron passing hole 16a occurring at the edge of the shadow mask 16 may also be taken into account in setting the amount of compensation by the shadow mask 16.

In addition, the temperature change amount of the shadow mask 16 due to the electron collision phenomenon is about 70 ℃, the temperature change amount of the support frame 18 is about 47 ℃, the temperature change amount of the shadow mask 16 and the support frame 18 Since there is a significant difference, the compensation amount of the corner spring 20 according to the ambient temperature is based on the room temperature.

According to this conventional technique, the compensation amount of the corner spring 20 exceeds the degree of displacement of the electron passing hole 16a with respect to the flat portion of the shadow mask 16 on the basis of the compensation amount setting criteria of the corner spring 20 as described above. This results in so-called overcompensation.

In addition, since the temperature change amount of the shadow mask 16 is about 1.5 times larger than the temperature change amount of the support frame 18, the result of shifting the entire doming curve as shown in FIG. That is, even when the temperature of the CRT inner part changes due to the external temperature of the CRT being changed, the overcompensation phenomenon of the corner spring 20 is caused.

As a result of the overcompensation caused by the temperature change of the CRT, the electron passing hole 16a is deviated from the correct scanning path of the electron beam by a certain displacement ΔB, and the electron beam passes through the electron passing hole 16a. As a result of the mis-landing phenomenon that does not pass correctly, the color purity of the image implemented in the panel 12 is reduced. Therefore, in the conventional CRT, in order to solve these problems, the pitch of the shadow mask 16 is increased, A method of reducing the light emitting area of the panel 12 has been used.

However, in recent years, as the TV is enlarged and the image quality of high definition, high brightness, and high resolution due to digital broadcasting is required, the shadow tube 16 has a small pitch and the light emitting area of the panel 12 is wide. Since this is required, a problem arises in that the conventional method cannot maintain the performance stability of the CRT against external temperature changes.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a shadow mask support structure of a CRT to reduce an overcompensation amount of a corner spring against a change in CRT.

1 is a cross-sectional view showing the structure of a typical CRT.

2 is a schematic cross-sectional view showing a shadow mask support structure of a CRT according to the prior art.

Figure 3 is a state diagram showing the operation of the corner spring in the shadow mask support structure of the CRT according to the prior art.

Figure 4 is a graph showing the change in the dominant amount according to the temperature change outside the CRT in the prior art.

Figure 5 is a state diagram showing the overcompensation operation of the corner spring in the prior art.

Figure 6 is a cross-sectional view showing the structure of the corner spring applied to the shadow mask support structure of the CRT according to an embodiment of the present invention.

7 is a state diagram showing the operation of the corner spring according to an embodiment of the present invention.

8 a and b is a graph showing a change in the dominant amount change according to the prior art and the change in the dominant amount according to an embodiment of the present invention, when the external temperature of the CRT changes within a specific range.

<Explanation of symbols for the main parts of the drawings>

10: funnel 12: panel

14: electron gun 16: shadow mask

16a: electron passing hole 18: support frame

20: corner spring 22: fixing piece

25: movable piece 251: inner plate

252: outer shell 30: stud pin

The shadow mask support structure of the CRT provided to achieve the above object is a bimetal structure in which the movable plate of the corner spring is overlapped with the inner plate and the outer plate having different coefficients of thermal expansion, and the inner plate of the movable plate is made of a low expansion material having a low coefficient of thermal expansion, The outer plate is made of a high expansion material having a high coefficient of thermal expansion.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to FIGS. 6 to 8, and the same reference numerals will be given to the same parts as the conventional configurations of the present invention.

The shadow mask support structure of the CRT according to an embodiment of the present invention is fixed to the support frame 18, the fixing piece 22 and the fixing piece 22 is attached to one end and the other end of the panel by the stud pin 30 It comprises a corner spring (20) consisting of a movable piece (25) attached to (12), as shown in FIG. 6, the movable piece (25) of the corner spring (20) has an inner plate having different thermal expansion coefficients ( 251 and the outer plate 252 is formed of an overlapping bimetal structure.

The inner plate 251 refers to a part in contact with the fixing piece 22, the outer plate 252 is a part configured to be in contact with the inner plate 251 and opposite the fixing piece 22, the inner plate 251 and the outer plate 252 is It is composed of a so-called low expansion material having a low thermal expansion coefficient and a high expansion material having a high thermal expansion coefficient, respectively.

Herein, the coefficient of thermal expansion of the outer plate 252 is 10 × 10 so that the ratio of the coefficient of thermal expansion of the materials constituting the outer plate 252 and the inner plate 251 is greater than 2.5 and less than 9.^-6To 18 × 10^-6/ ℃ The coefficient of thermal expansion of the inner plate 251 is 2 x 10^-6To 4 × 10^-6It is desirable to be / ℃, which is when the ratio of the coefficient of thermal expansion of the outer plate 252 and the inner plate 251 is less than 2.5, the amount of compensation for the change in the external temperature of the CRT becomes insignificant, and in the case of 9 or more causes overcompensation Because.

In addition, in configuring the outer plate 252 and the inner plate 251 of the movable piece 25, the thickness thereof is preferably 0.3 to 0.6 mm, which is 0.3 mm to the thickness of the outer plate 252 and the inner plate 251. If it is thinner than mm, high precision is required in the process of manufacturing and joining each plate, and as a result, the machining productivity of the corner spring 20 decreases. If the thickness of each plate is thicker than 0.6 mm, the movable piece 25 is used. This is because the structural strength of the support frame 18 becomes difficult to attach and detach by increasing.

Referring to the operation of the corner spring according to an embodiment of the present invention as described above are as follows.

First, when the external temperature of the CRT varies, the electron passing hole 16a of the shadow mask 16 is moved by a certain displacement ΔM as shown in FIG. 7, and the support frame 18 also has the shadow mask 16. It is moved by a certain displacement (ΔF) by being pressed by), the displacement (△ S) according to the compensating action of the corner spring 20 is also induced.

In addition, when the temperature outside the CRT varies, overcompensation is performed to cause overdisplacement ΔSt of the shadow mask 16 from which the electron passing hole 16a deviates from the correct scanning path of the electron beam.

However, due to the structure of the movable piece 25 of the corner spring 20, the shadow mask 16 is displaced in the opposite direction by the relative contraction action of the inner plate 251 with respect to the outer plate 252, that is, the reverse compensation action. By moving as much as possible, the amount of change in the position of the electron passing hole 16a due to the overcompensation action is attenuated.

As described above, the shadow mask support structure according to the embodiment of the present invention corresponds to the change in the dominant amount of the shadow mask 16 corresponding to the change in the external temperature of the CRT. It can be seen that when the external temperature is changed from -10 ° C to 45 ° C, it becomes about 17 μm (see b of FIG. 8).

Under the same external temperature change condition, since the change in the domming amount of the corner spring 20 according to the prior art is about 30 μm (see FIG. 8A), it can be seen that according to the embodiment of the present invention, the domming amount is reduced by 43%. have.

In forming the movable piece 25 of the corner spring 20 applied to the test, sus603 0.5t was used as the material of the outer plate 252, and invar, which is a kind of invariable steel, as the material of the inner plate 251. 0.5t was used.

The coefficient of thermal expansion of sus603, which is the material of the outer plate 252, is 11.5 ± 5 × 10 ⁻⁶ / ° C., and the coefficient of thermal expansion of invar, which is the material of the inner plate 251 is 2.5 ± 5 × 10 ⁻⁶ / ° C., with the outer plate 252. The coefficient of thermal expansion of the inner plate 251 was set to be about 4.6.

As described above, according to the shadow mask support structure of the CRT according to the present invention, the overcompensation of the corner springs with respect to the external temperature change of the CRT is reduced, thereby satisfying the conditions according to the trend of larger and higher CRTs and the stability of the CRT. There is an advantage that can be maintained.

Claims (4)

Funnel and, A flat panel fusion-bonded with the funnel and provided with a fluorescent film on an inner surface thereof; An electron gun mounted in the funnel to emit an electron beam toward a fluorescent film; A deflection yoke for deflecting the electron beam emitted from the electron gun, A shadow mask mounted on the inner surface side of the spring panel to color-select the electron beam emitted from the electron gun to reach the fluorescent film; A support frame for supporting the shadow mask; Corner spring consisting of a fixed piece to be welded to the support frame and the movable piece is attached to one end and the other end is attached to the panel by a stud pin In a tube containing a; The movable piece of the corner spring A CRT tube having a bimetal structure in which an inner plate of a low expansion material having a low coefficient of thermal expansion and an outer plate of a high expansion material having a high thermal expansion coefficient are stacked. The method of claim 1, wherein the movable piece The coefficient of thermal expansion of the outer shell and inner shell is more than 2.5 and less than 9, characterized in that the CRT. The method of claim 1, wherein the movable piece The coefficient of thermal expansion of the shell is 10 × 10^-6To 18 × 10^-6/ ℃ ego, The coefficient of thermal expansion of the inner plate is 2 × 10 ^-6 ~ 4 × 10 ^-6 / ℃. The method of claim 1, wherein the movable piece The thickness of the outer shell and inner shell is 0.3 ~ 0.6mm, respectively.