KR100370734B1 - Color cathode ray tube - Google Patents

Abstract

PURPOSE: A color cathode ray tube is provided to shield the earth magnetic field and perform a function of a contact spring by forming a plurality of holes on an inner shield. CONSTITUTION: A color cathode ray tube includes a neck portion having a panel(51) and an electron gun, a funnel(52), a shadow mask for performing a dichroic function, a frame(56) for supporting the shadow mask, and an inner shield(59) installed at a read part of the frame. The inner shield includes one or more holes and a support section(57). The support section is connected to an edge of the hole and an inner surface of the funnel. The holes are formed at a long side portion, a short side portion, and an edge portion of the inner shield. A concave portion and a convex portion are selectively formed on the support section which comes in contact with the inner face of the funnel.

Description

Color cathode ray tube

The present invention relates to a color cathode ray tube, and more particularly, to prevent the screen from being formed on the panel face surface due to internal discharge of the CRT when the power is turned on.

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

As shown, a panel 1 having a fluorescent film formed on its inner surface and a funnel 2 coated with conductive graphite on its inner surface are sealed together by fusion glass in a furnace at about 450 ° C. and the neck portion 3 of the funnel. An electron gun 7 for generating an electron beam is mounted on the inside of the panel, and a shadow mask 4, which is a color-selective electrode, is supported by the frame 5 on the inside of the panel, and a deflection yoke that horizontally orients the electron beam on the outer circumferential surface of the funnel. (8) is attached.

The color CRT configured as described above receives hot electrons from the cathode of the electron gun when the image signal is input to the electron gun, and the emitted electrons are accelerated and focused toward the panel by the voltage applied from each electrode of the electron gun.

At this time, the traveling path of the electron (9) is adjusted by the magnetic field of the magnet mounted on the neck of the panel, and the adjusted electron beam is scanned on the inner surface of the panel by the deflection yoke (8). Color selection is performed while passing through the slots of the shadow mask coupled to the inner frame, and the selected pendulum beam collides with each fluorescent film on the inner surface of the panel to emit light to reproduce the image signal.

In order to prevent the electron beam from being deflected due to the influence of geomagnetism when the electron beam passes through the slot of the shadow mask to reach the fluorescent film, the geomagnetic shielding inner shield (hereinafter referred to as an inner shield; INNER SHIELD) (6) is attached.

As shown in FIG. 2, the cathode ray tube 3 formed by being fused to the panel 1 and the funnel 2 is applied so that a high voltage is applied to the cathode ray tube through the anode 6 of the cavity so that a screen can be formed. An inner conductive film 4 and an outer conductive film 5 having electrical conductivity are formed inside and outside the funnel 2, and the conductive film set with the glass in between serves as a capacitor.

Conventionally, a mixture of graphite, an adhesive (water glass), and a dispersant is used to form a conductive film, and recently, metal oxides are added for the purpose of increasing electrical resistance.

And the following application method is proposed as a method of forming a conductive film conventionally.

① How to apply with a brush or sponge

② Coating method by spraying

③ deposition method

④ Flow coating method

Recently, among these methods, as a method of applying to the inner surface of the funnel 2, a flow coating method in which a conductive film is easily applied in one operation is generally widely used, and a method of applying to the outer surface of the funnel with a brush or a sponge is generally used. The coating method is generally widely used.

In more detail, the role of each component of the conductive coating liquid will be discussed. As a matter of course, the electric current applied through the cavity flows well to the electron gun 1 along the conductive coating.

The adhesive also uses potassium silicate or sodium silicate and allows graphite and metal oxides to adhere well to the funnel glass surface.

Dispersants help to disperse graphite and metal oxides well in water glass containing pure water.

Metal oxide added with graphite serves to increase the electrical resistance value as a non-conductor, and uses iron oxide (Fe ₂ O ₃ ) or titanium oxide (TiO ₂ ).

However, in the case of the conductive film not using the metal oxide, when the foreign substance is present in the electron gun 7 part of the cathode ray tube, an electrical spark occurs and at this time, a high current of about 600 to 1000 A is generated, Problems that damage the electrical circuit components of the conductive film and the cathode ray tube occur.

In order to solve this problem, iron oxide and titanium oxide, which are insulators, are added to a conductive film based on a mixture of graphite, an adhesive, and a dispersant.

In order to reduce the overcurrent, the mixed iron oxide and titanium oxide have a specific gravity higher than that of graphite, so when the conductive coating liquid is simply left or the conductive coating liquid is applied to the funnel 2, the iron oxide and titanium oxide sink and the graphite layer is lowered. Floating delamination may be achieved.

And if the graphite layer is applied in the state of floating up and dried, the electrical conductivity is improved, the resistance value is lowered, thereby causing the same problem as when the metal oxide is not added.

In addition, it takes a lot of time to redistribute the submerged metal oxide, the dispersibility of the metal oxide is also worse, and there is also a problem that the conductive film becomes uneven.

On the other hand, the conventional method of coating with a brush or sponge has a problem that the process is complicated, the coating film is not uniform, and the spray coating method has a problem that the film stain occurs depending on the dispersion state of the graphite slurry.

In addition, in the case of the deposition method or the flow coating, the coating film is easily formed in the portion where the coating film should not be formed, and the process is complicated to remove the formed film, and the loss of material is also caused, and the paint on the inner surface of the funnel 2 is deposited on the inner surface of the funnel 2. The paint flowing down because it flows from the upper part to the lower part of the funnel (2) becomes thinner at the upper part of the funnel (2) to increase the electrical resistance, and at the yoke part of the funnel, the flow rate becomes weaker, so the thickness becomes thicker and the electrical resistance becomes lower and the neck part In the coating liquid containing graphite is drawn out, the electrical resistance is lower, in particular, the coating thickness is changed according to the viscosity of the coating liquid and nonuniform electrical resistance is formed on the inner surface of the funnel.

In particular, when the electrical resistance is higher than 4kΩ at the contact spring contact part which is attached to the frame or inner shield of the upper part of the coating film formed on the inner surface of the funnel and is in contact with the conductive coating film on the inner surface of the funnel, the cathode ray tube is turned on. When discharge occurs due to the potential difference between the spring and the conductive film, the conductive film at the spring contact part is destroyed and disappeared, so that the high voltage applied through the cavity of the cathode ray tube does not flow uniformly inside the funnel, resulting in a fatal product defect. Occurs frequently.

In order to solve this problem, Japanese Patent Application Laid-Open No. JP58-176854 designs a conductive layer having a high resistance and high mechanical strength as the first layer and a low resistance and low mechanical strength as the second layer at the contact portion between the conductive layer and the contact spring. The conductive layer having was formed.

In addition, JP51-29080, JP53-142862, JP54-858, and JP54-81770 attach contact springs to the shield side wall to connect the cathode ray tube conductive film so that the voltage applied from the cavity flows.

JP58-176854 added more metal oxides, such as TiO ₂ and FeO ₃ , to increase the resistance and high mechanical strength, and increased the amount of graphite than the metal oxide to add low mechanical strength and low resistance in the second layer. As a result of the more use, the low electrical resistance of the second layer may result in good electrical conduction at the contact spring and the contact area, but the strength of the conductive film is weak due to the weak strength of the conductive film. When there is a physical impact between the inside and the outside, the strength of the conductive film is so weak that the conductive film is easily peeled off, so that the debris or debris of the conductive film blocks the shadow mask hole inside the cathode ray tube, or enters between electron guns, resulting in an electrical spark caused by a small electrode gap. There is.

Also, in JP51-29080, JP53-142862, JP54-858, and JP54-81770, there are problems in the process of attaching contact springs for electrical conduction and cost increase due to the use of contact springs. As a result, the strength may vary, resulting in a problem of contact failure.

Therefore, when the cathode ray tube is turned on, the discharge occurs due to the potential difference between the spring and the conductive layer, and the conductive layer at the spring contact portion is destroyed so that the high voltage applied through the cavity of the cathode ray tube does not flow uniformly inside the funnel. As a result, there is a problem in that a fatal product defect rate, in which a screen is not formed, increases.

Therefore, in view of the conventional problem, the present invention designs a plurality of holes connected to the inner shield without attaching a contact spring separately and a part of the hole in the inner shield is not completely cut, and a metal end corresponding to the cut part of the hole. The support piece 57 of the portion is in contact with the conductive film formed on the funnel to serve as a contact spring, so as to simultaneously serve as a geomagnetic shield and a contact spring.

Hereinafter, the configuration and operation of the present invention will be described in detail.

The panel 51 is sealed in a panel 51 coated with a fluorescent film and a funnel 52 coated with an internal paint, and a neck portion 53 is provided at the rear of the funnel 52, and the neck portion 53 has an electron gun 60. Inside the panel 51, a shadow mask, which is a color-selective electrode, and an inner shield 59 having a geomagnetic shielding function are supported on the frame 56, and an electron beam is left and right on the outer circumferential surface of the funnel 52. In a colored cathode ray tube with a deflecting yoke,

The voltage supplied from the anode 58 of the cavity flows well into the cathode ray tube to the conductive film formed on the inner surface of the funnel 52 without attaching a contact spring in contact with the conductive film to prevent destruction of the conductive film due to discharge. A plurality of holes are formed in the inner shield 59, and a part of the holes are not completely cut, and contact with the conductive film 61 formed in the inner shield 59 to serve as a contact spring, thereby serving as a geomagnetic shield and a contact spring. A support piece 57 can be provided at the same time.

Here reference numeral 55 is a spring.

Specifically, as shown in FIG. 3, the contact spring is formed by extracting several portions from the corners that are bent in order to be divided into the long side and the short side of the inner shield 59 to form a contact spring, and at the end of the inner shield. Protruding grooves or uneven portions of the cut holes are cut in the longitudinal direction of the holes so that the grooves or uneven portions are formed in the outward direction and then the end portions opposite to the protruding grooves or the uneven portions are not cut completely. It is configured to function as a contact spring by making contact with the inner surface.

The width of the hole is 0.1mm or more, preferably 5mm or more. If it is 0.1mm or less, it is difficult to make grooves or unevenness, and even if it is in contact with the conductive film formed on the inner surface of the funnel, the contact is easily dropped by vibration or shock. The metal part of the hole in contact with the breakdown and the conductive film may be melted away by heat during high-pressure discharge.

The length of the hole is 0.5 cm or more, preferably 3 cm or more, and more preferably 5 cm or more.

If it is shorter than 0.5 cm, the metal part of the cut hole is hard to come into contact with the conductive film formed on the inner surface of the funnel.

The shape of the hole is rectangular or right triangle or rounded right triangle or rounded rectangle or oval or round or trapezoidal polygon or rectangular or right triangle or rounded end triangle with long or wavy part Or the corner portion is a polygon of rounded rectangle or oval or circle or trapezoid shape.

The thickness of the inner shield 59 is 0.05 mm or more, preferably 0.1 mm or more, and more preferably 0.15 mm or more.

If it is thinner than 0.05mm, it is difficult to manufacture the inner shield shape, and even if it is manufactured, the contact film is likely to fall off due to vibration or shock when the metal of the hole part contacts the conductive film formed on the inner surface of the funnel. Easy to destroy

The effects of the present invention configured and acted as described above are as follows.

By designing a plurality of holes in the inner shield without attaching a contact spring in contact with the conductive film formed on the inner surface of the funnel, one part of the hole is connected to the inner shield and the other part of which the protruding unevenness or groove is formed on the inner surface of the funnel. Because it acts as a contact spring by contacting the formed conductive film, even if the electrical resistance of the conductive film is high, contact failure does not occur due to vibration or shock, so that the potential difference between the spring and the conductive film is caused when the cathode ray tube is turned on. Due to the generated discharge, the conductive film on the spring contact part is destroyed and disappeared, and the high voltage applied through the cavity of the cathode ray tube does not flow uniformly inside the funnel, which prevents fatal product defects in which the screen is not formed. Quality improvement, process shortening and cost It is advantageous for saving.

1 is a schematic view of a conventional color cathode ray tube.

2 is a schematic view of a conventional color cathode ray tube.

3 is a schematic diagram of a color cathode ray tube of the present invention.

4 is an enlarged cross-sectional view of part A of FIG.

5 is a schematic diagram of another embodiment of the present invention.

6 is an enlarged cross-sectional view of portion B of FIG.

7 is a comparison diagram.

*** Explanation of symbols for main symbols in the drawings ***

51: Panel 52: Funnel

56 frame 57 support piece cut from inner shield hole

58: cavity anode 59: inner shield

60: electron gun 61: panel inner conductive film

Claims (6)

A funnel having a panel coated with a fluorescent film and a neck portion equipped with an electron gun, and having a built-in paint applied thereto, a shadow mask disposed in the front of the panel and performing color discrimination, a frame supporting the shadow mask, and the frame In the color cathode ray tube comprising an inner shield mounted to the rear of the, At least one hole is formed in the inner shield, and one side of the color cathode ray tube, characterized in that the support piece is provided in contact with the edge of the hole and the other side in contact with the inner surface of the funnel. The method of claim 1, And a plurality of holes formed in at least one side of a long side portion, a short side portion, and a corner portion of the inner shield. The method of claim 1, A color cathode ray tube comprising a yaw and an iron portion selectively formed on a side of the support piece in contact with the inner surface of the funnel. The method of claim 1, The hole is a color cathode ray tube comprising a rectangular polygonal shape. The method of claim 1, The hole is a color cathode ray tube further comprises one provided with at least one of a circle and an ellipse. The method of claim 1, The support piece is a color cathode ray tube, characterized in that formed by bending the cut portion around the uncut portion in a cut state except a portion of the hole.