JP3362946B2 - Glass bulb for cathode ray tube - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glass bulb for a cathode ray tube (CRT) used in a television or the like, and more particularly to a strengthened structure of a glass panel constituting a display screen side thereof. Things. 2. Description of the Prior Art Cathode ray tubes or the like having a color selecting, the skirt portion of the edge of the face portion constituting the glass panel display screen, a metal for the purpose of fixing the shadow mask or aperture grille stud pins embedded in and is soluble adhesive fixed to the glass. Such glass panel portion stud pin is embedded situations, fever or in the polishing step of sealing the junction surface of the funnel portion, the heating operation for the gas component evaporated in the exhaust process at the time of sealing, or glass In a heating step or the like for welding the sealant, a high temperature state occurs and a large temperature change occurs. When subjected to such a temperature change, since the amount of expansion and contraction differs due to the difference in the coefficient of thermal expansion between the metal stud pin and the glass material, a large thermal stress is generated between the two and the glass panel portion is caused by a tensile stress on the glass material. Could be destroyed. In order to cope with such a problem, conventionally, a fillet is formed by melting a glass material along a periphery of a stud pin at a boundary between the stud pin and the glass. A method for reducing the concentration of stress on the boundary between them has been used. [0004] However, the relaxation of the stress concentration by the conventional fillet alone cannot sufficiently suppress the thermal stress and cannot sufficiently prevent the glass breakage in the stud pin embedded portion. Was. The present invention has been made in view of the above-mentioned drawbacks of the prior art, and has as its object to provide a glass bulb for a cathode ray tube in which glass breakage due to thermal stress in a stud pin embedded portion is reliably prevented. In order to achieve the above object, a glass bulb for a cathode ray tube according to the present invention comprises a substantially rectangular face portion constituting a display screen and a substantially peripheral portion of the face portion from a peripheral portion thereof. A glass panel portion comprising a skirt portion extending in a vertical direction, a funnel-shaped funnel portion hermetically joined to the glass panel portion, and a neck portion at the base of the funnel portion for storing an electron gun. In the glass bulb for a cathode ray tube, wherein a metal stud pin is fixed to the skirt portion, a compression stress layer is formed on a glass member around the stud pin. [0007] The compressive stress layer having a predetermined stress value cancels the tensile stress on the glass due to the temperature change in the thermal process, thereby preventing breakage. FIG. 2 is a sectional view of a cathode ray tube for television to which the present invention is applied. The cathode ray tube 1 basically includes a glass panel portion 3 on the image display screen side, a funnel-shaped funnel portion 4 hermetically joined to the glass panel portion 3, and a neck portion 5 containing an electron gun. And a glass bulb 2 composed of Glass panel 3
Is a substantially rectangular face portion 7 constituting an image display surface.
And a skirt portion 6 extending substantially vertically from the peripheral portion of the face portion 7. An explosion-proof reinforcing band 8 is wound around the outer periphery of the skirt portion 6 to maintain panel strength and prevent scattering at the time of breakage. On the inner surface side of the face portion 7, a fluorescent film 12 that emits fluorescence by irradiating an electron beam from an electron gun and an aluminum film 13 for preventing return of the fluorescent light from the fluorescent film 12 are laminated, and further on the inner side. A shadow mask 14 for defining the irradiation position of the electron beam is provided. The shadow mask 14 is formed by the stud pins 15 on the skirt 6.
It is fixed to the inner surface of. [0010] Such a glass panel portion 3 includes a sealing portion 1.
The sealing member is sealed to the funnel portion 4 by a sealing agent such as a frit sealing agent or a solder glass provided at the bottom. An inner coating 16 is provided on the inner side of the funnel portion 4 to prevent the shadow mask 14 from being highly charged by an electron beam and to conduct conductive grounding to the outside. FIG. 1 is a detailed view of a stud pin driving portion of a glass panel portion of a cathode ray tube according to the present invention. After the forming process of the glass panel portion 3, on the inner surface of the skirt portion 6 (see FIG. 2), a stud pin made of a metal such as a Cr-Fe alloy or 18% Cr and having an expansion coefficient substantially equal to that of glass is provided. 15 is embedded. In addition, the surface of the stud pin 15 usually has Cr ₂ O ₃ , FeO.Cr ₂ O ₃
Is formed. The stud pin 15 is a stepped cylindrical shape, the ends of the thick-diameter cylinder is inserted into soluble adhesive fixing in the glass material of the skirt portion 6. A fillet 25 made of a glass material is formed along the embedded boundary between the outer peripheral surface of the stud pin 15 and the glass material.
The fillet 25 suppresses stress concentration on the boundary between the stud pin 15 and the glass. Further, in the present embodiment, a compressive stress layer 24 is formed in the buried portion of the stud pin 15 (particularly around the portion where the fillet 25 is formed). It is desirable that the stress value of the compressive stress layer 24 be in the range of 40 to 200 kg / cm ² . If the stress value is less than this, sufficient strength cannot be obtained with respect to the tensile stress generated in the heating step, and the purpose of preventing glass breakage is not sufficiently satisfied. If the stress value is larger than this, a tensile stress of about 1/2 is generated inside the glass corresponding to the surface compressive stress.
On the contrary, the glass is easily broken. [0013] Such compression stress layer 24 may be formed after forming a glass panel portion, which is cooled to contract, the physical strengthening method of forming a compressive stress layer on the surface. This physical enhancement will be further described. When the glass is rapidly cooled from a high temperature region near the softening point, the surface rapidly shrinks and solidifies, but the inside still retains sufficient fluidity and remains expanded, and the temporary strain is instantaneously relaxed. Upon further cooling, the interior also tends to shrink, but its movement is limited by the presence of a solidified surface layer. As a result, when the temperature of the glass drops to room temperature and reaches a sufficient equilibrium state, a large compressive stress layer is formed on the surface and a tensile stress layer is formed inside, and remains as residual stress. At this time, the magnitude of the generated stress depends on the time required for the glass surface to decrease from the annealing point to the strain point, and the faster the cooling, the greater the difference in shrinkage from the inside, and the greater the compression on the surface after cooling is completed. Stress occurs. Therefore, when strengthening a structure such as a substantially rectangular glass panel having a face portion and a skirt portion, a desired stress distribution can be obtained by controlling the cooling rate of each portion. Regarding a glass panel for a color picture tube,
Usually, a lump of molten glass at a temperature of about 1000 ° C. to 1100 ° C. is supplied into a receiving mold, press-formed by a pressing die, and then a stud pin is sealed to a predetermined inner wall of the skirt. At this stage, the temperature has almost reached the temperature near the annealing point, but by operating the cooling method up to the strain point thereafter, the above-mentioned physical strengthening can be obtained. [0016] Thus, after forming the glass panel portion, for example, the amount of cooling of each portion of the glass panel portion was adjusted to passing through the slow-cooling device, a necessary portion in accordance with the glass material and panel size and shape By cooling at a required cooling strength (speed), a compressive stress layer having an optimum stress value can be formed on the stud pin portion. As described above, in the glass bulb for a cathode ray tube according to the present invention, a compressive stress layer having a predetermined stress value is formed on a glass surface around a stud pin fixed to a skirt portion of a glass panel portion. In order to strengthen the glass by forming the glass panel, it is possible to reliably prevent the glass from being broken when a thermal stress is applied to the periphery of the stud pin due to the difference in the coefficient of thermal expansion in the heat treatment step of the glass panel portion. be able to.

It is a cross-sectional view of a stud pin embedded portion of the glass panel portion according to the BRIEF DESCRIPTION OF THE DRAWINGS [Figure 1] present invention. FIG. 2 is a sectional view of a glass bulb for a cathode ray tube to which the present invention is applied. [Explanation of Signs] 6: Skirt portion 15 of glass panel portion : Stud pin 24: Compressive stress layer 25: Fillet

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01J 29/86 H01J 29/02

Claims (1)

(1) A glass panel comprising a substantially rectangular face portion forming a display screen and a skirt portion extending substantially vertically from a peripheral portion of the face portion. Part, a funnel-shaped funnel part hermetically joined to the glass panel part, and a neck part at the root of the funnel part for storing an electron gun. A metal stud pin is fixed to the skirt part. A glass bulb for a cathode ray tube, wherein a compressive stress layer is formed on a glass member around the stud pin.