Glass bulb for cathode ray tube

#The present invention relates to a glass bulb for cathode ray tube used in a television and the like.

#As shown in FIG. 3, a glass bulb 1 for cathode ray tube generally comprises a glass panel 10 serving as a front surface portion, a funnel 20 serving as a back structural member and a neck 30 for mounting an electron gun therein. The glass panel 10 includes a face portion 11 of approximately rectangular shape having an effective screen for displaying an image, and a skirt portion 13 continued from the periphery of the face portion 11 via a blend R portion 12 and having a seal edge surface portion 14 for sealing with the funnel 20.

#The funnel 20 includes a top portion 22 extending nearly vertically in the tube axis direction from a seal edge surface portion 21 for sealing with the glass panel, a yoke portion 24 outside of which a deflection yoke is to be attached, and an intermediate body portion 23 connecting the top portion and the yoke portion. A reference line 25 existing in the yoke portion is a hypothetical line used for indicating a reference position of the funnel. In the case of a color cathode ray tube, the glass panel 10 is sealed between the seal edge surface portion 14 of the skirt portion 13 and the seal edge surface portion 21 of the funnel 20 via frit glass and the like. In this context, θ designates a deflection angle in the yoke portion of the funnel 20, and is defined as an angle of divergence of an effective screen diameter D along the diagonal axis of the rectangular face portion 11 viewed from a hypothetical reference point on the reference line 25.

#FIG. 1 is an explanatory view in short axial section of a glass bulb for cathode ray tube according to the present invention;

#FIG. 2 is an explanatory view of distribution of vacuum stress generated in the glass bulb for cathode ray tube;

#FIG. 3 is an explanatory view of a glass bulb for cathode ray tube;

#In the following, a glass bulb for cathode ray tube according to the present invention will be described with reference to working examples. FIG. 1 is an explanatory view in short axial section of a glass bulb for cathode ray tube according to the present invention. The components as same as those described above will be denoted by the same reference numerals and explanations thereof will be omitted.

#In the drawing, the reference numeral “h” denotes a distance in the tube axis direction along the short axis of the glass panel 10 from a contact between the end portion of the effective screen of the inner surface of the face portion 11 and the blend R portion 12 to the seal edge surface portion 14, of the skirt portion 13 which is defined as the length of the skirt portion. The reference numeral “H” denotes a distance along the tube axis direction from the seal edge surface portion 21 of the funnel 20 to the reference line 25.

#Panels and funnels used for glass bulbs for cathode ray tube according to the present invention, and panels and funnels used for glass bulbs of comparative examples were individually manufactured and the weights of these panels and funnels were measured. After sealing the funnel and a neck to the corresponding glass panel to make a glass bulb, the air was exhausted from the interior thereof, and then a vacuum tensile stress value of the seal edge portion of each glass bulb was measured by means of a strain gauge.