GB688121A - Improvements relating to cathode ray tubes - Google Patents

Abstract

688,121. Cathode-ray tubes. BRITISH THOMSON-HOUSTON CO., Ltd., DAVIES, L J., and SCOTT, W. J. Oct. 26, 1950 [Aug. 15, 1949], No. 21227/49. Class 39(i) [Also in Group XXXVI] In a cathode-ray tube the end wall comprises a dome-shaped glass disc of substantially uniform thickness and curvature and a metal ring of such cross-sectional area and having a thermal expansion characteristic so adjusted with respect to that of the glass disc sealed by fusion thereto that when the composite glass-metal end wall has attained an ambient temperature after the sealing process the glass is not subjected to potentially harmful tensile stress, there being sealed to the ring and/or the glass a glass body which forms substantially the whole of the remainder of the envelope, or a glass body which forms a part of the remainder of the envelope and is sealed to a metal body portion forming the major part of the remainder. As shown in Fig. 1 the end wall of a cathode-ray tube consists of a convex glass disc 1 sealed at its rim to a metal ring 2 circular in cross-section, the ring being sealed to a glass body portion 3. The ring may be rectangular in cross-section and formed into a frusto-conical member or annulus Fig. 2 and 3 (not shown) and the disc 1 and body portion 3 of the envelope may mingle where they are fused into the ring, Fig. 4 and 5 (not shown). In Fig. 6 the ring is Z-shaped, the outer and upper flange of the ring retaining the rim of the disc 1 in position, while the downwardly projecting inner flange retains the inner edge of the body portion 3 in position. The glass body portion may be sealed to the glass disc inside the joint which the disc makes with the ring through an intermediate deposit of glass having a lower softening temperature, Fig. 7 (not shown). In Fig. 8 the main body portion 3 is of metal having a thermal expansion characteristic matched to that of the intermediate sealing glass 4. Specifications 462,600, 572,020, [Group XXXVI], 592,038, [Group XXIII], 634,657, 642,668 [both in Group XXXVI], and 6976/48 (as open to public inspection under Sect. 91) are referred to.