GB1305699A - - Google Patents

Abstract

1305699 Colour television tubes RCA CORPORATION 19 April 1971 [6 April 1970] 26326/71 Heading H1D [Also in Division B3] In a colour television tube having a shadow mask supported by springs from studs on the envelope, the aperture in the spring through which the stud passes is defined by curved surfaces having smaller curvature than the co-operating surface of the stud. In Fig. 9 the aperture is defined by three circular arcs 27 centred respectively at points a, b and c. The radius of the arcs should be 4-10% greater than the radius of the inscribed circle 17<SP>1</SP> which is the desired contact position of a conical stud; the actual contact position may be as shown at 17 and the contact area is still great enough to prevent the gouging which may occur in known arrangements. The edges of the aperture may be curved in planes containing the axis A. In a specific example, Figs. 11 and 12 (not shown), the radius of the circle 17<SP>1</SP> is 0À110 inch, the radius of the arcs 27 is 0À115 inch and their centres are 0À005 inch from the axis A, and the edges are curved to a radius of 0À125 inch; the position of the centre of curvature of the edges depends on the taper of the studs which may be between 7 and 12 degrees. As an alternative the tip of the stud may have the curved surface illustrated and co-operate with a circular aperture.