Projection television lens assembly

Abstract

A projection television lens system having a device that distorts for telescopically adjusting an A/B assembly, the tubular member that carries the A and B lens elements within a focus mount of a projection television lens system. Additionally, at one end of the lens, there is provided a fixed mounting site, i.e. a mounting site which is fixed in position with respect to the CRT 9 assembly. A device is then provided which connects the fixed mounting site to the tubular member. The thermal and structural characteristics of the device are selected so that the device itself distorts in response to temperature changes and thereby moves the A and B lens elements toward or away from the C element in response to, respectively, increased or decreased ambient temperature. In the most preferred embodiment, the fixed mounting site is on the focus mount at the image side of the lens assembly. The tube, carrying the A/B elements and mounted within the focus mount, is connected to the focus mount by a polymer bar which, at one end, is fixed to the focus mount and, at the other end, is fixed to the A/B assembly. Thereby, when the ambient temperature increases, the bar expands and moves the A/B assembly only axially and not rotationally toward the C element. The material of the bar and its dimensions are selected such that, in response to exposure to increased ambient temperature, the A/B assembly is moved toward the C element by an amount appropriate to maintain focus or substantially compensate for the distortion of the C element.