Overhead projector optical system - has display lens axis offset from that of condenser lens and inclined to it

摘要

The overhead daylight or bright-chamber projector incorporates illuminating (1, 2) and condenser-lens (3) systems, a display lens (4), and a deflecting mirror (5) with mounting (6). The optical axis of the display lens is offset from the vertical axis of the condenser lens for an amount (delta D) corresponding to an inclination angle (beta) to the vertical. The lens (4) is inclined for an angle (d) to this axis, and for an angle (delta + beta) to the true optical axis of the system. The item-supporting surface (7) is at an angle (alpha) to the horizontal plane of the condenser lens. These angles and that (gamma) of the projection axis to the display wall surface (E') are determined by a formula taking account of the distances of the item and picture (a, b). USE/ADVANTAGE - Absence of distortion and even sharpness and brightness.