Patent GB-672665-A (GB)
Title: Adjustable mountings for use in projection type optical systems
IPC: H04N5/74
Filed: 1947-05-30
Abstract: 672,665. Optical projection apparatus. PHILCO CORPORATION. May 30, 1947 [May 31, 1946], No. 14396/47. Class 97 (i). [Also in Groups XL (a) and XL (b)] An adjustable mounting adapted for supporting a primary image screen in a projection type optical system comprises means providing a pair of individual rotational axes in substantially right-angularly related directions passing through a point lying approximately in said screen and about which axes said screen may be adjusted selectively, whereby said screen can be angularly adjusted about said point as a centre of pivotation. As shown, a cathode-ray tube 13 is provided with focusing coils 27 and deflecting coils 28. The coil housing 27 has an inner cylindrical wall 29 which firmly supports the tube with freedom for axial movement which is adjustable by a spring and nut assembly 30 reacting between coil housing 27 and a collar 31 fixed to the tube. Coil housing 27 is supported by brackets 23 and 24 which are hollow to accommodate the leads to the coils, the brackets being carried by a rectangular frame 25, which is pivotally secured by four arms 26 to a housing 18 which is supported in any convenient manner by a standard 19. Housing 18 supports the mirror 14 and correction plate 15 of a Schmidt system, the mirror being held against an annular seat 34 by crossed resilient members 35 and 36 secured by bayonet slots 37. The correction plate is supported by a plurality of spring clips 38 secured to a flange of the housing 18; adjustment being possible by means of screw members 39 to align the plate and mirror co-axially and thus define an optical axis 20 about which the cathode-ray tube is in turn adjusted. Each of the arms 26 is constructed with a slotted portion 44 through which passes a' securing stud 45 provided with a wing nut 49, and an externally threaded sleeve 46 carrying a knurled nut 48, the sleeve having a rectangular block portion 47 bearing against the outside of housing 18 and sliding between the channel sides 26a of the arms 26. One of the vertical pair of arms 26, and one of the horizontal pair, carries a vernier adjusting device 50 which comprises a screw 54 passing through a flange 53 fixed to an arm 26, and in threaded engagement with a flange 52 of the bracket 47 and carrying a spring 51. Adjustment of the tube is effected by first manipulating the axial adjusting device 30 to bring the tube screen to the point of intersection 22 of the pivotal axes. Adjustment about the Y-axis can then be effected by tightening the knurled nuts 48 of the upper and lower adjusting assemblies and loosening the winged nuts 49, thus preventing any sliding of the upper and lower arms 26, but allowing rotation about the Y-axis by the sliding of the lateral arms with respect to the lateral pivot assemblies; fine control being possible by means of the lateral vernier adjustment. Rotational adjustment about the X-axis is carried out in a similar way by operation of the vertical vernier adjustment. Slight bending of the arms 26 during the adjustment is provided for, without loss of rigidity, by cutouts 56 and 57 in the arm channel-flanges 26a. Specification 672,664 is referred to.