Patent GB-869133-A (GB)
Title: Improvements in or relating to means for effecting registration in colour televisionprojection systems
Inventor: RIDGEWAY DENIS VICTOR
IPC: H04N5/74
Filed: 1956-08-30
Abstract: 869,133. Cathode-ray tube mountings. PYE Ltd. Aug. 30, 1957 [Aug. 30, 1956], No. 26549/56. Class 40(7) [Also in Groups XX, XL(a) and XL(b)] In a colour television projection system in which a plurality of component colour images are combined in register on a viewing screen to form a composite colour picture, precise registration is effected by purely mechanical means which are provided for adjusting the size, focus and position of each component image on the viewing screen. Each component colour image is produced by a projection type cathode-ray tube (Figs. 1 and 2) which, as shown, is supported by two spider supports 25, 54 carried by a pair of rails 28 pivotally mounted at 5 in a pair of members 2 and supported, at the other end, by a pair of slotted members 3 which allow the assembly to be clamped with the tube at a desired inclination to the horizontal (Fig. 2). The members 2 and 3 are attached to a base member 4 pivotally mounted at 11 on a further base member 10 to which it may be clamped, in a desired position in the horizontal plane (Fig. 2), determined by the limits of a slot 13, by means of a clamping arrangement 12, 14. The base member 10 is slidable along a recess 6 in an additional base member 9 being secured thereto by a clamping arrangement 74 co-operating with a slot 73 in base member 10. Base member 9 carries a vertical mounting plate 16 provided with slots to allow movement of the base members 4 and 10 and the rails 28 and carrying, at a central aperture, the corrector plate 41 through which the neck of the tube projects. The sides of the plate 16 carry pivot pins 65 which engage holes 64 in two support members 63 secured to another base member 58 thus allowing the position of base 9 and the complete optical assembly, including the spherical mirror 20, to be adjusted in the vertical plane by an amount determined by a slot 60 in a bracket 59 attached to base 58 the assembly being clamped in the desired position by means of clamping nuts 62 and 66. To allow the position of the assembly to be adjusted in the horizontal plane the base 58 is pivoted at 67 to a main base member 69 clamping means 70, 71 associated with an arcuate aperture in base 58 being provided for securing the latter in the desired position. Summarizing the adjustments so far described it is seen that; tube 1 may be pivoted about point 5 with respect to base 4; base 4 may be pivoted about point 11 with respect to base 10; base 10 may be slidably moved with respect to base 9; base 9 may be pivoted about points 64 with respect to base 58; base 58 may be pivoted about point 67 with respect to the main base 69. These adjustments allow correct optical focusing and positioning of the images produced by a plurality of assemblies of the kind described when such images are themselves correctly positioned and focused on each of the tubes. To allow of the latter adjustments the focusing coil 37 of each tube is carried by the combination of a flexible spider 39 and a rigid spider 38 both of which are slidably mounted on the rails 28 to which they may be clamped, in the position of correct focus, by clamping means 33. For adjusting the orientation and size of the images the deflection coils 44 are loosely mounted around the tube neck in a collar 45 carried by a spider 46 also slidably mounted on the rails 28 and adapted to be clamped by means of clamping nuts 46a in the position giving the desired size of image the coils additionally being rotatable around the tube neck, controlled by handle 51, to vary the orientation of the image. The focusing coils and the deflection coils (line and frame) of all the tubes are connected, respectively, in series so that in setting up the equipment, absolute electrical adjustment may be effected simultaneously for each respective set of coils, adjustment of the relative conditions then being effected by varyin the positions of the coils. Details of the complete procedure for aligning the images produced by a plurality of assemblies such as described on a viewing screen are given.