Patent GB-673820-A (GB)
Title: Mounting arrangement for television pick-up tubes
Inventor: JACKSON DONALD
IPC: H04N5/225
Filed: 1948-08-11
Abstract: 673,820. Cathode-ray tubes. JACKSON, D., and PYE, Ltd. Sept. 24, 1949 [Aug. 11, 1948], No. 21163/48. Class 39 (i). A television pick-up tube has support means secured to it and accurately located with respect to the optical element thereof, such as the photo-cathode or photo-electric mosaic, which has to be located accurately with respect to the camera lens. The television camera comprises a pick-up tube 10, Fig. 1, carried by a cradle 11 which slides along guide-rods 12 mounted in the housing 13 of the camera. The sliding movement adjusts the tube 10 for focusing relatively to the camera lens 14, and is controlled by a lever 15 which is operated through a rod 16 and rocker-arm 17 on a shaft 18 with focusing control handles 19 at each end. The pick-up tube, Fig. 3, of the image iconoscope type, has a glass envelope comprising a chamber 20 connected by a neck 21 to a larger chamber 22, from which extends an arm 23 which contains the electron gun 24 for generating a scanning beam for scanning a mosaic or target electrode 25. A photo-cathode 26 is mounted at one end of the chamber 20. An aluminium pot 30, apertured at 31 to permit an optical image to be focused on the photocathode 26 by the lens 14, is mounted over the exterior of the chamber 20. At its other end the pot has secured to it a flanged ring 32 of magnetic material, which is accurately machined and fits against an accurately machined part of the pot 30. The space between the pot 30 and the tube 10 is filled with cement 33 when the pot 30 and ring 32 have been correctly located in relation to the photo-cathode 26. A second metal ring 34 is mounted over the exterior of the larger part 22 of the pick-up tube by means of cement 35 when the ring is correctly positioned. A coil 36 mounted in an annular housing 37, 38 is used to focus the electron image being transferred from the photo-cathode 26 to the target 25 and is mounted outside the pot 30. The ring 32, being of magnetic material, renders the field of the coil 36 symmetrical around the pick-up tube. The tube fits into a cradle comprising a paddle 55, Fig. 4, attached to two-part cylindrical bearing members 51, 42. A gap 57 accommodates the arm 23 of the tube. The members 42, 51 are spaced apart to a distance corresponding to that between the rings 32, 34 and have internal diameters corresponding to the external diameters of these rings. The member 42 has a flange 46 to engage the ring 32 and locate the pick-up tube longitudinally. The members 51, 42 carry sleeves 62 which slide over the guide-rods 12. Each sleeve is filled with oil, leakage being prevented by end washers. The tube is secured in the cradle by hinged clamps 40, 50 which are tightened by nuts fitted on screws 43, 53. The clamp 40 has a flange 45 to locate against the end wall of the ring 32. The ring 32 carries a U-shaped bracket 70 which supports a cradle 72 and a housing 75 for the deflecting coils 77 which deflect the electron beam in two mutually perpendicular directions. A casing 83 containing the focusing coil 85 is mounted in gimbal bearings so that the focusing coil 85 can be tilted in any direction by means of adjusting screws 87 which extend between the cradle 72 and the casing 83. A spring 88 maintains the casing 83 in contact with the adjusting screws 87. Specification 670,581, [Group XX], is referred to.