Patent GB-432447-A (GB)
Title: Improvements in or relating to indicators for displaying variable information
IPC: G09F11/26
Filed: 1934-03-13
Abstract: 432,447. Changing signs. ERICSSON TELEPHONES, Ltd., 67, Kingsway, London, WILMAN, C. W., and TRAPP, C. C., Ericsson Telephone Works, Beeston, Nottingham. March 13, 1934, No. 7903. [Class 3 (i)] An indicator for displaying variable information comprises an endless band 25 passing round a plurality of rollers, one of which is progressively driven by the alternate energization of two electromagnets 11, 12. The band-driving roller comprises a sleeve provided with two armature end discs 19 having each a plurality of projections 19<a>, 19<b>, all these parts being of magnetic material, and the magnets 11, 12 are so disposed that each on being energized attracts a projection and turns the roller through an angle equal to one half the angle between two adjacent projections. The rim of each projection is shaped spirally to lessen gradually the air-gap between projection and magnet, and so maintain constant torque, and friction washers are assembled between the frame and the discs 19. The rollers are all mounted on frame stay-bolts 4, 5, 6, 7, 8, and other bolts 3, 9, 10 serve respectively as a lifting handle and as cores for the electromagnets. The cores 9, 10 are mounted eccentrically in the frame, which is of non-magnetic material. The sleeves forming the main part of the rollers are mounted on the bolts by roller bearings. The band 25 may be of book-binder's cloth having a selvage, or be cut with neither warp nor weft parallel to the edge, its ends are laced together by a thread of celluloid &c., and its tension is made adjustable by mounting the bolts 4 and 5 eccentrically. The edges of the band have equally spaced perforations to engage teeth 21, 22 on the driving roller, and two of these teeth are more closely spaced than the rest to allow of the band passing over a cross-rod 20 located between these teeth and insulatedly mounted on the discs 19. The rod 20 acts as contact for a series of brushes f fixed in an insulating block 27 and having their ends resting, when out of action, in a notched support 28. The band 25 is provided with combinations of orifices between each display section, and the brushes f make contact with the bar 20 through these orifices and stop the movement of the band when a selected section is at the display window. No orifices are provided between the sections which would bring the band joint into view. The brushes f are connected to a strip which can be swung out of position to allow the frame 1 to be inserted in a rack in close proximity to a plurality of similar frames to form a composite display. In a modification, a registering detent for the discs 19 is provided, being actuated by an electromagnet which simultaneously with detaining the discs breaks the pulsing circuit for the magnets 11 and 12. This gives a continuous motion to the band, and the impulses imparted to the magnets 11 and 12 may overlap to assist this effect. The selecting switch for determining which section of the band shall stop at the display window comprises a knob 43, Fig. 8, on a spindle 41, carrying an indicator disc 44 showing through an opening in a cover plate 51. The spindle 41 passes through an insulating block 56 and has fixed to the lower end two cams 45, 46 insulated from one another. The cams contact in succession with springs F on the block 56, bringing successive springs into the impulse circuit, and the springs F are electrically connected to the brushes f, each to each. An interrupter connects the magnets 11, 12 in succession through a relay with the springs F, and the band is moved intermittently or continuously to the position corresponding to the one revealed on the disc 44. The indicator may generate its own impulses, and the code holes in the band may be replaced by external means, such as a step-by-step electromagnetic rotary switch, for counting the actual number of impulses supplied to the magnets. The brushes f may be replaced by contacts operated from the driving spindle or from sprockets driven by the band. More than one armature spindle 8 may be employed on a single indicator, and more than one armature may be operated by the same pair of magnets. Further, a plurality of bands building up a composite display may be geared together. The magnets 11, 12 may form part of a polarized system for control over a two-wire circuit by reversal of current direction at each impulse.