Patent GB-451517-A (GB)
Abstract: 451,517. Clocks. ERICSSON TELEPHONES, Ltd., 67, Kingsway, London, and ENGBLOM, J. F. T., Villa Tomoana, Elm Avenue, and WILMAN, C. W., 7, Grange Avenue, both in Beeston, Nottingham. March 5, 1935, No. 6911. [Class 139] [See also Group XIX] An indicator for displaying the time of the day comprises a series of endless flexible bands bearing characters, the bands having perforations cooperating with brushes whereby a transfer may be effected electrically from a band displaying a digit of one order to a band displaying a digit of higher order. Four indicating bands MU, MT, HU, HT for showing units and tens of minutes and hours respectively are provided, each band being arranged and operated as described in Specification 437,914. In the condition shown, the apparatus displays the time 10-00. A relay A is operated at the end of every minute and closes contacts a1 for a relay B which completes at b3 the circuit of a motor M driving an interrupter I adapted when operating to supply earth potential alternately to two circuits described below. Relay B is held via contacts b1, b2 and brushes p, q which pass through perforations in the band to engage a conducting bar h. Earth potential is supplied to the bar h from contacts a1 and is extended to a brush t at this time engaging the bar, a magnet E thus being operated to close contacts e1, e2 in the circuits of magnets C, D. These magnets are alternately energized on account of the earth connections made by the interrupter I and the band MU is advanced. As soon as the movement commences, the bar h, which is arranged between the driving sprockets, moves from beneath the brushes p, q, t. Relay B thus releases and brush t is lowered on to an earthed disc g to maintain the circuit to the magnet E. When the band has moved through one division, the bar h comes again into the position shown and lifts the contact t from the disc g to break the circuit of the magnet E and stop the band. The device now indicates 10-01. At 10-09, a brush r contacts with the bar h through a perforation in the " 9 " position of the band. When relay A releases after the next impulse and bar h is connected to earth via a1, b1, earth potential is extended from h through brush r, brushes pa, qa and bar ha of the indicator MT, to the lower (opposed) winding of magnet E, which is thus neutralized. Earth is also supplied from the bar ha through brush ta to a magnet EA which closes contacts ea1, ea2 in the circuits of actuating magnets CA, DA, the tens of minutes bands MT thus being operated. When the bar ha moves it breaks the connection between the brushes pa qa. The lower winding of E is thus de-energized and E operates to advance the units of minutes band MU. The bands come to rest to indicate 10-10. At the clock impulse following 10-59, since a perforation in the band MT is beneath the brush ra, earth potential is extended also to bar hb of indicator HU. Magnets E and EA are both held by current in their lower windings until band HU advances, whereupon bands MT and MU advance in turn to show 11-00. At the impulse following 12-59, band HT is advanced from " 1 " to " blank " and the other bands are then moved to show 1-00. Specification 432,447 also is referred to.