Patent GB-730777-A (GB)
Title: Improvements in date indicators
IPC: G04B19/253
Filed: 1952-05-23
Abstract: 730,777. Date indicators. HARRISON, T. H. May 21, 1953 [May 23, 1952], No. 13186/52. Class 106 (4). A clock-actuated date indicator of the kind described in Specification 543,270 has a date and a month ring each formed with a single track thereon, each track being adapted both to cooperate with a rotatable feed member to effect feed of the ring and to cooperate with a control plate to effect the requisite control of the feed imparted at least to the other of the date and month rings. As shown, the indicator comprises a clock dial E, Fig. 2, formed with four concentric grooves locating a date ring A, month ring B, year ring C and day ring D, all appropriately marked for displaying the date through an aperture cut in the dial E. A control plate 26, Figs. 2 and 4, behind the rings, has apertures, through which protrude teeth formed in tracks extending back from rings A, B and C, and also tongues whereby certain rings control the feed of other rings. A rotatable member 25, Figs. 2 and 5, is driven one revolution a day by the clock, anticlockwise as seen in Fig. 5, and is provided with four resilient actuating tongues: tongue 31 with depth control portion 33 and day ring feed tooth 32, tongue 34 with depth control portions 37 and 38 and two date ring feed teeth 35, 'wide and shallow and 36 narrow and deep, tongue 24 with depth control portions 40, 41 and a tooth 39 for a month ring and year ring feed. The date ring A, Fig. 3, has 31 teeth, similar except for a deep tooth 2 and an extra side tooth 1. The month ring B has 12 teeth of forms shown in Fig. 9 appropriate to the length of month and disposed in the order of the months, one of the narrow teeth 10A, Fig. 3, is deeper than the rest. The year ring C has three sets of four teeth, three deep and one shallow in each set corresponding to leap year cycles. The day ring D has seven similar teeth. The control plate 26 has seven tongues: tongue 11 presses the date ring A against the dial E, tongues 12, 13 co-operate with the month ring B, and tongue 14 with the year ring C, to control the feed of the date ring A by the tongue 34, the tooth 36 being held out of engagement with the side tooth 1 by ribs 20 on the tongues 12, 13, 14 unless these tongues are allowed to drop by the appropriate ring, tongue 17 co-operates with the date ring A having a side projection for engaging the deep tooth 2, tongue 18 retains month and year rings B, C in position except during a change-over and tongue 19 similarly retains the day ring D. In operation it is usually convenient for all the changes of indication to take place around mid-night. Day change is effected by the tooth 32 of the tongue 31 engaging a tooth of the day ring D when the depth control portion 33 drops into the gap 15 of the control plate 26 for a seventh of a revolution of the member 25. As described, date change is completed at midnight when the depth control portion 38 of tongue 34 rides out of the gap 15 into which it dropped a seventh of a revolution of the member 25 earlier, and, unless it is the last day of a month of less than 31 days, the tongue 12 of the control plate 26 holds the tooth 35 clear of the date ring A until a thirty-first of a revolution before mid-night whereupon the date-is advanced. In a 30-day month the tongue 12, Fig. 8, drops throughout into the wider tooth of the month ring so that it no longer controls the tooth 36 but the tongue 13 holds the tooth 36 clear of the path of the side-tooth 1 of the date ring A until two thirty-firsts of a revolution before mid-night whereupon on the 30th day the teeth engage and the date ring A is advanced to the first. In a 28-day February the tongues 12, 13, Fig. 9, drop throughout into the widest tooth of the month ring and the tongue 14, Fig. 11, drops into one of the wide teeth of the year ring so that the tongues 12, 13, 14 no longer control the tooth 36 and when four thirty-firsts of a revolution before midnight on the twenty-eighth the teeth 1 and 36 engage, the date ring is advanced to the first. In a 29-day February the tongue 14 remains in control and the date is advanced to the first at the end of the twenty-ninth day when the teeth 1 and 36 engage three thirty-firsts of a revolution before midnight. When the first of any month is displayed the tongue 17 of the control plate 26 drops into the deep tooth 2 of the date ring A and at midnight the depth control portion 41 of the tongue 24 allows tooth 39 to engage the month ring B until a twelfth of a revolution after midnight, the portions 41, 40 ride out of the gap 16 and the month change is completed. During the month change from December to January the deep tooth 10A of the month ring B allows the tooth 39 to engage the year ring to effect the year change. A method of adjusting the calendar manually is described.