Patent GB-748254-A (GB)
Abstract: 748,254. Calendars. GILSON, R. J. Nov. 15, 1954 [June 11, 1954], No. 17248/54. Class 106 (4). A perpetual calendar comprises a reference member 20, such as a casing having windows 25 ... 27, pointers or the like to expose or indicate appropriate portions of three movable scales 30, 35, 43 marked with year numbers, month names and day dates respectively, the markings on the scales being so arranged, and movement of the year number scale and the month name scale so transmitted to the day date scale that movement of the year number scale and month name scale to positions in which a selected month and year are exposed or indicated brings numbers on the day date scale representing all the days of that month into correct register with day name headings. The movement of either year-number scale or month name scale may be transmitted to the day date scale without movement of the other of the said scales. Additional mechanism, acting in response to movement of the month name and year number scales modifies the movements of the scales to compensate for the extra day in leap years. The day date scale 30 is marked with five overlapping spiral rows of numbers so that any seven radial columns contain all the numbers from 1 to 31 inclusive. Dial 35 contains the month names and dial 43 the year numbers. A pinion 59, fast with spindle 28 which carries the day date scale 30, meshes with a gear 56 mounted on a pin 57 fixed in the casing. A lever 53 pivoted eccentrically at 58 on the gear 56 has at its ends cam followers, one of which, 54, engages a cam 38 fixedly mounted on the spindle 34 which carries the month name scale 35 and the other, 55, engages a cam 45 fixedly mounted on the spindle 42 which carries the year number scale 43. Rotation of either the month name scale or the year number scale rocks the lever 53 about its point of engagement with the cam thus turning the gear 56 which turns the day date scale to its correct position corresponding to the year and month shown at the windows 27 and 26 respectively. Further cams 39 and 46 fixedly mounted on the spindles 34 and 42 respectively co-operate with a lever 61 which is pivotally connected to a rocking arm 64 pivoted at 65 in the casing, and carrying the bearing 32 for the spindle 34, the bearing 32 being movable in a slot 33 in the back of the casing. A spring 68 urges the arm 64 against the fixed stop 69. The cam 46 has lobes 47 so located that when a leap year number is exposed one of them engages the cam follower 67. The cam 39 has a notch 40 into which the cam follower 66 drops when either the January or February month name is exposed. When a leap year and a month name other than Jan. or Feb. is exposed the spindle 34 is displaced, transmitting additional movement to the day date scale. Knobs are mounted on the spindles 34 and 42 for month and year scale adjustment. Spring- loaded pawls 51 and 52 co-operate with discs 41 and 48 respectively to locate the month names and year numbers in the windows 26 and 27. In another embodiment the month name and year number scales rotate each with a spur wheel, each spur wheel meshing with one of two coaxial spur wheels which, meshing with planetary bevel pinions set the day date scale. The leap year adjustment is provided by marking Jan. and Feb. on a sub dial movable relative to the month name scale, displaced by a lever mechanism each leap year. In another embodiment the movable scales are carried by endless bands connected by a suitable mechanism, leap year adjustment being provided by movement of a bi-coloured transparent shutter, the month names Jan. and Feb. being marked twice, in two different colours on the month name band. In both these embodiments the correct selection of the day date scale is achieved by the positioning of the month names and year numbers on their respective scales. In a further embodiment four drums carry respectively the day names, day dates, month names and year numbers.