Patent GB-979420-A (GB)
Title: Electric perpetual calendar
IPC: G04C17/00
Filed: 1961-11-02
Abstract: 979,420. Date indicators. G. E. DUNNING. March 13,1962 [Nov. 2, 1961], No. 39208/61. Heading G3T. An automatic calendar comprises a mechanism for the display of day numerals and month names, which is driven by drive means actuated by a single solenoid, the solenoid being operable by switching means controlled by a clock and by further switching means, whereby to operate either singly or repeatedly and effect a predetermined sequence of change of the display. The electrically operated perpetual calendar, displaying from separate apertures the day numerals and month names, is in circuit with an electric clock 1 which daily on midnight by a cam and follower 4, 5 closes a micro master switch 6 to energize the solenoid 7 and normally to advance by one day the pivoted flap type day numeral drum 21 through a ratchet wheel 13 of thirty-six teeth driven by a pawl 12 carried by a spring-biased lever 10 connected to the solenoid armature 8. The lever 10 carries two yoked tappets 18 operating a micro limit switch 19 in circuit with a relay 20 which operates a pair of change-over contacts a1, a2 whereby the advancement of the ratchet wheel is repeated successively at the change of the month. The drum 21 carries rotatably therewith a two-pronged contact 26 of which the prongs bear respectively on an inner continuous slip ring 31 and an outer discontinuous slip ring 32 corresponding to twenty eight teeth of the ratchet wheel, the gap being occupied by three contacts 33 corresponding to the twenty-ninth, thirtieth,and thirty-first of the month, followed by a non-contact space corresponding to the remaining five teeth of the ratchet wheel and to blanks on the numeral flaps 24. Rotatable with the contact 26 is a finger eccentrically disposed in relation to a month name drum 36 so as to engage once each revolution one of twelve projections 42 on the drum to advance it one step. The name drum is carried by a shaft 38 indexed by ball detents 39. This shaft 38 carries two wafer type contacts each engaging a ring of twelve fixed contacts 37. As shown in Fig. 9, one ring of twelve contacts has all its contact positions joined together excepting for one position which represents Feb. The second ring of twelve contacts has all the contact positions joined excepting for positions which represent Feb., Apr., June, Sept., and Nov. A year switch 43 having three contacts of which two are joined together, is manually changed on leap year so that whilst in normal years the joined contacts are in the position shown, on leap years the centre and right hand contacts are joined. With the connections shown, it will be seen that when the appropriate day at the end of each month is reached, the two-pronged contact 26 will reach a position providing an open circuit between the continuous slip ring 31 and the discontinuous slip ring 32, whereby the relay 20 will be de-energized by opening of the limit switch 19 and re-energized on closing of this switch so as to cause the stepping-on of the ratchet wheel to be repeated until the contact 26 again contacts both slip rings, thus effecting the monthly change-over. A share calendar may be operated by plugging in to a socket 44.