GB2371882A

GB2371882A - Perpetual monthly calendar mechanism

Info

Publication number: GB2371882A
Application number: GB0102849A
Authority: GB
Inventors: Richard George Hoptroff
Original assignee: ALIEN DOG STAR INVEST Ltd
Current assignee: ALIEN DOG STAR INVEST Ltd
Priority date: 2001-02-06
Filing date: 2001-02-06
Publication date: 2002-08-07
Anticipated expiration: 2021-02-06
Also published as: GB0102849D0; GB2371882B

Abstract

A perpetual monthly calendar mechanism comprises at least two wheels having 35 driving positions and linked to discs showing the days of the week 1 (five times over) and the dates of the month 2 plus four spaces. A cover disc 3 with notches (see also Fig 4) covers those of the end dates 29-31 not required for the current month. The mechanism for changing the date back to one at the end of the month can be based on a modification of either Brocot or Audemar's mechanisms. Preferably, the dates are arranged spirally on the date disc 2 (Fig 3 or Fig 5). A pointer 5 can be provided to indicate the current date and is moved by a notched wheel. An alternative mechanism (Fig 6) has the discs connected to wheels so as to move five positions for every one wheel movement.

Description

ENTIRE MONTH PERPETUAL CALENDAR INDICATOR This invention relates to a mechanical device that provides an indication of the day of the week for each day in a month. It may be driven via a modification of the majority Perpetual Calendar Mechanisms (PCMs) known to the art.

A perpetual calendar mechanism indicates the current day, date and month. The 7position day indicator (Monday, Tuesday, etc) indicator is advanced by one position at midnight. The 31-position date indicator (1,2,..., 31) indicator is also advanced by one position at midnight. The 12-position month indicator is advanced one

position each time the date indicator returns to the" 1" position. To provide for months consisting of fewer than 31 days, several mechanisms are known to the art for advancing the date indicator to the"31"position immediately prior to midnight on the last day of the month as appropriate.

Most known PCMs derive either from Brocot's perpetual calendar or Audemar's perpetual calendar. These mechanisms are detailed in Appendices 1 and 2 respectively. (These appendices are reprints from F J Britten's Watch & Clock Makers'Handbook, published 1907. Mr Britten died in 1915 and hence these appendices are copyright-free and the mechanisms are patent-free.) Brocot's calendar works by advancing the date wheel a fixed number of positions on the 31-position date wheel at the appropriate moment. The appropriate moment is determined by a notched wheel ("v"in Appendix 1) that turns once every four years.

The notches prescribe that the date wheel must be advanced by the following number of days at the following times:

Month At the end of this... advance the day... wheel this many positions January 31 0 February, non-28 3 leap year February, leap 29 2 year March 31 0 April 30 1 May 31 0 June 30 July 31 0 August 31 0 September 30 1 October 31 0 November 30 1 December 31 0 Audemar's calendar works by resetting the date wheel to the" 1 " position at the appropriate moment. The appropriate moment is determined by a notched wheel ("E" in Appendix 2) that turns once every four years. The notches prescribe that the date wheel must be reset as follows:

Month Reset to date wheel to one and advance the month wheel at the end of this date January 31 February, non-28 leap year February, leap 29 year March 31 April 30 May 31 June 30 July 31 August 31 September 30 October 31 November 30 December 31 The present invention modifies either Brocot's or Audemar's mechanisms (or their derivates) in order to obtain a display of the entire month's calendar.

The present invention uses two wheels with 35 positions. One wheel represents the day of the week (five times over). It rotates by one position every day. The other represents the dates 1... 31 (plus 4 redundant positions). This also advances one position per day, plus, through an adaptation of the notched wheel in either Brocot's or Audemar's mechanism, an appropriate number of positions at the end of the month.

The wheels are attached to display discs that display the days of the month and the dates of the month, such that the day and the date wheels align to display a monthlong calendar.

A mask may be used to hide the numbers 29,30, and/or 31 on the date disc when it is appropriate to do so. An adaptation of the notched wheel in either Brocot's or Audemar's mechanism may be used to position the mask.

The current day in the month will always lie along the same radial on the discs. The current date may be indicated by a pointer that tracks its position along the radial.

A preferred embodiment (Figure 1) uses three concentric wheels linked directly to, (or indeed are, ) the concentric display discs. The first disc, 1, displays the day of week five times over. (This is shown in detail in Figure 2. ) The second disc, 2, which lies in front of the first, displays the date as a spiral of numbers. (This is shown in detail in Figure 3). And a third'disc, 3, lies in front of both discs I and 2 and masks any numbers 29,30 and 31 which are not appropriate to the current month. It also displays the dates for the start of the following month. (This is shown in detail in Figure 4. ) A mask, 4, hides all but 720 ouf the disc so that the remaining sector depicts a month calendar. A pointer, 5, arcs around an off-center pivot, 6, in order to indicate the current date.

The wheels linked to discs 1,2 and 3 of the embodiment are advanced anticlockwise by one 35th of an entire rotation at each midnight. The wheels linked to discs 2 and 3 are also advanced at the end of each month using an adaptation of Brocot's mechanism. The adaptation is as follows:

Month At the end... advance disc... advance disc of this 2 by this many 3 by this many day... positions positions January, non-leap 31 4 4 year January, leap year 31 4 5 February, non-28 0 (or7) 3 leap year February, leap 29 6 3 year March 31 4 6 April 30 5 1 May 31 4 6 June 30 5 1 July 31 4 0 August 31 4 6 September 30 5 1 October 31 4 6 November 30 5 1 December 31 4 0 The pointer is advanced to track the position of the current date down the spiral. This may be driven by a cam connected to the wheel linked to disc 2 or disc 3.

An alternative embodiment (the"first alternative embodiment") is used when the device must be driven by an adaptation of Audemar's mechanism. Two concentric wheels linked directly to, (or indeed are, ) the concentric display discs. The first disc, 1, displays the day of week five times over (as in Figure 2. ) The second disc, 7, which lies in front of the first, displays the date as a spiral of numbers. (This is shown in detail in Figure 5). The numbers 29,30, and 31 are arranged such that they may be readily masked by any mechanism that moves to mask entire arcs of the second disc so that the appropriate numbers are masked in all of their possible positions.

The wheels linked to discs 1 and 2 of the embodiment are advanced anticlockwise by one 35th of an entire rotation at each midnight. The wheel linked to disc 2 is advanced, and the mask positioned, at the end of each month using an adaptation of Audemar's mechanism. The adaptation is as follows:

Month Reset to date disc... and mask the 2 to"I"at the end following of this date... numbers January, non leap-31 29,30, 31 year January, leap year 31 30, 31 February, non-28 (none) leap year February, leap 29 (none) year March 31 31 April 30 (none) May 31 31 June 30 (none) July 31 (none) August 31 31 September 30 (none) October 31 31 November 30 (none) December 31 (none) Another alternative embodiment (the"second alternative embodiment") is an adaptation of either of the first two embodiments. In this adaptation, the discs are linked to the wheels such that for each turn of a wheel the discs turn five times. The necessary discs are shown in figure 6. The day disc, 8, has seven sectors, one for each day. The date disc, 9, displays the dates in a spiral of one rotation every seven days.

As before, a mask, 10, hides the dates that are not relevant to the current mechanism.

(The two alternative mechanisms for this mask are detailed in the first two embodiments. ) A pointer, 11, may be used to indicate the current date. This may be driven by a cam connected to the wheel linked to either disc 9 or mask 10. APPENDIX 1: BROCOT'S PERPETUAL CALENDAR MECHANISM Perpetual Calendar Work. -Figs. 2, 3, 4 and 5 illustrate m. Brocot's arrangement of calendar, lunation, equation work.

The various parts are planted on a circular plate, of which the inner side containing the pieces for indicating the days of the week and the days of the month, is shown in Fig. 3. Fig. 5 shows the outer side of the plate, which is devoted to the mechanism for producing the phases of the moon and the equation of time. To this side of the plate the dial (Fig. 4) is attached.

The calendar is actuated by means of a pin e fixed to a wht-el of the movement which turns once in 24 hours. Two clicks G and H are pivoted to the lever M w, G is kept in contact with a ratchet wheel of 31 teeth, and II with a ratchet wheel of 7 teeth.

As a part of these clicks and wheels is concealed in Fig. 3, they are shown separately in Fig. 2.

When the lever M is moved by the pin e, the clicks s. and H slip under the teeth, their beaks pass on to the following tooth, and the lever then, not leaning on the pin e, falls quickly by its own weight, and makes each click leap a tooth of the respective wheels of 7 and 31 teeth. The arbors of these wheels pass through the dial (Fig. 4), and have each an index which, at every leap of its own wheel, indicates on its special dial the day of the week and the day of the month. A roll or jumper, kept in position by a sufficient spring, keeps each wheel in its place during the interval of time which separates two consecu- tive leaps. BROCOT'S PERPETUAL CALENDAR.

To secure the proper registration of the months of 30 days, for February of 28 during three years, and of 29 in leap year, M. Brocot makes the following provision. The arbor A of the month wheel goes through the circular plate, and on the other side is fixed (see Fig. 5) a pinion of TO. This pinion, by means of an intermediate wheel (D), works another wheel (centred at e) of 120 teeth, and consequently turning once in a year. The arbor of this last wheel bears an index indicating the name of the month. The arbor c goes through the plate, and at the other end (see Fig. 3) is fixed a little wheel gearing with a wheel having four times as many teeth, and which is centred at F.

This wheel is partly concealed in Fig. 3 by a disc (v), which is fixed to it, and with the wheel makes a turn in four years. On this disc are made 20 notches, of which the 16 shallowest corre BROCOT'S PERPETUAL CALENDAR.

spend to the months of 30 days, a deeper notch corresponds to the month of February of leap year, and the last three deepest to the month of February of common years in each quaternary

period. The uncut portions of the disc correspond to the months of 31 days in the same period. The wheel of 31 has a pin (i) placed before the tooth which corresponds to the 28th of the month. On the lever M m is pivoted freely a bell-crank lever (N n), having at the extremity of the arm n a pin (o) which leans its own weight upon the contour of the disc v, or upon the bottom of one of the notches, according to the position of the month, and the arm N is therefore higher or lower according to the position of the pin o upon the disc.

It will be easy to sec that when the pin o rests on the contour of the disc the arm" of the bell-crank lever is as high as possible, as it is dotted in the figure, and then the 31 teeth of the month wheel will each leap successively one division by the action of the c ! ick c. ti ! ! thf-it day. But whr-n the pin 'is in one oi the click r,, till tlif--pin ('s is in the shallow notches corresponding tu itte ntonths of 30 days. the arm N of the bell-crank lever will take a ! u\ver position, and the inclination that it will havebytheforward movement of the lever M nu will bring on the 30th the pin/in contact with the bottom of the notch, just a the lever has accomplished two thirds of its movement, so the last third will be employed to make the wheel 31 advance one tooth, and the hand of the dial

by consequence marks 3Ist, the quick return of the lever putting this hand to the ist. If we suppose the pin o in the shallowest of the four deep notches, that one for February of leap year,

the end of the arm x will take a position lower still, and on the 29th the pin i will be met by the bottom of the notch, just as the lever has made one-third of its course, so the other two-thirds will serve to make two teeth of the whcd of 31 jump. Then the hand of the dial will indicate 3I, the ordinary quick returns of the detent putting it to the ist. Lastly if, as it is represented in the figure, the pin o is in one of the three deepest notches, corresponding to the months of February in ordinary years, the pin will be in the bottom of the notch on the 28th just at the moment the lever begins its movement, and three teeth will pass before the return of the lever makes the hand leap from the ist to the ist.

The pin o easily gets out of the shallow notches, which, as will be seen, are sloped away to facilitate it doing so. To help it ut of the deeper notches there is a weighted finger (i) on the arbor of the annual wheel. This finger having an angular movement much larger than the one of the disc G, puts the pin o out of the notch before the notch has sensibly changed its position.

Phases of the Moon. The phases of the moon are obtained by a pinion of 10 on the arbor B, which gears with a wheel of 84 teeth, fixed on another of 75, which last gears with a wheel of 113, making one revolution in three lunations. By this means there is an error only of'0008 day per lunation. On the wheel of 113 is fixed a plate (z), on which are three discs coloured blue having between them a distance equal to their diameter, as shown in Fig. 4 ; these, discs slipping under a circular aperture made in the dial, produce the successive appearance of the phases of the moon.

Equation 01 Time. -On the arbor of the annual wheel is fixed a brass cam or"kidney piece" (y), on the contour of which leans the pin s, fixed to a circular rack (R). This rack gears with the central wheel (K), which carries the hand for the equation. That hand faces XII. the igth April, ith June, ist September, 25th December. At those days the pin s is in the position of the four dots marked on the kidney piece. The shape of the kidney piece must be such as will lead the hand to indicate the difference between solar and mean time, as given in the table under the head of time.

Manner of Adjusting the Calendar. -Firstly, the return of the lever M m must be made at the moment of midnight. To adjust the hand of the days of the week, look at an almanac

and see what day before the actual date there was a full or new moon. If it was new moon on Thursday it would be necessary, by means of a small button fixed at the back, on the axis of the hand of the week, to make as many returns as requisite to obtain a new moon, this hand pointing to a Thursday. and after to bring back the hand to the actual date, passing the number of divisions corresponding to the days elapsed since the new moon. To adjust the hand of the month, see if the pin o is in the proper notch. If for the leap year, it is in the month of February in the shallowest of the four deep notches (o) ; if for the same month of the first year after leap year, then the pin should be, of course, in the notch i, and so on. APPENDIX 2: AUDEMARS'S PERPETUAL CALENDAR MECHANISM Perpetual Calendar Watch. -The wheel II (Fig. 6), driven by the minute wheel, makes one turn in 24 hours and carries a movable finger, a, which by contact with a pin moves the armed lever D by its extremity p. This lever, which has its centre of motion at i, acts through its different arms. Firstly at c it moves the day of the week star wheel (7 teeth). Secondly,

at b the star wheel for the day of the month (31 teeth). The finger a makes engagement and passes one tooth each day of the star wheel E (59 teeth), for showing the phases of the moon.

The part of the mechanism which renders the calendar perpetual is composed of a wheel of 31 teeth F, engaging with

NOTE. -For this arrangement, which is, I believe, the invention of Mr. C. H. Audemars, I am indebted to the fourna Suisse dhorlogerie. the star wheel c. This wheel, which makes one turn per month, passes at each turn, by means of the movable finger n, one tooth of the star wheel G (48 teeth), which latter by this means makes a revolution in four years. The circumference of account disc fixed to this star wheel corresponds to the months of 31 days, the shallowest notches to those of 30 days, and the four quarter notches to the month of February. At e, which is for February in leap year, the notch is hardly so deep as the other three quarter notches.

Each day, after moving the day of the week and the day of the month, the lever D, solicited by the spring h, returns its arm r to rest on the circumference of the count disc or in one of its notches according to the position of the disc.

The point of the piece u pressed by its spring rests on the snail k. Before the last day of the month it falls on to the small part of the snail, and then its action is substituted for that of the arm b ; the point of the piece u presses against the notch of the snail, and advances the star wheel the number of teeth necessary for the hand to indicate the ist of the following month. It will be understood that the distance the point of the piece u falls is regulated by the position of the arm r on the disc or in one of its notches.

In the engraving the mechanism is set to the ist December of the second year after leap year. The two pieces m and t are at the disposition of the watch wearer; the first for adjusting the day, and the second for the age of the moon. The finger a is movable, to permit of putting the hands back without fear of deranging the mechanism. When the wheel H is turned back, the finger is arrested by the arm p, and, as it is sloped at the back, the pin carried by the wheel is able to pass easily, because the flexibility of the piece s permits it to give a little. The wheel should be the same diameter as the star wheel c.

Claims

CLAIMS 1. A device for displaying a monthly calendar comprising two wheels of 35 positions driving two discs, one displaying the days of the week, the other displaying the dates of the month.
2. A device as claimed in claim 1 where the discs are concentric.
3. A device as claimed in any preceding claim where a mask hides the dates 29,30, 31 when they are not appropriate for the current month.
4. A device as claimed in any preceding claim where a pointing device indicates the current date.
5. A device as claimed in any preceding claim where the position of the discs are set by an appropriate adaptation of Brocot's perpetual calendar mechanism
6. A device as claimed in any preceding claim where the position of the discs are set by an appropriate adaptation of Audemars'perpetual calendar mechanism
7. A device claimed in any preceding claim where a mask hides all but one seventy-two degree sector of the discs.

5. A device as claimed in any preceding claim where the position of the discs (and the mask, if employed) are set by an appropriate adaptation of Brocot's perpetual calendar mechanism 6. A device as claimed in any preceding claim where the position of the discs (and the mask, if employed) are set by an appropriate adaptation of Audemar's perpetual calendar mechanism.

7. A device as claimed in any preceding claim where discs are linked directly to the wheels.

8. A device as claimed in any preceding claim where discs are linked to the wheels in such a manner that one turn of a wheel results in five turns of its disc. Amendments to the claims have been filed as follows 1. A device for displaying a monthly calendar comprising two wheels of 35 positions driving two discs, one displaying the days of the week, the other displaying the dates of the month wherein the dates are displayed in a spiral fashion such that each date from eight onwards lies radially inline with the date seven days prior.

2. A device as claimed in any preceding claim where the discs are concentric.

3. A device as claimed in any preceding claim where a third disc hides the dates 29,30, 31 when they are not appropriate for the current month.

4. A device as claimed in any preceding claim where a pointing device indicates the current date.