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Description  |
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The invention relates to an annual calendar mechanism for a timepiece, said
mechanism comprising a date ring provided with thirty one internal teeth
inside the ring, onto which are applied thirty one numbers each
corresponding to a day of the month which appear successively through a
window made in a dial, and a calendar driving wheel set making one
rotation in twenty four hours, said wheel set having a first finger
capable of driving the date ring through one step once each day via one of
its internal teeth, said wheel set controlling the calendar display.
A calendar mechanism answering generally to the definition which has just
been given is known for example from patent documents CH 538 136 and CH
661 171 (US 4,676,659). In these documents, there is also found a twenty
four hour calendar driving wheel provided with a finger or a long tooth
which drives a date disc bearing thirty one indications. However, the
finger does not directly drive the disc but rather an intermediate wheel
set which itself drives such disc. In this case, of course, it concerns an
ordinary calendar mechanism, not an annual or perpetual calendar. At the
end of months of thirty days and at the end of the month of February, it
thus necessary to effect a manual correction should one not wish to lose
the date.
A description of different types of calendar mechanisms in watches is given
in the work entitled "Les montres calendrier modernes" by B.
Humbert--Editions Scriptar S. A. Lausanne 1953 (English version: "Modern
calendar watches", Lausanne 1954).
Patent document DE 2 311 539 discloses a calendar mechanism using a month
cam making one rotation a year. Such cam has notches which are more or
less deep: the full portions correspond to months of thirty one days; the
shallow notches to months of thirty days; and a very deep notch to the
month of February in the common years (twenty eight days). The beak of a
lever urged by a spring acts on such cam. The depth of penetration of the
beak will determine which advance must be imparted to the date indicator
via a lever at the end of each month.
The mechanism briefly mentioned herein before uses levers and return
springs, which lead to a relatively complicated construction which in turn
necessitates a relatively high number of parts. On the other hand, it can
be mentioned that such lever mechanisms do not always exhibit reliable
operation, particularly if shocks are applied to the timepiece.
A perpetual calendar mechanism comprising relatively few parts is disclosed
in patent DE 449 081. Several coaxial superposed discs, bearing
respectively the indications of the days, the date from 1 to 15, the date
from 15 to 31, the months and the years, have respective central apertures
having toothings certain of which have variable teeth height. Such
toothings are driven by two clicks carried by a movable part which pivots
back and forth. One of the clicks has a flexible bent end which, by
bearing against a toothing of variable height which acts as a cam, either
drives or does not drive the second date disc in the last days of the
month. The month disc carries a sliding spring which drives the first date
disc to put it back into operation again when the month changes. Despite
its apparent simplicity, this mechanism is thick, delicate and has not
been widely used. Furthermore, it requires a reciprocating driving which
necessitates an additional mechanism in a timepiece.
In order to obviate the cited drawbacks, the present invention proposes to
use only gears to the exclusion of any levers or rocking bars, such gears,
on the one hand, being prevented from making any untimely rotation, even
if shocks are applied to the timepiece and, on the other hand, having a
clearly simplified design and a reduced height, this being even more so
the case since the calendar of the invention is limited to the automatic
advance of the date for the months of thirty days only, the resetting of
the date having to be effected manually at the end of the month of
February. Hence, it concerns an annual and not a perpetual calendar.
An annual calendar in which a manual correction remains necessary at the
end of the month of February has already been proposed and described in
patent document CH 684 815. In this document, the annual calendar
mechanism comprises a calendar driving wheel fitted with a finger capable
of driving a date wheel through one step at the end of every day. An
annual wheel, driven once a month through two steps by a long tooth
carried by an intermediate wheel which itself engages with the date wheel,
comprises a plate having five teeth each corresponding to one of the
months of less than thirty one days. When one of these five teeth appears
in the path of the finger, the annual wheel, from being driven itself,
becomes a driving wheel and drives the date wheel through an additional
step via the intermediate wheel.
Although having a clearly simplified design and a reduced height compared
to a perpetual calendar, the mechanism which has just been described in
summary hereinabove necessitates the provision of numerous new parts. It
also necessitates a significant transformation of a basic movement which
one would wish to modify as inexpensively as possible.
In order to overcome these drawbacks and thus to propose an annual calendar
mechanism easily adaptable to a conventional movement, at the same time
necessitating a minimum of new parts, the present invention is
characterised in that, from the known features defined in the first
paragraph of this description, the mechanism additionally comprises an
annual ring superposed on the date ring, making one rotation in a year and
fitted with external teeth in positions corresponding to the twelve months
of the year and five internal teeth in positions corresponding to the
months of less than thirty one days, said annual ring being arranged
off-centre with regard to the date ring and next to the calendar driving
wheel set so that it is actuated, at the end of months of less than thirty
one days, by a second finger of the calendar driving wheel set, such
second finger acting on one of the five internal teeth of the annual ring,
engaging means fixed to the date ring being used to engage, at the end of
each month, said date ring with said annual ring via at least one of said
external teeth.
There results a mechanism whose movable parts are all rotatable and are
only three in number, namely the driving wheel set, the date ring and the
annual ring. These movable parts may be arranged on only two levels, that
of the date ring and that of the annual ring passing above or below the
latter. It is thus possible to realise the calendar mechanism in the form
of a module of small thickness, which can be superposed on an ordinary
watch movement. Furthermore, the off-centre arrangement of the annual ring
offers, if such ring bears the month indications, great freedom of choice
as to the position of the window where these indications appear, in
particular at different distances from the centre of the clockwork
movement and the dial. In particular, the annual ring may be arranged
off-centre with regard to such centre and be large enough to pass around
it, i.e. around the shafts of the hands of a conventional analogue display
.
The invention will now be explained with the aid of the description which
follows and the drawings which illustrate it by way of example, in which:
FIG. 1 is a top view of a watch having an annual calendar according to the
invention;
FIG. 2 is a top view of the annual calendar mechanism fitting the watch of
FIG. 1, this figure illustrating the situation of wheels on 30 April at 23
hours and 45 minutes;
FIG. 3 is a similar view to that of FIG. 2, the situation of the wheels
being that shown on 1st May at 0 hours and 15 minutes;
FIG. 4 is a similar view to that of FIG. 2, the situation of the wheels
being that shown on 1st May at 4 hours;
FIG. 5 is a cross-section along the line V--V of FIG. 2, and
FIG. 6 is a top view of the annual crown wheel of FIG. 2 which explains the
function of such crown wheel with regard to the months of the year.
The top view of FIG. 1 shows a watch fitted, apart from the hours hand 70,
the minutes hand 71 and the seconds hand 72, with a date indicator in the
form of a date 3 appearing through a window 4 made in a dial 5. Time
setting may be effected by means of a control crown 61. If the dial is now
removed from this watch and only the elements useful for realising the
invention are kept, one ends up with the top views of FIGS. 2, 3 and 4
which show the mechanism in question at three different moments during the
passing from the month of April to the month of May.
Examination of FIG. 2 and the cross-section of FIG. 5 in particular will
help the annual calendar mechanism according to the invention to be
understood. This mechanism comprises a date ring 1 fitted with thirty one
teeth 2. Thirty one numbers 3 are applied onto ring 1 each corresponding
to a day of the month. These numbers appear successively through window 4
made in dial 5 shown in FIG. 1. A calendar driving wheel set, globally
designated by the reference 6, is fitted with a first finger 7 capable of
driving date ring 1 through one step once a day via one of its internal
teeth 2. In the particular case shown in FIG. 2, first finger 7 has just
come into contact with tooth 2a and will thus cause ring 1 to advance
through one step from 30 to 31 as is shown eventually in FIG. 3. As is
seen in FIGS. 2 to 4 and better still in the cross-section of FIG. 5,
driving wheel set 6 comprises a driving wheel 21 which connects this wheel
set to the clockwork movement (not shown here) and makes one rotation in
twenty four hours. The cross-section section of FIG. 5 shows that first
finger 7 of driving wheel set 6 is situated in the path of tooth 2a
belonging to date ring 1. Finger 7 is a protuberance of a disc 22 forced
onto a shaft 23, driving wheel 21 being fixed to the same shaft 23. Via
its pivot 24, shaft 23 can rotate freely in a bearing 25 mounted in the
bottom plate 17 of the timepiece.
What has been described in the paragraph hereinabove is well known from the
state of the art. It concerns the conventional driving of a date ring,
such ring being able to be set to the date by a rapid date-corrector 20
(see FIG. 2) engaged with teeth 2 of ring 1, this date-corrector 20 being
controlled by manual control crown 61 (FIG. 1). In such a conventional
system, date setting is necessary at the end of the months which have less
than thirty one days, namely the months of February, April, June,
September and November.
One will now describe what has been added to this conventional mechanism to
transform it, according to the invention, into a mechanism called an
annual mechanism in the sense that the date jumps from 30 to 1st at the
end of months of less than thirty one days.
In addition to what has been enumerated hereinabove, the mechanism
according to the invention comprises an annual ring 8, as drawn in FIGS. 2
to 6. This annual ring is superposed on date ring 1 and makes one rotation
in a year. Annual ring 8 is fitted with twenty four teeth 9 uniformly
distributed on its external periphery, such external teeth 9 corresponding
in pairs to the twelve months of the year, and with five teeth 10 on its
internal periphery, such internal teeth 10 each corresponding to months of
less than thirty one days. FIGS. 2 to 4 show that annual ring 8 is
arranged off-centre with regard to date ring 1. It is also arranged in
such a way that it is actuated at the end of the month having less than
thirty one days, by a second finger 11 of calendar driving wheel set 6,
this second finger 11 acting on one of said five internal teeth 10 of ring
8. In the particular case shown in FIG. 3, second finger 11 has just come
into contact with tooth 10a of annual ring 8 and will cause said ring to
advance through one step (one twenty fourth of a rotation or 15.degree.)
from IV to V as is shown in FIG. 4. As is clearly seen in the
cross-section of FIG. 5, second finger 11 of wheel set 6 is a protuberance
of a disc 26 forced onto shaft 23, disc 26 being mounted above disc 22
which has already been described and being separated from the latter by a
spacer 27. The cross-section of FIG. 5 clearly shows that second finger 11
of driving wheel set 6 is situated on the path of tooth 10a belonging to
annual ring 8. It will be noted however that finger 11 could be carried by
the same disc 22 as finger 7, so that members 26 and 27 could be omitted.
FIGS. 2 to 4 show finally that engaging means 12, 13 fixed to date ring 1
are used for engaging or coupling, at the end of each month, said date
ring 1 with said annual ring 8 via one of its twenty four external teeth
9.
The aforecited engaging means could consist of a single pin mounted at the
periphery of date ring 1, or a cut and folded part of the edge of such
ring, this pin or folded part engaging in twelve slits arranged on the
periphery of the annual ring, such slits being separated by full parts
acting as teeth. The use of two pins or catches 12 and 13 mounted
perpendicularly on the periphery of ring 1 has, however, been preferred,
such pins being arranged so that the circumferential length X (see FIG. 2)
taken by the two pins is substantially equal to the empty space Y
separating two successive external teeth 9a and 9b of annual ring 8. In
any case, the respective diameters of ring 1 and ring 8 are selected so
that at each change of month, ring 8 is driven through two twenty fourths
of a rotation (30.degree.) by date ring 1. Likewise, the internal diameter
of ring 8 will be selected so that internal teeth 10 co-operate with
second finger 11 also enabling the co-operation of first finger 7 with
teeth 2 of date ring 1.
FIGS. 2 to 5 also show that annual ring 8 pivots about a guide disc 16
fixed onto bottom plate 17 by means of two screws 28 and 29 (see FIGS. 2
to 4). The same figures also show that a first jumper spring 18 abuts
between two successive teeth 2 of date ring 1 and that a second jumper
spring 19 abuts between two successive external teeth 9 of annual ring 8.
These jumper springs enable ring 1 and ring 8 to be angularly positioned
at rest. It is because of jumper spring 19 that ring 8 comprises twenty
four external teeth 9, to define its twenty four successive positions,
whereas twelve teeth would be sufficient to co-operate with pins 12 and
13. It will be noted finally that twenty four indications 14, chosen here
as roman numerals, are applied onto ring 8, arranged in pairs and
identifying the months of the year, such indications appearing through a
window 15 arranged in dial 5 as is shown in FIG. 1. In the figures, the
date appears at 3 o'clock and the month at 9 o'clock. This display could
appear in other places, for example the date at 12 o'clock and the month
also at 12 o'clock but underneath.
FIG. 2 also shows that it is possible to provide a rapid month corrector 40
which preferably has two teeth engaging external teeth 9 of annual ring 8,
to cause it to go back two steps per rotation of corrector 40. When
control crown 61 is in a pulled out position, the rotation of the latter
in a first direction actuates corrector 40, and in the other direction it
actuates corrector 20. The principles of such correction mechanisms are
known and do not need to be described here.
According to an alternative embodiment, guide disc 16 may be replaced by a
fixed guide ring 32 (a fragment of which is shown in dash lines in FIG. 2)
which surrounds and guides the periphery of annual ring 8, for example
partially covering teeth 9. This alternative embodiment enables screws 28
and 29, situated inside the clockwork movement, to be replaced by screws
or other fixing elements situated on the periphery of such movement and
the calendar mechanism. This facilitates the application of the mechanism
according to the invention in the form of a separate module which can be
mounted without difficulty on different clockwork movements, having, in
particular, different bottom plates.
It will be noted that with each of both guiding forms described
hereinabove, off-centre annual ring 8 may be large enough to extend around
the axis of rotation 33 (FIG. 5) of date ring 1, and thus also around the
central shafts 34, 35 and 36 carrying the second, minute and hour hands in
a conventional timepiece, as shown in the drawings. There result multiple
possibilities for combining different relative positions of windows 4 and
15 where the date and the month respectively appear. Furthermore, annual
ring 8 may be sufficiently wide to carry the names of the months in full
or in abbreviated form. Finger 11 may be situated on a smaller radius than
that of finger 10.
Another possibility for indicating the month consists in applying an index
on annual ring 8, for example, a coloured index which is visible through a
discontinuous circular slit or a circular row of apertures arranged in the
dial above the annual ring, the names or numbers of the months being then
marked on the dial. Since this display device is able to be arranged
off-centre on the dial, it offers interesting possibilities of a
decorative and aesthetic nature.
The different elements forming the invention and the manner in which they
interact having been defined hereinabove, the operation of the annual
calendar mechanism remains to be explained. Two cases may occur according
to whether months of less than thirty one days or months of thirty one
days are concerned.
The passing from 30th to the first day of the following month in the case
of a month of less than thirty one days is illustrated in FIGS. 2, 3 and
4. FIG. 2 shows the mechanism as it appears on 30 April (a month of 30
days) when its hours hand 70 and minutes hand 71 indicate 23 hours and 45
minutes. At this moment the date displayed is 30 and the month displayed
is the first indication IV (April). Pins 12 and 13 of ring 1 are almost
engaged between teeth 9a and 9b of annual ring 8. Likewise, first finger 7
of driving wheel set 6 comes into contact with tooth 2a of ring 1. In FIG.
3, the same mechanism is seen when hours hand 70 and minutes hand 71
indicate 0 hours and 15 minutes on the 1st of May. First finger 7 of wheel
set 6 has driven date ring 1 through one step, via tooth 2a, such ring
then displaying the date 31 (momentarily). Annual ring 8 has been advanced
through one step by pin 12 acting on tooth 9b, this ring displaying the
second IV (momentarily). Second finger 11 of wheel set 6 comes into
contact with tooth 10a of ring 8. In FIG. 4, the same mechanism is seen
when hours hand 70 and minutes hand 71 indicate 4 hours and 0 minutes the
1st of May. Ring 8 has been driven through one step by second finger 11 of
wheel set 6 and now displays the first indication V (May). Said ring 8,
from being normally driven by ring 1, has become a driving wheel through
the action of finger 11 and then drives, via its tooth 9a, date ring 1 via
pin 13. Ring 1 displays, at the end of its travel, the FIG. 1. Once this
phase has ended, pins 12 and 13 are disengaged from teeth 9a and 9b and
ring 1 can continue its rotation day after day. In order not to mislead
the wearer of the watch, one could replace the second indication of months
of less than thirty one days (i.e. II, IV, VI, IX and XI) by a coloured
point or an empty space.
The passing from the 31st to the 1st day of the following month in the case
of a month of thirty one days is not illustrated in the figures. It will
be understood that in such case none of the five teeth 10 of annual ring 8
is situated on the path of second finger 11 of wheel set 6. For example,
annual ring 8 displays the month of May, namely the first figure V as
illustrated in FIG. 4. At midnight on the 30th May, the date ring jumps to
31 (through the action of first finger 7) and causes annual ring 8 to
advance through one step, such ring then displaying the second V (through
the effect of pin 12). At midnight on the 31st May, the date ring jumps to
the 1st June under the effect of finger 7 and thus causes annual ring 8 to
advance through a new step, ring 8 then displaying the first VI (June)
through the effect of pin 12.
FIG. 6 is a partial resumption of FIG. 2. It shows annual ring 8 in its
entirety and date ring 1 and driving wheel set 6 partially. It can be seen
that internal teeth 10 of ring 8 are arranged around the internal
periphery of said ring successively at 60.degree., 60.degree., 90.degree.,
60.degree. and 90.degree.. If these teeth 10, which represent the months
of February, April, June, September and November, are situated on the path
of second finger 11 of wheel set 6, the date will pass rapidly, at the end
of these months, from 30 to 31, then from 31 to the 1st of the following
month, as has been explained hereinabove.
If the system which has just been described pursues the same aim as that
exposed in the aforecited patent document CH 684 815, it has, compared to
this publication of the prior art, notable simplifications in the reduced
number of parts which it uses and in the minimum space requirements which
it proposes. Indeed, the only significant new parts are annual ring 8 and
second driving finger 11. This system thus sees the timepiece thicken only
by the thickness of this annual ring. Furthermore, conventional movements
fitted with a single date ring are very easily adapted to this new
calendar.
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