Timepiece of the mechanical and/or electromechanical type having automatic backward moving display means

A timepiece including automatic backward moving display means. Such invention includes: a horometric movement, an intermediate wheel (22) driven by the movement and including driving gear teeth (26a-26y), a display system (16) for information such as the date, at least one oscillating element (30) coupled to the display system (16) and including driven gear teeth (32) in mesh with the driving gear teeth (26a-26y) of the intermediate wheel (22), return means (34) for the oscillating element (30), declutching means (40, 40a) to enable the oscillating element (30) to effect a free backward motion, and an abutment (B) associated with a counter-abutment (CB) in order to limit the backward movement of the oscillating element (30), this invention being characterized in that the counter-abutment (CB) is formed by one (26a) of the driving gear teeth (26a-26y) of the intermediate wheel (22) which, during driving, normally meshes with the driven teeth (32) of the oscillating element (30).

The present invention concerns a timepiece of the mechanical and/or 
electromechanical type. 
More specifically, it concerns a timepiece including automatic backward 
moving display means, that is to say, adapted to return in reverse 
operation towards a point of origin after having effected a predetermined 
displacement over a course, for example circular in nature. 
Displays of this type are employed to provide analogue information such as, 
for example, hours, minutes, seconds, the date or similar. 
Such display means are also known in horology under other denominations 
such as sectorial or oscillating display means. 
BACKGROUND OF THE INVENTION 
From patent CH-27961 there is known a timepiece including backward moving 
display means which permit reading of hours and minutes on circular arcs 
provided on a dial by means of two hands returning to their point of 
origin after having attained the respective divisions 12 and 60. Such 
timepiece responds to the definition given hereinabove. 
Such piece includes a first driving intermediate wheel formed by a gear 
which is controlled by an entirely mechanical horometric movement and 
which meshes with a toothed sector, itself in mesh with a wheel fixed to a 
pipe bearing a minutes hand. The hours hand is borne by another pipe which 
in this case is directly arranged on a sector meshing with a second 
intermediate wheel. 
Each intermediate wheel includes in its thickness a cut-out formed by a 
notch in the form of a thumbnail. Such notch opens out radially at the 
periphery of the intermediate wheel near the teeth thereof intended to 
mesh with the sector. 
Thus, after each complete rotation in a first sense referred to as driven 
sense, the cutout appears facing the sector which is thus liberated from 
the intermediate wheel and which, thanks to an elastic return means, 
effects an automatic displacement in a rotation sense opposite to the 
first. Furthermore, the sector includes an abutment while the intermediate 
wheel includes a counter-abutment, such abutment and such counter-abutment 
being formed so as to come into contact in order to limit the angular 
displacement of the sector and to readjust precisely the corresponding 
hand onto its original position relative to the dial. The abutment which 
is provided on the sector is formed by a heel the height of which is twice 
that of the teeth and thus to that of the body of the sector. The 
counter-abutment is formed by a tooth of the intermediate wheel which is 
located above the cutout at a level superior to the gear teeth of the 
sector. 
It is thus understood that the intermediate wheel must exhibit a sufficient 
thickness in order to be able to accommodate the cutout arranged therein 
and in order to allow a tooth forming a counter-abutment to remain which 
is sufficiently rigid in shear to accept the dynamic effort provoked by 
the contact of the abutment formed by the heel at the end of the 
displacement in the reverse sense. 
It is also understood that the heel itself must exhibit a sufficient 
thickness or project sufficiently from the gear teeth of the sector in 
order to come into cooperation with the counter-abutment. 
Thus, this arrangement exhibits the primary difficulty of being relatively 
cumbersome in thickness. Such arrangement had been conceived for 
application to a timepiece movement such as a large clock and it is the 
reason for which the designers of that time had not been particularly 
preoccupied with diminishing the thickness thereof. This arrangement thus 
may not be incorporated into a modern mechanical and/or electromechanical 
timepiece in which, as is known, it is furthermore necessary to provide 
space for other large volume components such as the battery or additional 
mechanisms for indication of the date, indeed of a chronograph. 
Furthermore, this prior arrangement requires machining of the intermediate 
wheel for effecting the cutout in form of a thumbnail. This special 
operation as well as that for forming the heel are expensive and increase 
substantially the price of the timepiece so equipped. 
Furthermore, there is known, according to patent CH-143 441, a timepiece 
one hand of which, in particular that of the hours, is also mounted fixed 
to a toothed sector which is intended to cooperate with an intermediate 
wheel in which is arranged a cutout also formed by a notch in the form of 
a thumbnail directly machined in the intermediate wheel. In this 
arrangement the abutment and counter-abutment are constituted respectively 
by a beam of substantial length and by an axis which are respectively 
mounted on the toothed sector and on the intermediate wheel. The axis is 
arranged in a tangential fashion to the cutout. 
There also, the abutment and the counter-abutment project axially from the 
sector and from the intermediate wheel and in thickness occupy a 
substantial amount of space. 
Finally, from patent CH-61 478 there is known a date display watch, one 
hand of which is mounted on a date wheel from which a certain number of 
teeth are lacking, such wheel being driven in rotation through a pin 
mounted on an intermediate wheel. 
Thus, when the hand has finished its course in the sense of the driven 
displacement, the pin is located within the cut-away portion formed by the 
absence of teeth on the date wheel and the motion of such wheel as well as 
that of the hand are stopped in the absence of meshing with the 
intermediate wheel. Additionally, the date wheel meshes with a manually 
operated wheel on which is arranged a bare sector, the diameter of which 
is substantially identical to the diameter at the tips of the teeth of the 
manually operated wheel. This latter permits, in view of its bare 
non-toothed portion, to form an abutment limiting the angular displacement 
of the date wheel. 
Thus, this arrangement is not automatic and necessitates the use of an 
additional operating wheel which, there as well, increases the costs of 
manufacture. Furthermore, such wheel does not permit assuring sealing and 
exposes the movement to dust and impurities since it projects from the 
case in order to be accessible from the exterior. One may also observe 
that the intermediate wheel must show a substantial reduction ratio since 
it must effect one revolution for each step of the date hand, this because 
of the driving pin. 
Thus, the present invention has as its purpose to overcome the difficulties 
of the prior art mentioned hereinabove in furnishing a timepiece provided 
with display means having an entirely automatic backward motion and of the 
least possible thickness in order to diminish the height, in particular, 
so as to be adapted to equip standard movements of a predetermined 
thickness. 
The present invention has also as purpose to furnish a timepiece of this 
type, the cost of manufacture and assembly of which are as low as 
possible. 
SUMMARY OF THE INVENTION 
To this end, the present invention has as object a timepiece of the 
mechanical and/or electromechanical type comprising: 
a horometric movement, 
an intermediate wheel driven by the horometric movement and including gear 
teeth, 
automatic backward moving display means including: 
a display system for information such as the date, for example, 
at least one oscillating element associated with said display system and 
including gear teeth, the gear teeth of the intermediate wheel being 
adapted to come into mesh with the gear teeth of the oscillating element 
so as to drive it in rotation, the gear teeth of the intermediate wheel 
and those of the oscillating element being respectively driving and driven 
teeth, 
return means for the oscillating element, 
declutching means for interrupting, in at least a temporary manner, meshing 
between the driving teeth and the driven teeth and in order to enable the 
oscillating element to effect a free backward motion, said declutching 
means being formed by at least one cut-away segment formed in the driving 
teeth, and 
an abutment associated with a counter-abutment to limit the backward 
movement of the oscillating element, said abutment being fixed to the 
oscillating element while the counter-abutment is fixed to the 
intermediate wheel, being characterized in that said counter abutment is 
formed by one of the driving teeth of the intermediate wheel which, during 
driving, normally meshes with the driven teeth of the oscillating element. 
According to a special embodiment, the cut-away segment which constitutes 
the declutching means as defined in length primarily by two of the driving 
teeth referred to as end teeth, one of these end teeth forming said 
counter-abutment. 
According to still another characteristic of the invention, the driving 
tooth forming the counter-abutment shows at least in plan view a form 
identical to and a thickness equal to those of the other driving gear 
teeth. 
Furthermore, the abutment projects substantially beyond the height of the 
driven teeth of the oscillating element in order to come into cooperation 
with the driving gear tooth forming the counter-abutment. 
But the invention will be best understood upon reading the detailed 
following description, taken with reference to the attached drawings which 
are given solely by way of example.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to FIG. 1, there will be described hereinafter sectorial date 
display means or display means with backward motion indicated by the 
general reference 1. The display means 1 which equip a timepiece 
referenced P are intended to furnish information in an analogue form such 
as the date and, in particular, the day numbers. 
The timepiece P is, in this example, constituted by a wristwatch of the 
mechanical and/or electromechanical type including a bracelet 2 which here 
is partially shown and which is assembled on case 4. 
The timepiece P includes a dial 6 on which are inscribed in particular 
hours and minutes indications identified respectively by a first group of 
numbers 1 to 4 and 8 to 12 and by a graduated circular scale, not 
referenced. Facing dial 6 are arranged three hands, respectively hours 
hand 8, minutes hand 10 and seconds hand 12 which are driven by a 
horometric movement, not shown, assembled in a standard manner in the case 
4 and being manually actionable by a crown 14. Hands 8, 10 and 12 may be 
moved in rotation in a coaxial manner around a first rotation axis X1, 
centered on the movement of timepiece P. 
The sectorial or backward moving display means 1 according to the invention 
include in a manner visible on this figure, an information display system 
16 which is constituted by a hand 18 formed so as to be angularly 
displacable facing an annular sector 20 on the interior of which are 
inscribed data and in particular in this example a second group of odd 
numbers 1 to 31 indicating the day numbers of the month. 
As will be understood hereinafter, hand 18, which is kinematically coupled 
to the horometric movement of the timepiece P, is located in its starting 
position the first day of the month facing indication 1, and it jumps one 
step each day, in particular around midnight thanks to means which for the 
most part are standard and which will not be here described in detail. 
In the simplest version of the timepiece according to the invention, the 
date hand 18 continues its advance until it comes to face FIG. 31 where it 
attains its final angular displacement position. 
Instead of effecting a following step, hand 18 is automatically displaced 
in the reverse sense towards its original position. Such hand 18 thus 
effects a backward movement. Such movement being effected solely over a 
fraction of a revolution, and in particular in this example over an angle 
of about 330.degree., it is understood why the display means 1 according 
to the invention are also qualified as sectorial display means. 
Referring hereinafter to FIGS. 2 and 3, there will be described in the most 
detailed manner the mechanical arrangement of the display means according 
to the invention. 
On these figures, dial 6 as well as a support plate 50 have been shown 
partially and cut away. There are also found on these figures hand 18 
which here is shown in broken outline. 
Display means 1 according to the invention include an intermediate wheel or 
driving pinion 22 which is mounted for rotation around a central axis X1 
and which is fixed to a driving star 24 including in this example 31 
teeth. Such star is controlled in a standard manner by the horometric 
movement, not shown, and it is associated with a jumper spring, also well 
known, and likewise not shown. 
The intermediate wheel 22 includes gear teeth 26a, 26b up to 26y, in this 
example to the number of 25, such teeth being indicated by the general 
reference 26a-26y (26a to 26y). 
The sectorial or backward moving display means 1 further include an 
oscillating element 30 which is associated with the display system 16 
through an axis, not referenced, on which is driven hand 18 in a standard 
manner. 
Oscillating element 30 is constituted by a wheel and in particular by a 
date wheel (same reference) which is mounted for rotation around a second 
rotation axis X2 separated from the first X1 and which includes gear teeth 
indicated by the general reference 32. 
As may be seen more specifically on FIG. 3, the gear teeth 26a-26y of 
intermediate wheel 22 are adapted to come into mesh with the gear teeth 32 
of the oscillating element 30 in order to drive it in rotation over a 
fraction of an angle corresponding to the arc of the annular display 
sector 20. The motor couple being received from the movement of the 
timepiece P via intermediate wheel 22, it is understood that the gear 
teeth 6a-26y of intermediate wheel 22 and the gear teeth 32 of the 
oscillating element 30 are respectively driving and driven teeth. 
Furthermore, display means 1 include elastic return means for oscillating 
element 30, such means 34 being constituted by a spiral spring (same 
reference) one end of which is fixed to the oscillating element 30 in 
being secured for example on its non-referenced support axis while the 
other end is maintained fixed relative to the case by being directly 
secured for example on the support plate 50 shown in greater detail on 
FIGS. 5 to 8. The return means 34 are arranged in a manner such that 
oscillating element 30 is elastically returned towards its original 
position shown on FIG. 2, that is to say, in its backward motion sense (in 
this example, counter-clockwise). 
Display means 1 further include declutching means 40 formed to interrupt in 
at least a temporary manner meshing between the driving teeth 26a-26y and 
driven teeth 32 and, as will be understood, in order to permit the 
oscillating element 30 to freely effect its return motion. 
The declutching means 40 are constituted by a cut-away segment (same 
reference) formed in the driving teeth 26a-26y. Such cut-away segment 40 
corresponds thus to a zone without teeth forming an annular bare or smooth 
sector, on intermediate wheel 22. 
Thus, in the position shown on FIG. 2, teeth 32 of the oscillating element 
30 are no longer meshing normally with those 26a-26y of intermediate wheel 
22. Thus, when the cut-away segment 40 comes to face the driven teeth 32, 
the oscillating element 30 is disengaged from its kinematic coupling with 
intermediate wheel 22 and hence with the horometric movement of the 
timepiece P according to the invention. 
At the same time, oscillating element 30 is permanently elastically urged 
by spring 34 towards its original position in a counter-clockwise moving 
sense and its angular displacement in such sense is limited at the 
original position by an abutment B and by a counter-abutment CB of the 
display means 1 according to the invention. 
Abutment B is fixed to oscillating element 30 while the counter-abutment CB 
which is formed by one (referenced 26a) of gear teeth 26a-26y, is fixed to 
intermediate wheel 22. 
Thus, the counter-abutment CB in being constituted by tooth 26a of the 
driving gear teeth 26a-26y on intermediate wheel 22, normally meshing 
during driving with driven teeth 32 of the oscillating element 30, does 
not require any additional machining or assembly operation, in particular 
on intermediate wheel 22. 
The cut-away segment 40 which constitutes the declutching means shows an 
arc length, not referenced, primarily defined by two of the driving teeth 
respectively 26a and 26y referred to as end teeth, one, 26a, of such end 
teeth forming in particular said counter-abutment CB. 
It will be noted on the figures that the driving tooth 26a forming the 
counter-abutment CB has at least in plan view a form identical to that of 
the other driving gear teeth 26b to 26y. More specifically, it will be 
specified that such tooth 26a shows a thickness equal to that of the other 
driving gear teeth 26b to 26y. 
As to the abutment B, this projects substantially beyond the driven teeth 
32 of the oscillating element 30 in their height h (FIG. 2) in order to 
come into cooperation with tooth 26a forming the counter-abutment CB. 
It will also be specified that, as is seen on figure 3A, abutment B is 
arranged primarily in the thickness of the oscillating element 30. 
More specifically and as is seen on this figure, abutment B shows a 
thickness E1 equal to that E2 of teeth 32. 
FIG. 4 shows a second embodiment of the invention in which the intermediate 
wheel 22 includes two groups G1 and G2 of driving teeth, such groups being 
separated by an equal number of cut-away segments respectively 40 and 40a. 
The angular course of hand 18 is thus here much more limited and this hand 
effects two advances and returns for a single complete rotation of the 
intermediate wheel 22. The number of cut-away segments as well as the 
number of distinct groups of driving teeth are not limited to two and may 
be respectively extended to larger numbers. 
It may be specified that in all the examples described and as is seen on 
FIG. 3A, abutment B as well as the driven gear teeth 32 of the wheel 
forming the oscillating element 30 are cut in the thickness E2 of the 
plate P forming said wheel. The abutment B may thus be arranged by the 
same operations of machining and stamping as those necessary to forming 
teeth 32 without additional operations. 
Furthermore and as is seen on FIGS. 2 and 4, abutment B includes a profile 
showing a lateral re-entrant flank FL (FIG. 3) adapted to cooperate with 
the driving tooth 26a forming the counter-abutment B. Thus, when hand 18 
is brought back to its original position following its backward motion, 
oscillating element 30 is again driven in rotation in the clockwise sense 
thanks to the action of tooth 26a on the re-entrant lateral flank FL. 
It is furthermore seen that abutment B is constituted by a segment S 
projecting from the summit of two half-teeth from the driven teeth 32 of 
the oscillating element 30. 
Abutment B is obtained simultaneously with formation of the driven gear 
teeth 32 of the oscillating element 30. For this, the wheel forming such 
oscillating element 30 is cut out to an exterior diameter greater than the 
diameter at the tips of teeth 32. This additional diameter corresponds to 
twice the height H (FIG. 3) of abutment B. Thereafter, teeth 32 are formed 
in plate P with the help of a standard milling cutter, not shown, but only 
over a given angular portion in order to allow abutment B to remain and to 
appear in wheel 30. 
The invention further includes a support plate 50 shown in a more detailed 
manner on FIGS. 5 to 8, on which is rotatably mounted the oscillating 
element 30. 
Such support plate 50 is intended to be assembled and secured by its lower 
face F1 (FIGS. 6 and 7) on a base plate of the horometric movement, not 
shown, of the timepiece P according to the invention. Such plate 50 
includes two cutouts 52 and 54 opening radially into one another. The 
first cutout 52 receives the intermediate wheel 22 while the second 54 
receives the oscillating element 30. To this end the second cutout 54 
includes a tongue or projection 56 on the free end of which oscillating 
element 30 is supported in cantilever and for rotation. Tongue 56 projects 
diametrally in the second cutout 54 towards the center thereof so as to 
come into coincidence with the second rotation axis X2. 
It will be noted that plate 50 includes a third cutout 59 arranged at the 
side of face F1 and in which open out axially the other two cutouts 52 and 
54. 
As is seen on FIG. 9, the invention further includes a second plate 60 
fastened onto the first plate 50. 
Such second plate 60 is secured by systems of screws and threads 62 above 
the oscillating element 30 in a fourth cutout 58 provided in the first 
plate 50, above the second cutout 54 and in a manner coaxial to the 
latter. 
The second plate 60 includes an open circular slot 64 in which there may be 
introduced a tool, not shown, intended to cock the oscillating element 30 
by placing under tension its return means 34.