WO2019243943A1

WO2019243943A1 - Digital display for a timepiece

Info

Publication number: WO2019243943A1
Application number: PCT/IB2019/054757
Authority: WO
Inventors: Pascal HUMAIR; Julien Giacobino
Original assignee: Patek Philippe Sa Geneve
Priority date: 2018-06-20
Filing date: 2019-06-07
Publication date: 2019-12-26
Also published as: EP3811157A1

Abstract

The digital display for a timepiece comprises a first indicator disc (31) and a second indicator disc (33) that each bear, in a regular distribution on a peripheral ring, a series of numerals or pairs of numerals. The digital display also comprises a mechanism for driving the second disc (33) by the first disc (31), which mechanism has a toothing integral with the second disc and having one tooth (37, 37a) for each numeral or pair of numerals borne by the second disc (33), and at least one finger (35) integral with the first disc (31) and intended to engage, once per turn of the latter, with a tooth (37a) of the second disc (33) so as to move the second disc on by one step. The drive mechanism is of the Maltese cross type.

Description

Digital display for a timepiece

The present invention relates to a digital display for a timepiece comprising a first indicator disc and a second indicator disc each carrying a series of numbers or pairs of figures regularly distributed over a peripheral ring so as to form at least one ordered sequence, the two indicator discs being arranged so as to selectively present one of the figures or pairs of figures carried by the first indicator disc in association with one of the figures or pairs of figures carried by the second indicator disc, the digital display further comprising a mechanism for driving the second indicating disc by the first indicating disc, the drive mechanism comprising a toothing integral with the second indicating disc, the toothing comprising a tooth for each digit or pair of digits carried by the second indicating disc, and at least one finger attached to the first indicator disc, the doi gt being arranged to engage a tooth of the second indicator disc so as to increment the latter by one step once per revolution.

The invention also relates to a timepiece comprising a digital display conforming to the definition above.

PRIOR ART

There are already known digital displays for timepieces which conform to the definition given above. These known displays have certain faults. In particular, the two discs can become desynchronized, for example under the effect of a shock. Indeed, apart from the moments when the finger of the first disc is engaged in the teeth of the second, no kinematic link connects the two discs to each other. This is the reason why two jumper springs are used to hold the first and second discs in position, and to prevent one of them from accidentally turning. In general, in order to limit the amount of mechanical energy that must be spent to intentionally rotate the discs, jumper springs are used as small as possible. However, when this reduces the retaining force exerted by the jumpers on the discs, there is a significant risk that the display will adjust in the event of an impact.

BRIEF STATEMENT OF THE INVENTION

An object of the present invention is to remedy the drawbacks of the prior art which have just been explained. The present invention achieves this and other objects by providing a digital display according to claim 1 appended hereto.

According to the invention, the drive mechanism of the second disc by the first disc is of the Maltese cross type. As a person skilled in the art knows, a drive mechanism of the Maltese cross type is a mechanical device making it possible to transform a movement of continuous rotation into a jerky rotation. Figure 4 attached shows a Maltese cross drive mechanism of conventional design. The operation of the drive mechanism shown is as follows: a driving mobile 21, which comprises a profiled cam 23 in the shape of an incomplete cylindrical and a lug 25, rotates continuously. The driven mobile (in other words the Maltese cross) 27 has four branches (or teeth). The lug 25 enters the space (or groove) between two branches and rotates the Maltese cross 27 by ¼ of a turn. The driving mobile 21 does not stop rotating so that the lug 25 comes out of the groove. The Maltese cross 27 is then immobilized by the cooperation of the concave top of one of its branches with the cylindrical part of the profiled cam 23. In fact, the shape of the cylindrical part of the profiled cam 23 is complementary to the concave shape from the top of the branches of the Maltese cross 27, so that the profiled cam 23 holds the Maltese cross 27 in a position indexed during periods when the lug 25 is not engaged in one of the grooves.

According to the invention, the teeth of the toothing which is integral with the second indicator disc have a truncated shape with a concave apex. In addition, the digital display includes a cam which is integral with the first indicator disc in the coaxial position. The cam is circular except in the vicinity of each of said at least one finger, where the generally round shape gives way to a hollow cut. The circular profile of the cam is complementary to the concave profile of the top of the teeth of the second indicator disc.

According to the invention, the mechanism for driving the second indicator disc by the first indicator disc keeps the second indicator disc in an indexed position during periods when none of the said at least one finger is engaged in the teeth of the second disc. indicator. An advantage linked to this characteristic is that it is not necessary to use a jumper to index the second indicator disc.

BRIEF DESCRIPTION OF THE FIGURES

Other characteristics and advantages of the present invention will appear on reading the description which follows, given solely by way of nonlimiting example, and made with reference to the appended drawings in which:

FIG. 1 is a plan view on the dial side of a wristwatch which includes an alarm mechanism with means for indicating the alarm time, the latter comprising a digital display conforming to a particular embodiment of the invention. invention;

Figure 2 is a top plan view of a digital display of hours and minutes, which is in accordance with a first particular embodiment of the invention; Figure 3 is a schematic view showing the association of a pair of numbers carried by the first indicator disc and a pair of numbers carried by the second indicator disc;

Figure 4 is a schematic plan view of a prior art Maltese cross drive;

Figure 5 is an enlarged partial view of the digital display of Figure 2 and showing more particularly the finger secured to the first indicator disc and one of the teeth secured to the second indicator disc;

- Figure 6 is a top plan view of a digital display of hours and minutes, which is in accordance with a second particular embodiment of the invention;

Figure 7 is a top plan view of a digital display of the hours and minutes, which is in accordance with a third particular embodiment of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS

The digital display for a timepiece of the invention lends itself to numerous applications: digital indication of the current time (hours and minutes); calendar ; decimal counter linked to a non-hourly function (golf counter for example); etc.

FIG. 1 appended is a plan view on the dial side of a wristwatch which comprises an alarm mechanism with means for indicating the alarm time, the latter comprising a digital display conforming to a particular embodiment of the invention. Certain characteristics of the wristwatch shown, which are related to the invention, will now be described. The watch in Figure 1 has a winding and time setting crown (referenced 11) which protrudes from the middle of the watch at 4 o'clock. When the crown 11 is in the first pulled position, it allows to shift the alarm time in one direction or the other by rotating the crown. The wristwatch also has a digital display intended to indicate the alarm time. This display is in accordance with a particular embodiment of the invention. The digital display is arranged to indicate the alarm time through two counters (referenced 3 and 5) which are arranged side by side in the dial 7 at twelve o'clock. A first of the two windows (referenced 3) indicates the hour as an integer between 1 and 12, and the second window (referenced 5) indicates the minute as a two-digit number. Finally, a third small window (referenced 9) is arranged between the first two windows 3 and 5 and the center of the dial. The indicator that appears in the small window 9 is a day / night indicator associated with the alarm time.

A digital display of the hours and minutes, which conforms to a first particular embodiment of the invention will now be described with reference to Figures 1, 2, 3 and 5.

The display shown has two discs arranged side by side, a minute disc 31 which carries twelve two-digit numbers between 00 and 55 and an hour disc 33 which carries integers from 01 to 12. It will be noted that, so equivalent, an empty space could replace the zero when it is left in a pair of numbers. On the other hand, although the two discs 31, 33 have the same diameter in the example illustrated, it will be understood that they could have different diameters. Conventionally, the two discs 31, 33 are arranged under the dial 7 (FIG. 1) so that only the two numbers which occupy the positions directly opposite one another are visible through the two apertures 3, 5, as shown in Figures 1 and 3.

In accordance with what has been explained above, the wearer of the wristwatch of the present example can actuate the minute disc 31 in rotation, in one direction or the other, using the winding crown and time 11 (figure 1). In addition, in accordance with the invention, the display represented comprises a mechanism for driving the hour disc by the minute disc. The minute disc 31 carries a lug (or finger) 35 which projects radially from its periphery, and the hour disc 33 carries twelve truncated teeth 37 which are regularly spaced along its circumference. The display in this example is designed to take up the least amount of space possible. To this end, the teeth 37 and the disc 33 of which they are integral are arranged on one and the same level, the truncated teeth 37 thus projecting from the circumference of the disc 33. It will however be understood that the teeth 37 could alternately constitute the toothing of a star arranged coaxially under the hour disc. According to this second scenario, the minute disc 31 would preferably be thicker, so that the numbers it carries can be at the same level as the numbers carried by the hour disc, while allowing the lug 35 to be at the same level as the teeth 37.

With particular reference to FIG. 2, it can be seen that the outer edge of the minute disc 31 is formed by an annular zone 39 with a cylindrical outer edge which extends along most of the circumference of the disc 31. FIG. 2 also shows that the twelve truncated teeth 37 each have a concave rounded apex, the curvature of the roundness being complementary to the curvature of the cylindrical outer edge of the annular zone 39. In addition, the distance between the minutes disc and that of the hours is chosen so that the convex cylindrical edge of the minutes disc 31 can fit into the concave rounding presented by the top of a tooth 37. It will be understood that the minutes disc 31 operates at in the manner of a profiled cam in the shape of an incomplete cylinder, the hour disc 33 being kept immobilized while the cylindrical profile cam rotates about its axis.

The annular zone 39 extends along the entire circumference of the disc 31 with the exception of an interruption at the level of the lug 35. Still referring to FIG. 2, it can be seen that the two ends of the annular zone 39, on either side of the lug 35, each have a shape of a gently sloping chamfer, and that the two chamfers which face each other together define a hollow cutout from the bottom of which the lug 35 projection. In the present example, the hollow cut has a symmetrical shape centered on the lug. When, during the rotation of the minute disc, the lug 35 approaches the tooth 37a, the first end of the annular zone 39 passes opposite the concave rounding of the top of the tooth, the outer cylindrical edge gradually giving way to the hollow cut. This change reveals a space between the tooth 37a and the disc 31, so that the hour disc 33 is no longer immobilized (Figure 5).

Then, when continuing on its trajectory, the lug 35 meets the flank of the tooth 37a, it drives it and thus rotates the hour disc 33 by one step, so that the next tooth 37 comes immobilize by bracing against the second end of the cylindrical outer edge of the annular zone 39. The hour disc 33 is therefore again immobilized after having pivoted exactly the angular value of one step of the toothing. It will further be understood that, in accordance with the invention, the mechanism for driving the hour disc 33 by the minute disc 31 keeps the hour disc 33 in an indexed position during periods when the lug 35 is not engaged in the space between two teeth 37. It is therefore not necessary to provide a jumper spring for indexing the hour disc 33.

Referring again to FIG. 2, it can however be seen that, in the example shown, the digital display comprises two jumper springs 41 a and 41 b respectively arranged so as to index the minute disc 31 and the disc of the minutes hours 33. Thanks to these two springs, it is indeed possible to angularly position the minutes disc 31 and the hours disc 33 with a precision better than that offered by the nesting of the cylindrical edge of the minutes disc in the rounding concave of a tooth 37 of the hour disc. It will be understood that, in the example illustrated, it is indeed the mechanism drive of the hour disc by the minute disc which ensures that the two discs do not become out of sync in the event of impacts. The jumper springs only ensure fine positioning. They do not need to be able to withstand shocks. We can therefore use jumper springs weaker than those used in the prior art.

Figure 6 is a top plan view of a digital display of the hours and minutes, which is in accordance with a second particular embodiment of the invention. By comparing FIG. 6 and FIG. 2, it can be observed that the first and the second embodiment have a large number of characteristics in common. This is the reason why the elements of the display in FIG. 6 which are identical or equivalent to the elements represented in FIG. 2 are designated in FIG. 6 by the same reference numbers increased by 100.

The display in FIG. 6 has a minute disc 131 and an hour disc 133 arranged side by side. As was already the case with the first embodiment, the hour disc bears the sequence of whole numbers from 01 to 12 which are regularly distributed along its circumference. The main difference between the display in Figure 6 and that in Figure 2 concerns the minute disc. In fact the disc 131 is provided to display the minutes from 10 to 10. To this end, the twelve numbers which it carries, regularly distributed on a peripheral ring, are constituted by two series of six multiples of 10 ordered from 00 to 50 .

The display in FIG. 6 also includes a mechanism for driving the hour disc 133 by the minute disc 131 which is similar to that of the first embodiment. However, the minute disc 131 carries two pins (or fingers) 135a, 135b which are arranged in diametrically opposite positions. As can be seen, the two pins are arranged to protrude from the periphery of the disc 131 between the last number one of the series of multiples of 10 (the number 50 in this case) and the first number of the other series of multiples of 10 (the number 00).

Referring always to FIG. 6, it can be seen that the outer edge of the minute disc 131 is formed by an annular zone 139 with a cylindrical outer profile which extends along the entire circumference of the disc 131 to the except for two interruptions at lugs 135a and 135b. These two interruptions are formed by two hollow cutouts from the bottom of which the two pins project. When one of the two pins 135a, 135b approaches the tooth 137a during the rotation of the minute disc, a portion of the annular zone 139 with a cylindrical profile gradually gives way to one of the two recesses. This change reveals a space between tooth 137a and disc 131, so that the hour disc 133 is no longer immobilized. Then, when continuing on its path, the lug 135a or 135b meets the flank of the tooth 137a, it drives it and thus rotates the hour disc 133 by one step, so that the next tooth 137 comes come to rest by bracing against another portion with a cylindrical profile of the annular zone 139. The hour disc 133 is therefore again immobilized after having exactly pivoted the angular value by one step of the toothing. It will also be understood that, according to the invention, the mechanism for driving the hour disc 133 by the minute disc 131 keeps the hour disc 133 in an indexed position during the periods when none of the pins 135a, 135b is engaged in the space between two teeth 137.

Figure 7 is a top plan view of a digital display of hours and minutes, which is in accordance with a third particular embodiment of the invention. By comparing FIG. 7 to FIG. 6, it can be observed that the second and the third embodiment have a large number of characteristics in common. This is the reason why the elements of the display represented in FIG. 7 which are identical or equivalent to elements shown in Figure 6 are designated in Figure 7 by the same reference numbers increased by 100.

Careful examination of Figure 7 shows that the main difference between the display shown in this figure and that shown in Figure 6 relates to the minute disc. In fact the disc 231 is provided to display the minutes from 15 to 15. To this end, the twelve numbers which it carries, regularly distributed on a peripheral ring, consist of three series of four multiples of 15 ordered from 00 to 45 On the other hand, the minute disc 231 carries three pins 235a, 235b and 235c which are regularly spaced around the disc. As can be seen, the three pins are arranged to project from the periphery of the disc 231 between the last number in one of the series of multiples of 15 (the number 45 in this case) and the first number of l other series of multiples of 15 (the number 00).

It will also be understood that various modifications and / or improvements obvious to a person skilled in the art can be made to the embodiment which is the subject of the present description without departing from the scope of the present invention defined by the appended claims.

Claims

1. Digital display for a timepiece comprising a first indicator disc (31; 131; 231) and a second indicator disc (33; 133; 233) each carrying a series of digits or pairs of digits regularly distributed over a peripheral ring so as to form at least one ordered sequence, the two indicator discs being arranged so as to selectively present one of the digits or pairs of digits carried by the first indicator disc (31; 131; 231) in association with one of the digits or pairs of numbers carried by the second indicator disc (33; 133; 233), the digital display further comprising a drive mechanism for the second disc by the first disc, the drive mechanism comprising a toothing which is integral with the second disc and which has a tooth (37, 37A; 137, 137A; 237, 237A) for each digit or pair of digits carried by the second disc (33; 133; 233), and at least one finger (35; 135a , 135b; 235a, 235b, 235c) integral with the first disc (31; 131; 231) and arranged to come, once per revolution of the latter, engaged with a tooth (37a, 137a, 237a) of the second disc (33; 133; 233) so as to increment the second disc by one step; characterized in that the drive mechanism is of the Maltese cross type, in that the teeth (37, 37A; 137, 137A; 237, 237A) have a truncated shape with a concave apex, and in that the digital display comprises a cam integral with the first disc (31; 131; 231) in coaxial position, the cam having a circular profile in which is formed, at the location of each of said said at least one finger (35; 135a, 135b; 235a, 235b, 235c), a hollow cut, the circular profile of the cam being complementary to the concave profile of the top of the teeth of the second disc (33; 133; 233).

2. Digital display for a timepiece according to claim 1, characterized in that the second indicator disc (33; 133; 233) and the toothing are arranged on one and the same level, said truncated teeth (37, 37A; 137, 137A; 237, 237A) projecting from the circumference of the second indicating disc, the profile of the cam and said at least one finger (35; 135a, 135b; 235a, 235b, 235c) constituting the outer edge of the first indicator disc (31; 131; 231).

3. Digital display for a timepiece according to claim 1 or 2, characterized in that the first indicator disc (31; 131; 231) has a cylindrical outer profile interrupted by a recess cut arranged at each of said at least one finger (35; 135a, 135b; 235a, 235b, 235c).

4. Digital display for a timepiece according to any one of claims 1, 2 and 3, characterized in that the series of numbers or pairs of numbers carried by the first indicator disc (31) consists of a single ordered sequence, and in that the drive mechanism comprises a single finger (35) carried by the first indicator disc (31).

5. Digital display for a timepiece according to any one of claims 1, 2 and 3, characterized in that the series of numbers or pairs of numbers carried by the first indicator disc (131) consists of two ordered sequences identical, each arranged on a peripheral half-ring and in that the drive mechanism comprises two fingers (135a, 135b) carried by the first indicator disc (131).

6. Digital display for a timepiece according to any one of claims 1, 2 and 3, characterized in that the series of numbers or pairs of numbers carried by the first indicator disc (231) consists of at least three identical ordered sequences each arranged on a sector of a peripheral ring and in that the drive mechanism comprises fingers (235a, 235b, 235c) carried by the first indicator disc (231) , the number of fingers being equal to the number of identical ordered sequences.

7. Digital display for a timepiece according to any one of the preceding claims, characterized in that it comprises two jumper springs (41 a, 41 b; 141a, 141 b; 241 a, 241 b) respectively arranged so as to index the first indicator disc (31; 131; 231) and the second indicator disc (33; 133; 233).