Musical comb for a timepiece striking mechanism

Abstract

A musical comb for a striking mechanism of a timepiece includes several tines connected to a heel for securing the comb inside the timepiece. The musical comb further includes grooves in the heel each extending into the extension of each space between the adjacent tines in order to eliminate any dissonance during actuation of the tines.

Claims

1. A musical comb suitable for a striking mechanism of a timepiece, the musical comb comprising several tines connected to a heel for securing the comb inside the timepiece, the musical comb including grooves in the heel each extending in an extension of a space between each adjacent tine, the tines being rectilinear and arranged parallel to one another in a same plane from the heel, wherein each tine is obtained by machining with a symmetry between points of connection to the heel relative to a bending plane of each tine to be actuated.

2. The musical comb according to claim 1, wherein said tines are integral with the heel to form a single one-piece part made of the same material.

3. The musical comb according to claim 1, wherein said tines are all or partly of different length from the heel to a free end so that each generates a specific note when actuated.

4. The musical comb according to claim 1, wherein each tine comprises, in proximity to a free end, a cam, which forms a ramp to allow an actuation member of the striking mechanism to actuate said tine during passage of the ramp.

5. The musical comb according to claim 4, wherein a rectilinear part of each tine, which lies behind each element on the free end side of each tine, allows frequency tuning of the musical comb to be achieved by reducing the tine length.

6. The musical comb according to claim 1, wherein the depth of each groove in the heel is identical to or greater than the thickness of each tine.

7. The musical comb according to claim 1, wherein said grooves in the heel are also made throughout the entire thickness of the heel.

8. The musical comb according to claim 1, wherein said thickness of the heel is between 2 and 10 times greater than the thickness of each tine.

9. A method for manufacturing a musical comb suitable for a timepiece striking mechanism, wherein said method comprises the steps of: providing an initial preform having the shape of a heel extended perpendicularly from one side by a flat portion of smaller thickness than the thickness of the heel, machining tines in the flat portion with an identical space between each pair of adjacent tines and a different or partly different length of each tine from the heel, and with a symmetry between points of connection to the heel relative to a bending plane of each tine to be actuated, and machining grooves in the heel each in an extension of the spaces between two adjacent tines.

10. The method for manufacturing a musical comb according to claim 9, wherein said tines are machined individually from their free end to their point of attachment to the heel.

11. The method for manufacturing a musical comb according to claim 9, wherein said spaces between each pair of adjacent tines are made by milling or by wire cutting.

12. The method for manufacturing a musical comb according to claim 9, wherein said machining of the tines from the heel to their free end is performed with a round or cylindrical milling cutter in order to obtain a symmetry between the points of connection to the heel relative to a bending plane of each tine to be actuated, and wherein each tine comprises, in proximity to a free end, a cam, the thickness of the tines and each cam at the free end of each tine is achieved by milling with a round or cylindrical cutter.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The objects, advantages and features of the musical comb for a timepiece striking mechanism, and of the method for manufacturing the musical comb will appear more clearly in the following description, particularly with reference to the drawings, in which:

(2) FIGS. 1a and 1b described above represent a three-dimensional view and a top view of an embodiment of a prior art musical comb for a striking mechanism;

(3) FIGS. 2a and 2b show a three-dimensional view and a top view of an embodiment of an optimised musical comb for a striking mechanism according to the invention; and

(4) FIGS. 3a and 3b represent a comparison between a conventional musical comb producing sound interference at each actuation of a tine and an optimised musical comb according to the invention without sound interference at each actuation of a tine.

DETAILED DESCRIPTION OF THE INVENTION

(5) In the following description, all those parts of a timepiece striking mechanism provided with at least one musical comb, which are well known in this technical field, will only be briefly described.

(6) FIGS. 2a and 2b represent an embodiment of a musical comb 1 for a musical module of a striking mechanism. Comb 1 includes a set of tines 3 which may be rectilinear. These tines 3 can be arranged parallel to one another in the same plane. The space between each tine 3 may be identical. One end of each tine is fixed to a same heel 2. Heel 2 has holes 5 for the passage of screws (not represented) in order to fix heel 2, for example, to a bridge connected to a plate, or directly to a plate or a middle part inside the case of a timepiece, such as a musical watch. Preferably, tines 3 are integral with heel 2, so as to form a single part made of the same material, i.e. a one-piece musical comb 1. The material may be, for example, a metal material, such as steel or copper, or a precious metal, such as gold or platinum, or also an amorphous structure material, such as metallic glass.

(7) To actuate tines 3 of musical comb 1, there may be provided a cam 4, which defines a ramp, at a free end of each tine 3. The ramp of cam 4 preferably forms a slope defining an acute angle relative to the free end of tine 3. An actuation member, such as a pin, can come into contact with the ramp of cam 4 so as to lift or bend the corresponding tine 3. Each actuation pin of the corresponding tine 3 may be located, for example, on a cylinder or disc of the striking mechanism. Generally, actuation of each tine by cam 4 is achieved by moving a respective pin in a plane parallel to tines 3 and in the direction of the free end of the tine 3 to be actuated. Once the actuation member, i.e. the pin, has moved beyond said cam 4, tine 3 is released so that it starts to vibrate and emits a specific note, defined in particular by its length from heel 2.

(8) A rectilinear part of the tine, which lies behind each cam 4 on the free end side of each tine 3, is required for the frequency tuning of musical comb 1. Musical comb 1 is dimensioned to have tines 3, whose fundamental frequencies remain lower than the desired frequencies that form the melody or the chime. Removing material from this end makes it possible to increase the frequency of each tine 3 and therefore to precisely tune each tine to within 5 Hz. This adjustment of the length of each tine 3 avoids any adjustment of the thickness of tine 3 in the event that the frequency of tine 3 is higher than the desired frequency. The thickness adjustment would reduce the stiffness of each tine 3. The energy stored during bending of tine 3 would be lower, as would the acoustic level.

(9) According to the invention, at the point of attachment of tines 3 to heel 2, i.e. at the place where tines 3 are joined to heel 2, grooves 6 are arranged in heel 2, extending into the extension of each space between the adjacent tines 3. Preferably, the width of each groove 6 can be identical to the space between two adjacent tines 3. Each groove 6 can be made rectilinear and along the direction of the corresponding space between two adjacent tines 3. The depth of each groove 6 may be identical to the thickness of each tine 3, or greater to avoid any vibration transfer from one tine 3 to another adjacent tine 3 during actuation of said tines. The thickness of heel 2 may be chosen to be between two and ten times greater than the thickness of each tine 3. Grooves 6 may also be made throughout the entire thickness of heel 2.

(10) This thickness of heel 2 is necessary for the conditions of each tine 3 to be defined as a clamped beam. Without this extra thickness of heel 2, i.e. if it had a similar thickness to that of tines 3 or of grooves 6, the stiffness of each tine 3 would be reduced. Thus, the assembly consisting of heel 2 and tines 3 up to the end of each groove 6 would undergo a deformation during actuation of each tine 3. The thickness of the heel also makes it possible to have a bearing surface with the plate or the external parts of the timepiece while allowing tines 3 to vibrate freely. Without heel 2, and because each tine 3 is attached at different locations according to the length of the various tines 3, some tines 3 would be in direct contact with the plate or case middle. This would prevent the actuated tine 3 from vibrating properly and would increase dampening.

(11) To make musical comb 1, it is possible to choose a preform that already includes the shape of a heel 2 extended perpendicularly from one side by a flat portion of smaller thickness where the tines are to be made. An upper surface of the flat portion is in an extension parallel to an upper surface of heel 2.

(12) Tines 3 of musical comb 1 are thus machined individually from their free end to their point of attachment to heel 2. The spaces between two adjacent tines 3 are made by a machining tool which may be, for example a milling cutter or a wire cutter. Grooves 6 in heel 2 can be obtained directly by the machining tool after each space between two adjacent tines, or at the end of the machining of musical comb 1. The thickness of each tine 3 and cam 4 of the free end of each tine 3 is adjusted by a milling operation, particularly by means of a round or cylindrical milling cutter.

(13) At the point of attachment of each tine 3 to heel 2, as shown in FIG. 2b, this type of machining produces a symmetry between points A1 and B1 relative to the bending plane of tine 3 connected to heel 2. Each line P1 connecting points A1 and B1 is perpendicular to the direction of each tine 3. Thus, the first bending mode is perfectly actuated when a pin bends tine 3 as it passes. The transmitted energy, in the first bending mode, is maximal. The vibration amplitude is also maximum, which has the effect of increasing the acoustic level of the melody and the perception of sound.

(14) It is also to be noted with regard to grooves 6 in heel 2 of musical comb 1 that they are intended to separate the tines 3 from each other and to limit vibration transfer from one tine 3 to another adjacent tine 3. Indeed, when a tine 3 is actuated, for example bent by a pin, the bending of tine 3 produces a stress at the point of attachment of tine 3 to heel 2. These grooves 6 avoid coupling between tines 3 of musical comb 1 and very precisely limit the stresses to the point of attachment of each actuated tine 3. Grooves 6 prevent a normal movement being imparted to the adjacent tines. The melody produced by musical comb 1 in this configuration of the present invention can be considered pure and free of sound interference or dissonance.

(15) For comparative purposes, FIGS. 3a and 3b represent a comparison, during actuation, for example, of the tine 3 having the highest-pitched sound, between a conventional musical comb 1 in FIG. 3a and an optimised musical comb 1 with grooves 6 according to the invention in FIG. 3b. Following bending of the highest-pitched tine 3, which is the smallest tine 3, it is noted that the actuated tine 3 vibrates after passage of the pin. The same applies to the tines 3 adjacent to the actuated tine 3 in the case of the conventional musical comb 1, which also undergo a bending motion, which is not the case of optimised musical comb 1 with grooves 6. A vibration scale from Min to Max is provided and represented on the three tines 3 of the conventional musical comb 1 and the optimised musical comb 1 without generating dissonance, since the two tines 3 adjacent to the highest-pitched actuated tine 3 normally do not vibrate.

(16) From the description that has just been given, several variants of the musical comb for a timepiece striking mechanism can be devised by those skilled in the art without departing from the scope of the invention defined by the claims. Each tine may be of rectilinear shape with a rectangular or circular or other cross-section, which may be identical over the entire length of the tine. The cross-section may also vary gradually or discontinuously along the length of each tine.