Oscillator for clockwork movement

Description

[0001] The invention relates to A oscillator of a watch movement. The invention also concerns a watch movement and a timepiece including such an oscillator.

[0002] The running accuracy of mechanical watches depends on stability of the frequency of the oscillator which is made up of a balance wheel and a hairspring. However, this frequency is disturbed if the watch is exposed to a magnetic field, so that a difference in forward and after magnetization of the movement is observed. This difference in rate can be negative or positive. Whatever its sign, this difference is called "residual effect" or "residual rate" and is measurable according to the NIHS 90-10 standard. This standard aims to certify wristwatches exhibiting good chronometric behavior following exposure to a magnetic field of 4.8 kA / m (60 G). However, the wearer of the watch may encounter in his daily magnetic fields of good intensities superior, of the order of 32 kA / m (400G). It is therefore appropriate to minimize this effect for fields of such intensities.

[0003] The vast majority of hairsprings are made from Fe- alloys.Ni (Nivarox ® alloy for example) whose elastic moduli depend of the state of magnetization. Recent developments have made it possible to develop self-compensating balance springs made from paramagnetic materials (Nb-Zr-O alloy, Parachrom ®< for example) or diamagnetic materials. (silicon covered with a layer of Si O 2 for example) which make it possible to significantly reduce the residual effect for a field magnetic greater than 4.8 kA / m, as shown in figure 1 . However, a residual effect remains, particularly for a field magnetic of a noticeably high intensity greater than 4.8 kA / m, for example 32 kA / m.

[0004] Generally speaking, the structure of a pendulum assembled within an oscillator is as represented by NIHS 34-01. The figure 3 illustrates such an assembled balance structure. The balance hub is directly attached on the balance shaft, for example by riveting. Its location and its seat are ensured by a surface support which is defined by the diameter of a the collar present on the axis, and which is also called balance seat diameter according to theterminology of the NIHS 34-01 standard. A plate, generally machined from CuBe2, on which a dowel is placed, is driven on a portion d 'axis whose diameter is significantly smaller than that of the seat of the balance wheel, independently of the balance wheel hub the other side of the collar. The collet, intended to hold the hairspring, is chased from the other side of the collar on a portion of axis whose diameter is also significantly smaller heart to that of the seat of the pendulum as illustrated in figure 2 . Such a structure of balance wheel has established itself as a benchmark given its robustness and the resulting simplicity of assembly. Such an assembled balance structure concerns in particular any oscillator equipped with a paramagnetic or diamagnetic hairspring. For example, the patent CH700032 discloses an oscillator having at least two hairsprings, for example made of silicon, which are mounted on a balance staff as described above. This oscillator, by the properties of the material chosen for the balance spring, helps reduce the residual effect in a magnetic field of the order of4.8 kA / m, but does not allow it to be minimized for a magnetic field significantly greater than 4.8 kA / m, for example 32 kA / m.

[0005] Documents FR2268291A1, CH700260A2 and EP2104007A1 disclose different structures of oscillators known from the prior art.

[0006] The goal of the invention is provide an oscillator that overcomes the drawbacks mentioned above and improves the oscillators known from the prior art. In particular, the invention provides a oscillator that minimizes, or even an null , the residual effect, negative or positive, for magnetic fields that the wearer of the watch is likely to encounter in their daily life, in particular magnetic fields higher, or even significantly higher, than 4.8 kA / m, for example 32 kA / m.

[0007] Oscillators according to the invention are defined by claims 1 to 2.

[0008] A watch movement according to the invention is defined by the claim 3.

[0009] A timepiece according to the invention is defined by the claim 4.

[0010] The attached drawings represent, as examples,two modes of production of an oscillator according to the invention. There figure 1 is a graph showing the residual step M of different motions depending on the magnetic field B to which these movements are subjected. Curve 1 illustrates the residual step M of a movement equipped with an oscillator having a magnetic balance spring (Nivarox ®< ). Curve 2 illustrates the residual rate M of a movement equipped with an oscillator having a paramagnetic hairspring (Parachrom ®< ). Finally, curve 3 illustrates the residual rate M of a movement equipped with an oscillator having a diamagnetic balance spring (Silicon covered with a layer of SiO 2 ). The figure 2 is a view of an oscillator known from the prior art. The figure 3 is a detailed view of an assembled pendulum structure of the oscillator of the figure 2 . THE figures 4 And 5 are views of a first variant of a first embodiment of an oscillator not forming part of the invention, but useful for its understanding. The figure 6 represents a second variant of a first embodiment of an oscillator not forming part of the invention, but useful for its understanding. The figure 7 represents a third th variant of afirst embodiment of an oscillator not forming part of the invention, but useful for its understanding. The figure 8 is a view of a e variant of a second embodiment of an oscillator according to the invention. The figure 9 is a view of a first variant of a third embodiment of an oscillator according to the invention. The figure 10 is a view of a second variant of a third embodiment of an oscillator according to the invention. The figure 11 is a view of a third variant of a third embodiment of an oscillator according to the invention. The figure 12 is a table showing the residual rate of a movement subjected to a given magnetic field as a function of the material of a balance shaft of a known state-of-the-art oscillator as represented in figures 2 And 3 . It also shows the residual steps d oscillators made according to the first embodiment and the second embodiment of the invention. There figure 13is a graph showing, for comparison, the residual step M of four movements as a function of the magnetic field B to which they were subjected, a first movement comprising an oscillator produced according to the first variant of the first embodiment and three movements comprising an oscillator produced according to the prior art. Curve 1 illustrates the residual step M of a movement equipped with an oscillator fitted with 'an assembled pendulum, provided with a flanged balance shaft, which is associated with a Nivarox ® hairspring. Curve 2 illustrates the residual rate M of a movement equipped with an oscillator fitted with an assembled balance wheel, provided with an axis of balance wheel without a collar, which is associated with a Nivarox ® hairspring. Curve 3 illustrates the residual rate M of a movement equipped with an oscillator fitted with an assembled balance wheel, provided with a balance staff collar, which is associated with a paramagnetic hairspring. Finally, curve 4 illustrates the residual rate M of a movement equipped with a oscillator produced according to the first variant of the first embodiment. The figure 14is a graph showing, for comparison, the residual step M of two movements as a function of the magnetic field B to which they were subjected, a first movement comprising an oscillator produced according to the first variant of the third embodiment of the invention (curve 1 of the graph) and the second movement comprising an oscillator made according to prior art Lord and endowed of an s Nivarox ® type spiral (curve 2 of the graph).

[0011] The applicant noticed that the balance shaft geometry has a surprising influence on the residual effect. More specifically, following various studies carried out by the applicant, it was noted that minimizing, or even eliminating, the portion with the largest diameter, called the balance seat according to the terminology of the NIHS 34-01 standard, or commonly called the “collar”, makes it possible to minimize the effect re side of the same way that a balance shaft is madein a paramagnetic material such as CuBe2, as shown in the table in figure 12 . We then note that associating a paramagnetic or diamagnetic hairspring with an assembled balance wheel fitted of a flanged balance shaft according to the state of the art does not produce the same effects of associating a paramagnetic hairspring or diamagnetic to a pendulum assembled fitted with a balance shaft according to the invention. More specifically, the act of associating a spinnaker paramagnetic or diamagnetic ral to an assembled balance wheel fitted with a balance shaft according to the invention allows, for a magnetic field of 32 kA / m (400G), to considerably minimize the residual step, or even to cancel it, the parasitic torque disturbing the restoring torque of the hairspring then being due to the presence of magnetic components surrounding the oscillator.

[0012] Referring to the graph of the figure 13 , we note that 'add a paramagnetic balance spring with an assembled balance wheel fitted with an a flanged balance wheel allows, for a magnetic field B of 32 kA / m (400G), to reduce the residual step M of approximately A postman2 compared to the same assembled balance wheel which is associated with a Nivarox ® type hairspring. Surprisingly, we note that associating a paramagnetic balance spring with an assembled balance wheel fitted with an axis of balance wheel without collar, as proposed in the first variant of the first embodiment, allows, for a magnetic field of 32 kA / m (400G), to reduce the residual rate of approximately a factor of 12 compared to the same assembled balance wheel which is combined with a Nivarox ® type hairspring. We also note that the oscillator of the first embodiment, allows, for a magnetic field of 32 kA / m (400G), to reduce the residual step of very significantly, by about a factor of 17, compared to an assembled balance wheel which has a flanged shaft and which is combined with a Nivarox ® type balance spring. In particular, as shown in the figure 13 , for magnetic fields between 15 and 32 kA / m, it was noticed that it happens, live -with respect to the magnetic phenomenon, a synergistic effect between the paramagnetic or diamagnetic spiral and the geometry of the axis. Indeed, the effectcombined change of matter of the spiral and the modification of the geometry of the axis goes to the -beyond the sum of the individual effects of the change in material of the hairspring and changing the geometry of the axis the effects.

[0013] Referring to the graph of the figure 14 , we notice surprisingly that combine a diamagnetic hairspring with a balance wheel assembled provided of a balance shaft whose maximum diameter is minimized, as proposed in the first variant of the third embodiment ation of the invention, allows, for a field magnetic B of 32 kA / m (400G), to reduce the residual step M of very significantly, by about a factor of 35, compared to a assembled balance wheel which has a flanged shaft and which is combined with a Nivarox ® type balance spring.

[0014] Thus, the invention relates to an oscillator comprising a hairspring inparamagnetic or diamagnetic material and a balance assembled within this oscillator comprising a steel shaft whose maximum diameter is minimized on which are mounted a balance, a plate and the collet of said balance spring. In a first case, the collet can be attached to the balance spring. In this case, it is preferably made of a copper alloy such as brass or CuBe2, or else of stainless steel. In a second case, the collet can be manufactured with the balance spring, for example when the balance spring is made of silicon. The collet is in this case also made of silicon. The tree is made of steel so as to meet mechanical constraints to which the oscillator is subjected. The plate and the balance wheel are, for their part, machined from a paramagnetic or diamagnetic material, for example a copper alloy such as CuBe2 or brass, silicon or nickel-phosphorus. The maximum diameter Dmax of the tree,the minimum diameter D1 of the shaft on which one of the elements is mounted of the oscillator and the maximum diameter D2 of the tree on which one is mounted elements of the oscillate ur are limited as defined below. Thus, the residual effect is greatly minimized because the parasitic torque disturbing the return torque of the hairspring is then mainly due to the presence of the surrounding magnetic components the oscillator. Of course, the minimization of the residual effect can be further increased by realizing the components which are located near the oscillator according to the invention, for example the escapement components such as the anchor or the escape wheel, made of paramount materials magnetic or diamagnetic.

[0015] According to a first embodiment, the smallest diameter D1 of the portion of the shaft on which an element of the oscillator is mounted (chosen from the group: collet, plate, balance wheel) has a value equal to Dmax which corresponds to the largest diameter of the shaft. Furthermore, the largest diameter D2 of the portion of the shaft on which an element is mounted of the oscillatoralso has a value which corresponds to that of the largest diameter Dmax of the shaft. Thus, in this first embodiment, Dmax=D1=D2.

[0016] According to a second embodiment of the invention, the largest diameter D2 of the portion of the axis on which is mounted an element of the oscillator also corresponds to the diameter Dmax but differs from the smallest diameter D1 of the portion of the tree on which is mounted a element of the oscillator. Thus, in this second embodiment, Dmax=D2>D1.

[0017] According to a third embodiment, the largest diameter D2 of the portion of the axis on which an element of the oscillator is mounted ur differs of the largest diameter of the axis Dmax but can be greater than or equal to the smallest diameter D1 of the portion of the tree on which it is mounted an element of the oscillator. So in this three th embodiment, Dmax>D2≥D1

[0018] A first variation of the first oscillator embodiment is described below with reference to the figures 4 And 5 . Oscillator 10comprises a balance spring 11 made of paramagnetic or diamagnetic material and an assembled balance wheel 12 comprising a shaft 13 on which are mounted a balance wheel 14, a plate 15 and the collet 16 of said balance spring. In this first variant, the balance wheel 14 is secured to the shaft 13 by through the plate 15. The latter is reported, for example by chasing, on a portion 135 and tree shirt 13 on a height H. The diameter of this portion 135 is equal to the maximum diameter Dmax. The balance 14 is, for its part, attached to the plate 14, for example by riveting, on a surface seat face 131 made on the plate. The ferrule is, for its part, directly mounted on the shaft. It can be fixed there, for example, by driving. The ferrule is mounted on a portion 136 of the shaft whose diameter is equal to the maximum diameter Dmax of the shaft. In this first variant of the first embodiment, the smallest diameter D1 of the portion of the shaft on which an element is mounted(chosen from the group: collet, plate, balance) corresponds to the value Dmax which is equal to the largest diameter of the shaft. Furthermore, the largest diameter D2 of the portion of the shaft on which an element is mounted also has a value which coincides with that of the largest diameter of the shaft. Thus, in this first variant of the first embodiment, Dmax=D1=D2. In this first variant of the first embodiment (illustrated by the figures 4 And 5 ), this value is of the order of 0.5 mm.

[0019] Measurements were made for magnetic fields at different intensity levels in order to compare the residual step of the first variant of the first embodiment of the oscillator and those of oscillators known from the prior art. It can be seen, as shown in the figure 13 , that the average residual step of a movement with the first variant of the first embodiment of the oscillator, for a magnetic field of 32 kA / m, is of the order of 2 s / d(curve 4 of the graph), or a decrease of approx. ron a factor of 12 compared to that of a movement equipped with an oscillator known to have a Nivarox ® hairspring and a balance staff without collar (curve 2 of the graph). We also note that the step average residual of a movement equipped with an oscillator equipped with a pendulum assembled, provided with a flanged balance shaft, which is associated with a paramagnetic spiral, for a magnetic field of 32 kA / m, is of the order of 15 s / d (curve 3 of the graph), i.e. a decrease of about a factor of 2 compared to that of a movement equipped with the same assembled balance wheel which is associated with a Nivarox ® hairspring. Thus, we see that combining a paramagnetic hairspring with a balance wheel assembled with a shaft without collar produces an unexpected effect on the residual step of a movement ent, namely, its clear minimization, or even its cancellation, for a magnetic field of 32kA / m (400G).

[0020] Furthermore, this factor is likely to increase by minimizing the number of surrounding magnetic components the bone ciller within the movement considered.

[0021] A second variation of the first oscillator embodiment is described below with reference to the figure 6 . In this second variant, the elements that are identical or have the same function as the elements of the first variant have a "2" in the tens digit instead of the "1" and have the same units digit. The parts or portions of these elements also have a "2" in the hundreds digit instead of the "1" of the equivalent parts or portions of the elements of the first variant and have the same tens digit. Just as in the first variant of the first embodiment, Dmax=D1=D2. In this second variant of the first embodiment (illustrated by the figure 6 ), this will theirs is from 'order of 0.3 mm. This second variant differs from the first variant in that the plate 25 covers the shaft over practically its entire length and / or in that the ferrule 26 is fixed to the shaft via the plate. In other words, the ferrule 26 is fixed, for example by driving, onto the plate 25.

[0022] Measurements show that this change has very little impact on minimizing the effect residual. Whatever the variant considered, the average residual step, for a magnetic field of 32 kA / m, is 2 s / d, a reduction of a factor of 8 compared to that of a movement with a known state-of-the-art design as illustrated in figures 2 And 3 and equipped with a paramagnetic hairspring.

[0023] According to the first two variants of the first embodiment, the balance is attached to the tree via the tray. By compared to the usual structure known from the prior art, the collar of the shaft is thus eliminated and the whole tray - pendulum can be directly reported on the tree, for example by driving. Alternatively, according to a third variant of the first embodiment, the balance is directly attached to a portion of the tree whose dia meter is equal to those of the portions on which the plate and the collet are attached. Thus, the balance can be reported on the tree regardless of the plateau.

[0024] In this third variant of the first embodiment illustrated by the figure 7, the elements identical or having the same function as the elements of the first variant of the first embodiment have a “3” in the first digit (tens or hundreds) instead of the “1” and have the same second digit (units or tens). The balance 34 is fixed on a portion 334 independently of the plate 35 which is attached to a portion 335. To do this, the hub of the balance 34 has a sufficient total height H, in particular equal or substantially equal to the height of the portion 334, so as to guarantee adequate seating and holding torque of the balance. The collet is, for its part, fixed on a portion 336, for example by driving. The diameter of each of the portions 334, 335, 336 is equal to the maximum diameter Dmax of the shaft. Thus, just as in the first two variants, Dmax=D1=D2. In this third variant of the first embodiment (illustrated by the figure 7 ), this value is of the order of 0.4 mm. The measurements show that the average residual step of a soft equipped with an oscillator made according to this third variant, for a magnetic field of 32kA / m, is equivalent to that of a movement equipped with an oscillator made according to one or other of the two first variants, namely approximately 2 s / d.

[0025] The second embodiment differs from the first embodiment in that the value of the largest diameter of the shaft Dmax does not coincide with that of the minimum diameter D1 of the shaft on which one of the elements chosen from the group is mounted ferrule, plate, balance wheel. In in other words, Dmax=D2>D1. A variant of the second oscillator embodiment is described below with reference to the figure 8 .

[0026] In this second embodiment, the elements identical or having the same function as the elements of the first variant of the first embodiment have a “4” in the first digit (tens or hundreds) instead of the “1” and have the same second digit (units or tens). In this embodiment, the ferrule 46 is attached to tree 43 at a portion 436, for example by driving. The plate 45 is, for example, driven into abutment on a portion 435. The diameter of this portion is equal to the minimum diameter D1 of the axis on which it is mounted an element. The balance wheel 44 is, for its part, directly mounted on tree 43 at the level of a portion 434, for example by driving, independently of the location of the plate 45. To do this, the hub of the balance wheel 44 has a sufficient total height H, in particular equal or substantially equal to the height of the portion 434, so as to guarantee adequate seating and holding torque of the balance wheel. The diameter of this portion 434 is equal to the diameter maximum D2 of the axis on which is mounted an element. It also corresponds to the diameter Dmax. In this embodiment, illustrated by the figure 8 , D1 is of the order of 0.4 mm, D2 and therefore Dmax are of the order of 0.8 mm. Thus, Dmax is less than about 2.5 times the diameter D1.

[0027] Measurements were carried out for a magnetic field of 32 kA / m in order to compare the residual step of this variant of the second embodiment of the oscillator and that of an oscillator known from the prior art as illustrated in figures 2 And 3, both being equipped with a sp paramagnetic iral. The table of the figure 12 shows that the average residual step, for a magnetic field of this intensity, is of the order e of 2 s / d, a decrease of approximately a factor of 8 compared to that of a movement with a known oscillator and endowed of a paramagnetic or diamagnetic hairspring.

[0028] The third embodiment differs from the second embodiment in that the value of the largest diameter of the shaft Dmax does not coincide not with that of the maximum diameter D2 of the shaft on which one of the elements chosen from the collet, plate, balance group is mounted. Thus, Dmax>D2≥D1.

[0029] A first variant of the third mo of the embodiment of an oscillator according to the invention is described hereinafter with reference to the figure 9 . In this first variant of the third embodiment, the elements identical or having the same function as the elements of the first variant of the first embodiment have a “5” in the first digit (tens or hundreds) instead of the “1” and have the same second digit (units or tens). The ferrule 56 is directly mounted on the shaft 53 at the level of a portion536, for example by driving. The plate 55 is also directly mounted on the shaft 53. It is, for example, driven into abutment on the shaft 53 at a portion 535. The diameter of this portion is equal to the minimum diameter D1 of the axis on which is mounted an element. The balance wheel is reported on the tree at the level of a portion 534, for example by driving. To do this, the hub of the balance 54 has a sufficient total height H, in particular equal or substantially equal to the height of the portion 534, so as to guarantee adequate seating and holding torque of the balance. The diameter of this portion 534 is equal to the diameter maximum D2 of the axis on which an element is mounted. In this first variant of the third embodiment, a portion tree533 has a diameter Dmax greater than the diameters D1 and D2. Thus, this portion has shoulders against which the balance and / or the collet are likely to come to rest when they are fixed on the shaft. In this way, the position of the balance and that of the collet can be precisely defined.

[0030] In this first variant of the third embodiment, illustrated by the figure 9 , D1 is of the order of 0.3 mm, D2 is of the order of 0.8 mm, and Dmax is of the order of 1 mm. Thus, Dmax is less than about 3.5 times the diameter D1, and Dmax is less than about 1.3 times the diameter D2. Within a known state-of-the-art design such as represented at figures 2 And 3 within which Dmax>D2>D1, D1 is of the order of 0.3 mm, D2 is of the order of 0.8, and Dmax is of the order of 1.4 mm. Dmax is then greater than 4.5 times the diameter D1, and Dmax is then greater than 1.6 times the diameter D2. We therefore see that the largest shaft diameter Dmax is greatly minimized with respect to the largest diameter Dmax of a shaft equipping an oscillator known from the state of the art. Thus, the residual effect is minimized because the parasitic torque disturbing the return torque of the hairspring is then mainly due to the presence of the magnetic components surrounding the oscillator. There figure 14 shows the residual march of the first variant of the third mode of realization sation of the o scillator in comparison to that of an oscillator known which includes a flanged balance shaft and which is provided with a Nivarox ® type hairspring. We note that the average residual step, for a magnetic field of 32kA / m is from the o order of 1 s / day, a very significant reduction by a factor of 35 compared to that of a movement equipped with the oscillator aforementioned.

[0031] A second variant of the third embodiment oscillator according to the invention is described hereinafter with reference to the figure 10. In this second variant of the third embodiment, the elements identical or having the same function as the elements of the first variant of the first embodiment have a “6” in the first digit (tens or hundreds) instead of the “1” and have the same second digit (units or tens). Just as in the first variant of the third embodiment, Dmax>D2>D1. This second variant differs from the first variant in that the balance 64 e is attached to the shaft 63 via the plate 65. The latter is reported, for example by chasing, on a portion 635 and shirt the shaft 63 on a height H1. The diameter of this portion 635 is equal at the minimum diameter D1 of the shaft on the which is mounted an element of the oscillator.The balance wheel is mounted in abutment on the plate, for example by driving it in. To do this, the hub of the balance wheel 64 has a sufficient total height H2, in particular equal or substantially equal to the height of the portion 654 of the plate 65, so as to guarantee adequate seating and holding torque for the balance wheel. The collet is, for its part, fixed on a portion 636 of the shaft 63, for example the by chasing. The diameter of this portion 635 is equal to the diameter e maximum D2 of the shaft on which an element of the oscillator is mounted. In this second variant of the third embodiment, a portion of a tree 633 has a diameter Dmax greater than the diameters D1 and D2. Thus, this portion has shoulders against which the plate and / or the collet are likely to come to bear when they are fixed on the shaft. In this way, the position of the balance wheel and that of the collet can be precisely defined. In this second variant of the third embodiment illustrated by the figure 10 , D1 is of the order of 0.4 mm, D2 is of the order of 0.5 mm, and Dmax is of the order of 0.7mm. Thus, Dmax is less than about 2 times the diameter D1, and Dmax is less than about 1.6 times the diameter D2. In this way, the largest diameter Dmax of the tree is also greatly minimized.

[0032] A third variant of the third embodiment differs from the first two variants in that the value of the maximum diameter D2 of the shaft on which an element of the oscillator is mounted is equal to that of the minimum diameter D1 on which an element of the oscillator. This variant is described below with reference to the figure 11 . Elements identical or having the same function as the elements of the first variant of the first embodiment have a “7” in the first digit (tens or hundreds) instead of the “1” and have the same second digit (units or tens). Just as in the second variant of the third embodiment, the balance 74 is attached to the shaft 73 via the plate 75. The latter is reported, for example by driving, on a portion 735 and sleeves the shaft 73 on a height H1. The diameter of this portion 735 is equal to the minimum diameter D1 of the shaft on which an element of the oscillator is mounted.The diameter of this portion 735 also corresponds to the maximum diameter D2 of the tree on which is mounted an element of the oscillator. The balance wheel is mounted in abutment on the plate, for example by driving it in. To do this, the hub of the balance wheel 74 has a sufficient total height H2, in particular equal or substantially equal to the height of the portion 754 of the plate 75, so as to guarantee adequate seating and holding torque for the balance wheel. The collet is, for its part, fixed on a portion 736 of the tree 73, for example by chasing. The diameter of this portion 736 corresponds to the maximum diameter D2 of the shaft on which an element of the oscillator is mounted, and also corresponds to the minimum diameter D1 of the shaft on which an element of the oscillator is mounted. So, D1=D2. In this third variant, a portion tree733 has a diameter Dmax greater than the diameters D1 and D2. Thus, this portion has shoulders against which the plate and / or the collet are likely to come to bear when they are fixed on the shaft. In this way, the position of the balance wheel and that of the collet can be precisely defined. In this third variant, illustrated by the figure 11 , D1 and D2 are the order of 0.4 mm, and Dmax is of the order of 0.7 mm. Thus, Dmax is less than approximately 2 times the diameter D1, and Dmax is less than about 2 times the diameter D2. in this way the largest diameter Dmax of the shaft is also greatly minimized.

[0033] In the third embodiment, Dmax is preferably the diameter of a seat in contact with which one can chase a element, or even two elements (plate, balance wheel, collet), on the axle.

[0034] Whatever the embodiment, when a first element, for example the balance, is not mounted directly on the shaft but is mounted on a second element, itself mounted directly on the shaft at a first portion of the shaft having a first diameter, it is considered that the diameter of the shaft on which the first element is mounted is the first diameter.

[0035] The oscillator according to the invention provided with a spiral paramagnetic (Nb-Zr-O alloy, Parachrom ®< for example) or diamagnetic (notably silicon covered with a layer of SiO2) has the specificity of being equipped with a balance shaft made of free-cutting steel whose geometry has been modified so as to minimize the residual effect. The plate and the balance wheel are, for their part, machined from a paramagnetic or diamagnetic material, for example a copper alloy such as CuBe2 or brass, silicon or nickel-phosphorus. The plate, depending on the embodiment considered, is preferably adapted so as to allow assembly of the pendulum.

[0036] In this document, by " a first element attached to a second element”, we mean that the first element is attached to the second element.

[0037] In this document, "assembled balance wheel" means an assembly comprising or consisting of 'a balance shaft, a balance wheel, a plate and a collet, the balance wheel, the plate and the collet being mounted on the axis of pendulum.

[0038] In this document, "axis" and "shaft" refer to the same element.

[0039] In this document, the ratios of the values ​​of the residual steps are given in absolute value.

[0040] The graphics of the figures 1 , 13 And 14 are made to scale, so well that values, in particular residual walking values, can be deduced from it by measurement on the graph.

Claims

1. An oscillator (10; 20; 30; 40; 50; 60; 70) comprising a balance spring (11; 21; 31; 41; 51; 61; 71) made of a paramagnetic or diamagnetic material and an assembled balance (12; 22; 32; 42; 52; 62; 72) comprising a shaft (13; 23; 33; 43; 53; 63; 73) made of steel and on which the following elements are mounted: a balance (14; 24; 34; 44; 54; 64; 74), a roller (15; 25; 35; 45; 55; 65; 75) and a collet (16; 26; 36; 46; 56; 66; 76) secured to said balance spring (11; 21; 31; 41; 51; 61; 71), characterized in that: - the maximum diameter (Dmax) of the shaft is about 0.8 mm and the maximum diameter (D2) of the shaft on which one of the elements is mounted and on which the balance is mounted is about 0.8 mm and the minimum diameter (D1) of the shaft on which one of the elements is mounted and on which the roller is mounted is about 0.4 mm, or - the maximum diameter (Dmax) of the shaft is about 1 mm and the maximum diameter (D2) of the shaft on which one of the elements is mounted and on which the balance is mounted is about 0.8 mm and the minimum diameter (D1) of the shaft on which one of the elements is mounted and on which the roller is mounted is about 0.3 mm, or - the maximum diameter (Dmax) of the shaft is about 0.7 mm and the maximum diameter (D2) of the shaft on which one of the elements is mounted and on which the collet is mounted is about 0.5 mm and the minimum diameter (D1) of the shaft on which one of the elements is mounted and on which the roller is mounted is about 0.4 mm, or - the maximum diameter (Dmax) of the shaft is about 0.7 mm and the maximum diameter (D2) of the shaft on which one of the elements is mounted and on which the collet is mounted is about 0.4 mm and the minimum diameter (D1) of the shaft on which one of the elements is mounted and on which the roller is mounted is about 0.4 mm.

2. The oscillator as claimed in the preceding claim, characterized in that the balance shaft is made of profile turning steel.

3. A clock movement comprising an oscillator (10; 20; 30; 40; 50; 60; 70) as claimed in one of the preceding claims.

4. A timepiece comprising a clock movement as claimed in the preceding claim or an oscillator (10; 20; 30; 40; 50; 60; 70) as claimed in one of claims 1 to 2.