Beard ball

Abstract

To provide a collet capable of eliminating or reducing the correction work of a balance spring after installing (fixing) the balance spring.SOLUTION: A collet 60 includes: a through hole 63 formed in the center to which a balance shaft 20 is fixed; and a groove 61 into which an inner peripheral end portion 41a is inserted, and which is formed near the outer edge in the circumferential direction of the inner peripheral end portion 41a of a balance spring 40 attached. An outer wall portion 62 in the radial direction, which divides the groove 61 and has a central axis C at the center is deformable towards an inner wall portion 69 in the radial direction. The inner peripheral end portion 41a of the balance spring 40 inserted into the groove 61 is temporarily fixed by being sandwiched between the inner wall portion 69 and the outer wall portion 62 by the outer wall portion 62 deformed.SELECTED DRAWING: Figure 5A

Description

Technical Field

[0001] The present invention relates to a collet.

Background Art

[0002] A balance in a mechanical timepiece comprises: a balance wheel having an annularly formed portion and an arm bridging to the annular center; a balance staff arranged at the center of the balance wheel; a spirally formed hairspring; the collet for fixing one end portion on the inner peripheral side of the hairspring to the balance staff; and a stud for fixing one end portion on the outer peripheral side of the hairspring to an immovable portion such as a balance cock.

[0003] Herein, there has been proposed a configuration in which the hairspring is fixed to the collet by welding the hairspring to a side surface of the collet (see, for example, Patent Document 1).

Prior Art Literature

Patent Literature

[0004]

Patent Document 1

Summary of Invention

Problem to be Solved by the Invention

[0005] However, in a configuration where the hairspring is joined to the side surface of the collet by welding, core misalignment is likely to occur when the hairspring contracts due to thermal deformation during welding. For this reason, it is necessary to correct the shape of the hairspring after welding, and this correction work is labor-intensive.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a collet that eliminates the need for a work of correcting the hairspring after the hairspring is attached (fixed), or can reduce the occurrence of the work of correcting the hairspring.

Means for Solving the Problem

[0007] The present invention relates to a hairspring ball comprising a through hole formed in the center for fixing a balance staff, and a groove formed near the outer edge along the circumferential direction of the inner end of a hairspring to be attached, into which the inner end is inserted, wherein the radial outer wall portion that partitions the groove, centered on the central portion, is deformable toward the radial inner wall portion, and the deformation of the outer wall portion temporarily fixes the inner end of the hairspring inserted into the groove by sandwiching it between the inner wall portion and the outer wall portion. [Effects of the Invention]

[0008] The hairspring ball according to the present invention eliminates the need for adjusting the hairspring after it has been attached (fixed), or reduces the occurrence of such adjustment work. [Brief explanation of the drawing]

[0009] [Figure 1] This is a plan view showing the balance wheel in the regulating mechanism of a mechanical watch. [Figure 2] This is a cross-sectional view showing a section along line AA in Figure 1. [Figure 3] This is a magnified view of section B in Figure 2. [Figure 4] This is a plan view showing the hairspring, hairspring holder, and hairspring bud joined together. [Figure 5A] This is a perspective view of the whisker ball, with its top surface facing upwards, similar to the arrangement of the whisker holder. [Figure 5B] This is a perspective view of the whisker ball, with the lower surface, furthest from the whisker holder, facing upwards. [Figure 6] This is a plan view of the top surface along the thickness direction T of the whisker ball. [Figure 7] This is a cross-sectional view showing the cross-section along the DD line in Figures 5A and 6. [Figure 8] This is a schematic diagram showing the state after the inner circumference end of the hairspring is inserted into the groove and temporarily fixed, and then finally fixed (permanently fixed) by welding P. [Figure 9]This figure, corresponding to Figure 8, shows the details of the groove of the whisker ball as a modified example 1 of the embodiment. [Figure 10] This figure, corresponding to Figure 8, shows the details of the groove of the whisker ball as a modified example 2 of the whisker ball of the embodiment. [Figure 11] This diagram (part 1) schematically shows an example of the manufacturing process (manufacturing method) when producing whisker balls using the electroforming process, in a cross-section along the DD line in Figures 5A and 6. [Figure 12] This is a schematic diagram (part 2) showing an example of the manufacturing process (manufacturing method) when producing whisker balls using the electroforming process, in a cross-section along the DD line in Figures 5A and 6. [Figure 13] This is a schematic diagram (part 3) showing an example of the manufacturing process (manufacturing method) when producing whisker balls using the electroforming process, in a cross-section along the DD line in Figures 5A and 6. [Modes for carrying out the invention]

[0010] An embodiment of the hairspring ball according to the present invention will be described below with reference to the drawings. Figure 1 is a plan view showing the balance wheel 100 in the regulating mechanism of a mechanical watch, Figure 2 is a cross-sectional view showing a cross section along line AA in Figure 1, Figure 3 is a magnified view of part B in Figure 2, and Figure 4 is a plan view showing the state in which the hairspring 40, hairspring holder 50, and hairspring ball 60 are joined together. The hairspring ball 60 in the illustrated balance wheel 100 is one embodiment of the hairspring ball according to the present invention.

[0011] <Template composition> The balance wheel 100 shown in the illustration comprises a balance wheel 10, a balance staff 20, a balance seat 30, a hairspring 40, a hairspring holder 50, and a hairspring ball 60.

[0012] The celestial wheel 10 is formed in an annular shape. The celestial wheel 10 has a plurality of arms 15 that bridge the annular portion and the central part of the annular shape. The celestial staff 20 is press-fitted into the arms 15 and the swing seat 30 at the center of the celestial wheel 10, and is rotatable together with the celestial wheel 10 and the swing seat 30 around the central axis C of the celestial wheel 10.

[0013] As shown in FIG. 4, the hairspring 40 has a contour shape wound in a spiral shape according to an Archimedes curve (Archimedean spiral). An inner peripheral end (inner end) 41a of the spiral of the hairspring 40 is joined and attached (fixed) to a collet 60 described later. An outer peripheral end (outer end) 42 of the spiral of the hairspring 40 is joined to a balance spring stud 50 described later. As shown in FIG. 2, the balance spring stud 50 is fixed to an immovable portion such as a bridge at a position biased upward relative to the spiral surface of the hairspring 40.

[0014] The inner peripheral end 41a of the hairspring 40 joined to the collet 60 refers to a portion near the inner peripheral edge 41, and the inner peripheral end 41a may include the inner peripheral edge 41. That is, the inner peripheral end 41a is not limited to the narrow meaning indicating only the inner peripheral edge 41, but includes a portion near the inner peripheral edge 41. Therefore, the inner peripheral end 41a may or may not include the inner peripheral edge 41. In the collet 60 of the present embodiment, as shown in FIG. 4, the inner peripheral end 41a does not include the inner peripheral edge 41. In the collet 60 of the present embodiment, similar to the inner peripheral end 41a, the outer peripheral end 42 may or may not include the outer peripheral edge. In the collet 60 of the present embodiment, the outer peripheral end 42 includes the outer peripheral edge.

[0015] <Configuration of Collet> FIGS. 5A and 5B are perspective views showing the collet 60. FIG. 5A is a perspective view of the collet 60 in a posture where an upper surface 60a close to the arrangement of the balance spring stud 50 faces upward, and FIG. 5B is a perspective view of the collet 60 in a posture where a lower surface 60b far from the arrangement of the balance spring stud 50 faces upward. In FIGS. 5A and 5B, the direction orthogonal to both the upper surface 60a and the lower surface 60b is the thickness direction T of the collet 60.

[0016] Figure 6 is a plan view of the top surface 60a of the hairspring 60 along the thickness direction T, Figure 7 is a cross-sectional view showing the cross-section along the DD line in Figures 5A and 6, and Figure 8 is a schematic diagram showing the state in which the inner circumference end 41a of the hairspring 40 is inserted into the groove 61 and temporarily fixed, and then final fixing (permanent fixing) is performed by welding P.

[0017] The whisker head 60 is formed of, for example, nickel. However, the whisker head 60 is not limited to nickel; it may be formed of a material other than nickel, as long as the outer wall portion 62 of the groove 61 (described later) is deformable toward the inner wall portion 69.

[0018] Furthermore, it is preferable that the whisker ball 60 is manufactured by the LIGA (Lithographie, Galvanoformung, Abformung) method, which includes a novel process described later, and therefore it is preferable that the material be one that can be manufactured by this LIGA method.

[0019] The LIGA method is a manufacturing method in which a resist is formed on a conductive substrate, and a pattern of soluble and insoluble areas is formed on the resist to create an electroforming mold corresponding to the pattern. Products (electroformed products) are then manufactured by electroplating using this electroforming mold. Because it can produce fine and high-precision products, it is suitable for manufacturing watch parts.

[0020] In a plan view, the whisker ball 60 has a through hole 63 formed in the center containing the central axis C. The through hole 63 is a hole into which the balance staff 20 is fixed. As shown in Figures 5A and 5B, the introduction hole 63b and the fitting portion 63a of the through hole 63 are provided adjacent to each other along the thickness direction T, coaxially with a common central axis C.

[0021] As shown in Figure 3, the entry hole 63b is formed with an inner diameter larger than the outer diameter of the balance staff 20, so that when the balance staff 20 is inserted into the through hole 63, the balance staff 20 is inserted before the fitting portion 63a. On the other hand, the fitting portion 63a is through which the balance staff 20 inserted from the entry hole 63b passes, fits the balance staff 20, and fixes the balance staff 20 to the whisker 60.

[0022] As shown in Figures 5A and 5B, the fitting portion 63a is formed by a plurality of protruding portions 64 that extend radially inward from the circumferential surface having the same inner diameter as the introduction hole 63b. In this embodiment, seven protruding portions 64 are formed along the circumferential direction around the central axis C at approximately equal angular intervals. Note that when the fitting portion 63a is formed by a plurality of protruding portions 64 that extend radially inward from the circumferential surface, the number of protruding portions 64 may be three or more, and is not limited to seven.

[0023] The fitting portion 63a is not limited to being formed by the multiple protruding portions 64 described above, but may simply be formed as a hole whose inner diameter is smaller than the outer diameter of the balance staff 20 and which protrudes radially inward more uniformly than the introduction hole 63b in the circumferential direction. However, a fitting portion 63a formed by multiple protruding portions 64 can reduce the weight of the hairspring 60 and reduce the moment of inertia of the hairspring 60 around the central axis C compared to a fitting portion 63a formed by a hole with a smaller inner diameter.

[0024] As shown in Figure 6, the fitting portion 63a has a virtual line Ce drawn by smoothly connecting the radially inwardly protruding tip surfaces 64a of the seven protruding portions 64, which forms a circle with a radius from the central axis C. The inner diameter of this circle formed by the virtual line Ce is smaller than the outer diameter of the balance staff 20. As a result, the balance staff 20 is fitted into the tip surfaces 64a of the fitting portion 63a and fixed to the hairspring 60.

[0025] Although the introduction hole 63b and the fitting portion 63a are provided adjacent to each other along the thickness direction T, as shown in Figure 7, the introduction hole 63b is formed in a second thickness region 60d along the thickness direction T of the hairspring 60, where a bottom wall 68 that partitions the groove 61 is formed, and the fitting portion 63a, which protrudes radially inward from the introduction hole 63b, is formed in a first thickness region 60c where an inner wall portion 69 and an outer wall portion 62 that partition the groove 61 to which the hairspring 40 is fixed are formed.

[0026] As shown in Figures 5A and 5B, the whisker ball 60 has three protrusions 60A, 60B, and 60C that project radially outward from the central axis C at three locations around the through hole 63, and these three protrusions 60A, 60B, and 60C form a roughly triangular shape in plan view.

[0027] Three protrusions 60A, 60B, and 60C each have weight-reducing holes 65, 66, and 67 that penetrate in the thickness direction T. The weight-reducing holes 65, 66, and 67 reduce the weight of the hairspring 60, thereby lowering the moment of inertia of the hairspring 60 around its central axis C, and also function to adjust the rotational balance around the central axis C when the hairspring 40 is fixed to the hairspring 60.

[0028] A groove 61 is formed in one of the protrusions 60C of the hairspring ball 60, radially outward from the through hole 63 and near the outer edge of the protrusion 60C. The inner circumferential end portion 41a (see Figure 4) of the hairspring 40 attached to the hairspring ball 60 is inserted into this groove 61. The significance of the inner circumferential end portion 41a is as described above, and in this embodiment, the inner circumferential end edge 41 of the hairspring 40 is not inserted into the groove 61, but the inner circumferential end edge 41 of the hairspring 40 may be inserted into the groove 61.

[0029] As shown in Figure 7, the groove 61 is formed by being partitioned by an outer wall portion 62 in the radial direction from the central axis C, an inner wall portion 69 in the radial direction, and a bottom wall 68 on the lower side in the thickness direction T. The inner wall portion 69 is formed with a contour shape along the circumferential direction of the inner circumferential end portion 41a of the hairspring 40. As the hairspring 40 is formed with an Archimedean curve contour shape as described above, the inner wall portion 69 is formed with an Archimedean curve contour shape.

[0030] The outer wall portion 62 of the groove 61 is formed to be deformable toward the inner wall portion 69. The width of the groove 61, defined by the distance between the outer wall portion 62 and the inner wall portion 69, is formed to be slightly larger than the thickness of the hairspring 40 (for example, 3 to 5 μm larger than the groove width).

[0031] The inner wall portion 69 and the outer wall portion 62 that partition the groove 61 are formed in the first thickness region 60c, which is on the upper surface 60a side of the whisker ball 60 in the thickness direction T of the whisker ball 60, as shown in Figure 7. On the other hand, the bottom wall 68 that partitions the groove 61 is formed in the second thickness region 60d, which is on the lower surface 60b side of the whisker ball 60 in the thickness direction T of the whisker ball 60.

[0032] In other words, the whisker ball 60 has a groove 61 and a fitting portion 63a formed in the same thickness region (first thickness region 60c) in the thickness direction T, and a bottom wall 68 and an introduction hole 63b formed in the same thickness region (second thickness region 60d) in the thickness direction T.

[0033] Then, with the inner circumferential end portion 41a of the hairspring 40 inserted into the groove 61, as shown in Figure 8, the outer wall portion 62 is pressed toward the inner wall portion 69 and plastically deformed, thereby sandwiching the inner circumferential end portion 41a of the hairspring 40 between the inner wall portion 69 and the outer wall portion 62, and fixing (temporarily fixing) the hairspring 40 to the hairspring ball 60 with a certain degree of strength so that it does not move.

[0034] The inner circumference end 41a of the temporarily fixed hairspring 40 follows the inner wall portion 69, thus maintaining the shape of the inner circumference end 41a of the hairspring 40 in the form of an Archimedes curve.

[0035] As shown in Figure 8, the hairspring 40 can be temporarily fixed to the hairspring 60 by welding P to the hairspring 40, with the inner circumferential end portion 41a of the hairspring 40 temporarily fixed to the groove 61, and then joining the hairspring 40 to the outer wall portion 62 and the inner wall portion 69.

[0036] In this embodiment, the hairspring 40 is temporarily fixed to the hairspring 60, preventing it from moving. However, in conventional hairsprings where the hairspring 40 is not temporarily fixed, when the hairspring 40 is joined to the hairspring by welding P, the position in which the hairspring 40 is fixed or the fixed posture of the hairspring 40 is prone to shifting due to the heat of welding. To suppress the effect of shifts in the fixed position or posture on the rate, it was essential to modify the shape of the hairspring after fixing.

[0037] In contrast, the hairspring 60 of this embodiment can be joined by welding P while the hairspring 40 is temporarily fixed, thus preventing displacement of the hairspring 40's fixed position or fixed posture due to the heat of welding. Therefore, the hairspring 60, in the assembled state joined to the hairspring 40, can maintain the inner circumference end 41a of the hairspring 40 in the shape of an Archimedes curve.

[0038] Therefore, the hairspring 40 of this embodiment does not require any modification work after the hairspring 40 is fixed, which reduces the manufacturing cost of the assembly consisting of the hairspring ball 60 and the hairspring 40, and also reduces the manufacturing cost of the watch equipped with the balance wheel 100 in this embodiment.

[0039] Furthermore, in this embodiment, since the fitting portion 63a and the groove 61 of the hairspring 60 are formed in the same thickness region (first thickness region 60c) in the thickness direction T of the hairspring 60, the balance staff 20 fixed by the fitting portion 63a and the hairspring 40 fixed by the groove 61 can be arranged on the same plane in the thickness direction T.

[0040] As a result, the hairspring 60 can fix the pivot point of the hairspring 40 to the balance staff 20 within the plane of the hairspring 40, and the oscillation of the hairspring 40 can be stabilized compared to when the pivot point of the hairspring 40 is fixed to the balance staff 20 outside the plane of the hairspring 40 (at a position off-center in the thickness direction T from the plane of the hairspring 40).

[0041] <Example 1> FIG. 9 is a view corresponding to FIG. 8, showing details of the groove 61 of a balance spring stud 160 serving as a first modification of the balance spring stud 60 of the above-described embodiment. The illustrated balance spring stud 160 differs from the balance spring stud 60 only in that a taper 62b is formed on the outer wall 62 at the end 61b of the groove 61 such that the groove width w2 at the end 61b on the side far from the inner peripheral edge 41 (see FIG. 4) of the balance spring 40 in a state where the balance spring 40 is attached to the balance spring stud 160 is wider than the groove width w1 at the end 61c on the side close to the inner peripheral edge 41 of the balance spring 40 (w1 < w2), and is otherwise the same as the balance spring stud 60.

[0042] The balance spring stud 160 of the first modification configured as described above exhibits the same functions and effects as the balance spring stud 60. In addition, when inserting the inner peripheral edge 41 of the balance spring 40 into the groove 61 from the one end 61b, the balance spring stud 160 enables easier insertion compared to the case of inserting from the other end 61c having a relatively narrow groove width w1.

[0043] <Modification 2> FIG. 10 is a view corresponding to FIG. 8, showing details of the groove 61 of a balance spring stud 260 serving as a second modification of the balance spring stud 60 of the above-described embodiment. The illustrated balance spring stud 260 differs from the balance spring stud 60 only in that, for the groove 61, the groove width in the range from one end 61b to an intermediate position is a groove width w1 slightly wider than the thickness t1 of the balance spring 40 (w1 > t1), while the groove width in the range from the intermediate position toward the other end 61c is formed as a groove width w3 narrower than the thickness t1 of the balance spring 40 (w3 < t1), and is otherwise the same as the balance spring stud 60.

[0044] The balance spring stud 260 of the second modification configured as described above exhibits the same functions and effects as the balance spring stud 60. Further, when the inner peripheral edge 41 of the balance spring 40 is inserted into the groove 61 from the one end 61b, the balance spring 40 is inserted into the groove 61 until the inner peripheral edge 41 reaches the intermediate position; when the inner peripheral edge 41 reaches the position of the groove width w3, the inner peripheral edge 41 is caught between and abuts against the wall surface 62a of the outer wall 62 and the wall surface 69a of the inner wall 69, and cannot be inserted any further.

[0045] In other words, the hairspring 260 allows the insertion position of the hairspring 40 relative to the groove 61 to be set to a constant value by the groove width w3. That is, with conventional hairsprings, the inner circumferential edge 41 of the hairspring 40 protrudes from the other end 61c of the groove 61, and the length of the hairspring 40 protruding from the end 61c must be set using a jig or the like to control the insertion position of the hairspring 40 relative to the hairspring.

[0046] In contrast, in the modified example 2, the hairspring 260 can maintain a constant insertion length of the hairspring 40 inserted into the groove 61 due to the groove width w3 of the groove 61, thus eliminating the need for management using jigs or the like.

[0047] <How to manufacture whisker balls> Next, an example of a preferred manufacturing method for the whisker ball 60 of the embodiments and modified examples described above will be explained. Figures 11, 12, and 13 schematically show the flow of an example of the manufacturing process (manufacturing method) for the whisker ball 260 in a cross-section along the DD line in Figures 5A and 6. The manufacturing method in this example is a LIGA method that includes a novel process. However, the whisker ball according to the present invention is not limited to those manufactured by this LIGA method that includes this novel process.

[0048] (1st coating process) As shown in the upper part of Figure 11, the first resist 110 is applied to the conductive substrate 200. Then, the solvent in the first resist 110 is removed by heating.

[0049] The substrate 200 may be formed from a conductive metal, or it may be a substrate body made of a semiconductor such as silicon, or a substrate body made of a non-conductive resin, on which a conductive film is formed to exhibit conductivity.

[0050] The first resist 110 forms the first mold layer E1, which is the first layer in the thickness direction T. The first mold layer E1 becomes the mold (electroformed mold) that forms the first thickness region 60c (see Figure 7) of the hairball 60 in the thickness direction T. The first resist 110 is formed, for example, from a chemically amplified epoxy-based negative photoresist.

[0051] Furthermore, the first resist 110 is not limited to a negative-type resist in which the portion irradiated with UV light (ultraviolet light) is an insoluble portion that does not dissolve and the portion that is not irradiated is a soluble portion that dissolves. It may also be a positive-type resist (for example, a polymethyl methacrylate-based positive-type photoresist) in which the portion irradiated with UV light is a soluble portion and the portion that is not irradiated is an insoluble portion. The same applies to the second resist 120, which will be described later.

[0052] (First exposure process) Next, as shown in the middle section of Figure 11, the first resist 110 is irradiated (exposed) with UV light L through a photomask 130 having an opening 131 and a shielding portion 132, as indicated by the arrows in the figure. The opening 131 and the shielding portion 132 are formed in a pattern corresponding to the contour shape of the first thickness region 60c of the electroformed product 300 to be manufactured (the whisker ball 60 in the middle section of Figure 13). However, the outer mold portion for forming the weight-reducing holes 67 and the outer contour shape of the whisker ball 60 is formed to extend over the entire length of the whisker ball 60 in the thickness direction T, so it is not exposed in the first exposure step for exposing the first resist 110, but is exposed simultaneously with the second resist 120 in the subsequent second exposure step.

[0053] The first resist 110 has a first exposed region 111, which is the region irradiated with UV light L through the opening 131, and a first unexposed region 112, which is the region that was not irradiated with UV light L by the shielding portion 132.

[0054] (Eaves arrangement process) Next, as shown in the lower part of Figure 11, a canopy portion 140 is placed on a part of the upper surface 110a of the first resist 110. This step of placing the canopy portion 140 is a novel step not found in the conventional LIGA method.

[0055] The eaves portion 140 is a layer having the function of preventing the transmission of UV light, or a layer having the function of preventing the transmission of UV light and the function of preventing reflection. Specifically, a part of the upper surface 110a on which the eaves portion 140 is placed is the area within the first unexposed region 112 of the first resist 110 where the second exposed region 121 of the second resist 120, which will be described later, is formed.

[0056] Later, a second resist 120 is applied to the first resist 110, as shown in the upper part of Figure 12, and the second resist 120 is irradiated (exposed) with UV light L, as shown in the middle part of Figure 12. The transmission prevention function of the eaves portion 140 prevents the UV light irradiated onto the second resist 120 from exposing the first unexposed region 112.

[0057] Furthermore, when UV light L is reflected by the eaves portion 140, the unexposed region (second unexposed region 122) in the second resist 120 is exposed by the reflected UV light L. However, the anti-reflective function of the eaves portion 140 prevents the UV light L from being reflected, thereby preventing the second unexposed region 122 from being exposed.

[0058] The function of the eaves portion 140 in preventing the transmission of UV light L is achieved by forming it with a metal such as copper (Cu) by sputtering, for example. The eaves portion 140 is melted when the electroformed product (whiskers 60) is later separated from the electroformed mold. Therefore, the eaves portion 140 can be formed with a metal material different from the metal material constituting the electroformed product (e.g., nickel), and is not limited to copper.

[0059] The function of preventing the reflection of UV light L from the eaves portion 140 can be achieved, for example, by surface treatment that forms fine irregularities on the surface of the eaves portion 140, or by applying an anti-reflective coating. Alternatively, it may be configured as a two-layer structure in which a transmission-preventing layer 141 having the function of preventing transmission is formed, and an anti-reflective layer 142 having the function of preventing reflection is formed on top of it.

[0060] In this case, the anti-reflective layer 142 may be made of, for example, an organic ARC (Anti-Reflection Coating) material, an inorganic ARC material, or a film with a micro-protrusion array. The anti-reflective layer 142 can be formed by sputtering, CVD, vacuum deposition, spin coating, or the like.

[0061] Furthermore, the eaves portion 140 shown in the lower part of Figure 11 extends not only to the area within the first unexposed region 112 of the first resist 110 where the second exposed region 121 of the second resist 120 is formed, but also to a part of the first exposed region 111 adjacent to the first unexposed region 112 of the first resist 110. The reason why the eaves portion 140 extends to a part of the first exposed region 111 adjacent to the first unexposed region 112 is as follows.

[0062] In other words, if the eaves portion 140 is formed only in the area of ​​the first unexposed region 112 where the second exposed region 121 of the second resist 120 is formed, UV light L diffracted at the edge of the eaves portion 140 on the side of the first exposed region 111 adjacent to the first unexposed region 112 may propagate into the first unexposed region 112 and expose it. Therefore, in order to prevent the first unexposed region 112 from being exposed by the diffracted UV light L, it is preferable that the eaves portion 140 is formed to extend to a part of the first exposed region 111 adjacent to the first unexposed region 112.

[0063] However, the eaves portion 140 only needs to be formed in the area where the second exposed region 121 of the second resist 120 is formed within the first unexposed region 112 of the first resist 110, and does not need to extend to a part of the first exposed region 111 adjacent to the first unexposed region 112 of the first resist 110.

[0064] (2nd coating process) Next, as shown in the upper part of Figure 12, the second resist 120 is applied on top of the first resist 110, including over the eaves portion 140.

[0065] The second resist 120 forms the second mold layer E2, which is the second layer in the thickness direction T. The second mold layer E2 becomes the mold (electroformed mold) that forms the second thickness region 60d (see Figure 7) of the hairball 60 in the thickness direction T. The second resist 120 is formed, for example, from a chemically amplified epoxy-based negative photoresist.

[0066] Furthermore, the second resist 120 is not limited to a negative type, and may be, for example, a polymethyl methacrylate-based positive type photoresist. However, from the viewpoint of simplifying the process, it is preferable that the first resist 110 and the second resist 120 are made of the same material, such that the second resist 120 is also negative type when the first resist 110 is negative type, and the second resist 120 is also positive type when the first resist 110 is positive type.

[0067] (Second exposure process) Next, as shown in the middle section of Figure 12, UV light L is irradiated (exposed) onto the second resist 120 through a photomask 150 having an opening 151 and a shielding portion 152, as indicated by the arrows in the figure. The opening 151 and the shielding portion 152 are formed in a pattern corresponding to the contour shape of the second thickness region 60d of the electroformed product 300 to be manufactured (the whisker ball 60 in the middle section of Figure 13). The outermost part of the opening 151 forms the second exposure region 121, which corresponds to the outer mold portion for forming the outer contour shape of the whisker ball 60.

[0068] The second resist 120 is divided into a second exposed region 121, which is the region irradiated with UV light L through the opening 151, and a second unexposed region 122, which is the region that was not irradiated with UV light L by the shielding portion 152.

[0069] Furthermore, the UV light L irradiated through the aperture 151 also exposes the area directly below the second exposure area 121 within the first unexposed area 112 of the first resist 110, so the area of ​​the first unexposed area 112 of the first resist 110 that has been exposed in this manner becomes the first exposure area 111.

[0070] In this way, the first exposure region 111, which is formed by exposure simultaneously with the second exposure region 121 through the second exposure region 121, corresponds to, for example, the mold portion for the weight-reducing hole 67 or the outer mold frame portion for forming the outer contour shape of the whisker ball 60. Furthermore, in the mold portion where the first exposure region 111 and the second exposure region 121 are formed simultaneously in this way, no seam boundary line is formed at the boundary between the first exposure region 111 and the second exposure region 121, thus improving the appearance quality.

[0071] In the second exposure step, when a second exposure region 121 is formed that protrudes in the width direction from the first exposure region 111, that is, in an electroforming mold in which the second exposure region 121 is positioned on the first unexposed region 112, the UV light L that has passed through the second exposure region 121 is directed toward the first unexposed region 112 in the lower layer.

[0072] Since a eaves portion 140 is formed at the boundary between the second exposed region 121 and the first unexposed region 112 formed in the lower layer, UV light L that has passed through the second exposed region 121 does not pass through the eaves portion 140 and therefore does not expose the first unexposed region 112. Accordingly, this method can accurately form the contour shape of the first unexposed region 112.

[0073] Furthermore, since the eaves portion 140 does not reflect light, UV light L that has passed through the second exposure region 121 is not reflected by the eaves portion and does not expose the second unexposed region 122. Therefore, this method can accurately form the contour shape of the second unexposed region 122.

[0074] (Development process) Next, as shown in the lower part of Figure 12, the first unexposed region 112 of the first resist 110 and the second unexposed region 122 of the second resist 120 are removed by the development process. This forms an electroformed mold 180 consisting of the first exposed region 111 and the second exposed region 121, and cavities corresponding to the first unexposed region 112 (indicated by the parenthetical notation (112) in Figure 12) and the second unexposed region 122 (indicated by the parenthetical notation (122) in Figure 12).

[0075] The electroformed mold 180 forms a first mold layer E1 with a cavity (112) corresponding to a first exposed region 111 and a first unexposed region 112, and forms a second mold layer E2 with a cavity (122) corresponding to a second exposed region 121 and a second unexposed region 122. Therefore, the first mold layer E1 and the second mold layer E2 have different contour shapes at positions along the thickness direction T.

[0076] In addition, when the first unexposed region 112 and the second unexposed region 122 are removed by the development process, or at the same time, or afterward, a part (transparency-preventing layer 141) or all of the eaves portion 140 may be removed.

[0077] (Plating process) Next, as shown in the upper part of Figure 13, electroplating with nickel is performed between the electroforming mold 180 and the substrate 200. The electroplating material used to form the electroformed product 300 is not limited to nickel; any material that can be electroplated, such as gold, copper, tin, or cobalt, may be used.

[0078] In this electroplating process, the electroplating material grows from the substrate 200 side into the cavity (112) corresponding to the first unexposed region 112 and the cavity (122) corresponding to the second unexposed region 122, thereby forming the electroformed product 300. Note that the plating process corresponding to the first type layer E1 and the plating process corresponding to the second type layer E2 are not separated but carried out as a single continuous process.

[0079] (Electroformed product extraction process) After the electroplating has grown to the upper surface of the second mold layer E2, as shown in the upper part of Figure 13, the upper surface 120a of the second resist 120 is ground and polished flat together with the upper surface of the second mold layer E2. Then, the first exposure region 111 constituting the first mold layer and the second exposure region 121 constituting the second mold layer E2 are removed, and the substrate 200 is also removed, thereby extracting the electroformed product 300 formed as whisker balls 60, as shown in the lower part of Figure 13.

[0080] Thus, the whisker ball 60 manufactured by the LIGA method, which includes a novel process, is formed by continuously creating a first thickness region 60c corresponding to the first type layer E1 and a second thickness region 60d corresponding to the second type layer E2, without separating them.

[0081] Therefore, the strength of the whisker ball 60 at the boundary between the first thickness region 60c and the second thickness region 60d is stronger than the strength at the boundary between the first thickness region 60c and the second thickness region 60d in a whisker ball 60 that is formed discontinuously by separating the first thickness region 60c and the second thickness region 60d.

[0082] As a result, even when the outer wall portion 62 is pressed and deformed toward the inner wall portion 69 in order to temporarily fix the hairspring 40 in the groove 61, it is possible to prevent the outer wall portion 62 from breaking or fracturing at the boundary between the first thickness region 60c and the second thickness region 60d.

[0083] Furthermore, because the whisker bulbs 60 manufactured using the LIGA method are minute parts, it is possible to form weight-reducing holes 65, 66, 67, etc., which are difficult to form by machining, with high precision. [Explanation of Symbols]

[0084] 20 Tenshin 40 Hairspring 41a Inner edge 60 Beard Balls 61 Groove 62 Outer wall section 63 Through hole 69 Inner wall section C center axis

Claims

1. A through hole formed in the center, into which the balance staff is fixed, Near the outer edge, there is a groove formed along the circumferential direction of the inner end of the hairspring to be attached, into which the inner end is inserted. The radially outer wall portion that partitions the groove, centered on the central portion, is deformable toward the radially inner wall portion. As the outer wall deforms, the inner circumferential end of the hairspring inserted into the groove is temporarily fixed by being sandwiched between the inner wall and the outer wall. A hairspring ball, wherein a taper is formed on the outer wall portion of the end of the groove furthest from the inner circumference edge, such that when the hairspring is attached to the groove, the groove width at the end furthest from the inner circumference edge of the hairspring is wider than the groove width at the end furthest from the inner circumference edge of the hairspring.

2. The through hole comprises a fitting portion into which the balance staff is fitted, and an introduction hole coaxially arranged with the fitting portion and having a larger inner diameter than the fitting portion. When the region along the thickness direction is divided into a first thickness region, where the inner wall portion and the outer wall portion that partition the groove are formed, and a second thickness region, where the bottom wall portion that partitions the groove is formed, The fitting portion is formed in the first thickness region, The whisker ball according to claim 1, wherein the introduction hole is formed in the second thickness region.

3. The whisker bulb according to claim 2, wherein the fitting portion is formed by a plurality of protruding portions that extend radially inward from a circumferential surface having the same inner diameter as the introduction hole.

4. In a plan view, it is formed in a roughly triangular shape with protrusions projecting outward in the radial direction at three locations around the through hole. The groove is formed in one of the three protrusions. The whisker head according to any one of claims 1 to 3, wherein each of the three protruding portions has a weight-reducing hole formed through it in the thickness direction.

5. The hairspring ball according to any one of claims 1 to 3, wherein the inner wall portion is formed in a contour shape along the circumferential direction of the inner end portion of the hairspring.

6. A through hole formed in the center, into which the balance staff is fixed, Near the outer edge, there is a groove formed along the circumferential direction of the inner end of the hairspring to be attached, into which the inner end is inserted. The radially outer wall portion that partitions the groove, centered on the central portion, is deformable toward the radially inner wall portion. As the outer wall deforms, the inner circumferential end of the hairspring inserted into the groove is temporarily fixed by being sandwiched between the inner wall and the outer wall. In a plan view, it is formed in a roughly triangular shape with protrusions projecting outward in the radial direction at three locations around the through hole. The groove is formed in one of the three protrusions. A whisker ball, in which each of the three aforementioned protrusions has a weight-reducing hole formed through it in the thickness direction.

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