Gear assembly, timepiece and method for manufacturing gear assembly

Abstract

To suppress manufacturing cost.SOLUTION: A gear assembly 40 includes a shaft 40A, a silicon gear 40B inserted into the shaft 40A, and a caulking member 40D for caulking the gear 40B to the shaft 40A.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a gear assembly, a timepiece, and a method for manufacturing a gear assembly. [Background technology]

[0002] The gear train mechanism of a wristwatch or the like uses many gears of different shapes and sizes (see, for example, Patent Document 1). In particular, high-priced products tend to be produced in small quantities and with a wide variety of items, which means that manufacturing costs, including development costs, tend to be high. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-30092 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention has been made in consideration of the above circumstances, and has an object to reduce manufacturing costs. [Means for solving the problem]

[0005] In order to achieve the above object, the present invention provides a gear assembly, A shaft, A silicon gear inserted into the shaft; a crimping member for crimping the gear to the shaft; Equipped with. Effect of the Invention

[0006] According to the present invention, the manufacturing costs can be reduced. [Brief description of the drawings]

[0007] [Figure 1] FIG. 2 is a front view showing the main parts of the timepiece according to the embodiment. [Diagram 2] 4 is a cross-sectional view of the gear train mechanism of the hour hand drive mechanism in the timepiece according to the embodiment. FIG. [Diagram 3] FIG. 2 is a cross-sectional view of an example of a gear assembly according to the embodiment. [Figure 4] FIG. 2 is a cross-sectional view of an example of a gear assembly according to the embodiment. [Diagram 5] 5A and 5B are plan views of a gear according to an embodiment, in which (a) is a single-item view, (b) is a view showing a state in which the circumferential orientation of the shaft with respect to the pinion is correct, and (c) is a view showing a state in which the circumferential orientation with respect to the pinion is misaligned. [Figure 6] 4 is a flowchart showing the steps of a method for manufacturing a timepiece according to an embodiment. [Figure 7] FIG. 1 is a diagram showing an example of a silicon wafer onto which the shapes of multiple gears and pinions are transferred by photolithography. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] An embodiment of the present invention will be described with reference to the drawings. In addition, the embodiments described below are subject to various limitations that are technically preferable for implementing the present invention, but the scope of the present invention is not limited to the following embodiments and illustrated examples.

[0009] [Overall clock configuration] Fig. 1 is a front view showing the main parts of a timepiece 100 according to this embodiment. Note that in Fig. 1, the dial and part of the main plate 21 are omitted in order to make the main structure easier to understand.

[0010] As shown in Fig. 1, the timepiece 100 according to this embodiment is an analog timepiece that displays time by using multiple hands 3 (second hand 3s, minute hand 3m, hour hand 3h) to point to hour characters 102. The timepiece 100 has a main body case 101 formed into a short cylindrical shape when viewed from the front. The main body case 101 accommodates a plurality of hands 3, a plurality of drive mechanisms 30 for driving and rotating the plurality of hands 3 individually, and the like.

[0011] The multiple drive mechanisms 30 include a second hand drive mechanism 30s that drives and rotates the second hand 3s, a minute hand drive mechanism 30m that drives and rotates the minute hand 3m, and an hour hand drive mechanism 30h that drives and rotates the hour hand 3h. Each drive mechanism 30 includes a motor 32 which is a drive source, and a gear train mechanism 33 which transmits the driving force of the motor 32 to the hands 3. Specifically, the second hand drive mechanism 30s includes a first motor 32s and a first gear train mechanism 33s, the minute hand drive mechanism 30m includes a second motor 32m and a second gear train mechanism 33m, and the hour hand drive mechanism 30h includes a third motor 32h and a third gear train mechanism 33h.

[0012] Each gear train mechanism 33 includes a plurality of gear assemblies 40 . For example, the first train wheel mechanism 33s of the second hand drive mechanism 30s includes a gear assembly 40 such as a second wheel (second hand wheel). The second train wheel mechanism 33m of the minute hand drive mechanism 30m includes a gear assembly 40 such as a center wheel (minute hand wheel). The third train wheel mechanism 33h of the hour hand drive mechanism 30h includes a gear assembly 40 such as a minute wheel and an hour wheel (hour hand wheel). The gear train mechanism 33 may include gears other than the gear assembly 40. In this case, the gears need only include at least a gear and a shaft. The gear and the shaft may be separate parts as long as they are integral with each other.

[0013] [Gear assembly configuration] The configuration of the third gear train mechanism 33h of the hour hand drive mechanism 30h will be described below as an example of the gear assembly 40 according to this embodiment. FIG. 2 is a cross-sectional view of the third gear train mechanism 33h in the timepiece 100. As shown in FIG. As shown in this figure, the third wheel train mechanism 33h includes a first hour intermediate wheel 51, a second hour intermediate wheel 52, and a minute wheel 53 as a gear assembly 40. Each of these gear assemblies 40 includes a shaft 40A which is a rotating shaft, a gear 40B which transmits torque, a pinion 40C which has a smaller diameter than the gear 40B, a crimping member 40D which fixes other components to the shaft 40A, and a spacer 40E which adjusts the axial positions of the gear 40B and the pinion 40C. However, the gear assembly according to the present invention only needs to include at least the shaft, the gear, and the crimping member. There may be a plurality of components other than the shaft. In the following, the components of the gear assembly 40 will be identified by adding the following suffix to the reference numerals: shaft ("A"), gear ("B"), pinion ("C"), crimping member ("D"), and spacer ("E") (for example, the shaft of the first intermediate wheel 51 is designated "51A"). Hereinafter, the front-to-back direction of the timepiece 100 will be referred to as the up-down direction, with the front side (lower side in FIG. 2) being referred to as the "lower side" and the rear side (upper side in FIG. 2) being referred to as the "upper side".

[0014] In the third wheel train mechanism 33h, the rotational force of the third motor 32h is transmitted in this order to the first hour intermediate wheel 51, the second hour intermediate wheel 52, the minute wheel 53, and the hour wheel 54, thereby rotating the hour hand 3h. The first hour intermediate wheel 51 has a shaft 51A, a gear 51B, a pinion 51C, a crimped member 51D, and a plurality of spacers 51E. The shaft 51A is rotatably supported at both ends by the main plate (base plate) 21 and the train wheel receiver 22. The train wheel receiver 22 is disposed above the main plate 21, and supports the upper end of the shaft 51A. The gear 51B meshes with a rotor pinion 51e of the third motor 32h. The pinion 51C is connected to the second hour intermediate wheel 52. The components of the gear assembly 40 will be described in detail later.

[0015] The second hour intermediate wheel 52 has a shaft 52A, a gear 52B, a pinion 52C, a crimped member 52D, and a plurality of spacers 52E. The shaft 52A is rotatably supported at both ends by the train wheel bridge 22 and the date indicator holder 24. The date indicator holder 24 is disposed below the main plate 21, and supports the lower end of the shaft 52A. The gear 52B meshes with the pinion 51C of the first hour intermediate wheel 51. The pinion 52C is connected to the minute wheel 53. The minute wheel 53 has a shaft 53A, a gear 53B, a pinion 53C, and a spacer 53E. The shaft 53A is rotatably supported at both ends by the main plate 21 and the date dial holder 24. The gear 53B meshes with the pinion 52C of the second intermediate wheel 52. The pinion 53C is connected to the hour wheel 54. The hour wheel 54 has a cylindrical hour wheel body 54a to the bottom end of which the hour hand 3h is fixed, and an hour gear 54b formed integrally with the hour wheel body 54a and meshing with the pinion 53C of the minute wheel 53. As a result, the rotational force of the third motor 32h is transmitted to the hour wheel 54 via the first hour intermediate wheel 51, the second hour intermediate wheel 52, and the minute wheel 53, causing the hour hand 3h at the bottom end of the hour wheel body 54a to rotate.

[0016] A center wheel 61 and a fourth wheel 71 are inserted inside the hour wheel 54 and are arranged coaxially. The center wheel & pinion 61 has a cylindrical center wheel body 61a and a center gear 61b. The center wheel body 61a is supported rotatably independent of the hour wheel 54 and the second wheel & pinion 71, and the minute hand 3m is fixed to the lower end. The center gear 61b is fixed to the upper end of the center wheel & pinion body 61a and is connected to the second motor 32m. As a result, the rotational force of the second motor 32m is transmitted to the center wheel & pinion 61, and the minute hand 3m at the lower end of the center wheel & pinion body 61a rotates. The second wheel & pinion 71 has an axial second wheel body 71a and a second gear 71b. The second wheel body 71a is inserted into the second wheel body 61a and is supported rotatably independent of the hour wheel 54 and the second wheel & pinion 61, and the second hand 3s is fixed to the lower end. The second gear 71b is fixed to the upper end of the second wheel & pinion body 71a and is connected to the first motor 32s. As a result, the rotational force of the first motor 32s is transmitted to the second wheel & pinion 71, and the second hand 3s at the lower end of the second wheel & pinion body 71a rotates.

[0017] Each component of the gear assembly 40 will now be described in detail. 3 and 4 are cross-sectional views of an example of the gear assembly 40. FIG.

[0018] <Shaft> As shown in FIG. 3, the shaft 40A is an axis component made of, for example, carbon tool steel (SK material), and has a supported portion 40Aa, an insertion portion 40Ab, and a flange portion 40Ac. The supported portions 40Aa are rotatably supported portions, and are provided, for example, on both axial ends. The insertion portion 40Ab is a portion through which the gear 40B, the pinion 40C, the crimping member 40D, and the spacer 40E are inserted. The insertion portion 40Ab has a cross section formed, for example, in a polygonal shape (hexagonal in the example of Figs. 3 and 4) to prevent relative rotation with the inserted part. The gear 40B, the pinion 40C, the crimping member 40D, and the spacer 40E each have an insertion hole in the center thereof, the shape of which is approximately the same as the cross section of the insertion portion 40Ab. Fig. 5 shows an insertion hole 40Ba of the gear 40B as an example. The flange portion 40Ac is disposed, for example, at an axial end of the insertion portion 40Ab. The flange portion 40Ac abuts against and positions the gear 40B, the pinion 40C, or the spacer 40E through which the insertion portion 40Ab is inserted in the axial direction. A recessed escape groove 40Ad is formed on the inner diameter side of the corner of the flange 40Ac that abuts against the gear 40B or the spacer 40E, that is, the boundary between the insertion portion 40Ab of the shaft 40A and the flange 40Ac that has a larger diameter than the insertion portion 40Ab. That is, the recessed escape groove 40Ad is provided by forming the shaft 40A to have a smaller diameter than the insertion portion 40Ab. However, the escape groove 40Ad may have any shape as long as it can escape (avoid contact with) the corner of the inner diameter side of the gear 40B, the pinion 40C, or the spacer 40E.

[0019] 4, the shaft 40A may have a pinion (small gear) 40Ap integrally therewith. In this case, the pinion 40Ap may be used to position the gear 40B or the spacer 40E in the axial direction instead of the flange 40Ac. In this case, it is preferable to provide a clearance groove 40Ad at the corner of the inner diameter side of the pinion 40Ap.

[0020] In the gear train mechanism 33, multiple shafts 40A are supported by several common parts (substrates). For example, in the case of the third gear train mechanism 33h, as shown in FIG. 2, each shaft 40A is supported by any two of the main plate 21, the gear train holder 22, and the date indicator holder 24. Therefore, when only the vertical (axial) length is used as a reference, the shafts 40A can be broadly divided into those from the gear train holder 22 to the main plate 21, those from the gear train holder 22 to the date indicator holder 24, and those from the main plate 21 to the date indicator holder 24. In other words, the shafts 40A can be shared by multiple gear assemblies 40 that share a common supporting substrate. It goes without saying that the shafts 40A can be shared with other gear train mechanisms 33 as long as the supporting substrate (or its axial position) is common.

[0021] <Gears and pinions> Figure 5 is a plan view of gear 40B, where (a) is a single-item view, (b) is a view showing a state in which the circumferential orientation of shaft 40A with pinion 40Ap is correct, and (c) is a view showing a state in which the circumferential orientation with pinion 40Ap is misaligned. 5(a) and (b), the gear 40B and the pinion 40C are both spur gears made of, for example, silicon, and the pinion 40C is a gear with a smaller diameter than the gear 40B. The gear 40B and the pinion 40C of this embodiment are fabricated from a silicon wafer by photolithography, as described below.

[0022] The gear 40B has an insertion hole 40Ba in the center, through which the shaft 40A is inserted. The insertion hole 40Ba is formed in a polygonal shape corresponding to the insertion portion 40Ab of the shaft 40A. A hand position detection hole T1 is formed in the gear 40B at a predetermined position on the outer periphery, penetrating in the thickness direction. The hand position detection holes T1 formed in multiple gears 40B stacked vertically overlap at a predetermined timing (period) during hand movement. At this time, light from the light emitting section passes through the hand position detection holes T1 stacked on the multiple gears 40B and is detected by the light receiving section, thereby detecting the position of the pointer 3.

[0023] A first mark M1 for identifying the gear type is formed around the insertion hole 40Ba of the gear 40B. The first marks M1 vary in hole shape, number, position, etc., depending on the type of the gear 40B. In addition, the gear 40B is formed with a second mark M2 for determining the direction. However, in the gear 40B in which the needle position detection hole T1 is formed, the direction is determined by the needle position detection hole T1, and the second mark M2 does not have to be provided. The positions, number, shapes, etc. of the first mark M1 and the second mark M2 are not particularly limited. However, if these are arranged near the needle position detection hole T1, the light transmitted through the first mark M1 and the second mark M2 may cause erroneous detection. Therefore, it is preferable that the first mark M1 and the second mark M2 are formed near the insertion hole 40Ba.

[0024] Further, the gear 40B is formed with a third mark M3 for aligning the circumferential orientation with the pinion 40C (or the pinion 40Ap). The third mark M3 is formed at the position of the teeth (mountains) of the pinion 40C of the gear 40B when the pinion 40C is assembled in the proper circumferential direction. Therefore, as shown in FIG. 5(b), when the gear 40B and the pinion 40C are assembled in the proper circumferential direction, the third mark M3 is covered by the teeth of the pinion 40C. On the other hand, as shown in FIG. 5(c), when the circumferential direction of the pinion 40C is deviated from the proper position by, for example, one pitch of the insertion hole 40Ba, the third mark M3 is exposed from the valley of the pinion 40C. This allows an assembler (or an inspector) to easily determine whether the gear 40B and the pinion 40C are assembled properly based on whether the third mark M3 is exposed from the pinion 40C. The needle position detection hole T1 may also serve as the third mark M3 (or its function).

[0025] It is preferable that the first mark M1, the second mark M2, and the third mark M3 are formed as small as possible so as not to excessively reduce the strength of the gear 40B. For example, when the gear 40B is produced using a photoresist mask, it is preferable that the size of the marks is about φ0.05 to φ0.1 mm, which is the limit of processing accuracy. However, it goes without saying that the size must be such that an operator can visually confirm the marks during assembly.

[0026] The gear 40B and the pinion 40C are fixed to the shaft 40A integrally (or individually) with other components by a crimping member 40D. Alternatively, the gear 40B and the pinion 40C may be fixed to the shaft 40A by an adhesive. In this case, the relief groove 40Ad of the shaft 40A can be used as a groove for collecting the adhesive, and the excess adhesive can be prevented from spilling out. Alternatively, the gear 40B and the pinion 40C may be made of a ductile material such as nickel or brass, and fixed to the shaft 40A by press-fitting. The pinion 40C may be divided into a plurality of pieces in the axial direction, that is, a plurality of pinions 40C may be stacked in the axial direction to increase the thickness.

[0027] <Crimping parts> 3 and 4, the crimping member 40D is press-fitted onto the shaft 40A, and the gear 40B, the pinion 40C, and the spacer 40E are crimped (swaged) to the shaft 40A. The crimping member 40D is formed in a short ring shape with a thickness of, for example, about 0.1 mm. The material (raw material) of the crimping member 40D is not particularly limited as long as it can be press-fitted onto the shaft 40A, and is, for example, nickel. When gear 40B and pinion 40C are fixed to shaft 40A by press fitting, crimping member 40D may be omitted.

[0028] <Spacer> The spacer 40E is formed in a cylindrical shape and is inserted onto the shaft 40A to adjust the axial positions of the gear 40B and the pinion 40C. The axial length of the spacer 40E is not particularly limited. A plurality of short spacers 40E may be combined and inserted onto one shaft 40A. When the spacer 40E is disposed between the gear 40B and the pinion 40C, it is preferable that the size of the spacer 40E has a diameter smaller than the root circle of the gear 40B and the pinion 40C. This allows the height of the pinion 40C to be freely adjusted to an optimal value according to needs while ensuring a gap in the height direction between the interlocking gears 40B. The material of the spacers 40E is not particularly limited, but may be, for example, silicon, nickel, brass, etc. For example, the spacers 40E made of silicon by photolithography have a high degree of smoothness on the end faces, so that tilt can be suppressed even when multiple spacers are stacked.

[0029] [Manufacturing method] FIG. 6 is a flow chart showing the steps of a method for manufacturing a timepiece 100 including a gear assembly 40, and FIG. 7 is a diagram showing an example of a silicon wafer W onto which the shapes of multiple gears 40B and pinions 40C have been transferred by photolithography. As shown in FIG. 6, in the method of manufacturing the timepiece 100, first, the gear 40B and pinion 40C are produced by lithography (step S1).

[0030] 7, in this step, multiple types of gears 40B and pinions 40C used in one timepiece 100 are made from one silicon wafer W. The thickness of the silicon wafer W is at most about 0.1 to 0.15 mm. At this time, the gears 40B and pinions 40C are arranged (distributed) such that gears with larger diameters are located closer to the center line L that divides the silicon wafer W into approximately two halves. The width (length in the direction perpendicular to the center line L) of each row of the gears 40B and pinions 40C is made as constant as possible along the center line L. This allows the gears 40B and pinions 40C to be arranged so as to prevent the generation of unnecessary excess space on the approximately circular silicon wafer W. However, the arrangement of the gears 40B and pinions 40C on the silicon wafer W may be appropriately adjusted so as to minimize excess space on the silicon wafer W. Also, the spacer 40E may be fabricated from the same silicon wafer W together with the gear 40B and the pinion 40C.

[0031] Next, as shown in FIG. 6, each gear assembly 40 is assembled (step S2). Here, the gear assembly 40 is assembled by inserting the gear 40B, the pinion 40C and the spacer 40E onto the shaft 40A, and then press-fitting the crimping member 40D. At this time, the assembly worker checks the first mark M1 on the gear 40B to determine its type, and combines it with the corresponding shaft 40A, pinion 40C, etc. At this time, the assembler checks the third mark M3 of the gear 40B and assembles the pinion 40C to the gear 40B so that the third mark M3 is covered by the teeth of the pinion 40C (or the pinion 40Ap). This allows the gear 40B and the pinion 40C (or the pinion 40Ap) to be assembled in a proper circumferential relationship.

[0032] Next, the entire watch 100 is assembled (step S3). Here, the gear train mechanism 33 made up of the multiple gear assemblies 40 assembled in step S3, and a module including the hands 3, etc. are assembled into the main body case 101. Furthermore, for example, a timing circuit, a battery block, etc. in the case of an electronic timepiece, and an escape wheel, a hairspring, etc. in the case of a mechanical timepiece are assembled as necessary. In this manner, the watch 100 is assembled.

[0033] [Technical effect of the present embodiment] As described above, according to this embodiment, the gear assembly 40 includes the shaft 40A, the silicon gear 40B, and the crimping member 40D for crimping the gear 40B to the shaft 40A. If a metal gear is used, the structure would be complicated, so a crimping member is not used. Instead, the inner diameter of the metal gear is formed slightly smaller than the outer diameter of the shaft, and the gear is crimped to the shaft by press-fitting. On the other hand, in the case of the silicon gear 40B, the gear 40B cannot be crimped to the shaft by press-fitting because it is made of a hard material, but by using the crimping member 40D, the gear 40B can be crimped to the shaft 40A even if it is made of silicon. This allows the silicon gear 40B to be adopted. In addition, the above-mentioned configuration allows the shaft 40A to be shared among a plurality of different types of gear assemblies 40 by simply replacing the gear 40B. Therefore, even in the case of small-volume, high-mix products, the development period and development costs can be reduced. In turn, the manufacturing costs, including the development costs, can be reduced. In addition, the use of silicon gear 40B reduces friction because it is harder and has a smoother surface than metal or resin gears, and therefore reduces power consumption (energy consumption) when moving the hands. In particular, the power consumption required to drive the second hand 3s is greater than that of the other hands 3, so applying silicon gear 40B to the second hand drive mechanism 30s is particularly effective. The reduced friction of gear 40B also reduces backlash, improving the positioning accuracy of the hands 3.

[0034] Furthermore, according to this embodiment, the gear assembly 40 includes the pinion 40C made of silicon and having a smaller diameter than the gear 40B, and the crimping member 40D crimps the pinion 40C to the shaft 40A. That is, the pinion 40C can be separated from the shaft 40A. This makes it possible to reduce the number of pinion shafts, which are particularly expensive to develop, and therefore further reduce manufacturing costs, including development costs.

[0035] Furthermore, according to this embodiment, the gear 40B has a third mark M3 for aligning the circumferential orientation with the pinion 40C. The third mark M3 is formed at a position that is covered by the teeth of the pinion 40C when the pinion 40C is assembled in the correct circumferential orientation, and is exposed between the teeth of the pinion 40C when the pinion 40C is not assembled in the correct circumferential orientation. This allows an assembly worker to easily determine whether the gear 40B and the pinion 40C are assembled in the correct circumferential orientation (relative rotation angle) by checking whether the third mark M3 is exposed from the pinion 40C. When detecting the position of the pointer 3, the gears 40B are rotated to a position where the needle position detection holes T1 overlap each other, and the position of the pointer 3 is detected based on the amount of light passing through the needle position detection holes T1 at this time. If the gears 40B and the pinion 40C are assembled in a proper circumferential direction, the needle position detection holes T1 are also assembled in a proper weekly direction, and thus the needle position detection holes T1 overlap as expected when detecting the position of the pointer 3, maximizing the amount of light passing through the needle position detection holes T1. This makes it possible to detect the position of the pointer 3 with high accuracy. Conversely, if the gears 40B and the pinion 40C are not assembled in a proper circumferential direction, the needle position detection holes T1 are also not assembled in a proper weekly direction, and as a result, the position of the pointer 3 cannot be detected correctly.

[0036] Furthermore, according to this embodiment, the gear assembly 40 includes the spacer 40E through which the shaft 40A is inserted. As a result, while the shaft 40A is shared among a plurality of gear assemblies 40, the heights (axial positions) of the gears 40B and pinions 40C can be individually adjusted by the spacers 40E.

[0037] Furthermore, according to this embodiment, the shaft 40A has a clearance groove 40Ad at a corner on the inner diameter side of the surface of the flange portion 40Ac that comes into contact with the gear 40B. This makes it possible to prevent damage to the corners on the inner diameter side of the gear 40B due to contact with the corners on the inner diameter side of the flange portion 40Ac of the shaft 40A. That is, the silicon gear 40B is very hard and is manufactured by photolithography, so that the corners are easily chipped when stress is concentrated, and it is difficult to chamfer the corners. Therefore, it is undesirable that the corners on the inner diameter side of the flange portion 40Ac have corner R that may interfere (contact) with the gear 40B when assembled. However, when the flange portion 40Ac is formed by normal cutting, it is unavoidable that the corner R is formed at the corners on the inner diameter side of the flange portion 40Ac. Therefore, the corner R is removed by performing additional cutting in the radial direction (toward the inner diameter) on the corners on the inner diameter side of the flange portion 40Ac, and the escape groove 40Ad, which has a smaller diameter than the insertion portion 40Ab, is provided in the shaft 40A. This makes it possible to avoid interference between the shaft 40A and the gear 40B when assembled. This makes it possible to suitably assemble the gear 40B to the shaft 40A without making the gear 40B smaller to avoid the corner R and making it difficult to position the gear 40B. That is, the gear 40B can be positioned with high precision both in the axial direction and in the radial direction. The processing direction of the clearance groove 40Ad is preferably the radial direction (toward the inner diameter). If the clearance groove 40Ad is processed in the axial direction, a hexagonal undercut corresponding to the shape of the insertion portion 40Ab is required. On the other hand, by processing the clearance groove 40Ad in the radial direction (toward the inner diameter), the clearance groove 40Ad can be formed by cutting relatively easily. Furthermore, when the gear 40B is joined to the shaft 40A with an adhesive, the clearance groove 40Ad can be used as a groove for collecting the adhesive. This makes it possible to prevent excess adhesive from spilling out of the gap between the shaft 40A and the gear 40B and the clearance groove 40Ad. This in turn makes it possible to prevent malfunctions caused by the spilled adhesive.

[0038] Moreover, according to this embodiment, a plurality of types of gears 40B and pinions 40C are fabricated from one silicon wafer W by photolithography. This allows multiple types of gears 40B and pinions 40C to be suitably manufactured while the shaft 40A is common to multiple gear assemblies 40. Therefore, even in the case of small-volume, high-mix products, the development period and development costs can be reduced, and thus the manufacturing costs, including the development costs, can be reduced. Furthermore, since multiple types of gears 40B and pinions 40C are fabricated from one silicon wafer W by photolithography, these components can be formed to have the same thickness dimension (vertical length). In addition, the main surface of the silicon wafer W (the surface normal to the thickness direction of the silicon wafer W) has a high degree of smoothness. As a result, even when multiple pieces of one or more of the gears 40B, pinions 40C, crimping members 40D, and spacers 40E are stacked, the gear assembly 40 can be formed so that the thickness dimension after stacking is as targeted with high precision. Therefore, even when the third wheel train mechanism 33h is produced by combining the first hour intermediate wheel 51, the second hour intermediate wheel 52, and the minute wheel 53 as in this embodiment, the heights (vertical positions) of the first hour intermediate wheel 51, the second hour intermediate wheel 52, and the minute wheel 53 that mesh with each other can be set with high precision. Furthermore, since the main surfaces (surfaces having the vertical direction as the normal direction) of gear 40B, pinion 40C, crimping member 40D, and spacer 40E have a high degree of smoothness, loss of power energy due to friction between the main surfaces is kept extremely low.

[0039] Furthermore, according to this embodiment, the multiple gears 40B and pinions 40C are arranged on one silicon wafer W such that the gears 40B and pinions 40C with larger diameters are located closer to the center line L of the silicon wafer W. In this case, the gears 40B and pinions 40C with the same diameter are arranged in a direction parallel to the center line L of the silicon wafer W. This makes it possible to suitably arrange the multiple gears 40B and pinions 40C on the silicon wafer W, thereby reducing unnecessary excess space on the silicon wafer W. This makes it possible to further reduce manufacturing costs.

[0040] Furthermore, according to this embodiment, the spacer 40E is fabricated from the same silicon wafer W as the gear 40B and the pinion 40C. This allows the manufacturing costs to be further reduced.

[0041] [others] Incidentally, the embodiments to which the present invention can be applied are not limited to the above-described embodiments, and it goes without saying that various modifications are possible without departing from the gist of the present invention.

[0042] For example, in the above embodiment, the gear and pinion (and / or the spacer) are made of silicon and fabricated by photolithography. However, the material of the gear and pinion (and / or the spacer) is not limited to silicon, and the fabrication method is not limited to photolithography. For example, they may be made of nickel or brass by electroforming. Even if they are electroformed, they are about the same thickness as a silicon wafer. In this case, the gear and pinion can be press-fitted onto the shaft, so the crimping member may be omitted. However, because nickel is a magnetic material, the gear that meshes with the motor does not apply to the pinion.

[0043] Furthermore, the gear assembly according to the present invention is not limited to use in wheel train mechanisms of timepieces, but can be widely applied to anything in which a shaft is inserted through a gear, and is particularly suitable for use in small gear mechanisms in which it is difficult to employ a complex bearing structure. [Explanation of symbols]

[0044] 100 Watches 101 Main body case (case) 3 Guidelines 32 Motor 33 Wheel train mechanism 40 Gear assembly 40A Shaft 40Aa Supported part 40Ab insertion part 40Ac Tsubabe 40Ad Undercut 40Ap Pinion 40B Gear 40Ba Insertion hole 40C Pinion 40D Crimping parts 40E Spacer M1 1st Mark M2 2nd Mark M3 3rd Mark T1 Needle position detection hole W Silicon Wafer L center line

Claims

1. A shaft, A silicon gear inserted into the shaft; a crimping member for crimping the gear to the shaft; A gear assembly equipped with:

2. A silicon pinion having a smaller diameter than the gear and inserted onto the shaft is provided, The crimping member crimps the pinion to the shaft. The gear assembly according to claim 1 .

3. The gear has a mark for aligning with the pinion in a circumferential direction, the mark is formed at a position that is covered by the teeth of the pinion when the pinion is assembled in a proper circumferential direction, and is exposed between the teeth of the pinion when the pinion is not assembled in a proper circumferential direction. The gear assembly according to claim 2.

4. The gear is formed with a hole for detecting the needle position. The gear assembly according to claim 3.

5. The hole for detecting the needle position also serves as the mark. The gear assembly according to claim 4.

6. The shaft has a relief groove at a corner on an inner diameter side of a surface that contacts the gear. The gear assembly according to claim 1 .

7. A silicon spacer is provided which is inserted into the shaft, The crimping member crimps the spacer to the shaft. The gear assembly according to claim 1 .

8. The shaft has a relief groove at an inner diameter side corner of a surface that contacts the spacer. The gear assembly according to claim 7.

9. A gear train mechanism including the gear assembly according to any one of claims 1 to 8; a case that houses the gear train mechanism; A watch equipped with.

10. A manufacturing method of a gear assembly including a gear for use in a train wheel mechanism of a timepiece and a pinion having a smaller diameter than the gear, comprising the steps of: an assembly process of assembling the gear assembly by inserting a shaft through the gear and the pinion, which are fabricated from a single silicon wafer by photolithography; Equipped with A manufacturing method for a gear assembly.

11. In the assembly process, the gear assembly is assembled by inserting the shaft through the gear and the pinion, which are fabricated by photolithography from the single silicon wafer, and the gear or the pinion having a larger diameter is positioned closer to a center line. A method for manufacturing the gear assembly according to claim 10.

12. The gear assembly further includes a spacer that adjusts positions of the gear and the pinion, In the assembling step, a shaft is inserted through the gear, the pinion, and the spacer, which are fabricated from the single silicon wafer by photolithography, to assemble the gear assembly. A method for manufacturing the gear assembly according to claim 10.

13. In the assembly process, the shaft is inserted through the gear and the pinion such that a mark of the gear is covered by the teeth of the pinion when the pinion is assembled in a proper circumferential direction, and a mark for aligning the circumferential direction with the pinion is formed at a position exposed between the teeth of the pinion when the pinion is not assembled in a proper circumferential direction, and the mark is covered by the teeth of the pinion. A method for manufacturing the gear assembly according to claim 10.

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