Gear assembly, timepiece, and method for manufacturing gear assembly

Abstract

A gear assembly is characterized by being provided with: a shaft body; a spur gear which is made of silicon and through which the shaft body is inserted; and a caulking member that caulks the spur gear to the shaft body.

Description

Technical Field

[0001] The present disclosure relates to a gear assembly, a timepiece, and a method for manufacturing the gear assembly. Background Art

[0002] In a gear train mechanism of a watch, for example, as disclosed in Japanese Patent Application Laid-Open No. 2020-30092, many gears of different shapes or sizes are used. In particular, high-priced products are often produced in small quantities and in a variety of varieties, so the manufacturing cost including development cost is likely to be high. Summary of the invention

[0003] A gear assembly according to one aspect of the present disclosure is characterized by comprising:

[0004] Axis body;

[0005] a spur gear made of silicon and through which the shaft is inserted; and

[0006] A riveting member is used to rivet the spur gear to the shaft body.

[0007] Another aspect of the present disclosure is characterized in that a timepiece includes:

[0008] A gear train mechanism including a gear assembly including a shaft body, a spur gear made of silicon and inserted through the shaft body, and a rivet member for riveting the spur gear to the shaft body; and

[0009] A housing accommodates the gear train mechanism.

[0010] A method for manufacturing a gear assembly according to another aspect of the present disclosure is

[0011] A method for manufacturing a gear assembly including a gear for use in a wheel train mechanism of a timepiece and a pinion having a diameter smaller than that of the gear, characterized by comprising:

[0012] The gear assembly is assembled by inserting a shaft into the gear and the pinion gear produced from a single silicon wafer by photolithography.

[0013] Further features of the present invention will become apparent from the following description of exemplary embodiments (with reference to the attached drawings). BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a front view showing the main part of the timepiece according to the embodiment.

[0015] Figure 2 It is a cross-sectional view of a wheel train mechanism of an hour hand driving mechanism in the timepiece according to the embodiment.

[0016] Figure 3It is a cross-sectional view of an example of a gear assembly according to the embodiment.

[0017] Figure 4 It is a cross-sectional view of an example of a gear assembly according to the embodiment.

[0018] Figure 5 1 is a top view of the gear involved in the implementation mode, wherein (a) is a single-body view, (b) is a view showing a state in which the circumferential orientation of the shaft body and the pinion gear is appropriate, and (c) is a view showing a state in which the circumferential orientation of the shaft body and the pinion gear is deviated.

[0019] Figure 6 This is a flowchart showing the procedure of the method for manufacturing the timepiece according to the embodiment.

[0020] Figure 7 FIG. 1 is a diagram showing an example of a silicon wafer on which the shapes of a plurality of gears and pinions are transferred by photolithography. DETAILED DESCRIPTION

[0021] An embodiment of the present invention will be described with reference to the drawings.

[0022] In addition, in the embodiment described below, various limitations that are technically preferable for carrying out the present invention are given, but the scope of the present invention is not limited to the following embodiment and the illustrated examples.

[0023] [Overall structure of the watch]

[0024] Figure 1 1 is a front view showing the main parts of the timepiece 100 according to the present embodiment. Figure 1 In order to facilitate understanding of the structure of the main parts, the illustration of a dial or a part of the main board 21 is omitted.

[0025] like Figure 1 As shown, the timepiece 100 according to the present embodiment is an analog timepiece that displays time using a plurality of hands 3 (second hand 3s, minute hand 3m, hour hand 3h) indicating a time scale 102. The timepiece 100 includes a main body case 101 formed in a short cylindrical shape when viewed from the front.

[0026] A plurality of hands 3 , a plurality of drive mechanisms 30 for individually driving the plurality of hands 3 to rotate, and the like are accommodated inside the main body case 101 .

[0027] The plurality of drive mechanisms 30 include a second hand drive mechanism 30s that rotationally drives the second hand 3s, a minute hand drive mechanism 30m that rotationally drives the minute hand 3m, and an hour hand drive mechanism 30h that rotationally drives the hour hand 3h.

[0028] Each driving mechanism 30 includes a motor 32 as a driving source and a wheel train mechanism 33 that transmits the driving force of the motor 32 to the hands 3. Specifically, the second hand driving mechanism 30s includes a first motor 32s and a first wheel train mechanism 33s, the minute hand driving mechanism 30m includes a second motor 32m and a second wheel train mechanism 33m, and the hour hand driving mechanism 30h includes a third motor 32h and a third wheel train mechanism 33h.

[0029] Each gear train mechanism 33 includes a plurality of gear assemblies 40 .

[0030] For example, the first wheel train mechanism 33s of the second hand drive mechanism 30s includes a gear assembly 40 such as the fourth wheel (second hand wheel). The second wheel train mechanism 33m of the minute hand drive mechanism 30m includes a gear assembly 40 such as the second wheel (minute hand wheel). The third wheel train mechanism 33h of the hour hand drive mechanism 30h includes a gear assembly 40 such as the intermediate wheel or barrel wheel (hour hand wheel).

[0031] In addition, the gear train mechanism 33 may include gears other than the gear assembly 40. The gear in this case only needs to include at least a gear and a shaft. The gear and the shaft may be separate components, or they may be integrated.

[0032] [Gear assembly configuration]

[0033] Hereinafter, as an example of the gear assembly 40 according to the present embodiment, the configuration of the gear assembly of the third wheel train mechanism 33h of the hour hand drive mechanism 30h will be described.

[0034] Figure 2 It is a cross-sectional view of the third wheel train mechanism 33 h in the timepiece 100 .

[0035] As shown in the figure, the third wheel train mechanism 33 h includes a first hour intermediate wheel 51 , a second hour intermediate wheel 52 , and a minute wheel 53 as the gear assembly 40 .

[0036] Each of these gear assemblies 40 includes: a shaft body 40A as a rotating shaft, a gear 40B for transmitting torque, a pinion 40C having a smaller diameter than the gear 40B, a rivet member 40D for fixing other components to the shaft body 40A, and a spacer 40E for adjusting the axial position of the gear 40B and the pinion 40C. However, the gear assembly involved in the present invention only needs to include at least a shaft body, a gear, and a rivet member. In addition to the shaft body, there may be multiple.

[0037] In addition, the components of the gear assembly 40 are identified by marking "A" at the end of the reference numeral of the shaft, "B" at the end of the reference numeral of the gear, "C" at the end of the reference numeral of the pinion, "D" at the end of the reference numeral of the riveted component, and "E" at the end of the reference numeral of the spacer (for example, the reference numeral of the shaft of the first hour intermediate wheel 51 is "51A").

[0038] Hereinafter, the front-back direction of the timepiece 100 is referred to as the up-down direction, wherein the front side ( Figure 2 The lower side) is called the "lower side", and the back side ( Figure 2 The upper side of the ) is called the “upper side”.

[0039] In the third wheel train mechanism 33h, the rotational force of the third motor 32h is transmitted to the first hour intermediate wheel 51, the second hour intermediate wheel 52, the minute wheel 53, and the barrel wheel 54 in sequence, so that the hour hand 3h rotates.

[0040] The first hour intermediate wheel 51 includes a shaft 51A, a gear 51B, a pinion 51C, a rivet member 51D, and a plurality of spacers 51E. The shaft 51A is rotatably supported at both ends by the main plate (bottom plate) 21 and the train wheel support 22. The train wheel support 22 is disposed on the upper side of the main plate 21 and supports the upper end of the shaft 51A. The gear 51B meshes with the rotor 51e of the third motor 32h. The pinion 51C is connected to the second hour intermediate wheel 52.

[0041] The details of the components of the gear assembly 40 will be described later.

[0042] The second hour intermediate wheel 52 has a shaft 52A, a gear 52B, a pinion 52C, a rivet member 52D, and a plurality of spacers 52E. The shaft 52A is rotatably supported at both ends by the train wheel support 22 and the date wheel pressing member 24. The date wheel pressing member 24 is arranged at a lower side than 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 step wheel 53.

[0043] The intermediate wheel 53 includes 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 wheel pressing member 24. The gear 53B meshes with the pinion 52C of the second hour intermediate wheel 52. The pinion 53C is connected to the barrel wheel 54.

[0044] The drum wheel 54 includes: a drum wheel body 54a, which is cylindrical and has the hour hand 3h fixed at the lower end; and a drum gear 54b, which is formed integrally with the drum wheel body 54a and meshes with the pinion 53C of the minute wheel 53. Thus, the rotational force of the third motor 32h is transmitted to the drum wheel 54 via the first hour intermediate wheel 51, the second hour intermediate wheel 52, and the minute wheel 53, so that the hour hand 3h at the lower end of the drum wheel body 54a rotates.

[0045] The center wheel & pinion 61 and the center wheel & pinion 71 are inserted into the inner side of the barrel wheel 54 , and the center wheel & pinion 61 and the center wheel & pinion 71 are coaxially arranged.

[0046] The second wheel 61 has a cylindrical second wheel body 61a and a second gear 61b. The second wheel body 61a is supported to be able to rotate independently of the barrel wheel 54 and the fourth wheel 71, and a minute hand 3m is fixed at the lower end. The second gear 61b is fixed to the upper end of the second wheel 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 second wheel 61, and the minute hand 3m at the lower end of the second wheel body 61a rotates.

[0047] The fourth wheel 71 has an axial fourth wheel body 71a and a fourth gear 71b. The fourth wheel body 71a is inserted into the second wheel body 61a, supported to be able to rotate independently of the barrel wheel 54 and the second wheel 61, and a second hand 3s is fixed at the lower end. The fourth gear 71b is fixed to the upper end of the fourth wheel 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 fourth wheel 71, and the second hand 3s at the lower end of the fourth wheel body 71a rotates.

[0048] Hereinafter, each component of the gear assembly 40 will be described in detail.

[0049] Figure 3 and Figure 4 is a cross-sectional view of an example of the gear assembly 40 .

[0050] <Axis>

[0051] like Figure 3 As shown, the shaft body 40A is a shaft member made of, for example, a carbon tool steel material (SK material), and has a supported portion 40Aa, an insertion portion 40Ab, and a flange portion 40Ac.

[0052] The supported portion 40Aa is a portion that is rotatably supported and is provided at both ends of the axial direction, for example.

[0053] The insertion portion 40Ab is a portion that is inserted through the gear 40B, the pinion 40C, the caulking member 40D, and the spacer 40E. The insertion portion 40Ab is formed to have a cross-section that is, for example, a polygonal shape (in Figure 3 and Figure 4In the example, the shape is hexagonal). In the center of the gear 40B, the pinion 40C, the rivet member 40D, and the spacer 40E, there are respectively provided insertion holes having a shape substantially the same as the cross-section of the insertion portion 40Ab. Figure 5 In FIG. 1 , the insertion hole 40Ba of the gear 40B is shown as an example.

[0054] The flange portion 40Ac is disposed, for example, at an axial end portion of the insertion portion 40Ab. The flange portion 40Ac abuts against the gear 40B, the pinion 40C, or the spacer 40E through which the insertion portion 40Ab is inserted in the axial direction for positioning.

[0055] A concave escape groove 40Ad is formed on the inner diameter side of the corner portion of the flange portion 40Ac that contacts the gear 40B or the spacer 40E, that is, the boundary portion between the insertion portion 40Ab in the shaft body 40A and the flange portion 40Ac having a larger diameter than the insertion portion 40Ab. That is, the concave escape groove 40Ad is provided by forming the shaft body 40A to have a smaller diameter than the insertion portion 40Ab. However, the escape groove 40Ad may be any shape as long as it can escape (avoid contact) with the inner diameter side corner portion of the gear 40B, the pinion 40C or the spacer 40E.

[0056] In addition, if Figure 4 As shown, the shaft body 40A may also have a pinion 40Ap integrally. 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 addition, in this case, an avoidance groove 40Ad may be provided at the corner portion on the inner diameter side of the pinion 40Ap.

[0057] In the gear train mechanism 33, a plurality of shaft bodies 40A are supported by several common components (base plates). For example, in the case of the third gear train mechanism 33h, Figure 2 As shown, each shaft body 40A is supported by any two members of the main board 21, the wheel train support 22, and the date wheel pressing member 24. Therefore, based only on the length in the up-down direction (axial direction), the shaft body 40A can be roughly divided into a shaft body from the wheel train support 22 to the main board 21, a shaft body from the wheel train support 22 to the date wheel pressing member 24, and a shaft body from the main board 21 to the date wheel pressing member 24. That is, by using a plurality of gear assemblies 40 that have a common substrate for support, the shaft body 40A can be shared. In addition, if the substrate for support (or its axial position) is common, the shaft body 40A can of course also be shared with other wheel train mechanisms 33.

[0058] <Gears and Pinions>

[0059] Figure 51 and 10 are top views of the gear 40B, wherein (a) is a single-body view, (b) is a view showing a state in which the circumferential orientation of the shaft body 40A and the pinion gear 40Ap is appropriate, and (c) is a view showing a state in which the circumferential orientation of the shaft body 40A and the pinion gear 40Ap is deviated.

[0060] like Figure 5 As shown in (a) and (b), the gear 40B and the pinion 40C are both spur gears made of silicon, for example, and the pinion 40C is a gear having a smaller diameter than the gear 40B. As described later, the gear 40B and the pinion 40C of this embodiment are manufactured from a silicon wafer by photolithography.

[0061] An insertion hole 40Ba through which the shaft body 40A is inserted is formed at the center of the gear 40B. The insertion hole 40Ba is formed in a polygonal shape corresponding to the insertion portion 40Ab of the shaft body 40A.

[0062] A needle position detection hole T1 penetrating in the thickness direction is formed at a predetermined position on the outer circumferential side of the gear 40B. Among the needle position detection holes T1, the needle position detection holes T1 formed in a plurality of gears 40B stacked up and down overlap at a predetermined timing (cycle) when the needle moves. At this time, the light of the light emitting unit is transmitted through the overlapping needle position detection holes T1 in the plurality of gears 40B and is detected by the light receiving unit, thereby detecting the position of the pointer 3.

[0063] A first mark M1 for discriminating the type of gear is formed around the insertion hole 40Ba in the gear 40B. The hole shape, number, position, etc. of the first mark M1 differ depending on the type of the gear 40B, for example.

[0064] The gear 40B is provided with a second mark M2 for direction determination. However, in the gear 40B having the hand position detection hole T1 formed therein, the hand position detection hole T1 may be used for direction determination without providing the second mark M2.

[0065] In addition, the positions, numbers, shapes, etc. of the first mark M1 and the second mark M2 are not particularly limited. However, when they are arranged near the needle position detection hole T1, light passing through the first mark M1 and the second mark M2 may cause erroneous detection. Therefore, the first mark M1 and the second mark M2 are preferably formed near the insertion hole 40Ba.

[0066] In addition, the gear 40B is formed with a third mark M3 for aligning the circumferential direction with the pinion 40C (or the pinion 40Ap).

[0067] The third mark M3 is formed at the position of the teeth (peaks) of the pinion 40C when the pinion 40C is assembled in the appropriate circumferential direction in the gear 40B. Figure 5As shown in (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. Figure 5 As shown in (c), for example, when the circumferential direction of the pinion 40C deviates from the proper position by one pitch of the insertion hole 40Ba, the third mark M3 is exposed from the valley of the pinion 40C. Thus, the assembler (or inspector) can easily determine whether the gear 40B and the pinion 40C are properly assembled based on whether the third mark M3 is exposed from the pinion 40C.

[0068] In addition, the needle position detection hole T1 may also serve as (the function of) the third mark M3.

[0069] In addition, it is preferable that the first mark M1, the second mark M2, and the third mark M3 are formed as small as possible so that the strength of the gear 40B is not excessively reduced. For example, when the gear 40B is made using a photoresist mask, it is preferable to set the limit of the processing accuracy, that is, However, it is necessary that the dimensions be such that the operator can visually confirm the dimensions during assembly.

[0070] The gear 40B and the pinion 40C are fixed to the shaft body 40A integrally (or separately) with other components by a rivet member 40D. Alternatively, the gear 40B and the pinion 40C may be fixed to the shaft body 40A by an adhesive. In this case, the avoidance groove 40Ad of the shaft body 40A can be used as a storage groove for the adhesive, and the excess part of the adhesive can be suppressed from overflowing. 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 body 40A by press-fitting.

[0071] In addition, the pinion gear 40C may be divided into a plurality of parts in the axial direction. That is, a plurality of pinion gears 40C may be overlapped in the axial direction to increase the thickness.

[0072] <Riveted components>

[0073] like Figure 3 and Figure 4 As shown, the caulking member 40D is press-fitted into the shaft body 40A to caulk (fasten) the gear 40B, the pinion 40C, and the spacer 40E to the shaft body 40A and fix them. The caulking member 40D is formed in a short annular shape with a thickness of about 0.1 mm, for example.

[0074] The material (raw material) of the caulking member 40D is not particularly limited as long as it can be press-fitted into the shaft body 40A, and is, for example, nickel.

[0075] In addition, when the gear 40B or the pinion 40C is fixed to the shaft body 40A by press-fitting, the caulking member 40D may be omitted.

[0076] <Spacer>

[0077] The spacer 40E is formed into a cylindrical shape and is inserted through the shaft body 40A to adjust the axial position 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 to allow one shaft body 40A to pass through.

[0078] When the spacer 40E is disposed between the gear 40B and the pinion 40C, the size of the spacer 40E is preferably set to be smaller than the diameter of the root circle of the gear 40B and the pinion 40C. Thus, the height of the pinion 40C can be freely adjusted to the optimum height as required while ensuring the clearance in the height direction between the gears 40B that are linked to each other.

[0079] The material (raw material) of the spacer 40E is not particularly limited, and may be silicon, nickel, or brass, etc. For example, if the spacer 40E is made of silicon by photolithography, the smoothness of the end surface is high, so that tilting can be suppressed even when a plurality of spacers are overlapped.

[0080] [Manufacturing method]

[0081] Figure 6 is a flowchart showing the sequence of a method for manufacturing a timepiece 100 including a gear assembly 40, Figure 7 1 is a diagram showing an example of a silicon wafer W on which the shapes of a plurality of gears 40B and pinions 40C are transferred by photolithography.

[0082] like Figure 6 As shown, in the method for manufacturing the timepiece 100 , first, the gear 40B and the pinion 40C are manufactured by photolithography (step S1 ).

[0083] like Figure 7 As shown, in this step, various gears 40B and pinions 40C used for one timepiece 100 are manufactured from one silicon wafer W. The thickness of the silicon wafer W is about 0.1 to 0.15 mm.

[0084] At this time, the gear 40B and the pinion 40C are arranged (arranged) so that the larger the diameter, the closer they are to the center line L that roughly divides the silicon wafer W into two parts. In addition, the width of each row of the gear 40B and the pinion 40C (the length in the direction perpendicular to the center line L) is made as constant as possible along the center line L. In this way, the gear 40B and the pinion 40C can be arranged in a manner that does not easily generate wasteful excess space on the roughly circular silicon wafer W. However, the arrangement of the gear 40B and the pinion 40C on the silicon wafer W can also be appropriately adjusted so that the excess space on the silicon wafer W is as small as possible.

[0085] Alternatively, the spacer 40E may be manufactured from the same silicon wafer W together with the gear 40B and the pinion 40C.

[0086] Then, if Figure 6 As shown, each gear assembly 40 is assembled (step S2).

[0087] Here, after the shaft body 40A is inserted through the gear 40B, the pinion 40C and the spacer 40E, the caulking member 40D is pressed in with the gear 40B, the pinion 40C and the spacer 40E interposed between the caulking member 40D and the flange portion 40Ac, and the caulking member 40D is assembled. Figure 3 The gear assembly 40 is shown.

[0088] Alternatively, after the shaft 40A is inserted through the gear 40B and the spacer 40E, the caulking member 40D is pressed in with the gear 40B and the spacer 40E interposed between the caulking member 40D and the pinion 40C, and the assembly is performed. Figure 4 The gear assembly 40 is shown.

[0089] At this time, the assembling operator checks the first mark M1 of the gear 40B to identify the type thereof, and combines it with the corresponding shaft body 40A or pinion gear 40C or the like.

[0090] 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). Thus, the gear 40B and the pinion 40C (or the pinion 40Ap) can be assembled in an appropriate circumferential orientation.

[0091] Next, the entire timepiece 100 is assembled (step S3).

[0092] Here, a module including a gear train mechanism 33 formed by a plurality of gear assemblies 40 assembled in step S3, a pointer 3, etc. is installed in the main body case 101. Furthermore, as required, for example, in the case of an electronic timepiece, a timing circuit, a battery pack, etc. are installed, and in the case of a mechanical timepiece, an escape wheel, a hairspring, etc. are installed.

[0093] The timepiece 100 is assembled in this way.

[0094] [Technical Effects of the Present Embodiment]

[0095] As described above, according to the present embodiment, the gear assembly 40 includes the shaft body 40A, the gear 40B made of silicon, and the rivet member 40D for riveting the gear 40B to the shaft body 40A. In the case of using a gear made of metal, since the structure becomes complicated, the rivet member is not used, but the inner diameter of the gear made of metal is formed to be slightly smaller than the outer shape of the shaft body, and the gear is riveted to the shaft body by press-fitting. On the other hand, in the case of the gear 40B made of silicon, since the gear 40B is a hard material, the gear cannot be riveted to the shaft body by press-fitting, but by using the rivet member 40D, the gear 40B can be riveted to the shaft body 40A even if it is made of silicon. Thus, the gear 40B made of silicon can be used.

[0096] In addition, by adopting the above-mentioned structure, a plurality of gear assemblies 40 of different types can be used, and the shaft 40A can be made common by simply replacing the gear 40B, etc. Therefore, even for a small number of products with many varieties, the development period and development cost can be reduced. Furthermore, the manufacturing cost including the development cost can be reduced.

[0097] In addition, by using the gear 40B made of silicon, it is harder and has a higher surface smoothness than a gear made of metal or resin, so it is possible to reduce friction, thereby suppressing the power consumption (energy consumption) when the needle is running. In particular, since the power consumption of driving the second hand 3s is greater than that of other hands 3, the effect of applying it to the second hand drive mechanism 30s is large. In addition, by reducing the friction of the gear 40B, it is possible to achieve low backlash, which can improve the position accuracy of the pointer 3.

[0098] According to the present embodiment, the gear assembly 40 includes a silicon pinion 40C having a smaller diameter than the gear 40B, and the caulking member 40D caulks the pinion 40C to the shaft 40A. That is, the pinion 40C can be separated from the shaft 40A.

[0099] This can reduce the number of pinion shafts that require development costs, and further reduce manufacturing costs including development costs.

[0100] In addition, according to the present embodiment, the gear 40B has a third mark M3 for aligning the circumferential direction with the pinion 40C. The third mark M3 is formed at a position where it is covered by the teeth of the pinion 40C when the pinion 40C is assembled in the proper circumferential direction, and is exposed from between the teeth of the pinion 40C when the pinion 40C is not assembled in the proper circumferential direction.

[0101] Thus, the assembling operator can easily determine whether the gear 40B and the pinion 40C are assembled in an appropriate circumferential orientation (relative rotation angle) by checking whether the third mark M3 is exposed from the pinion 40C.

[0102] When detecting the position of the pointer 3, the needle position detection holes T1 of the plurality of gears 40B are rotated and moved to a position where they overlap each other, and the position of the pointer 3 is detected based on the amount of light transmitted through the plurality of needle position detection holes T1. Here, if the gear 40B and the pinion 40C are assembled in an appropriate circumferential orientation, the needle position detection holes T1 will also be assembled in an appropriate circumferential orientation, and therefore, when further detecting the position of the pointer 3, the plurality of needle position detection holes T1 will overlap as expected, so that the amount of light transmitted through the needle position detection holes T1 can be maximized. Thus, the position of the pointer 3 can be detected with high accuracy. On the contrary, when the gear 40B and the pinion 40C are not assembled in an appropriate circumferential orientation, the needle position detection holes T1 will not be assembled in an appropriate circumferential orientation, and as a result, the position of the pointer 3 cannot be accurately detected.

[0103] Furthermore, according to the present embodiment, the gear assembly 40 includes the spacer 40E through which the shaft body 40A is inserted.

[0104] Thus, the shaft body 40A can be used in common by the plurality of gear assemblies 40 , and the height (axial position) of the gear 40B or the pinion 40C can be adjusted individually by the spacer 40E.

[0105] Furthermore, according to the present embodiment, the shaft body 40A has the escape groove 40Ad at the corner portion on the inner diameter side of the surface of the flange portion 40Ac that contacts the gear 40B.

[0106] This can suppress the chipping of the corner portion caused by the contact between the corner portion on the inner diameter side of the gear 40B and the corner portion on the inner diameter side of the flange portion 40Ac of the shaft body 40A.

[0107] That is, the gear 40B made of silicon is very hard, and is also made by photolithography, so when stress is concentrated, not only is the corner easily damaged, but it is also difficult to chamfer the corner. Therefore, it is not desirable to form an angle R on the inner diameter side of the flange portion 40Ac that may interfere with (contact) the gear 40B during installation. However, when the flange portion 40Ac is formed by conventional cutting, it is unavoidable to form an angle R on the inner diameter side of the flange portion 40Ac. Therefore, the angle R is removed by performing additional cutting in the radial direction (inner diameter direction) on the inner diameter side of the flange portion 40Ac, and an avoidance groove 40Ad having a diameter smaller than the diameter of the insertion portion 40Ab is provided on the shaft body 40A. Thus, interference between the shaft body 40A and the gear 40B during installation can be avoided. Thus, the positioning of the gear 40B does not become difficult due to reducing the gear 40B to avoid the angle R, and the gear 40B can be properly assembled to the shaft body 40A. That is, the gear 40B can be positioned with high accuracy both in the axial direction and in the radial direction.

[0108] In addition, the processing direction of the avoidance groove 40Ad is preferably radial (toward the inner diameter). When the avoidance groove 40Ad is to be processed in the axial direction, a hexagonal undercut corresponding to the shape of the insertion portion 40Ab is required. On the other hand, by setting the processing direction of the avoidance groove 40Ad to the radial direction (toward the inner diameter), the avoidance groove 40Ad can be formed relatively easily by cutting.

[0109] In addition, when the gear 40B is joined to the shaft 40A by an adhesive, the escape groove 40Ad can be used as a reservoir for the adhesive. This can prevent the excess adhesive from overflowing from the gap between the shaft 40A and the gear 40B or the escape groove 40Ad. Furthermore, the occurrence of malfunction caused by the overflowing adhesive can be prevented.

[0110] According to the present embodiment, the various gears 40B and the pinion gears 40C are manufactured from one silicon wafer W by photolithography.

[0111] Thus, the shaft 40A can be shared by using a plurality of gear assemblies 40, and a variety of gears 40B and pinions 40C can be appropriately manufactured. Therefore, even for a small number of products with a variety of products, the development period and development cost can be reduced. Furthermore, the manufacturing cost including the development cost can be reduced.

[0112] In addition, since a plurality of gears 40B and pinions 40C are produced from one silicon wafer W by photolithography, these components can be formed to have the same thickness dimension (length in the vertical direction). Moreover, the main surface of the silicon wafer W (the surface with the thickness direction of the silicon wafer W as the normal line) has high smoothness. Thus, even if a plurality of any one or more of the gears 40B, pinions 40C, rivet members 40D, and spacers 40E are stacked, the gear assembly 40 can be formed in a manner that the thickness dimension after stacking reaches the desired level with high accuracy.

[0113] Therefore, even when the third wheel train mechanism 33h is manufactured by combining the first hour intermediate wheel 51, the second hour intermediate wheel 52 and the minute wheel 53 as in the present embodiment, the heights (the positions in the vertical direction) of the mutually meshing wheels among the first hour intermediate wheel 51, the second hour intermediate wheel 52 and the minute wheel 53 can be set with high precision.

[0114] Furthermore, since the main surfaces (surfaces with the vertical direction as the normal direction) of the gear 40B, the pinion 40C, the caulking member 40D, and the spacer 40E are highly smooth, the loss of kinetic energy due to friction between the main surfaces is also suppressed to a very low level.

[0115] In addition, according to the present embodiment, a plurality of gears 40B and pinions 40C are arranged on one silicon wafer W in such a manner that gears 40B and pinions 40C having larger diameters are located closer to the center line L of the silicon wafer W. In this case, gears 40B and pinions 40C having the same diameter are arranged in a direction parallel to the center line L of the silicon wafer W.

[0116] Thus, the plurality of gears 40B and the pinion gears 40C can be appropriately arranged on the silicon wafer W, and wasteful excess space on the silicon wafer W can be reduced. Therefore, the manufacturing cost can be further suppressed.

[0117] Furthermore, according to the present embodiment, the spacer 40E is manufactured from the same silicon wafer W together with the gear 40B and the pinion 40C.

[0118] This can further reduce the manufacturing cost.

[0119] [other]

[0120] In addition, the embodiment to which the present invention can be applied is not limited to the above-mentioned embodiment, and various modifications can be made without departing from the scope of the present invention.

[0121] For example, in the above-mentioned embodiment, the gear and the pinion (or further the spacer) are made of silicon having a lattice plane and are made by photolithography. However, the material (raw material) of the gear and the pinion (or further the spacer) is not limited to silicon, and the manufacturing method is not limited to photolithography.

[0122] For example, a wafer made of diamond can be used as a material having a lattice plane. Furthermore, it can be made of nickel or brass by electroforming. Even in the case of being made by electroforming, the thickness is the same as that of a silicon wafer. In this case, the gear and the pinion can be pressed into the shaft, so the riveting member can be omitted. However, since nickel is a magnetic body, the gear that meshes with the motor is not applied to the pinion.

[0123] Furthermore, the gear assembly of the present invention is not limited to the gear assembly used in the wheel train mechanism of a clock, but can be widely applied to a gear assembly in which a shaft is inserted through a gear, and can be particularly applied to a small gear mechanism in which it is difficult to adopt a complicated bearing structure.

[0124] While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

[0125] This application claims the benefit of Japanese Patent Application No. 2023-159312, filed on September 25, 2023, which is hereby incorporated by reference herein in its entirety.

Claims

1. A gear assembly, characterized in that: have: Axis body; a spur gear made of silicon and through which the shaft is inserted; and A riveting member is used to rivet the spur gear to the shaft body.

2. The gear assembly according to claim 1, wherein: The spur gear includes a gear through which the shaft body is inserted and / or a pinion through which the shaft body is inserted. The rivet member rivets the gear and / or the pinion to the shaft body.

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

4. The gear assembly according to claim 3, wherein: A hole for detecting the needle position is formed in the gear. The hole for needle position detection also serves as the mark.

5. The gear assembly according to claim 2, wherein: The shaft body has a flange portion having a diameter larger than a diameter of the insertion portion of the shaft body, The shaft body has a relief groove at a corner portion on the inner diameter side of a surface of the flange portion that contacts the gear.

6. The gear assembly according to claim 1, wherein: A spacer made of silicon is provided through which the shaft is inserted, The shaft body has a flange portion having a diameter larger than a diameter of the insertion portion of the shaft body, The shaft body has an escape groove at a corner portion on the inner diameter side of a surface of the flange portion that contacts the spacer.

7. The gear assembly according to claim 1, wherein: The spur gear includes a gear through which the shaft body is inserted. The shaft body integrally has a pinion with a diameter smaller than that of the gear. The shaft body has a relief groove at a corner portion on the inner diameter side of a surface of the pinion gear that contacts the gear.

8. A timepiece, characterized in that: have: A gear train mechanism comprising the gear assembly according to any one of claims 1 to 7; and A housing accommodates the gear train mechanism.

9. A method for manufacturing a gear assembly, comprising a gear for a wheel train mechanism of a timepiece and a pinion having a diameter smaller than that of the gear, characterized in that: have: The gear assembly is assembled by inserting a shaft into the gear and the pinion gear produced from a single silicon wafer by photolithography.

10. The method for manufacturing a gear assembly according to claim 9, wherein: In the assembling step, the gear assembly is assembled by inserting the shaft through the gear and the pinion which are fabricated from the one silicon wafer by photolithography and are arranged so that the gear or the pinion with a larger diameter is located closer to the center line.

11. The method for manufacturing a gear assembly according to claim 9, wherein: The gear assembly further comprises a spacer for adjusting the position of the gear and the pinion. In the assembling step, the gear assembly is assembled by inserting a shaft through the gear, the pinion, and the spacer that are manufactured from the one silicon wafer by photolithography.

12. The method for manufacturing a gear assembly according to claim 9, wherein: In the assembly process, the shaft is inserted into the gear and the pinion in such a manner that a mark on the gear for aligning the circumferential orientation with the pinion is covered by the teeth of the pinion, and the mark is formed at a position in the gear where it is covered by the teeth of the pinion when the pinion is assembled in the proper circumferential orientation, and is exposed from between the teeth of the pinion when the pinion is not assembled in the proper circumferential orientation.

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