Method for designing c-shaped bangle
Patent Information
- Application Number
- PCT/JP2025/036896
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-03-10
- Filing Date
- 2025-10-20
- Publication Date
- 2026-09-17
Smart Images
Figure JP2025036896_17092026_PF_FP_ABST
Abstract
Description
Method for designing a C-shaped bangle
[0001] The present invention relates to a method for designing a C-shaped bangle.
[0002] Hitherto, bracelets and bangles that can be adapted to the size of each user's wrist have been proposed.
[0003] For example, Patent Document 1 describes a bracelet clasp device comprising a clasp consisting of two relatively slidable elongated elements, a lockable sliding member and a fixing member.
[0004] Japanese National Publication of International Patent Application No. 2007-521892
[0005] Although the bracelet clasp device described in Patent Document 1 can adjust the length of the bracelet according to the size of the user's wrist, there is a problem in that when the user moves the wrist, a feeling of compression or the like caused by the bracelet portion occurs, and it is difficult to obtain comfort.
[0006] In view of such circumstances, an object of the present invention is to provide a method for designing a C-shaped bangle that is comfortable even when the user moves the wrist when the user wears the bangle on the wrist.
[0007] The present invention that solves the above problems is described in [1] to [6] below.
[0008] [1] A method for designing a metal C-shaped bangle, the metal C-shaped bangle having an upper band portion, a thumb-side arc portion, a little finger-side arc portion, a thumb-side end portion, a little finger-side end portion, and a gap portion between the thumb-side end portion and the little finger-side end portion, (A) a wrist measurement step of measuring the circumference of the user's wrist, the width of the wrist, the thickness of the wrist, the position of the user's palmaris longus tendon and / or flexor carpi radialis muscle, and the position of the abductor pollicis longus tendon in the thickness direction of the user's wrist, (B) a C-shaped bangle inner diameter determination step of determining the inner diameter of the C-shaped bangle based on the measured values of the user's wrist circumference, wrist width and wrist thickness, A method for designing a metal C-shaped bangle, comprising: (C) forming the gap portion based on the measured position of the palmaris longus tendon and / or flexor carpi radialis muscle such that when the user wears the C-shaped bangle, the position opposite the palmaris longus tendon and / or flexor carpi radialis muscle is near the center of the gap portion; and (D) forming the curve of the thumb-side arc portion based on the measured position of the abductor pollicis longus tendon such that when the user wears the C-shaped bangle, the curvature of the thumb-side arc portion is maximized.
[0009] [2] A preferred embodiment of the present invention is a method for designing a metal C-shaped bangle as described in [1], further comprising: (E) an end adjustment step of adjusting the thumb end and / or the little finger end, wherein step (E) includes adjusting the thumb end and / or the little finger end so that when the user puts the C-shaped bangle on their wrist and flexes their hand, the thumb end and / or the little finger end do not press against the inside of the user's wrist.
[0010] [3] A preferred embodiment of the present invention is a method for designing a metal C-shaped bangle according to [1] or [2], wherein step (D) includes the step of forming the curve of the thumb-side arc portion so that when the user puts the C-shaped bangle on their wrist and contracts the abductor pollicis longus tendon, the thumb-side arc portion does not compress the abductor pollicis longus tendon.
[0011] [4] A preferred embodiment of the present invention is a method for designing a metal C-shaped bangle according to any one of [1] to [3], wherein step (D) is a step of forming the curves of the thumb-side arc portion and / or the little-finger-side arc portion so that when the user puts the C-shaped bangle on their wrist and the user dorsiflexes their hand, the upper band portion does not compress the extensor tendons of the user's fingers.
[0012] [5] A preferred embodiment of the present invention is a method for designing a metal C-shaped bangle according to any one of [1] to [4], wherein step (D) is a step of forming the curves of the thumb-side arc and / or the little-finger-side arc so that when the user puts the C-shaped bangle on their wrist and the user flexes their hand, the thumb-side arc does not compress the abductor pollicis longus tendon.
[0013] [6] A preferred embodiment of the present invention is a method for designing a metal C-shaped bangle according to any one of [1] to [5], which includes processing the C-shaped bangle so that the contact surface with the user's wrist is curved.
[0014] According to the present invention, it is possible to provide a method for designing a C-shaped bangle that provides a comfortable fit even when the user moves their wrist while wearing the bangle on their wrist.
[0015] This is a diagram of a C-shaped bangle worn on the right wrist according to one embodiment of the present invention, a) front view from the user's side, b) rear view from the user's side, c) top view, d) bottom view, e) right side view, f) left side view, and g) cross-sectional view along A-A. This is a diagram of the design flow according to one embodiment of the design method for the C-shaped bangle of the present invention. This is a diagram of the design flow according to one embodiment of the curve forming process of the design method for the C-shaped bangle of the present invention. This is a diagram of the design flow according to one embodiment of the design method for the C-shaped bangle of the present invention. (a) This is a schematic diagram of the abductor pollicis longus tendon 51 when the user's right wrist 5, in which the abductor pollicis longus tendon 51 is located on the palm side with respect to the thickness direction of the wrist, is observed from the thumb side with the forearm horizontal (for example, with the forearm placed on a horizontal surface such as a desk). (b) This is a diagram of the lower part of the thumb-side arc 52 of the C-shaped bangle. (c) This is a schematic diagram showing the relationship between the lower part of the thumb-side arc 52 and the abductor pollicis longus tendon 51 when the user is wearing the C-shaped bangle. (a) A schematic diagram of the abductor pollicis longus tendon 51 when observed from the thumb side with the forearm horizontal (for example, with the forearm placed on a horizontal surface such as a desk), where the abductor pollicis longus tendon 51 is located near the center of the wrist in relation to the thickness direction of the wrist. (b) A diagram showing the thumb side arc center portion 62 of the C-shaped bangle. (c) A schematic diagram showing the relationship between the thumb side arc center portion 62 and the abductor pollicis longus tendon 51 when the user is wearing the C-shaped bangle. A schematic diagram from the palm side when the C-shaped bangle is worn on the right wrist. A diagram showing an example of the wrist measurement position in the wrist measurement step of the design method for the C-shaped bangle of the present invention.
[0016] Preferred embodiments of the present invention will be described below, but the technical scope of the present invention is not limited to the following embodiments.
[0017] <1> C-shaped bangle <1-1> The metal used for the raw material C-shaped bangle may be any of the following: precious metal, precious metal alloy, base metal, or base metal alloy. Among these, precious metal or precious metal alloy is preferred.
[0018] Examples of precious metals include pure gold, pure silver, and pure platinum.
[0019] Furthermore, a precious metal alloy is composed primarily of one type of precious metal, with the entire alloy further containing one or more other precious metals and / or one or more base metals.
[0020] Examples of base metals include germanium, bismuth, indium, copper, and palladium.
[0021] Furthermore, examples of precious metal alloys include gold alloys such as 9-karat, 10-karat, 14-karat, 18-karat, 20-karat, and 22-karat gold; platinum alloys such as Pt900 and Pt950; and silver alloys such as Silver 925 and Silver 950.
[0022] In designing a C-shaped bangle, the design may be made using the raw material metal, or the C-shaped bangle may be designed using a metal that is cheaper than the raw material, and then the C-shaped bangle may be manufactured using the raw material metal based on the design.
[0023] <1-2> Forming and Adjusting C-Shaped Bangles It is preferable to use a forging method for forming and adjusting metal C-shaped bangles. In the forging method, the C-shaped bangle may be formed and adjusted using the grip strength of the hand, or it may be formed and adjusted using tools used for metalworking.
[0024] Tools used in metalworking include iron tools, wooden tools, files, rolling mills, and disc grinders.
[0025] In this case, it is preferable to use a wooden mandrel and / or a wooden mallet as the wooden tools.
[0026] For forming and adjusting a metal C-shaped bangle, it is preferable to use the grip strength of the hand and a wooden tool. Using the grip strength of the hand and a wooden tool allows for adjustments in 1 mm increments.
[0027] Furthermore, using wooden tools allows for processing without damaging the metal.
[0028] <1-3> The contact surface with the user's wrist (A-A cross-section in Figure 1(g)) in any cross-section horizontal to the upper band portion of the C-shaped bangle can be a flat or curved surface, but it is preferable to process the C-shaped bangle so that the contact surface with the user's wrist is curved.
[0029] By processing the C-shaped bangle so that the contact surface with the user's wrist is curved, the pressure felt when the user moves their wrist while wearing the bangle can be minimized.
[0030] <1-4> Thickness (width) of the C-shaped bangle The thickness (width) of the C-shaped bangle is preferably 0.3 cm or more, more preferably 0.4 cm or more, and even more preferably 1 cm or more.
[0031] By setting the lower limit of the thickness of the C-shaped bangle within the above range, the risk of deformation and breakage is reduced, while ensuring sufficient strength.
[0032] The thickness of the C-shaped bangle is preferably 2.5 cm or less, more preferably 2 cm or less, and even more preferably 1.5 cm or less.
[0033] By setting the upper limit of the C-shaped bangle's thickness within the above range, the overall weight is reduced, making it less burdensome to wear for extended periods.
[0034] Furthermore, by setting the upper limit of the C-shaped bangle's thickness within the above range, the feeling of pressure on the user's wrist when they move their wrist while wearing the bangle can be minimized.
[0035] <2> Design Method for a C-Shaped Bangle The design method for a C-shaped bangle according to the present invention will be described in detail below with reference to Figures 2 and 3. Figures 2 and 3 are one embodiment of the design method for a C-shaped bangle, and the order and number of times each step is performed are not limited to the order shown in Figures 2 and 3, and the order of each step may be arbitrarily changed. In addition, each step does not have to be performed, may be performed once, or may be performed multiple times.
[0036] <2-1> Wrist measurement step The wrist measurement step S21 of the present invention will be described with reference to FIG. 5 and FIG. 6. The wrist measurement step S21 of the present invention measures the circumference of the user's wrist, the width of the wrist, the thickness of the wrist, the position of the user's palmaris longus tendon and / or flexor carpi radialis, and the position of the abductor pollicis longus tendon relative to the thickness direction of the user's wrist.
[0037] The wrist to be measured may be either the right wrist or the left wrist, but is preferably the wrist on which the C-shaped bangle is worn.
[0038] There is no particular limitation on the measurement site for the circumference of the user's wrist, but it is preferably the site where the C-shaped bangle is worn. In particular, it is preferably a site on the palmar side from the styloid process of ulna.
[0039] There is no particular limitation on the method for measuring the circumference of the user's wrist, and examples include a method such as wrapping a tape measure around the site where the C-shaped bangle is worn.
[0040] The width of the user's wrist refers to the length of the wrist in the left-right direction when the user looks at his or her palm.
[0041] There is no particular limitation on the measurement site for the width of the user's wrist, but it is preferably the site where the C-shaped bangle is worn.
[0042] The thickness of the user's wrist refers to the length in the direction from the palmar side to the dorsal side of the hand when the forearm is placed horizontally (for example, when the forearm is placed on a horizontal surface such as a desk).
[0043] There is no particular limitation on the measurement site for the thickness of the user's wrist, but it is preferably the site where the C-shaped bangle is worn. In particular, it is preferably a site on the palmar side from the styloid process of ulna.
[0044] There is no particular limitation on the method for measuring the thickness of the user's wrist, and examples include a method of performing measurement when the forearm is placed horizontally (for example, when the forearm is placed on a horizontal surface such as a desk).
[0045] As the measurement site for the position of the user's palmaris longus tendon and / or flexor carpi radialis, it is preferably the site where the C-shaped bangle is worn. In particular, it is preferably a site on the palmar side from the styloid process of ulna.
[0046] Here, the positions of the palmaris longus tendon and / or the flexor carpi radialis are measured to determine whether they are located near the center, on the thumb side of the center, or on the little finger side of the center, relative to the width of the wrist at the site where the C-shaped bangle is worn. The measurement may be performed directly with a measuring tape, or may be performed by capturing a photograph, measuring on the plane of the photograph with a measuring tape, or observing visually (the same applies to the following measurements).
[0047] As a measurement site for the position of the abductor pollicis longus tendon in the thickness direction of a user's wrist, the site where the C-shaped bangle is worn is preferable. In particular, a site on the palmar side relative to the ulnar styloid process is preferable.
[0048] There are no particular restrictions on the method for measuring the position of the abductor pollicis longus tendon in the thickness direction of the user's wrist, but it is desirable to measure the position of the abductor pollicis longus tendon while opening and closing the hand.
[0049] Here, the position of the abductor pollicis longus tendon refers to measurement, when the forearm is placed horizontally (for example, the forearm is placed on a horizontal surface such as a desk), of whether, with respect to the thickness direction of the wrist: (1) it is located on the palmar side (see FIG. 5(a)), or (2) it is located near the center of the wrist (see FIG. 6(a)).
[0050] The C-shaped bangle targeted by the design method of the present invention is preferably intended to be worn on the palmar side relative to the ulnar styloid process.
[0051] The design method of the present invention is suitable for a C-shaped bangle worn on the palmar side relative to the ulnar styloid process.
[0052] Furthermore, a C-shaped bangle worn on the palmar side relative to the ulnar styloid process is less likely to hinder the natural movement of the wrist, and can provide a comfortable wearing feel. In particular, it causes less discomfort even when worn for a long time or in situations where the hand is moved frequently, enabling comfortable use.
[0053] <2―2>C-shaped bangle inner diameter determining step Next, the C-shaped bangle inner diameter determining step S22 of the present invention will be described. The C-shaped bangle inner diameter determining step S22 of the present invention includes a step of determining the inner diameter of the C-shaped bangle based on measured values of the wrist circumference, wrist width, and wrist thickness of the user.
[0054] In the C-shaped bangle inner diameter determination step S22, it is preferable to make it the same as the circumference of the user's wrist.
[0055] Furthermore, the C-shaped bangle inner diameter determination step S22 includes the step of determining the width of the user's wrist as the major axis 17 of the C-shaped bangle.
[0056] Furthermore, the C-shaped bangle inner diameter determination step S22 includes a step of determining the thickness of the user's wrist as the C-shaped bangle's short diameter 18.
[0057] <2-3> Gap Formation Process Next, the gap formation process S23 of the present invention will be described. As shown in Figure 7, the gap formation process S23 of the present invention includes a gap formation process in which the gap 12 is formed based on the measured position of the palmaris longus tendon and / or flexor carpi radialis muscle of the user, such that when the user wears the C-shaped bangle, the position opposite to the palmaris longus tendon and / or flexor carpi radialis muscle is near the center of the gap 12.
[0058] When the user wears the C-shaped bangle, the position corresponding to the palmaris longus tendon and / or flexor carpi radialis muscle is near the center of the gap 12, thereby reducing discomfort caused by contact between the C-shaped bangle and the user's wrist when the user flexes their hand.
[0059] Furthermore, the size of the gap 12 is preferably 9 / 10 to 1 / 5, more preferably 4 / 5 to 2 / 5, and even more preferably 3 / 4 to 1 / 2 of the width of the user's wrist.
[0060] In the embodiments of the present invention, A (cm, ratio) to B (cm, ratio) can be used in appropriate combinations with respect to each other, regardless of expressions such as "preferably," "more preferably," or "even more preferably."
[0061] By setting the size of the gap 12 within the above range, discomfort caused by contact between the C-shaped bangle and the user's wrist when the user flexes their hand can be reduced.
[0062] <2-4> Curve Forming Process Next, the curve forming process S24 of the present invention will be described with reference to Figures 3, 5, and 6. The curve forming process S24 of the present invention includes the thumb-side arc curve forming process S24-1 and the little finger-side arc curve forming process S24-2.
[0063] <2-4-1> Thumb-side arc curve formation process S24-1 includes a step of forming the curve of the thumb-side arc portion such that the curvature of the position of the thumb-side arc portion relative to the abductor pollicis longus tendon is maximized when the user wears the C-shaped bangle, based on the measured position of the user's abductor pollicis longus tendon.
[0064] Here, forming the curve of the thumb-side arc portion such that the curvature at the position opposite the abductor pollicis longus tendon in the thumb-side arc portion is greatest means that (1) when the forearm is horizontal (for example, the forearm is placed on a horizontal surface such as a desk), and the abductor pollicis longus tendon 51 is located palmar with respect to the thickness direction of the wrist (see Figure 5(a)), the process includes forming the curve of the lower part of the thumb-side arc portion 52 (see Figure 5(b)) such that the curvature of the lower part of the thumb-side arc portion 52 is greatest.
[0065] Furthermore, forming the curve of the thumb-side arc portion such that the curvature at the position opposite the abductor pollicis longus tendon in the thumb-side arc portion is greatest means that (2) when the forearm is horizontal (for example, the forearm is placed on a horizontal surface such as a desk), and the abductor pollicis longus tendon 51 is located near the center of the wrist with respect to the thickness direction of the wrist (see Figure 6(a)), the curve of the thumb-side arc central portion 62 (see Figure 6(b)) is greatest.
[0066] The thumb-side arc portion curve formation step S24-1 includes the step of forming the curve of the thumb-side arc portion 13 so that when the user puts the C-shaped bangle on their wrist and the user dorsiflexes their hand, the upper band portion 11 does not compress the user's finger extensor tendons.
[0067] The thumb-side arc portion curve formation step S24-1 includes the step of forming the curve of the thumb-side arc portion 13 such that when the user puts the C-shaped bangle on their wrist and the user flexes their hand, the position opposite the palmaris longus tendon and / or the flexor carpi radialis muscle is near the center of the gap portion 12.
[0068] The thumb-side arc portion curve formation step S24-1 includes the step of forming the curve of the thumb-side arc portion 13 so that when the user puts the C-shaped bangle on their wrist and the user flexes their hand palmarly, dorsally, ulnarly, and / or radially, the thumb-side arc portion 13 does not press against the user's wrist.
[0069] By performing the thumb-side arc curve formation step S24-1 in the manner described above, it is possible to provide a design method for a C-shaped bangle that minimizes pressure on the user's wrist even when they move their wrist while wearing the bangle.
[0070] <2-4-2> Little finger side arc curve formation process S24-2 includes the process of forming the curve of the little finger side arc 14 so that when the user puts the C-shaped bangle on their wrist and the user dorsiflexes their hand, the upper girdle portion 11 does not compress the user's finger extensor tendons.
[0071] The little finger side arc curve formation step S24-2 includes the step of forming the curve of the little finger side arc 14 so that when the user puts the C-shaped bangle on their wrist and the user flexes their hand, the center of the gap 12 becomes the user's palmaris longus tendon or the user's radial carpal flexor muscle.
[0072] The little finger side arc curve forming step S24-2 includes forming the curve of the little finger side arc 14 so as not to compress the user's wrist when the user wears the C-shaped bangle on their wrist and the user flexes their hand palmarly, dorsally, ulnarly, and / or radially.
[0073] By performing the curve formation step S24-2 on the little finger side in the manner described above, it is possible to provide a design method for a C-shaped bangle that minimizes pressure on the user's wrist even when they move their wrist while wearing the bangle.
[0074] <2-5> End Adjustment Process Next, the end adjustment process S25 of the present invention will be described. The end adjustment process S25 of the present invention includes the step of adjusting the thumb-side end 15 and / or little-finger-side end 16 so that when the user flexes their hand, the thumb-side end 15 and / or little-finger-side end 16 do not press against the inside of the wrist.
[0075] The end adjustment step S25 of the present invention may include a step of forming the thumb-side end 15 and / or little finger-side end 16 into a substantially semicircular shape.
[0076] By including each of the above steps in the end adjustment process, discomfort caused by contact between the thumb-side end 15 and / or the little finger-side end 16 and the user's wrist when the user flexes their hand and / or abducts, flexes, and / or internally rotates their thumb can be reduced.
[0077] The present invention will be described in more detail below with reference to Figure 4 and examples, but the present invention is not limited to the following examples unless it exceeds the gist of the invention.
[0078] <Wrist Measurement Process S21> The wrist circumference, wrist width, wrist thickness, position of the palmaris longus tendon and flexor carpi radialis muscle, and position of the abductor pollicis longus tendon relative to the wrist thickness were measured for the user (Japanese male) (see Figure 8).
[0079] The results are shown below. Wrist circumference: 16 cm Wrist width: 6 cm Wrist thickness: 4 cm Location of palmaris longus tendon and flexor carpi radialis muscle: Near the center relative to wrist width Location of abductor pollicis longus tendon relative to wrist thickness: Palmar side
[0080] <Process for determining the inner diameter of the C-shaped bangle S22> Based on the wrist measurement process, a silver C-shaped bangle was designed to have a total length of 16 cm, a major diameter of 6 cm, and a minor diameter of 4 cm.
[0081] <Gap Formation Process S23> Since the user's palmaris longus tendon and flexor carpi radialis muscle were located near the center of the wrist width, the curvature of the thumb-side arc portion 13 and the little finger-side arc portion 14 was adjusted so that the positions opposite the palmaris longus tendon and flexor carpi radialis muscle were near the center of the gap portion 12.
[0082] <Process for forming the curve of the thumb-side arc S24-1> Since the position of the abductor pollicis longus tendon relative to the thickness direction of the wrist was on the palmar side, the curve of the lower part of the thumb-side arc 52 was formed so that the curvature of the lower part 52 of the thumb-side arc was maximized.
[0083] <Process for forming the curve of the thumb-side arc portion S24-1> Based on the wrist measurement process, the process for determining the inner diameter of the C-shaped bangle, the gap formation process, and the process for forming the curve of the thumb-side arc portion, a silver C-shaped bangle was manufactured using the grip strength of the hand and a wooden mandrel.
[0084] The silver C-shaped bangle that was manufactured was worn by the user, and when the user flexed their hand, it compressed the extensor tendons of the fingers.
[0085] Therefore, to avoid compressing the user's finger extensor tendons, the curvature of the thumb-side arc portion 13 was increased using a wooden mallet.
[0086] <Curve Formation Process for Little Finger Side Arc Section S24-2> When the user put on the manufactured silver C-shaped bangle and flexed their hand, the little finger side end 16 was pressing against the area around the user's radial carpal flexor muscle.
[0087] Therefore, to avoid compressing the area around the user's radial carpal flexor muscle, the curvature of the little finger side arc portion 14 was increased using a wooden mallet.
[0088] <End Forming Process S25> The thumb-side end 15 and the little finger-side end 16 were formed into a roughly semi-circular shape using a wooden mallet.
[0089] The design method for C-shaped bangles according to the present invention can be used in the manufacture of jewelry and ornaments.
[0090] 1 Metal C-shaped bangle 11 Upper band 12 Gap 13 Thumb-side arc 14 Little finger-side arc 15 Thumb-side end 16 Little finger-side end 17 C-shaped bangle long diameter 18 C-shaped bangle short diameter 5 Right wrist 51 Abductor pollicis longus tendon 52 Lower part of thumb-side arc 62 Middle part of thumb-side arc 71 Palmaris longus tendon 72 Flexor carpi radialis 8 Wrist measurement position
Claims
1. A method for designing a metal C-shaped bangle, wherein the metal C-shaped bangle has an upper band portion, a thumb-side arc portion, a little finger-side arc portion, a thumb-side end portion, a little finger-side end portion, and a gap portion between the thumb-side end portion and the little finger-side end portion, (A) a wrist measurement step of measuring the circumference of the user's wrist, the width of the wrist, the thickness of the wrist, the position of the user's palmaris longus tendon and / or flexor carpi radialis muscle, and the position of the abductor pollicis longus tendon in the thickness direction of the user's wrist, (B) a C-shaped bangle inner diameter determination step of determining the inner diameter of the C-shaped bangle based on the measured values of the user's wrist circumference, wrist width, and wrist thickness, A method for designing a metal C-shaped bangle, comprising: (C) forming the gap portion based on the measured position of the palmaris longus tendon and / or flexor carpi radialis muscle such that when the user wears the C-shaped bangle, the position opposite the palmaris longus tendon and / or flexor carpi radialis muscle is near the center of the gap portion; and (D) forming the curve of the thumb-side arc portion based on the measured position of the abductor pollicis longus tendon such that when the user wears the C-shaped bangle, the curvature of the thumb-side arc portion is maximized.
2. A method for designing a metal C-shaped bangle according to claim 1, further comprising: (E) an end adjustment step of adjusting the thumb-side end and / or the little finger-side end, wherein step (E) includes a step of adjusting the thumb-side end and / or the little finger-side end so that when the user puts the C-shaped bangle on their wrist and flexes their hand, the thumb-side end and / or the little finger-side end do not press against the inside of the user's wrist.
3. The method for designing a metal C-shaped bangle according to claim 1 or 2, wherein step (D) includes the step of forming the curve of the thumb-side arc portion so that when the user puts the C-shaped bangle on their wrist and contracts the abductor pollicis longus tendon, the thumb-side arc portion does not compress the abductor pollicis longus tendon.
4. The method for designing a metal C-shaped bangle according to claim 1 or 2, wherein step (D) includes the step of forming the curves of the thumb-side arc portion and / or the little-finger-side arc portion so that when the user puts the C-shaped bangle on their wrist and the user dorsiflexes their hand, the upper band portion does not compress the user's finger extensor tendons.
5. The method for designing a metal C-shaped bangle according to claim 1 or 2, wherein step (D) includes the step of forming the curves of the thumb-side arc and / or the little-finger-side arc so that when the user puts the C-shaped bangle on their wrist and the user flexes their hand, the thumb-side arc does not compress the abductor pollicis longus tendon.
6. A method for designing a metal C-shaped bangle according to claim 1 or 2, comprising processing the C-shaped bangle so that the contact surface with the user's wrist is curved.