Screws and clocks

Abstract

To provide a screw which can improve quality by preventing a scratch, and a clock having the same.SOLUTION: On a bottom part of a slit groove 10 which is formed at a screw head part 8 and into which a tip part 9a of a screwdriver 9 is inserted, a suppression groove 12 being a suppression part for suppressing the loosening of the tip part 9a of the screwdriver 9 in a screw-drive direction in a state that the tip part of the screwdriver is inserted into the slit groove is formed along a longitudinal direction of the slit groove 10. Therefore, when the tip part 9a of the screwdriver 9 inserted into the slit groove 10 is pressed against an inner face of the suppression groove 12, the tip part 9a of the screwdriver 9 can be suppressed by the inner face of the suppression groove 12 so that the loosening of the tip part 9a of the screwdriver 9 in the screw-drive direction is not generated. By this constitution, a scratch of the screwdriver 9 in an insertion direction is alleviated, and the generation of a scratch on the tip part 9a of the screwdriver 9 in the screw-drive direction can be surely and favorably suppressed.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a screw and a timepiece equipped with the same. [Background technology]

[0002] For example, as described in Patent Document 1, there is known a screw having a structure in which a slit groove is provided in the head of the screw into which the tip of a flat-head screwdriver is inserted. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-119037

[0004] In this type of screw, the inner wall surfaces on both sides in the width direction perpendicular to the longitudinal direction of the slit groove are formed into a parabolic curve that gradually narrows from the opening side toward the bottom surface. Therefore, when inserting the tip of a screwdriver into the slit groove, the tip of the screwdriver can be guided by the inner wall surfaces on both sides of the slit groove, making it easy to insert the tip of the screwdriver into the slit groove. Summary of the Invention [Problem to be solved by the invention]

[0005] However, with such screws, when the tip of the screwdriver is inserted into the slit groove in the screw head, the tip of the screwdriver abuts and rubs against the inner wall surfaces on both sides of the slit groove, causing scratches on the inner wall surfaces of the slit groove.Since these scratches on the inner wall surfaces are visible from the outside and are easily noticeable, this is undesirable in appearance and leads to a decrease in the quality of the product.

[0006] The problem to be solved by this invention is to provide a screw that can reduce rubbing in the direction of inserting the screwdriver and suppress rubbing in the direction of turning the screw, and a timepiece equipped with the screw. [Means for solving the problem]

[0007] In order to solve the above problems, a screw according to a first aspect of the present invention is When the tip of the screwdriver is inserted into the slit groove, the play in the screw-driving direction of the tip of the screwdriver is at the bottom of the slit groove that is provided in the head of the screw and into which the tip of the screwdriver is inserted. of A suppressing portion is provided along the longitudinal direction of the slit groove. A screw, The slit groove has a first inner wall surface extending from one end of the suppression portion and a second inner wall surface extending from the other end of the suppression portion, The first inner wall surface and the second inner wall surface are formed to be parallel to the axial direction of the screw. The screw is characterized by the above. In order to solve the above-mentioned problems, a screw according to a second aspect of the present invention is a screw in which a suppression portion is provided along the longitudinal direction of a slit groove that is provided in a screw head and into which a tip end of a screwdriver is inserted, and that prevents a part of the tip end of the screwdriver from contacting the bottom portion when the tip end of the screwdriver is inserted into the slit groove, The slit groove has a first inner wall surface extending from one end of the suppression portion and a second inner wall surface extending from the other end of the suppression portion, The screw is characterized in that the first inner wall surface and the second inner wall surface are formed to be surfaces parallel to the axial direction of the screw. [Effects of the Invention]

[0008] According to this invention, it is possible to reduce scratches in the inserting direction of the screwdriver and also to suppress scratches in the turning direction of the screwdriver. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is an enlarged front view showing an embodiment of a wristwatch to which the present invention is applied. [Figure 2] FIG. 2 is an enlarged rear view of the wristwatch shown in FIG. [Figure 3] 3 is an enlarged cross-sectional view showing the main parts of the wristwatch shown in FIG. 2 taken along the line AA. [Figure 4] 4 shows the screw shown in FIG. 3, where (a) is an enlarged front view thereof, (b) is an enlarged side view showing the screw head, and (c) is an enlarged view showing part A in (a). [Figure 5] FIG. 5 is an enlarged cross-sectional view of the screw shown in FIG. 4(b) as viewed from the arrow BB. [Figure 6] 1A and 1B show a first modified example of a screw to which the present invention is applied, in which (a) is an enlarged front view thereof, (b) is an enlarged side view showing the screw head, and (c) is an enlarged view showing part B of (a). [Figure 7] 1A and 1B show a second modified example of the screw to which the present invention is applied, in which (a) is an enlarged front view thereof, (b) is an enlarged side view showing the screw head, and (c) is an enlarged view showing part C of (a). DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment in which the present invention is applied to a wristwatch will now be described with reference to FIGS. As shown in Figures 1 and 2, this wristwatch has a wristwatch case 1 made of metal such as stainless steel. On the 12 o'clock and 6 o'clock sides of this wristwatch case 1, there are band attachment sections 2 to which a watch band (not shown) can be attached.

[0011] As shown in Figures 1 and 2, switch units 3 are provided on the 2 o'clock, 3 o'clock, and 4 o'clock sides of this wristwatch case 1. A crystal 4 is fitted into the upper opening of this wristwatch case 1. A watch module (not shown) is also provided inside this wristwatch case 1.

[0012] 2 and 3, a back cover 5 made of a metal such as stainless steel is attached to the lower part of this watch case 1 (the upper part in FIG. 3) with multiple screws 6. In this case, screw insertion holes 5a are provided in the vertical direction at multiple locations on the four corners of the back cover 5, namely at the 1 o'clock, 5 o'clock, 7 o'clock, and 11 o'clock sides, into which threaded portions 7 of the screws 6, which will be described later, are inserted. Counterbore portions 5b, into which screw heads 8 of the screws 6, which will be described later, are placed, are provided at locations on the back cover 5 corresponding to these multiple screw insertion holes 5a.

[0013] 2 and 3, at the four lower corners on both sides of the band attachment section 2 of the watch case 1, i.e., at the 1 o'clock, 5 o'clock, 7 o'clock, and 11 o'clock sides, there are provided threaded holes 1a into which the screws 6 are threaded, each of which is coaxial with the screw insertion holes 5a in the back cover 5. Each of these threaded holes 1a has a female screw groove 1b spirally formed on its inner circumferential surface.

[0014] In this case, a circular recess 1d is provided at the lower opening (upper opening in Fig. 3) in the screw hole 1a, as shown in Fig. 3. The inner diameter of this recess 1d is larger than the inner diameter of the screw hole 1a and is approximately the same size as the outer diameter of the screw head 8 of the screw 6. Furthermore, the length (depth) of this recess 1d in the axial direction of the screw hole 1a is shorter than the axial length of the screw head 8.

[0015] As shown in Fig. 3, a cylindrical spacer 1c is placed in this circular recess 1d. This spacer 1c is made of an insulating synthetic resin. The outer diameter of this cylindrical spacer 1c is approximately the same as the inner diameter of the recess 1d and the outer diameter of the screw head 8 of the screw 6, and the inner diameter is slightly larger than the outer diameter of the threaded portion 7 of the screw 6.

[0016] 3, the spacer 1c is formed so that its axial length is shorter than that of the screw head 8 and slightly longer than that of the recess 1d. As a result, when the spacer 1c is placed in the recess 1d of the screw hole 1a of the watch case 1, it is configured to protrude from the bottom of the watch case 1 (the top in FIG. 3).

[0017] For this reason, as shown in Figure 3, this spacer 1c is positioned to protrude from the bottom of the watch case (top in Figure 3), so that when the back cover 5 is attached to the bottom of the watch case 1 with screws 6, a gap is created between the watch case 1 and the back cover 5, preventing contact between the watch case 1 and the back cover 5. In other words, this watch is configured so that the watch case 1 and the back cover 5 do not come into contact with each other, because if the watch case 1 and the back cover 5 come into contact, the radio wave reception sensitivity of the watch module antenna (neither shown) will decrease.

[0018] As shown in Figures 3 and 4, each of the multiple screws 6 is a flat-head screw that gives a luxurious feel and is made of a highly rigid metal such as stainless steel. The screws 6 include a threaded portion 7 and a screw head 8. The threaded portion 7 has a male screw groove 7a spirally formed on its outer surface and is configured to thread into the screw hole 1a of the watch case 1 through the screw insertion hole 5a in the back cover 5. In other words, the threaded portion 7 is configured so that the male screw groove 7a on its outer surface helically meshes with the female screw groove 1b on the inner surface of the screw hole 1a in the watch case 1 and screws into it.

[0019] 3 and 4, the outer diameter of screw head 8 is larger than the inner diameter of screw insertion hole 5a in back cover 5, and is approximately 1.5 to 2 times the outer diameter of threaded portion 7. As a result, when threaded portion 7 is screwed into threaded hole 1a in watch case 1 and tightened, screw head 8 is positioned in counterbore 5b of screw insertion hole 5a in back cover 5, and is configured to press back cover 5 against the underside of watch case 1 (the upper surface in FIG. 3).

[0020] In this case, as shown in Figure 3, when the back cover 5 is pressed toward the underside (top side in Figure 3) of the watch case 1 by tightening the screw head 8, it is pressed against the end of the spacer 1c that is positioned within the recess 1d of the screw hole 1a and protrudes from the underside (top side in Figure 3) of the watch case 1, creating a gap between it and the underside of the watch case 1 and preventing it from coming into contact with the underside of the watch case 1.

[0021] As shown in Figures 4(a) to 4(c), the screw head 8 is provided with a slit groove 10, into which the tip 9a of a flat-head screwdriver 9 is inserted, along a straight line passing through the center of the screw head 8. In this case, the screwdriver 9 is an existing one, and the tip 9a is formed in a tapered plate shape. The slit groove 10 is formed so that its longitudinal length is the same as the diameter of the screw head 8, and its width S, which is perpendicular to the longitudinal direction, is about 1 / 5 of the longitudinal length and is wider than the thickness of the tip 9a of the screwdriver 9.

[0022] In this case, in Figures 4(a) and 4(c), the thickness of the tip 9a of the screwdriver 9 is shorter than the widthwise length of the slit groove 10, but the thickness of the tip 9a of the screwdriver 9 may be thicker than the thickness shown in Figures 4(a) and 4(c) as long as it is thick enough to be inserted into the slit groove 10.

[0023] In this case, as shown in Figures 4(a) and 4(c), the inner wall surfaces 10a on both sides of the slit groove 10 are formed as vertical surfaces that are parallel to the axial direction of the screw 6. As a result, when the tip 9a of the screwdriver 9 is inserted into the slit groove 10, the tip 9a of the screwdriver 9 is inserted with almost no contact with the inner wall surfaces 10a, reducing scratches on the inner wall surfaces 10a on both sides caused by the tip 9a of the screwdriver 9 in the insertion direction and making the scratches caused by the tip 9a of the screwdriver 9 in the insertion direction less noticeable.

[0024] 4(a) and 4(c), the slit groove 10 is formed so that the length (depth) of the inner wall surfaces 10a on both sides in the axial direction of the screw 6 is shorter than the axial length (thickness) of the screw head 8, and is approximately the same as or slightly shorter than the width S of the slit groove 10. A suppression groove 12, which is a suppression part that suppresses play in the tip 9a of the screwdriver 9 in the screw driving direction, is provided at the bottom of the slit groove 10 along the longitudinal direction of the slit groove 10.

[0025] 4(a) and 4(c), the suppression groove 12 has an arc-shaped cross section in the width direction perpendicular to the longitudinal direction of the slit groove 10. That is, the radius of curvature R of the arc-shaped suppression groove 12 is set within a range from approximately the same as the length S of the slit groove 10 in the width direction to approximately 1 / 3 of the length S of the slit groove 10 in the width direction (S>R>1 / 3S).

[0026] In this case, as shown in Figures 4(a) and 4(c), it is desirable that the radius of curvature R of the arc of the arc-shaped suppression groove 12 is set to 1 / 2 the length S of the width direction of the slit groove 10 (R = 1 / 2S). In other words, when the radius of curvature R of this arc-shaped suppression groove 12 is set to 1 / 2 the length S of the width direction of the slit groove 10 (R = 1 / 2S), the cross-sectional shape of the arc-shaped suppression groove 12 is formed into a groove shape that is semicircular.

[0027] Furthermore, when the curvature radius R of the suppression groove 12 is set to the same length as the width direction length S of the slit groove 10 (R=S), the cross-sectional shape is formed into a groove shape that is an arc shape that is more gentle and curved than a semicircle. Furthermore, when the curvature radius R of the suppression groove 12 is set to about 1 / 3 the width direction length S of the slit groove 10 (R=1 / 3S), the cross-sectional shape is formed into a groove shape that is the same as a part of an ellipse that is curved less than a semicircle.

[0028] As shown in Figures 4(a) and 4(c), such a screw 6 is configured so that when the tip 9a of a flat-head screwdriver 9 is inserted into the suppression groove 12 through the slit groove 10, the edge portions 9b on both sides of the thickness direction of the tip 9a of the screwdriver 9 are pressed against the arcuate surface of the suppression groove 12.

[0029] For this reason, as shown in Figures 4(a) and 4(c), when the tip 9a of the screwdriver 9 is pressed against the arcuate surface of the suppression groove 12, play in the screw-turning direction at the tip 9a of the screwdriver 9 is suppressed so that no play occurs in the screw-turning direction at the tip 9a of the screwdriver 9.

[0030] As a result, as shown in Figures 4(a) and 4(c), when the tip 9a of the screwdriver 9 inserted into the suppression groove 12 of the slit groove 10 is rotated in the screwdriving direction, the edge portions 9b on both sides of the thickness direction of the tip 9a of the screwdriver 9 do not rub against the arcuate surface of the suppression groove 12, and the screw head 8 is reliably rotated by the tip 9a of the screwdriver 9.

[0031] In this case, as shown in Figures 4(a) to 4(c), chamfered portions 8a are provided on the outer periphery of the screw head 8 and on each edge of the inner wall surfaces 10a on both sides of the slit groove 10. Also, as shown in Figures 3 and 5, a decorative layer 6a is provided on the surface of this screw 6 by surface treatment. This decorative layer 6a is a vapor deposition layer formed by a vapor deposition process such as ion plating (IP), or a plated layer formed by a plating process.

[0032] This decorative layer 6a is decorated in colors such as silver, gold, brown, blue, and black. In this case, the decorative layer 6a may be provided on the entire surface of the screw 6 as shown in Fig. 5, but it is sufficient that it is provided within a range E that extends from the screw head 8 toward the threaded portion 7 and is approximately half the axial length of the entire screw 6. In addition, a locking resin (not shown) is applied to the threaded portion 7 of this screw 6 to prevent the threaded portion 7 from loosening from the screw hole 1a in the watch case 1.

[0033] Next, a description will be given of how the back cover 5 is attached to the bottom of the watch case 1 using such screws 6. In this case, cylindrical spacers 1c made of insulating synthetic resin are placed in advance in the recesses 1d of the multiple screw holes 1a provided in the four corners of the lower part (upper part in FIG. 3) of the watch case 1. At this time, each end of the multiple spacers 1c is placed so that it protrudes from the lower surface (upper surface in FIG. 3) of the watch case 1.

[0034] In this state, the back cover 5 is placed on the underside of the watch case 1, and the multiple screw insertion holes 5a in the back cover 5 are aligned coaxially with the multiple screw holes 1a and multiple spacers 1c provided in the bottom of the watch case 1. Then, a locking resin (not shown) is applied to each of the threaded portions 7 of the multiple screws 6, and the threaded portions 7 of the multiple screws 6 are inserted through the multiple screw insertion holes 5a in the back cover 5 into the multiple cylindrical spacers 1c on the watch case 1, so that they each correspond to the multiple screw holes 1a in the watch case 1.

[0035] In this state, the tip 9a of the screwdriver 9 is inserted into the slit groove 10 of the screw head 8. At this time, the width S of the slit groove 10 is formed to be sufficiently wider than the thickness of the tip 9a of the screwdriver 9, so when the tip 9a of the screwdriver 9 is inserted into the slit groove 10, the tip 9a of the screwdriver 9 does not come into contact with the inner wall surfaces 10a on both sides within the slit groove 10, and therefore the tip 9a of the screwdriver 9 does not scratch the inner wall surfaces 10a on both sides.

[0036] Furthermore, when the tip 9a of the screwdriver 9 is inserted into the slit groove 10 and inserted into the arc-shaped suppression groove 12, the edge portions 9b on both sides in the thickness direction of the inserted tip 9a of the screwdriver 9 are pressed against the arc-shaped surface of the suppression groove 12. As a result, the edge portions 9b on both sides of the tip 9a of the screwdriver 9 are suppressed from having any play in the screwdriving direction corresponding to the arc-shaped surface of the suppression groove 12. In this state, when the tip 9a of the screwdriver 9 is rotated in the screwdriving direction, the edge portions 9b on both sides of the tip 9a of the screwdriver 9 do not rub against the arc-shaped surface of the suppression groove 12 in the screwdriving direction.

[0037] This causes tip 9a of screwdriver 9 to reliably rotate screw head 8, so that screw portion 7 is threaded into and tightened into screw hole 1a through cylindrical spacer 1c of watch case 1. At this time, locking resin (not shown) applied to screw portion 7 is wedged between male screw groove 7a in screw portion 7 and female screw groove 1b in screw hole 1a in watch case 1, so the tightened screw portion 7 will not loosen.

[0038] As a result, screw portion 7 is tightened into screw hole 1a in watch case 1, and screw head 8 presses back cover 5 against the end of spacer 1c protruding from the underside of watch case 1 (the upper surface in FIG. 3), pressing back cover 5 toward the underside of watch case 1. In this way, back cover 5 is securely attached to watch case 1 by screw 6.

[0039] In this case, the end of spacer 1c protrudes from the underside of watch case 1 (the top side in FIG. 3), so when back cover 5 is attached to watch case 1 with screws 6, a gap is provided between back cover 5 and watch case 1 to prevent back cover 5 from coming into contact with watch case 1. This prevents a decrease in the radio wave reception sensitivity of the antenna (neither of which is shown) inside the watch module.

[0040] Incidentally, when the tip 9a of the screwdriver 9 is rotated in the screwdriving direction, the edge portions 9b on both sides of the tip 9a of the screwdriver 9 do not rub against the arcuate surface of the suppression groove 12 in the screwdriving direction, so the edge portions 9b of the screwdriver 9 do not cause scratches on the arcuate surface of the suppression groove 12 in the screwdriving direction.

[0041] In this case, even if a decorative layer 6a is provided on the screw head 8 and slit groove 10 of the screw 6 by surface treatment such as ion plating or plating, when the tip 9a of the screwdriver 9 is rotated in the screw-driving direction, the decorative layer 6a is not scratched in the screw-driving direction by the edge portions 9b on both sides of the tip 9a of the screwdriver 9.

[0042] As a result, the screw 6 is decorated with the decorative layer 6a, which enhances the design and commercial value, while also ensuring and improving the quality of the product. In this case, even if scratches are made on the arcuate surface of the suppression groove 12, the tip 9a of the screwdriver 9 does not directly contact the arcuate surface or the center of the suppression groove 12, so there is no significant impact on the appearance. In addition, the arcuate surface of the suppression groove 12 reflects light from outside and converges the reflected light toward the inside of the slit groove 10, so the scratches are difficult to see from the outside and are not noticeable.

[0043] Furthermore, when the back cover 5 is attached to the watch case 1 using the multiple screws 6 provided at multiple locations on the four corners of the back cover 5, namely the 1 o'clock, 5 o'clock, 7 o'clock, and 11 o'clock sides, the longitudinal directions of the slit grooves 10 of the multiple screw heads 8 are all aligned in one direction, as shown in Figure 2, thereby improving the appearance and enhancing the design.

[0044] Thus, with the screw 6 of this wristwatch, a suppression groove 12, which is a suppression part that suppresses play in the tip 9a of the screwdriver 9 in the turning direction when the tip 9a of the screwdriver 9 is inserted into the slit groove 10, is provided at the bottom of the slit groove 10 that is provided in the screw head 8 and into which the tip 9a of the screwdriver 9 is inserted, and is provided along the longitudinal direction of the slit groove 10.This reduces scratches on the tip 9a of the screwdriver 9 in the insertion direction and also suppresses scratches on the tip 9a of the screwdriver 9 in the turning direction.

[0045] That is, with this screw 6, when the tip 9a of the screwdriver 9 is inserted into the slit groove 10, it is possible to reduce scratches on the inner wall surface 10a of the slit groove 10 caused by the tip 9a of the screwdriver 9. Furthermore, when the tip 9a of the screwdriver 9 inserted into the slit groove 10 is pressed against the inner surface of the suppression groove 12, the play in the screwdriving direction of the tip 9a of the screwdriver 9 can be suppressed by the inner surface of the suppression groove 12 so that no play is generated in the screwdriving direction of the tip 9a of the screwdriver 9. Therefore, it is possible to reliably and effectively suppress scratches in the screwdriving direction of the tip 9a of the screwdriver 9, thereby improving quality.

[0046] In this case, when the tip 9a of the screwdriver 9 is inserted into the slit groove 10, a portion of the tip 9a of the screwdriver 9 does not come into contact with the bottom, thereby reliably and effectively preventing scratches from occurring in the screw turning direction on the tip 9a of the screwdriver 9. Furthermore, when the tip 9a of the screwdriver 9 is inserted into the slit groove 10, the edge portions 9b at both ends of the tip 9a of the screwdriver 9 come into contact, and the rest of the tip 9a is not in contact, thereby reliably and effectively preventing scratches from occurring in the screw turning direction on the tip 9a of the screwdriver 9.

[0047] Furthermore, in this screw 6, the cross-sectional shape of the suppression groove 12 in the width direction perpendicular to the longitudinal direction of the slit groove 10 is arc-shaped, so when the tip 9a of the screwdriver 9 is pressed against the arc-shaped surface of the suppression groove 12, the edge portions 9b on both sides of the thickness direction of the tip 9a of the screwdriver 9 are pressed against the arc-shaped surface of the suppression groove 12.Therefore, the arc-shaped surface of the suppression groove 12 can reliably suppress any play in the screw-turning direction at the tip 9a of the screwdriver 9 so that no play occurs in the screw-turning direction at the tip 9a of the screwdriver 9.

[0048] As a result, this screw 6 can reliably and effectively prevent scratches on the tip 9a of the screwdriver 9 in the direction of screwing, and since it only requires providing an arc-shaped suppression groove 12 in the bottom of the slit groove 10, the structure is simple and can be easily manufactured, which increases productivity and allows for lower prices.

[0049] Furthermore, in this screw 6, the radius of curvature R of the suppression groove 12 is set within a range from approximately the same length as the length S of the slit groove 10 in the width direction perpendicular to the longitudinal direction to approximately 1 / 3 of the length S of the slit groove 10 in the width direction (S>R>1 / 3S), so that when the tip 9a of the screwdriver 9 is pressed against the arcuate surface of the suppression groove 12, the edge portions 9b on both sides in the thickness direction of the tip 9a of the screwdriver 9 can be pressed well against the arcuate surface of the suppression groove 12. As a result, the arcuate surface of the suppression groove 12 can reliably and well suppress play in the screwdriving direction at the tip 9a of the screwdriver 9 so that play does not occur in the screwdriving direction at the tip 9a of the screwdriver 9.

[0050] In this case, in this screw 6, if the radius of curvature R of suppression groove 12 is set to half the length S of slit groove 10 in the width direction (R=1 / 2S), the cross-sectional shape of suppression groove 12 will be semicircular, allowing edge portions 9b on both sides in the thickness direction of tip portion 9a of screwdriver 9 to be reliably and satisfactorily pressed against the semicircular arc surface of suppression groove 12. Therefore, the semicircular arc surface of suppression groove 12 can reliably and satisfactorily suppress play in the screw turning direction at tip portion 9a of screwdriver 9, so that play does not occur in the screw turning direction at tip portion 9a of screwdriver 9.

[0051] Furthermore, in this screw 6, a decorative layer 6a is provided on the surfaces of the screw head 8 and the slit groove 10 by surface treatment, so that the screw head 8 can be decorated with this decorative layer 6a, thereby enhancing the design. In this case, in this screw 6, even if the decorative layer 6a is provided on the arcuate surface of the suppression groove 12 in the slit groove 10, when the screw head 8 is rotated with the screwdriver 9, it is possible to prevent scratches on the decorative layer 6a from being made in the screw-turning direction by the tip 9a of the screwdriver 9.

[0052] This allows for improved decorativeness and design, as well as increased commercial value and quality, in this screw 6. In this case, even if scratches are made on the arcuate surface of the suppression groove 12, the tip 9a of the screwdriver 9 does not directly contact the arcuate surface or the center of the suppression groove 12, so there is no significant impact on the appearance. In addition, the arcuate surface of the suppression groove 12 reflects light from outside and can converge the reflected light toward the inside of the slit groove 10, making the scratches less visible from the outside and making them less noticeable.

[0053] In the above-described embodiment, the cross-sectional shape of the suppression groove 12 is described as being arc-shaped, but the present invention is not limited to this. For example, as in the first modified example shown in Figures 6(a) to 6(c), the cross-sectional shape of the suppression groove 20 in the width direction perpendicular to the longitudinal direction of the slit groove 10 may be V-shaped, or as in the second modified example shown in Figures 7(a) to 7(c), the cross-sectional shape of the suppression groove 21 in the width direction perpendicular to the longitudinal direction of the slit groove 10 may be inverted trapezoidal.

[0054] That is, the suppression groove 20 having a V-shaped cross-sectional shape in the first modified example shown in Figures 6(a) to 6(c) only needs to have an axial length (depth) H that is within the range from approximately the same length as the widthwise length S of the slit groove 10 perpendicular to the longitudinal direction to approximately 1 / 3 of the widthwise length S of the slit groove 10 (S>H>1 / 3S).

[0055] In this case, it is desirable that the axial length H of the suppression groove 20 of the first modified example is approximately half the widthwise length S of the slit groove 10 (H=1 / 2S). Furthermore, it is desirable that the cross-sectional shape of this suppression groove 20 is an isosceles triangle, but this cross-sectional shape does not necessarily have to be an isosceles triangle. The suppression groove 20 of this first modified example also has the same effects as the above-mentioned embodiment.

[0056] Furthermore, the suppression groove 21 in the second modified example shown in Figures 7(a) to 7(c), whose cross-sectional shape is an inverted trapezoid, may have an axial length (depth) T within the range from approximately the same length as the widthwise length S perpendicular to the longitudinal direction of the slit groove 10 to approximately 1 / 3 of the widthwise length S of the slit groove 10 (S>T>1 / 3S).

[0057] In this case, it is desirable that the axial length T of suppression groove 21 of the second modified example is approximately half the widthwise length S of slit groove 10 (T=½S). Furthermore, it is desirable that the length of the base of suppression groove 21 in the cross-sectional shape is approximately the same as the thickness of tip 9a of screwdriver 9, but this is not limiting, and the length of the base may be shorter or longer than the thickness of tip 9a of screwdriver 9. Such suppression groove 21 of the second modified example also has the same effects as the above-described embodiment.

[0058] Furthermore, in the above-described embodiment and its respective variations, the suppression portion is described as being a suppression groove 12, 20, 21, but this invention does not necessarily require a groove, and may have a structure in which a suppression protrusion is provided on both sides of the width direction at the bottom of the slit groove 10 to suppress play in the screw-driving direction at the tip 9a of the screwdriver 9.

[0059] Furthermore, in the above-described embodiment, the case where the back cover 5 is attached to the bottom of the watch case 1 with screws 6 is described, but the present invention is not limited to this and can also be applied to, for example, a case where an exterior member is attached to the upper outer periphery of the watch case 1 with screws 6.

[0060] Furthermore, although the above-described embodiment has been described as being applied to a wristwatch, the present invention does not necessarily have to be a wristwatch, but can be applied to various types of timepieces, such as travel watches, alarm clocks, table clocks, wall clocks, etc. Furthermore, the present invention does not necessarily have to be a timepiece, but can be applied to electronic devices such as mobile phones and personal digital assistants, as well as a wide range of devices that require screw fastening.

[0061] Although one embodiment of the present invention has been described above, the present invention is not limited to this and includes the inventions set forth in the claims and their equivalents. The inventions described in the claims of this application are as follows:

[0062] (Addendum) The invention described in claim 1 is a screw characterized in that a suppression portion is provided along the longitudinal direction of a slit groove provided in the head of the screw and into which the tip of a screwdriver is inserted, at the bottom of the slit groove, which suppresses play in the screw-turning direction at the tip of the screwdriver when the tip of the screwdriver is inserted into the slit groove.

[0063] The invention described in claim 2 is a screw characterized in that a suppression part is provided along the longitudinal direction of a slit groove at the bottom of the slit groove, into which the tip of the screwdriver is inserted, so that when the tip of the screwdriver is inserted into the slit groove, a part of the tip of the screwdriver does not come into contact with the bottom.

[0064] The invention described in claim 3 is the screw described in claim 1, characterized in that the suppression portion is such that when the tip of the screwdriver is inserted into the slit groove, a part of the tip of the screwdriver does not come into contact with the bottom portion.

[0065] The invention described in claim 4 is a screw described in any one of claims 1 to 3, characterized in that when the tip of the screwdriver is inserted into the slit groove, the suppression portion is in contact with both end edge portions of the tip of the screwdriver, and is not in contact with any portion other than the end edge portions.

[0066] The invention described in claim 5 is a screw characterized in that, in the screw described in any one of claims 1 to 4, the suppression portion is a suppression groove whose cross-sectional shape in the width direction perpendicular to the longitudinal direction of the slit groove is formed in an arc shape.

[0067] The invention described in claim 6 is the screw described in claim 5, characterized in that the curvature radius of the suppression groove is set within a range from approximately the same length as the width direction length perpendicular to the longitudinal direction of the slit groove to approximately 1 / 3 of the width direction length of the slit groove.

[0068] The invention described in claim 7 is a screw characterized in that, in the screw described in any one of claims 1 to 4, the suppression portion is a suppression groove whose cross-sectional shape in the width direction perpendicular to the longitudinal direction of the slit groove is V-shaped.

[0069] The invention described in claim 8 is a screw described in claim 1, characterized in that the suppression portion is a suppression groove whose cross-sectional shape in the width direction perpendicular to the longitudinal direction of the slit groove is formed in an inverted trapezoid shape.

[0070] The invention described in claim 9 is a screw described in any one of claims 1 to 4, characterized in that the suppression portion is provided at both ends of the bottom of the slit groove in a width direction perpendicular to the longitudinal direction of the slit groove.

[0071] The invention as set forth in claim 10 is the screw as set forth in any one of claims 1 to 9, characterized in that a decorative layer is provided on the screw head and the slit grooves by surface treatment.

[0072] The invention described in claim 11 is a timepiece characterized by including a screw described in any one of claims 1 to 10. [Explanation of symbols]

[0073] 1 watch case 1a screw hole 1b Thread groove 5 Back cover 5a Screw insertion hole 5b Counterbore 6 screws 6a Decorative layer 7 Threaded section 7a screw groove 8 screw head 9. Screwdriver 9a Tip 9b Edge 10 Slit groove 12, 20, 21 Suppression groove R radius of curvature S length

Claims

1. A screw in which a suppression portion that suppresses play in the screw turning direction at the tip end of a screwdriver when the tip end of the screwdriver is inserted into a slit groove that is provided in a head of the screw and is provided at the bottom of the slit groove along the longitudinal direction of the slit groove, The slit groove has a first inner wall surface extending from one end of the suppression portion and a second inner wall surface extending from the other end of the suppression portion, The first inner wall surface and the second inner wall surface are formed to be surfaces parallel to the axial direction of the screw. A screw characterized by:

2. A screw in which a suppression portion is provided along the longitudinal direction of a slit groove that is provided in a screw head and into which a tip of a screwdriver is inserted, the suppression portion preventing a part of the tip of the screwdriver from contacting the bottom portion of the slit groove when the tip of the screwdriver is inserted into the slit groove, The slit groove has a first inner wall surface extending from one end of the suppression portion and a second inner wall surface extending from the other end of the suppression portion, The first inner wall surface and the second inner wall surface are formed to be surfaces parallel to the axial direction of the screw. A screw characterized by:

3. The screw according to claim 1, The suppression portion prevents a part of the tip of the screwdriver from contacting the bottom portion when the tip of the screwdriver is inserted into the slit groove. A screw characterized by:

4. In the screw according to any one of claims 1 to 3, The suppression portion is configured so that, when the tip end of the screwdriver is inserted into the slit groove, edge portions at both ends of the tip end of the screwdriver come into contact with each other, and portions other than the edge portions at both ends do not come into contact with each other. A screw characterized by:

5. The screw according to any one of claims 1 to 4, The suppression portion is a suppression groove having a cross section in a width direction perpendicular to the longitudinal direction of the slit groove, the cross section being formed in an arc shape. A screw characterized by:

6. The screw according to claim 5, The curvature radius of the suppression groove is set within a range from approximately the same length as the length of the slit groove in the width direction perpendicular to the longitudinal direction to approximately 1 / 3 of the length of the slit groove in the width direction. A screw characterized by:

7. The screw according to any one of claims 1 to 4, The suppression portion is a suppression groove having a V-shaped cross section in a width direction perpendicular to the longitudinal direction of the slit groove. A screw characterized by:

8. The screw according to claim 1, The suppression portion is a suppression groove whose cross section in the width direction perpendicular to the longitudinal direction of the slit groove is formed in an inverted trapezoid shape. A screw characterized by:

9. The screw according to any one of claims 1 to 4, The suppression portion is configured to suppress the width of the slit groove in a width direction perpendicular to the longitudinal direction of the slit groove. provided at both ends of the bottom A screw characterized by:

10. The screw according to any one of claims 1 to 9, The screw head and the slit groove are provided with a decorative layer by surface treatment. A screw characterized by:

11. The screw according to any one of claims 1 to 10, The first inner wall surface and the second inner wall surface are opposed to each other and parallel to each other. A screw characterized by:

12. The screw according to any one of claims 1 to 11, The length of the first inner wall surface and the second inner wall surface in the axial direction is approximately equal to the length of the slit groove in the width direction. A screw characterized by:

13. A timepiece comprising the screw according to any one of claims 1 to 12.

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