EP1577717B1

EP1577717B1 - Wristwatch

Info

Publication number: EP1577717B1
Application number: EP03780768.2A
Authority: EP
Inventors: Susumu Shibata; Osamu Takahashi; Hiroshi Matsumura; Yoichi Yaguchi; Michel Ratajski
Original assignee: Namiki Precision Jewel Co Ltd
Current assignee: Namiki Precision Jewel Co Ltd
Priority date: 2002-12-17
Filing date: 2003-12-15
Publication date: 2016-02-03
Anticipated expiration: 2023-12-15
Also published as: CN100504666C; EP1577717A4; CN1726437A; HK1086354A1; WO2004055603A1; KR20050086912A; EP1577717A1; JP2004198183A; KR100935571B1; JP4348599B2

Description

TECHNICAL FIELD

This Invention relates to an improvement of a wristwatch with a super hard wristwatch case which comprises a case body of sintered carbides and ceramics having left/right pairs of leg portions provided at opposite positions thereof, and in which a wristwatch band is supported between the leg portions by means of spring rods.

BACKGROUND ART

Hitherto, there is known a wristwatch case in which left/right pairs of leg portions are provided at opposite positions of a case body and a wristwatch band is attached between the leg portions by means of spring rods (Japanese Patent Application Laid-Open Nos. Hei. 7-231802 and Hei. 10-225309 ). In the wristwatch case, fixing holes between which the spring rods are to be bridged and engaged are formed in inner wall faces of the leg portions.
EP 370 356 A1 discloses a wristwatch having a wristwatch case, a wristwatch band and a pin for attaching the wristwatch band on the wristwatch case between two projecting leg portions. The leg portions have through holes for inserting the pin.
FR 2,743,641 A1 discloses a wristwatch band and a spring pin for attaching the wristwatch band on a buckle between two projecting leg portions. The leg portions have through holes in which bearing parts, each with a blind hole, are inserted. The spring pin is inserted into the blind hole for fixing the wristwatch band.
FR 2 509 487 A is related to a wristwatch case composed of an outer case made of centered hard alloy and an inner case made of stainless steel having a pair of legs at opposite sides for connecting watch bands. The legs outwardly project from a notch formed on the outer case. The watch band has a connecting member at one end thereof. The watch band is connected to the projected legs by engaging a bar with holds formed in the legs and in the connecting member.
As the wristwatch case, there is known a wristwatch case in which a case body is formed of a hard material that is poor in machinability, such as sintered carbide and ceramics. Also, in a super hard wristwatch case, fixing holes for spring rods are formed in inner wall faces of leg portions by applying an electric discharge machining technique directly to the inner wall faces of the leg portions.
In the super hard wristwatch case, on installation and removal of the wristwatch band, fractures, cracks and/or breaks are easily produced in regions of the leg portions around the fixing holes by the installation and removal operations and/or impact applied to the leg portions by a spring action of the spring rods. This may be often a problem in a visual appearance of the wristwatch case. The causes include physical properties on the hard material of the case body that is easy to be broken, as well as microcracks which will be produced due to transformation in a surface layer of the case body which is subjected to the electric discharge machining.

DISCLOSURE OF THE INVENTION

It is an object of this invention to provide a wristwatch which is modified so that installation and removal of spring rods for supporting a wristwatch band will not cause fractures, cracks and/or breaks to be produced in leg portions of .a case body. This is achieved by a wristwatch according to claim 1.
In a preferred embodiment, the case body has notches formed in the inner wall faces of the leg portions thereof. In this case the back cover is fixed to the back of the case body with the projection pieces thereof being fitted and fixed in the notches of the leg portions so as to be flush with the inner wall faces of the leg portions.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is an exploded perspective view of a super hard wristwatch case according to a first embodiment of the present invention;
Fig. 2 is a segmentary perspective view of the super hard wristwatch case of Fig. 1; and Fig. 3 is a fragmentary sectional view of the super hard wristwatch case of Fig. 1.

MODES FOR CARRYING OUT THE INVENTION

Embodiments according to the present invention will be discussed hereinafter with reference to the accompanying drawings. As shown in Fig. 1, an illustrated embodiment includes a case body 1, a back cover 2 and spring rods 3 (only one spring rod 3 is shown in Fig. 1), and is assembled as a wristwatch case in which a wristwatch band 4 is adapted to be supported by the spring rods 3. The case body 1 is formed of a super hard material such as sintered carbide and ceramics. The back cover 2 is formed of shock-resistant metal such as stainless steel.
The case body 1 comprises an outer frame 10 serving as a body, and is provided with left/right pairs of leg portions 11 a, 11 b, 12a, 12b at opposite positions of the outer frame 10. Installation space 13 (generally referred to as "fitting part fork part", viz., "Kanmata" in wristwatch fabrication terminology in Japanese) for the spring rods 3 for supporting the wristwatch band 4 between the leg portions 11a, 11 b, 12a, 12b therethrough are provided between the leg portions 11 a, 11 b, 12a, 12b. The back cover 2 is formed into a flat plate having a contour that allows the back cover 2 to be fitted in the back of the outer frame 10 including the leg portions 11 a, 11 b, 12a, 12b. Each of the spring rods 3 comprises a sleeve 3c, a coil spring (not shown) housed within the sleeve 3c, and left/right protruding pins 3a, 3b elastically supported to the coil spring.
In order to cause the spring rods 3 to be bridged and engaged between the leg portions, on the basis of the wristwatch case assembled from the respective components described above, shock-resistant metallic members are provided in inner wall faces of the leg portions 11 a, 11 b, 12a, 12b. The concrete examples include a first embodiment of the present invention in which the back cover 2 shown in Figs. 1 to 3 is employed.
In the first embodiment, left/right pairs of projection pieces 20a, 20b, 21 a, 21 b are provided at the back cover 2. The projection pieces 20a, 20b, 21 a, 21 b, are formed integrally with the back cover 2, rise up from a surface of the back cover which faces the case body 1, and serve as the metallic members having the same impact resistance as the back cover 2 does. The projection pieces 20a, 20b, 21 a, 21 b are formed with fixing holes 22a, 22b, 23a, 23b for the spring rods in regions thereof that are adjacent tips of the projection pieces 20a, 20b, 21a, 21b.
The case body 1 is formed in inner wall faces of the leg portions 11 a, 11 b, 12a, 12b thereof with notches 14 (only one notch 14 is shown in Fig. 1) in which the projection pieces 20a, 20b, 21 a, 21b are to be fitted. The notches 14 are formed so as to have contours and depths which allow the projection pieces 20a, 20b, 21 a, 21 b to be fitted in the notches 14 so as to be flush with the inner wall faces of the leg portions 11 a, 11 b, 12a, 12b. The four notches 14 can be easily formed at the same time by causing the leg portions to be subjected to electric discharge machining from the same direction.
Necessary components which include a movement, a dial, an armor glass, etc. are assembled to the case body 1 constructed as discussed above. The back cover 2 is then applied to the back of the case body 1 and assembled to the case body 1 by screwing four pins 5a, 5b, 5c (only three pins are shown in Fig. 1) into through- holes 24a, 24b, 25a, 25b of the back cover 2 and then screwing them into the case body, whereby the super hard wristwatch case or a wristwatch is assembled.
In the wristwatch case constructed as discussed above, as shown in Fig. 2, the projection pieces of the back cover 2 (only one projection piece 20a is shown in Fig. 2) are fitted and fixed in the notches 14 of the leg portions (only one leg portion 11 a is shown in Fig. 2) and flush with the inner wall faces of the leg portions so as not to be exposed to the exterior, so that the wristwatch case can be assembled so as to have a form usual in an ornamental design.
When the wristwatch band 4 is to be attached to the wristwatch case, as shown in Fig. 3, the projecting pins of the spring rods 3 are fitted in the fixing holes of corresponding projection pieces, whereby the spring rods 3 are bridged and engaged between the corresponding projection pieces (only thee projecting pin 3a and the fixing hole 22a of the projection piece 20a are shown in Fig. 3). The projection pieces are formed integrally with the back cover 2 as the metallic members which are formed of shock-resistant metal such as stainless steel as discussed above, so that any impact applied to the projection pieces on installation and removal of the spring rods will not cause any fractures, cracks and/or breaks to be produced in the projection pieces.
In addition, it is unnecessary to provide fixing holes for the spring rods in the leg portions of the case body and the leg portions of the case body 1 can be reinforced by the projection pieces of the back cover, so that fractures, cracks and/or breaks will be prevented from being produced in the leg portions of the case body 1.
As discussed above, the super hard wristwatch case according to the present invention is provided with the shock-resistant metallic back cover having the left/right pairs of the projection pieces provided on the surface thereof which faces the case body, the left/ right pairs of the projection pieces being located so as to be opposed to the inner wall faces of the leg portions of the case body, the projection pieces being formed with the fixing holes for the spring rods in the regions of the projection pieces which are adjacent the tips of the projection portion, and the projection pieces of the back cover being fitted and fixed in the inner wall faces of the leg portions. The spring rods for supporting the wristwatch band are bridged and engaged between the projection pieces. Thus, the simple modification to the structure of the wristwatch case, in which the spring rods for supporting the wristwatch band are bridged and engaged between the projection pieces, can prevent any fractures, cracks and/or breaks from being produced in the leg portions of the case body on the installation and removal of the spring rods from the case.
In the above described embodiment, or in the case where the projection pieces having the fixing holes for the spring rods are provided at the back cover, the back cover is assembled and fixed to the case body with the projection pieces thereof being fitted in the notches of the leg portions so as to be flush with the inner wall faces of the leg portions, so that the wristwatch case can be assembled so as to have a form usual in an ornamental design.
Incidentally, the terms and expressions which have been employed are used as terms of description, not of limitation. For example, the term "left/right pairs of leg portions" is given to mean both the left/right pairs of the leg portions and left/right pairs of portions corresponding in shape to the left/right leg portions. There is no intention in the use of such terms and expressions of excluding any equivalents of the elements or features shown and described or portions thereof. It is recognized that various modifications are possible within the scope of the invention claimed.

Claims

A wristwatch with a super hard wristwatch case comprising:
a case body (1) of sintered carbide and ceramics having left/right pairs of leg portions (11 a, 11 b, 12a, 12b) or left/right pairs of portions corresponding in shape to said leg portions (11 a, 11 b, 12a, 12b) that are provided at opposite positions of said case body (1);

a back cover (2) which is fixed to a back of said case body (1);

a wristwatch band (4) formed separately from said case body (1) and said back cover (2);

spring rods (3) for supporting said wristwatch band (4) between said leg portions (11 a, 11 b, 12a, 12b); and

installation spaces (13) between said leg portions (11a, 11b, 12a, 12b) of said case body (1) for supporting one end of wristwatch band (4),

characterised in that

said back cover (2) is formed of shock-resistant metal and has left/right pairs of projection pieces (20a, 20b, 21 a, 21 b) integrally formed with the back cover (2),

said projection pieces (20a, 20b, 21 a, 21 b) protruding from said back cover (2) in a direction perpendicular to the surface of said back cover (2) so as to be opposed to inner wall faces of said leg portions (11 a, 11 b, 12a, 12b) of said case body (1),

said projection pieces (20a, 20b, 21 a, 21 b) being formed with fixing holes (22a, 22b, 23a, 23b) for said spring rods (3) in regions thereof which are adjacent tips of said projection pieces (20a, 20b, 21 a, 21 b), and

said projection pieces (20a, 20b, 21 a, 21 b) of said back cover (2) are fitted and fixed in said inner wall faces of said leg portions (11 a, 11 b, 12a, 12b) and

said wristwatch band (4) is fixed by spring rods (3) being bridged and engaged between said fixing holes (22a, 22b, 23a, 23b) of said projection pieces (20a, 20b, 21a, 21 b) without the need to provide further fixing holes for the spring rod (3) in said leg portions (11a, 11b, 12a, 12b) to fix the spring rods (3).
The wristwatch according to claim 1, characterised in that said case body (1) has notches (14) formed in said inner wall faces of said leg portions (11a, 11b, 12a, 12b) thereof, and said back cover (2) is fixed to said back of said case body (1) with said projection pieces (20a, 20b, 21 a, 21 b) thereof being fitted and fixed in said notches (14) of said leg portions (11 a, 11 b, 12a, 12b) so as to be flush with said inner wall faces of said leg portions (11 a, 11b, 12a, 12b).