JP2006018094A - Drip-proof and waterproof structure and camera having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain satisfactory drip-proof and waterproof function by a simple groove structure. <P>SOLUTION: The drip-proof and waterproof structure is constructed by fitting an O-ring 30 into an annular groove 11 formed in a front body shell 10 and then inserting an annular rib 21 into it. The bottom of the annular groove 11 has narrow grooves 12 formed on both sides in the extending direction (x direction) of the bottom. Each narrow groove 12 is in the form of a triangular space that has a cross-section (yz cross-section) perpendicular to the extending direction. On the other hand, the leading edge of the annular rib 21 is chamfered, as shown by a slant face 21, only on one side of the annular rib 21 in the extending direction (x direction), and a space 23 is thereby formed. By pushing the annular rib 21 in a z direction so that the O-ring 30 is elastically deformed, the deformed section is accommodated in the narrow grooves 12 and the space 23. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a drip-proof waterproof structure that holds two members in a watertight state via a seal member, and a camera having a drip-proof waterproof structure.

  When the back cover is brought into close contact with the body of the camera, a drip-proof and waterproof structure is used in order to prevent water droplets from entering the inside from the close contact portions of both. As such a drip-proof waterproof structure, in general, a groove for attaching a packing is formed in one of the body main body or the back cover, and the rubber packing is pressed against the other of the body main body or the back cover to be elastically deformed. Held in a state. In order to ensure this watertight state, a wall portion that divides the bottom portion of the groove for attaching the packing into two groove portions in the width direction is projected, and the cross-sectional shape of the packing is non-circular and asymmetrical according to the shape of the groove portion. Such a waterproof structure is known (see, for example, Patent Document 1).

JP-A-8-106121 (page 3, FIG. 1)

  When the camera is provided with a drip-proof waterproof structure, the cross-sectional dimension of the groove for attaching the packing is limited to a small dimension because of the requirement for compactness of the camera. For example, the groove width is as narrow as about 0.5 mm. If the dimensional variation is large in the groove width or the groove depth, the elastic deformation amount of the rubber packing cannot absorb the variation, and the drip-proof performance is deteriorated. In the technique of Patent Document 1 described above, the drip-proof performance is maintained by devising the cross-sectional shape of the groove and the cross-sectional shape of the packing, but the structure of the groove is complicated and demands for processing tolerances are severe. There is a problem that the processing cost is high.

(1) In order to solve the above-mentioned problem, the drip-proof waterproof structure of the invention according to claim 1 includes a first member in which an annular groove is formed and a second member in which a protrusion that engages with the annular groove is formed. A drip-proof waterproof structure in which a seal member that elastically deforms by receiving the pressing force of the ridge is placed in the annular groove and held in a watertight state inside the housing formed by combining the members with the annular groove. In the bottom portion, a relief portion for accommodating a deformed portion due to elastic deformation of the seal member is formed.
(2) The drip-proof waterproof structure of the invention according to claim 2 is the drip-proof waterproof structure according to claim 1, wherein the relief portions are formed symmetrically on both sides of the bottom surface of the annular groove along the extending direction of the groove. It is a narrow groove. The width of the narrow groove is preferably in the range of 0.2w to 0.4w, where w is the width of the annular groove. Further, the drip-proof waterproof structure of the invention according to claim 4 is the drip-proof waterproof structure according to claims 1 to 3, wherein the tip of the ridge is chamfered on one side along the extending direction of the ridge. Is preferably applied.
(3) The camera of the invention according to claim 5 has the drip-proof waterproof structure according to any one of claims 1 to 4.

  According to the drip-proof waterproof structure of the present invention, since the space for accommodating the deformed portion due to the elastic deformation of the seal member is formed at the bottom of the groove, there is a variation in the dimensions of the groove and the pressing force against the seal member is different However, good drip-proof and waterproof performance can be obtained with a simple groove structure.

Hereinafter, a drip-proof waterproof structure and a camera having the same according to an embodiment of the present invention will be described with reference to FIGS.
FIG. 1A is a perspective view schematically showing an outer shell structure (shell) of a camera having a drip-proof waterproof structure according to an embodiment of the present invention. The camera outer shell 1 has a front body shell 10 and a rear body shell 20, and is manufactured by plastic molding, for example. An opening is formed in the back surface of the front body shell 10, and an opening is also formed in the front surface of the rear body shell 20, and an opening edge surface 10A and an opening edge surface 20A surrounding each of these openings are formed. Can be joined. The opening edge surfaces 10A and 20A are parallel to the xy plane. A plurality of screw receiving portions 22 are provided on the opening edge surface 20A side, and similar screw receiving portions are provided on the opening edge surface 10A side at positions facing the screw receiving portions 22.

  FIG. 1B is a partially enlarged view of the three-dimensional area A in FIG. An annular groove 11 having a shape shown in the figure is formed in the opening edge surface 10A over the entire circumference in the depth z direction, and an annular rib (protrusion) is formed on the opening edge surface 20A so as to engage with the annular groove 11. ) 21 protrudes in the z direction.

  When the opening edge surfaces 10A and 20A are joined to close the opening, the O-ring 30 is fitted in the annular groove 11, and screwed through the screw receiving portion 22 and the screw receiving portion on the opening edge surface 10A side. Thus, the annular rib 21 presses the O-ring 30 in the z direction. The O-ring 30 is elastically deformed by the pressing force and is brought into close contact with the inner wall of the annular groove 11 and the tip of the annular rib 21 with a surface pressure corresponding to the reaction force, so that the opening can be maintained in a watertight state. The O-ring 30 has a circular cross section and is made of a material having a large amount of elastic deformation such as nitrile rubber or fluororubber.

  The drip-proof waterproof structure of the present embodiment is formed by the annular groove 11, the annular rib 21 and the O-ring 30, and the drip-proof waterproof structure will be described in detail below. FIG. 2 is a partial perspective view schematically showing a drip-proof / waterproof structure according to an embodiment of the present invention, and shows directions in three-dimensional orthogonal coordinates so as to correspond to FIG.

  An annular rib 21 is inserted into the annular groove 11 formed in the front body shell 10 after the O-ring 30 is fitted. In FIG. 2, the pressing force of the annular rib 21 on the O-ring 30 is zero. In other words, a state where the O-ring 30 is not deformed is shown. At the bottom of the annular groove 11, narrow grooves 12 are formed on both sides along the extending direction (x direction) of the annular groove 11, and the narrow groove 12 has a transverse section (yz section) extending in the x direction. Is a triangular space. In other words, the bottom of the annular groove 11 has a trapezoidal cross section with the bottom surface 11a as the upper base and the slope 11b as the hypotenuse.

  On the other hand, the tip of the annular rib 21 is chamfered by a slope 21a only on one side along the extending direction (x direction) of the annular rib 21. Therefore, when the annular rib 21 is inserted into the annular groove 11, a space 23 having a triangular cross section (yz section) extending in the x direction above the O-ring 30 is formed. The chamfering amount of the tip portion of the annular rib 21 is set to 1/2 or less of the width dimension of the annular groove 11. This is because if the chamfering amount is ½ or more of the width dimension of the annular groove 11, the pressing force cannot be effectively applied to the O-ring 30.

  The above-mentioned drip-proof waterproof structure has the same shape and dimensions in the vertical cross section in any place in the extending direction by design. However, in manufacturing, the vertical cross section does not necessarily have the same shape and size. For example, if the processing tolerance of the annular groove 11 and the annular rib 21 is ± 10%, a dimensional error of 20% at maximum occurs. . Further, in FIG. 1, the screw tightening force, that is, the pressing force against the O-ring 30 may vary between the position where the screw hole 22 is provided and the position away from the screw hole 22. These processing errors and assembly errors need to be absorbed by the deformation amount of the O-ring 30. That is, in the extending direction of the drip-proof waterproof structure, sufficient water-tightness must be maintained even at a location where the deformation of the O-ring 30 is the smallest.

  If the cross-sectional dimension perpendicular to the extending direction of the drip-proof waterproof structure is increased to increase the contact area of the O-ring 30, the watertightness is enhanced. However, as described above, it is limited to increase the vertical cross-sectional dimension. There is. Therefore, in order to maintain processing and assembly errors and maintain watertightness, the O-ring 30 can be efficiently elastically deformed by devising the shape of the vertical cross section of the drip-proof waterproof structure, and the O-ring 30. The space for accommodating the deformed portion is appropriately provided in the annular groove 11.

  In the drip-proof waterproof structure of the present embodiment, the pressing force of the annular rib 21 against the O-ring 30 is directed in the z direction in FIG. By providing 12), the deformed portion of the O-ring 30 can be accommodated effectively. Further, since the reaction force from the O-ring 30 receiving the pressing force is directed in the −z direction in FIG. 2, the deformed portion of the O-ring 30 is formed by the relief portion 23 formed in the reaction force direction, that is, above the O-ring 30. Can be accommodated. If the O-ring 30 is deformed in this manner, the O-ring 30 can be brought into close contact with the bottom of the annular groove 11 and the tip of the annular rib 21 while covering processing errors and assembly errors of the annular groove 11 and the annular rib 21. it can.

  FIG. 3 is a partial cross-sectional view showing a yz cross-section of the partial perspective view of FIG. 2, and is a view showing dimensions of each part of the annular groove 11 and the annular rib 21. That is, w is the groove width of the annular groove 11, a is the width of the bottom surface 11a, b is the width of the narrow groove 12 in the same plane as the bottom surface 11a, c is the depth of the narrow groove 12, and d is the tip of the annular rib 21. , E represents the chamfering amount of the tip, and θ represents the angle of the inclined surface 11b of the narrow groove 12 with respect to the xy plane. The angle θ of the slope 11b is θ = tan (c / b).

  In this embodiment, w = 0.50 mm, the diameter φ of the O-ring 30 is set to 0.50 mm, and d = 0.28 mm and e = 0.20 mm. Under this condition, the shape of the relief portion 12 (thin groove 12) is considered using the bottom width a, the narrow groove width b, and the narrow groove depth c as parameters. Among these parameters, priority is given to the width a of the bottom surface that contributes most to the O-ring 30 receiving a pressing force from the annular rib 21 and generating a reaction force. The width b of the narrow groove is an amount depending on the width a of the bottom surface because of the relationship of a + 2 × b = w. Further, the depth c of the narrow groove is an amount that can be regarded as being independent of the width a of the bottom surface, and is a parameter that affects the contact state with the O-ring 30, and is therefore second priority.

  FIG. 4 is a graph showing the amount of compression and the magnitude of reaction force when the width a of the bottom surface is used as a parameter. As described above, since the groove width w = 0.50 mm, the narrow groove width b (mm) is b = (0.50−a) / 2. In the figure, the horizontal axis represents the width a of the bottom surface, and the vertical axis represents the amount of compression (the amount of deformation of the O-ring 30 in the pressing force direction) and the reaction force. The compression amount curve A monotonously decreases as the bottom width a increases, but no significant difference is seen in the entire range in the graph of 0.1 to 0.4 mm. On the other hand, the reaction force (actually measured value) curve B increases until the bottom width a is about 0 to 0.1 mm, is almost constant in the range of 0.1 to 0.3 mm, and starts again from about 0.3 mm. It starts to increase. This tendency can be clearly seen from the reaction force (polynomial) curve C.

  According to the above results, when the width a of the bottom surface is 0.1 mm or less, the surface pressure of the O-ring 30 is too low and the deformation behavior becomes unstable. When the width a of the bottom surface is in the range of 0.1 to 0.3 mm, the reaction force is at a relatively high level, and the O-ring 30 is deformed accordingly, and the volume of the escape portion 12 that accommodates the deformed portion is too small. There is nothing. When the volume of the escape portion 12 is simply expressed by the width b of the narrow groove, 0.1 mm ≦ b ≦ 0.2 mm. If the width a of the bottom surface is in the range of 0.3 to 0.4 mm, the surface pressure of the O-ring 30 may be too high, and the volume of the escape portion 12 that accommodates the deformed portion becomes small. There is a risk of being unable to accommodate. As a result obtained from the above, the width a of the bottom surface is in the range of 0.1 to 0.3 mm, in other words, the width b of the narrow groove is in the range of 0.1 to 0.2 mm, that is, 0.2 w to 0.4 w. Is the appropriate range.

  FIG. 5 is a partial cross-sectional view of the drip-proof waterproof structure according to the present embodiment. When the width a of the bottom surface of the drip-proof waterproof structure is within the appropriate range of FIG. It is a figure which shows the state which deform | transformed the O-ring 30 currently fitted by. 5A shows a case where the maximum deformation is applied to the O-ring 30 by the maximum pressing force P. FIG. 5B shows a case where 20% of the maximum pressing force P is applied after the maximum deformation is applied to the O-ring 30. Is shown, that is, when deformation is applied at 80% of the maximum pressing force P. As described above, considering that a dimensional error of 20% at maximum occurs in the annular groove 11 or the annular rib 21, the pressing force is 20% under the assumption that the deformation amount of the O-ring 30 is proportional to the pressing force. Even if it is reduced, it is only necessary to ensure water tightness.

  In FIG. 5A, the O-ring 30 is greatly deformed and most of the deformed portion is accommodated in the escape portion 12 (thin groove 12) and the escape portion 23. As a result, the contact area between the O-ring 30 and the annular groove 11 is also increased. The contact area between the O-ring 30 and the annular rib 21 is also very large. In FIG. 5B, since the maximum pressing force P is reduced by 20%, the contact area between the O-ring 30 and the annular groove 11 and the contact area between the O-ring 30 and the annular rib 21 are reduced as compared with FIG. However, a sufficient area for drip-proofing and waterproofing is secured.

  FIG. 6 is a partial cross-sectional view showing a first comparative example of the drip-proof waterproof structure according to the present embodiment, and the O-ring 30 when the width a of the bottom surface of the drip-proof waterproof structure is not within the proper range of FIG. It is a figure which shows a deformation | transformation state. The comparative example of FIG. 6 shows a case where the dimensions of the annular rib 21 and the O-ring 30 are the same as those of the present embodiment, but the width a of the bottom surface of the annular groove is small (a <0.1 mm). The narrow groove 42 has a sufficient capacity to accommodate the deformed portion of the O-ring 30, but since the area supporting the O-ring 30 is small, when the pressing force is increased, the load is concentrated only on the contact portion of the O-ring 30. Therefore, there is a possibility that the O-ring 30 may be damaged, but it can be used if the pressing force is small.

  FIG. 7 is a partial cross-sectional view shown as a second comparative example of the drip-proof waterproof structure according to the present embodiment, and the width a of the bottom surface of the drip-proof waterproof structure is in the proper range of FIG. It is a figure which shows the deformation | transformation state of O-ring 30 when angle (theta) of this differs from this Embodiment. In the comparative example of FIG. 7A, the angle θ of the inclined surface 51b is 90 ° which is the maximum value. The O-ring 30 may be damaged, but it can be used if the pressing force is small.

  7B is a case where the angle θ of the inclined surface 61b of the narrow groove 62 is increased to increase the depth c of the narrow groove, and the amount of deformation of the O-ring 30 is increased by increasing the pressing force. Even if it is increased, the deformed portion of the O-ring 30 does not reach the inside of the narrow groove 62, and only a useless space is formed. In contrast to FIGS. 7A and 7B, if the angle θ of the inclined surfaces 51b and 61b is too small, the narrow grooves 52 and 62 cannot fully accommodate the deformed portion of the O-ring 30, and the effect of the present embodiment. Cannot be demonstrated. Therefore, there is an appropriate range for the angle θ of the inclined surface of the narrow groove and the depth c of the narrow groove.

  As described above, the drip-proof waterproof structure according to the present embodiment supports the O-ring 30 at the center of the bottom of the groove 11 and provides the narrow grooves 12 on both sides of the bottom, so that the O-ring 30 can be elastically deformed efficiently. The deformed portion can be efficiently accommodated. Further, by setting each part dimension of the groove 11, in particular, the width a of the bottom surface (width b of the narrow groove) within an appropriate range and setting the width b of the narrow groove 12 to 20 to 40% of the width w of the groove 11, The effect becomes even greater. Furthermore, if the angle θ of the inclined surface 11b of the narrow groove 12 is defined after the bottom surface width a (thin groove width b) is determined, the O-ring 30 will not be damaged even if the pressing force is increased. The deformed portion can be accommodated in the space of the narrow groove 12.

Hereinafter, a modified example will be described with reference to FIG. FIG. 8 is a partial cross-sectional view showing a variation of the drip-proof waterproof structure of the present embodiment. FIG. 8A is a partial cross-sectional view of a drip-proof waterproof structure in which a narrow groove 72 is formed at the center of the bottom along the extending direction (x direction) of the annular groove 71. Since the narrow groove 72 is formed at the center of the annular groove 71, the deformed portion of the O-ring 30 can be directly accommodated. FIG. 8B is a partial cross-sectional view of the drip-proof waterproof structure in which the entire area of the bottom surface 81a is inclined in the cross section perpendicular to the extending direction of the annular groove 81. Although the space for accommodating the deformed portion of the O-ring 30 is biased to one side, a large united space can be obtained.
In these modified examples, a part of the O-ring 30 enters the accommodation space from the initial stage of compression, and the surface pressure is likely to be reduced due to dimensional variation. On the other hand, in the present embodiment, since the deformed portion of the O-ring 30 enters the narrow groove (relief portion) at the end of compression, a reduction in surface pressure due to dimensional variation is unlikely to occur.

  The present invention is characterized in that a narrow groove 12 that efficiently accommodates a deformed portion of the O-ring 30 is provided at the bottom of the groove 11. The present invention is not limited to the embodiments described above as long as the characteristics are not impaired.

FIG. 1A is a perspective view schematically showing an outer shell structure (shell) of a camera having a drip-proof waterproof structure according to an embodiment of the present invention. FIG. 1B is a partially enlarged view of the three-dimensional area A in FIG. It is a fragmentary perspective view which shows typically the drip-proof waterproof structure which concerns on embodiment of this invention. It is a fragmentary sectional view which shows yz cross section of the fragmentary perspective view of FIG. In the drip-proof waterproof structure according to the embodiment of the present invention, it is a graph showing the amount of compression and reaction force of the O-ring when the width a of the bottom surface is used as a parameter. It is a fragmentary sectional view of the drip-proof waterproof structure concerning an embodiment of the invention. FIG. 5A is a diagram showing a state in which the O-ring 30 is deformed by the maximum pressing force P, and FIG. 5B is a diagram in which the O-ring 30 is deformed by 80% of the maximum pressing force P. FIG. It is a fragmentary sectional view shown as a 1st comparative example of a drip-proof waterproof structure of an embodiment of the invention. It is a fragmentary sectional view shown as a 2nd comparative example of the drip-proof waterproof structure of an embodiment of the invention. It is a fragmentary sectional view which shows the modification of the drip-proof waterproof structure of embodiment of this invention.

Explanation of symbols

1: Camera 10: Front body shell 10A, 20A :: Open edge 11, 41, 51, 61, 71, 81: Annular groove 11a, 41a: Bottom 11b, 51b, 61b, 81b: Slope 12, 42, 52, 62, 72, 82: narrow groove (flank)
20: Rear body shell 21: Annular rib 22: Screw receiving portion 23: Escape portion 30: O-ring

Claims (5)

The inside of the housing formed by combining the first member formed with the annular groove and the second member formed with the protrusion engaging with the annular groove is pushed into the annular groove. A drip-proof waterproof structure that arranges a seal member that elastically deforms under pressure and holds it in a watertight state,
A drip-proof waterproof structure characterized in that a relief portion for accommodating a deformed portion of the seal member due to elastic deformation is formed at the bottom of the annular groove. In the drip-proof waterproof structure according to claim 1,
The drip-proof waterproof structure characterized in that the escape portion is a narrow groove formed symmetrically on both sides of the bottom surface of the annular groove along the extending direction of the annular groove. The drip-proof waterproof structure according to claim 2,
The width of the narrow groove is in the range of 0.2w to 0.4w, where w is the width of the annular groove, and the drip-proof waterproof structure. In the drip-proof waterproof structure according to claims 1 to 3,
A drip-proof / waterproof structure, wherein a tip portion of the ridge is chamfered on one side along an extending direction of the ridge.   A camera comprising the drip-proof waterproof structure according to claim 1.

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