JPH1031146A - Light shielding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a device which is large in contact power with a shaft and substantially prevents the occurrence of light leakage by providing the contact surface of a seal lip part with another member with a projecting part of a specific value or below in height to an annular form and bringing the projecting part as a light shielding surface into contact with the other member. SOLUTION: The light shielding seal consists of a ring 2 for reinforcement and a rubber ring 3. The fixing part 3a of the ring 3 and the ring 2 for reinforcement are adhered or vulcanized and adhered. The contact surface of the seal lip part 3b of the ring 3 is provided with the projecting part 4. At the time of contact, the seal lip part 3b is bent to about 90 deg. and is brought into contact with the shaft 5 by the projecting part 4. At this time, the elasticity of the seal lip part 3b consisting of a rubber elastic material concentrates to one point and, therefore, the contact force with the shaft 5 increases and light shieldability is improved. The excessively large projecting part 4 is the cause for an increase of sliding resistance and, therefore, the better result is obtd. if the projecting part is smaller. Since the thickness of the contact part of the seal is >=0.5mm, the height of the projecting part 4 is made smaller than 0.5mm as well.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light shielding device for shielding light, and more particularly to a light shielding seal for a zoom lens portion of a camera.

[0002]

2. Description of the Related Art A light-shielding seal for a camera does not exert much force on the seal itself as compared with an oil seal or the like.
Sliding is performed at a relatively low speed and infrequently.
The following has been used. Light shielding seal 1 in FIG.
Reference numeral 00 denotes a plurality of cuts 101 formed on the inner diameter side of a ring made of resin or felt. The light-shielding seal 200 shown in FIG. 2 includes a reinforcing portion 201 made of a metal or resin ring, The seal lip 202 made of a body ring is adhered, and in both cases, when used, as shown in FIG.
3 is inserted, and the seal lip 202 is deformed into an L-shape, so that the seal lip 202 comes into close contact with the shaft 203, and prevents light and dust from entering when the camera enters and exits the zoom lens unit due to zoom up or the like. To reduce the resistance during sliding, use PTFE with a small coefficient of friction for the material, or use PT
FE coating may be applied.

[0003]

However, in the case of the above-mentioned prior art, since the entire lip portion is in contact with the shaft and the contact area is large, the contact force is small, and the shaft surface or the sliding surface of the seal is used. If there is a foreign substance adhered or small projections on the surface, light leakage is likely to occur.

The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a light-shielding device which has a large contact force with a shaft and does not easily leak light. It is in.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, according to the present invention, light is shielded so that light does not leak from an annular gap between two members which are mounted concentrically and relatively movable. An annular fixing portion fixed to one of the two members, and a seal made of a flat washer-shaped rubber-like elastic body having a contact portion of 0.5 mm or less in sliding contact with the other member. And a lip portion concentrically with the seal lip portion, the contact surface of the seal lip portion with the second member having an annular height of 0.1 mm.
A protrusion of 5 mm or less is provided, and the protrusion is used as a light-shielding surface and is in contact with the second member.

In addition, two or more convex portions may be provided, and in this case, the height of the convex portion on the inner diameter side may be equal to or lower than the height of the convex portion on the outer side. Further, it is preferable to provide at least one protrusion at a position within 2 mm from the inner diameter end of the seal.

In the light-shielding device configured as described above, despite the extremely simple configuration, the contact area between the seal lip and the second member is small and the contact force is large. Can be effectively prevented,
Even when a foreign substance infiltrates between the seal lip and the second member, or when a small convex portion exists on the shaft surface, the contact force is high, so that a gap is hardly generated, and light leakage hardly occurs.

The projection is provided over the entire surface of the seal lip on the contact surface side with the second member.

Here, it is preferable that the seal lip is formed of a low-hardness rubber-like elastic material to suppress the deformation of the projection.

[0010] Thus, the real contact area between the projection and the second member can be suppressed.

[0011]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the dimensions of the components described in this embodiment,
The material, shape, relative arrangement, and the like are not intended to limit the scope of the present invention only to them unless otherwise specified. (Embodiment 1) FIGS. 4 to 6 show a light-shielding seal of a zoom lens portion of a compact camera as a light-shielding device according to a first embodiment of the present invention. 4 shows a light-shielding seal when a shaft is inserted, and FIGS. 5 and 6 show a light-shielding seal when a shaft is not inserted.

The light-shielding seal 1 comprises a reinforcing ring 2 made of metal or resin and a ring 3 made of rubber as a rubber-like elastic body as shown in FIG. 5, and as shown in FIG. When the seal cross section is enlarged, the rubber ring 3
a and the seal lip portion 3b. Here, the fixing portion 3a and the auxiliary ring 2 are bonded or vulcanized. A convex portion 4 is provided on the contact surface of the seal lip portion 3b. At the time of the contact, the seal lip portion 3b is bent at about 90 degrees as shown in FIG. At this time, since the elastic force of the seal lip portion made of rubber elastic material is concentrated at one point,
The contact force with the shaft is increased, and the light shielding property is improved. However,
If the protrusion is too large, it will cause an increase in sliding resistance, so it is better to use a small protrusion. Since the thickness of the contact portion of the seal is 0.5 mm or less as shown in FIG. 0.5mm
The following is assumed. In addition, if the convex portion is not near the inner diameter end, the convex portion does not contact, or a portion other than the convex portion (inner diameter end) also contacts,
As a result, the peak of the surface pressure of the convex portion does not occur, and it is difficult to exhibit the effect. Therefore, the convex part is near the inner diameter end (2 m from the inner diameter end).
m or less).

(Embodiment 2) FIG. 7 shows a second embodiment of the present invention. This is provided with two convex portions in the first embodiment. Here, in order to make the plurality of protrusions contact each other, it is necessary to make the height of the protrusion on the inner diameter side equal to or lower than that on the outer diameter side as shown in FIG. 7B. As described above, when a plurality of protrusions are provided, the number of protrusions is one.
Although the sliding resistance increases as compared with the two cases, the sealing performance is improved. Other configurations and operations are the same as those of the first embodiment, so that the same components are denoted by the same reference characters and description thereof is omitted.

FIG. 8 shows a difference in contact force between the above two embodiments and a conventional seal. Here, the graphs of (d) to (f) show the state with the axis inserted.
The contact force with respect to the shaft of each of the three seals having the cross-sectional shapes (a) to (c) is analyzed by the finite element method. The horizontal axis indicates the distance from the inner diameter end, and the vertical axis indicates the contact force per radian when radially cut from the center of the seal. From these three graphs, it can be seen that the seal according to the present invention causes concentration and increase of contact force as compared with the conventional seal. 9 (a) to 9 (c) correspond to FIG.
It is a detailed view of (a)-(c).

FIGS. 10 (a) to 10 (f) show examples of convex portions of the light shielding device according to the present invention. (A) is radius 0.1
The projection has a 5 mm arc-shaped cross section. (B) is a convex portion having a chevron-shaped cross section formed by a slope having slopes of 60 degrees and 30 degrees at the tip of an arc having a radius of 0.1 mm. (C) is a convex portion having a chevron-shaped cross section formed by a circular arc having a radius of 0.1 mm at the tip and inclined at 45 degrees and 70 degrees. (D) is a convex portion having a mountain-shaped cross section in which inclined surfaces having an inclination of 30 degrees are joined to form a peak. (E) is a projection having a mountain-shaped cross section in which a slope of 70 degrees and a slope of 45 degrees are joined to form a peak.
(F) is a convex portion having a square cross section with a height of 0.15 mm.

Of these, the light-shielding device has a convex portion having an arc-shaped cross section or a chevron-shaped cross section of (a) to (e).
When the cross-sectional shape of the projection is a square as in (f), the peak of the surface pressure does not occur and the effect is hardly exhibited.

(Embodiment 3) FIG. 11 shows a light shielding device 11 according to a third embodiment of the present invention.

This is to prevent light leakage due to the attachment of foreign matter or the like by providing the minute projections 14 on the entire sliding surface.
That is, even if foreign matter adheres to the sliding surface, light leakage hardly occurs because the sealing is performed by any one of the minute convex portions 14.

In the light-shielding devices according to the first and second embodiments, since the contact is made at the tip of the projection, the surface pressure at the tip of the projection becomes extremely high, and the tip of the projection starts at the time of sliding. It is desirable to apply a PTFE coating to the sliding surface of the seal for the purpose of suppressing the sliding resistance because the lip turning (FIG. 12) tends to occur.

On the other hand, in the light-shielding device according to the present embodiment, if a rubber-like elastic material which is not easily deformed (has a large compressive strength) is used as the material of the seal lip, the concave portion of the sliding surface is in contact with the shaft. (FIG. 13), the true contact area and the surface pressure can be reduced, and the Fr reduction is aimed at.
Without PTFE coating, it is possible to prevent the occurrence of lip turn-up and improve productivity.

In the light-shielding device according to the present embodiment, if one mold having many small concave portions is prepared at the time of manufacturing, the light-shielding device can be applied to various sizes of light-shielding devices. It is possible to share the mold, and further improve the productivity.

Other configurations and operations are the same as those of the first embodiment, and therefore, the same components will be denoted by the same reference characters and description thereof will be omitted.

[0023]

According to the present invention, a convex portion having a height of 0.5 mm or less is annularly provided on the contact surface of the lip with the second member, and the convex portion contacts the sliding surface as a light shielding surface. Despite the simple configuration, the contact area between the seal lip and the second member is small, the contact force is large, foreign matter can be effectively prevented from entering, and the seal lip and the second member can be effectively prevented.
Light leakage hardly occurs even when a foreign substance infiltrates the member or when a small convex portion exists on the shaft surface.

Further, by providing two or more projections,
The sealing property is improved as compared with the case where only one protrusion is provided.

By making the height of the convex portion on the inner diameter side equal to or lower than the height of the convex portion on the outer diameter side, even when a plurality of convex portions are provided, all of them are easily in contact with each other, and the sealing property is improved. Is easy to improve.

Further, since at least one projection is provided at a position within 2 mm from the end of the inner diameter of the seal, it is easy to come into contact with the sliding surface only by the projection.

Further, since the convex portion is provided over the entire surface of the seal lip portion on the contact surface side with the second member, a mold provided with a large number of minute concave portions may be used at the time of manufacturing. If one is prepared, it can be applied to light-shielding devices of various sizes, the mold can be shared, and the productivity can be improved.

Since the seal lip is formed of a rubber-like elastic material having a large compressive strength to suppress the deformation of the projection, the true contact area and the surface pressure thereof can be reduced.
Aiming at reduction, without PTFE coating,
The occurrence of lip turning can be prevented, and productivity can be improved.

[Brief description of the drawings]

FIG. 1A is a plan view of a conventional light shielding device,
(B) is a partially cutaway sectional view seen from the front.

FIG. 2A is a plan view of a conventional light shielding device,
(B) is a partially cutaway sectional view seen from the front.

FIG. 3 is a schematic configuration diagram when a conventional light shielding device is used.

FIG. 4 is a first embodiment of a light shielding device according to the present invention.
It is a schematic block diagram at the time of use of.

FIG. 5A is a plan view of a first embodiment of a light shielding device according to the present invention, and FIG. 5B is a partially cutaway sectional view as viewed from the front.

FIG. 6 is a first embodiment of a light shielding device according to the present invention;
FIG. Here, (a) is a cross-sectional enlarged view of the light-shielding device according to the present invention, and (b) is a further cross-sectional enlarged view of the convex portion.

FIG. 7 is a second embodiment of the light shielding device according to the present invention.
FIG. Here, (a) is a cross-sectional enlarged view of the light-shielding device according to the present invention, and (b) is a further cross-sectional enlarged view of the convex portion.

FIG. 8 is a diagram showing the relationship between the shape of the light shielding device and the contact force. (A) is a figure which shows the general | schematic shape at the time of use of the conventional light shielding device, (b) is a figure which shows the general | schematic shape at the time of use of the light shielding device concerning Embodiment 1 of this invention, (c) FIG. 9 is a diagram showing a schematic shape when the light shielding device according to the second embodiment of the present invention is used. (D) to (f) are graphs showing the contact force by the finite element method analysis in the states (a) to (c), respectively.

9 (a), 9 (b) and 9 (c) are detailed views of the shapes of FIGS. 8 (a), (b) and (c).

FIGS. 10A to 10F are enlarged cross-sectional views showing examples of the shape of the convex portion of the light shielding device according to the present invention.

FIG. 11 is a schematic sectional view of a light shielding device according to a third embodiment of the present invention.

FIG. 12 is an explanatory diagram of lip turning.

FIG. 13 is a diagram showing a difference in a contact state of a lip portion due to a material.

[Explanation of symbols]

 1, 11, 100, 200: light-shielding seal 2, 201: reinforcing ring 3, 202: rubber ring 3a: fixing portion 3b: seal lip portion 4: convex portion 5, 203: shaft 101: cut

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[Procedure amendment]

[Submission date] May 21, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Brief description of drawings

[Correction method] Change

[Correction contents]

[Brief description of the drawings]

FIG. 1A is a plan view of a conventional light shielding device,
(B) is a partially cutaway sectional view seen from the front.

FIG. 2A is a plan view of a conventional light shielding device,
(B) is a partially cutaway sectional view seen from the front.

FIG. 3 is a schematic configuration diagram when a conventional light shielding device is used.

FIG. 4 is a first embodiment of a light shielding device according to the present invention.
It is a schematic block diagram at the time of use of.

FIG. 5A is a plan view of a first embodiment of a light shielding device according to the present invention, and FIG. 5B is a partially cutaway sectional view as viewed from the front.

FIG. 6 is a first embodiment of a light shielding device according to the present invention;
FIG. Here, (a) is a cross-sectional enlarged view of the light-shielding device according to the present invention, and (b) is a further cross-sectional enlarged view of the convex portion.

FIG. 7 is a second embodiment of the light shielding device according to the present invention.
FIG. Here, (a) is a cross-sectional enlarged view of the light-shielding device according to the present invention, and (b) is a further cross-sectional enlarged view of the convex portion.

FIG. 8 is a diagram showing the relationship between the shape of the light shielding device and the contact force. (A) is a figure which shows the general | schematic shape at the time of use of the conventional light shielding device, (b) is a figure which shows the general | schematic shape at the time of use of the light shielding device concerning Embodiment 1 of this invention, (c) FIG. 9 is a diagram showing a schematic shape when the light shielding device according to the second embodiment of the present invention is used. (D) to (f) are graphs showing the contact force by the finite element method analysis in the states (a) to (c), respectively.

9 (a), 9 (b) and 9 (c) are detailed views of the shapes of FIGS. 8 (a), (b) and (c).

FIGS. 10A to 10F are enlarged cross-sectional views showing examples of the shape of the convex portion of the light shielding device according to the present invention.

FIG. 11 is a schematic sectional view of a light shielding device according to a third embodiment of the present invention.

FIG. 12 is an explanatory diagram of lip turning.

[1 3] Figure 13 is a diagram showing a difference in contact of the lip portion by the material.

[Description of Signs] 1, 11, 100, 200: Light-shielding seal 2, 201: Reinforcing ring 3, 202: Rubber ring 3a: Fixed portion 3b: Seal lip portion 4・ ・ ・ Protrusion 5,203 ・ ・ ・ Shaft 101 ・ ・ ・ Cut

Claims (6)

[Claims] 1. An annular fixing member fixed to one of two members, which shields light so as not to leak light from an annular gap between the two members which are assembled so as to be relatively movable concentrically with each other. Part and the other member in sliding contact, and the contact part has a thickness of 0.1 mm.
And a seal lip of a rubber-like elastic body having a flat washer shape of 5 mm or less, and a concentric projection having a height of 0.5 mm or less on the contact surface of the seal lip with the second member. A light-shielding device, wherein the light-shielding device is provided with the convex portion and the second member is used as a light-shielding surface. 2. The light-shielding device according to claim 1, wherein two or more projections are provided. 3. The light-shielding device according to claim 2, wherein a height of the convex portion on the inner diameter side is equal to or lower than a height of the convex portion on the outer diameter side. 4. The light-shielding device according to claim 1, wherein at least one of the projections is provided at a position within 2 mm from the inner diameter end of the seal. 5. The light-shielding device according to claim 1, wherein the convex portion is provided over the entire surface of the seal lip portion on the contact surface side with the second member. apparatus. 6. The light-shielding device according to claim 5, wherein the seal lip is formed of a rubber-like elastic body having a large compressive strength to suppress the deformation of the projection.