JPH0756077A - Lens barrel - Google Patents

Abstract

PURPOSE:To easily prevent dew condensation on the inner surface of a lens by a general user at low cost without impairing outside appearance by making inside space communicate with outside space through a communicating hole formed in a lens barrel part and constituting the communicating hole so that it can be sealed by a sealing member. CONSTITUTION:The communicating hole 11a through which the inside space 14 communicates with the outside space 15 is formed in the lens barrel 11 and sealed by the sealing member 12. The member 12 is made of a member having elasticity such as rubber, etc., and produced in a size almost within the thickness of the lens barrel 11, and attached to the communicating hole 11a, thereby attaining attachment. When the dew condensation occurs on the inner surfaces L1a and L2a of the lenses L1 and L2, in such a case, the sealing member 12 is detached to feed dry air into the inside space 14 from the hole 11a so as to replace air in the space 14 with the dry air. Therefore, a condensed waterdrop is removed without performing disassembling work, and the dew condensation is prevented from occurring on the lenses L1 and L2 again by sealing the hole 11a by the member 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens barrel having an internal space hermetically sealed between lenses mounted on a lens barrel portion.

[0002]

2. Description of the Related Art Conventionally, in this type of lens barrel,
Condensation may occur on the front lens that is in direct contact with the external environment where the environment such as humidity changes drastically (the external space of the lens barrel). In this case, water droplets can be removed from the outer surface of the lens by wiping or evaporation. However, when dew condensation occurs on the inner surface of the lens, the condensed water drops must be evaporated or decomposed to remove the water drops, and the lens must be reassembled.

[0003] In order to solve this problem
In 150905, (1) a desiccant chamber is formed outside the lens barrel, and an air path is provided between the desiccant chamber and the lens element.
A method for constantly drying the air between lens elements (see Fig. 1), and (2) forming a hygroscopic coating on the inner surface of the lens barrel between one lens element and another lens element or another optical element. A method is disclosed (see Figure 2).

[0004]

However, in the above-mentioned conventional lens barrel, in the case of (1), the desiccant chamber is attached to the outside of the lens barrel in a protruding state, so that the appearance is remarkably increased. And the operability was deteriorated by touching the desiccant chamber while holding the camera. In addition, when the performance of the desiccant deteriorates, the desiccant chamber must be removed and replaced, and it cannot be replaced if there is a dedicated facility, which makes maintenance difficult for general users.

In the case of the above (2), when the performance of the hygroscopic coating film is deteriorated, the lens barrel has to be disassembled and coated again, resulting in high maintenance cost. In addition, after assembly, adjustment is necessary to satisfy the optical performance.
In any of the above cases, the airtightness and watertightness of the lens barrel may be impaired, and moisture may enter with the air from the outside, causing condensation.

The object of the present invention is to solve the above-mentioned problems,
It is an object of the present invention to provide a lens barrel that allows general users to easily and inexpensively prevent dew condensation on the inner surface of a lens without damaging the appearance.

[0007]

The present invention solves the above-mentioned problems by the following means for solving the problems. In addition, in order to facilitate understanding, the description will be given with the reference numerals corresponding to the embodiments, but the present invention is not limited thereto. That is, the first solution means of the lens barrel according to the present invention is a lens barrel having an internal space hermetically sealed between at least two lenses (L1, L2) mounted on the lens barrel portion. The inner space (14) and the outer space (1).
5) with a communication hole (11a) communicating with the sealing member (12), which has a size within a range of approximately the wall thickness of the lens barrel portion and which can be attached to and detached from the communication hole to seal the communication hole. It is characterized by having.

A second solving means is characterized in that, in the lens barrel of the first solving means, a desiccant (53) for drying the internal space is inserted into the communication hole. A third solving means is the lens barrel of the first solving means, wherein a desiccant (23, 33, 43) for drying the internal space is inserted inside the sealing member (22, 32, 42). It is characterized by In a fourth solution means, in the lens barrel of the second or third solution means, the desiccant is replaceable (23, 33, 43, 53). In a fifth solution means, in the lens barrel of the second to fourth solution means, a filter member (47, 57) having moisture permeability is provided between the internal space and the desiccant. To do.

[0009]

In the first solving means, the internal space and the external space can be communicated with each other by the communication hole formed in the lens barrel portion, and the dry air can be introduced from the communication hole. Further, the communication hole can be sealed with a sealing member.

In the second or third solution means, the desiccant is inserted inside the communication hole or the sealing member, so that the water content in the gas in the internal space can be reduced. In the fourth solution, since the desiccant can be replaced, general users can perform maintenance themselves. In the fifth solution, since a filter member having moisture permeability is provided between the internal space and the desiccant, a large number of fine desiccants can be used.

[0011]

EXAMPLES Examples will be described below with reference to the drawings.
This will be described in more detail. FIG. 1 is a sectional view showing a first embodiment of the lens barrel according to the present invention. In the lens barrel 11 of this embodiment, the lenses L1 and L2 are fixed, and the inner surface L1a of the lens L1 and the inner surface L2a of the lens L2 are fixed.
And the inner space 14 sealed by the lens barrel inner surface 11b
Are formed. The outer surface L1b of the lens L1 is in direct contact with the outside world.

A communication hole 11a is formed in the lens barrel 11 to connect the internal space 14 and the external space 15 and is sealed by a sealing member 12. The sealing member 12 is made of an elastic material such as rubber so as to have a size within the range of the thickness of the lens barrel 11, and can be attached to and removed from the communication hole 11a.

In the first embodiment, when dew condensation occurs on the inner surfaces L1a and L2a of the lenses L1 and L2, the sealing member 12 is removed and the communication hole 11a formed in the lens barrel 11 is formed.
The dry air is sent into the internal space 14 from the internal space 14
Can be replaced with air. Therefore, the condensed water droplets can be removed without performing the disassembling work, and the sealing member 12 can seal the water droplets, so that the condensation can be prevented from occurring again in the lenses L1 and L2.

FIG. 2 is an enlarged sectional view showing a main part of a second embodiment of the lens barrel according to the present invention. In each of the embodiments described below, the parts having the same functions as those of the first embodiment are designated by the same reference numerals and the duplicated description will be omitted. In the second embodiment, the communication hole 21a formed in the lens barrel 21 is sealed by the sealing member 22. The sealing member 22 has a recess 22a formed therein, and a solid desiccant 23 such as silica gel is pressed into the recess 22a.

Since the desiccant 23 is in contact with the internal space 24 of the lens barrel 21, it is possible to absorb the water present in the internal space 24 and causing the dew condensation without the need for the decomposition work. The sealing member 22 is made of rubber and has a communication hole 21a.
Since it is in close contact with, it is possible to prevent the intrusion of moisture from the outside. Further, the desiccant 23 is used as the recess 2 of the sealing member 22.
When the performance of the desiccant 23 deteriorates, the desiccant 23 in the concave portion 22a is replaced after the sealing member 22 is removed from the lens barrel 21, so that the communication hole 2a is pressed.
1a may be sealed again by the sealing member 22.

Further, the communication hole 21a is formed in the lens barrel 21.
Since the spot facing portion 21a-1 is formed on the ridge to form a stepped hole, the flange portion 22b of the sealing member 22 is formed in the counterbore portion 21a.
-1 does not enter and does not protrude from the outer diameter of the lens barrel 21.

FIG. 3 is an enlarged sectional view showing a main part of a third embodiment of the lens barrel according to the present invention. The lens barrel 31 of the third embodiment has a female screw formed in the communication hole 31a. The sealing member 32 is made of metal and has a male screw formed on the outer circumference, and is screwed to the female screw. The sealing member 32 projects beyond the inner surface of the lens barrel 31 in order to maximize the screwing width, but is within a range that does not block effective photographing light. The desiccant 33 is used as the sealing member 3.
The second concave portion 32a is inserted into and fixed to the inner side of the concave portion 32a so as not to be influenced by the reflection of light rays occurring on the inner surface of the lens barrel 31. Further, the seal member 36 is sandwiched between the head portion of the sealing member 32 and the spot facing portion 31a-1 of the communication hole 31a by applying a preload. For this reason, the water from the external space 35 causes the communication hole 31a due to the capillary phenomenon.
It is possible to prevent intrusion from the threaded portion of the sealing member 32. By forming the seal member 36 as an O-ring or a rubber sheet, it is possible to prevent water from entering due to elastic deformation. Further, the sealing member 32 is made of an elastically deformable substance such as plastic, so that the elastic deformation of the sealing member 32 can prevent the ingress of water without using the sealing member 36.

FIG. 4 is an enlarged sectional view showing an essential part of a fourth embodiment of the lens barrel according to the present invention. In the lens barrel 41 of the fourth embodiment, the desiccant chamber 41b having a larger diameter than that is formed in the small communication hole 41a. The small communication hole 41a is covered with a filter member 47 having high moisture permeability from the outside. Sealing member 4
Reference numeral 2 is made of resin and is thin, and has a large recess 42a. The sealing member 42 has a plurality of small desiccants 43 inserted into the recesses 42a and fitted into the desiccant chamber 41b. Therefore, in the fourth embodiment, since a plurality of small desiccants 43 can be used, the volume is increased, the amount of moisture absorption can be increased, and the filter member 47 is provided between the inner space 44 and Even the fine desiccant 43 does not enter the internal space 44. Further, with this structure, it can be provided in a thin portion of the lens barrel 41.

FIG. 5 is an enlarged sectional view showing an essential part of a fifth embodiment of the lens barrel according to the present invention. The lens barrel 51 of the fifth embodiment has a relatively thick portion, and has a small communication hole 51a, a desiccant chamber 51b for containing a desiccant 53, and a female screw chamber for screwing a sealing member 52. 51
c is formed so that the diameter increases in sequence. A filter member 57 similar to that of the fourth embodiment is attached between the communication hole 51a and the desiccant chamber 51b. Then, after the desiccant 53 is inserted into the desiccant chamber 51b, the elastic member 58 such as rubber is sandwiched, and the female screw chamber 51c is inserted.
The sealing member 52 is screwed into the. Therefore, in the fifth embodiment, a large desiccant 53 can be used, the drying effect is good, and handling such as replacement is easy. Further, since the elastic member 58 is inserted between the sealing member 52 and the desiccant 53, the elastic member 58 of FIG.
In the same manner as 6), it is possible to prevent the intrusion of water, and the desiccant 53 does not directly contact the sealing member 52 made of metal or the like due to vibration or the like, and thus it is possible to prevent the occurrence of collision noise.

The present invention is not limited to the embodiments described above, and various modifications and changes are possible, which are also included in the present invention. In the first and second embodiments, the example of the material of the sealing member is rubber, but other materials such as plastic may be used as long as it has appropriate elasticity and performs the same function. A tape may be used as the sealing member. In this case, it is desirable to attach a non-slip ring or the like on the outer side to cover it.

[0021]

As described in detail above, according to the first aspect, since the internal space and the external space can be communicated with each other by the communication hole formed in the lens barrel portion, the dry air is introduced from the communication hole. This makes it possible to easily remove the condensed water droplets without decomposing. Further, since the communication hole can be sealed by the sealing member, it is possible to prevent dew condensation again.

According to the second or third aspect of the invention, since the desiccant is inserted inside the communication hole or the sealing member, it is possible to reduce the water content in the gas in the internal space and keep the dry state for a long time. Can be kept.

According to claim 4, since the desiccant can be replaced, a general user can perform maintenance by himself, and the maintenance cost can be reduced.

According to the fifth aspect, since the filter member having moisture permeability is provided between the internal space and the desiccant, even if a large number of fine desiccants are used, they do not enter the internal space. The volume of the desiccant can be increased, and the moisture absorption efficiency can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of a lens barrel according to the present invention.

FIG. 2 is an enlarged cross-sectional view showing a main part of a second embodiment of the lens barrel according to the present invention.

FIG. 3 is an enlarged sectional view showing an essential part of a third embodiment of the lens barrel according to the present invention.

FIG. 4 is an enlarged cross-sectional view showing the main parts of a fourth embodiment of the lens barrel according to the present invention.

FIG. 5 is an enlarged cross-sectional view showing the main parts of a fifth embodiment of the lens barrel according to the present invention.

[Explanation of symbols]

 11, 21, 31, 31, 41, 51 Lens barrel 11a, 21a, 31a, 41a, 51a Communication hole 12, 22, 32, 42, 52 Sealing member 23, 33, 43, 53 Drying agent 14, 24, 34, 44, 54 Internal space 15, 25, 35, 45, 55 External space 36 Seal member 47, 57 Filter member 58 Elastic member L1, L2 Lens

Claims (5)

[Claims] 1. A lens barrel having an internal space hermetically sealed between at least two lenses mounted on the barrel, the communication being formed in the barrel and communicating the internal space with the external space. A lens barrel, comprising: a hole; and a sealing member having a size in a range of approximately the wall thickness of the lens barrel portion and capable of being attached to and detached from the communication hole to seal the communication hole. 2. The lens barrel according to claim 1, wherein a desiccant for drying the internal space is inserted into the communication hole. 3. The lens barrel according to claim 1, wherein a desiccant for drying the internal space is inserted inside the sealing member. 4. The lens barrel according to claim 2 or 3, wherein the desiccant is replaceable. 5. The lens barrel according to claim 2, wherein a filter member having moisture permeability is provided between the internal space and the desiccant. Lens barrel.