JP2006243426A - Lens barrel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens barrel in which lenses are easily fitted and its manufacturing cost is restrained. <P>SOLUTION: A spiral air escape groove 12 is formed on the internal circumferential face 8a of the cylindrical part 8 of the lens barrel 2 by cutting work. Since the cutting work for the air escape groove 12 follows cutting work for the lens barrel 2, it can be formed in a short time. As shown in Fig.4(B), air between the first lens 3 and the second lens 4 is compressed by the insertion of the second lens 4. However, the air escapes from an opening 2b in the rear end through the air escape groove 12. This solves the problem in which the second lens 4 is pushed back and cannot be inserted easily, the problem in which the second lens 4 is moved after positioned, and also solves similar problems. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a lens barrel in which a plurality of lenses are sequentially inserted and incorporated.

  In a lens barrel used for an optical device such as a camera, it is important to position the lens to be incorporated with high accuracy in order to maintain optical performance. In particular, when a lens system with high eccentricity sensitivity is incorporated, higher accuracy is required.

  The lens to be incorporated has an outer diameter of the lens that is substantially the same as the inner diameter of the lens barrel in order to avoid displacement in the radial direction. For this reason, when a plurality of lenses having the same diameter are incorporated adjacent to each other in the lens barrel, when the lenses are inserted one by one when the lenses are assembled, the gap between the first inserted lens and the later inserted lens is reduced. The air is compressed without escape. This compressed air pushes back a lens to be inserted later to make it difficult to insert, and also remains after the lens is positioned and moves the lens to change the lens interval. In addition, the compressed air may cause the lens to be caught on the inner peripheral wall of the lens barrel, causing an inclination within a minute clearance and degrading the performance of the lens group.

  Conventionally, in order to avoid a problem caused by compressed air, an assembly jig 100 as shown in FIG. 6 is generally used. The assembly jig 100 includes a cradle 101 and a lens holding frame 102. As shown in FIG. 6A, after the lenses 103 and 104 are once inserted and held in order in the lens holding frame 102, the lens barrel placed on the upper surface of the lens holding frame 102 as shown in FIG. 6B. 105 is pushed down, and the lenses 103 and 104 are transferred from the lens holding frame 102 to the lens barrel 105.

  However, the above-mentioned assembly jig is limited in use when all the lenses to be incorporated are composed of lenses having the same diameter, and when the lens is composed of lenses having different diameters, there is a step on the inner peripheral wall of the lens barrel. Because it was, it could not be used.

  In order to avoid the problem caused by the compressed air, it is conceivable to form a through hole in the lens barrel in the radial direction (that is, from the outer peripheral surface to the inner peripheral surface) and let the compressed air escape from the through hole. However, in this case, a slight distortion occurs in the lens barrel, and the manufacturing cost increases.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a lens barrel in which a lens can be easily incorporated and the manufacturing cost is reduced.

  The present invention relates to a lens barrel in which a plurality of lenses are sequentially inserted and incorporated, and an air escape groove for releasing air compressed between the lenses when the lens is inserted is formed on an inner peripheral surface.

  The air escape groove is preferably formed in a spiral shape by cutting. Moreover, it is preferable that the one end part of the said air escape groove | channel is formed in the end winding shape.

  The present invention is effective when lenses having different diameters are incorporated and at least two lenses having the same diameter are incorporated.

  According to the lens barrel of the present invention, since the air escape groove for releasing the air compressed between the lenses when the lens is inserted is formed on the inner peripheral surface, the compressed air between the lenses escapes from the air escape groove. Accordingly, the lens can be easily inserted and incorporated, and the lens is not moved after the lens is positioned, and the lens can be positioned with high accuracy.

  Since the air relief groove is formed in a spiral shape by cutting, it can be formed in a short time by a lathe, and the manufacturing cost can be suppressed. In particular, when the lens barrel is formed by cutting with a lathe, following the process of cutting the lens barrel, the lens barrel continues to rotate and air is released without changing the cutting tool. Since it is possible to shift to the process of cutting the groove, it does not take time. The air escape groove may have an arbitrary shape, and may be, for example, a straight line formed in parallel with the optical axis of the lens barrel.

  When the air relief groove is cut by a lathe, if the spiral groove is formed once after forming the end winding groove, the groove depth of the end winding groove and the end winding groove Since the position in the optical axis direction can be accurately set, the air escape groove can be formed accurately. Processing results do not vary between products.

  An embodiment of the lens barrel of the present invention is shown in FIG. The lens barrel 2 is used for an optical device such as a camera or a liquid crystal projector.

  A first lens 3, a second lens 4, and a third lens 5 are incorporated in the lens barrel 2. The first lens 3 is held on the inner peripheral surface 6 a of the step portion 6 formed at the front end portion (right end portion in the figure) of the lens barrel 2. The outer diameter of the first lens 3 is substantially the same as the inner diameter of the step portion 6. The first lens 3 is positioned in the optical axis direction with the front surface in contact with the stepped portion 6 and the rear surface in contact with the presser ring 7. The presser ring 7 is made of rubber, and the outer diameter of the presser ring 7 is substantially the same as the inner diameter of the tube portion 8 of the lens barrel 2.

  The second lens 4 and the third lens 5 are held on the inner peripheral surface 8 a of the tube portion 8 of the lens barrel 2. The outer diameters of the second lens 4 and the third lens 5 are substantially the same as the inner diameter of the cylindrical portion 8. The second lens 4 is positioned in the optical axis direction behind the first lens 3 with the front surface in contact with the presser ring 7 and the rear surface in contact with the presser ring 9. The third lens 5 is positioned in the optical axis direction behind the second lens 4 with the front surface in contact with the presser ring 9 and the rear surface in contact with the presser ring 10. The presser rings 9 and 10 are made of rubber like the presser ring 7 described above, and the outer diameters of the presser rings 9 and 10 are substantially the same as the inner diameter of the cylindrical portion 8. A front end opening 2a is formed at the front end of the lens barrel 2, and a rear end opening 2b is formed at the rear end.

  An air escape groove 12 is formed on the inner peripheral surface 8 a of the tube portion 8 of the lens barrel 2. As will be described in detail later, the air escape groove 12 allows the air between the first lens 3 and the second lens 4 to escape to the outside when the second lens 4 is inserted into the lens barrel 2, and the third This is for releasing air between the second lens 4 and the third lens 5 to the outside when the lens 5 is inserted into the lens barrel 2.

  As shown in FIG. 2, the front end portion of the air escape groove 12 is an end turn portion 12 a formed in a end turn shape. The end turn part 12a is located slightly behind the step part 6, and is formed to draw a circle (or arc) in a plane perpendicular to the optical axis. The air escape groove 12 is formed in a spiral shape behind the end turn part 12a. The groove depth, groove width, and pitch of the air escape groove 12 are not particularly limited.

  The lens barrel 2 is formed by cutting using a lathe. The lathe has a chuck 20 and a cutting tool 21 shown in FIG. The chuck 20 grips the object and rotates together with the object. The cutting tool 21 is movable in the optical axis direction and the radial direction, and cuts the object by applying the blade edge to the object. The feed amount of the cutting tool 21 is manipulated, and the lens barrel 2 is cut out by applying the cutting edge to the rotating object.

  The air relief groove 12 is cut after the lens barrel 2 is cut. The rotation of the lens barrel 2 is continued, and the cutting tool 21 is the same as that for cutting the lens barrel 2. The air relief groove 12 is cut by the following procedure.

  First, the cutting tool 21 is fed forward, and the cutting edge 21a is positioned at a predetermined position slightly away from the stepped portion 6. Next, the cutting tool 21 is moved in the radial direction, and the end winding part 12 a of the air escape groove 12 is formed on the inner peripheral surface 8 a of the cylindrical part 8 of the lens barrel 2. After forming the end turn part 12a, as shown in FIG. 3, the cutting bite 21 is sent backward to form the air escape groove 12 in a spiral shape. The air escape groove 12 is formed at the same depth in any region.

  Thus, since the process of cutting the air escape groove 12 is performed following the process of cutting the lens barrel 2, it can be formed in a short time, and the manufacturing cost can be suppressed.

  Below, the operation | movement which inserts and incorporates each lens 3, 4, 5 in the lens-barrel 2 is demonstrated using FIG. The lens is assembled with the lens barrel 2 fixed. First, as shown in FIG. 4A, the first lens 3 is inserted from the rear end opening 2b. The first lens 3 is slid on the inner peripheral surface 6 a of the step portion 6, and the first lens 3 is inserted to a position where it is locked to the step portion 6. Here, since the air in front of the first lens 3 escapes from the front end opening 2a of the lens barrel 2, the problem of compressed air does not occur. After inserting the first lens 3, the presser ring 7 is inserted to fix the first lens 3.

  Next, as shown to (B), the 2nd lens 4 is inserted from the rear-end opening 2b. The second lens 4 is slid on the inner peripheral surface 8 a of the cylindrical portion 8, and the second lens 4 is inserted to a position where it is locked to the presser ring 7. Here, the air between the first lens 3 and the second lens 4 is compressed, but this air escapes from the rear end opening 2 b through the air escape groove 12. For this reason, problems such as the second lens 4 being pushed back to make insertion difficult or the second lens 4 moving after positioning of the second lens 4 do not occur. After the second lens 4 is inserted, the presser ring 9 is inserted to fix the second lens 4.

  Finally, as shown in (C), the third lens 5 is inserted from the rear end opening 2b. When the third lens 5 is inserted, the air between the second lens 4 and the third lens 5 is compressed as in the case of the second lens 4, but this air passes through the air release groove 12. Since it escapes from the end opening 2b, the problem by compressed air does not arise. After the insertion of the third lens 5, the presser ring 10 is inserted to fix the third lens 5, and the incorporation of the lenses 3, 4, 5 is completed.

  In the above embodiment, the air escape groove is formed in a spiral shape, but the shape of the air escape groove is not limited to this and may be arbitrary. For example, as shown in FIG. 5, a straight air escape groove 30 parallel to the optical axis of the lens barrel 2 may be formed.

  In the above embodiment, the air relief groove is formed by cutting, but may be formed by other processing methods. Moreover, in the said embodiment, although the lens-barrel was formed by cutting, you may form by this other processing method.

  In the above embodiment, three lenses are incorporated in the lens barrel, but the number of lenses is not limited to this, and may be arbitrary. Moreover, the diameters of these lenses may be arbitrary.

  In the above embodiment, the air escape groove is not formed on the inner peripheral surface of the step portion formed in the lens barrel. However, when holding a plurality of lenses in the step portion, the air is also applied to the inner peripheral surface of the step portion. It is preferable to form a relief groove.

It is sectional drawing of the lens-barrel of the state which incorporated the lens of this invention. It is sectional drawing of the lens-barrel of the state which does not incorporate the lens. It is explanatory drawing explaining the cutting process of an air escape groove | channel. It is explanatory drawing explaining a lens incorporation operation | movement. It is sectional drawing of the lens barrel of another embodiment which formed the air escape groove | channel linearly. It is explanatory drawing explaining the lens incorporation operation | movement in the past.

Explanation of symbols

2 Lens barrel 3 First lens 4 Second lens 5 Third lens 6 Step portion 8 Tube portion 8a Inner peripheral surface 12, 30 Air escape groove 12a Seat winding portion

Claims (4)

In a lens barrel in which a plurality of lenses are sequentially inserted and incorporated,
1. A lens barrel characterized in that an air escape groove for releasing air compressed between lenses when a lens is inserted is formed on an inner peripheral surface.   The lens barrel according to claim 1, wherein the air escape groove is formed in a spiral shape by cutting.   The lens barrel according to claim 2, wherein one end portion of the air escape groove is formed in an end winding shape. 4. The lens barrel according to claim 1, wherein lenses having different diameters are incorporated, and at least two lenses having the same diameter are incorporated.

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