JP2007034069A - Lens barrel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simplify the structure of a lens barrel and reliably shade the outside light. <P>SOLUTION: This lens barrel has a cam cylinder 30 having a cam groove and a ring flange 35 with a cam function by turning in the light axis direction and determining the aperture 35a to reduce its diameter toward the front in the light axis direction, a lens retainer cylinder 41 placed inside the cam cylinder 30 to retain the lens Gi with a follower pin 42 fitting in the cam groove, and a guide cylinder 60 arranged between the cam cylinder 30 and the lens retainer cylinder 41 to regulate the rotation of the lens retainer cylinder 41 and to define the guide groove 61 for guiding the follower pin 42 to the direction of the optical axis. The lens retainer cylinder 41 has a ring step 41c formed to reduce the diameter of the front cylinder 41a moving through the aperture 35a of the cam cylinder 30 smaller than the outer diameter of the rear cylinder 41b. In this configuration, the outside light is reflected at the ring step 41c and completely shaded, thus prevented from entering the inside. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a lens barrel that includes a plurality of tubes that are connected in a nested manner to move a lens in the optical axis direction, and more particularly, to a lens barrel that has a light blocking function that prevents intrusion of external light.

  As a conventional lens barrel, there are a fixed tube, a moving tube that holds the lens and is supported so as to be nested in and out of the fixed tube, and an outer peripheral surface of the moving tube that is fixed to the inner peripheral surface of the fixed tube. A plurality of light shielding ring members arranged in close contact with each other, and a plurality of light shielding ring members configured to prevent external light from entering through a gap between the movable cylinder and the fixed cylinder is known. (For example, refer to Patent Document 1).

  Other conventional lens barrels include a fixed tube, a first lens group and a second lens group that move relatively in the optical axis direction inside the fixed tube, and a first lens group and a second lens group. An annular light shielding member for preventing light leakage between the first lens group and the second lens group when the first lens group and the second lens group approach each other. There is known one configured to prevent external light from entering through a gap around the second lens group (see, for example, Patent Document 2).

JP 7-225332 A Japanese Patent Laid-Open No. 11-84198

By the way, in the above-mentioned conventional lens barrel, the light shielding ring member shields light while contacting the outer peripheral surface of the moving cylinder. Therefore, the light shielding ring member generates a frictional force and the moving cylinder moves smoothly. There was a problem that the operation time could not be increased. Moreover, since the light-shielding ring member is formed as a dedicated part, it has been a factor that increases the cost.
In the other conventional lens barrel, when the light shielding member provided behind the first lens group approaches the lens of the first lens group when the first lens group and the second lens group approach each other. Since light is engaged by engaging from behind, light cannot be shielded when the first lens group and the second lens group are relatively separated from each other. Further, since the light shielding member is formed in a special shape so as to be elastically deformed, it is difficult to manufacture and causes a cost increase.

  The present invention has been made in view of the above-described problems of the prior art, and the object of the present invention is to have a simple structure and can be shielded from light while facilitating smooth operation and the like. Another object of the present invention is to provide a lens barrel that can be manufactured at a low cost without using dedicated parts.

The lens barrel of the present invention has a cam groove having a cam groove that exerts a cam action in the optical axis direction by rotation and an annular flange portion that defines an opening having a reduced diameter at the front end in the optical axis direction, and is disposed inside the cam barrel. A lens holding cylinder having a follower pin that holds the lens and engages the cam groove, and a guide that is disposed between the cam cylinder and the lens holding cylinder to guide the follower pin in the optical axis direction so as to restrict the rotation of the lens holding cylinder. A lens barrel having a guide tube having a groove, wherein the lens holding tube is formed so that the outer peripheral surface of the front tube portion through which the opening of the cam tube is inserted is smaller in diameter than the outer peripheral surface of the rear tube portion. It is characterized by having an annular step portion.
According to this configuration, the lens holding cylinder moves in the optical axis direction by receiving the cam action by the cam groove while the follower pin is guided in the optical axis direction by the guide groove of the guide cylinder. At this time, the lens holding cylinder has a shape in which the diameter of the front cylinder part through which the opening of the annular flange part provided in the cam cylinder is reduced and the diameter of the rear cylinder part is increased through the annular step part, External light that has entered through the gap between the opening of the annular flange and the lens holding cylinder (the gap necessary for obtaining relative movement) is reflected and actively blocked by this annular step. Intrusion into the interior is reliably prevented. In this way, since it is possible to shield light by simply providing an annular stepped portion integrally with the lens holding cylinder instead of providing a dedicated light shielding member, the structure can be simplified, the number of parts can be reduced, etc. There is no sliding resistance due to such a light shielding member, and a smooth driving operation can be obtained.

In the above configuration, the annular stepped portion may be configured to be provided on the front side in the optical axis direction in the vicinity of the follower pin.
According to this configuration, since the guide groove of the guide cylinder into which the follower pin is inserted extends in the optical axis direction, there is a possibility that external light may enter through the guide groove. By providing in the front in the optical axis direction, it is possible to reliably shield external light entering the rear from the guide groove by a synergistic effect of the light shielding action by the annular step portion and the light shielding action by the follower pin.

The said structure WHEREIN: The structure by which the opening of an annular flange part is formed in the internal diameter smaller than the outer diameter of the outer peripheral surface of the rear cylinder part of a lens holding cylinder is employable.
According to this configuration, when viewed from the front in the optical axis direction, the opening (inner peripheral edge) of the annular flange portion of the cam cylinder overlaps with the region of the annular stepped portion of the lens holding cylinder. Since it is located between the outer peripheral surface of the front cylinder part and the outer peripheral surface of the rear cylinder part, the external light that has passed through the gap between the annular flange part and the lens holding cylinder is reflected more positively by the annular step part. Can be shielded more reliably.

In the above configuration, a configuration in which a plurality of lens groups are arranged on the cam cylinder from the front to the rear in the optical axis direction, and the lens holding cylinder is included in the front lens group can be adopted.
According to this configuration, since the lens holding cylinder having the annular step portion is included in the foremost lens group positioned in the forefront (most object side), the most upstream side of the path through which the external light enters the lens barrel Thus, it is possible to reliably block outside light.

  According to the lens barrel having the above configuration, it is possible to reliably prevent the intrusion of external light while achieving the simplification of the structure and the smooth operation of the lens holding cylinder. In addition, since the annular step portion that performs a light-shielding action is integrally formed on the lens holding cylinder, no dedicated parts are required, and cost reduction can be achieved.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, exemplary embodiments of the invention will be described with reference to the accompanying drawings.
1 to 7 show an embodiment of a lens driving apparatus incorporating a lens barrel according to the present invention. FIG. 1 is a front view of the apparatus, FIG. 2 is a sectional view of the apparatus, and FIG. FIG. 4 is a partially enlarged sectional view showing a part of a lens barrel, FIG. 5 is a partially sectional view showing a driving mechanism of the lens holding cylinder, and FIGS. 6 and 7 are sectional views of the apparatus.

  As shown in FIGS. 1, 2, 5 to 7, this apparatus includes a base 10 to which a glass filter 11, a CCD 12 as an imaging device and the like are attached, a fixed cylinder 20 fixed to the base 10, and a fixed cylinder 20. The first lens group 40, the second lens group 50, and the first lens group 40 supported so as to be movable in the optical axis direction L inside the cam cylinder 30, respectively. And a guide cylinder 60 that guides in the optical axis direction L while restricting the rotation of the second lens group 50, a drive mechanism 70 that drives the cam cylinder 30, a drive mechanism 80 included in the first lens group 40, and the like.

  The base 10 is formed of a resin material into a substantially rectangular shape, and includes a coupling portion 10a for coupling the fixed cylinder 20, a rectangular recess 10b for attaching the glass filter 11, a rectangular recess 10c for attaching the CCD 12, and the like.

  As shown in FIGS. 2, 6, and 7, the fixed cylinder 20 is formed in a cylindrical shape with a resin material so as to have an axis in the optical axis direction L, and is fixed to the base 10. Three cam grooves 21 (a part of which is shown in the figure) are arranged on the inner peripheral surface 20a of the fixed cylinder 20 at regular intervals (about 120 degrees) in the circumferential direction and exert a cam action on three follower pins 31 described later. (Omitted) is formed.

  As shown in FIGS. 1, 2, and 3, the cam cylinder 30 is formed in a cylindrical shape from a resin material, and is arranged coaxially in a nested manner inside the fixed cylinder 20. The cam cylinder 30 includes three follower pins 31 arranged at equal intervals (approximately every 120 degrees) in the circumferential direction on the outer circumferential surface 30a, an arc-shaped rack portion 32 to which a rotational driving force is transmitted from the outside, and the like. 2, 6, and 7, on the surface 30 b, three cam grooves 33 that cam the first lens group 40 in the optical axis direction L, and cam in the second lens group 50 in the optical axis direction L Three cam grooves 34 that act are provided, and an annular flange portion 35 that defines a reduced-diameter circular opening 35a is provided at the front end in the optical axis direction L.

As shown in FIGS. 2, 5, 6, and 7, the first lens group 40 is provided in the lens holding cylinder 41 and the lens holding cylinder 41 formed in a substantially cylindrical shape by a resin material, and is formed in the cam groove 33. Three follower pins 42 to be inserted, a lens frame 43 that is movably connected to the lens holding cylinder 41, holds the lens G1, a drive mechanism 80 that drives the lens frame 43 relative to the lens holding cylinder 41, and the like It has.
The first lens group 40 moves forward and backward in the optical axis direction L when the cam cylinder 30 rotates and the cam groove 33 exerts a cam action on the follower pin 42. Further, when the drive mechanism 80 is activated, the lens frame 43 moves forward and backward relative to the lens holding cylinder 41 in the optical axis direction L.

Here, as shown in FIGS. 2, 3, and 4, the lens holding cylinder 41 can be inserted through the opening 35 a defined by the annular flange portion 35 of the cam cylinder 30 (can be projected and retracted with respect to the cam cylinder 30). ) The front cylinder part 41a, the rear cylinder part 41b following it, and the annular step part 41c interposed between the front cylinder part 41a and the rear cylinder part 41b are provided.
As shown in FIG. 4, the front cylindrical portion 41a is reduced in diameter so that the outer peripheral surface forms a predetermined gap D1 in the radial direction with the opening 35a of the annular flange portion 35, that is, smaller than the inner diameter of the opening 35a. It is formed so as to have an outer diameter.
As shown in FIG. 4, the rear cylinder portion 41b has an outer diameter that is substantially the same as the inner diameter of the opening 35a so that the outer peripheral surface thereof hardly forms a gap in the radial direction with the opening 35a of the annular flange portion 35. The diameter is increased.
As shown in FIG. 4, the annular step portion 41 c is formed at the boundary between the front cylinder portion 41 a and the rear cylinder portion 41 b, and is positioned in the vicinity of the follower pin 42 and on the front side in the optical axis direction L. .

That is, the lens holding cylinder 41 has a shape in which the diameter of the front cylinder part 41a inserted through the opening 35a of the annular flange part 35 provided in the cam cylinder 30 is reduced, and the diameter of the rear cylinder part 41b is increased via the annular step part 41c. It has become. Therefore, external light entering from the gap D1 (gap required for obtaining relative movement) between the opening 35a of the annular flange portion 35 and the lens holding cylinder 41 is caused by the surface of the annular step portion 41c. The light is reflected and actively shielded, and the intrusion into the inside is surely prevented.
In particular, here, since the annular step portion 41c is provided on the front side in the optical axis direction L in the vicinity of the follower pin 42, even if the follower pin 42 is inserted into a guide groove 61 of the guide cylinder 60 described later, the annular step portion 41c is provided. Due to the synergistic effect of the light shielding action by the portion 41 c and the light shielding action by the follower pin 42, it is possible to reliably shield outside light that is about to enter the rear from the guide groove 61.

  In addition, as described above, since a dedicated light shielding member is not provided as the light shielding structure, but only the annular stepped portion 41c is integrally provided in the lens holding cylinder 41, the structure is simplified, the number of parts is reduced, and the like. In addition, there is no sliding resistance due to the light shielding member as in the prior art, and a smooth driving operation can be obtained.

The lens frame 43 holds the lens G1 and is supported so as to be movable relative to the lens holding cylinder 41 in the optical axis direction L.
As shown in FIG. 5, the lens frame 43 includes a cylindrical portion 43a that is movably supported by the lens holding cylinder 41, a connecting portion 43b that extends from the cylindrical portion 43a and is slidably connected to a guide shaft 87 described later. A nut receiving portion 43c for receiving a nut 85 to be described later, a latching piece 43d, and the like are provided.

  As shown in FIG. 5, the driving mechanism 80 is held inside the lens holding cylinder 41, and is a stepping motor 81, a driving gear 82, a gear that is rotatably supported by the lens holding cylinder 41 and meshes with the driving gear 82. 83, a lead screw 84 that rotates integrally with the gear 83, a nut 85 that is screwed to the lead screw 84 and abutted with the nut receiving portion 43c, a latch piece 43d of the lens frame 43, and a lens holding cylinder 41 A coil spring 86 hooked between the stop pieces 41d, a guide shaft 87 that is inserted into the connecting portion 43b and guides the lens frame 43 in the optical axis direction L, and the like are provided.

  That is, when the stepping motor 81 rotates, the lead screw 84 rotates through the drive gear 82 and the gear 83, and the nut 85 is screwed. Then, since the nut receiving portion 43c is always in contact with the nut 85 by the urging force of the coil spring 86, the lens frame 43 moves forward or backward in the optical axis direction L following the nut 85 to perform focusing. It has become.

  2, 6, and 7, the second lens group 50 is formed in a substantially cylindrical shape by a resin material, is formed on the lens frame 51 that holds the lens G <b> 2, the lens frame 51, and is inserted into the cam groove 34. Three follower pins 52 and a shutter unit 53 fixed to the lens frame 51 behind the lens G2. The second lens group 50 moves forward and backward in the optical axis direction L as the cam cylinder 30 rotates and the cam groove 34 exerts a cam action.

As shown in FIGS. 2, 4, 6, and 7, the guide tube 60 is disposed between the first lens group 40 and the second lens group 50 and the cam tube 30. The second lens group 50 is guided to reciprocate in the optical axis direction L while restricting the rotation of the second lens group 50.
That is, the guide tube 60 receives three follower pins 42 of the lens holding tube 41 and guides them in the optical axis direction L, and three guide grooves 61 receives the follower pins 52 of the lens frame 51 and guides them in the optical axis direction L. 62, a latching claw 63 latched in an annular groove formed in the inner peripheral surface 30b of the cam cylinder 30, a fixing flange 64 formed at the rear end portion, and the like.
Here, the guide grooves 61 and 62 are formed in a long hole shape that is notched and extends in the optical axis direction L, but the groove shape is defined in cooperation with the inner peripheral surface 30 b of the cam cylinder 30. To do.

  The guide tube 60 is fitted to the inner peripheral surface 30b of the cam tube 30 by the latching claw 63 and the flange 64, but the projection (not shown) formed on the flange 64 is formed on the fixed tube 20. It is inserted in the fixed cylinder 20 so that it may not be rotated by being inserted into a long groove extending in the direction L. Therefore, when the cam cylinder 30 rotates, the guide groove 61 of the guide cylinder 60 guides the follower pin 42, which is cammed by the cam groove 33, so that the follower pin 42 can reciprocate only in the optical axis direction L. 62 guides the follower pin 52, which is cammed by the cam groove 34, so as to reciprocate only in the optical axis direction L.

As shown in FIG. 1, the drive mechanism 70 includes a DC motor 71 fixed to the base 10, a gear train including a gear 72 that meshes with the rack portion 32, and the like. To communicate.
That is, when the DC motor 71 rotates, the cam cylinder 30 rotates relative to the fixed cylinder 20 via a gear train including the gear 72. The first lens group 40 and the second lens group 50 are extended (moved forward) or retracted (moved backward) in the optical axis direction L, respectively, from the retracted position at the time of non-photographing shown in FIG. The zooming is performed so that a wide range of photographing can be performed by moving from the wide-angle end position shown in FIG. 6 to the telephoto end photographing position shown in FIG.

  Next, a general operation when the lens driving device having the lens barrel described above is mounted on a digital camera will be described. First, the first lens group 40, the second lens group 50, and the cam cylinder when not photographing. As shown in FIG. 2, 30 is a retracted position retracted backward in the optical axis direction L.

  When the cam cylinder 30 is rotated by the drive mechanism 70 from the retracted position, the follower pin 31 is guided and moved by the cam groove 21, and the cam cylinder 30 is advanced toward the front in the optical axis direction L. Further, the follower pins 42 and 52 are guided to the cam grooves 33 and 34, respectively, by the rotation of the cam cylinder 30, and the first lens group 40 and the second lens group 50 are moved from the wide-angle end photographing position shown in FIG. The zooming operation to the telephoto end shooting position shown is performed. On the other hand, the driving mechanism 80 moves the lens frame 43 relative to the lens holding cylinder 41 in the first lens group 40 to perform a focusing operation according to the position of the second lens group 50.

During this series of operations, the external light that has entered through the gap D1 between the lens holding cylinder 41 and the cam cylinder 30 is reflected by the annular step portion 41c (surface) provided in the lens holding cylinder 41 and actively The light is shielded from the light and the intrusion into the inside is surely prevented.
Here, among the plurality of lens groups (the first lens group 40 and the second lens group 50) arranged from the front to the rear in the optical axis direction L on the inner side of the cam cylinder, the first lens located at the foremost position. By providing an annular stepped portion 41c having a light shielding function with respect to the lens holding cylinder 41 included in the group 40 (the frontmost lens group), on the most upstream side of the path through which external light enters the lens barrel, External light can be reliably shielded.

  FIG. 8 shows another embodiment of a lens barrel according to the present invention. In this embodiment, as shown in FIG. 8, the lens holding cylinder 41 ′ is further reduced in diameter by the front cylinder part 41 a ′ inserted through the opening 35 a ′ of the annular flange part 35 provided in the cam cylinder 30. The rear cylinder part 41b is formed in a shape in which the diameter is enlarged through an annular stepped part 41c 'that has become wide. Further, the opening 35a ′ of the annular flange portion 35 is structurally required to obtain the relative clearance D1 (relative movement between the lens holding tube 41 ′ (the outer peripheral surface of the front tube portion 41a ′) as described above. The inner diameter is smaller than that of the above-described opening 35a so as to define a gap).

That is, in other words, the step size D2 due to the difference between the outer diameter of the front cylinder portion 41a ′ and the outer diameter of the rear cylinder portion 41b is larger than the gap D1 between the opening 35a ′ and the front cylinder portion 41a ′. The opening 35a ′ of the annular flange portion 35 is formed with an inner diameter smaller than the outer diameter of the outer peripheral surface of the rear cylinder portion 41b of the lens holding cylinder 41 ′.
Thereby, the external light that has entered from the gap D1 is reflected by the wide surface of the annular step portion 41c ′ and is actively shielded, and the intrusion to the inside is more reliably prevented.

In the above-described embodiment, the first lens group 40 and the second lens group 50 are shown as the plurality of lens groups that are moved in the optical axis direction L by the cam cylinder 30, but in the configuration including one lens group, or The present invention may be employed in a configuration including three or more lens groups.
Moreover, in the said embodiment, although the case where annular level | step-difference part 41c, 41c 'was provided in the front vicinity of the follower pin 42 was shown, it is not limited to this, It provides in the position away from the follower pin 42 ahead May be.
In the above-described embodiment, the case where the annular stepped portions 41c and 41c ′ are provided in the lens holding cylinder 41 included in the lens group 40 positioned in the foremost position in the optical axis direction L has been described. Even if an annular step portion is provided for the lens holding cylinder included in the lens group located at the rear side, it is possible to prevent external light from entering the CCD 12 further arranged at the rear side.

  As described above, since the lens barrel of the present invention can surely block outside light while guaranteeing smooth operation, it can be mounted on a digital still camera, a digital video camera or the like. In addition, the present invention can be similarly applied to a silver salt film type camera.

It is a front view which shows one Embodiment of the lens drive device incorporating the lens barrel which concerns on this invention. It is sectional drawing which shows the state which the lens-barrel of the apparatus shown in FIG. 1 retracted. 1 shows a lens holding tube of a first lens group that forms a part of a lens barrel, in which (a) is a front view and (b) is a side view. It is a partial expanded sectional view which shows the cyclic | annular level | step-difference part provided in the lens holding cylinder. It is a fragmentary sectional view which shows the drive mechanism contained in the 1st lens group which makes a part of lens barrel. It is sectional drawing which shows the state which the lens-barrel of the apparatus shown in FIG. 1 extended to the wide-angle end imaging position. It is sectional drawing which shows the state which the lens-barrel of the apparatus shown in FIG. 1 extended to the telephoto end imaging position. It is a partial expanded sectional view which shows other embodiment of the lens-barrel which concerns on this invention.

Explanation of symbols

L Optical axis direction G1, G2 Lens 10 Base 11 Glass filter 12 CCD
20 fixed cylinder 21 cam groove 30 cam cylinder 30b inner peripheral surface 31 follower pins 33, 34 cam groove 35 annular flange portions 35a, 35a ′ opening 40 first lens group (front lens group)
41 Lens holding cylinders 41a, 41a 'Front cylinder part 41b Rear cylinder parts 41c, 41c' Annular step 42 Follower pin 43 Lens frame 50 Second lens group 51 Lens frame 52 Follower pin 60 Guide cylinder 61, 62 Guide groove 70 Drive mechanism 71 DC Motor 80 Drive mechanism 81 Stepping motor

Claims (4)

A cam cylinder having a cam groove that exerts a cam action in the optical axis direction by rotation and an annular flange portion that defines an opening having a reduced diameter at the front end in the optical axis direction, disposed inside the cam cylinder, and holding a lens A lens holding cylinder having a follower pin that engages with the cam groove, and a guide groove that is arranged between the cam cylinder and the lens holding cylinder to guide rotation of the lens holding cylinder and guides the follower pin in the optical axis direction. A lens barrel having a guide tube having
The lens holding cylinder has an annular step portion that is formed so that the outer peripheral surface of the front cylindrical portion that is inserted through the opening of the cam cylinder is smaller in diameter than the outer peripheral surface of the rear cylindrical portion.
Lens barrel characterized by that The annular step portion is provided on the front side in the optical axis direction in the vicinity of the follower pin.
The lens barrel according to claim 1. The opening of the annular flange portion is formed with an inner diameter smaller than the outer diameter of the outer peripheral surface of the rear cylinder portion of the lens holding cylinder.
The lens barrel according to claim 1 or 2, wherein In the cam cylinder, a plurality of lens groups are arranged from the front to the rear in the optical axis direction,
The lens holding cylinder is included in the front lens group.
The lens barrel according to claim 1, wherein the lens barrel is a lens barrel.

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