JP2010020191A - Zoom lens barrel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To miniaturize a zoom lens barrel. <P>SOLUTION: The zoom lens includes: a lens optical system comprising a first lens group 60, a second lens group 30, a third lens group 40 and a fourth lens group 70 arranged in order in an optical axis direction in a housing 10; and a drive mechanism 90 driving the lens groups included in the lens optical system. The first lens group 60 and the fourth lens group 70 are fixed in the housing 10, and the second lens group 30 and the third lens group 40 are supported to be movable in the optical axis direction. The drive mechanism 90 includes: a first drive mechanism 91 performing focus drive and correction drive of the second lens group 30; and a second drive mechanism 92 performing zoom drive of the third lens group 40. Thus, a moving amount of the lens optical system in the optical axis direction as a whole is suppressed while securing a prescribed magnification, consequently, dimension of the housing in the optical axis direction is shortened, and the miniaturization of the zoom lens barrel is achieved. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a zoom lens barrel applied to a small digital camera (mobile camera) mounted on a cellular phone or the like, and more particularly to a zoom lens barrel having a zoom function, a focus function, and a correction function.

A conventional zoom lens barrel includes a zoom function, a focus in a four-group configuration including a first lens group, a second lens group, a third lens group, and a fourth lens group, which are sequentially arranged in the optical axis direction. In order to provide a mechanism and a correction function, one that drives three lens groups relatively in the optical axis direction is known.
In such a zoom lens barrel, three drive mechanisms (actuators) are required to drive the three lens groups, and it is difficult to reduce the size of the zoom lens barrel.

Other zoom lens barrels include a prism disposed in the casing adjacent to the photographing window, a first lens group fixed in the casing behind the prism, and in the casing behind the first lens group. A second lens group movably disposed, a third lens group movably disposed in the casing behind the second lens group, a fourth lens group fixed in the casing behind the third lens group, and a fourth lens group An image pickup device fixed to the housing behind the lens group, a first drive mechanism and a second drive mechanism for driving the second lens group and the third lens group, respectively. The second lens group is provided by the first drive mechanism. It is known that the zoom lens is driven and the third lens group is zoom-driven and focus-driven by a second driving mechanism (see, for example, Patent Document 1).
In this zoom lens barrel, since the two lens groups are moved in the four-group configuration, the number of driving mechanisms is two as compared with the case where the three lens groups are moved, but the second lens group is zoom-driven. The stroke (the amount of movement in the optical axis direction) that moves at that time is large, and it has been difficult to reduce the size and size of the zoom lens barrel in the optical axis direction.

JP 2004-145019 A

  The present invention has been made in view of the above circumstances, and its object is to simplify the structure, improve the assembly workability, and ensure the assembly while ensuring the zoom function, the focus function, and the correction function. A zoom lens barrel suitable for digital cameras (mobile cameras) mounted on mobile phones, etc., which can improve mounting accuracy, increase the optical axis alignment accuracy, shorten the optical axis direction, reduce size, etc. It is to provide.

The zoom lens barrel of the present invention includes a housing extending in the optical axis direction, and a first lens group, a second lens group, a third lens group, and a fourth lens group, which are sequentially arranged in the optical axis direction within the housing. A lens optical system, and a drive mechanism for driving a lens group included in the lens optical system. The first lens group and the fourth lens group are fixed to the housing, and the second lens group and the third lens group are The zoom lens barrel is movably supported in the optical axis direction, and the driving mechanism includes a first driving mechanism that drives the second lens group for focus driving and correction, and a second driving mechanism that drives the third lens group for zooming. It is characterized by including.
According to this configuration, in the zoom lens barrel having the four-group configuration, the first lens group and the fourth lens group are fixed, the third lens group is zoom-driven by the second driving mechanism, and the second lens group is the first lens group. Since the focus drive and correction drive are performed by the drive mechanism, the movement amount in the optical axis direction of the lens optical system as a whole can be suppressed while ensuring a predetermined magnification. As a result, the dimension of the housing in the optical axis direction can be reduced. The zoom lens barrel can be reduced in size.

In the above configuration, the third lens group may employ a configuration in which the refractive power is set larger than that of the first lens group, the second lens group, and the fourth lens group.
According to this configuration, by increasing the refractive power of the zoom-driven third lens group, it is possible to reduce the amount of movement of the third lens group while ensuring a predetermined magnification, and to reduce the size of the zoom lens barrel. Can be achieved.

In the above configuration, the third lens group includes a lens frame and a plurality of lenses held by the lens frame, and the lens arranged at the forefront among the plurality of lenses is provided so as to be aligned with the lens frame. The configuration can be adopted.
According to this configuration, by increasing the refractive power of the third lens group, the sensitivity of positional deviation with respect to the optical axis becomes sensitive, but the lens positioned in front of the third lens group is the lens frame (other lens). Therefore, by aligning the front lens and fixing it to the lens frame, it can be aligned with high accuracy on the optical axis, and the desired optical characteristics can be obtained. Obtainable.

In the above configuration, the third lens group includes a biconvex front lens, a meniscus intermediate lens that is convex on the object side, and a meniscus rear lens that is convex on the object side. Can be adopted.
According to this configuration, the plurality of lenses included in the third lens group include a biconvex front lens, a meniscus intermediate lens convex on the object side, and a meniscus rear lens convex on the object side. Therefore, a predetermined magnification can be obtained with a strong refractive power, that is, a short movement amount, while ensuring desired optical characteristics.

In the above configuration, a configuration may be employed in which a bending element that bends incident light and guides it to the lens optical system is disposed in front of the first lens group.
According to this configuration, it is possible to achieve downsizing or the like in the zoom lens barrel in which the optical axis (optical path) passes through a bending element such as a prism and is bent at, for example, 90 degrees and guided to the lens optical system. Thus, it is possible to obtain a zoom lens barrel suitable for being mounted on a mobile phone or the like that is required to be reduced in size and thickness.

  According to the zoom lens barrel having the above configuration, while ensuring the zoom function, the focus function, and the correction function, the structure is simplified, the assembly workability is improved, the assembly accuracy is improved, and the optical axis alignment of the lens is high. A zoom lens barrel suitable for a digital camera (mobile camera) or the like mounted on a mobile phone or the like can be obtained because accuracy, shortening of the optical axis direction, miniaturization, and the like can be achieved.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, exemplary embodiments of the invention will be described with reference to the accompanying drawings.
1 to 9 show an embodiment of a zoom lens barrel according to the present invention. FIG. 1 is a perspective view showing a state in which a zoom lens barrel M is mounted on a mobile phone P. FIG. 3 is an exploded perspective view of the zoom lens barrel, FIG. 4 is a perspective view showing a housing of the zoom lens barrel, and FIGS. 5 and 6 are cross-sectional views showing the inside of the housing. 7 is a cross-sectional view of the zoom lens barrel on the plane including the optical axis, FIG. 8 is a cross-sectional view showing the third lens group of the lens optical system, and FIG. 9 is a lens optical system included in the zoom lens barrel. It is sectional drawing explaining operation | movement of a type | system | group.
Here, as shown in FIG. 1, the zoom lens barrel M is built in a lid P1 having a monitor of the mobile phone P, and the optical axis L of the subject light is perpendicular to the outer surface of the lid P1. After entering, it is bent at a right angle and is formed so as to enter an image pickup device such as a CCD connected to the rear side of the zoom lens barrel M.

  As shown in FIGS. 2 and 3, the zoom lens barrel M includes a housing 10 that defines an outer contour, guide shafts 21 and 22, a rotation stop guide shaft 23, and a front movable lens group as a second lens group. 30, a rear movable lens group 40 as a third lens group, a coil spring 50 that pulls the front lens group 30 and the rear lens group 40 together in the optical axis direction L, a front fixed lens group 60 as a first lens group, A rear fixed lens group 70 as a four lens group, a prism 80 as a bending element, a drive mechanism 90, a first detection sensor 101 for detecting the position of the front movable lens group 30 in the optical axis direction L, and a rear movable lens group 40 The second detection sensor 102 that detects the position of the lens in the optical axis direction L, the cover 110 that covers the opening of the housing 10, and the prism 80 are pressed against the housing 10. Holding cover 120 is constant, and a flexible wiring board 130 and the like.

  That is, in the housing 10, a fixed first lens group (front fixed lens group 60) and a second lens movably supported in the optical axis direction L behind the fixed bending element (prism 80). A lens optical system including a group (front movable lens group 30), a third lens group (rear movable lens group 40), and a fixed fourth lens group (rear fixed lens group 70) is arranged, and an image is captured behind the lens optical system. Elements are arranged.

As shown in FIGS. 3 and 4, the casing 10 is a cavity having a substantially rectangular cross section made of a resin material and is formed to extend in the optical axis direction L, and is positioned in front of the optical axis direction L. Formed excluding the front wall 11, the rear wall 12 located behind the optical axis direction L, the side walls 13 and 14 facing the direction perpendicular to the optical axis direction L, and the side walls facing the direction perpendicular to the optical axis direction L The openings 15 and 16 are formed, and an extension wall 17 extending from the front wall 11 in a substantially triangular shape is provided.
Further, as shown in FIGS. 2 to 4, the housing 10 includes a front annular fixing portion 11a, three fitting holes 11b, screws, and the like, which can insert and fix the front fixed lens group 60 from the front in the optical axis direction L. After the hole 11c, the positioning protrusion 11d, the recess 11e for attaching the first detection sensor 101, the recess 11f for fitting a part of the drive mechanism 90, and the rear fixed lens group 70 can be inserted and fixed from the rear in the optical axis direction L. Side annular fixing portion 12a, three fitting holes 12b, screw holes 12c, positioning projection 12d, concave portion 12e for attaching second detection sensor 102, concave portion 12f for fitting a part of drive mechanism 90, substantially U continuous with concave portion 12f A letter-shaped flange portion 12g, a substantially rectangular recess 12h that accommodates an image sensor such as a CCD, latching claws 12i and 13a for latching the cover 110, and a positioning projection 1 for positioning the drive mechanism 90 a, has a circular hole 14b through which screws B, screw holes 17a, 4 one engaging claw 17b for hooking the holding cover 120, the positioning portion 17c and the like for positioning the prism 80.

As shown in FIG. 4, the three fitting holes 11b and the three fitting holes 12b are inserted into the guide shafts 21 and 22 and the rotation stop guide shaft 23 from the rear in the optical axis direction L, respectively. (The front end is fitted into the fitting hole 11b and the rear end is fitted into the fitting hole 12b).
Thus, since the housing | casing 10 fits and fixes the both ends of the three guide shafts 21,22,23, the three guide shafts 21,22,23 are highly accurate so that it may become parallel to the optical axis L. Therefore, the optical axis alignment of the plurality of movable lens groups (the front movable lens group 30 and the rear movable lens group 40 lens G) guided by the three guide shafts 21, 22 and 23 is increased. Can be done with precision.

  As shown in FIG. 4, the opening 15 is formed so as to open in a substantially rectangular shape, and before the three guide shafts 21, 22, and 23 are inserted, the front movable lens group 30 and the rear movable lens group are movable. The lens group 40 is formed in such a size that it can be inserted into or removed from the housing 10. As described above, by providing the opening 15, the front movable lens group 30 and the rear movable lens group 40 can be easily inserted and assembled into the housing 10 to improve the assembly workability as a whole. be able to.

  As shown in FIG. 4, the opening 16 is formed in a substantially rectangular shape so as to be adjacent to the opening 15 by removing a side wall facing in a direction different from the opening 15 by approximately 90 degrees, and is brought close to the housing 10 from the outside. It is configured to be covered with a part of the drive mechanism 90 attached. Thus, by providing the opening 16 in addition to the opening 15, the front movable lens group 30 and the rear movable lens group 40 can be more easily assembled and removed.

The guide shafts 21 and 22 and the rotation stop guide shaft 23 are each formed to have a circular cross section and extend in the optical axis direction L, and their front end portions are fitted into the corresponding fitting holes 11b, respectively, The end portions are respectively fitted in the corresponding fitting holes 12b, and are fixed to the housing 10 in a state parallel to the optical axis direction L.
The guide shaft 21 guides in the optical axis direction L by slidably connecting a connecting portion 32 of a front movable lens group (second lens group) 30 described later.
The guide shaft 22 guides in the optical axis direction L by slidably connecting a connecting portion 42 of a rear movable lens group (third lens group) 40 described later.
Further, the rotation stop guide shaft 23 slidably connects a connecting portion 33 of a front movable lens group (second lens group) 30 and a connecting portion 43 of a rear movable lens group (third lens group) 40 described later. Thus, it is guided in the optical axis direction L while restricting rotation around the optical axis L together.

As shown in FIGS. 3, 5, and 7, the front movable lens group 30 extends from the lens frame 31 that holds one lens G, and is slidably connected to the guide shaft 21. The first detection sensor 101 extends from the connecting portion 32 having the joint hole, the substantially U-shaped connecting portion 33 extending from the lens frame 31 and slidably connected to the rotation-stop guide shaft 23, and the lens frame 31. A detection piece 34 that can be detected, a substantially U-shaped engagement piece 35 that extends from the lens frame 31 and engages with a first nut 91 c that forms part of the drive mechanism 90, and is provided in the vicinity of the engagement piece 35. The coil spring 50 is provided with a latching portion 36 and the like on which the end of the coil spring 50 is latched.
As shown in FIG. 7, the lens G is a meniscus lens having a positive refractive power convex toward the object side.

  As shown in FIGS. 3, 6, and 7, the rear movable lens group 40 extends from the lens frame 41 that holds the foremost lens G <b> 1, the intermediate lens G <b> 2, and the rear lens G <b> 3, and extends from the lens frame 41 to the guide shaft 22. From the lens frame 41, the connection portion 42 having a fitting hole slidably connected to the lens frame 41, and the substantially U-shaped connection portion 43 extending from the lens frame 41 and slidably connected to the rotation stop guide shaft 23. A detection piece 44 that extends and can be detected by the second detection sensor 102; a substantially U-shaped engagement piece 45 that extends from the lens frame 41 and engages with a second nut 92c that forms part of the drive mechanism 90; A latching portion 46 that extends from the lens frame 41 and that latches the end of the coil spring 50 is provided.

As shown in FIGS. 7 and 8, the front lens G1 is a biconvex lens having a positive refractive power that is convex on both the object side and the image plane side.
As shown in FIGS. 7 and 8, the intermediate lens G2 is a meniscus lens having a negative refractive power that is convex toward the object side.
As shown in FIGS. 7 and 8, the rear lens G3 is a meniscus lens having a negative refractive power that is convex toward the object side.
The foremost lens G1, the intermediate lens G2, and the rear lens G3 as a whole have a stronger refractive power than the other lens groups (the front fixed lens group 60, the front movable lens group 30, and the rear fixed lens group 70). Is set to

As shown in FIGS. 7 and 8, the lens frame 41 has a fitting hole 41a for fitting the intermediate lens G2 and the rear lens G3 from the rear and positioning them on the optical axis L, and the front lens G1 abutting from the front. Both are provided with an annular recess 41b, an aperture plate 41c and the like formed so as to define a gap that can be finely adjusted in a direction perpendicular to the optical axis L.
That is, the lens frame 41 is finely adjusted in a direction perpendicular to the optical axis L after the front lens G1 is fitted into the annular recess 41b after the intermediate lens G2 and the rear lens G3 are fitted and fixed in the fitting hole 41a. Thus, it is formed so as to be fixed using an adhesive or the like after a predetermined adjustment.

As described above, in the rear movable lens group (third lens group) 40, the foremost lens G1 disposed in the foremost position among the plurality of lenses G1, G2, and G3 is provided so as to be aligned with the lens frame 41. Therefore, although the sensitivity of the positional deviation with respect to the optical axis L becomes sensitive by increasing the refracting power, the front lens G1 is aligned and fixed to the lens frame 41 to increase the sensitivity on the optical axis L. It is possible to align with accuracy and obtain desired optical characteristics.
A plurality of lenses included in the rear movable lens group (third lens group) 40 includes a biconvex front lens G1, a meniscus intermediate lens G2 convex toward the object side, and a convex shape toward the object side. Since it is formed by the meniscus-shaped rear lens G3 formed, it is possible to obtain a strong refractive power (power), that is, a predetermined magnification while ensuring desired optical characteristics.

  As shown in FIG. 6, one end of the coil spring 50 is hooked on the hook 36 of the front movable lens group 30, and the other end is hooked on the hook 46 of the rear movable lens group 40. Thus, an urging force is applied so that the front movable lens group 30 and the rear movable lens group 40 are close to each other in the optical axis direction L.

  As shown in FIGS. 3, 5, and 7, the front fixed lens group (first lens group) 60 includes a single lens G, and the optical axis direction L with respect to the front annular fixing portion 11 a of the housing 10. It is formed so as to be inserted and fixed from the front. This lens G is a biconcave lens having negative refractive power that is concave on both the object side and the image plane side.

  As shown in FIGS. 3, 5, and 7, the rear fixed lens group (fourth lens group) 70 includes a single lens G, and has an optical axis with respect to the rear annular fixing portion 12 a of the housing 10. It is formed so as to be inserted and fixed from the rear in the direction L. This lens G is a meniscus lens having a positive refractive power that is concave on the object side and convex on the image surface side.

  As shown in FIGS. 3 and 7, the prism 80 bends subject light (incident light) emitted from the subject in the housing 10 by 90 degrees and arranges the lens optical system (front side) disposed in the housing 10. The fixed lens group 60, the front movable lens group 30, the rear movable lens group 40, and the rear fixed lens group 70) are guided to an image sensor disposed at the rear end of the housing 10. . The prism 80 is inserted so as to be sandwiched between the two extending walls 17 and positioned at a predetermined position by the positioning portion 17c, and the presser cover 120 is coupled to the extending wall 17 of the housing 10 from the outside. As a result, it is fixed in the housing 10.

As shown in FIGS. 3, 5, and 6, the drive mechanism 90 includes a first drive mechanism 91 that drives the front movable lens group 30, a second drive mechanism 92 that drives the rear movable lens group 40, and a first drive. A connection plate 93 that integrally connects the mechanism 91 and the second drive mechanism 92 is provided.
The first drive mechanism 91 is screwed into the first step motor 91a, the first lead screw 91b directly connected to the first step motor 91a, the first lead screw 91b, and the engagement piece 35 of the front movable lens group 30. A first nut 91c engaged from the rear side of the optical axis direction L, a first bearing member 91d fitted to the tip of the first lead screw 91b, a first step motor 91a, and a first bearing member 91d are held. A holding plate 91e and the like are provided.
When the first lead screw 91b is rotated by the activation of the first stepping motor 91a, the first drive mechanism 91 moves the first nut 91c in the optical axis direction L and follows the first nut 91c. Then, the front movable lens group 30 is moved to a desired position in the optical axis direction L.

The second drive mechanism 92 is screwed into the second step motor 92a, the second lead screw 92b directly connected to the second step motor 92a, and the second lead screw 92b, and the engagement piece 45 of the rear movable lens group 40. The second nut 92c engaged from the front side in the optical axis direction L, the second bearing member 92d fitted to the tip of the second lead screw 92b, the second step motor 92a, and the second bearing member 92d are held. A holding plate 92e and the like are provided.
Then, when the second lead screw 92b is rotated by the activation of the second step motor 92a, the second drive mechanism 92 moves the second nut 92c in the optical axis direction L and follows the second nut 92c. Then, the rear movable lens group 40 is moved to a desired position in the optical axis direction L.

  As shown in FIGS. 3, 5, and 6, the connection plate 93 fixes the first holding plate 91 e and the second holding plate 92 e with screws B, and integrates the first drive mechanism 91 and the second drive mechanism 92. It is attached so that the opening part 16 of the housing | casing 10 may be plugged up in the state hold | maintained. In addition, by filling an adhesive 94 such as an epoxy resin between the connecting plate 93 and the first step motor 91a and the second step motor 92a, the gap can be completely sealed, and dust or the like inside the housing 10 can be sealed. Intrusion can be prevented.

Then, the first drive mechanism 91 has a focus drive (focusing operation) and correction drive (the focus is shifted by the zoom drive (the focus position is shifted)) with respect to the front movable lens group (second lens group) 30. The operation for correcting this is performed.
Further, the second drive mechanism 92 performs zoom drive (magnification operation) on the rear movable lens group (third lens group) 40.
That is, in this zoom lens barrel, as shown in FIG. 7, at the rear of the prism 80, the front fixed lens group 60, the front movable lens group 30, the rear movable lens group 40, and the rear fixed lens group 70 are sequentially arranged. The arrangement consists of 6 elements in 4 groups, and the first lens group (front fixed lens group 60) and the fourth lens group (rear fixed lens group 70) are fixed, and the third lens group (rear movable). The lens group 40) is zoom-driven by the second drive mechanism 92, and the second lens group (front movable lens group 30) is focus-driven and corrected by the first drive mechanism 91, so that a predetermined magnification is ensured. The amount of movement of the lens optical system as a whole in the optical axis direction L can be suppressed. As a result, the size of the housing 10 in the optical axis direction L can be shortened, and the zoom lens barrel can be reduced in size. Kill.

The first detection sensor 101 is a transmissive optical sensor including a light projecting element and a light receiving element, and is attached to the concave portion 11e of the housing 10 as shown in FIGS. The first detection sensor 101 detects the initial position of the front movable lens group 30 by blocking the detection light from the light projecting element toward the light receiving element.
The second detection sensor 102 is a transmissive optical sensor including a light projecting element and a light receiving element, and is attached to the recess 12e of the housing 10 as shown in FIGS. The second detection sensor 102 detects the initial position of the rear movable lens group 40 by blocking the detection light from the light projecting element toward the light receiving element.

As shown in FIGS. 2 and 3, the cover 110 is formed using a thin metal plate so as to be flat and have a substantially rectangular outer contour so that the opening 15 can be closed. A circular hole 111 through which the positioning protrusions 11d and 12d are fitted, a latching piece 113 that is latched by the latching claws 13a and 12i, and the like.
The cover 110 is opened after the assembly of the parts (guide shafts 21, 22, 23, the front movable lens group 30, the rear movable lens group 40, the coil spring 50, etc.) housed in the housing 10 is completed. It is configured to be coupled to the housing 10 using screws B so as to cover the portion 15.

The presser cover 120 is formed using a resin material, and as shown in FIGS. 2 and 3, the presser cover 120 is in contact with the four latching pieces 121 and the prism 80 that are latched by the latching claws 17 b of the housing 10. There are provided four contact portions 122 and the like.
As shown in FIGS. 2 and 3, the presser cover 120 inserts the prism 80 so as to be sandwiched between the two extending walls 17, and then fixes the prism 80 while pressing it toward the positioning portion 17c. In addition, the latching piece 121 is latched on the latching claw 17 b and is coupled to the housing 10. Here, since the latching piece 121 is coupled to the latching claw 17b by snap fitting, the presser cover 120 can be easily detached from the housing 10 by bending the latching piece 121 outward.

As shown in FIG. 2, the flexible wiring board 130 has connection terminals for the first step motor 91 a and the second step motor 92 a of the drive mechanism 90, a connection terminal for the first detection sensor 101, and a connection terminal for the second detection sensor 102. It is electrically connected to a control circuit or the like in the mobile phone P, and is formed to bend along the outer walls of the housing 10 and the presser cover 120.
As described above, since the flexible wiring board 130 is arranged along the outer wall in a region deviated from the optical path, it can contribute to the reduction in thickness and size of the zoom lens barrel.

Next, assembly of the zoom lens barrel M will be described.
Prior to assembly, the housing 10, the three guide shafts 21, 22, 23, the front movable lens group 30, the rear movable lens group 40, the coil spring 50, the front fixed lens group 60, the rear fixed lens group 70, the prism 80, a modularized drive mechanism 90, a first detection sensor 101 and a second detection sensor 102, a cover 110, a presser cover 120, a flexible wiring board 130, and the like are prepared.

First, the first detection sensor 101 is fitted into the recess 11 e of the housing 10, and the second detection sensor 102 is fitted into the recess 12 e of the housing 10.
The front movable lens group 30 and the rear movable lens group 40 are inserted into the housing 10 from the opening 15 and held at predetermined positions, and the guide shafts 21 and 22 and the rotation stop guide shaft 23 are arranged in the optical axis direction L. The guide shaft 21 is inserted into the coupling portion 32 of the front movable lens group 30 and the guide shaft 22 is coupled to the rear movable lens group 40. The rotation stop guide shaft 23 is inserted into the connecting portion 43 of the rear movable lens group 40 and inserted into the connecting portion 33 of the front movable lens group 30, and the corresponding fitting hole of the housing 10 is further inserted. 11b, respectively.

As a result, the guide shafts 21 and 22 and the rotation stop guide shaft 23 are in a state in which both ends thereof are fitted and fixed in the fitting holes 11b and 12b of the housing 10, and are high in parallel with the optical axis direction L. Fixed to accuracy.
In addition, the front movable lens group 30 is guided to be movable in the optical axis direction L by the guide shaft 21 while the rotation around the optical axis L is regulated by the rotation stop guide shaft 23, and the rear movable lens group 40 is Thus, the rotation around the optical axis L is regulated by the rotation stop guide shaft 23 and the guide shaft 22 is guided so as to be movable in the optical axis direction L.
Thus, by adopting the dedicated guide shafts 21 and 22 for guiding in the optical axis direction L and the common guide shaft 23 for regulating the rotation around the optical axis L, the structure is simplified and the number of parts is reduced. Thus, the front movable lens group 30 and the rear movable lens group 40 can be guided with high accuracy in the optical axis direction L.

Subsequently, the coil spring 50 is hooked and stretched by the hooking portion 36 of the front movable lens group 30 and the hooking portion 46 of the rear movable lens group 40. The assembly of the coil spring 50 is not limited to this order, and may be assembled later.
Subsequently, the front-side fixed lens group 60 is brought close to the housing 10 from the front in the optical axis direction L, and is inserted into the front-side annular fixing portion 11a and is appropriately fixed using an adhesive or the like.
Subsequently, the rear fixed lens group 70 is brought closer to the housing 10 from the rear in the optical axis direction L, and is inserted into the rear annular fixing portion 12a and fixed with an adhesive or the like as appropriate.
The rear fixed lens group 70 may be assembled first, and then the front fixed lens group 60 may be incorporated.

  Subsequently, the first nut 91c is brought into contact with the engagement piece 35 from the rear side in the optical axis direction L, and the second nut 92c is brought into contact with the engagement piece 45 from the front side in the optical axis direction L to be modularized. The drive mechanism 90 is assembled to the housing 10 so as to be close to the housing 10 from a direction perpendicular to the optical axis direction L and to close the opening 16.

Here, the zoom lens barrel assembled to the drive mechanism 90 is set in a predetermined inspection apparatus, and the front fixed lens group 60, the front movable lens group 30, the rear movable lens group 40, and the rear fixed lens group 70 are set. An optical system characteristic inspection comprising:
Here, if the characteristic inspection is passed, the prism 80 is fitted into the housing 10 and the presser cover 120 is assembled from the outside. In addition, if it is rejected in the characteristic inspection, the process is appropriately shifted to a rework process.
Subsequently, the cover 110 is assembled to the housing 10 with screws B so as to close the opening 15. The cover 110 may be assembled before the prism 80 and the presser cover 120 are assembled.

Finally, the flexible wiring board 130 is wired along the outer wall surfaces of the housing 10 and the presser cover 120 to connect the connection terminals of the first step motor 91a and the second step motor 92a, the first detection sensor 101, and the second detection sensor 101. Each is connected to a connection terminal of the detection sensor 102.
Thereby, the zoom lens barrel is completed.
Thereafter, if necessary, the imaging element is fitted into the recess 12 h located behind the housing 10.

Next, the operation of the zoom lens barrel will be briefly described with reference to FIG.
First, the subject light enters from a direction perpendicular to the prism 80, the optical path is bent by 90 degrees by the prism 80, and the front fixed lens group 60 → front movable lens group 30 → rear movable lens group 40 → The light passes through the rear fixed lens group 70 in order, and is incident on an image pickup device disposed further rearward.
In the resting state, the front lens group 30 is stopped most forward in the optical axis direction L, and the rear movable lens group 40 is stopped most rearward in the optical axis direction L.
Then, the front movable lens group 30 is focus-driven and corrected in the optical axis direction L by the first drive mechanism 91, and the rear movable lens group 40 is zoom-driven in the optical axis direction L by the second drive mechanism 92. From the wide-angle end photographing position shown in FIG. 9 (a), the intermediate photographing position shown in FIG. 9 (b) is followed to the telephoto end photographing position shown in FIG. 9 (c).

  According to the zoom lens barrel M configured as described above, while ensuring the zoom function, the focus function, and the correction function, the structure is simplified, the assembling workability is improved, the assembling accuracy is improved, and the optical axis of the lens is adjusted. A zoom lens barrel suitable for a digital camera (mobile camera) or the like mounted on a mobile phone or the like can be obtained with high accuracy, shortening of the optical axis direction, miniaturization, and the like.

In the above embodiment, the case where the first drive mechanism 91 and the second drive mechanism 92 are integrally modularized as the drive mechanism 90 is shown, but the present invention is not limited to this. A configuration in which the second drive mechanism 92 is separately assembled to the housing 10 may be employed.
In the above embodiment, the first lens group (front fixed lens group 60) is a single lens G, the second lens group (front movable lens group 30) is a single lens G, and the third lens group (rear movable). Although the case where the lens group 40) is the three lenses G1, G2, G3 and the fourth lens group (the rear fixed lens group 70) is a single lens G is shown, the present invention is not limited to this. Other specifications (shape, refraction) can be used as long as the first lens group and the fourth lens group are fixed, the second lens group and the third lens group are movable, and the refractive power of the third lens group can be set large. A lens having a characteristic) may be used.

  As described above, the zoom lens barrel of the present invention ensures the zoom function, the focus function, and the correction function, while simplifying the structure, improving the assembling workability, improving the assembling accuracy, and the optical axis of the lens. It can be applied to a digital camera or the like mounted on a mobile phone or the like that is required to be downsized because it can achieve high accuracy of alignment, shortening in the optical axis direction, downsizing, etc. It is also useful as a zoom lens barrel for other portable information terminals, digital cameras, or installed digital cameras.

It is a perspective view which shows the state which mounted the zoom lens barrel concerning this invention in the mobile telephone. 1 is a perspective view showing an embodiment of a zoom lens barrel according to the present invention. 1 is an exploded perspective view of a zoom lens barrel according to the present invention. It is a perspective view which shows the housing | casing which makes a part of zoom lens barrel. It is sectional drawing which shows the inside of a zoom lens barrel. It is a top view which shows the inside of a zoom lens barrel. It is sectional drawing in the surface containing the optical axis L of a zoom lens barrel. It is sectional drawing which shows the 3rd lens group contained in a zoom lens barrel. 2A and 2B are diagrams for explaining the operation of a movable lens group included in a zoom lens barrel, in which FIG. 1A is a cross-sectional view showing a state at a wide-angle end shooting position, and FIG. 2B is a cross-sectional view showing a state at an intermediate shooting position; (C) is sectional drawing which shows the state in a telephoto end imaging position.

Explanation of symbols

P Mobile phone P1 Cover M Lens barrel L Optical axis direction 10 Housing 11 Front wall 11a Front annular fixing portion 11b Fitting hole 11c Screw hole 11d Positioning projections 11e, 11f Recess 12 Rear wall 12a Rear annular fixing portion 12b Fitting Joint hole 12c Screw hole 12d Positioning protrusion 12e, 12f Recessed part 12g Flange part 12h Recessed part 12i, 13a Stopping claw 13, 14 Side wall 14a Positioning protrusion 14b Circular hole 15, 16 Opening part 17 Extension wall 17a Screw hole 17b Stopping claw 17c Positioning portions 21, 22 Guide shaft 23 Anti-rotation guide shaft 30 Front movable lens group (second lens group)
31 Lens frame G Lens 32, 33 Connecting part 34 Detection piece 35 Engagement piece 36 Locking part 40 Rear movable lens group (third lens group)
41 Lens frame G1 Front lens G2 Intermediate lens G3 Rear lenses 42, 43 Connecting portion 44 Detection piece 45 Engagement piece 46 Latching portion 50 Coil spring 60 Front side fixed lens group (first lens group)
G lens 70 Rear fixed lens group (fourth lens group)
G lens 80 prism (bending element)
90 drive mechanism 91 first drive mechanism 91a first step motor 91b first lead screw 91c first nut 91d first bearing member 91e first holding plate 92 second drive mechanism 92a second step motor 92b second lead screw 92c second Nut 92d Second bearing member 92e Second holding plate 93 Connection plate 94 Adhesive 101 First detection sensor 102 Second detection sensor 110 Cover 111, 112 Circular hole 113 Holding piece 120 Pressing cover 121 Holding piece 122 Contact portion 130 Flexible wiring board

Claims (5)

A housing extending in the direction of the optical axis;
A lens optical system including a first lens group, a second lens group, a third lens group, and a fourth lens group, which are sequentially arranged in the optical axis direction in the housing;
A drive mechanism for driving a lens group included in the lens optical system,
The first lens group and the fourth lens group are fixed to the housing, and the second lens group and the third lens group are zoom lens barrels that are movably supported in the optical axis direction,
The drive mechanism includes a first drive mechanism that performs focus drive and correction drive on the second lens group, and a second drive mechanism that performs zoom drive on the third lens group.
A zoom lens barrel characterized by that. The third lens group is set to have a refractive power larger than that of the first lens group, the second lens group, and the fourth lens group.
The zoom lens barrel according to claim 1. The third lens group includes a lens frame and a plurality of lenses held by the lens frame,
The lens arranged in the forefront among the plurality of lenses is provided so as to be aligned with the lens frame.
The zoom lens barrel according to claim 2. The third lens group includes a biconvex front lens, a meniscus intermediate lens convex on the object side, and a meniscus rear lens convex on the object side.
The zoom lens barrel according to claim 3. In the case, a bending element is arranged in front of the first lens group to bend incident light and guide it to the lens optical system.
The zoom lens barrel according to claim 1, wherein the zoom lens barrel is provided.

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