JP2003295030A - Lens unit and electronic camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens unit and an electronic camera which are free from backlash and the occurrence of out-of-focus, in which the allowance of axis-to- axis accuracy can be made greater and which can be formed compactly. <P>SOLUTION: The lens unit is mainly characterized in that it is equipped with a lens frame 22 holding a lens 21 movably in an optical axis direction; a lead screw 25 rotated by a driving source 24; 1st and 2nd nut members 26 and 27 screwed in the screw 25 at a specified interval and simultaneously moved in an axial direction with the rotation of the screw 25; a 1st energizing member 28 for energizing the 1st and the 2nd nut members in a direction where they approach to each other or they separate from each other; a driving force transmission part 26b provided at one part of the 1st nut member 26, transmitting driving force to the lens frame 22 to move the lens frame 22 in the optical axis direction; and a 2nd energizing member 30 for energizing the transmission part 26b to abut it on the lens frame 22 by pressure. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens unit in which a lens group is moved in an optical axis direction by a lead screw which is rotationally driven by a driving source, and an electronic camera including the lens unit.

[0002]

2. Description of the Related Art A lens unit in which a lens group is moved in an optical axis direction by a lead screw which is rotationally driven by a drive source is disclosed in, for example, Japanese Patent Laid-Open No. 11-8420.
No. 9 publication and the like.

[0003]

In the conventional lens unit disclosed in the above publication, the backlash between the lead screw and the rack portion attached to the lens holding member meshing with the lead screw is prevented. No special means for reducing or reducing the parallelism between the axes, that is, the accuracy for the axes is provided. For this reason,
Depending on the shooting posture of the shooting device, there is a possibility that defocus or the like due to the backlash may occur. Further, in manufacturing, high working precision and high precision assembly work are required.

However, if a backlash reducing means, an inter-axis accuracy reducing means, etc. are provided by using a known technique in order to solve the above-mentioned problems, the lens unit will be upsized. For this reason, there is a problem that it is difficult to take the above-described means for a lens unit mounted on an electronic camera (particularly a compact camera) whose downsizing is an important selling point.

The present invention has been made under the above circumstances, and an object thereof is to provide a lens unit and an electronic camera having the following advantages.

(A) There is almost no backlash, and there is no risk of defocusing or the like due to the shooting posture.

(B) The inter-axis accuracy can be relaxed, and high machining accuracy and high-precision assembly work are not required.

(C) It is possible to maintain a compact form without causing an increase in size.

[0009]

In order to solve the problems and achieve the objects, the lens unit and the electronic camera of the present invention have the following characteristic configurations. In addition, characteristic configurations other than the following will be clarified in the embodiments.

(1) In the lens unit of the present invention, the lens frame that holds the lens so as to be movable in the optical axis direction of the lens, the lead screw that is rotationally driven by the drive source, and the lead screw with a predetermined interval. First and second nut members that are placed and screwed together and that are moved simultaneously with the rotation of the lead screw in the axial direction of the lead screw, the first nut member, and the second nut member.
A first biasing member that is provided between the nut member and the first nut member and that biases both nuts toward and away from each other, and a part of the first nut member that is driven by the lead screw. A driving force transmitting section that transmits force to the lens frame to move the lens frame in the optical axis direction, and a second attaching unit that applies an urging force to press the driving force transmitting section against the lens frame. And a biasing member.

In the above lens unit, the first nut members are opposed to each other at a constant interval.
The first biasing member interposed between the nut member and the second nut member provides a biasing force in the axial direction. Further, the driving force transmitting portion of the first nut member is given an urging force by the second urging member such that it is pressed against the lens frame. Therefore, the first nut member is efficiently urged by the relatively small first urging member and the second urging member, and the backlash is stably and accurately reduced.

(2) The electronic camera of the present invention is the same as the above (1).
It is characterized in that the lens unit described in is mounted.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 (a)
(B) is a figure which shows schematic structure of the electronic camera (compact type camera) which concerns on 1st Embodiment of this invention, (a) is a perspective view which shows the external appearance of a camera, (b) is arrangement | positioning of components in a camera. It is a perspective view showing a state. 2A and 2B are views showing the configuration of the lens unit according to the embodiment,
(A) is a perspective view showing a lens unit together with an image sensor,
(B) is an exploded perspective view showing a configuration of a main part of the unit.

As shown in FIGS. 1A and 1B, the electronic camera 10 is provided with a photographing range window 11 and a strobe light irradiation window 12 on its front surface, and a release button 13 on its upper surface. ing. Inside the electronic camera 10, there is arranged a reflective optical member 14 that reflects the light flux from the subject that has entered through the photographing range window 11 to bend the photographing optical axis OA at a substantially right angle and guide it to the lower side of the camera. A bent optical axis OA is provided below the reflective optical member 14.
A lens unit 15 and an image sensor 16 are arranged along the line. The image pickup device 16 is composed of, for example, a CCD and is supported on a substrate 17. On the side of the lens unit 15, a circuit board 18 on which electronic circuit components and the like are mounted, a battery 19 and the like are arranged.

As shown in FIG. 2A, the lens unit 15 includes a correction lens group 20 and a variable power lens group 4.
0 and 0 are driven by independent drive systems.

The correction system lens group 20 comprises a lens group 21 and a lens frame 22 which holds the lens group 21 movably in the optical axis OA direction. In this lens frame 22, a through hole provided in the main guide portion 22a is fitted with a first guide shaft 23A arranged in parallel with the optical axis OA, and a cut portion provided in the sub guide portion 22b is provided as a second cut portion. It is engaged with the guide shaft 23B and can slide along both guide shafts. A lead screw 25 is arranged substantially parallel to the moving direction of the lens frame 22. The lead screw 25 is rotationally driven by a stepping motor 24 which is a correction system lens drive source, and can transmit a driving force to the lens frame 22 via a nut member described later.

The variable power lens group 40 comprises a lens group 41 and a lens frame 42 which holds the lens group 41 so as to be movable in the optical axis OA direction. The lens frame 42 has a through hole provided in the main guide portion 42a fitted with the first guide shaft 23A arranged parallel to the optical axis OA, and provided in the sub guide portion 42b (not shown). The notch is engaged with the second guide shaft 23B and can slide along both guide shafts. A lead screw 45 is arranged substantially parallel to the moving direction of the lens frame 42. The lead screw 45 is rotationally driven by a stepping motor 44 which is a variable-magnification lens drive source, and can transmit a driving force to the lens frame 42 via a nut member 46.

As shown in FIG. 2 (b), the lead screw 25 has first and second nut members 26 and 27.
However, they are screwed at a predetermined interval. First of these
The second nut members 26 and 27 are restricted from rotating themselves as described later. Therefore, as the lead screw 25 rotates, the lead screw 25 simultaneously moves in the axial direction.

Between the first nut member 26 and the second nut member 27, a first urging member 28 consisting of a coil spring for urging the nuts 26, 27 in a direction in which they are separated from each other is mounted. Has been done.

The first nut member 26 has a ring portion 2 in which a female screw portion M is screwed into the lead screw 25.
6a, and a driving force transmitting portion 26b provided at one end of the ring portion 26a so as to project.

The driving force transmitting portion 26b is a portion that transmits the driving force from the lead screw 25 to the lens frame 22 and moves the lens frame 22 in the optical axis OA direction.
An elongated hole engaging hole N that is loosely fitted into a shaft member 29 described later is provided at the tip portion of the driving force transmitting portion 26b. The long hole engagement hole N is engaged with the lens frame 22 in such a manner that the driving force transmitting portion 26b is allowed to be relatively displaced in a direction substantially orthogonal to the moving direction of the lens frame 22. Work as a department.

The lens frame 22 has a pair of support members 22c and 22d facing each other along the moving direction. Each of the support members 22c and 22d is provided with a support hole, and the shaft member 29 is supported with the both ends 29a and 29b penetrating the support hole. The shaft member 29 has an elongated hole engaging hole N of the driving force transmitting portion 26b.
Is locked in a loosely fitted state, and guides the second biasing member 30 formed of a coil spring fitted in a compressed state. Thus, the driving force transmitting portion 26b is pressed against the inner surface of the one supporting member 22c by the second biasing member 30.

The second nut member 27 has a female thread portion M on the inner peripheral surface and a cylindrical portion 2 having an outer peripheral surface having a cylindrical surface on which the first biasing member 28 composed of the coil spring can be wound.
7a, a flange portion 27b as a stopper provided near one end of the tubular portion 27a, and a corner head portion 27c slightly protruding from the flange portion 27b along the axial direction.

A rotation restricting member 31 is provided between the head portion 27c of the second nut member 27 and the other end portion 29b of the shaft member 29.
Are connected by. The rotation restricting member 31 has a square head portion 27 of the second nut member 27 at one end portion of the oval plate.
It has a square hole V that fits into c, and an elongated hole engaging hole W that engages with the other end portion 29b of the shaft member 29 at the other end portion of the oval plate. A locking groove is provided in the other end 29b of the shaft member 29 with which the elongated hole W is engaged, and an E-ring 32 for retaining is fitted into the locking groove. Thus, the second nut member 27 is restricted from rotating by the rotation restricting member 31.

(Second Embodiment) FIG. 3 is an exploded perspective view showing a structure of a main part of a lens unit according to a second embodiment of the present invention. The present embodiment differs from the first embodiment in that instead of providing the shaft member 29, a guide shaft 23A for moving the lens frame 22 in the optical axis OA direction (a guide shaft 23B if possible) may be used. ) To the shaft member 2
The point that a dual function for exhibiting the same function as 9 is provided, and the means for restricting the self-rotation of the second nut member 27,
The point is that a rotation restricting member 51 that connects the first nut member 26 and the second nut member 27 is provided.

The above-mentioned combined means is provided with support members 22c 'and 22d' on the main guide portion 22a, and the support members 22c 'and 22d' are provided.
The oblong hole engaging hole N of the first nut member 26 is engaged with the guide shaft 23A penetrating the supporting holes of c ', 22d', and the second urging member 30 is fitted into the guide shaft 23A so that the above-mentioned first The nut member 26 is urged.

The drive restricting member 51 has a ring portion 51c fitted to the head portion 27c of the second nut member 27 and an outer circumference 180 of the ring portion 26a of the first nut member 26.
° A pair of engagement grooves 26d and 26e provided at different positions,
The second nut member 27 is composed of a pair of connecting pieces 51d and 51e for connecting between the outer peripheral surface of the flange portion 27b and the engaging grooves 27d and 27e provided in the same manner as above.

(Third Embodiment) FIG. 4 is an exploded perspective view showing a structure of a main part of a lens unit according to a third embodiment of the present invention. The present embodiment is different from the second embodiment in that the threaded portion R of the first nut member 26 and the threaded portion S of the second nut member 27 each have one end of the lead screw 25. The first nut member 26 and the second nut member 27 are provided as a means for restricting the self-rotation of the second nut member 27 by having a structure that opens in the direction orthogonal to the axis. The point is that the rotation restricting member 61 is provided so as to connect the protruding members to each other. The rotation restricting member 61 is the first nut member 26.
Connecting rod 61 projecting from one side surface of the driving force transmitting portion 26b
a and a connecting piece 61c in which the flange portion of the second nut member 27 is deformed and protruded in a direction perpendicular to the axial direction, and a notch portion 61b that engages with the tip end portion of the connecting rod 61a is provided at the protruding end thereof. Consists of.

(Modification) The lens unit shown in the embodiment includes the following modifications.

As the first biasing member 28, first and second
Using a spring that urges the nut members 26 and 27 of the above in a direction of approaching each other.

The driving force transmitting portion 2 of the first nut member 26
A notch having a structure in which the long hole engaging hole N provided in 6b is opened in a direction orthogonal to the shaft member similarly to the screwing portions R and S.

First nut member 26 having a threaded portion R
The long hole engaging hole N provided in the driving force transmitting portion 26b is a circular hole fitted to the shaft member.

(Characteristics of the Embodiment) [1] In the lens unit 15 shown in the embodiment, the lens frame 22 that holds the lens 21 movably in the optical axis OA direction of the lens 21, and the drive source ( Step motor) 2
A lead screw 25 which is rotationally driven by 4 and is screwed into the lead screw 25 at a predetermined interval,
First and second nut members 26, 27 provided so as to move simultaneously in the axial direction of the lead screw 25 with the rotation of the lead screw 25, the first nut member 26, and the second nut member. It is provided between 27 and
A first urging member 28 for urging the two nuts 26, 27 toward or away from each other, and the first nut member 2
6 is provided in a part of the lens frame 6, and the driving force from the lead screw 25 is transmitted to the lens frame 22.
Driving force transmitting portion 26b for moving the optical disc 2 in the optical axis OA direction
And a second biasing member 30 that applies a biasing force so that the driving force transmitting portion 26b is pressed against the lens frame 22.
It is characterized by having and.

In the lens unit 15, the first
The nut member 26 of the axial direction is axially moved by the first urging member 28 interposed between the first nut member 26 and the second nut member 27 which are opposed to each other with a constant interval. Is given the urging power of. The driving force transmitting portion 26b of the first nut member 26 is biased by the second biasing member 30 so as to be pressed against the lens frame 22.
Therefore, the first nut member 26 is efficiently urged by the relatively small-sized first urging member 28 and the second urging member 30, and the backlash is stably and accurately reduced.

[2] The lens unit 15 shown in the embodiment is the lens unit described in [1] above,
The driving force transmission portion 26b is provided with respect to the lens frame 22.
It is characterized in that it has an engaging portion N that engages in a manner that allows relative displacement in a direction substantially orthogonal to the moving direction of the lens frame 22.

In the above-mentioned lens unit 15, even if the parallelism between the moving direction of the lens frame 22 and the axial direction of the lead screw 25 is slightly poor, the dimensional error is caused by the lens frame 22.
It is absorbed by the relative displacement of the engaging portion N with respect to. Therefore, the accuracy between axes is relaxed. Thus,
In the lens unit 15, in addition to the effect of reducing backlash in the driving force transmission system that transmits the driving force from the driving source 24 to the lens frame 22, the axial direction of the moving direction of the lens frame 22 and the axial direction of the lead screw 25. The effect of relaxing the inter-axis accuracy, which reduces the inter-accuracy, is realized simultaneously with the compact mechanism. Therefore, the lens unit 15 can be downsized.

[3] The lens unit 15 shown in the embodiment is the lens unit according to the above [1] or [2], and the lens frame 22 has a pair of supporting members facing each other along the moving direction. The members 22c and 22d and the supporting member 2
2c, 22d, and a shaft member 29 that guides the second biasing member 30. The shaft member 29 locks the engaging portion N of the driving force transmission portion 26b and locks the engaging portion N. It is characterized in that the engaging portion N of the driving force transmitting portion 26b is provided so as to be urged by the second urging member 30.

In the lens unit 15, the shaft member 29 supported by the pair of support members 22c and 22d is
Since the member that restricts the rotation of the first nut member 26 also serves as the member that guides the second biasing member 30, the size of the lens unit 15 can be reduced.

[4] The lens unit 15 shown in the embodiment is the lens unit described in [1], [2] or [3], and the second nut member 27 is the nut member. It is characterized in that its own rotation is restricted by a rotation restriction member 31 provided so as to connect between 27 and the shaft member 29.

[5] The lens unit 15 shown in the embodiment is the lens unit described in [1], [2] or [3], and the second nut member 27 is the nut member. The rotation restricting members 51 and 61 provided so as to connect 27 and the first nut member 26 are restricted from rotating themselves.

[6] The lens unit 15 shown in the embodiment is the lens unit according to any one of [3] to [5], and the shaft member includes the lens frame 22. Guide shaft 23 for moving in the optical axis OA direction
It is characterized by A and 23B.

The above lens unit does not require any special shaft member, so that the structure is simple and can be manufactured in a small size.

[7] The lens unit 15 shown in the embodiment is the lens unit according to any one of [1] to [6], and the first nut member 26 is provided.
At least one of the second nut member 27 and the second nut member 27 has a structure in which the threaded portions R and S are opened in a direction orthogonal to the axis of the lead screw 25.

In the lens unit 15, the nut member can be screwed onto the middle portion of the lead screw 25 from the direction orthogonal to the axis of the lead screw 25. Therefore, the assemblability is remarkably improved. Further, the open structure of the screwed portion allows relative displacement in the direction orthogonal to the axis of the lead screw 25, so that
The driving force transmitting portion 26b of the nut member 26 need not be provided with any special means for allowing the relative displacement.

[8] The lens unit 15 shown in the embodiment is the lens unit described in any one of the above [1] to [7], and the reflecting optical member 14 that bends the light beam incident from the subject. It is characterized by having.

[9] Electronic camera 10 shown in the embodiment
Is equipped with the lens unit 15 according to any one of [1] to [8].

[0047]

According to the present invention, it is possible to provide a lens unit and an electronic camera having the following operational effects.

(A) The first nut member is given a predetermined urging force to a required portion by the first urging member and the second urging member. Therefore, there is almost no backlash, and there is no risk of defocusing or the like due to the shooting posture.

(B) Even if there is some error in the parallelism between the moving direction of the lens frame and the axial direction of the lead screw,
The error is absorbed by the relative displacement of the engaging portion in the driving force transmitting portion with respect to the lens frame. As a result, the inter-axis accuracy can be relaxed, and high machining accuracy and high-precision assembly work are not required.

(C) The first biasing member is always interposed between the first and second nut members facing each other with a constant interval. For this reason, the first urging member is small in size and can sufficiently exhibit the required function. The shaft member also serves as a rotation restricting member for the first nut member and a guide member for the second biasing member. Further, when the guide member for guiding the lens frame is used as the shaft member, the dedicated shaft member is not necessary. Therefore, it is not necessary to increase the size, and the compact aspect can be maintained.

[Brief description of drawings]

1A and 1B are diagrams showing a schematic configuration of an electronic camera according to a first embodiment of the present invention, in which FIG. 1A is a perspective view showing an appearance of a camera, and FIG. 1B is a perspective view showing a state of arranging components in the camera. .

2A and 2B are views showing the configuration of the lens unit according to the first embodiment of the present invention, FIG. 2A is a perspective view showing the lens unit together with an image sensor, and FIG. 2B is an exploded view showing the configuration of the main part of the unit. It is a perspective view.

FIG. 3 is an exploded perspective view showing a configuration of a main part of a lens unit according to a second embodiment of the present invention.

FIG. 4 is an exploded perspective view showing a configuration of a main part of a lens unit according to a third embodiment of the present invention.

[Explanation of symbols]

10 ... Electronic camera 11 ... Shooting range window 12 ... Strobe light irradiation window 13 ... Release button OA ... Optical axis 14 ... Reflective optical member 15 ... Lens unit 16 ... Image sensor 17 ... Board 18 ... Circuit board 19 ... Battery 20 ... Correction lens group 40 ... Variable magnification lens group 21 ... Lens group 22 ... Lens frame 23A ... First guide shaft 23B ... second guide shaft 25 ... Lead screw 24 ... Stepping motor (drive source) 26, 27 ... First and second nut members 26b ... Driving force transmitting portion 28 ... First urging member 29 ... Shaft member 30 ... Second biasing member 22c, 22d and 22c ', 22d' ... Support member 31, 51, 61 ... Rotation restriction member 32 ... E-ring N, W ... Long hole engaging hole R, S ... Threaded part (open structure)

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Claims (9)

[Claims] 1. A lens frame for holding a lens movably in the optical axis direction of the lens, a lead screw rotatably driven by a driving source, and a lead screw screwed at a predetermined interval to the lead screw. The first and second units provided so as to move simultaneously in the axial direction of the lead screw as the screw rotates.
Nut member, a first biasing member that is provided between the first nut member and the second nut member, and biases both nuts toward or away from each other; A driving force transmitting portion that is provided in a part of the member and that transmits the driving force from the lead screw to the lens frame to move the lens frame in the optical axis direction, and the driving force transmitting portion is the lens frame. And a second urging member that applies an urging force so as to be pressed against the lens unit. 2. The driving force transmitting portion has an engaging portion that engages with the lens frame in a manner that allows relative displacement in a direction substantially orthogonal to the moving direction of the lens frame. The lens unit according to claim 1, wherein the lens unit is a lens unit. 3. The lens frame includes a pair of support members facing each other along a moving direction, and the second frame supported by the support members.
And a shaft member for guiding the urging member, and the shaft member locks the engagement portion of the driving force transmission portion, and the locking portion of the driving force transmission portion is locked by the second portion. The lens unit according to claim 1 or 2, wherein the lens unit is provided so as to be biased by a biasing member. 4. The rotation of the second nut member is restricted by a rotation restricting member provided so as to connect the nut member and the shaft member. Item 1. The lens unit according to Item 1, 2 or 3. 5. The rotation of the second nut member is restricted by a rotation restricting member provided so as to connect the nut member and the first nut member. The lens unit according to 1 or 2 or 3. 6. The lens unit according to claim 3, wherein the shaft member is a guide shaft for moving the lens frame in the optical axis direction. 7. A structure in which at least one of the first nut member and the second nut member has a threaded portion opened in a direction orthogonal to the axis of the lead screw. The lens unit according to any one of claims 1 to 6. 8. The lens unit according to claim 1, further comprising a reflective optical member that bends a light beam incident from a subject. 9. An electronic camera equipped with the lens unit according to any one of claims 1 to 8.