JP2000035528A - Lens driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens driving device which can be accurately moved to a specified position by a motor whatever position a movable lens is at by using one photoelectric detector. SOLUTION: The rollers 13, 14 and 15 attached to the shafts 16, 17 and 18 of lens frames 10, 11 and 12 are engaged with the long holes 9c, 9d and 9e of a cylindrical fixing member 9 and the cam groove of a cylindrical rotating member 24 and when the member 24 is rotated around an optical axis, the frames 10, 11 and 12 are moved in the optical axis direction. An extending part 24b facing the inside of the optical path of a photointerruptor 28 is provided on the outside periphery of the member 24. The part 24b is formed over the specified rotational angle of the member 24 and the output level of the photointerruptor 26 can be consecutively changed by the rotation of the member 24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera, a telescope, a microscope, etc., which makes it possible to move a movable lens to a predetermined position in the direction of an optical axis by a motor for zooming and focusing. The present invention relates to a lens driving device applied to various optical devices.

[0002]

2. Description of the Related Art When a movable lens is moved in a direction of an optical axis by a motor, a cylindrical rotating member rotated by the motor about the optical axis and a cylindrical rotating member having a lens mounted inside rotate the rotating member. It is common practice to provide a lens frame that is moved in the direction of the optical axis at the time of the movement, to detect the rotational position of the cylindrical rotating member by a detector, and to stop the movable lens at a predetermined moving position.

A specific structure for interlocking the cylindrical rotating member and the lens frame is disclosed in Japanese Patent Application Laid-Open No. 5-530.
As described in Japanese Patent Publication No. 39, there is provided a cylindrical fixing member having a plurality of linear long grooves parallel to the optical axis, and the cylindrical rotating member has a plurality of cam grooves. And is disposed rotatably outside the cylindrical fixing member, and the lens frame is disposed inside the cylindrical fixing member,
There is one in which a plurality of shaft portions projecting in the radial direction are fitted into both the long groove and the cam groove.

Another specific structure is described in Japanese Patent Application Laid-Open No. 9-90452. According to this configuration, the annular end surface of the cylindrical rotary member is formed as a cam surface, and the lens frame is provided with a contact pin parallel to the optical axis. Thus, the lens frame is urged by a spring so that the tip of the contact pin always contacts the cam surface. Further, in addition to these two examples, there are also those belonging to the modified examples, and those in which a screw mechanism or a gear mechanism is interposed in interlocking the cylindrical rotating member and the lens frame.

On the other hand, when detecting the rotational position of a cylindrical rotating member, a transmission type photoelectric detector called a photo-interrupter is almost always used at present. Usually, as described in the above two publications, an on / off signal is output alternately by a combination of the photointerrupter and a rotary slit plate having a plurality of holes. It is configured as a pulse control type encoder that performs the rotation position of the cylindrical rotary member by counting the number of pulses from the initial position,
That is, the movement position of the lens frame is detected and stopped when a predetermined number of pulses is reached.

[0006]

Incidentally, the above-mentioned cylindrical rotating member cannot always start rotating from a predetermined position in the optical apparatus. For example, when used in an automatic focusing device of a photographic camera, when shooting is completed, the cylindrical rotating member returns to the initial position, and rotates from the initial position to a predetermined position in the next shooting. However, when the battery runs out, the tubular rotating member may stop at a position other than the predetermined initial position. Also, due to tolerances between components, the initial position of the cylindrical rotary member may not be constant, and may be shifted depending on how the camera is held. Therefore, the cylindrical rotary member is rotated from a position other than such a normal initial position by pulse control of the encoder,
If positioning is performed, it will not be possible to stop at a position where accurate focus adjustment can be performed.

Therefore, in order to prevent such a situation, prior to photographing, the cylindrical rotary member is once returned to the initial position, and after confirming the return to the initial position, the above-described operation is performed. It is necessary to rotate the cylindrical rotating member to a predetermined adjustment position while counting the number of pulses by the encoder. Therefore, conventionally, when the cylindrical rotary member is once returned to the initial position, another detector for confirming the return is provided.
However, providing two detectors is not only inconvenient for downsizing optical equipment, but also extremely disadvantageous in cost.

The present invention has been made to solve such a problem, and an object of the present invention is to use one photoelectric detector without the need for the two detectors as described above. It is an object of the present invention to provide a lens driving device capable of effectively performing a predetermined position control of a movable lens.

[0009]

In order to achieve the above-mentioned object, a lens driving device according to the present invention comprises a cylindrical rotating member rotated about an optical axis by a motor, and a lens mounted inside. A lens frame that is moved in the optical axis direction when the cylindrical rotating member rotates, and a photoelectric detector that outputs a signal of a level corresponding to the amount of received light is provided, and an outer peripheral portion of the cylindrical rotating member is provided. An overhanging portion that faces the detection optical path of the photoelectric detector and is configured to continuously change the amount of light received by the photoelectric detector by rotation of the cylindrical rotating member; The moving position of the lens frame is detected according to the level of the output signal of the detector. Further, in the lens driving device of the present invention, a cylindrical fixing member having at least one long groove is further provided, and the cylindrical rotating member is provided with at least one cam groove, The lens frame is provided with at least one shaft protruding in the radial direction, and it is advantageous in terms of cost if the shaft is fitted in both the long groove and the cam groove. . In this case, if the lens frame is arranged inside the cylindrical fixing member and the cylindrical rotating member is arranged outside the cylindrical fixing member, it is advantageous for miniaturization. Further, in the lens driving device of the present invention, the projecting portion of the cylindrical rotating member is configured such that the projecting amount from the center of the optical axis gradually changes over a predetermined rotation angle range of the cylindrical rotating member. If the light-shielding wall is formed in such a manner, it becomes more preferable in manufacturing.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to two examples. In each of these embodiments, the present invention is applied to a photographing optical system for a camera having a zooming function. 1 to 4 are for explaining the first embodiment, FIG. 1 is a sectional view showing the structure of the first embodiment, and FIG. 2 is a photointerrupter shown in FIG. It is a figure showing a change of the output signal from 26. Also,
FIG. 3 is a view of the cylindrical rotary member 24 shown in FIG. 1 as viewed from the left side of FIG. 1, and FIG. 4 is a view of a cam groove formed in the peripheral surface of the cylindrical rotary member 24 viewed from the outer peripheral surface side. FIG. FIGS. 5 and 6 are views for explaining the second embodiment. FIG. 5 is a sectional view showing the structure of the second embodiment. FIG. FIG. 6B is a diagram illustrating a change in the output signal, and FIG. 6B is a diagram illustrating a change in the output signal from the photointerrupter.
In the two embodiments, substantially the same members and the same parts are denoted by the same reference numerals.

First Embodiment First, the structure of the first embodiment will be described with reference to FIGS. 1, 3 and 4. In FIG. 1, the left side is the object side and the right side is the image. Face side. A support plate 2 is attached to the subject side of the substrate 1, and a drive motor 3 is attached to the image forming surface side by appropriate means. The output shaft 3a of the drive motor 3
And the support plate 2, on which the gear 4 is mounted by press-fitting. Gears 5 and 6 are rotatably supported between the substrate 1 and the support plate 2.
A gear 8 is rotatably mounted on the shaft 7 fixed to the shaft 7. Therefore, the rotation of the gear 4 is reduced and transmitted to the gear 8.

A cylindrical fixing member 9 accommodating all photographing optical systems is attached to the substrate 1 by a method not shown. A flange 9a is formed on the subject side of the cylindrical fixing member 9, and a hole 9b is provided therein. Actually, three holes 9b are provided at substantially equal angular intervals about the optical axis, and the cylindrical fixing member 9 is attached to a camera body (not shown) by passing screws therethrough. It has become. The cylindrical fixing member 9 is formed with three linear long grooves 9c, 9d, 9e parallel to the optical axis. Actually, three sets of the long grooves 9c, 9d, 9e are provided at substantially equal angular intervals around the optical axis, but FIG. 1 shows only one of them.
Note that these long grooves 9c, 9d, 9e do not necessarily have to be formed parallel to the optical axis.

Inside the cylindrical fixing member 9, three lens frames 10, 11, 12 movable along the optical axis are provided.
Are disposed, the lens group 10 has a first group of lenses, the lens frame 11 has a second group of lenses, and the lens frame 12 has a
Are provided with lenses of the fourth group, respectively. The lens of the second group is a lens for zooming, and the lens of the fourth group is a lens for focus adjustment. Also, lens frame 1
Rollers 13, 14 and 14 are provided on the outer peripheral surfaces of 0, 11 and 12, respectively.
Shafts 16, 17, and 18 to which 15 is attached are erected, and the rollers 13, 14, and 15 are fitted in the long grooves 9 c, 9 d, and 9 e formed in the cylindrical fixing member 9. . The shafts 16, 17, and 18 are also provided upright at substantially equal angular intervals around the optical axis, and the rollers attached thereto are connected to the long grooves 9c, 9c.
It is fitted in each long groove having the same shape as d and 9e.

Further, inside the cylindrical fixing member 9, there is formed a projecting portion 9f having an annular shape with the optical axis as a center.
0 is attached. Between the shutter base plate 20 and the auxiliary base plate 21, two shutter blades 22 which are also used as aperture blades are arranged. Also, the shutter base plate 20
, A motor 23 for driving the shutter blades 22 is attached, and a lens of the third group is attached.

A cylindrical rotating member 24 is rotatably fitted to the outer periphery of the cylindrical fixing member 9. As shown in FIG. 3, the cylindrical rotating member 24 is formed with a tooth portion 24a and an overhang portion 24b over a predetermined angle around the optical axis. Are engaged. Further, the overhang portion 24b is formed such that the radial distance gradually changes in the rotation direction. As shown in FIG. 1, a photo-interrupter 26 is
Is attached, and the overhang portion 24b is provided in the optical path.
Are arranged. Therefore, the overhang portion 24b
Functions as a light shielding wall that can change the amount of light received by the photo interrupter 26 in accordance with the rotational position of the cylindrical rotating member 24.

As shown in the development of FIG. 4, three cam grooves 24c, 24d and 24e are formed in the cylindrical rotary member 24.
Are formed. Actually, these three cam grooves 24c, 24c are located at substantially equal angular positions around the optical axis.
Although four sets of 4d and 24e are formed, only one of them is shown in FIG. And
A roller 1 is provided in the cam groove 24c formed on the subject side.
3, the roller 14 is fitted in the cam groove 24d, and the roller 15 is fitted in the cam groove 24e. Therefore, the cylindrical rotating member 24 is rotated by a predetermined angle about the optical axis, and thereby the lens frames 10, 11, 12 are moved.
It is designed to move linearly along the optical axis.

The first group of lenses mounted on the lens frame 10 is moved for aberration correction in the present embodiment, but may be moved to the cylindrical fixing member 9 in some cases. It can be fixed. Also,
In the case of the present embodiment, three cam grooves 24c, 24d, 2
Although three sets of 4e are formed, one set may be theoretically used. In such a case, the slots 9c, 9d, and 9e described above are also
The shafts 16, 17, 18 to which the 14, 14 are attached may be one set. However, although the cost is high, a plurality of sets are desirable in terms of function.

Next, the operation of this embodiment will be described. In this embodiment, as can be seen from the shape of the cam groove 24d shown in FIG. 4, a variable magnification system generally called a step zoom is adopted. Then, the rollers 13 attached to the shafts 16, 17, 18 of the lens frames 10, 11, 12
In the initial position of the cylindrical rotating member 24, reference numerals 14 and 15 are located below the cam grooves 24c, 24d and 24e in FIG. Accordingly, at this time, the lens of the second group for zooming is located on the leftmost side in FIG.

Then, this step is changed to the step of zooming 1 (Z1).
Then, in the case of the present embodiment, the stage of zooming 5 (Z5)
Up to five levels are controlled. The focus adjustment is performed at each magnification step (Z1 to Z5) of the lens frame 11. Therefore, the order of each of the magnification stages (Z1 to Z5) and each of the focus adjustment stages (F1 to F5) is as follows from the initial position of the cylindrical rotary member 24 to Z1, F1, Z2, F2, Z3.
The order is F3, Z4, F4, Z5, and F5. FIG. 2 shows the relationship between each of these steps and the signal output from the photo interrupter 26. Further, the lens frame 11 does not move in each focus adjustment stage (F1 to F5) due to the shape of the cam groove 24d.

First, when the power supply of the driving device is closed prior to photographing, the light-emitting portion of the photo-interrupter 26 is turned on. At this time, the cylindrical rotating member is controlled by the signal level output from the photo-interrupter 26. It is determined whether 24 is at the proper initial position. Then, when the output level at that time is lower than the level corresponding to the stage Z1 in FIG. 2, the drive motor 3 is operated, and the cylindrical rotary member 24 in FIG. Rotate clockwise. Then, the light shielding area of the overhang portion 24b facing the optical path of the photo interrupter 26 gradually decreases, and the output level of the photo interrupter 26 increases. Then, when the output level reaches a level corresponding to the stage of Z1, the drive motor 3 is stopped, and the cylindrical rotary member 24 occupies a regular initial position.

Next, in photographing, the above-described zooming step (Z1 to Z5) is selected. Here, it is assumed that the zooming step 3 (Z3) is selected. When the shutter is released, first, the drive motor 3 rotates,
The cylindrical rotating member 24 is rotated clockwise in FIG. Therefore, since the light-shielding area of the overhang portion 24b gradually increases, the output level of the photointerrupter 26 decreases, and at the same time, the lens frame 11 is moved stepwise to the right in FIG. Lens frame 1
0 and 12 are also slightly moved accordingly. In FIG. 2, when the minimum level of the zooming stage 3 (Z3) is reached, only the lens frame 12 is moved, and when a predetermined level of the focus adjusting stage of F3 is detected, the drive motor 3 is stopped. , The position of each lens group is determined.

When the position of each lens group is determined in this manner, the motor 23 is energized to open and close the shutter blade 22. When the photographing is completed, the drive motor 3 is rotated again, and in FIG.
4 is rotated counterclockwise. Thereafter, when the output level of the photo-interrupter 26 reaches a level corresponding to the stage of variable magnification 1 (Z1), the drive motor 3 is stopped.
Accordingly, the cylindrical rotary member 24 is stopped at the proper initial position, and a series of operations is completed.

In the above description of the operation, if the cylindrical rotary member 24 is not at the proper initial position prior to photographing, the cylindrical rotary member 24 is temporarily reset in the same manner as in the prior art. In the present embodiment, the position of the cylindrical rotary member 24 is determined by the photo-interrupter 26 even when the cylindrical rotary member 24 is stopped. Therefore, it is possible to rotate the cylindrical rotating member 24 directly to a predetermined position from that position without returning to the initial position once. Therefore,
When adopting such a control method, after the end of shooting,
There is no need to return the cylindrical rotating member 24 to the initial position.

Second Embodiment Next, the structure of the second embodiment will be described with reference to FIG. In this embodiment, the cylindrical rotary member 24 in the first embodiment is divided into two parts, each of which is rotated by another drive mechanism. Therefore, other common members and parts are denoted by the same reference numerals as in the first embodiment, and description thereof will be omitted.

In this embodiment, another substrate 31 is provided in addition to the substrate 1. The substrate 1 and the substrate 31 are integrated by means not shown. Further, by appropriate means, the support plate 32 is provided on the subject side of the substrate 31, the drive motor 33 is provided on the image forming surface side,
Each is attached. A gear 34 is attached to an output shaft 33 a of the drive motor 33, and its rotation is reduced by gears 35 and 36 and transmitted to a gear 38 rotatably attached to a shaft 37. I have.

Two cylindrical rotating members 39 and 40 are rotatably fitted to the outer peripheral portion of the cylindrical fixing member 9. The cylindrical rotating members 39 and 40 have tooth portions 39a and 40, respectively, in the same manner as the cylindrical rotating member 24 of the first embodiment.
a and overhang portions 39b and 40b are formed, and the tooth portions 39
a, 40a mesh with the gears 8, 38; Further, another photo-interrupter 42 is attached to the substrate 31 by a screw 41, and the projecting portion 39 b of the cylindrical rotating member 39 is provided in the optical path of the photo-interrupter 26.
Is arranged, and the projecting portion 40b of the cylindrical rotating member 40 is arranged in the optical path of the other photo interrupter 42.

Although not explicitly shown, the cylindrical rotating member 4
0 is provided with two cam grooves for moving the lens frames 10 and 11 in the optical axis direction.
One cam groove is provided for moving the lens frame 12. Rollers 13, 14, and 15 are fitted in these cam grooves, respectively. However, in the first embodiment, since the lens frame 11 is moved stepwise in the optical axis direction, the shape of the cam groove 24d is formed in a step shape, and the shapes of the cam grooves 24c and 24e are also corresponding shapes. However, in this embodiment, in order to move the lens frame 11 continuously without moving the lens frame 11 stepwise, the shape of the cam groove into which the roller 17 is fitted has a shape in the optical axis direction. The other two cam grooves are formed so as to be continuously inclined.

As can be seen from the above description of the configuration, the zooming method of this embodiment is not a step zoom method. Also,
The second lens group for zooming and the fourth lens group for focus adjustment are moved by separate drive motors. The other points are the same as those of the first embodiment. Therefore, the operation of the present embodiment will be described in a simplified manner if it is the same as that of the first embodiment.

When the power supply of the driving device is closed prior to photographing, first, the photo interrupters 26 and 42 are energized. At this time, if the level of the output signal of each photo interrupter 26, 42 is lower than the level of each initial position shown in FIGS. To rotate the cylindrical rotating members 39 and 40 counterclockwise as viewed from the subject side. Thereby, the light-shielding area of the overhang portions 39b and 40b facing the optical paths of the photo interrupters 26 and 42 gradually decreases, and the output level of the photo interrupters 26 and 42 reaches the output level of each initial position. Then, the drive motors 3 and 33 are stopped, and the cylindrical rotary member 24 returns to the normal initial position. Incidentally, also in the case of this embodiment, this step is performed by
It is the same as the case of the first embodiment that it does not need to be adopted.

In this embodiment, unlike the first embodiment, the second lens unit for zooming can be moved before the shutter is released. That is,
In the case of this type of camera, there is a type in which the finder optical system is also of a variable magnification type (usually called a zoom finder). For this reason, in the case of the present embodiment, the zoom lens of the photographing optical system is also moved in conjunction with the photographer adjusting the magnification of the image frame of the subject by looking through the viewfinder. I have. Accordingly, although the relationship with the finder optical system is not particularly shown, the drive motor 33 is also a power source for moving the movable lens of the finder optical system. Therefore, the drive motor 33 is indispensable in such a camera, and the existence of the drive motor 33 does not constitute a disadvantage that compactness and cost are disadvantageous.

As described above, when the lens frame 11 is moved in conjunction with the finder optical system, the moving position of the lens frame 11 is determined at the time when the photographer has finished adjusting the magnification. Therefore, the signal output from the photo interrupter 42 as shown in FIG.
It is not used to determine the movement position of the lens frame 11 as in the embodiment, but is input as scaling information for the automatic focusing device. Next, when the shutter is released, the drive motor 3 rotates to rotate the cylindrical rotating member 39 clockwise from the initial position when viewed from the subject side, to move the lens frame 12, and to extend the projecting portion. 39
The light shielding area b gradually increases, and as shown in FIG. 6A, the output level of the photointerrupter 26 decreases. Then, when the output level reaches a level calculated based on the above-described variable power information and distance information, the drive motor 3 is stopped, and the position of the lens frame 12 is determined.

Thereafter, as in the case of the first embodiment, the opening and closing operation of the shutter blades 22 is performed by the motor 23, and the photographing ends. After photographing, drive motors 3 and 3
3 is rotated to return the cylindrical rotary members 39 and 40 to the initial position. However, as described in the description of the first embodiment, in the case of the configuration of the present embodiment, the cylindrical rotary members 39 and 40 are left as they are. It doesn't hurt at all. In the present embodiment, the description has been made on the assumption that the movement of the lens frame 11 is mechanically linked with the zoom finder and driven by one motor. However, the movement may be performed manually. If there is no limit on the number, both may be electrically linked. In a camera not provided with a zoom finder, the drive motor 33 can rotate only the cylindrical rotary member 40, or can rotate the cylindrical rotary member 40 manually.

In each of the above embodiments, the overhanging portion provided on the cylindrical rotary member is formed as a light-shielding wall that partially blocks the optical path of the photointerrupter. May be provided by continuously changing the transmitted light by the rotation of the cylindrical rotary member. In each of the above embodiments, a plurality of lens frames are moved.
The present invention is also applied to a case where one lens frame is moved. Therefore, in each of the above embodiments, only the focus adjustment may be performed, or only the zooming may be performed.

Further, in each of the above embodiments, the lens frame is disposed inside the cylindrical fixing member and the cylindrical rotating member is disposed outside the cylindrical fixing member. It may be arranged inside and the lens frame may be arranged outside. However, in this case, the axis provided on the lens frame is provided toward the center of the optical axis even in the radial direction as in each embodiment. Further, in the present invention, the tubular fixing member is not always necessary, and the present invention can be applied to the configuration of the type described in Japanese Patent Application Laid-Open No. 9-90452 described above. Further, the present invention is applied to various cameras, but is not limited to cameras, and can also be applied to various optical devices such as electric telescopes.

[0035]

As described above, according to the present invention, regardless of the position of the movable lens, the movable lens can be accurately moved by the motor to the predetermined position by one photoelectric detector. This is extremely effective in reducing the size and cost of optical devices.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration of a first embodiment.

FIG. 2 is a diagram illustrating a change in an output signal of a photointerrupter according to the first embodiment.

3 is a view of the cylindrical rotary member shown in FIG. 1 as viewed from the left side in FIG.

FIG. 4 is a development view of a cam groove formed in a peripheral surface of the cylindrical rotary member shown in FIG. 1 as viewed from an outer peripheral surface side.

FIG. 5 is a sectional view showing the configuration of the second embodiment.

FIG. 6 is for describing a second embodiment, and FIG.
6A is a diagram illustrating a change in an output signal from one photointerrupter (26), and FIG. 6B is a diagram illustrating a change in an output signal from the other photointerrupter (40).

[Explanation of symbols]

 1,31 Substrate 2,32 Support plate 3,33 Drive motor 3a, 33a Output shaft 4,5,6,8,34,35,36,38 Gear 7,16,17,18,37 Axis 9 Cylindrical fixing member 9a Flange 9b Hole 9c, 9d, 9e Long groove 9f, 24b, 39b, 40b Overhanging portion 10, 11, 12 Lens frame 13, 14, 15 Roller 19, 25, 41 Screw 20 Shutter base plate 21 Auxiliary base plate 22 Shutter blade 23 Motor 24, 39, 40 Cylindrical rotating member 24a, 39a, 40a Tooth portion 24c, 24d, 24e Cam groove 26, 42 Photo interrupter

Claims (4)

[Claims] 1. A cylindrical rotating member which is rotated about an optical axis by a motor, a lens frame having a lens mounted therein and which is moved in an optical axis direction when the cylindrical rotating member rotates, and a light receiving device. A photoelectric detector that outputs a signal of a level corresponding to the amount, and is provided on an outer peripheral portion of the cylindrical rotating member, facing a detection optical path of the photoelectric detector, and is rotated by the cylindrical rotating member. An overhang configured to continuously change the amount of light received by the photoelectric detector is provided, and a moving position of the lens frame is detected in accordance with a level of an output signal of the photoelectric detector. A lens driving device, characterized in that: 2. A tubular fixing member having at least one long groove is provided, at least one cam groove is provided on the cylindrical rotating member, and the lens frame has a radial direction. The lens driving device according to claim 1, wherein at least one protruding shaft portion is provided, and the shaft portion is fitted in both the long groove and the cam groove. 3. The apparatus according to claim 2, wherein said lens frame is arranged inside said cylindrical fixing member, and said cylindrical rotating member is arranged outside said cylindrical fixing member. The lens driving device as described in the above. 4. A light-shielding wall formed so that an overhang of the cylindrical rotary member gradually changes from an optical axis center over a predetermined rotation angle range of the cylindrical rotary member. The lens driving device according to any one of claims 1 to 3, wherein