JP3837860B2 - Lens drive device for digital still camera - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a digital still camera, and more particularly to a lens driving device for a digital still camera.
[0002]
[Prior art]
The digital still camera is focused by using a stepping motor with a lead screw as a rotating shaft as a power source, the rotating shaft is installed parallel to the optical axis of the lens group, and a nut member screwed into the lead screw holds the lens group. The lead screw is rotated by the pulse drive of the stepping motor, and the lens group is moved according to the rotation angle to focus on the subject.
[0003]
Alternatively, the moving frame that holds the lens group has a hollow disk in which one end face is provided with a cam surface that contacts the moving frame, and a gear is installed on the inner or outer periphery of the hollow disk to rotate the pinion. The stepping motor on the shaft is used as the power source, the motor rotation shaft is installed in parallel with the optical axis of the lens group, the pinion and the hollow disk gear are meshed, and the pinion is rotated by the pulse drive of the stepping motor. A focusing drive device is known in which a hollow disk rotates according to a moving angle, a cam surface moves with the rotation of the hollow disk, and a focusing lens group moves to focus.
[0004]
[Problems to be solved by the invention]
In such a conventional technique, since the motor rotation axis and the optical axis are installed in parallel, it is difficult to reduce the thickness of the lens barrel in the optical axis direction.
[0005]
In the lead screw type, when the motor is used with two-phase excitation (generally, the number of divisions is 20), the lens movement amount in one pulse is determined by the lead screw lead. The amount of movement / pulse can be fine, but the screw thread is low, so it is necessary to mesh with many screw threads, the output torque of the motor is eaten by the nut part, and the torque for driving the lens is small . For this reason, when the lens weight is increased, the amount of movement / pulse cannot be reduced, resulting in a problem in focusing accuracy.
[0006]
In the hollow disk end face cam type, the motor output torque is decelerated by a pinion and a gear arranged around the hollow disk, so that it can be driven even when the weight of the focusing lens is heavy compared to the lead screw type. However, if the hollow disk is enlarged in order to increase the reduction ratio, the frictional force between the hollow disk and the hollow disk guide increases, resulting in torque loss. And there existed problems, such as a diameter of lens barrel itself becoming large.
[0007]
The present invention has been made to solve the above problems. That is, the lens barrel can be made thin in the optical axis direction, the lens performance is ensured, the motor output torque loss is reduced, the assemblability is improved, and the reference position detection of the lens group is performed with high accuracy. An object of the present invention is to provide a lens driving device and a digital still camera to be performed.
[0008]
[Means for Solving the Problems]
The object of the present invention is achieved by adopting the following configuration.
[0009]
That is, a driving source having a lens, a moving frame that holds the lens and moves the lens in the optical axis direction, a first contact portion provided in the moving frame, and an axis that extends in a direction different from the optical axis And a drive member provided on the shaft, and the second contact portion provided on the drive member, and the first contact portion as the drive member moves in the axial direction. A lens driving device for a digital still camera, wherein the lens moves in the optical axis direction when the contact position of the second contact portion changes.
[0010]
Further, in the lens barrel of a digital still camera having an exposure control device using an aperture / shutter and a focusing drive device for moving a lens group held by the exposure control device in the optical axis direction, the exposure control device Has a lens frame mechanism, and a lens is directly incorporated in the lens frame mechanism.
[0011]
Next, the operation of the present invention will be described.
[0012]
According to the first aspect of the present invention, since the power of the drive source is performed through the first contact portion and the second contact portion, the optical axis and the drive source axis are not set in the same direction. Furthermore, the occupation amount of the driving source in the optical axis direction with respect to the lens driving device is reduced, and the lens driving device can be made thin. Further, the power of the drive source is converted into the movement of the drive member in the axial direction, and the movement of the drive member in the axial direction is caused by a change in the contact position between the first contact portion and the second contact portion. By converting to movement in the optical axis direction, the output torque of the drive source can be used effectively.
[0013]
In the invention according to claim 2, the occupation amount of the driving source in the optical axis direction is only the thickness of the driving source in the optical axis direction, and the lens driving device can be further reduced in thickness .
[0014]
According to a third aspect of the present invention, the moving frame can be continuously moved in the optical axis direction by the cam surface that continuously changes.
[0015]
In the inventions according to claims 4 and 6, the loss of the output torque of the drive source can be kept low.
[0016]
The invention according to claim 5 uses the output torque effectively by arranging the axis of the drive source in parallel with the plane orthogonal to the optical axis of the lens and arranging the drive direction of the drive member in parallel with the plane. I can do it.
[0017]
In the invention according to claim 7, the lens can be moved in the optical axis direction by pulse driving.
[0018]
In the invention according to claim 8, the rotation operation of the drive source can be changed to the rectilinear operation of the drive member.
[0019]
In the invention according to the ninth aspect, the straightness of the nut member and the torque loss due to the fitting can be easily managed by the unit, and the assemblability is improved.
[0020]
In the invention according to claim 10, the movement of the moving frame in the optical axis direction can be used for the focusing operation of the lens.
[0021]
In the invention according to claim 11, the backlash does not occur due to the urging applied to the moving frame, and the lens can be moved accurately.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the accompanying drawings and FIGS. 1 to 5, but the present invention is not limited to the embodiments described below.
[0023]
FIG. 1 is an exploded perspective view from the front of members constituting a focusing drive device and a lens barrel of a digital still camera according to the present invention. FIG. 2 is a side view of the moving frame of the in-focus driving device and a driving member that moves the moving frame. FIGS. 3A and 3B are diagrams illustrating the configuration of a drive source that drives the drive member. FIG. 3A is a plan view of the drive source, and FIG. 3B is a front view of the drive source. 4A and 4B are diagrams for explaining the configuration of the lens barrel. FIG. 4A is a front view of the lens barrel, and FIG. 4B is a cross-sectional view taken along line XX in FIG. 5A and 5B are views for further explaining the lens barrel of FIG. 4, in which FIG. 5A is a front view of the lens barrel, and FIG. 5B is a cross-sectional view taken along the line XX of FIG.
[0024]
The focusing drive device for a digital still camera according to the first aspect of the present invention includes a guide shaft disposed in parallel with the optical axis of the lens group, and a fitting portion that is fitted to the guide shaft. A moving frame that holds the group and moves the lens group in the optical axis direction, and a drive member that has a cam surface against which the abutting portion of the moving frame moves the moving frame in the optical axis direction. Focus driving of a digital still camera, characterized in that the driving direction of the driving member and the rotation axis of the stepping motor installed in the driving source for driving the driving member are arranged in parallel to the plane orthogonal to the optical axis It is a device.
[0025]
That is, in FIGS. 1 to 4, the focusing drive device 1 of the present invention includes a moving frame 20, a lens fitting portion 20 e that is a lens frame mechanism of the moving frame 20, a first lens press 211, a lens interval ring 212, and The exposure control device 80 is provided with a lens fitting portion 80a which is a lens frame mechanism of the exposure control device 80, a lens interval ring 213, and a fifth lens presser 214, and the first lens 201 and the second lens 202 are provided in these lens frame mechanisms. The third lens 203, the fourth lens 204, and the fifth lens 205 that are bonded together are incorporated.
[0026]
The moving frame 20 has a guide shaft fitting sliding hole 20a that fits and slides on the guide shaft 40 that is incorporated in this manner and arranged parallel to the optical axis 3 of the lens group. The guide shaft 40 is fitted and fixed in the guide shaft fitting holes 30b and 10a of the main body lid 30 and the main body 10 as indicated by a one-dot chain line in the figure, and the guide shaft of the moving frame 20 is fitted as described above. The mating sliding hole 20 a is slidably fitted to the guide shaft 40, so that the moving frame 20 is urged downward by the downward urging force of the urging spring 50. Note that the U-shaped groove 20b of the moving frame 20 is fitted and slid with the moving frame rotation restricting portion 10b provided on the main trunk 10, so that the moving frame 20 can go straight without rotating. Yes.
[0027]
Then, as described above, the moving frame 20 that holds the lens group and moves the lens group in the direction of the optical axis 3 moves the driving member abutting portion 20g that is the abutting portion of the moving frame 20 over the cam surface. The drive member 60 has a drive member cam surface 60 d that is in contact with the biasing force of the biasing spring 50. Then, when the driving member 60 is driven by a driving source 70 described later, the moving frame 20 moves in the optical axis direction and is focused. The driving direction of the driving member 60 and the driving member 60 are The lead screw 70a directly connected to the rotation shaft of the stepping motor 70e installed in the driving source 70 to be driven is arranged in parallel with the plane orthogonal to the optical axis 3.
[0028]
Thus, since the focusing drive device of the present invention is configured, the occupation amount in the optical axis direction of the stepping motor is only the diameter of the stepping motor plus a slight margin and is directly connected to the lead screw of the conventional stepping motor. Unlike the case where the rotation axis is parallel to the optical axis, the lens barrel can be made thin.
[0029]
The angle of the drive member cam surface 60d with respect to the surface orthogonal to the optical axis 3 is preferably less than 45 degrees.
[0030]
The driving member 60 is inserted into the driving member linearly moving slide guide 10c, which is a rectangular concave portion of the main body 10, so as to be slidable in the longitudinal direction, and is pressed by the driving member pressing member 70f from above and is capped. It has become. The fitting slide portions 60a, 60b, and 60c of the driving member 60 are fitted and slidably guided by the driving member linearly moving slide guide 10c. The drive source 70 is attached to the drive source attachment portion 10 e of the main body 10.
[0031]
The drive source 70 has a rotation shaft directly connected to the lead screw 70a of a stepping motor 70e installed in the drive source 70, and a nut member guide shaft 70b of a guide shaft arranged in parallel to the rotation shaft. The nut member guide shaft 70b is fitted to the lead screw 70a, and the nut member 70c is screwed into the drive source. For this reason, it is possible to easily manage the straight loss of the nut member 70c and the torque loss due to the fitting by the unit, so that the drive source can be improved in assemblability.
[0032]
The driving member locking portion 70d of the driving source 70 is inserted into the driving source locking portion 60f of the driving member 60, and the driving member 60 is driven by the rotation of the stepping motor 70e. Since the cam surface 60d is at an angle of less than 45 degrees with respect to the surface orthogonal to the optical axis 3, the moving frame 20 can be easily moved by the driving force of the driving member 60 by the rotational force of the stepping motor 70e. is there. That is, the output torque by the arrangement of the stepping motor, and therefore the rotation axis of the lead screw that is directly connected to the rotation axis of the stepping motor, is arranged in parallel to the plane perpendicular to the optical axis of the lens group, and the drive direction of the drive member is also It arrange | positions so that it may become parallel to a surface, and it enables it to use output torque effectively by arrangement | positioning of such a stepping motor.
[0033]
The shape of the drive member contact portion 20g of the moving frame 20 that contacts the drive member cam surface 60d is preferably a spherical surface or a cylindrical surface. By adopting such a shape, the contact area can be reduced, and the loss of the output torque of the motor can be kept low.
[0034]
Moreover, it is preferable that the operating direction of the drive member 60 and the moving frame 20 at the time of focusing is focused in one operating direction. In the in-focus driving device of the digital still camera of the present invention, the number of pulses is calculated by back-calculating the number of pulses from the CCD non-focus signal at the time when it has passed a little from the time of focusing. As the movement of the lens, the lens moves forward slightly beyond the in-focus position, and after returning, the lens is moved forward by the number of in-focus pulses. That is, by always focusing in one operating direction in this way, backlash caused by the biasing spring 50 or the like applied to the moving frame 20 does not occur, and accurate focusing becomes possible.
[0035]
The drive member 60 is preferably made of a highly lubricious material, for example, a resin material such as polycarbonate (natural) or polyacetal. Since the frictional force generated on the contact surface can be reduced by using such a highly lubricious material, the loss of the output torque of the motor can be suppressed low.
[0036]
Further, the detection of the reference position of the lens group is detected by a detection sensor such as a photo interrupter 90 which is a reference position detection sensor, and the angle of the drive member cam surface 60d with respect to the plane orthogonal to the optical axis is less than 45 degrees. The detection of the reference position is preferably detected by the movement of the driving member 60, and is preferably detected by the movement of the moving frame 20 when the angle is 45 degrees or more. By doing in this way, it becomes possible to detect the position of the lens by a component having a large movement amount, and it is possible to detect the position of the lens accurately.
[0037]
This reference position is detected by driving the moving frame 20 so that the light shielding part 60e of the drive member 60 moves in focus to the concave part 90a of the photo interrupter 90 installed in the reference position detection sensor installation part 10f of the main cylinder 10. Inserted by driving the member 60, the reference position is detected. This reference position is determined as a reference position of the moving frame 20 at the ∞ position and the closest photographing position, and this reference position is a reference at the time of focusing. Therefore, the reference position is an important position as a focus reference, and accurate positioning is required. Therefore, it is preferable to detect the reference position with a component having a large movement amount.
[0038]
The lens barrel of the digital still camera of the present embodiment includes an exposure control device using an aperture / shutter, and a digital still camera having an in-focus drive device that moves a lens group held by the exposure control device in the direction of the optical axis. In this lens barrel, the exposure control device is provided with a lens frame mechanism, and the lens frame mechanism is directly incorporated into the lens frame mechanism.
[0039]
That is, in FIG. 1, FIG. 5, the lens barrel 2, the throttle function of controlling the brightness of the lens, the exposure control device 80 is a diaphragm-shutter having a sector 80e serving as a shutter function of controlling the exposure time, the exposure A lens barrel of a digital still camera having a focusing drive device that moves and focuses a lens group held by the control device 80 in the direction of the optical axis 3, and includes one of the exposure control device 80 and the exposure control device 80. The moving frame 20, which is also a part, is provided with lens fitting portions 20 e and 80 a that are lens frame mechanisms, a first lens holder 211, lens interval rings 212 and 213, and a fifth lens holder 214, and the first lens frame mechanism directly includes the first A lens barrel of a digital still camera characterized by incorporating a lens 201, a second lens 202, a third lens 203, a fourth lens 204, and a fifth lens 205 that are bonded together Going on.
[0040]
As described above, the lens barrel 2 of the present embodiment is configured, and the lens is directly incorporated into the exposure control device 80 having the aperture / shutter function. Therefore, this occurs when a lens frame incorporating the lens is further incorporated into the exposure control device. Accumulation of optical axis deviation can be reduced, and lens performance can be easily secured.
[0041]
The exposure control device 80 is provided with a flexible printed circuit board 80b for transmitting an electric signal for operating the aperture / shutter of the exposure control device 80. The flexible printed circuit board 80b is not bent in the thickness direction, and is connected to the connector of the camera body. It is a lens barrel of a digital still camera arranged to be connected to the camera. By doing so, it is suppressed that the flexible printed circuit board 80b has the spring property with the movement of the moving frame 20, and the driving force of the moving frame 20 is not consumed by the spring property. That is, in general, the flexible printed circuit board is used by being bent. In this case, the flexible printed circuit board 80b has a spring property as the moving frame 20 moves, and the driving force of the moving frame 20 is consumed by the spring property. However, this can be prevented.
[0042]
The flexible printed circuit board 80b is provided with a flexible printed circuit board locking hole 80c for enabling the movement of the flexible printed circuit board 80b accompanying the movement of the lens and the main body 10 constituting the lens barrel. A flexible printed board locking boss 10d for locking the printed board locking hole 80c is provided.
[0043]
Further, the main body lid 30 constituting the lens barrel which is also a cover of the exposure control device 80 and the main body 10 constituting the lens barrel are covered with the flexible printed circuit board 80b, and a flexible printed circuit board guard which is a protective member for protection. 30a and 10g are provided with a gap 11 at least capable of moving the lens. The gap 11 needs to be at least a distance from the reference position of the moving frame 20 described above to the closest photographing position. By doing so, it is possible to prevent an extra external force from being applied to the flexible printed circuit board 80b and to suppress a loss of output torque of the stepping motor 70e.
[0044]
【The invention's effect】
According to the present invention , the optical axis of the lens and the axis of the drive source can be configured not to be in the same direction, the lens drive device can be thinned in the optical axis direction, the lens performance is ensured, and the output torque of the drive source loss reduced to improve the assembling property, the lens driving equipment of a digital still camera for reference position detection of the lens group with high precision was to be provided.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view from a front direction of members constituting a lens driving device and a lens barrel.
FIG. 2 is a side view of a moving frame of the lens driving device and a driving member that moves the moving frame.
FIG. 3 is a diagram illustrating a configuration of a drive source that drives a drive member.
FIG. 4 is a diagram illustrating a configuration of a lens barrel.
5 is a view for further explaining the lens barrel of FIG. 4; FIG.
[Explanation of symbols]
1 lens driving device 2 lens barrel 3 optical axis 10 main barrel 20 moving frame 30 main barrel lid 40 guide shaft 50 biasing spring 60 driving member 70 driving source 80 exposure control device 90 photo interrupter

Claims (11)

A lens,
A moving frame for holding the lens and moving the lens in the optical axis direction;
A first contact portion provided on the moving frame;
A drive source having an axis extending in a direction different from the optical axis;
A drive member provided on the shaft;
The second contact portion provided on the drive member;
Have
As the drive member moves in the axial direction, the lens moves in the optical axis direction by changing the contact position of the first contact portion and the second contact portion. Lens drive device for digital still camera. 2. The lens driving device for a digital still camera according to claim 1, wherein the driving source is arranged so that the axis is arranged on a plane orthogonal to the optical axis. The second contact portion has a cam surface that continuously changes with respect to a plane orthogonal to the optical axis, and the first contact portion and the second contact portion move in the axial direction of the drive member. 2. The lens driving device for a digital still camera according to claim 1, wherein the lens moves in the optical axis direction when the contact position of the cam surface of the second contact portion changes.   4. The lens driving device for a digital still camera according to claim 1, wherein the shape of the first contact portion is a spherical surface or a cylindrical surface. 4. The lens driving device for a digital still camera according to claim 3, wherein an angle of the cam surface with respect to a surface orthogonal to the optical axis is less than 45 degrees.   The lens driving device for a digital still camera according to claim 1, wherein the driving member is made of a material having high lubricity.   The lens driving apparatus for a digital still camera according to claim 1, wherein the driving source includes a stepping motor.   The lens driving device for a digital still camera according to claim 1, wherein the shaft is a rotating shaft that forms a lead screw.   The drive source includes a stepping motor having a rotating shaft that forms a lead screw, a guide shaft disposed in parallel to the rotating shaft, and a nut member that is fitted to the guide shaft and screwed into the lead screw. The lens driving device for a digital still camera according to claim 1, wherein: 2. The lens driving device for a digital still camera according to claim 1, wherein the movement of the lens in the optical axis direction is a focusing operation.   2. The lens driving device for a digital still camera according to claim 1, wherein an operating direction of the driving member and the moving frame in accordance with the focusing operation is an operating direction of one direction.

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