The lens barrel includes a first frame, a second frame configured to be rotatably supported by the first frame, a drive actuator that is disposed on the inside of the second frame, and a transmission mechanism disposed on the inside of the second frame and configured to transmit the drive force of the drive actuator to the second frame. The imaging device includes the above-mentioned lens barrel and an imaging element that converts an optical image formed by this lens barrel into image data.
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1. A lens barrel that supports a lens, comprising:
a first frame;
a second frame configured to be rotatably supported by the first frame;
a drive actuator disposed on the inside of the second frame; and
a transmission mechanism disposed on the inside of the second frame and configured to transmit a drive force of the drive actuator to the second frame.
2. The lens barrel according to
a meshing part of the transmission mechanism is disposed near an inner peripheral part of the second frame.
3. The lens barrel according to
the transmission mechanism includes a drive gear that rotates the second frame, and
a meshing part of the transmission mechanism is disposed within a range whose radius is the distance from the rotational center of the second frame to a rotational center of the drive gear.
4. The lens barrel according to
the transmission mechanism further includes:
a first worm gear configured to be fixed to a rotary shaft of the drive actuator;
a first worm wheel configured to mesh with the first worm gear;
a second worm gear formed integrally with the first worm wheel, a rotational axis of the second worm gear coinciding with a rotational axis of the first worm wheel;
wherein a second worm wheel is configured to mesh with the second worm gear, and
the first worm wheel is disposed closer to a side of the second frame than the second worm gear.
5. The lens barrel according to
the relational formula 90°<θ≦110° is satisfied, θ defined by an obtuse angle formed by the rotational axis of the first worm wheel and a straight line connecting a rotational center of the second frame and a rotational center of a drive gear.
6. The lens barrel according to
the second frame includes a gear portion that protrudes to an inner peripheral side thereof,
a rotational axis of the second worm wheel and a rotational axis of a drive gear coinciding,
the gear portion is configured to mesh with the drive gear, and
the first worm wheel is disposed between the gear portion and the first worm gear along the rotational axis of the drive gear.
7. The lens barrel according to
the gear portion is disposed closer to a subject side than the first worm wheel, and
the second frame is driven by the transmission mechanism so as to move along the optical axis direction.
8. The lens barrel according to
at least one of the first worm wheel and the second worm wheel is a helical gear.
9. An imaging device, comprising:
the lens barrel according to
an imaging element configured to convert an optical image formed by the lens barrel into image data.
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This application claims priority under 35 U.S.C. §119 to Japanese Patent Application No. 2011-169854, filed on Aug. 3, 2011 and Japanese Patent Application No. 2012-128549, filed on Jun. 6, 2012. The entire disclosure of Japanese Patent Application No. 2011-169854 and Japanese Patent Application No. 2012-128549 are hereby incorporated herein by reference.
1. Technical Field
The technology disclosed herein relates to a telescoping lens barrel.
2. Background Information
Imaging devices that produce image data about a subject have rapidly gained popularity in recent years. A lens barrel for adjusting the focal distance is mounted in these imaging devices. Examples of known imaging devices include cameras with an integrated lens and those with an interchangeable lens. A lens barrel is built into an integrated type of camera. A camera with an interchangeable lens has a camera body and a lens barrel that can be mounted to the camera body.
A conventional lens barrel is disclosed in Japanese Laid-Open Patent Application H5-34563, for example. With this lens barrel, the focal distance can be adjusted, or the desired main subject can be focused on, by moving a lens group along the optical axis direction. A motor and a plurality of transmission gears are disposed in a substantially circular shape around the optical axis.
With respect to the lens barrel configuration discussed above, it has been discovered that there is a limit to how much the total length of the lens barrel can be reduced to achieve a more compact size, because the motor, the plurality of transmission gears, and a cam barrel are disposed aligned along the optical axis direction.
It is an object of the technology disclosed herein to provide a telescoping lens barrel that can be made more compact in its stowed state.
The lens barrel disclosed herein includes a first frame, a second frame, a drive actuator, and a transmission mechanism. The second frame is configured to be rotatably supported by the first frame. The drive actuator is disposed on the inside of the second frame. The transmission mechanism is disposed on the inside of the second frame and is configured to transmit the drive force of the drive actuator to the second frame.
With the above configuration, the drive actuator and the transmission mechanism can be efficiently disposed on the inside of the second frame, and the second frame can be disposed on the camera body side, so the lens barrel can be more compact.
Also, a similar reduction in size can be obtained with an imaging device comprising this lens barrel.
The technology disclosed herein makes it possible to provide a lens barrel and an imaging device that can be made more compact.
Referring now to the attached drawings, which form a part of this original disclosure:
Selected embodiments of the present technology will now be explained with reference to the drawings. It will be apparent to those skilled in the art from this disclosure that the following descriptions of the embodiments of the present technology are provided for illustration only and not for the purpose of limiting the technology as defined by the appended claims and their equivalents.
1. External Appearance
2. Vertical Cross Section of Lens Barrel 2
The outer frame 50 is fixed to the lens mount 80. The outer frame 50 supports the cam frame 60 rotatably and retractably along the optical axis direction. The outer frame 50 is a substantially cylindrical member. The fixed frame 70 is fixed to the lens mount 80.
The outer frame 50 is fixed by linking portions 51 (such as screws) to the lens mount 80. The linking portions 51 are inserted a specific length into the outer frame 50. More specifically, screws of a specific length are threaded into female threads formed inside the outer frame 50. Cam grooves 52 and rectilinear grooves 53 are formed in the inner peripheral face of the outer frame 50.
The cam frame 60 includes cam followers 66 on its outer peripheral face. The cam followers 66 engage with the cam grooves 52 formed in the inner peripheral face of the outer frame 50. Consequently, when the cam frame 60 rotates with respect to the outer frame 50, the cam followers 66 move along the cam grooves 52. As a result, the cam frame 60 advances and retracts with respect to the outer frame 50. First cam grooves 61 are formed in the outer peripheral face of the cam frame 60. Second cam grooves 62 are formed in the inner peripheral face of the cam frame 60.
As shown in
The cam frame 60 supports the first lens frame 21. First cam followers 31 are formed in the first lens frame 21. The first cam followers 31 engage with the first cam grooves 61. Consequently, when the cam frame 60 rotates with respect to the first lens frame 21, the first cam followers 31 move along the first cam grooves 61. As a result, the first lens frame 21 advances and retracts with respect to the cam frame 60. When the cam frame 60 has moved all the way to the lens mount 80 side, at least part of the first cam followers 31 of the first lens frame 21 is disposed within the region in which the linking portions 51 are disposed along the optical axis direction of the lens. The first lens frame 21 supports lenses L1, L2, and L3.
The cam frame 60 supports a second lens frame 22. Second cam followers 32 are formed on the second lens frame 22. The second cam followers 32 engage with the second cam grooves 62. Consequently, when the cam frame 60 rotates with respect to the second lens frame 22, the second cam followers 32 move along the second cam grooves 62. As a result, the second lens frame 22 advances and retracts with respect to the cam frame 60. The second lens frame 22 supports lenses L4, L5, L6, and L7. An aperture unit 42 is attached to the second lens frame 22, and moves integrally with the second lens frame 22 along the optical axis direction.
The cam frame 60 has a cylindrical main body. The cam frame 60 is disposed so that at least part of the main body of the cam frame 60 overlaps the contact face 81 as seen from the subject side.
The fixed frame 70 supports a third lens frame 23 via a shaft 71. The third lens frame 23 is driven along the optical axis direction by a focus motor (not shown). The third lens frame 23 supports a lens L8. The fixed frame 70 supports a lens L9. A stepping motor, for example, is used as the focus motor.
A motor 75 is fixed to the fixed frame 70. The motor 75 is disposed on the inner peripheral side of the cam frame 60. The motor 75 is a drive means for rotating the cam frame 60. At least part of the motor 75 is disposed within the region in which the linking portions 51 are disposed along the optical axis direction of the lens.
In this embodiment, an example was given in which the optical system was made up of four groups of lenses, but the present technology is not limited to this.
3. Cam Grooves
Screws 83 pass through the lens mount 80 and the fixed frame 70 and are inserted into the outer frame 50. This fixes the fixed frame 70, the lens mount 80, and the outer frame 50 to each other. The screws 83 and the linking portions 51 are each provided at three places.
As is clear from
The first cam grooves 61 and the cam followers 66 are provided to the outer peripheral face of the cam frame 60.
Cut-outs 65 are provided to the end of the cam frame 60 on the lens mount 80 side. The cut-outs 65 are provided at locations at the end of the cam frame 60 on the lens mount 80 side. In the location, the cut-outs 65 do not interfere with the first cam grooves 61 and the second cam grooves 62. Specifically, the cut-outs 65 are disposed at locations that are away from the first cam grooves 61 in the peripheral direction, and are disposed at locations that are away from the second cam grooves 62 along the optical axis direction.
4. Relation Between Cam Frame 60 and Fixed Frame 70
The meshing portions 101 and 102 are disposed on the inside of a circle whose radius is a distance r between the optical axis AX (the rotational center of the cam frame 60) and the rotational center of the drive gear 95, when the lens barrel 2 is viewed from the subject side. The first worm gear 91 is disposed at a location that is closer to the cam frame 60 than the second worm gear 93.
The gear portion 64, the first worm wheel 92, and the first worm gear 91 are disposed in that order starting from the subject side along the optical axis direction (see
As shown in
5. Conclusion
(1) The lens barrel 2 in a mode of the present technology includes the outer frame 50, the cam frame 60, the motor 75, and the transmission mechanism 76. The lens barrel 2 supports a lens. The cam frame 60 is disposed more to the inner peripheral side than the outer frame 50, and is supported rotatably with respect to the outer frame 50. The motor 75 is disposed on the inside of the cam frame 60. The transmission mechanism 76 is disposed on the inside of the cam frame 60, and transmits the rotational force of the motor 75 to the cam frame 60.
Consequently, the motor 75 and the transmission mechanism 76 can be disposed on the inner peripheral side of the cam frame 60, so the lens barrel can be smaller in diameter.
(2) With the lens barrel 2 in a mode of the present technology, the meshing portions 101 and 102 of the transmission mechanism 76 are disposed near the inner peripheral part of the cam frame 60.
This means that fewer gears are needed for the transmission mechanism 76, and the lens barrel can be made more compact.
(3) The lens barrel 2 in a mode of the present technology includes the outer frame 50, the cam frame 60, the motor 75, and the transmission mechanism 76. The lens barrel 2 supports a lens. The cam frame 60 is disposed more to the inner peripheral side than the outer frame 50, and is supported rotatably with respect to the outer frame 50. The motor 75 rotationally drives the cam frame 60 with respect to the outer frame 50. The transmission mechanism 76 transmits the drive force of the motor 75 to the cam frame 60. The transmission mechanism 76 includes the drive gear 95 that rotates the cam frame 60. The meshing portions 101 and 102 of the transmission mechanism are disposed on the inside of a circle whose radius r is the distance from the rotational center of the cam frame 60 to the rotational center of the drive gear 95.
This allows the motor 75 and the transmission mechanism 76 to be disposed on the inner peripheral side of the cam frame 60, so the lens barrel can be smaller in diameter.
(4) With the lens barrel 2 in this embodiment, the transmission mechanism 76 further has the first worm gear 91, the first worm wheel 92, the second worm gear 93, and the second worm wheel 94. The first worm gear 91 is fixed to the rotary shaft of the motor 75. The first worm wheel 92 meshes with the first worm gear 91. The second worm gear 93 is formed integrally with the first worm wheel 92 and the rotational axis of the second worm gear 93 coinciding with rotational axis of the first worm wheel 92.
The second worm wheel 94 meshes with the second worm gear 93. The first worm wheel 92 is disposed more to the cam frame 60 side than the second worm gear 93.
Consequently, the transmission mechanism 76 can be configured in a form that conforms to the inner peripheral face of the cam frame 60. Accordingly, the second lens frame 22 and so forth on the inside of the transmission mechanism 76 can be disposed more efficiently, and the lens barrel 2 can be smaller in diameter.
(5) With the lens barrel 2 of this embodiment, the conditional formula “90°<θ≦110°” is satisfied when the obtuse angle θ formed by the rotational axis of the first worm wheel 92 and a straight line connecting the rotational center of the drive gear 95 and the rotational center of the drive gear 95 in a plane that is perpendicular to the rotational axis direction of the cam frame 60.
This allows the transmission mechanism 76 to be configured as efficiently and small as possible, and to be disposed within the cam frame 60.
(6) With the lens barrel 2 in this embodiment, the cam frame 60 has a gear portion 64 that protrudes to the inner peripheral side, the second worm wheel 94 and the drive gear 95 share a rotational axis, the drive gear 95 meshes with the gear portion 64, and the first worm wheel 92 is disposed between the gear portion 64 and the first worm gear 91 in the rotational axis direction of the drive gear 95. Consequently, the gear portion 64 can be made smaller in diameter without inference by the first worm wheel with the gear portion 64, so a smaller lens barrel 2 can be obtained.
(7) With the lens barrel 2 in this embodiment, the gear portion 64 is disposed more to the subject side than the first worm wheel 92, and the cam frame 60 is driven by the transmission mechanism 76 so as to be able to advance and retract along the optical axis direction. This makes it possible for the cam frame 60 and the gear portion 64 to be moved to the subject side during imaging, so that the overall length of the lens barrel when not imaging can be reduced just as when the amount of movement of the various lens groups is increased.
(8) With the lens barrel 2 in this embodiment, the first worm wheel 92 and/or the second worm wheel 94 is a helical gear. If the first worm wheel 92 is a helical gear, the inclination of the second worm gear 93 as seen from the subject side can be greater than the lead angle α of the first worm gear 91. This makes it possible for the obtuse angle θ to satisfy the conditional formula 90°<θ≦110°. Also, if the second worm wheel 94 is a helical gear, the inclination of the second worm gear 93 along the optical axis direction can be made less than the lead angle β of the second worm gear 93. This allows the height of the transmission mechanism 76 to be reduced along the optical axis direction, so the lens barrel 2 can be more compact.
(9) With the imaging device 1 in this embodiment, the above-mentioned lens barrel 2 is mounted to the camera body 3 that includes an imaging element that captures an optical image formed by the lens barrel 2 and converts it into image data. This affords a more compact imaging device 1.
The present technology is not limited to or by the embodiments given above, and various modifications and alterations are possible without departing from the gist of the technology.
Those portions having substantially the same function as the portions in the first and second embodiments discussed above will be numbered the same and will not be described again in detail.
(1) In the above embodiments, an imaging device was described by using the imaging device 1 as an example, but the imaging device is not limited to being the imaging device 1. For example, the imaging device 1 can capture both still and moving pictures, but the imaging device may be one that captures only still pictures, or one that captures only moving pictures.
(2) In the above embodiments, a lens barrel was described by using the lens barrel 2 as an example, but the lens barrel is not limited to being the lens barrel 2. For example, the lens barrel may be one that is used in an integrated type of imaging device, rather than an interchangeable lens barrel.
(3) In the above embodiments, the motor 75 was described as an example, but the motor 75 is not limited to being a DC motor, and may instead be another type of motor (such as a stepping motor).
(4) In the above embodiments, the transmission mechanism 76 was constituted by a worm gear and a worm wheel, but may instead be constituted by a spur gear.
In understanding the scope of the present disclosure, the term “comprising” and its derivatives, as used herein, are intended to be open ended terms that specify the presence of the stated features, elements, components, groups, integers, and/or steps, but do not exclude the presence of other unstated features, elements, components, groups, integers and/or steps. The foregoing also applies to words having similar meanings such as the terms, “including”, “having” and their derivatives. Also, the terms “part,” “section,” “portion,” “member” or “element” when used in the singular can have the dual meaning of a single part or a plurality of parts. Also as used herein to describe the above embodiment(s), the following directional terms “forward”, “rearward”, “above”, “downward”, “vertical”, “horizontal”, “below” and “transverse” as well as any other similar directional terms refer to those directions of the lens barrel and the imaging device. Accordingly, these terms, as utilized to describe the present technology should be interpreted relative to the lens barrel and the imaging device.
The term “configured” as used herein to describe a component, section, or part of a device includes hardware and/or software that is constructed and/or programmed to carry out the desired function.
The terms of degree such as “substantially”, “about” and “approximately” as used herein mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed.
While only selected embodiments have been chosen to illustrate the present technology, it will be apparent to those skilled in the art from this disclosure that various changes and modifications can be made herein without departing from the scope of the technology as defined in the appended claims. For example, the size, shape, location or orientation of the various components can be changed as needed and/or desired. Components that are shown directly connected or contacting each other can have intermediate structures disposed between them. The functions of one element can be performed by two, and vice versa. The structures and functions of one embodiment can be adopted in another embodiment. It is not necessary for all advantages to be present in a particular embodiment at the same time. Every feature which is unique from the prior art, alone or in combination with other features, also should be considered a separate description of further technologies by the applicant, including the structural and/or functional concepts embodied by such feature(s). Thus, the foregoing descriptions of the embodiments according to the present technology are provided for illustration only, and not for the purpose of limiting the technology as defined by the appended claims and their equivalents.
The lens barrel described above allows for a reduction in size, and is therefore useful in the field of imaging devices.
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