JP2011138078A - Lens barrel and imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To further reduce the size and cost of a lens barrel while ensuring a sufficient speed reduction ratio. <P>SOLUTION: The lens barrel has: a drive motor 111 in which a rotation output shaft 111a is disposed to be substantially parallel to a plane vertical to an optical axis 20a; a first worm 112; a two-step gear 113 in which an intermediate spur gear 113a and a second worm 113b are formed; and a final spur gear 114 in which a rotation center axis is disposed to be substantially parallel to the optical axis 20a. The two-step gear 113 is disposed so that the axial line of the rotation center intersects with a plane vertical to the axial line of the rotation center of the first worm 112, at an angle corresponding to the lead angle of the first worm 112 and the lead angle of the intermediate spur gear 113a (refer to the lower right figure), and also intersects with a plane vertical to the axial line of the rotation center of the final spur gear 114, at an angle corresponding to the lead angle of the second worm 113b and the lead angle of the final spur gear 114 (refer to the intermediate figure). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a lens barrel and an imaging apparatus including a reduction drive unit that transmits a rotational drive force of a drive motor to a rotary ring via a plurality of reduction gears.

  2. Description of the Related Art Conventionally, an imaging apparatus such as a digital video camera or a digital still camera forms a subject image with an imaging lens, and a CCD (Charge Coupled Device Image Sensor) image sensor or a CMOS (Complementary Metal Oxide) disposed at the rear of the imaging lens. Semiconductor) A subject image is captured by an image sensor such as an image sensor. In order to perform a zooming operation and a focusing operation, an imaging apparatus is known in which an imaging lens can be moved in the optical axis direction in conjunction with the rotation of a rotating ring of a lens barrel.

  Here, in order to move the imaging lens, there is known a reduction drive unit that uses a drive motor as a drive source and rotationally drives a rotary ring by combining a plurality of reduction gears. In the conventional general reduction drive unit, the rotation output shaft of the drive motor is arranged parallel to the optical axis of the imaging lens, and the rotation center axis is arranged via a plurality of spur gears arranged parallel to the optical axis. The rotating ring was made to rotate.

JP-A-2005-300760

  However, the technique of Patent Document 1 described above is disadvantageous in reducing the size and cost of the lens barrel because many spur gears are required to obtain a required reduction ratio. Further, there is a problem that the rotation output shaft of the drive motor rotates due to reverse input of torque due to external force applied to the lens barrel unexpectedly. Therefore, since it is necessary to detect rotation by the sensor even when not driven, the addition of the sensor is disadvantageous for further downsizing and cost reduction. In addition, there is a problem of power loss because the sensor must be constantly energized.

  Therefore, a lens barrel is known in which the rotation output shaft of the drive motor is arranged parallel to a plane perpendicular to the optical axis of the imaging lens, and a worm wheel composed of a worm and a helical gear is provided on the drive motor side. ing.

FIG. 17 is a front view, a side view, and a perspective view showing a deceleration drive unit 210 in such a conventional lens barrel.
As shown in FIG. 17, the deceleration drive unit 210 includes a drive motor 211 in which a rotation output shaft 211a is arranged so as to be parallel to a plane perpendicular to the optical axis 200a of an imaging lens (not shown), and a rotation output shaft. A worm 212 fixed to 211a, and a plurality of gear groups 213 which mesh with the worm 212 and whose rotation center axis is disposed so as to be parallel to the optical axis 200a. The gear group 213 is meshed with the spur gear train 215a of the rotary ring 215 provided to be rotatable around the optical axis 200a, whereby the rotary ring 215 is rotated.

According to such a reduction drive unit 210, since the worm 212 having a large reduction ratio is used, the number of gears can be reduced as compared with the reduction drive unit described in Patent Document 1. For this reason, the length L2 of the speed reduction drive portion composed of the drive motor 211, the worm 212, and the gear group 213 can be reduced to some extent.
However, the lens barrel in the imaging apparatus is required to be further reduced in size and cost.

  Therefore, the problem to be solved by the present invention is to enable further downsizing and cost reduction of the lens barrel while ensuring a sufficient reduction ratio.

The present invention solves the above-described problems by the following means.
According to a first aspect of the present invention, there is provided a drive motor having a rotation output shaft disposed so as to be substantially parallel to a plane perpendicular to the optical axis of the imaging lens, a first worm fixed to the rotation output shaft, An intermediate gear that meshes with the first worm is formed on the input side, a two-stage gear that has a second worm that is coaxial with the intermediate gear is formed on the output side, and meshes with the second worm, and the light of the imaging lens A final gear having a rotation center shaft disposed so as to be substantially parallel to the shaft and a gear train meshing with the final gear are formed, and can be rotated about a rotation shaft substantially parallel to the optical axis of the imaging lens. The two-stage gear has an axis of rotation center that is perpendicular to a plane perpendicular to the axis of rotation of the first worm and the intermediate angle of the first worm and the intermediate gear. Pair with gear advance angle And a lens arranged so as to intersect at an angle corresponding to the advance angle of the second worm and the advance angle of the final gear with respect to a plane perpendicular to the axis of rotation of the final gear. It is a lens barrel.

  A seventh aspect of the invention is an image pickup apparatus including a drive motor, a first worm, a two-stage gear, a final gear, and a rotary ring similar to those of the first aspect of the invention.

(Function)
According to the first and seventh aspects of the present invention, the first worm fixed to the rotation output shaft of the drive motor and the intermediate gear meshing with the first worm are formed on the input side and coaxial with the intermediate gear. The second worm has a two-stage gear formed on the output side, and a final gear meshing with the second worm. Therefore, there are two worms (first worm and second worm) having a large reduction ratio, and the number of gears between the drive motor and the rotating ring can be further reduced as compared with the case of one worm. The two-stage gear is arranged such that the axis of rotation center is in a specific direction.

  According to the present invention, the number of gears between the drive motor and the rotating ring can be reduced. A two-stage gear is arranged in a specific direction. Therefore, the lens barrel can be further reduced in size and cost while ensuring a sufficient reduction ratio.

It is a front view which shows the structure of the digital still camera as one Embodiment of the imaging device of this invention. It is the perspective view and sectional drawing which show the lens barrel of the digital still camera shown in FIG. 1, and shows the retracted state at the time of non-photographing. FIGS. 2A and 2B are a perspective view and a sectional view showing a lens barrel of the digital still camera shown in FIG. It is the perspective view and sectional drawing which show the lens barrel of the digital still camera shown in FIG. 1, and shows the pay-out state at the time of tele photography. 1 is an exploded perspective view showing a main part of a lens barrel for a digital still camera as an embodiment of a lens barrel of the present invention. 1 is an exploded perspective view showing an example of a deceleration drive unit (first embodiment) in a lens barrel for a digital still camera as an embodiment of a lens barrel of the present invention. It is the perspective view and side view which show the two-stage gear of the deceleration drive unit shown in FIG. It is explanatory drawing of the lead angle of the 1st worm | warm of the deceleration drive unit in the lens barrel for digital still cameras as one Embodiment of the lens barrel of this invention, and a two-stage gear. It is explanatory drawing of the arrangement | positioning relationship which shows the structure (1st Embodiment) of the deceleration drive unit shown in FIG. It is explanatory drawing of the arrangement | positioning relationship which shows the structure (2nd Embodiment) of another deceleration drive unit in the lens barrel for digital still cameras as one Embodiment of the lens barrel of this invention. It is explanatory drawing of the arrangement | positioning relationship which shows the structure (3rd Embodiment) of another deceleration drive unit in the lens barrel for digital still cameras as one Embodiment of the lens barrel of this invention. It is explanatory drawing of the arrangement | positioning relationship which shows the structure (4th Embodiment) of another deceleration drive unit in the lens barrel for digital still cameras as one Embodiment of the lens barrel of this invention. It is explanatory drawing of the arrangement | positioning relationship which shows the structure (5th Embodiment) of another deceleration drive unit in the lens barrel for digital still cameras as one Embodiment of the lens barrel of this invention. It is explanatory drawing of the arrangement | positioning relationship which shows the structure (6th Embodiment) of another deceleration drive unit in the lens barrel for digital still cameras as one Embodiment of the lens barrel of this invention. It is explanatory drawing of the arrangement | positioning relationship which shows the structure (7th Embodiment) of another deceleration drive unit in the lens barrel for digital still cameras as one Embodiment of the lens barrel of this invention. It is explanatory drawing of the arrangement | positioning relationship which shows the structure (8th Embodiment) of another deceleration drive unit in the lens barrel for digital still cameras as one Embodiment of the lens barrel of this invention. It is the front view, side view, and perspective view which show the deceleration drive unit in the lens barrel of a prior art example.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
Here, the imaging device according to the present invention is assumed to be a digital still camera 10 in the following embodiments. The lens barrel in the present invention is assumed to be the lens barrel 20 for the digital still camera 10 in the following embodiments.
The description will be given in the following order:

1. First embodiment (lens barrel: configuration example of a deceleration drive unit)
2. Second embodiment (lens barrel: configuration example of another deceleration drive unit)
3. Third embodiment (lens barrel: configuration example of another deceleration drive unit)
4). Fourth embodiment (lens barrel: configuration example of another deceleration drive unit)
5. Fifth embodiment (lens barrel: configuration example of another deceleration drive unit)
6). Sixth embodiment (lens barrel: configuration example of another deceleration drive unit)
7). Seventh embodiment (lens barrel: configuration example of another deceleration drive unit)
8). Eighth embodiment (lens barrel: configuration example of another deceleration drive unit)

[External appearance of imaging device]

FIG. 1 is a front view showing a configuration of a digital still camera 10 as an embodiment of an imaging apparatus of the present invention.
As shown in FIG. 1, the digital still camera 10 includes a rectangular parallelepiped body 11 constituting an exterior. A lens barrel 20 is incorporated on the right side of the body 11. In the non-photographing state shown in FIG. 1, the front side of the lens barrel 20 is covered with the barrier unit 40.
In the digital still camera 10 shown in FIG. 1, the left and right refer to the left and right viewed from the front side shown in FIG.

  Further, for example, a strobe light emitting unit 12 is built in the upper left of the lens barrel 20, and for example, a switch unit 13 is built in the left of the strobe light emitting unit 12. Furthermore, on the right side of the lens barrel 20, for example, an AF (Auto Focus) auxiliary light unit 14 is incorporated, and on the left side of the lens barrel 20, for example, a battery 15 is incorporated. Furthermore, for example, a condenser microphone 16 is incorporated in the lower right of the lens barrel 20.

[External appearance of lens barrel]

2 is a perspective view and a cross-sectional view showing the lens barrel 20 of the digital still camera 10 shown in FIG. 1, and shows a retracted state at the time of non-photographing.
FIG. 3 is a perspective view and a cross-sectional view showing the lens barrel 20 of the digital still camera 10 shown in FIG. 1, and shows the extended state during wide shooting.
Furthermore, FIG. 4 is a perspective view and a cross-sectional view showing the lens barrel 20 of the digital still camera 10 shown in FIG.
As shown in FIGS. 2 to 4, the lens barrel 20 is a retractable type. The imaging optical system of the lens barrel 20 includes a first lens group 21, a second lens group 22 (corresponding to an imaging lens in the present invention), an automatic exposure device 24, and a third lens group 23 arranged in order from the subject side. , And the image sensor 25.
For example, a CCD image sensor or a CMOS image sensor is used as the image sensor 25.

  Here, the second lens group 22 is movable in a direction perpendicular to the optical axis 20a in order to realize a camera shake prevention function. The automatic exposure device 24 is a light amount adjustment device having a shutter function and an iris function. The automatic exposure device 24 is held so as to be relatively movable in the direction of the optical axis 20a and is urged in a direction away from the second lens group 22 by a spring 26. ing. 2, a part of the second lens group 22 is housed in the opening of the automatic exposure device 24 at the time of non-photographing, and at the time of photographing shown in FIGS. The second lens group 22 moves relatively away from the optical axis 20a. Therefore, the second lens group 22 is retracted from the opening of the automatic exposure device 24.

Further, the first lens group 21 is extended with respect to the imaging element 25 fixed in the direction of the optical axis 20a at the time of photographing shown in FIGS. Then, the zooming operation of the optical system is performed by moving the second lens group 22 by a predetermined amount in the direction of the optical axis 20a. Furthermore, the focusing operation of the optical system is performed by moving the third lens group 23 by a predetermined amount in the direction of the optical axis 20a. Further, the front side of the first lens group 21 is protected by the barrier unit 40 during non-photographing shown in FIG.
Note that the extension of the first lens group 21, the zooming operation by the movement of the second lens group 22, and the opening and closing of the barrier unit 40 are realized by control of a drive motor (not shown).

[Configuration example of lens barrel]

FIG. 5 is an exploded perspective view showing a main part of a lens barrel 20 for a digital still camera as an embodiment of the lens barrel of the present invention.
As shown in FIG. 5, the lens barrel 20 holds a makeup ring 31, a barrier cover 41, a pair of upper and lower barrier blades 42, a barrier drive spring 43, a barrier drive member 44, and the first lens group 21 in order from the subject side. A lens frame 32, a moving frame 33, a rectilinear guide ring 34, a rotating ring 35, a fixed ring 36, a rear barrel 37, and the like. The barrier cover 41 disposed in the front part of the first lens group 21 is formed with a photographing opening 41a for allowing light to enter the first lens group 21 and the like.
In FIG. 5, the second lens group 22 and the like shown in FIGS. 2 to 4 are not shown for convenience of explanation.

Here, the decorative ring 31 is fixed to the moving frame 33 to adjust the appearance of the lens barrel 20, and also protects the barrier unit 40 including the barrier cover 41, the barrier blade 42, the barrier driving spring 43, and the barrier driving member 44. To do. The decorative ring 31 is fixed by sticking a double-sided tape with release paper on the front surface of the barrier cover 41 fixed to the moving frame 33, peeling the release paper, and then covering the decorative ring 31 on the moving frame 33. And it is firmly fixed to the moving frame 33 via the barrier cover 41 by the adhesive force of the double-sided tape.
In addition, as a material of the decorative ring 31, various metals, such as an aluminum alloy and stainless steel, are suitable, but engineering plastics can also be used.

  The barrier unit 40 protects the photographing optical system by closing an optical path that is a photographing aperture when not photographing. Specifically, the barrier drive spring 43 attached between the barrier cover 41 and the barrier blade 42 and the barrier drive member 44 constitute an opening / closing mechanism for the barrier blade 42. The barrier driving member 44 drives the barrier blades 42 to open and close in accordance with switching between the photographing position and the standby position. Therefore, by switching (rotating) the barrier driving member 44 to the photographing position (open position, arrow B direction) or standby position (closed position, arrow A direction), the pair of barrier blades 42 supported to be rotatable are provided. Open and close. At the time of photographing, the barrier blade 42 that is disposed between the barrier cover 41 and the first lens group 21 and covers the opening 41a of the barrier cover 41 so as to be freely opened and closed opens the opening 41a, and the first lens group 21 and the like. Make light incident on. On the contrary, at the time of non-photographing, the barrier blade 42 is closed and the opening 41a is closed to protect the first lens group 21.

  The first lens group 21 is attached to a lens frame 32, and the lens frame 32 is held by a moving frame 33. The moving frame 33 is retracted or extended along the direction of the optical axis 20a according to the operation of the photographer. For this reason, the moving frame 33 is provided with cam pins at three locations, and engages with the three cam grooves provided on the inner peripheral side of the rotating ring 35 that can rotate around the optical axis 20a. ing. Further, the moving frame 33 is also engaged with the rectilinear groove of the rectilinear guide ring 34 so as not to be simultaneously rotated by the rotation of the rotating ring 35.

  Further, the rotation ring 35 and the straight guide ring 34 are bayonet-fitted, so that the straight guide ring 34 can be moved straight without being restricted with respect to the rotation of the rotary ring 35. Furthermore, with respect to the movement of the rotating ring 35 in the direction of the optical axis 20a, the linear guide ring 34 also moves together. Specifically, three cam pins are provided on the rotating ring 35 and are respectively fitted with three cam grooves provided on the inner peripheral side of the fixed ring 36. As the rotating ring 35 rotates with respect to the fixed ring 36, the rotating ring 35 moves in the direction of the optical axis 20a along the locus of the cam groove of the fixed ring 36. Further, the straight guide ring 34 has five convex portions for fitting with the fixed ring 36, and the five convex portions and the five straight grooves provided on the fixed ring 36 are respectively provided. Mating. Therefore, the linear guide ring 34 can only move in the direction of the optical axis 20a with respect to the fixed ring 36, and movement in the rotational direction is restricted.

  Therefore, when the rotating ring 35 is rotated, the rotating ring 35 moves in the direction of the optical axis 20 a while rotating with respect to the fixed ring 36. Further, the rectilinear guide ring 34 moves integrally with the rotating ring 35 in the direction of the optical axis 20a without rotating. Furthermore, the moving frame 33 moves in the direction of the optical axis 20a along the cam groove of the rotating ring 35 without rotating. As a result, the moving frame 33 moves in the direction of the optical axis 20a according to the rotation of the rotating ring 35 and its position, and retracts or extends. Further, the rear barrel 37 is held on the fixed ring 36, and the distance between the moving frame 33 and the rear barrel 37 is widened at the photographing position, and the distance between the moving frame 33 and the rear barrel 37 is widened at the standby position. It is becoming narrower.

  In addition, a cam surface 37 a is formed on the rear barrel 37, and this cam surface 37 a abuts on the cam surface 44 a formed on the barrier drive member 44. When the moving frame 33 is retracted and the distance from the rear barrel 37 is reduced, the barrier driving member 44 is gradually charged while the barrier driving spring 43 is gradually charged by the contact between the cam surface 37a and the cam surface 44a. Rotate in the A direction and close the barrier blade 42. Conversely, when the moving frame 33 is extended and the distance from the rear barrel 37 is increased, the cam surface 37a and the cam surface 44a are separated from each other, so that the charge of the barrier drive spring 43 is gradually released and the barrier drive member 44 is moved. It rotates in the direction of arrow B, and the barrier blade 42 is opened.

  In this way, the moving frame 33 is retracted or extended according to the rotation of the rotating ring 35 and its position to open and close the barrier blades 42. In the lens barrel 20 of the present embodiment, the second lens group 22 (see FIGS. 3 and 4) moves in the direction of the optical axis 20a in accordance with the rotation of the rotating ring 35 and the position thereof, and a zooming operation is performed. . Therefore, a gear train is formed on the outer peripheral surface of the rotary ring 35, and the rotary ring 35 is rotated by driving of a drive motor (not shown) fixed between the fixed ring 36 and the rear barrel 37. It is supposed to be. The rotational driving force of the drive motor is transmitted by a reduction drive unit that rotates the rotary ring 35 via a plurality of reduction gears.

<1. First Embodiment>
[Configuration example of deceleration drive unit in lens barrel]

FIG. 6 is an exploded perspective view showing an example deceleration drive unit 110 (first embodiment) in a lens barrel 20 for a digital still camera as an embodiment of the lens barrel of the present invention.
As shown in FIG. 6, the reduction drive unit 110 of the first embodiment has a drive motor 111, a first worm 112, a two-stage gear 113, and a final spur gear 114 (corresponding to the final gear in the present invention). is doing. The first worm 112, the two-stage gear 113, and the final spur gear 114 are engaged with each other, and the final spur gear 114 is a spur gear train 35a formed on a part of the outer peripheral surface of the rotating ring 35 (the gear in the present invention). (Equivalent to a row).
The spur gear train 35 a may be formed on the entire circumference of the rotating ring 35.

The drive motor 111, the two-stage gear 113, and the final spur gear 114 are respectively supported between the fixed ring 36 and the rear barrel 37, and the fixed ring 36 and the rear barrel 37 have four fastening screws 38. Fixed by.
Note that the stationary ring 36 and the rear barrel 37 are not only formed from a single member, but each may be divided into a plurality of members.

7 is a perspective view and a side view showing the two-stage gear 113 of the reduction drive unit 110 shown in FIG.
FIG. 8 is an explanatory diagram of the advance angle of the first worm 112 and the two-stage gear 133 of the deceleration drive unit in the lens barrel 20 for a digital still camera as an embodiment of the lens barrel of the present invention. .
In the two-stage gear 113 shown in FIG. 7, an intermediate spur gear 113a (corresponding to the intermediate gear in the present invention) and a second worm 113b are formed coaxially. And it is rotatably supported between the fixed ring 36 and the rear lens barrel 37.

  Further, the two-stage gear 133 shown in FIG. 8 has an intermediate helical gear 133a (corresponding to the intermediate gear in the present invention) and a second worm 133b formed coaxially, and the intermediate gear of the two-stage gear 113 shown in FIG. In this embodiment, the gear 113a is changed to an intermediate helical gear 133a. The two-stage gear 133 is not used in the reduction drive unit 110 of the first embodiment shown in FIG. 6, but is described for convenience of explanation of the advance angle.

  On the other hand, the first worm 112 shown in FIG. 8 is press-fitted and fixed to the rotation output shaft of the drive motor 111 (see FIG. 6), and rotates integrally with the rotation output shaft. The first worm 112 is provided with a light shielding blade 112a for detecting the rotational position of the rotary ring 35 (see FIG. 6). Specifically, when the light shielding blade 112a is rotated by the rotational drive of the drive motor 111, it moves forward and backward between the light projecting and receiving portions of a photo interrupter (not shown) held by the fixed ring 36 (see FIG. 6). Therefore, an electric signal pulse corresponding to the switching between light shielding and translucency is generated, and the electric signal pulse is counted corresponding to the rotation instruction direction of the control means, whereby the rotational position of the rotating ring 35 is detected.

The first worm 112 meshes with an intermediate spur gear 113a formed on the input side of the two-stage gear 113 shown in FIG. 7 or an intermediate helical gear 133a formed on the input side of the two-stage gear 133 shown in FIG. It has become. Furthermore, the second worm 113b formed on the output side of the second gear 113 or the second worm 133b formed on the output side of the second gear 133 is rotatable between the fixed ring 36 and the rear barrel 37. Is engaged with a final spur gear 114 (see FIG. 6) that is pivotally supported by the shaft.
The two-stage gear 113, the two-stage gear 133, and the final spur gear 114 are not directly supported between the fixed ring 36 and the rear barrel 37, but may be indirectly supported. . For example, a through hole is formed in the direction of the rotation center axis of the second gear 113, the second gear 133, or the final spur gear 114, a metal shaft is inserted into the through hole, and the metal shaft is inserted into the fixed ring 36 and the rear mirror. You may make it axially support with the cylinder 37. FIG.

Here, as shown in FIG. 8, the first worm 112 is formed with a worm advance angle α. The second worm 133b of the two-stage gear 133 is formed with a worm advance angle β. Furthermore, the intermediate helical gear 133a of the two-stage gear 133 is formed with a gear advance angle γ.
Note that the second worm 113b of the two-stage gear 113 shown in FIG. 7 also has the worm advance angle β, but the intermediate spur gear 113a has a case where the advance angle γ of the intermediate helical gear 133a is γ = 90 °. Can think.

Thus, the first worm 112, the second worm 113b, and the second worm 133b have an advance angle. The advance angle of the worm is as follows: m is the module of the worm, z is the number of strips, and d is the pitch circle diameter.
The advance angle of the worm is determined by sin ⁻¹ (m · z / d).
This indicates that the lead angle increases as (module m / pitch circle diameter d) increases and the number of worm stripes z increases. The worm has a feature of self-locking in which the worm cannot be rotated from the worm wheel side. For example, the first worm 112 cannot be rotated from the intermediate spur gear 113a or the intermediate helical gear 133a side, and this self-lock is generally more likely to occur as the advance angle α is smaller. Similarly, the second worm 113b and the second worm 133b cannot be rotated from the final spur gear 114 (see FIG. 6) side, and this self-locking is more likely to occur as the advance angle β is smaller.

  In the lens barrel 20 (see FIG. 1), the worm self-locking is performed by reversing the torque applied to the rotating ring 35 shown in FIG. 6 due to an external force from the user of the digital still camera 10 (see FIG. 1) or a drop impact. This means that the drive motor 111 does not rotate even if an input occurs. When the worm self-locking occurs, the rotation ring 35 does not rotate unexpectedly, so that the rotation detection mechanism of the deceleration drive unit 110 can be simplified. Specifically, the entrance / exit of the light shielding blade 112a (see FIG. 8) of the first worm 112 is detected by only one photo interrupter, and during operation, the rotation of the rotating ring 35 is performed by counting in the rotation instruction direction. You can know the position. Further, when not in operation, the power supply to the photo interrupter can be stopped.

  On the other hand, when the worm self-lock does not occur, the drive motor 111 rotates when reverse torque input to the rotary ring 35 occurs. Therefore, it is necessary to provide means for detecting the rotation direction and the rotation amount in order to correct the rotational position deviation. Specifically, in the method in which the entrance / exit of the light shielding blade 112a (see FIG. 8) is detected by a photo interrupter, it is necessary to provide two photo interrupters having a phase difference of 90 ° in order to detect the rotation direction. In addition, in order to prepare for unexpected rotation, it is necessary to always monitor the entrance / exit of the light shielding blade 112a by energizing the photo interrupter even during non-operation. As a result, there are disadvantages such as an increase in the size of the deceleration drive unit 110, an increase in cost, and an increase in power consumption by securing a space for providing two photo interrupters.

  Therefore, it is preferable to make the worm advance angle small so that self-locking is easily caused. However, in this case, there is a risk that the drive motor 111 bites. Biting occurs when a large frictional force remains between the worm and the worm wheel when the rotating ring 35 rotates in one direction and stops at the end of the spur gear train 35a in the rotating direction. Due to this bite, the starting torque of the drive motor 111 cannot return in the reverse direction.

Whether the worm self-locking or the biting of the drive motor 111 occurs is greatly influenced by the contact friction coefficient between the worm and the worm wheel in addition to the advance angle of the worm. The contact friction coefficient varies greatly depending on the surface state of the member, the type of lubricant, the state of application of the lubricant, the temperature characteristics of the lubricant, and the like, and is difficult to control.
From the above, when only a single worm is used, it is very difficult to realize both the worm self-locking and the biting prevention of the drive motor 111.

  Therefore, the deceleration drive unit 110 of the present embodiment uses two worms (first worm 112, second worm 113b, or second worm 133b) to prevent worm self-locking and prevention of biting of the drive motor 111. Both are compatible. Specifically, as shown in FIG. 8, the advance angle α of the first worm 112 is greater than the advance angle β of the second worm 133b (the same applies to the second worm 113b shown in FIG. 7). The first worm 112 on the input side prevents biting of the drive motor 111, and the second worm 133b (second worm 113b) on the output side realizes self-locking.

Further, the first worm 112 is a double thread, and the second worm 133b (second worm 113b) is a single thread. In this way, the first worm 112 is set to a double thread (set to a large advance angle α), so that the biting of the drive motor 111 hardly occurs. Further, the second worm 133b (second worm 113b) is a single thread (by setting it to a small advance angle β, thereby obtaining a large reduction ratio and at the same time generating a self-lock.
In the case of a lightly loaded lens barrel that may reduce the reduction ratio, the first worm may be a triple thread and the second worm may be a single thread or a double thread.

FIG. 9 is an explanatory diagram of the arrangement relationship showing the configuration (first embodiment) of the deceleration drive unit 110 shown in FIG.
As shown in FIG. 9, the reduction drive unit 110 of the first embodiment includes a drive motor 111, a first worm 112, a two-stage gear 113 (intermediate spur gear 113a, second worm 113b), and a final spur gear 114. It is constituted by.

  In such a deceleration drive unit 110, the drive motor 111 has a rotation output shaft 111a arranged in parallel with a plane perpendicular to the optical axis 20a. The first worm 112 is fixed to the rotation output shaft 111a. In the two-stage gear 113, an intermediate spur gear 113a meshing with the first worm 112 is formed on the input side, and a second worm 113b coaxial with the intermediate spur gear 113a is formed on the output side. Furthermore, the final spur gear 114 is meshed with the second worm 113b, and a rotation center axis is disposed so as to be parallel to the optical axis 20a. Further, the rotary ring 35 is formed with a spur gear train 35a that meshes with the final spur gear 114, and is rotatably provided around the optical axis 20a.

  Therefore, when the drive motor 111 is driven to rotate, the rotating ring 35 rotates through the two worms (the first worm 112 and the second worm 113b) having a large reduction ratio. Therefore, the number of gears between the drive motor 111 and the rotating ring 35 can be reduced while ensuring a sufficient reduction ratio, and the length L1 from the rear end portion of the drive motor 111 to the front end portion of the first worm 112 is reduced. it can. Specifically, L1 in the reduction drive unit 110 of the first embodiment shown in FIG. 9 is smaller than L2 in the reduction drive unit 210 of the conventional example shown in FIG. As a result, the lens barrel 20 (see FIG. 1) can be further reduced in size and cost. Since the strobe light emitting unit 12, the AF auxiliary light unit 14, the condenser microphone 16 and the like shown in FIG. 1 can be arranged close to the lens barrel 20 without a gap, the entire digital still camera 10 is downsized. .

  Further, in the reduction drive unit 110 of the first embodiment, since the intermediate spur gear 113a and the final spur gear 114 are used, the cost can be reduced compared to the case where the helical gear is used. Furthermore, the first worm 112 is a right-handed double thread, and the second worm 113b is a left-handed single thread. The advance angle α (see FIG. 8) of the first worm 112 is larger than the advance angle β (see FIG. 8) of the second worm 113b. For this reason, the first worm 112 on the input side not only prevents the drive motor 111 from biting, but also the second worm 113b on the output side causes self-locking.

  Here, as shown in the lower right diagram of FIG. 9 (a side view seen from the direction perpendicular to both the axis of the rotation center of the first worm 112 and the axis of the rotation center of the two-stage gear 113), the first worm 112 is shown. The angle at which the rotation center axis of the two-stage gear 113 intersects the plane perpendicular to the rotation center axis of the two-stage gear 113 is ζ (the same applies to the following embodiments). Further, as shown in the left diagram of FIG. 9 (a front view viewed from the objective side in the direction of the optical axis 20a), the axis of the rotation center of the first worm 112 and the rotation of the two-stage gear 113 on a plane perpendicular to the optical axis 20a. The central axis is projected, and at the intersection of the projection lines, the angle on the side where the final spur gear 114 exists is θ (the same applies to the following embodiments).

  In the reduction drive unit 110 of the first embodiment, the two-stage gear 113 has an advance angle of the first worm 112 with respect to a plane whose axis of rotation is perpendicular to the axis of rotation of the first worm 112. They are arranged so as to intersect at an angle corresponding to α (see FIG. 8) and the advance angle γ (see FIG. 8) of the intermediate spur gear 113a. Since the intermediate spur gear 113a has the advance angle γ = 90 °, the intermediate spur gear 113a is substantially arranged to intersect at an angle corresponding to the advance angle α of the first worm 112. Therefore, as shown in the lower right diagram of FIG. 9, the angle ζ = α.

  Further, as shown in the middle diagram of FIG. 9 (a side view seen from the direction perpendicular to both the axis of the center of rotation of the two-stage gear 113 and the axis of the center of rotation of the final spur gear 114), the two-stage gear 113 is The second spur gear 114 is arranged so that it intersects the plane perpendicular to the axis of rotation of the final spur gear 114 at an angle corresponding to the advance angle β of the second worm 113b (see FIG. 8) and the advance angle of the final spur gear 114. ing. Since the advance angle of the final spur gear 114 is 90 °, the final spur gear 114 is substantially arranged at an angle β corresponding to the advance angle β of the second worm 113b. Further, the two-stage gear 113 is formed so that the winding direction of the second worm 113b is counterclockwise so that the second worm 113b side of the axis of rotation center is inclined to the first worm 112 side in the optical axis 20a direction.

  Furthermore, when viewed from the objective side in the direction of the optical axis 20a (the left figure in FIG. 9), the two-stage gear 113 has a projection line of the axis of rotation center toward the second worm 113b. It arrange | positions so that the projection line of the axis line of the rotation center of the worm | warm 112 may intersect at an acute angle ((theta) 1). Therefore, the space S surrounded by a line connecting the tip of the second gear 113, the rotating ring 35, and the first worm 112 and the outer peripheral portion of the rotating ring 35 is effectively used, for example, a fastening screw 38 (FIG. 6) etc. can be arranged. Further, the rear end portion of the drive motor 111 can be brought closer to the optical axis 20a side.

Further, the final spur gear 114 is disposed in a region surrounded by the drive motor 111, the first worm 112, the second gear 113, and the rotating ring 35. Therefore, the angle θ = θ1 = acute angle, and the final spur gear 114 is disposed in the region on the acute angle side where the two projection lines intersect. As a result, useless space due to the arrangement of the final spur gear 114 does not occur.
The reason why θ1 = acute angle is that the advance angle α (see FIG. 8) and winding direction of the first worm 112 are set (right-handed).

<2. Second Embodiment>
[Configuration example of deceleration drive unit in lens barrel]

FIG. 10 is an explanatory diagram of an arrangement relationship showing the configuration (second embodiment) of another deceleration drive unit 120 in the lens barrel 20 for a digital still camera as an embodiment of the lens barrel of the present invention. It is.
The deceleration drive unit 120 of the second embodiment shown in FIG. 10 changes the winding direction of the first worm 122 in the reverse direction (left-handed) with respect to the deceleration drive unit 110 of the first embodiment shown in FIG. It is a form.
In addition, the same code | symbol is attached | subjected to the same member as the deceleration drive unit 110 of 1st Embodiment.

  In the reduction drive unit 120 of the second embodiment, when viewed from the objective side in the direction of the optical axis 20a (the left figure of FIG. 10), the two-stage gear 113 projects the axis of rotation center toward the second worm 113b. The line intersects the projection line of the axis of rotation center of the first worm 122 toward the drive motor 111 and an obtuse angle (θ = θ2 = obtuse angle).

  Further, as shown in the lower right diagram of FIG. 10, the two-stage gear 113 has an advance angle α (1) of the first worm 122 with respect to a plane whose axis of rotation is perpendicular to the axis of rotation of the first worm 122. 8) and the intermediate spur gear 113a intersect at an angle corresponding to the advance angle γ (see FIG. 8). The intermediate spur gear 113a substantially intersects at an angle corresponding to the advance angle α of the first worm 122 because the advance angle γ is 90 °. Therefore, the angle ζ = α (the direction of the angle ζ is opposite to that of the speed reduction drive unit 110 of the first embodiment shown in FIG. 9).

  Furthermore, as shown in the middle diagram of FIG. 10, the two-stage gear 113 has a final angle β (see FIG. 8) of the second worm 113b with respect to a plane perpendicular to the axis of rotation center of the final spur gear 114 and the final gear. They intersect at an angle corresponding to the advance angle of the spur gear 114. Since the advance angle of the final spur gear 114 is 90 °, the final spur gear 114 is substantially arranged at an angle β corresponding to the advance angle β of the second worm 113b. Further, the second gear 113 is tilted toward the first worm 122 in the direction of the optical axis 20a on the second worm 113b side of the axis of rotation center.

  In the deceleration drive unit 120 of the second embodiment as described above, the lens barrel 20 (see FIG. 1) can be further reduced in size and cost while ensuring a sufficient reduction ratio. However, in terms of space efficiency, the speed reduction drive unit 110 of the first embodiment shown in FIG. 9 is slightly inferior.

<3. Third Embodiment>
[Configuration example of deceleration drive unit in lens barrel]

FIG. 11 is an explanatory diagram of an arrangement relationship showing the configuration (third embodiment) of another deceleration drive unit 130 in the lens barrel 20 for a digital still camera as one embodiment of the lens barrel of the present invention. It is.
The speed reduction drive unit 130 of the third embodiment shown in FIG. 11 is opposite to the winding direction of the second worm 123b of the two-stage gear 123 with respect to the speed reduction drive unit 110 of the first embodiment shown in FIG. It is the form changed to (right-handed).
In addition, the same code | symbol is attached | subjected to the same member as the deceleration drive unit 110 of 1st Embodiment.

  In the reduction drive unit 130 of the third embodiment, when viewed from the objective side in the direction of the optical axis 20a (the left diagram in FIG. 11), the two-stage gear 123 projects the axis of rotation center toward the second worm 123b. The line intersects the projection line of the axis of rotation center of the first worm 112 toward the drive motor 111 at an acute angle (θ = θ3 = acute angle).

  Further, as shown in the lower right diagram of FIG. 11, the two-stage gear 123 has an advance angle α (1) of the first worm 112 with respect to a plane whose axis of rotation is perpendicular to the axis of rotation of the first worm 112. 8) and the intermediate spur gear 123a intersect at an angle corresponding to the advance angle γ (see FIG. 8). The intermediate spur gear 123a substantially intersects at an angle corresponding to the advance angle α of the first worm 112 because the advance angle γ = 90 °. Therefore, the angle ζ = α.

  Furthermore, as shown in the middle diagram of FIG. 11, the two-stage gear 123 has a lead angle β (see FIG. 8) of the second worm 123b with respect to a plane perpendicular to the axis of rotation center of the final spur gear 114. They intersect at an angle corresponding to the advance angle of the spur gear 114. Since the advance angle of the final spur gear 114 is 90 °, the final spur gear 114 is substantially arranged at an angle β corresponding to the advance angle β of the second worm 123b. However, since the second worm 123b is right-handed, the direction of the angle β is opposite to that of the reduction drive unit 110 of the first embodiment shown in FIG.

  In the deceleration drive unit 130 of the third embodiment as described above, the lens barrel 20 (see FIG. 1) can be further reduced in size and cost while ensuring a sufficient reduction ratio. However, in terms of space efficiency, the speed reduction drive unit 110 of the first embodiment shown in FIG. 9 is slightly inferior.

<4. Fourth Embodiment>
[Configuration example of deceleration drive unit in lens barrel]

FIG. 12 is an explanatory diagram of an arrangement relationship showing the configuration (fourth embodiment) of another deceleration drive unit 140 in the lens barrel 20 for a digital still camera as an embodiment of the lens barrel of the present invention. It is.
The deceleration drive unit 140 of the fourth embodiment shown in FIG. 12 changes the winding direction of the first worm 122 in the reverse direction (left-handed) with respect to the deceleration drive unit 110 of the first embodiment shown in FIG. In addition, the winding direction of the second worm 123b of the two-stage gear 123 is changed to the reverse direction (right-handed). The two-stage gear 123 is disposed on the objective side in the direction of the optical axis 20a with respect to the first worm 122.
In addition, the same code | symbol is attached | subjected to the same member as the deceleration drive unit 110 of 1st Embodiment.

  In the deceleration drive unit 140 of the fourth embodiment, when viewed from the objective side in the direction of the optical axis 20a (the left figure of FIG. 12), the two-stage gear 123 projects the axis of rotation center toward the second worm 123b. The line intersects the projected line of the axis of rotation center of the first worm 122 toward the drive motor 111 at an acute angle (θ = θ4 = acute angle).

  Further, as shown in the lower right diagram of FIG. 12, the two-stage gear 123 has an advance angle α (1) of the first worm 122 with respect to a plane whose axis of rotation is perpendicular to the axis of rotation of the first worm 122. 8) and the intermediate spur gear 123a intersect at an angle corresponding to the advance angle γ (see FIG. 8). The intermediate spur gear 123a substantially intersects at an angle corresponding to the advance angle α of the first worm 122 because the advance angle γ is 90 °. Therefore, the angle ζ = α.

  Furthermore, as shown in the middle diagram of FIG. 12, the two-stage gear 123 has a lead angle β (see FIG. 8) of the second worm 123b and a final angle with respect to a plane perpendicular to the axis of rotation of the final spur gear 114. They intersect at an angle corresponding to the advance angle of the spur gear 114. Since the advance angle of the final spur gear 114 is 90 °, the final spur gear 114 is substantially arranged at an angle β corresponding to the advance angle β of the second worm 123b. Further, the second gear 123 is tilted toward the first worm 122 in the direction of the optical axis 20a on the second worm 123b side of the axis of rotation center.

  In the deceleration drive unit 140 of the fourth embodiment as described above, the lens barrel 20 (see FIG. 1) can be further reduced in size and cost while ensuring a sufficient reduction ratio. And the space efficiency similar to the deceleration drive unit 110 of 1st Embodiment shown in FIG. 9 can be acquired.

<5. Fifth embodiment>
[Configuration example of deceleration drive unit in lens barrel]

FIG. 13 is an explanatory diagram of an arrangement relationship showing the configuration (fifth embodiment) of another deceleration drive unit 150 in the lens barrel 20 for a digital still camera as an embodiment of the lens barrel of the present invention. It is.
The deceleration drive unit 150 of the fifth embodiment shown in FIG. 13 changes the winding direction of the first worm 122 in the reverse direction (left-handed) with respect to the deceleration drive unit 110 of the first embodiment shown in FIG. In addition, the input side of the two-stage gear 133 that meshes with the first worm 122 is changed to an intermediate helical gear 133a.
In addition, the same code | symbol is attached | subjected to the same member as the deceleration drive unit 110 of 1st Embodiment.

  In the reduction driving unit 150 of the fifth embodiment, the advance angle γ of the intermediate helical gear 133a is 90 ° −α (a general worm wheel configuration at the advance angle α and the advance angle γ shown in FIG. 8). . The winding direction of the intermediate helical gear 133a is the same direction as the first worm 122 (left-handed). Therefore, when viewed from the objective side in the direction of the optical axis 20a (the left diagram in FIG. 13), the two-stage gear 133 has a first worm whose axis of rotation center line toward the second worm 133b is directed toward the drive motor 111. It intersects at right angles (θ = θ5 = 90 °) with the projected line of the axis 122 of the rotation center.

  Further, as shown in the right diagram of FIG. 13, the two-stage gear 133 has an advance angle α (1) of the first worm 122 with respect to a plane whose axis of rotation is perpendicular to the axis of rotation of the first worm 122. 8) and the intermediate helical gear 133a intersect at an angle corresponding to the advance angle γ (see FIG. 8). Since the advance angle γ of the intermediate helical gear 133a is 90 ° −the advance angle α of the first worm 122 (see FIG. 8), the angle ζ = 0 °.

  Furthermore, as shown in the middle diagram of FIG. 13, the two-stage gear 133 has a final angle β (see FIG. 8) of the second worm 133b with respect to a plane perpendicular to the axis of rotation center of the final spur gear 114. They intersect at an angle corresponding to the advance angle of the spur gear 114. Since the advance angle of the final spur gear 114 is 90 °, the final spur gear 114 is substantially arranged at an angle β corresponding to the advance angle β of the second worm 133b. Further, the second gear 133 is tilted toward the first worm 122 in the direction of the optical axis 20a on the second worm 133b side of the axis of rotation center.

  In the deceleration drive unit 150 of the fifth embodiment as described above, it is possible to further reduce the size and cost of the lens barrel 20 (see FIG. 1) while ensuring a sufficient reduction ratio. However, in terms of space efficiency, the speed reduction drive unit 110 of the first embodiment shown in FIG. 9 is slightly inferior.

<6. Sixth Embodiment>
[Configuration example of deceleration drive unit in lens barrel]

FIG. 14 is an explanatory diagram of an arrangement relationship showing the configuration (sixth embodiment) of another deceleration drive unit 160 in the lens barrel 20 for a digital still camera as an embodiment of the lens barrel of the present invention. It is.
In the deceleration drive unit 160 of the sixth embodiment shown in FIG. 14, the winding direction of the first worm 112 is reversed (right-handed) with respect to the deceleration drive unit 150 of the fifth embodiment shown in FIG. In addition, the lead angle γ (see FIG. 8) of the intermediate helical gear 143a (right-handed) of the two-stage gear 143 is changed to (90 ° −α) <γ <90 °.
In addition, the same code | symbol is attached | subjected to the same member as the deceleration drive unit 150 of 5th Embodiment.

In the reduction driving unit 160 of the sixth embodiment, when viewed from the objective side in the direction of the optical axis 20a (the left diagram in FIG. 14), the two-stage gear 143 projects the axis of rotation center toward the second worm 143b. The line intersects the projection line of the axis of rotation of the first worm 112 toward the drive motor 111 at an acute angle (θ = θ6 = acute angle). However, θ6 is larger than θ1 in the deceleration drive unit 110 of the first embodiment shown in FIG. 9 (θ1 <θ6 <90 °).
Note that θ6 can be made to be an obtuse angle by changing the first worm and the intermediate helical gear to the left-handed rotation with respect to the reduction drive unit 160 of the sixth embodiment. In this case, θ6 is smaller than θ2 in the deceleration drive unit 120 of the second embodiment shown in FIG. 10 (90 ° <θ6 <θ2).

  Further, as shown in the right diagram of FIG. 14, the two-stage gear 143 has a lead angle α (1) of the first worm 112 with respect to a plane whose axis of rotation is perpendicular to the axis of rotation of the first worm 112. 8) and the intermediate helical gear 143a intersect at an angle corresponding to the advance angle γ (see FIG. 8). The advance angle γ of the intermediate helical gear 143a is (90 ° −α) <γ <90 °. Therefore, the angle ζ calculated from the advance angle α of the first worm 112 and the advance angle γ of the intermediate helical gear 143a is 0 <ζ = α− (90 ° −γ) <α.

  Furthermore, as shown in the middle diagram of FIG. 14, the two-stage gear 143 has a lead angle β (see FIG. 8) of the second worm 143b with respect to a plane perpendicular to the axis of rotation of the final spur gear 114 and the final gear. They intersect at an angle corresponding to the advance angle of the spur gear 114. Since the advance angle of the final spur gear 114 is 90 °, the final spur gear 114 is substantially arranged at an angle β corresponding to the advance angle β of the second worm 143b. Further, the second gear 143 is tilted toward the first worm 112 in the direction of the optical axis 20a on the second worm 143b side of the axis of rotation center.

  In the deceleration drive unit 160 of the sixth embodiment as described above, the lens barrel 20 (see FIG. 1) can be further reduced in size and cost while ensuring a sufficient reduction ratio. However, in terms of space efficiency, the speed reduction drive unit 110 of the first embodiment shown in FIG. 9 is slightly inferior.

<7. Seventh Embodiment>
[Configuration example of deceleration drive unit in lens barrel]

FIG. 15 is an explanatory diagram of the arrangement relationship showing the configuration (seventh embodiment) of another deceleration drive unit 170 in the lens barrel 20 for a digital still camera as an embodiment of the lens barrel of the present invention. It is.
The reduction drive unit 170 of the seventh embodiment shown in FIG. 15 is opposite to the winding direction of the intermediate helical gear 153a of the two-stage gear 153 with respect to the reduction drive unit 160 of the sixth embodiment shown in FIG. (Left-handed) and the advance angle γ (see FIG. 8) is γ <90 °.
In addition, the same code | symbol is attached | subjected to the same member as the deceleration drive unit 160 of 6th Embodiment.

In the reduction driving unit 170 of the seventh embodiment, when viewed from the objective side in the direction of the optical axis 20a (the left diagram in FIG. 15), the two-stage gear 153 projects the axis of rotation center toward the second worm 153b. The line intersects the projection line of the axis of rotation center of the first worm 112 toward the drive motor 111 at an acute angle (θ = θ7 = acute angle). Moreover, θ7 is smaller than θ1 in the deceleration drive unit 110 of the first embodiment shown in FIG. 9 (θ7 <θ1 <90 °).
Note that θ7 can be made to be an obtuse angle by changing the first worm to the left-handed and the intermediate helical gear to the right-handed with respect to the reduction driving unit 170 of the seventh embodiment. In this case, θ7 is larger than θ2 in the speed reduction drive unit 120 of the second embodiment shown in FIG. 10 (90 ° <θ2 <θ7).

  Further, as shown in the right diagram of FIG. 15, the two-stage gear 153 has an axis of rotation center with respect to a plane perpendicular to the axis of rotation of the first worm 112. 8) and the intermediate helical gear 153a intersect at an angle corresponding to the advance angle γ (see FIG. 8). The advance angle γ of the intermediate helical gear 153a is γ <90 °. Therefore, the angle ζ calculated from the advance angle α of the first worm 112 and the advance angle γ of the intermediate helical gear 153a is ζ = α + (90 ° −γ)> α.

  Furthermore, as shown in the middle diagram of FIG. 15, the two-stage gear 153 has a lead angle β (see FIG. 8) of the second worm 153 b with respect to a plane perpendicular to the axis of rotation of the final spur gear 114 and the final gear 153. They intersect at an angle corresponding to the advance angle of the spur gear 114. Since the advance angle of the final spur gear 114 is 90 °, the final spur gear 114 is substantially arranged at an angle β corresponding to the advance angle β of the second worm 153b. Further, the second gear 153 has the axis of rotation center on the second worm 153b side inclined toward the first worm 112 side in the optical axis 20a direction.

  In the deceleration drive unit 170 of the seventh embodiment as described above, the lens barrel 20 (see FIG. 1) can be further reduced in size and cost while ensuring a sufficient reduction ratio. However, in terms of space efficiency, the speed reduction drive unit 110 of the first embodiment shown in FIG. 9 is slightly inferior.

<8. Eighth Embodiment>
[Configuration example of deceleration drive unit in lens barrel]

FIG. 16 is an explanatory diagram of an arrangement relationship showing the configuration (eighth embodiment) of another deceleration drive unit 180 in the lens barrel 20 for a digital still camera as an embodiment of the lens barrel of the present invention. It is.
The deceleration drive unit 180 according to the eighth embodiment shown in FIG. 16 reverses the positional relationship between the drive motor 111 and the two-stage gear 113 with respect to the deceleration drive unit 110 according to the first embodiment shown in FIG. It is a modified form.
In addition, the same code | symbol is attached | subjected to the same member as the deceleration drive unit 110 of 1st Embodiment.

In the deceleration drive unit 180 of the eighth embodiment as described above, a sufficient reduction ratio can be ensured. The lens barrel 20 is further reduced in size and cost by the arrangement of the strobe light emitting unit 12, the switch unit 13, the AF auxiliary light unit 14, the battery 15, the condenser microphone 16, and the like shown in FIG. Can do.
The reversal of the positional relationship as in the deceleration drive unit 180 of the eighth embodiment can be performed from the deceleration drive unit 120 of the second embodiment to the deceleration drive unit 170 of the seventh embodiment. is there. Also, a layout in which the reduction drive unit 110 of the first embodiment to all of the reduction drive units 180 of the eighth embodiment are rotated around the axis of the rotation center of the rotary ring 35, and the rotation of the rotary ring 35 is rotated. Layout with mirror image positional relationship with the plane including the central axis, layout with mirror image positional relationship with the plane perpendicular to the optical axis 20a including the axis of rotation center of the first worm 112, etc. The same effect can be obtained for the layout.

As mentioned above, although embodiment of this invention was described, this invention is not limited to embodiment mentioned above, The following various deformation | transformation are possible. For example,
(1) In the embodiment, the digital still camera 10 is taken as an example of the imaging device. However, the present invention is not limited to this, and can be widely applied to imaging devices such as digital video cameras and camera-equipped mobile phones.

  (2) In the embodiment, the rotation output shaft 111a of the drive motor 111 is arranged so as to be parallel to a plane perpendicular to the optical axis 20a, but may be substantially parallel. Further, in the embodiment, the rotation center axis of the final spur gear 114 is arranged to be parallel to the optical axis 20a, but may be substantially parallel. Furthermore, the final gear may be a helical gear instead of a spur gear.

  (3) In the embodiment, the first worm 112 or the like is a double thread, and the second worm 113b or the like is a single thread. However, the present invention is not limited to this. If the number of first worm stripes is 2 or more and the number of first worm stripes (advance angle α)> the number of second worm stripes (advance angle β), the erosion of the drive motor 111 will be described. Prevention of sticking and occurrence of self-locking can be realized. In the embodiment, the rotating ring 35 rotates around the optical axis 20a and moves in the direction of the optical axis 20a. However, the axis of rotation center of the rotating ring may not coincide with the optical axis, and the rotating ring may not move in the optical axis direction.

10 Digital still camera (imaging device)
20 Lens barrel 20a Optical axis 21 First lens group (imaging lens)
35 Rotating ring 35a Spur gear train (Gear train)
110 Deceleration drive unit (first embodiment)
111 Drive motor 112 First worm 113 Two-stage gear 113a Intermediate spur gear (intermediate gear)
113b Second worm 114 Final spur gear (final gear)
120 Deceleration drive unit (second embodiment)
122 First worm 123 Two-stage gear 123a Intermediate spur gear (intermediate gear)
123b Second worm 130 Deceleration drive unit (third embodiment)
133 Two-stage gear 133a Intermediate helical gear (intermediate gear)
133b Second worm 140 Deceleration drive unit (fourth embodiment)
143 Two-stage gear 143a Intermediate helical gear (intermediate gear)
143b Second worm 150 deceleration drive unit (fifth embodiment)
153 Two-stage gear 153a Intermediate helical gear (intermediate gear)
153b Second worm 160 Deceleration drive unit (sixth embodiment)
170 Deceleration drive unit (seventh embodiment)
180 Deceleration drive unit (8th embodiment)
210 Deceleration drive unit (conventional example)
211 Drive motor 211a Rotation output shaft 212 Worm 213 Gear group 215 Rotating ring 215a Spur gear train

Claims (7)

A drive motor having a rotation output shaft disposed so as to be substantially parallel to a plane perpendicular to the optical axis of the imaging lens;
A first worm fixed to the rotary output shaft;
An intermediate gear meshing with the first worm is formed on the input side, and a second gear having a second worm coaxial with the intermediate gear formed on the output side;
A final gear that meshes with the second worm and has a rotation center axis disposed substantially parallel to the optical axis of the imaging lens;
A gear train that meshes with the final gear, and a rotating ring that is rotatable about a rotation axis substantially parallel to the optical axis of the imaging lens,
The two-stage gear has an axis corresponding to the advance angle of the first worm and the advance angle of the intermediate gear with respect to a plane perpendicular to the axis of rotation of the first worm. And a lens barrel arranged to intersect at an angle corresponding to the advance angle of the second worm and the advance angle of the final gear with respect to a plane perpendicular to the axis of rotation center of the final gear. The lens barrel according to claim 1,
The first worm and the second worm are:
The first worm has two or more strips;
A lens barrel having a relationship of the number of first worm stripes> the number of second worm stripes and the advance angle of the first worm> the advance angle of the second worm. The lens barrel according to claim 1,
The intermediate gear is a spur gear or a helical gear. The lens barrel according to claim 1,
The final gear is disposed in a region surrounded by the drive motor, the first worm, the two-stage gear, and the rotating ring when viewed from the optical axis direction of the imaging lens. The lens barrel according to claim 1,
In the two-stage gear, the projection line onto the plane perpendicular to the optical axis of the axis of rotation center toward the second worm is projected onto the plane of the axis of rotation center of the first worm toward the drive motor. And are arranged to intersect at an acute angle,
The final gear is disposed in an acute angle region where the two projection lines intersect with each other. The lens barrel according to claim 1,
The two-stage gear is formed with a winding direction of the second worm so that the second worm side of the axis of rotation center is inclined toward the first worm side in the optical axis direction of the imaging lens. Tube. A drive motor having a rotation output shaft disposed so as to be substantially parallel to a plane perpendicular to the optical axis of the imaging lens;
A first worm fixed to the rotary output shaft;
An intermediate gear meshing with the first worm is formed on the input side, and a second gear having a second worm coaxial with the intermediate gear formed on the output side;
A final gear that meshes with the second worm and has a rotation center axis disposed substantially parallel to the optical axis of the imaging lens;
A gear train that meshes with the final gear, and a rotating ring that is rotatable about a rotation axis substantially parallel to the optical axis of the imaging lens,
The two-stage gear has an axis corresponding to the advance angle of the first worm and the advance angle of the intermediate gear with respect to a plane perpendicular to the axis of rotation of the first worm. An imaging device arranged to intersect at an angle corresponding to the advance angle of the second worm and the advance angle of the final gear with respect to a plane perpendicular to the axis of rotation center of the final gear.

Images