JP2007256320A - Lens drive device and imaging apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens drive device that allows a reduction in the thickness of an optical unit and to provide an imaging apparatus that satisfies a demand for a reduction in its thickness. <P>SOLUTION: The lens drive device includes: a plurality of lens holding means that hold a lens structure body and are movable in the direction of an optical axis within a lens barrel; drive devices that are provided for and drive the corresponding lens holding means; lead screws that are rotated by the drive devices and provided for the corresponding lens holding means such that the direction of the optical axis and the axial direction substantially coincide; a moving means that screws with each of the lead screws, thereby moving the corresponding lens holding means in the direction of the optical axis by the rotation of each lead screw. The drive devices that drive the lens holding means are parallelly arranged in the direction of the optical axis. The drive shafts are disposed substantially perpendicular to the axial directions of the corresponding lead screws. The drive shafts and the corresponding lead screw are connected by skew gears. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a lens driving device that moves a plurality of lens components along an optical axis, and an imaging device using the lens driving device.

In recent years, with the thinning of digital cameras and the like, the optical units mounted on these devices are also required to be thin.
As an optical system suitable for thinning the optical unit, there is a method of bending the optical axis by a mirror, a prism, or the like. In this case, the lens is arranged in a direction perpendicular to the thickness direction of the camera housing. Therefore, the increase in optical length does not affect the lens thickness. Therefore, the method of bending the optical axis is often applied to an optical unit having an optical zoom function that requires a long optical length.

  On the other hand, in an optical unit having an optical zoom function, it is necessary to move the zoom lens structure and the focus adjustment lens structure arranged in the optical unit while positioning with high accuracy. When driving the lens structure for zooming and the lens structure for focus adjustment by drive sources such as independent motors, the drive source and a speed reduction mechanism provided between the drive source and the lens structure are provided in the optical unit. How to arrange the optical unit is an issue for thinning the optical unit.

  Conventionally, for example, a technique for reducing the thickness of an optical unit and the area viewed from the thickness direction by arranging two motors alternately in the optical axis direction has been proposed (for example, Patent Document 1, Patent Document 2).

  In addition, a technology has been proposed that enables positioning with higher accuracy than a combination of only a stepping motor and a lead screw by connecting the rotating shaft of the stepping motor and the rotating shaft of the lead screw via a speed reduction mechanism. (For example, refer to Patent Document 3).

JP 2003-274628 A (summary column, FIG. 6) Japanese Patent Laying-Open No. 2005-326665 (FIGS. 5 and 6) JP 2001-215395 A (summary column, FIG. 1)

  When the motors are arranged alternately in the optical axis direction as in the techniques disclosed in Patent Document 1 and Patent Document 2, the thickness dimension is reduced compared to the case where the motors are arranged in the same direction in the optical axis direction. However, since there is a gap between the drive shafts, the optical unit thickness dimension is larger than the motor outer diameter. Moreover, since the position between the two motors is separated, the electrical wiring becomes complicated, and the wiring work becomes complicated.

  Further, since it is necessary to move the position of the lens structure to be moved away from the guide mechanism so that the outer diameter of the motor does not interfere, the rigidity of the coupling member between the guide mechanism of the lens structure and the drive mechanism is reduced, and as a result The operating characteristics of the lens structure deteriorate due to stick-slip caused by the frictional force of the guide mechanism and the elastic force of the coupling member.

  In addition, since the torque generated by the motor is affected by the number of windings, when the motor outer diameter is reduced as disclosed in Patent Document 1, the motor axial dimension increases or the generated torque increases. Get smaller.

  In Patent Document 3, a configuration using a speed reduction mechanism as a transmission mechanism between a motor and a lead screw is shown for improving positioning accuracy. However, the arrangement of the motor and the lead screw and the type of the speed reduction mechanism are specified. It is not intended to reduce the thickness of the lens driving device or the imaging device.

  An object of the present invention is to provide a lens driving device capable of reducing the thickness dimension of an optical unit. Another object of the present invention is to provide an imaging apparatus that satisfies the demand for thinning.

  The lens driving device according to the present invention is provided corresponding to each of the plurality of lens holding means, which holds the lens structure, and is provided so as to be movable in the optical axis direction in the lens barrel. A driving device that drives each of the corresponding lens holding means, and is provided so as to correspond to each of the lens holding means, and is provided so that the optical axis direction and the axial direction substantially coincide with each other. A lead screw that is rotationally driven; and a moving means that is screwed into each of the lead screws and moves the corresponding lens holding means in the optical axis direction by the rotation of each of the lead screws. Are arranged in parallel in the optical axis direction, and the drive shafts are respectively arranged in a direction substantially perpendicular to the axial direction of the corresponding lead screw. It is characterized in that the coupling by each discrepancy shaft gear between the lead screw to the corresponding to the drive shaft.

  An imaging apparatus according to the present invention includes a plurality of lens structures disposed in a lens barrel, a lens driving device that displaces at least some of the lens structures in the optical axis direction, and An imaging device comprising: an imaging element that displaces the lens structure in the optical axis direction by a lens driving device and receives an image of a formed subject on a light receiving surface, wherein the lens driving device includes the plurality of lens driving devices. A plurality of lens holding means provided so as to be movable in the direction of the optical axis while holding each of the lens components, and provided corresponding to each of the plurality of lens holding means. A drive device for driving each lens holding means and a drive device provided corresponding to each lens holding means, and provided so that the optical axis direction and the axial direction substantially coincide with each other, and are rotationally driven by the drive device. A driving device for driving the lens holding means, comprising: a screw screw; and a moving means that is screwed into each lead screw and moves the corresponding lens holding means in the optical axis direction by the rotation of each lead screw. Are arranged in parallel in the optical axis direction, the drive shafts are respectively arranged in a direction substantially perpendicular to the axial direction of the corresponding lead screw, and a staggered shaft gear is provided between the drive shaft and the corresponding lead screw. It is characterized by connecting.

  According to the present invention, the lead screw that drives the lens structure is arranged so that the rotation axis direction of the lead screw is the optical axis direction, and the staggered shaft gear is used as a drive transmission mechanism to the lead screw. Since the driving motors are arranged in parallel in the optical axis direction, the lens driving device can be thinned.

  According to another invention, by using the lens driving device, the thickness dimension of the optical unit can be reduced to the outer diameter of the motor, and an imaging device that satisfies the demand for thinning can be provided. .

  Preferred embodiments of a lens driving device according to the present invention and an imaging device using the same will be described below with reference to the accompanying drawings.

Embodiment 1 FIG.
1 to 4 illustrate the first embodiment, and FIG. 1 is a schematic plan sectional view of the imaging apparatus. As shown in FIG. 1, the imaging apparatus 100 includes a first lens structure 1, a second lens structure 2, a third lens structure 3, and an infrared light cut that blocks infrared light included in incident light. The image pickup device package 6 includes a filter 4 and an image pickup device 5. Here, the imaging element 5 is an element that can convert an optical image formed on the light receiving surface into an electric signal. In addition, a plurality of lens structures including the first lens structure 1, the second lens structure 2, and the third lens structure 3 are lenses that form an image of a subject on the light receiving surface of the image sensor 5. It is the member comprised by.

  The first lens structure 1 includes a first lens 7, a second lens 8 that is a prism lens, and a third lens 9, and is a first lens holding unit that holds these. The lens holding frame 10 is fixed to the lens barrel 11. The prism pressing member 14 and the image pickup device package 6 that are pressing members for the second lens 8 are each fixed to the lens barrel 11 together with the first lens component 1. The first lens structure 1 has a function of bending the optical axis in the vertical direction from the optical axis 12 to the optical axis 13 in FIG. 1, and as in the present embodiment, the first lens 7 The second lens 8 and the third lens 9 do not need to be constituted by a plurality of lenses, and have a function of bending the optical axis from the optical axis 12 to the optical axis 13 in FIG. If there is, it may be composed of one lens.

  The second lens structure 2 is a lens structure having a zooming function, that is, a variator, and changes the optical zoom magnification by operating in the optical axis direction. The second lens structure 2 includes an aperture stop 15 that limits the width of incident light, a fourth lens 16, and a fifth lens 17, and from the subject side toward the image sensor 5 side. The aperture stop 15, the fourth lens 16, and the fifth lens 17 are arranged in this order, and are held by a second lens holding frame 18 that is a second lens holding means. Note that the second lens structure 2 does not need to be composed of a plurality of lenses including the fourth lens 16 and the fifth lens 17 as in the present embodiment, and has a zooming function. If it is a thing, you may comprise with one lens.

  The third lens structure 3 is a lens structure having a focus adjustment function, that is, a compensator. The third lens structure 3 is operated in the optical axis direction in synchronization with the operation of the second lens structure 2. Is something that changes. The third lens structure 3 is composed of a sixth lens 19 and is held by a third lens holding frame 20 which is a third lens holding means. The second lens structure 2 and the third lens structure 3 are covered with the cover 21 and disposed in the lens barrel 11, and are guided by the guide shaft 22 and described below in the optical axis direction as will be described later. Is configured to move.

  The lens barrel 11, the first lens holding frame 10, the second lens holding frame 18, the third lens holding frame 20, the prism pressing member 14, the first lens 7, the second lens 8, Each of the third lens 9, the fourth lens 16, the fifth lens 17, and the sixth lens 19 is a plastic molded product, and is a mold formed by combining several cavities according to the part shape. It is manufactured by injecting and cooling thermoplastics inside. The guide shaft 22 is formed by grinding, and the deviation amount from the design value of the outer diameter dimension is suppressed to a high accuracy of about several μm.

FIG. 2 is a perspective view showing a lens driving device that drives the second lens structure 2 and the third lens structure 3 of the imaging apparatus 100.
As shown in FIG. 2, two guide shafts 22 are arranged in the imaging apparatus 100 so as to be separated from each other by a predetermined distance and parallel to each other. Further, the guide shaft 22 is disposed so as to be substantially parallel to the optical axis direction, and each of the second lens holding frame 18 and the third lens holding frame 20 uses the guide shaft 22 as a guide means as a guide shaft. 22 along the optical axis direction.

  The second lens holding frame 18 is applied with an urging force by a spring 23 that is an urging force applying means, and is in close contact with a nut 25 that is screwed into a lead screw 24 that has been subjected to a narrow pitch threading process. Is positioned. With this configuration, the position of the lead screw 24 in the optical axis direction is also restricted with respect to the lens barrel 11. That is, the spring 23 for bringing the second lens holding frame 18 into close contact with the nut 25 is a means for bringing the second lens holding frame 18 into close contact with the nut 25 and also serves as means for bringing the lead screw 24 into close contact with the lens barrel 11. Since both means are used, the number of parts can be reduced.

  Note that the second lens holding frame 18 is kept in close contact with the nut 25 while ensuring the degree of freedom other than in the optical axis direction by bringing the second lens holding frame 18 into close contact with the nut 25 using the spring 23. And high-precision positioning becomes possible. Further, by restricting the position of the lead screw 24 in the optical axis direction with respect to the lens barrel 11 using the spring 23, the lead screw 24 can be kept in close contact with the lens barrel 11 and positioning with high accuracy is possible. Become.

  Further, the second lens holding frame 18 is provided with a structure that restricts the rotation operation of the nut 25 around the lead screw 24. Note that the nut 25 and the second lens holding frame 18 do not need to be configured separately as in the present embodiment, and both may be formed as a single body, or may be configured as separate bodies. For example, the same effect can be obtained as an integrally configured structure such that the two are fixed and integrated by welding.

  A worm wheel 26 is fixed to the tip of the lead screw 24, and a stepping motor 27 having a drive shaft in a direction substantially orthogonal to the lead screw 24 is fixed to the fixing plate 28. The worm wheel 26 is configured to mesh with a staggered shaft gear fixed to the drive shaft end of the stepping motor 27, for example, a worm gear 29.

  With the above configuration, when the stepping motor 27 is driven, the lead screw 24 rotates via the worm gear 29 and the worm wheel 26, and the nut 25 screwed to the lead screw 24 moves in the axial direction of the lead screw 24, so that the second The lens holding frame 18 is moved in the optical axis direction. That is, the nut 25 functions as a moving unit for the second lens holding frame 18.

  The third lens holding frame 20 has substantially the same configuration as the second lens holding frame 18. That is, the third lens holding frame 20 is applied with an urging force by a spring 30 that is an urging force applying means, and comes into close contact with a nut 32 that is screwed into a lead screw 31 that has been subjected to narrow pitch threading. Positioned in the axial direction. With this configuration, the position of the lead screw 31 in the optical axis direction is also restricted with respect to the lens barrel 11. That is, the spring 30 for bringing the third lens holding frame 20 into close contact with the nut 32 is means for bringing the third lens holding frame 20 into close contact with the nut 32 and also means for bringing the lead screw 31 into close contact with the lens barrel 11. Since both means are used, the number of parts can be reduced.

  The third lens holding frame 20 is kept in close contact with the nut 32 while securing the degree of freedom other than in the optical axis direction by bringing the third lens holding frame 20 into close contact with the nut 32 using the spring 30. And high-precision positioning becomes possible. Furthermore, by restricting the position of the lead screw 31 with respect to the lens barrel 11 using the spring 30 in the optical axis direction, the lead screw 31 can always be brought into close contact with the lens barrel 11 and high-precision positioning is possible. Become.

  Further, the third lens holding frame 20 is provided with a structure that restricts the rotation operation of the nut 32 around the lead screw 31. Note that the nut 32 and the third lens holding frame 20 do not need to be configured separately as in the present embodiment, and may be formed as a single body, or may be configured as separate bodies. For example, the two may be integrally configured by fixing them together by welding.

  A worm wheel 33 is fixed to the tip of the lead screw 31, and a stepping motor 34 having a drive shaft in a direction substantially perpendicular to the lead screw 31 is fixed to the fixing plate 28. The worm wheel 33 is configured to mesh with a staggered shaft gear fixed to the drive shaft end of the stepping motor 34, for example, a worm gear 35.

  With the above configuration, when the stepping motor 34 is driven, the lead screw 31 rotates through the worm gear 35 and the worm wheel 33, and the nut 32 screwed to the lead screw 31 moves in the axial direction of the lead screw 31. The lens holding frame 20 is moved in the optical axis direction. That is, the nut 32 functions as a moving unit for the third lens holding frame 20.

  The worm wheel 33 fixed to the tip of the lead screw 31 is fixed at a position shifted in the optical axis direction by the outer diameter of the stepping motor 27 and drives the third lens component 3. The stepping motor 34 that is the source is arranged in parallel with the stepping motor 27 that is the driving source of the second lens component 2 in the optical axis direction. The driving source of the second lens structure 2 or the third lens structure 3 is not limited to the stepping motor, and other types of motors such as a coreless motor and an ultrasonic motor may be used.

  FIG. 3 is a side perspective view of the imaging apparatus 100. As can be understood from FIGS. 3 and 2, the lead screws 24 and 31 are restricted in the radial operation by a bearing 36 formed in the lens barrel 11. The springs 23 and 30 urge the second lens holding frame 18 and the third lens holding frame 20 to the nuts 25 and 32, and simultaneously urge the lead screws 24 and 31 to the lens barrel 11 to , 31 are positioned. The bearing 36, which is the positioning end of the lead screws 24 and 31 with respect to the lens barrel 11, is subjected to spherical processing so as to reduce the frictional force during the rotation of the lead screws 24 and 31. The spring 23 is guided by a spring guide 37 and the spring 30 is guided by a spring guide 38.

  The lens driving device according to the first embodiment and the imaging device using the lens driving device are configured as described above. Next, the operation thereof will be described.

  When the second lens structure 2 is operated, first, when the stepping motor 27 is operated at a necessary constant angle, the operating angle is transmitted to the worm gear 29 fixed to the drive shaft of the stepping motor 27 as the same amount of operating angle. The

  Next, the rotation angle of the worm gear 29 is transmitted at a reduction ratio designed for the worm wheel 26, and the operation angle of the worm wheel 26 is transmitted to the lead screw 24. Thereby, the nut 25 operates in the optical axis direction by the rotation angle of the lead screw 24 with respect to the thread pitch of the lead screw 24. By the operation of the nut 25, the second lens component 2 is guided by the guide shaft 22 in the optical axis direction together with the second lens holding frame 18 biased to the nut 25 by the spring 23. It will be displaced by the amount of movement.

Here, the rotation angle of the stepping motor 27 and the amount of movement of the nut 25 in the optical axis direction are expressed by the following relational expression.

  Next, the case where the 3rd lens structure 3 is operated is demonstrated. The case where the third lens structure 3 is operated is substantially the same as the case where the second lens structure 2 is operated. However, when the worm gear 35 and the worm wheel 33 constituting the driving device of the third lens structure 3 are the same as the worm gear 29 and the worm wheel 26 constituting the driving device of the second lens structure 2. 2, the positional relationship between the worm gear 35 and the worm wheel 33 is opposite to the positional relationship between the worm gear 29 and the worm wheel 26. Therefore, the rotational direction of the stepping motors 27 and 34 and the lens structure The relationship with the movement directions of a few will be reversed.

Therefore, the rotation angle of the stepping motor 34 and the amount of movement of the nut 32 in the optical axis direction in the driving device of the third lens structure 3 are expressed by the following relationship.

  As described above, in the lens driving device of the present embodiment, the springs 23 and 30 cause the first lens component 2 to be driven by the springs 23 and 30 during the operation of the second lens component 2 driving device or the third lens component 3 driving device. The second lens holding frame 18 and the third lens holding frame 20 are urged against the nuts 25 and 32, and the nuts 25 and 32 are urged by the threads formed on the lead screws 24 and 31. Will be. The lead screws 24 and 31 are restricted with respect to the lens barrel 11. As a result, since the clearance is always kept zero with respect to the optical axis direction, the second and third lens structures 2 and 3 are positioned with high accuracy in the optical axis direction.

Further, since the drive shafts of the motors 27 and 34 and the lead screws 24 and 31 are coupled by the worm gears 29 and 35, the reduction ratio can be increased, and the lens configuration can be achieved even if the output torque of the motors 27 and 34 is small. The bodies 2 and 3 can be moved. As a result, the number of windings of the motors 27 and 34 can be reduced, the motors 27 and 34 can be downsized, and the lens driving device can be downsized. The same effect can be obtained by using a screw gear or a hypoid gear instead of the worm gears 29 and 35.

  Furthermore, since stepping motors are used as the motors 27 and 34, sufficient positioning accuracy can be maintained even if the step angle is large, the structure of the motors 27 and 34 can be simplified, and complicated steps such as microstepping can be performed. It is not necessary to perform a simple motor control.

  Further, according to the imaging apparatus of the present embodiment, the dimension L in the thickness direction of the optical unit (see FIG. 3) is close to the outer diameter of the stepping motors 27 and 34, so that the optical unit can be thinned. . Therefore, it is possible to provide the imaging device 100 that satisfies the demand for thinning.

  Further, as shown in FIG. 4 which is a front perspective view of the imaging apparatus 100, the arrangement of the lead screws 24 and 31 is limited only by the outer diameter of the worm wheels 26 and 33 and the axial dimensions of the worm gears 29 and 35. Compared to the case where the drive shafts of the stepping motors 27 and 34 are simply arranged as lead screws, the position of the lead screw can be made closer to the guide shaft 22, and the lens component 2 by stick-slip 2 3 can reduce the deterioration of the operation characteristics.

  It should be noted that the present invention is not limited to the above-described embodiment, and it is obvious that the embodiment can be appropriately changed within the scope of the technical idea of the present invention.

  INDUSTRIAL APPLICABILITY The lens driving device and the imaging device using the lens driving device according to the present invention have great industrial applicability as a thin imaging device having a zoom function and an autofocus function in which a plurality of lens components move along the optical axis. It is.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic plan sectional view of an image pickup apparatus according to Embodiment 1 of the present invention that uses a lens driving apparatus according to Embodiment 1 of the present invention; It is a perspective view which shows the lens drive device by Embodiment 1 of this invention. 1 is a side perspective view of an imaging apparatus according to Embodiment 1 of the present invention. 1 is a front perspective view of an imaging apparatus according to Embodiment 1 of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st lens structure, 2 2nd lens structure 3 3rd lens structure 4 Infrared-light cut filter 5 Image sensor 6 Image sensor package 7 1st lens 8 2nd lens 9 3rd lens DESCRIPTION OF SYMBOLS 10 1st lens frame 11 Lens tube 12, 13 Optical axis 14 Prism pressing member 15 Aperture stop 16 4th lens 17 5th lens 18 2nd lens frame 19 6th lens 20 3rd lens frame 21 Cover 22 Guide shaft 23, 30 Spring 24, 31 Lead screw 25, 32 Nut 26, 33 Worm wheel 27, 34 Stepping motor 28 Fixing plate 29, 35 Worm gear 36 Bearing 37, 38 Spring guide 100 Imaging device

Claims (8)

A plurality of lens holding means provided to hold the lens structure and movable in the optical axis direction within the lens barrel;
A driving device provided corresponding to each of the plurality of lens holding means and driving each of the corresponding lens holding means;
A lead screw that is provided corresponding to each of the lens holding means, is provided so that the optical axis direction and the axial direction substantially coincide with each other, and is rotationally driven by the driving device;
Moving means for screwing into each of the lead screws and moving the corresponding lens holding means in the optical axis direction by rotation of each of the lead screws;
The driving devices for driving the lens holding means are arranged in parallel in the optical axis direction, and the driving shafts are arranged in directions substantially perpendicular to the axial directions of the corresponding lead screws, and the driving shafts and the corresponding lead screws. The lens drive device is characterized in that the two are connected with each other by a staggered shaft gear.   2. The lens driving device according to claim 1, wherein the lens holding unit and the lens moving unit are integrally configured.   The lens driving device according to claim 1, wherein the lens moving unit is sandwiched in the optical axis direction by a lens holding unit.   The lens driving device according to claim 1, further comprising an urging force applying unit that urges the lens holding unit with respect to the lens moving unit.   The lens driving device according to any one of claims 1 to 4, wherein a position of the lead screw in an optical axis direction with respect to a lens barrel is regulated.   6. The lens driving device according to claim 5, wherein the position of the lead screw in the optical axis direction with respect to the lens barrel is regulated by a biasing force applying unit that biases the lens holding unit against the lens moving unit.   The lens driving device according to claim 1, wherein the staggered shaft gear is a worm gear, a screw gear, or a hypoid gear. A plurality of lens structures disposed in the lens barrel;
A lens driving device that displaces at least some of the plurality of lens structures in the optical axis direction; and
An image sensor that displaces the lens structure in the optical axis direction by the lens driving device and receives an image of the imaged subject on a light receiving surface; and
An imaging apparatus comprising the lens driving device according to any one of claims 1 to 7.

Images