JP4693797B2 - Lens drive device - Google Patents

Description

The present invention relates to a lens driving equipment to be mounted on an imaging apparatus such as a digital camera or a video camera.

  Conventionally, as a lens barrel of an imaging apparatus, the entire length is variable between an imaging state in which a plurality of lens groups are moved to perform zooming and focusing, and a storage state in which the lens interval and the interval between the imaging elements are narrowed to a predetermined interval. A retractable lens barrel is often used. Such a lens barrel is driven by a drive mechanism such as a cam, a helicoid, or a lead screw.

  Further, in recent years, with high functionality and high pixel count of imaging devices, high-speed, quiet lens driving and high-stop accuracy lens driving are required. For this reason, a mechanism for driving the lens group in the optical axis direction using a so-called voice coil motor in which a coil is disposed in a magnetic circuit composed of a magnet and a yoke instead of the DC motor and the stepping motor has been proposed.

  As a lens driving device using a voice coil motor, in order to reduce the weight of the lens holding member of the movable part, a coil is wound around the entire circumference of the lens holding member, and a magnet and a yoke are arranged on the fixed part. Has been proposed (Patent Document 1).

  On the other hand, in order to eliminate the complexity of wiring for supplying current to the coil when the coil is wound around the lens holding member of the movable part, the magnet is fixed to the lens holding member and the coil is wound around the fixed part. Have also been proposed (Patent Document 2).

Further, there has also been proposed a method in which a guide shaft that guides the lens holding member in the optical axis direction is a part of the yoke and a magnetic circuit is formed around the guide shaft (Patent Document 3).
Japanese Patent Laid-Open No. 7-239437 (FIG. 1) Japanese Patent Laying-Open No. 2006-65115 (FIG. 25) Japanese Patent No. 03767532 (FIG. 3)

  By the way, in a retractable lens barrel or the like, since a plurality of lens groups are driven by a substantially cylindrical drive mechanism such as a cam or a helicoid, when the voice coil motor is disposed inside the cylindrical body, the cylinder It is required to make the outer diameter of the body as small as possible.

  However, in Patent Document 1, since the coil is wound so as to surround the entire circumference of the lens holding member, and the magnet and the yoke are disposed so as to face the coil, the apparatus size is large over the entire circumference of the lens holding member. There is a problem of becoming.

  Further, in Patent Document 2, when a magnet is fixed to the lens holding member of the movable part, the weight of the lens holding member increases, so that a driving current necessary for driving the lens holding member increases. There is.

  Further, in Patent Document 3, when a magnetic circuit is formed around a guide shaft that guides the lens holding member in the optical axis direction as a part of the yoke, the lens and the magnetic circuit interfere with each other. It is necessary not to do. For this reason, there is a problem that the distance between the guide shaft and the lens must be relatively long, and the longitudinal dimension of the lens holding member becomes large.

The present invention aims to provide a lens driving equipment which can be arranged compactly by effectively utilizing the internal space of the barrel a voice coil motor which is disposed inside the barrel.

In order to achieve the above object, a lens driving device of the present invention includes a focus lens as a first lens group, a first lens holding member that holds a coil driven by a flexible substrate, and a second lens group. A second lens holding member that holds the first lens holding member, a guide shaft that guides the first lens holding member in the optical axis direction, and the first lens holding member that moves in the optical axis direction by the magnetic action of the coil. And a sensor for detecting the position of the first lens holding member in the optical axis direction, the fixing member holding the image sensor, and the second member fixed to the fixing member. comprising a cylindrical drive mechanism for moving the lens holding member in the optical axis direction, and the region between the viewed from the optical axis first lens holding member and the drive mechanism, the circumferential direction of the driving mechanism Along the coil, the magnet, and arranged the sensor in this order, characterized in that the flexible substrate arranged on the opposite side of the magnet relative to the coil.

  According to the present invention, since the voice coil motor arranged inside the lens barrel can be arranged compactly by effectively using the internal space of the lens barrel, the axial and radial dimensions of the lens barrel are large. Can be prevented.

  Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is an exploded perspective view for explaining a lens barrel of a lens driving apparatus as an example of an embodiment of the present invention, FIG. 2 is a sectional view of the lens barrel in a retracted state, and FIG. It is sectional drawing in the imaging state of a pipe | tube. This lens driving device is mounted on an imaging device such as a digital camera or a video camera.

  The lens barrel shown in FIG. 1 has a two-stage retractable three-group lens configuration, and a first group lens 101, a second group lens 102, and a third group lens 103 are arranged in this order from the subject side (left side in the figure). ing. The first group lens 101 is held by the first lens barrel 105, the second group lens 102 is held by the second lens barrel 106, and the third group lens 103 is held by the third lens barrel 107.

  The subject image that has passed through the three lens groups 101, 102, and 103 is photoelectrically converted by the image sensor 104 such as a CCD sensor or a CMOS sensor via the low-pass filter 110.

  The image sensor 104 is held by an image sensor base plate 109, and a cover barrel 111 is fixed to the image sensor base plate 109 by screws or the like. A drive cylinder 112 is rotatably held on the cover barrel 111 and the image sensor base plate 109.

  The drive cylinder 112 has a cylindrical shape, and the drive gear 113 is engaged with a gear 112 a provided on the outer periphery, and is driven to rotate by the rotation of the zoom motor 114. Further, three linear grooves 112b extending in the optical axis direction are formed in the inner peripheral wall of the drive cylinder 112 at equal intervals in the circumferential direction. Inside the drive cylinder 112, a fixed cylinder 115 fixed to the cover barrel 111 and the image sensor base plate 109 is disposed.

  In the fixed cylinder 115, three feed cams 115a each having a through groove shape are formed at equal intervals in the circumferential direction. Further, on the inner peripheral wall of the fixed cylinder 115, three feeding taper cams 115b are formed at equal intervals in the circumferential direction. Furthermore, three rectilinear grooves 115c extending in the optical axis direction are formed on the inner peripheral side of the fixed cylinder 115 at equal intervals in the circumferential direction. A movable cam cylinder 116 is disposed inside the fixed cylinder 115.

  The movable cam cylinder 116 has a cylindrical shape, and three follower pins 116a serving as cam followers are provided on the outer peripheral portion at equal intervals in the circumferential direction. Further, on the outer peripheral portion of the movable cam cylinder 116, three drive pins 116b are fixed at equal intervals in the circumferential direction. The drive pin 116b is located closer to the imaging surface than the follower pin 116a.

  A taper portion is formed at the tip of the follower pin 116 a, and the taper portion engages with a feeding taper cam 115 b of the fixed cylinder 115. Further, the drive pin 116b engages with the feeding cam 115a of the fixed cylinder 115 and also engages with the rectilinear groove 112b through the feeding cam 115a.

  When the drive cylinder 112 is rotated around the optical axis by the driving force of the zoom motor, the drive pin 116b is engaged with the rectilinear groove 112b, so that the follower pin 116a of the movable cam cylinder 116 is a tapered cam 115b of the fixed cylinder 115. It moves in the direction of the optical axis by lifting. A rectilinear cylinder 117 is disposed inside the movable cam cylinder 116.

  The rectilinear cylinder 117 has a cylindrical shape, and three protrusions 117a are provided at equal intervals in the circumferential direction on the outer peripheral portion on the rear end side. The protruding portion 117 a is engaged with a rectilinear groove 115 c formed on the inner peripheral side of the fixed cylinder 115. For this reason, the rectilinear cylinder 117 is movable in the optical axis direction with respect to the fixed cylinder 115, but is prevented from rotating around the optical axis.

  Protrusions 117 b are provided at three circumferentially equidistant positions on the outer periphery of the front end of the straight cylinder 117, and the protrusions 117 b are in contact with the front end of the movable cam cylinder 116. Therefore, when the moving cam cylinder 116 moves in the optical axis direction, the rectilinear cylinder 117 rotates in the optical axis direction integrally with the moving cam cylinder 116, but the rectilinear cylinder 117 does not rotate.

  The rectilinear cylinder 117 is formed with three through-groove rectilinear grooves 117c and 117d extending in the optical axis direction at equal intervals in the circumferential direction. Further, three tapered cams 116b and 116c are formed at equal intervals in the circumferential direction on the inner peripheral portion of the movable cam cylinder 116.

  On the other hand, three follower pins 105 a are provided at equal intervals in the circumferential direction on the outer periphery of the first barrel 105.

  The follower pin 105a passes through the rectilinear groove 117c of the rectilinear cylinder 117, and a tapered portion formed at the tip of the follower pin 105a is engaged with the taper cam 113b. Therefore, the first lens barrel 105 moves in the optical axis direction by the lift of the taper cam 113b in conjunction with the movement of the movable cam barrel 116 in the optical axis direction while rotating.

  Further, three cam followers 106 a are formed at equal intervals in the circumferential direction on the outer peripheral portion of the second lens barrel 106.

  The follower cam 106a passes through the rectilinear groove of the rectilinear cylinder 117, and a tapered portion formed at the tip of the follower cam 106a is engaged with the taper cam 113c. For this reason, the second lens barrel 106 moves in the optical axis direction by the lift of the taper cam 113c in conjunction with the movement of the movable cam barrel 116 in the optical axis direction while rotating. The second lens barrel 106 is equipped with a shutter / aperture unit 108 in addition to the second group lens 102.

  With the above configuration, the lens barrel is driven so as to change its entire length between the retracted state shown in FIG. 2 and the imaging state shown in FIG. In the imaging state, zooming can be performed by changing the distance between the three lens groups by the driving force of the zoom motor 114. Further, focusing can be performed by changing the position of the third group lens 103 in the optical axis direction by a voice coil motor described later.

  Next, a drive mechanism (focus drive mechanism) of the third group lens 103 using a voice coil motor as a drive source will be described.

  4 is an exploded perspective view of the driving mechanism of the third group lens 103 and the image pickup element base plate 109. FIG. 5 is an assembly view of the driving mechanism of the third group lens 103 and the image pickup element base plate 109.

  The voice coil motor includes a coil 118a, a magnet 118b, and a yoke 118c.

  The coil 118 a is fixed to the third lens barrel 107. When the coil 118 a is energized from the flexible substrate 119, the third lens barrel 107 moves along the guide shaft 121 by the action of a magnetic circuit formed by the magnet 118 b and the yoke 118 c fixed to the image sensor base plate 109 via the fixing member 120. Driven in the direction of the optical axis. Note that the driving range of the third lens barrel 107 is abutting between the third lens barrel 107 and the member 122 fixed to the image sensor main plate 109 with screws from the abutting surface of the image sensor main plate 109 and the third lens barrel 107. To the surface.

  The position of the third lens barrel 107 in the optical axis direction is detected by the sensor 123a and the scale 123b as follows.

  That is, the scale 123b is elastically held by the third lens barrel 107 by the elastic holding member 124. Grooves are formed in the scale 123b at a predetermined pitch. In addition, a sensor 123 a is attached to the imaging element base plate 109 by a fixing member 120 so as to face the scale 123 b with a predetermined gap interposed therebetween.

  A light emitting element and a light receiving element are mounted on the sensor 123a. A light beam emitted from the light emitting element is reflected by the groove of the scale 123b, and an output signal is obtained by receiving the reflected light beam by the light receiving element.

  When the third lens barrel 107 with the scale 123b fixed moves relative to the fixed sensor 123a, a sine wave signal having a phase difference of 90 deg is output from the sensor 123a. From these two-phase outputs, the movement amount and movement direction of the scale 123b can be determined. The initial position of the third lens barrel 107 is determined by abutment between the third lens barrel 107 and the image sensor base plate 109. The output of the sensor 123a may be three or more phases. Further, the phase angle may be an angle other than 90 degrees.

  Next, with reference to FIGS. 6 and 7, the layout of the coil 118a and the magnet 118b constituting the voice coil motor and the layout of the sensor 123a for detecting the position of the third lens barrel 107 in the optical axis direction will be described. .

  FIG. 6 is a view showing the driving mechanism of the third lens group 103 and the image sensor base plate 109 when the lens barrel is viewed from the optical axis direction (subject side), and FIG. 7 is a top view of FIG.

  When viewed from the optical axis direction, the voice coil motor and the sensor 123a are disposed close to the space between the third lens barrel 107 and the rectilinear cylinder 117.

  As shown in FIG. 7, the position of the sensor 123a in the optical axis direction is closer to the subject than the scale 123b, and the scale 123b requires a length (optical axis direction) longer than the moving range of the third lens barrel 107. For this reason, unless the scale 123b is positioned so as to penetrate the image sensor base plate 109, the sensor 123a is positioned at a distance equal to or larger than the moving range of the third lens barrel 107 from the image sensor base plate 109.

  Further, the height of the voice coil motor in the optical axis direction is at least a height in which the thickness of the coil 118a is added to the moving range of the third lens barrel 107. In a retractable lens barrel, for example, the protrusion of the second lens barrel 106 and the actuator of the shutter / aperture unit 108 may sink, so parts of the same height are placed close to each other so as not to interfere with them. It is desirable in terms of design. Therefore, in this embodiment, the voice coil motor and the sensor 123a are disposed close to each other.

  Further, the coil 118 a and the magnet 118 b of the voice coil motor are arranged substantially horizontally so that the opposing directions thereof are opposed to the circumferential direction of the rectilinear cylinder 117.

  8 and 9 are diagrams for explaining a layout example of the voice coil motor.

  The hatched portions in the figure are composed of a first barrel 105, a cover barrel 111 for driving the second barrel 106, a drive barrel 112, a fixed barrel 115, a moving cam barrel 116, a rectilinear barrel 117, and the like. Drive mechanism Z. A portion not hatched corresponds to the inside of the straight cylinder 117.

  FIG. 8 is a diagram showing a layout example in which the voice coil motor coil 118a and magnet 118b are arranged substantially vertically so that the facing direction of the coil 118a faces the radial direction of the rectilinear cylinder 117. FIG. 9 is a diagram showing a layout example in which the voice coil motor coil 118a and magnet 118b are arranged substantially horizontally so that the facing direction of the coil 118a faces the circumferential direction of the rectilinear cylinder 117.

  In the layout example of the voice coil motor in FIG. 8, since there are minimum dimensions that can be processed to the winding width of the coil 118a, the thickness of the magnet 118b, and the yoke 118c, the voice coil motor is partially enlarged in the radial direction of the straight cylinder 117. Become. As a result, the outer diameter of the lens barrel may increase.

  In addition, when the magnet 118b and the yoke 118c having a height in the voice coil motor are disposed immediately inside the rectilinear barrel 117, the first lens barrel 105 and the second lens barrel 106 that sink within the rectilinear barrel 117 are used. There is a possibility of interference with the outer cylinder. In particular, since the outer cylinder of the first lens barrel 105 may become an appearance in the imaging state, it is difficult to provide a notch for avoiding interference with the voice coil motor.

  In contrast, in the layout example of the voice coil motor in FIG. 9, the shapes of the coil 118a, the magnet 118b, and the yoke 118c can be changed in accordance with the inner diameter of the rectilinear cylinder 117, and the voice coil motor can be freely arranged. It is possible to set up.

  For this reason, in the present embodiment, the voice coil motor 118 and the magnet 118 b are disposed substantially horizontally so that the facing direction of the coil 118 a and the magnet 118 b are opposed to the circumferential direction of the rectilinear cylinder 117.

  As shown in FIGS. 6 and 10, the layout of the voice coil motor and the sensor 123a is arranged in the circumferential direction of the rectilinear cylinder 117 in the order of the coil 118a, the magnet 118b, and the sensor 123a.

  10, 11 and 12 are diagrams for explaining layout examples of the voice coil motor and the sensor 123a.

  In the figure, the hatched portion includes a first barrel 105, a cover barrel 111 for driving the second barrel 106, a drive barrel 112, a fixed barrel 115, a movable cam barrel 116, a rectilinear barrel 117, and the like. Drive mechanism Z. A portion not hatched corresponds to the inside of the straight cylinder 117.

  FIG. 10 is a diagram showing a layout example in which the coil 118a and the sensor 123a are arranged, and FIG. 11 is a diagram showing a layout example in which the magnet 118b and the sensor 123a are arranged. Further, as shown in FIG. 12, the sensor 123a can be laid out radially outside the rectilinear cylinder 117 of the voice coil motor. In this layout example, the rectilinear cylinder 117 is partially enlarged in the radial direction. Therefore, it is disadvantageous for downsizing of the lens barrel.

  The layout example shown in FIG. 10 has a problem that it is difficult to route the flexible substrate 119 for supplying a drive current to the coil 118a. As shown in FIG. 6, the flexible substrate 119 bends in a direction perpendicular to the optical axis when the third group lens 103 is located on the imaging surface side. For this reason, it is necessary to secure a space so that the flexible substrate 119 is not bent excessively so that a load is not applied to the movement of the third lens group 103 or the flexible substrate 119 is not damaged by interference with other components. There is.

  For this reason, in the present embodiment, a layout in which the magnet 118b and the sensor 123a are arranged as shown in FIG. 11 is employed in order to facilitate the routing of the flexible substrate 119.

  In the present embodiment, as shown in FIGS. 13A and 13B, the flexible substrate 119 is stored so as not to interfere with the second group lens 102 in the retracted state. In the photographing state, the space formed by the movement of the second lens barrel 106 is used to secure a space so that the flexible substrate 119 does not interfere even if the third lens barrel 107 moves.

  As described above, in this embodiment, the coil 118a, the magnet 118b, and the sensor 123a of the voice coil motor are disposed between the third lens barrel 107 and the drive mechanism Z, and the opposing direction of the coil 118a and the magnet 118b is that of the drive mechanism Z. They are arranged almost horizontally so as to face each other in the circumferential direction.

  As a result, the voice coil motor disposed inside the lens barrel can be disposed compactly by effectively using the internal space of the lens barrel, and the axial and radial dimensions of the lens barrel are increased. Can be prevented.

  In addition, since the magnet 118b and the sensor 123a are arranged close to each other, the flexible substrate 119 can be easily routed, and the sensor 123a is simultaneously fixed by the fixing member 120 for fixing the magnet 118b to the image pickup device base plate 109. can do.

  As a result, the number of parts such as fixing members and screws for fixing the sensor 123a can be reduced, the space necessary for fixing can be saved, and the lens barrel can be reduced in size. .

  In addition, this invention is not limited to what was illustrated to the said embodiment, In the range which does not deviate from the summary of this invention, it can change suitably.

  For example, in the above embodiment, the focus lens group (the third group lens 103) is driven by the voice coil motor. However, the present invention is not limited to this, and any other lens group driven by the voice coil motor may be used. The present invention may be applied to these lens groups.

  In the above-described embodiment, a two-stage collapsible type lens barrel having a three-group lens structure is illustrated. A lens configuration other than the three-group lens configuration may be used.

  Furthermore, in the above embodiment, the case where the voice coil motor and the sensor are arranged between the third lens barrel 107 and the rectilinear barrel 117 is illustrated, but the present invention is not limited to this, and the innermost lens barrel is present. The present invention can be applied to a substantially cylindrical drive mechanism.

It is a disassembled perspective view for demonstrating the lens barrel of the lens drive device which is an example of embodiment of this invention. It is sectional drawing in the retracted state of the lens-barrel shown in FIG. It is sectional drawing in the imaging state of the lens-barrel shown in FIG. It is a disassembled perspective view for demonstrating the drive mechanism of a 3 group lens. It is an assembly diagram for explaining a drive mechanism of the third group lens. It is the figure which looked at the drive mechanism of a 3 group lens from the optical axis direction (object side) of the lens barrel. FIG. 7 is a top view of FIG. 6. It is a figure for demonstrating the example of a layout of a voice coil motor. It is a figure for demonstrating the example of a layout of a voice coil motor. It is a figure for demonstrating the example of a layout of a voice coil motor and a sensor. It is a figure for demonstrating the example of a layout of a voice coil motor and a sensor. It is a figure for demonstrating the example of a layout of a voice coil motor and a sensor. (A) is a figure for demonstrating the state of the flexible substrate in the retracted state of a lens barrel, (b) is a figure for demonstrating the state of the flexible substrate in the imaging state of a lens barrel.

Explanation of symbols

101 1 group lens (2nd lens group)
102 2 group lens 103 3 group lens (1st lens group)
104 Image sensor 105 First lens barrel (second lens barrel)
106 Second lens barrel 107 Third lens barrel (first lens barrel)
108 Shutter / aperture unit 109 Image sensor base plate (fixing member)
110 Low-pass filter 111 Cover barrel 112 Drive cylinder 112a Gear section 112b Straight groove 113 Drive gear 114 Zoom motor 115 Fixed cylinder 115a Feed cam 115b Feed taper cam 115c Straight groove 116 Moving cam cylinder 116a Follower pin 116b Drive pin 117 Straight cylinder 117a Projection 117b Protrusion 117c Straight groove 117d Straight groove 118a Coil 118b Magnet 118c Yoke 119 Flexible substrate 120 Magnet, sensor fixing member 121 Guide shaft 123a Sensor 123b Scale 124 Scale holding member Z Drive mechanism (second drive mechanism)

Claims (4)

A focus lens as a first lens group, and a first lens holding member that holds a coil driven by a flexible substrate;
A second lens holding member that holds the second lens group;
A guide shaft for guiding the first lens holding member in the optical axis direction, a magnet for moving the first lens holding member in the optical axis direction by a magnetic action with the coil, and the first lens holding member A sensor that detects a position in the optical axis direction of the fixed member, and a fixed member that holds the image sensor;
A cylindrical driving mechanism fixed to the fixing member and moving the second lens holding member in the optical axis direction;
Arranging the coil, the magnet, and the sensor in this order along the circumferential direction of the drive mechanism in a region between the first lens holding member and the drive mechanism as viewed from the optical axis direction , A lens driving device , wherein a flexible substrate is arranged on the opposite side of the magnet with respect to the coil .   The lens driving device according to claim 1, wherein a magnet fixing member for fixing the magnet to the fixing member also serves as a sensor fixing member for fixing the sensor.   The lens driving device according to claim 1, wherein the magnet attracts a yoke that guides the magnetic force of the magnet.   The lens driving device according to claim 1, wherein the driving mechanism is a zoom driving mechanism.

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