Imaging module having stabilization mechanism

An imaging module is provided with an image pickup device unit having an image pickup device; an optical unit to form a subject image on the image pickup device; and an image stabilization mechanism having a first drive unit to move an image stabilization object element that is at least one of the image pickup device and the optical unit in a first direction that is parallel with an imaging area of the image pickup device, and a second drive unit to move the image stabilization object element in a second direction that is parallel with the imaging area and intersects with the first direction, wherein the imaging module has a rectangular shape on a plane that is parallel with the imaging area, and the first drive unit and the second drive unit are respectively arranged around the optical unit and at two neighboring sides of the imaging module.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of Japanese Application No. 2010-064176 filed Mar. 19, 2010, the contents of which are incorporated by this reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an imaging module provided with an image stabilization mechanism.

2. Description of the Related Art

Conventionally, mobile phones are provided with cameras, and most of those cameras are fixed focal length cameras. DSCs (Digital Still Cameras) have a high magnification, and in particular require image stabilization. On the other hand, fixed focal length cameras are less susceptible to camera shaking.

However, photographs are typically taken with one hand when a mobile phone camera is used. As a result, the amount of camera shaking is far larger than that of DSCs, with which photographs are taken using both hands. Accordingly, the need for image stabilization for mobile phones is intensifying.

In DSCs in particular, the image stabilization mechanism has a large footprint and a relatively large thickness. On the other hand, in mobile phones or small DSCs in particular, downsizing of the image stabilization mechanism or even downsizing of an imaging module is desired, and various types of image stabilization mechanisms have been proposed (for example, see Patent Documents 1-3: Patent Document 1 (Japanese Laid-open Patent Publication No. 2006-113545); Patent Document 2 (Japanese Laid-open Patent Publication No. 2006-330678); and Patent Document 3 (Japanese Laid-open Patent Publication No. 2006-295553)).

The image stabilization mechanism used for imaging devices includes the image stabilization performed by moving an image pickup device or an optical system in an X-direction and a Y-direction that are parallel with the imaging area.

For example, in the image stabilization mechanism according to Patent Documents 1 and 2, a drive unit for moving an image pickup device as an image stabilization object element is arranged under an optical system.

In particular, in the image stabilization mechanism according to Patent Document 1, the footprint is large, and the above-mentioned drive unit is arranged in a large space around the image pickup device.

In the image stabilization mechanism according to Patent Document 2, the above-mentioned drive unit is arranged further under the image pickup device, and has a great thickness.

SUMMARY OF THE INVENTION

An imaging module according to the present invention is provided with an image pickup device unit having an image pickup device, an optical unit to form a subject image on the image pickup device, and an image stabilization mechanism having a first drive unit to move an image stabilization object element that is at least one of the image pickup device and the optical unit in a first direction that is parallel with an imaging area of the image pickup device, and a second drive unit to move the image stabilization object element in a second direction that is parallel with the imaging area and intersects with the first direction, where the imaging module has a rectangular shape on a plane that is parallel with the imaging area, and the first drive unit and the second drive unit are respectively arranged around the optical unit and to at two neighboring sides of the imaging module.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An imaging module according to an embodiment of the present invention will be described below with reference to the accompanying drawings.FIGS. 1 and 2are exploded perspective views of an imaging module100according to an embodiment of the present invention from the upper left and lower right, respectively.

FIG. 3is an exploded perspective view of an image stabilization mechanism1of the imaging module100from the upper left.

FIG. 4is a plan view of the imaging module100.

FIGS. 7-9are a perspective view of a Y-direction drive unit30of the imaging module100from the back side, and a rear view and a right-side view of the Y-direction drive unit30of the imaging module100, respectively.

FIG. 10is a block diagram explaining the control structure of the imaging module100.

As illustrated inFIGS. 1 and 2, the imaging module100is provided with an image stabilization mechanism1, an image pickup device unit110having an image pickup device111as an image stabilization object element, and an optical unit120that forms a subject image on the image pickup device111. The imaging module100is used, for example, for a mobile phone or a small-sized DSC.

As illustrated inFIG. 3, the image stabilization mechanism1is provided with a Y-direction slider10as a first movable unit, an X-direction drive unit20that is a voice coil motor (VCM) as a first drive unit, a Y-direction drive unit30that is a voice coil motor (VCM) as a second drive unit, hall elements41and42, a control unit51, a gyroscope52as a camera shaking detection sensor, a holder60, an X-direction slider70as a second movable unit, a base unit80, and a top cover91and a bottom cover92that form the cabinet of the image stabilization mechanism1and the imaging module100.

The Y-direction slider10has a rectangular-shaped frame that is open on the top face and bottom face. Moreover, an optical unit120that has a square shape in a planar view, which will be described later, is disposed in the Y-direction slider10, and thus the Y-direction slider10has an approximately square shape in a planar view.

As illustrated inFIGS. 5 and 6, under the Y-direction slider10, the image pickup device unit110is fixed to a cover glass holder114by, for example, adhesion. Note that the position at which the image pickup device unit110is fixed is not limited to the upper surface of the cover glass holder114, but the image pickup device unit110may be fixed to the rim of the cover glass holder114. As described above, the Y-direction slider10is indirectly provided with the image pickup device111, and thus it is possible for the image pickup device111to move with the Y-direction slider10in an integrated manner.

The Y-direction slider10is moved by the Y-direction drive unit30in the Y-direction (i.e., “first direction”, which is parallel with an imaging area111aof the image pickup device111). In particular, the Y-direction slider10is penetrated by a Y-direction guide axis71of the X-direction slider70at a through-hole11as illustrated inFIG. 5, and the Y-direction slider10slides along this Y-direction guide axis71in the Y-direction.

Moreover, the Y-direction slider10is also moved by the X-direction drive unit20in the X-direction (i.e., “second direction”, which is parallel with the imaging area111aof the image pickup device111and that intersects with the above-mentioned first direction) together with the X-direction slider70, as will be described later in detail. In other words, the image pickup device111moves in both the Y-direction and X-direction with the Y-direction slider in an integrated manner.

As illustrated inFIGS. 3 and 5, the X-direction drive unit20is provided with magnets21and22, a coil23, and a yoke24. Moreover, as illustrated inFIG. 3andFIGS. 6-9, the Y-direction drive unit30is provided with magnets31and32, a coil33, and a yoke34in a similar manner as the X-direction drive unit20.

The X-direction drive unit20and the Y-direction drive unit30are arranged around an optical unit120. Moreover, the X-direction drive unit20and the Y-direction drive unit30are respectively arranged at two neighboring sides of a plane of the imaging module100, which is parallel with the imaging area111aand has a rectangle shape.

As illustrated inFIGS. 3 and 5, the magnets21and22of the X-direction drive unit20are long in the Y-direction, and are opposite to the coil23in the height direction (i.e., the optical-axis direction of the optical unit120), which intersects with the imaging area111aof the image pickup device111. Furthermore, the magnets21and22are opposite to each other across the coil23in the height direction.

In a similar manner, as illustrated inFIG. 4andFIGS. 6-9, the magnets31and32of the Y-direction drive unit30are long in the X-direction, and are opposite to the coil33in the height direction, which intersects with the imaging area111aof the image pickup device111. Furthermore, the magnets31and32are opposite to each other across the coil33in the height direction.

The yoke24of the X-direction drive unit20surrounds the magnets21and22as well as the coil23, and has a quadrangular-shaped section that is open on the side of the optical unit120. In a similar manner, the yoke34of the Y-direction drive unit30surrounds the magnets31and32as well as the coil33, and has a quadrangular-shaped section that is open on the side of the optical unit120. The yokes24and34are formed, for example, by bending a metal plate.

The shape of the sections of the yokes24and34is not limited to a quadrangular shape in which one side is open, but may have, for example, an L-shaped section that is open on the top face or the bottom face in addition to the side of the optical unit120, or an I-shaped section that is open on the side of the optical unit120as well as the top face and the bottom face. In other words, the yokes24and34may be composed of a plate that is positioned on the opposite side of the optical unit120.

The coils23and33are fixed to the outer surface of the Y-direction slider10. As illustrated inFIG. 5, the magnets21and22and the yoke24of the X-direction drive unit20are fixed to the top face of the base unit80at the bottom face of the yoke24. On the other hand, as illustrated inFIG. 6, the magnets31and32and the yoke34of the Y-direction drive unit30are fixed to a concave portion62that is formed on the top face of a holder60at the bottom face of the yoke24. Note that the X-direction drive unit20and Y-direction drive unit30may be fixed to an inner surface of a bottom cover92.

The magnets21and31positioned above the X-direction drive unit20and Y-direction drive unit30are longer than the magnets22and32positioned below, and have protruding portions21aand31athat protrude from the portion surrounded by the yoke24. Note that it is not always necessary for the magnets21and31to protrude from the yoke24, but the magnets21and31may be surrounded by the yoke24.

Under the protruding portions21aand31a, hall elements41and42are arranged so as to be opposite to these protruding portions21aand31a. As will be described later in detail, the hall elements41and42detect the magnetic field intensity and thereby detect the amount of movement of the image pickup device111in the X-direction and the Y-direction. Note that the hall elements41and42are fixed to an outer surface of the Y-direction slider10.

As illustrated inFIG. 5, a flexible substrate115of the image pickup device unit110is dragged into the space around the optical unit120opposite to the X-direction drive unit20across the optical unit120. The flexible substrate115is connected to, for example, a control unit51.

As illustrated inFIG. 6, a control unit51and a gyroscope52are arranged around the optical unit120and are arranged so as to be opposite to the Y-direction drive unit30across the optical unit120. Note that the control unit51and the gyroscope52are arranged on, for example, the same substrate held between the top cover91and the holder60. The control of the X-direction drive unit20, the Y-direction drive unit30, or the like by the control unit51will be described later in detail.

As illustrated inFIGS. 5 and 6, the optical unit120is fixed to the top face of the holder60by, for example, adhesion. The holder60is fixed to the top surface of the base unit80at, for example, its bottom face. Note that the holder60has an approximately rectangular shape in a planar view, and has a through-hole61formed in the height direction. This through-hole61is formed in a circular shape in a planar view in a similar manner as the lens (optical element)121of the optical unit120. A light beam that passes through the lens121goes through this through-hole61, but it is not always necessary for the through-hole61to have a circular shape. Alternatively, the through-hole61may have a rectangular shape or a shape in which a circular shape and a rectangular shape are combined.

As illustrated inFIG. 3, the X-direction slider70has a rectangular-shaped frame that is open on the top face and the bottom face. Guide supporting units72aand72bthat support the above-mentioned Y-direction guide axis71are provided for the X-direction slider70. Note that the Y-direction guide axis71is arranged around the image pickup device unit110.

The magnets21and22and the coil23of the X-direction drive unit20move X-direction slider70together with the Y-direction slider10in the X-direction with reference to the base unit80. In particular, as illustrated inFIG. 6, the X-direction slider70has a through-hole73that an X-direction guide axis81of the base unit80penetrates. Further, the X-direction slider70slides into the through-hole73along the X-direction guide axis81in the X-direction.

Note that due to the configuration in which the X-direction slider70has a rectangular-shaped frame, the intensity of the X-direction slider70for movement in the Y-direction and X-direction can be secured even if the X-direction slider70is provided with not only the Y-direction guide axis71but also the through-hole73that the X-direction guide axis81penetrates.

The base unit80is provided with the above-mentioned X-direction guide axis81and a guide supporting unit82on which through-holes82aand82bare formed. Note that the X-direction guide axis81is fit to and inserted into the through-holes82aand82b. The X-direction guide axis81is also arranged around the image pickup device unit110, in a similar manner as the Y-direction guide axis71.

As illustrated inFIGS. 1-3, the bottom cover92has a rectangular parallelepiped box shape, and is open on the top face. As illustrated inFIGS. 5 and 6, the top cover91is arranged so as to fit into, for example, the top end of the inner surface of the bottom cover92.

As illustrated inFIGS. 5 and 6, the image pickup device unit110is provided with the image pickup device111, a base substrate112on which this image pickup device111is mounted, a cover glass113as a light transmissive cover, a cover glass holder114that holds this cover glass113, and the above-mentioned flexible substrate115.

The optical unit120is provided with a lens121that forms a subject image on the image pickup device111, and an autofocus actuator (not illustrated) such as a voice coil motor that holds the lens121by sandwiching the lens121with an elastic body. Note that the optical unit120has a square shape in a planar view in a similar manner as the imaging module100, and the center position in a planar view is the same as the center position of the imaging module100. Furthermore, the optical axis of the lens121also coincides with the center position of the imaging module100.

The image pickup device unit110and the optical unit120are respectively fixed to the image stabilization mechanism1from the opposite sides in the height direction (i.e., the direction intersecting with the imaging area111a). More specifically, the image pickup device unit110is fixed to the bottom face of the Y-direction slider10, and the optical unit120is fixed to the top face of the holder60. Note that the position to which the image pickup device unit110is fixed is not limited to the bottom face of the Y-direction slider10. The position to which the optical unit120is fixed is also not limited to the top face of the holder60.

As illustrated inFIG. 10, the above-mentioned control unit51detects the amount of camera shaking (angular velocity) of an imaging device (not illustrated) by an X-direction detection unit52aand a Y-direction detection unit52bof the gyroscope52. The control unit51calculates the detected amount of camera shaking as the amount of movement of the image pickup device111, and feeds electric current to the coils23and33of the X-direction drive unit20and Y-direction drive unit30according to the amount of movement. Accordingly, the Y-direction slider10moves along the Y-direction guide axis71in the Y-direction, and the Y-direction slider10and the X-direction slider70move along the X-direction guide axis81in the X-direction, as described above. Accordingly, the image pickup device111of the image pickup device unit110provided to the Y-direction slider10moves in the Y-direction and the X-direction.

The hall elements41and42are arranged so as to be opposite to the protruding portions21aand31aof the magnets21and31as described above, and the hall elements41and42detect the amount of movement of the image pickup device111in the X-direction and the Y-direction by detecting the magnetic field intensity.

As long as the amount of movement of the image pickup device111detected by the hall elements41and42does not match the calculated amount of movement, the control unit51repeats the operation of feeding electric current to the coils23and33of the X-direction drive unit20and Y-direction drive unit30to move the image pickup device111and the operation of detecting the amount of movement of the image pickup device111using the hall elements41and42.

Note that the X-direction drive unit (first drive unit)20and the Y-direction drive unit (second drive unit)30are not limited to the magnetism generating units (voice coil motors) that use magnets21,22,31, and32and coils23and33, and may be piezoelectric elements or other types of drive units. Nevertheless, it is still desirable to use magnetism generating units.

In the above-described present embodiment, the X-direction drive unit20and the Y-direction drive unit30are respectively arranged around the optical unit120and are respectively arranged at two neighboring sides of the imaging module100. That is, according to the present embodiment, downsizing is achieved of the imaging module100with which the image stabilization mechanism1is provided and which moves the image stabilization object element (image pickup device111) in two directions (Y-direction and X-direction) that are parallel with the imaging area111aand intersect with each other.

Moreover, in the present embodiment, both (or at least one of) the gyroscope52and the control unit51are arranged around the optical unit120and are arranged so as to be opposite to the Y-direction drive unit30across the optical unit120. Accordingly, even if the center of the imaging module100in a planar view is matched with or is close to the optical axis of the lens121, downsizing of the imaging module100may be achieved by utilizing the space within the imaging module100.

Moreover, in the present embodiment, the flexible substrate115of the image pickup device unit110is dragged in the space around the optical unit120opposite to the X-direction drive unit20across the optical unit120. Accordingly, even if the center of the imaging module100is matched with or is close to the optical axis of the lens121, downsizing of the imaging module100may be achieved by utilizing the space within the imaging module100.

Moreover, in the present embodiment, both (or at least one of) the X-direction drive unit20and the Y-direction drive unit30include the coils23and33as well as the magnets21,22,31, and32opposite to the coils23and33in the direction intersecting with the imaging area111a. Accordingly, downsizing of the imaging module100may be achieved by minimizing the space around the optical unit120.

Further, in the present embodiment, both (or at least one of) the X-direction drive unit20and the Y-direction drive unit30include the coils23and33as well as the two or more magnets21,22,31, and32that are opposite to each other across the coils23and33in the direction intersecting with the imaging area111a. Accordingly, the imaging module100may be further downsized.

Further, in the present embodiment, both (or at least one of) the X-direction drive unit20and the Y-direction drive unit30include the coils23and33, the two or more magnets21,22,31, and32, and the yokes24and34with quadrangular-shaped sections that are open on the side of the optical unit120. Accordingly, the driving force may be strengthened with a simple configuration.

Moreover, in the present embodiment, both (or at least one of) the Y-direction guide axis71and the X-direction guide axis81are arranged around the image pickup device unit110. Accordingly, the imaging module100may be further downsized by reducing the footprint of the imaging module100.

Moreover, in the present embodiment, the optical unit120and the image pickup device unit110are fixed to the image stabilization mechanism1from opposite sides in the direction intersecting with the imaging area111a. Accordingly, the assembly of the imaging module100becomes easy.

Moreover, in the present embodiment, the X-direction drive unit20and the Y-direction drive unit30move the image pickup device111as an image stabilization object element in the X-direction and the Y-direction. Accordingly, image stabilization may be performed without causing defocusing. Such defocusing is caused, for example, when the optical unit120is moved.

In the present embodiment, cases in which the coils23and33are arranged beside the Y-direction slider10and the magnets21,22,31, and32are arranged beside the fixed base unit80or holder60have been described. However, it is still a possible configuration for the coils to be arranged beside the fixed sides and the magnets to be arranged beside the movable sides.

FIG. 11illustrates a section view of the imaging module200(corresponding to a section view of V-V ofFIG. 4, as illustrated inFIG. 5) according to the first variation of the present embodiment. In the imaging module200according to the present variation, the optical unit120is an image stabilization object element instead of the image pickup device111.

The imaging module200according to the present variation is different from the above-described imaging module100as the optical unit120is fixed to the Y-direction slider210and the image pickup device unit110is fixed to the holder260.

Accordingly, the Y-direction slider210moves along the Y-direction guide axis71of the X-direction slider70in the Y-direction in a through-hole211, and the X-direction slider70moves along the X-direction guide axis81of the base unit80(not illustrated inFIG. 11) in the X-direction. As a result of that, the optical unit120moves in the X-direction and the Y-direction.

As described above, in the present variation, the X-direction drive unit20and Y-direction drive unit30move the optical unit120as an image stabilization object element in the X-direction and the Y-direction, which are parallel with the imaging area111aof the image pickup device111and which intersect with each other. Accordingly, compared with the case in which the optical unit120rotates on, for example, a plane that is parallel with the imaging area111a, defocusing (image blur) can be better prevented in the present variation by preventing instability in a lens121due to the vibration of an elastic body even if an autofocus actuator (voice coil motor) (not illustrated) sandwiches the lens121with an elastic body.

FIGS. 12A and 12Bare section views of an imaging module300according to the second variation of the present embodiment (corresponding to section views of V-V and VI-VI ofFIG. 4, as illustrated inFIGS. 5 and 6). The imaging module300according to the present variation is provided with the X-direction drive unit20and the Y-direction drive unit30respectively arranged at two neighboring sides of the imaging module300, and an X-direction drive unit320and a Y-direction drive unit330that are arranged so as to be opposite to the X-direction drive unit20and the Y-direction drive unit30.

The X-direction drive unit320and the Y-direction drive unit330are provided with magnets321,322,331, and332, coils323and333, and yokes324and334in a similar manner as the X-direction drive unit20and Y-direction drive unit30.

In the present variation, it is desirable that the above-described control unit51, gyroscope52, and flexible substrate115be arranged outside the top cover91and the bottom cover92, or, although not illustrated, it is desirable that the magnets and coils of the X-direction drive unit320and the Y-direction drive unit330be reduced in size in the dimensions corresponding to the diameter and height of lens and be arranged together with the control unit51, the gyroscope52, and the flexible substrate115.

According to the present variation, the driving force can be enhanced due to the X-direction drive unit20and the X-direction drive unit320, which are opposite to each other, and due to the Y-direction drive unit30and the Y-direction drive unit330, which are also opposite to each other.

FIG. 13is a section view of an imaging module400according to the third variation of the present embodiment (corresponding to a section view of V-V ofFIG. 4, as illustrated inFIG. 5).

The imaging module400of the present variation is a combination of the cover glass holder (114) of the above-described embodiment in which a Y-direction slider410holds the cover glass113as a light transmissive cover, and the Y-direction slider (10) of the above-described embodiment. According to the present variation, simplification of the imaging module400can be achieved.

In the accompanying drawings, sections or the like are illustrated with hatching, but the material of each part is not limited by the type of hatching. For example, plastic is used for the Y-direction slider10, the holder60, the X-direction slider70, the base unit80or the like; however, different material may be used for those parts. Likewise, metal is used for the Y-direction guide axis71, the X-direction guide axis81, the top cover91, the bottom cover92or the like; however, different material may be used for those parts.