Abstract:
A compact and power saving imaging-element unit of handshake compensation type is provided. The imaging-element unit comprises an imaging-element board with an imaging element that performs photoelectric conversion of incident light formed or located thereon; a relay board that is disposed between the imaging element and an external control board, and that receives signals between the imaging-element board and the external control board; and a package with at least the imaging-element board and the relay board contained therein; wherein a slider mechanism is disposed between the imaging-element board and the relay board for moving the imaging-element board to compensate handshake of an imaging device.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an imaging device, and more particularly to an imaging-element unit that is capable of compensating handshake of the imaging device when taking images. 
   2. Description of the Prior Art 
   Currently, active handshake compensation technology that makes it possible to obtain clear and sharp images has been put into practical use. This shakiness-compensation technology are basically classified into three types: a type of moving a part of an imaging optical system; another type of moving the entire imaging optical system; and a further type of moving an imaging element. 
   A technique has been disclosed, for example, in Japanese patent Publication No. 2006-133740 as the type of moving the imaging element in which the imaging element is mounted on a board inside a housing by way of balls, and shakiness is compensated for by moving the board inside the housing. 
   However, the handshake compensation device disclosed in Japanese patent Publication No. 2006-133740 uses a flexible printed circuit board for exchanging signals between the imaging element and the outside control board. Therefore, when moving the imaging element in the imaging plane in order to compensate handshake, the flexible printed circuit board must also be moved. 
   In order to move the imaging element in the imaging plane against the repulsion force that occurs due to the flexure of the flexible printed circuit board, a large driving force is needed, which becomes an obstacle to compactness and saving of electric power of the imaging device. 
   SUMMARY OF THE INVENTION 
   Taking the aforementioned problems into consideration, it is an object of the present invention to obtain an imaging-element unit of compact and power saving type, and that is capable of compensating handshake, and to obtain an imaging device that is compact, has low power consumption and is capable of compensating handshake. 
   The object of the invention is accomplished as described below. 
   A first aspect of the invention is an imaging-element unit comprising: 
   an imaging-element board with an imaging element that performs photoelectric conversion of incident light formed or mounted thereon; 
   a relay board disposed between the imaging element and an external control board for receiving and transmitting signals between the imaging-element board and the external control board; and 
   a package encompassing at least the imaging-element board and the relay board, 
   wherein a slider mechanism is disposed between the imaging-element board and the relay board for moving the imaging-element board in a plane perpendicular to an optical axis of the imaging element unit. 
   A second aspect of the invention is the imaging-element unit of the first aspect described above wherein drive power is supplied to the imaging element by way of an electrical contact section of the slider mechanism. 
   A third aspect of the invention is the imaging-element unit of the first or second aspect described above wherein reception and transmission of signals between the imaging-element board and the relay board is performed in no contact way. 
   A fourth aspect of the invention is the imaging-element unit of any one of the aspects 1 to 3 described above wherein at least one of driving coils for moving the imaging-element board and a position detection sensor for detecting a position of the imaging-element board is arranged on the imaging-element board. 
   A fifth aspect of the invention is the imaging-element unit of any one of the aspects 1 to 3 described above wherein a driving coil for moving the imaging-element board is arranged on the slider mechanism. 
   A sixth aspect of the invention is the imaging-element unit of the fourth or fifth aspect described above wherein a magnet is arranged outside of the package opposing the driving coils. 
   A seventh aspect of the invention is the imaging-element unit of the fourth or fifth aspect described above wherein a magnet is arranged inside of the package opposing the driving coils. 
   An eighth aspect of the invention is that an imaging device comprises the imaging-element unit of any one of the first to seventh aspects described above, and an imaging optical system for directing a light from an object to the imaging-element unit, wherein said imaging device compensates handshake by moving said imaging-element board in a plane perpendicular to an optical axis of the imaging optical system. 
   With the present invention, a compact and power saving imaging-element unit that is capable of compensating handshake, and a compact and low power consuming imaging device that is capable of correcting for shakiness are provided. 
   The above and many other objects, features and advantages of the present invention will become manifest to those skilled in the art upon making reference to the following detailed description and accompanying drawings in which preferred embodiments incorporating the principle of the present invention are shown by way of illustrative examples. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1A  is a perspective view illustrating a front side of a camera as an example of an imaging device in which an imaging-element unit according to an embodiment of the present invention is mounted and  FIG. 1B  is also a perspective view illustrating a back side of the camera shown in  FIG. 1A ; 
       FIG. 2  is a cross-sectional view of a lens barrel of an imaging device with the imaging-element unit of the present invention mounted; 
       FIG. 3  is a cross-sectional view of the imaging-element unit of the embodiment of the present invention; 
       FIG. 4  is a plan view of a relay board of the attachment unit mounted on the bottom of the image-element unit; 
       FIG. 5A  shows an example of ball receiving member and 
       FIG. 5B  show another example of a ball receiving member; 
       FIG. 6A  is a top view of one surface of a first slider opposing the attachment unit and  FIG. 6B  is a top view of the other surface of the first slider opposing another slider; 
       FIG. 7A  is a top view of one surface of a second slider opposing the first slider and  FIG. 7B  is a top view of the other surface of the second slider attached onto an imaging-element board; 
       FIG. 8A  is a top view of one surface of the imaging-element board to which the second slider is attached and  FIG. 8B  is a top view of another surface of the imaging element board; 
       FIG. 9  is a sectional view of the imaging element unit taken along the line H-H in  FIG. 3 ; 
       FIG. 10  is a sectional view of the imaging element unit taken along the line I-I in  FIG. 3 ; 
       FIG. 11  is a sectional view of the imaging element unit taken along the line J-J in  FIG. 3 ; 
       FIG. 12  shows a block diagram of the shakiness-compensation control circuit; 
       FIG. 13  is a plan view of the attachment unit of another embodiment of the relay board of the present invention which is similar to  FIG. 4  and 
       FIG. 14  is a sectional view of the embodiment shown in  FIG. 13  which is similar to  FIG. 9 . 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The invention will now be explained in detail below with respect to the preferred embodiments, however, the invention is not limited to these embodiments. 
     FIGS. 1A and 1B  illustrate a camera as an example of an imaging device in which the imaging-element unit of an embodiment of the present invention is mounted wherein  FIG. 1A  is a perspective view of the front side of the camera, and  FIG. 1B  is a perspective view of the back side of the camera. 
   Referring to  FIG. 1A , the camera includes a lens barrel  80 , a finder window  82 , a release button  83 , a flash unit  84 , a microphone  86 , a strap attachment unit  87 , a USB terminal  88  and a sliding cover  89 . The lens barrel  80  retracts inside, when not taking images. 
   Referring to  FIG. 1B , the camera has a finder lens section  91  and red and green display lamps  92  that display AF or AE information for a user by lighting up or flashing when the release button  83  is pressed. A zoom button  93  is provided for zooming in or zooming out. A speaker  94  is adapted to reproduce a sound recorded by the microphone  86 , a releasing sound and so on. There are provided a menu/set button  95 , a selection button  96  with four-way switch, and a LCD monitor  100  adapted to display the image and other character information. A delete button  99  is provided for deleting images that have been recorded. A tripod screw hole  101  and a battery/card lid  102  are also provided. A battery that supplies power to the camera, and a card-type removable memory in which taken images are recorded are loaded inside of the battery/card lid  102 . 
     FIG. 2  is a longitudinal cross-sectional view of the lens barrel  80  of the imaging device taking a wide photographing position with the imaging-element unit  5  mounted. 
   Referring to  FIG. 2 , an imaging optical system comprises three lens groups including a first lens group  1 , a second lens group  2  and a third lens group  3 . For zooming operation, the first lens group  1  and the second lens group  2  are moved in the direction of the optical axis, and for focusing operation, the third lens group  3  is moved in the direction of the optical axis. An optical filter  4  is composed of lamination of an infrared-cut filter and an OLPF (optical low pass filter). The imaging-element unit  5  encompasses an imaging element which is adapted to photoelectrically convert focused light of an object and may be an image sensor such as, for example CCD (Charge Coupled Device) or CMOS (Complementary Metal-oxide Semiconductor). 
   The first lens group  1  is held by a first lens frame  6 , the second lens group  2  is held by a second lens frame  7  and the third lens group  3  is held by a third lens frame  8 . 
   An attachment cylinder  11  is attached integrally with the camera body (not shown) and has a cam groove  11   a  formed on its inner surface. A bottom board  12  is attached to the rear side of the attachment cylinder  11 . The optical filter  4  and imaging-element unit  5  are mounted on the bottom board  12 . The imaging-element unit  5  is electrically connected to a flexible printed circuit board  13 . 
   A cam cylinder  14  has a cam pin  14   a  that fits in the cam groove  11   a  on the attachment cylinder  11 , and has a partial gear  14   b  formed on a part of the rear section. A cam groove  14   c  is formed on the inner surface of the cam cylinder  14 . 
   A front cylinder  15  holds the first lens frame  6  and has three metal cam pins  16  formed on the outer surface thereof. These cam pins  16  engage with the cam groove  14   c  of the cam cylinder  14 . 
   There are also cam pins (not shown) formed on the second lens frame  7  which engage with another cam grooves that are different from the cam groove  14   c  of the cam cylinder  14 . 
   A linear movement member  17  and a linear guide plate  18  are attached to the cam cylinder  14  so that they can rotate and move in the optical-axis direction of the cam cylinder  14 . The linear guide plate  18  engages with a linear guide section  11   m  that is formed on the attachment cylinder  11  as shown, and pivotably supports a drive gear  21  that engages with the partial gear  14   b . The drive gear  21  also engages with a long gear  22  which is driven by a motor and step-down gear train that are not shown in  FIG. 2 . 
   As shown in  FIG. 2 , the linear guide plate  18  makes direct contact with the ring-shaped surface on the imaging-element unit  5  of the cam cylinder  14 , and slides while the linear movement member  17  makes direct contact with the inside surface of the cam cylinder  14  and slides. A linear guidance section  17   t  is formed on the linear movement member  17 , and engages with the front cylinder  15  and the second lens frame  7  which are designed to guide the front cylinder  15  and the second lens frame  7  linearly. A diaphragm shutter unit  33  is attached to the second lens frame  7 . It is also possible that the front cylinder  15  may be moved by the linear guide plate  17   t  linearly so that the second lens frame  7  is engaged with the linearly moving front cylinder  15  so as to be linearly guided. 
   A focusing motor  41  has a feed screw  42  onto which a nut  43 , whose rotation is regulated, is screwed. The third lens frame  8  has its arm pressed against the nut  43  by a spring  44 . With this arrangement, rotation of the focusing motor  41  causes the feed screw  42  to rotate, so that the nut  43  moves in the direction of the optical axis O, with the result that the third lens frame  8  is moved in the direction of the optical axis O to perform focusing and retraction of the third lens group  3 . 
   With such construction, when another motor (not shown) is driven to rotate in a given direction, the cam cylinder  14  is rotated by the long gear  22  and the drive gear  21 . As a result, the front cylinder  15  with the cam pins  16  in engagement with the cam groove  14   c  formed on the inner periphery of the cam cylinder  14 , and the second lens frame  7  in engagement with the cam groove (not shown in the figure) formed on the cam cylinder  14  are linearly guided by the linear guide unit  17   t  and moved in the direction of the optical axis O to perform the zooming operation. In this way, the wide position shown in  FIG. 2  is shifted to the telescopic position. 
   On the other hand, when it is expected to shift the wide position shown in  FIG. 2  to the retracted position, the focusing motor  41  is first driven to move the third lens frame  8  toward the imaging-element unit  5 , and after that another motor (not shown in the figure) is driven to in the opposite direction so that the long gear  22  and the drive gear  21  cause the cam cylinder  14  to rotate in the opposite direction. As a result, the cam cylinder  14  is guided by the cam groove  11   a  formed on the attachment cylinder  11  to move toward the imaging-element unit  5  and the front cylinder  15  with the cam pins  16  in engagement with the cam groove  14   c  formed on the inner periphery of the cam cylinder  14 , and the second lens frame  7  in engagement with the cam groove (not shown in the figure) formed on the cam cylinder  14  are linearly guided by the linear guide unit  17   t  and moved in the direction of the imaging-element unit  5  to the retracted position as shown in the figure. At this time, the linear movement member  17  and the linear guide plate  18  move linearly together with the cam cylinder  14 . 
   The construction and operation of the lens barrel  80  has been described above. Next, the imaging-element unit  5  of this embodiment will be explained in detail. 
     FIG. 3  is a cross-sectional view of the imaging-element unit  5  of the embodiment of the present invention and particularly illustrates its internal structure. 
   The imaging-element unit  5  has a package  51 , a relay board  52  that is connected to the flexible printed circuit board  13  as shown in  FIG. 2  for connecting to an external control board, and a cover glass plate  53 . 
   An imaging element  54  comprises light receiving elements arranged in a two-dimensional array formed on an imaging-element board  55 . In this embodiment, the imaging element  54  and imaging-element board  55  are formed of the same silicon chip. The imaging-element board  55  and the relay board  52  are electrically connected by wire bonding  59 . 
   A slider mechanism  60  is arranged between the imaging-element board  55  and the relay board  52  to enable surface displacement in X and Y directions that is orthogonal to the optical axis O. The slider mechanism  60  comprises a first slider  57  arranged by way of balls on an attachment unit  56  that is fixedly mounted on the relay board  52  and a second slider  58  arranged by way of balls on the first slider  57 . The imaging-element board  55  is fixedly mounted on the second slider  58 . The imaging-element board  55  is adapted to move in two perpendicular directions (X and Y directions within a planes orthogonal to the optical axis O by movement of the slider  57  and the second slider  58 . 
   Moreover, magnets  65  and  66  are arranged on the back surface of the cover glass  53 . These magnets may be arranged on the front surface of the cover glass  53  as shown in  FIG. 3  by a double chain line. 
     FIG. 4  is a plan view of the relay board  52 . 
   Referring to  FIG. 4 , there are two lands  56   a  and  56   b  integrally formed on the upper surface of the relay board  52 . On the land  56   a  are formed two V-shaped grooves VG 1  and VG 2  whose bottom is V-shaped in section and on the land  56   b  is formed a single groove FG 1  whose bottom is flat. The V-shaped grooves VG 1  and VG 2  are exactly the same and therefore the V-shaped groove VG 1  as an example and the groove FG 1  are illustrated in  FIG. 5A  and  FIG. 5B , respectively. Balls  111 ,  112  and  113  which are arranged in the V-shaped grooves VG 1  and VG 2  and the groove FG 1 , respectively are made of metallic material or has a coating of electrically conductive material on their surfaces. There are electrically conductive patterns formed on the portion of the surface and the bottom of the V-shaped groove VG 1  and VG 2  and the groove FG 1  with which the balls  111 ,  112 ,  113 , are in physical and electrical contact. The conductive patterns formed on these grooves VG 1  and FG 1  are shown by a dotted area in  FIGS. 5A and 5B . On the relay board  52  are also mounted a handshake compensation control integrated circuit  120  and an imaging element controller  126 . Along one side and opposite side of the relay board  52  are provided a plurality of soldering lands  56   c  and  56   d  shown by hatched lines for connection to outside circuits not shown. A plurality of lead frames  56   e   1  and  56   e   2  extend from the relay board  52  wherein an electric power Vp is supplied through one of the lead frames  56   e   1  and control signals are led through the lead frames  56   e   2 . More specifically, power-supply Vp for the relay board  52 , power supply Vd for digital circuits and ground line G are connected to the balls  111 ,  112  and  113  through the conductive patterns formed on the ball receiving members from lead frames  56   e   1 . Control signals to and from the imaging elements controller  126  are lead through the lead frames  56   e   2 . 
   Slider mechanism  60  will be described in detail with reference to  FIGS. 6A ,  6 B and  FIGS. 7A ,  7 B. 
     FIGS. 6A and 6B  show respective surfaces of the first slider  57 . More specifically,  FIG. 6A  shows the surface of the first slider  57  opposing the relay board  52  and  FIG. 6B  shows the surface of the slider  57  opposing the second slider  58 . 
   As shown in  FIG. 6A , there are two V-shaped grooves VG 3  and VG 4  and a groove FG 2  formed on the surfaces of the first slider  57  in which the balls  111 ,  112  and  113  are placed, respectively. 
   When the first slider  57  is place in position in parallel to the relay board  52 , the V-shaped grooves VG 3  and VG 4  oppose the V-shaped grooves VG 1  and VG 2  on the relay board  52 , respectively. The groove FG 2  on the first slider  57  also oppose the groove FG 1  on the relay board  52 . The V-shaped grooves VG 3  and VG 4  and the groove FG 2  are of the same structure as the V-shaped grooves VG 1  and VG 2  and the groove FG 1  shown in  FIGS. 5A and 5B , respectively. On the centre of the surface of the first slider  57  is also arranged an yaw-direction driver circuit  125 . With this structure, the power-supply Vp, the power-supply Vd for digital circuits and the ground line G are connected to the first slider  57  through the balls  111 ,  112  and  113  and the relay board  52 . 
   On the opposite surface of the first slider  57 , there are three grooves formed as shown in  FIG. 6B . The grooves VG 5  and VG 6  are V-shaped grooves as shown in  FIG. 5A  and the groove FG 3  is the groove shown in  FIG. 5B . A set of balls  114 ,  115  and  116  are placed in the V-shaped grooves VG 5  and VG 6  and the groove FG 3 , respectively. There is also a Y coil  124  for generation of an electromagnetic force by cooperation with a magnet  66  arranged on the cover glass plate  53  for driving the imaging-element board  55  in the yaw direction which is formed on the same surface of the first slider  57 . 
   As a result, the power-supply Vp, the power-supply Vd for the digital circuits and the ground line G are connected to the surface of the first slider  57  opposing the second slider B  58  by way of through holes as shown in  FIG. 6B . The power-supply Vp is connected to the ball  114 , the power supply for the digital circuits Vd is connected to the ball  115  and the ground line G is connected to the ball  116  through the conductive patterns formed at the positions connecting to the through holes. 
     FIG. 7A  shows the surface of the second slider  58  opposing the first slider  57  and  FIG. 7B  shows the surface of the second slider  58  which is attached to the imaging-element board  55 . 
   As shown in  FIG. 7A , there are two V-shaped grooves VG 7  and VG  8  and a groove FG 4 . These grooves VG 7 , VG 8  and the groove FG 4  are those shown in  FIGS. 5A and 5B . In  FIG. 7B , only through halls  204 ,  205  and  206  can be viewed. 
     FIGS. 8A and 8B  show the respective surfaces of the imaging-element board  55 . 
   On the surface of the imaging-element board  55  shown in  FIG. 8A  to which the second slider  58  is attached, a P coil  123  for generation of an electromagnetic force by cooperation with the magnet  66  arranged on the cover glass plate  53  for driving the imaging-element board  55  in the pitch direction and an imaging-element controller  127  are provided. The P coil  123  is positioned to cooperate with the magnet  66  disposed on the rear side of the cover glass plate  53 . 
   On the opposite surface of the second slider  58  as shown in  FIG. 8B  are provided the imaging element  54 , a pitch-direction driver circuit  122  for driving the P coil  123  and a two-axis Hall element sensor  121  which functions as a position detection sensor. The two-axis Hall element sensor  121  is positioned to oppose a magnet  65  disposed on the rear side of the cover glass plate  53 . Along the opposite sides of the imaging-element board  55  are provided a plurality of soldering lands  55   c  for wire bonding as shown by hatched lines. 
     FIGS. 9 ,  10  and  11  are sectional views taken along the lines H-H, I-I and J-J in  FIG. 3 , that are presented for easy understanding of the inside structure of the slider mechanism  60 . 
     FIG. 12  shows a block diagram of the connection for power supply to the handshake compensation control circuit. 
   The power-supply Vp is supplied to the pitch-direction driver circuit  122  and the yaw-direction driver circuit  125 , and the power-supply Vd for digital circuits is supplied to the handshake compensation control IC  120  mounted on the relay board  52  and the two-axis Hall element sensor  121 . The ground line G is connected to all of the driver circuits  122  and  125 , the control IC  120  and the two-axis Hall element sensor  121 . 
   An operation of handshake compensation for the imaging-element unit  5  will now be explained. 
   A camera to which the present invention is applied has a sensor (not shown in the figure) that detects shakiness of the camera in the pitch direction (Y direction), and another sensor (not shown in the figure) that detects shakiness of the camera in the yaw direction (X direction). Based on the outputs of these sensors in two directions, the handshake compensation control IC  120  controls the pitch-direction driver circuit  122  and the yaw-direction driver circuit  125 , so that current flows in the P coil  123  and the Y coil  124 . This results in planar movement of the imaging-element board  55 . The amount of planar movement of the imaging-element board  55  is detected by the two-axis Hall element sensor  121 , and feedback is provided to the current flowing in the P coil  123  and the Y coil  124 . Thus, the shakiness correction operation is effected by such feedback control of the movement of the imaging-element board  55 . 
   It is preferred in the embodiment described above that the driving power be supplied to the imaging-element unit  5  by way of the control portion of the slider mechanism  60 . This results in reduction of driving load in comparison with a conventional imaging device in which driving power is supplied to the imaging-element unit by way of a connecting wire, so that the slider mechanism  60  can move with a small driving force, and compactness of the unit and power saving are realized. 
     FIG. 13  is a plan view of the attachment unit of another embodiment of the relay board of the present invention which is similar to  FIG. 4 .  FIG. 14  is a cross sectional view of the attachment unit taken along a line H′-H′ of  FIG. 13  which is similar to  FIG. 9 . In these figures, the same reference numbers will be assigned to parts that are identical to those of the imaging-element unit  5  of  FIG. 4 , in order to avoid redundancy in the explanation. 
   Referring to  FIGS. 13 and 14 , a light-emitting element  71  such as for example a light-emitting diode is arranged on the imaging-element board  55 , and a light-receiving element  72  such as for example, a photodiode is arranged in the corresponding position on the relay board  52 . A light-emitting element  73  is arranged on a different position on the relay board  52  while a light-receiving element  74  is arranged in the corresponding position on the imaging-element board  55 . 
   A control signal from the external control board is transmitted to the imaging-element board  55  by a pair of the light-emitting element  73  and the light-receiving element  74 . An image signal that is obtained by the imaging element  54  is transmitted to the relay board  52  by a pair of the light-emitting element  71  and the light-receiving element  72 , and then is transmitted outside the imaging-element unit  5 . In other words, reception and transmission of a signals between the imaging-element board  55  and the relay board  52  are performed by non-contact type optical communication. 
   Reception and transmission of signals between the imaging-element board  55  and relay board  52  are not limited to optical communication, but may be realized by electromagnetic waves. 
   As explained above, it becomes possible to obtain a compact and power saving imaging-element unit that comprises an imaging-element board, a relay board and a package encompassing at least the imaging-element board and the relay board, by providing a slider mechanism between the imaging-element board and the relay board for moving the imaging-element board, whereby only the lightweight imaging-element board is moved for compensating handshake and displacement is possible with a small driving force. Furthermore, it becomes possible to obtain a compact and power saving function by providing such imaging-element unit. 
   In the embodiments described above, the imaging element  54  and the imaging-element board  55  are formed from the same silicon chip. However, the invention is not limited to this embodiment but the imaging-element board  55  may be integrally formed from a normal printed circuit board, and the imaging element  54 , two-axis Hall element sensor  121  and the driving coil  122  may be formed on that board. A plurality of balls may be arranged in a single V-shaped groove VG and groove FG. 
   It is possible to arrange one of the two-axis Hall element sensor  121  and the driving coil  121  on the imaging-element board  55 , and to arrange the other on the seconder slider  58  of the slider mechanism  60 . 
   Moreover, in the embodiment described above, an optical filter  4  is arranged as a separate member in front of the cover glass  53 , however, the cover glass  53  may function as an OLPF as well. 
   Furthermore, in the embodiment described above, a normal camera was explained as an example of the imaging device. However, it is needless to say that the imaging-element unit  5  with shakiness correction function of the invention can be applied to an imaging device such as camera module incorporated in a mobile telephone, PDA or the like. 
   The invention is not limited to the embodiments or the example as described above, and suitable modification can be made within the range consistent with the content or idea of the invention, which can be read from the claims and the entire specifications, and a display apparatus or a method accompanying such changes is also included in the technical idea of the invention.