JP2011158551A - Camera module and cellular phone - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To miniaturize a camera module with a camera shake correction function, which is incorporated in portable equipment. <P>SOLUTION: A base frame 16 is fixed to a sensor substrate 7 on which an image sensor 15 is mounted. A first frame 20 is supported to be freely movable by a pair of horizontal guides 18a and 18b in the base frame 16. A second frame 32 is supported to be freely movable by a pair of vertical guide shafts 31a and 31b in the first frame 20. A slender first actuator 22 is incorporated in parallel with a top surface in the base frame 16, and a slender second actuator 34 is incorporated in parallel with a side surface in the second frame 32. The first and second actuators 22 and 34 are driven based on a displacement signal obtained from a gyro IC 11, and a lens unit 50 held by the second frame 32 is moved in a plane parallel to an optical axis P to perform camera shake correction. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a camera module that is compactly incorporated into a portable device, and more particularly to a camera module having a function of optically suppressing blurring of an image even when vibration such as camera shake is applied, and a mobile phone including the camera module. Is.

  Digital cameras are also incorporated in mobile terminal devices such as mobile phones and PDFs as camera modules, and their convenience is widely recognized. Such a camera module needs to be much more compact than a general-purpose digital camera. For example, a camera module for a mobile phone is compact so that the length of each side does not exceed approximately 12 mm in terms of a rectangular parallelepiped. Otherwise, the size of the phone body will increase and portability will be impaired.

On the other hand, a high-definition photographed image is required for the camera module, and an image sensor having more than 5M pixels and a photographing optical system for high resolution with four or more lenses are used. Some examples are used. Furthermore, in order to make better use of the performance of such an image sensor and imaging optical system, an AF device that automates focus adjustment, or a camera module equipped with a camera shake correction device that prevents deterioration of image quality due to camera shake during shooting (Patent Document 1) has also been studied, and high-quality images can be taken with a simple operation.

JP 2008-89803 A

  Some camera shake correction devices do not require moving the photographic optical system or image sensor for correction, but this method cannot effectively use part of the image data obtained from the entire shooting screen. Since there is a disadvantage, a camera shake correction device of an optical correction method is used particularly when trying to obtain a high-definition photographed image. The camera shake correction device basically detects the displacement of the housing by a detector such as an acceleration sensor or a gyroscope, and at least a part of the photographing optical system or the image sensor, or the photographing optical system and the image sensor according to the detection signal. Is a structure that offsets the shaking of the housing by displacing the entire camera module. For this reason, a movable part, a support mechanism, and an actuator are indispensable around the photographing lens and the image sensor, which is a factor for increasing the size of the camera module.

  The camera module described in Patent Document 1 is a method of correcting camera shake by shifting a photographing optical system in two directions of an X axis and a Y axis perpendicular to the optical axis with respect to an image plane. The camera module is made compact by arranging elongated piezoactuators in combination with a drive shaft in a direction perpendicular to the optical axis and arranging the elongated piezoactuators in a T shape. However, since the two piezo actuators are arranged on one side with respect to the optical axis of the photographic optical system, mechanical backlash is easily added when each is driven, and the photographic optical system is movably supported. This is disadvantageous when the mechanism vibrates to increase the positioning accuracy of the photographing optical system. Furthermore, as the mounting position of the piezo actuator moves closer to one side of the photographic optical system, the shape when the entire camera module is viewed from the front becomes an elongated rectangular shape on one side of the photographic optical system. There is also a concern that the installation posture of the module may be restricted.

  The present invention has been made in consideration of the above circumstances, and its purpose is to enable sufficient compactness not only in the thickness direction but also in a plane perpendicular to the optical axis, and to further improve the performance of the image stabilization apparatus. It is an object of the present invention to provide a camera module for a portable device that can be used.

  In order to achieve the above object, the present invention shifts a lens unit in which an entire photographing optical system is incorporated into a cylindrical lens barrel with respect to an image sensor in first and second directions perpendicular to the optical axis and perpendicular to each other. Thus, the camera shake correction is performed. The camera module of the present invention includes a base frame fixed to a sensor substrate that holds the image sensor, a first frame that is movably supported by the base frame in the first direction, and the first frame A second frame supported movably in a second direction and holding the lens unit; a drive shaft extending in the first direction; and a first actuator for moving the first frame in the first direction; A second actuator that includes a drive shaft extending in the second direction and that moves the second frame in the second direction as a main constituent member, and the drive shafts of the first and second actuators are substantially separated from the optical axis. It is equidistant and is arranged outside the outer peripheral contour of the lens unit.

  Furthermore, in the present invention, the exterior body is formed in a substantially rectangular parallelepiped shape, the drive shafts of the first and second actuators are parallel to the mutually orthogonal side surfaces of the exterior body, and the number of pixels is 5M pixels or more. One of the features is that a CMOS sensor is used for the image sensor, and the photographing optical system is composed of at least four lenses. Further preferably, the first and second actuators are configured to drive the drive shafts in the axial direction by driving piezoelectric elements to move the first frame and the second frame individually in the first and second directions, respectively. It has become.

  As a more specific structure for correcting camera shake, the piezoelectric element of the first actuator is incorporated in the base frame, the drive shaft of the first actuator is frictionally engaged with the first frame, and the piezoelectric element of the second actuator is A mode is adopted in which the element is incorporated in the second frame and the drive shaft of the second actuator is frictionally engaged with the first frame. The lens unit may be incorporated in the second frame so as to be movable in the optical axis direction, and focusing may be performed by driving a third actuator provided in the second frame. A mobile phone provided with the camera module of the present invention is also included in the present invention.

  A lens unit in which the entire photographing optical system is incorporated in a cylindrical lens barrel is shifted in first and second directions orthogonal to the optical axis and orthogonal to each other to perform camera shake correction. When the camera module is viewed from the front without complicating the structure around the lens unit, the camera shake correction drive shaft extended in the direction is placed at approximately the same distance from the optical axis and outside the outer periphery of the lens unit. The size can be reduced, and the size in the thickness direction can be reduced to make the whole compact. In particular, when the exterior body has a substantially rectangular parallelepiped shape, the camera module is assembled into a substantially square shape by incorporating the pair of drive shafts in parallel with the mutually orthogonal side surfaces of the exterior body, so that the camera module is incorporated into a portable device. It can save a lot of space. Therefore, even when combined with a CMOS sensor with the number of pixels of 5M pixels or more and a photographing optical system having a high imaging performance with four or more lenses, the exterior size of the exterior body is compact to about 13 mm □. Can be realized.

It is an external view which shows the front and back of a mobile telephone. It is an external view of the camera module with the front cover removed. It is a principal part disassembled perspective view of a camera module. It is a principal part vertical sectional view which shows the connection part of the drive shaft of a 1st actuator, and a 1st flame | frame. It is a principal part horizontal sectional view which shows the connection part of the drive shaft of a 1st actuator, and a 1st flame | frame. It is explanatory drawing which shows arrangement | positioning of the drive shaft for camera shake correction | amendment. It is a block diagram which shows the principal part of the electrical structure of a camera module. It is a timing chart which shows the reading cycle of the displacement signal for camera shake correction. It is explanatory drawing which shows the movement process of the lens unit at the time of camera shake correction | amendment. It is a flowchart which shows a camera shake correction process. It is a partial flowchart which shows another example of a camera shake correction process. It is explanatory drawing which shows the movement process of the lens unit by the flow of FIG. It is a partial flowchart which shows another example of camera shake correction processing. It is a partial flowchart which shows the other example of a camera shake correction process.

  FIG. 1 shows the appearance of a mobile phone incorporating the camera module of the present invention. 3A is an appearance on the front side and FIG. 1B is an appearance on the back side. When an input operation is performed from an operation unit provided below the display panel 2, an operation menu is displayed on the display panel 2. The display panel 2 is a touch panel. Thereafter, a dial call operation or the like can be performed by touching an appropriate icon displayed on the display panel 2 with a fingertip.

  As shown in FIG. 2B, a photographing window 3 is provided on the back side of the mobile phone, and a camera module 5 is incorporated in the back thereof. When the camera mode is activated by a touch operation on the display panel 2, an image photographed by the camera module 5 through the photographing window 3 is displayed on the display panel 2 as a through image in real time. If a framing is performed while observing the through image and a release operation is performed at an appropriate timing, a still image can be taken. After starting in the camera mode, if a moving image mode is selected, moving images can be shot. The camera module 5 has a substantially rectangular parallelepiped shape, a front view size of approximately 13 mm × 13 mm □, and a thickness of approximately 10 mm.

  In FIG. 2 showing the appearance of the camera module 5, a mechanism portion 8 of the camera module 5 is incorporated between a front cover 6 and a sensor substrate 7 which are the main parts of the exterior body. Reference numeral 9 denotes a wiring member made of a flexible printed board, which is connected to a terminal drawn out to a required portion of the mechanism portion 8. The sensor substrate 7 is provided with an area-type image sensor, drives a gyro IC 11 incorporating a gyro sensor for detecting the displacement of the camera module 5 and the image sensor, and performs various signal processing on the obtained imaging signal. A connector 13 to which the drive IC 12 and the wiring material 9 are connected is provided.

  In FIG. 3, which shows an exploded view of the main part of the mechanism unit 8, an image sensor 15 is fixed to the sensor substrate 7 via a holder. The image sensor 15 is a 1 / 2.5 type CMOS sensor having 5M pixels. A rectangular frame-shaped base frame 16 is fixed to the front surface of the sensor substrate 7 so as to surround the periphery of the rectangular image sensor 15. The base frame 16 has a vertical side and a horizontal side of about 13 mm each, and a pair of first guide shafts 18a and 18b are horizontally inserted and fixed on the top surface side and the bottom surface side. Although a CCD image sensor can be used instead of the CMOS sensor, the CMOS type is more advantageous in consideration of the power supply capacity of the mobile phone.

  The first frame 20 is assembled to the base frame 16 so as to be movable in the horizontal direction by supporting the pair of first guide shafts 18a and 18b. The first frame 20 is slightly smaller than the base frame 16, and the horizontal movement range is set so as not to contact the inner surfaces of the left and right side walls of the base frame 16. In order to move the first frame 20 in the horizontal direction, the first actuator 22 is incorporated into a frame portion 16 a integrally formed with the base frame 16.

The first actuator 22 includes a piezo element 22b having a weight 22a having a large inertia fixed at a rear end thereof, and a drive shaft 22c having a circular cross section bonded to the piezo element 22b and extending horizontally. A flexible printed board is connected to the piezo element 22b, and the piezo element 22b is finely expanded and contracted in the axial direction by the input of a drive pulse, and the expansion and contraction motion is transmitted to the drive shaft 22c. The speed of the expansion / contraction motion of the piezo element 22b differs depending on the waveform of the input drive pulse, when it expands and when it contracts, and the slower motion is a propulsive force that moves the first frame 20 via the drive shaft 22c. Communicated. Therefore, by driving and controlling the waveform of the drive pulse input to the piezo element 22b, a driving force to the left or right in the horizontal direction can be obtained from the drive shaft 22c. Although it is possible to use a VCM (voice coil motor) instead of a piezo element as a drive source for the actuator, it is small in diameter and easy to miniaturize, and can respond to movement at high speed with high accuracy. It is advantageous to use a piezo element.

  The distal end side of the drive shaft 22 c is inserted into the receiving portion 20 a of the first frame 20. 4 and 5, a flat plate is formed on the outer peripheral surface on the front side of the drive shaft 22c so that the mechanical reciprocation in the axial direction of the drive shaft 22c is accurately transmitted to the first frame 20. The pressing plate 24 is pressed. A receiving plate 23 in which a spring plate is bent in a V shape along a horizontal fold line is incorporated in the receiving portion 20a at a position facing the pressing plate 24. When the bracket 25 is assembled to the receiving portion 20 a together with the compression spring 26 from the front side, the drive shaft 22 c is elastically sandwiched between the receiving plate 23 and the pressing plate 24. Since the receiving plate 23 is incorporated in the first frame 20 so as not to move in the horizontal direction, the propulsive force transmitted from the drive shaft 22c acts to move the first frame 20 in the horizontal first direction.

  In order to detect the amount of movement of the first frame 20 in the horizontal direction relative to the base frame 16, a magnet pair 28 is fixed to the base frame 16. The magnet pair 28 is formed by arranging minute permanent magnets so that the N pole and the S pole are aligned in the horizontal direction, and the first hall element 29 is fixed to the first frame 20 so as to face the magnet. The output from the first Hall element 29 changes in accordance with the relative position with respect to the magnet pair 28, so that the current position signal in the horizontal direction of the first frame 20 can be obtained from the first Hall element 29.

  A second frame 32 is movably supported by a first frame 20 supported by the base frame 16 so as to be movable in the horizontal direction via a pair of guide shafts 31a and 31b extending vertically. The left guide shaft 31a is inserted in the order of the second frame 32, the first frame 20, and the second frame 32, and is fixed to the second frame 32. The right guide shaft 31b is fixed to the first frame 20, and the upper end side thereof is fixed. It is inserted through the guide groove of the second frame 32.

  In order to move the second frame 32 in the vertical direction, the second actuator 34 is incorporated into a frame portion 32 a integrally formed with the second frame 32. Similar to the first actuator 22, the second actuator 34 includes a piezo element 34b having a weight 34a fixed to the rear end thereof, and a drive shaft 34c having a circular cross section bonded to the piezo element 34b and extending vertically upward. A driving pulse is input to the piezo element 34b through the flexible printed board, and its mechanical expansion and contraction motion is transmitted to the first frame 20 through the driving shaft 34c. The first frame 20 is horizontally guided by the guide shafts 18a and 18b. Therefore, the second frame 32 receives a propulsive force in the opposite direction from the first frame 20.

  The distal end side of the drive shaft 34c is inserted into the receiving portion 20b of the first frame 20, and the drive shaft 34c is transmitted so that mechanical reciprocation of the drive shaft 34c is transmitted to the first frame 20 as shown in FIG. A flat pressing plate 36 is pressed against the outer peripheral surface of the front side. A receiving plate 37 in which a spring plate is bent in a V shape with a vertical folding line is incorporated in the receiving portion 20b at a position facing the pressing plate 36. When the bracket 38 is assembled together with the compression spring 39 from the front side of the receiving portion 20b, the driving shaft 34c is sandwiched between the receiving plate 37 and the pressing plate 36 in the same manner as the driving shaft 22c described above, and the propulsive force from the driving shaft 34c. Is accurately transmitted to the first frame 20. As described above, since the first frame 20 is supported by the guide shafts 18a and 18b so as not to move in the vertical direction, the second frame 32 receives a propulsive force in the vertical direction due to mechanical vibration of the drive shaft 34c. And move up or down depending on the waveform of the drive pulse.

  In order to detect the amount of movement of the second frame 32 in the vertical direction relative to the first frame 20, a magnet pair 40 is fixed to the first frame 20. The magnet pair 40 is formed by arranging minute permanent magnets so that the N pole and the S pole are aligned in the vertical direction, and the second Hall element 41 is fixed to the second frame 32 so as to face the magnet. When the second frame 32 moves in the vertical direction with respect to the first frame 20, a position signal in the vertical direction of the second frame 32 is obtained from the second Hall element 41.

  A third actuator 45 is assembled to the second frame 32 from the back side. Similarly to the first and second actuators 22 and 34 described above, the third actuator 45 has a drive shaft 45c coupled to a piezo element 45b having a weight 45a fixed to the rear end thereof, and the drive shaft 45c is parallel to the optical axis P. Projecting forward of the second frame 32. Further, with respect to the optical axis P, a guide pin 46 is provided on the opposite side of the drive shaft 45c so as to protrude in parallel with the optical axis P.

  The drive shaft 45c and the guide pin 46 support the lens unit 50 in which the photographing optical system is incorporated in the cylindrical barrel 48 so as to be movable along the optical axis P. For this reason, a receiving portion 50 a that receives the drive shaft 45 c and a fork-shaped receiving portion 50 b that receives the guide pin 46 are provided on a part of the outer periphery of the lens barrel 48. The receiving portion 50a incorporates a receiving plate similar to the receiving plates 23 and 37 described above, in which the spring plate is bent in a V shape along a fold line parallel to the optical axis P, and the outer peripheral surface of the drive shaft 45c is viewed from the left side. receive. Further, the lens unit 50 incorporates a leaf spring 51 having a similar V-shaped bent portion at the tip, and presses the right side of the outer peripheral surface of the drive shaft 45c toward the receiving plate with the V-shaped tip. Therefore, the drive shaft 45 c is elastically sandwiched between the receiving plate and the tip of the leaf spring 51.

  One of the reciprocating motions of the drive shaft 45c is a driving force that moves the lens unit 50 in the direction of the optical axis P, and the lens unit 50 moves back and forth along the optical axis P according to the waveform of the drive pulse. As is well known, the integral value of the contrast between the pixels included in the image signal for one screen output from the image sensor 15 has a correlation with the in-focus state of the photographing optical system incorporated in the lens unit 50. Thus, focusing can be automated by moving the lens unit 50 in the optical axis direction while monitoring the change in the integrated value.

  A signal plate 53 is fixed to the upper surface of the lens unit 50, and the signal unit 53 is photoelectrically monitored by a reflective photosensor 54 fixed to the second frame 32, so that the lens unit 50 is in a home position for focusing. It is possible to confirm that the camera is positioned at the position or within the specified focus adjustment range.

  A shutter unit 55 is assembled to the second frame 32 so as to cover the second frame 32 and the front surface of the lens unit 50. For this reason, engagement pieces 55c and 55d extending in the form of tongues are formed integrally on the upper and lower surfaces of the shutter unit 55, and are formed in the second frame 32 in locking holes provided in these engagement pieces. The engaging claws 32c and 32d are engaged with each other. The shutter unit 55 is formed with a photographing opening 55a for allowing subject light to pass through a photographing optical system incorporated in the lens unit 50, and further includes a shutter blade 58 (see FIG. 7) for opening and closing the photographing opening 55a, and a shutter blade 58. A shutter actuator such as a rotary solenoid that opens and closes is incorporated. The shutter actuator operates in response to an open / close signal input via the flexible printed board 55b.

  As shown in FIG. 2, the mechanism portion 8 is covered with a sensor board 7 and a rectangular tube-shaped front cover 6 serving as an exterior body of the camera module 5, and is assembled into a substantially rectangular parallelepiped shape as a whole. For this reason, as shown in FIG. 1, it is not necessary to secure a complicatedly shaped installation space inside the phone case when it is installed in a mobile phone, and it is easy to apply to various mobile phones regardless of manufacturer or model. There are advantages. Note that the gyro IC 11, the drive IC 12, and the connector 13 can be fixed to the back surface of the sensor substrate 7. In this case, the camera module 5 can be combined into a complete rectangular parallelepiped shape or a cubic shape.

  The electrical connection between the image sensor 15 and the drive IC 12 and the electrical connection between the gyro IC 11 and the drive IC are performed by printed wiring formed on the sensor substrate 7. In addition, the flexible printed board drawn out from each actuator and sensor used in the mechanism unit 8 of the camera module 5 has its signal terminal connected to a required part of the wiring member 9, and further the wiring member 9 is inserted. The output terminal is connected to the drive IC 12 via the connector 13. The actuators and sensors are controlled at appropriate timing under the control of the system controller mounted on the drive IC 12.

  A structure for camera shake correction in the mechanism unit 8 of the camera module 5 is schematically shown in FIG. The first frame 20 is movable in the horizontal direction by a pair of guide shafts 18 a and 18 b held by the base frame 16. The second frame 32 holding the lens unit 50 movably in the optical axis direction is perpendicular to the first frame 20 by a pair of guide shafts 31 a and 31 b provided between the first frame 20 and the second frame 32. It is movable.

  When the camera module 5 is viewed from the front, the drive shaft 22c of the first actuator 22 incorporated in the base frame 16 extends in the horizontal direction so as to overlap the guide shaft 18a, and is received by the receiving portion 20a of the first frame 20. Friction engagement. Similarly, the drive shaft 34c of the second actuator 34 incorporated in the second frame 32 extends in the vertical direction so as to overlap the guide shaft 31a in the front-rear direction, and is frictionally engaged with the receiving portion 20b of the first frame 20. . Then, as shown in the figure, the shaft core lines 22x and 34x of the drive shafts 22c and 34c are located outside the outer contour of the lens unit 50, and are provided at positions where the distances A and B from the optical axis P are substantially equal. ing.

  As described above, in addition to the guide shafts 18b and 31b provided at positions sandwiching the optical axis P with respect to the drive shafts 22c and 34c, the guide shafts 18a and 31a extending in the same direction approaching the drive shafts 22c and 34c. By preventing the drive force of the drive shafts 22c and 34c from being transmitted to the first frame 20 and the second frame 32 as a rotational moment, the frames 20 and 32 can be smoothly moved horizontally and vertically. This also has the effect of reducing drive noise.

Further, when incorporating the first and second actuators 22 and 34 that are elongated in the axial direction in a layout in which the shaft cores 22x and 34x are orthogonal to each other, the longitudinal directions of the first and second actuators 22 and 34 are as described above. It is best in terms of space efficiency to make the front cover 6 parallel to the top surface and the side surface of the front cover 6, which is advantageous for making the entire camera module 5 compact. In addition, the camera module 5 can be made compact in the thickness direction by setting these assembling positions outside the outer peripheral contour of the lens unit 50 having a substantially cylindrical shape.

  In the illustrated form, the first frame 20 is moved in the first direction by driving the first actuator 22 incorporated in the base frame 16, and the second direction is driven by driving the second actuator 34 incorporated in the second frame 32. The second frame 32 is moved in the second direction by a reaction against the first frame 20 that is prevented from moving to the second frame 32. To move the second frame 32 in the second direction, the first frame It is also possible to adopt a structure in which the second actuator 34 is incorporated in 20 and the second frame 32 is moved by driving the second actuator 34. However, when a piezo element is used as a drive source for the first and second actuators 22 and 34, mechanical vibrations and frictional sounds associated with the expansion and contraction motion are reduced, and the first and second frames 20 and 32 are mounted. The illustrated configuration is more advantageous for smooth and highly accurate movement.

  The operation of the present invention will be described below with reference to FIG. 7 schematically showing the electrical configuration of the camera module 5. When the cellular phone is operated in the camera mode for taking a still image, the shutter driver 56 is activated in response to an activation signal from the system controller 62 that controls the sequential operation of the camera module 5, and the shutter blades 58 are photographed by the shutter actuator 57. The opening 55a is held at the open position where it is fully opened.

  A subject image is formed on the photocathode of the image sensor 15 through a four-lens imaging optical system 60 incorporated in the lens barrel 48. Further, a drive signal for capturing a through image is supplied from the CMOS driver 63 to the image sensor 15. As a result, the image sensor 15 is driven by a rolling shutter system, and the image pickup signals are sequentially read out for each screen while the shutter blades 58 are kept fully open. When readout of an image pickup signal is performed by the rolling shutter method, a reset signal is sequentially sent out for each pixel array line of the image sensor 15 as shown in FIG. 8, and thereafter, for each line of the pixel array after the exposure time T0 has elapsed. The imaging signal is read out sequentially. Therefore, exposure is not performed on all the pixels of the image sensor 15 at the same time, and exposure and readout of the imaging signal are performed in a line sequential manner.

  The image pickup signal read out in this way is input to the image signal processing circuit. The image signal processing circuit 64 performs known signal processing such as first-stage amplification, gain adjustment, A / D conversion, and the like on the image pickup signal input for each pixel in one screen unit, and generates a bus line 65 as digitized image data. To supply. The image data for one screen supplied to the bus line 65 is temporarily stored in the flash memory 66 and then read out by the image data processing IC 67 to be subjected to matrix calculation, signal interpolation, γ correction, luminance / color difference conversion, data. Image processing such as compression is performed. The image data for one screen is sequentially sent to the display panel 2 by the monitor driver 68, and a through image is displayed on the display panel 2.

While the through image is being displayed, image data for one screen is subsequently read sequentially, so that the brightness of the next screen can be adjusted according to the luminance information of the previous screen. This adjustment can be dealt with not only by changing the exposure time T0 but also by adjusting the aperture diameter of the aperture, inserting / removing the ND filter, adjusting the gain of the imaging signal, and the like. Further, the AF processing unit 69 calculates an AF evaluation value based on the image data for each screen. The system controller 62 monitors the AF evaluation value calculated for each screen, and sends an AF control signal to the AF-PZ driver 70 so that the AF evaluation value becomes the maximum value.

  The AF-PZ driver 70 sends a drive pulse to the third actuator 45 in response to the input AF control signal. As a result, the lens unit 50 held by the second frame 32 moves back and forth in the direction of the optical axis P according to the input waveform of the drive pulse, and is automatically focused by the feedback method. Depending on the lens configuration of the photographic optical system 60, it is possible to focus by moving a part of the lens in the optical axis direction, but it is structurally complicated and unsuitable for downsizing. Therefore, it is better to focus by moving the entire lens unit 50 including the shutter unit 55 as described above.

When framing is performed while observing the through image displayed on the display panel 2 and a release button assigned for still image shooting is pressed at an appropriate timing, a release signal is input to the system controller 62 via the bus line 65. Is done. When the release signal is input, the system controller 62 controls the shutter driver 56 and the CMOS driver 63 to operate in the actual photographing sequence.

  In this shooting sequence, shooting with a mechanical shutter using the shutter blades 58 is performed instead of the rolling shutter at the time of through image shooting. As shown in FIG. 8, in response to the input of the release signal, first, a global reset process is performed in which all the pixels of the image sensor 15 are simultaneously reset by the CMOS driver 63. This global reset processing is forcibly performed in such a way as to interrupt shooting with a rolling shutter at the time of through image shooting. Therefore, a subject image based on image data for one screen read before that is displayed on the display panel 2. Will remain.

  Immediately after the completion of the global reset process, exposure is started simultaneously on all the pixels of the image sensor 15, and the shutter blades 58 are closed after the exposure time T1 has elapsed. The exposure time T1 is generally determined so as to coincide with the exposure time for one screen read immediately before the release signal is input. By closing the shutter blades 58, the exposure for all the pixels of the image sensor 15 is completed simultaneously. Therefore, unlike the case of shooting with a rolling shutter, all pixels start exposure at the same time and end exposure at the same time.

  The exposure ends when the shutter blade 58 is closed, but the shutter blade 58 is continuously held at the closed position for a certain time T2. While the fixed time T2 elapses, an image signal for one main photographing image taken at the exposure time T1 is read. The image pickup signal is read out in a line-sequential manner for each line of the pixel array. During that time, since the shutter blades 58 are fully closed, all the pixels are in a light shielding state. The read image signal is sent to the image data processing IC 67 through the image signal processing circuit 64 in the same way as when shooting a through image, and the image data for one main shooting screen is secured in a predetermined address area of the flash memory 66. Recorded in the memory area. Since the actual captured image recorded in this way is due to the simultaneous exposure of all pixels, even if the subject is moving, there is no noticeable deformation in the recorded image.

  The shutter blades 58 are fully opened after completion of reading of the imaging signal for one screen obtained in the main photographing. When the shutter blades 58 are fully opened, the system controller 62 returns to the original through image shooting sequence and performs shooting with the rolling shutter.

  On the other hand, when the operation is started in the camera mode, camera shake correction processing is performed in parallel, and a displacement signal corresponding to the acceleration of the camera shake displacement applied to the casing of the mobile phone is activated by the operation of the gyro sensor incorporated in the gyro IC 11. The data is sent to the bus line 65. The displacement signal thus input is normally read by the system controller 62 every sampling period Ta as indicated by “A” in FIG. As shown by “B” in the figure, the displacement signal can be read at a sampling period Tb having a period about twice that of Ta, and these are switched and used as necessary. Also good.

  While the camera shake correction process is performed, the current position of the lens unit 50 is detected at a shorter period than the sampling period Ta for reading the displacement signal. The current position of the lens unit 50 can be detected as a position signal obtained by combining the horizontal position signal and the vertical position signal obtained individually from the Hall elements 29 and 41. For example, when the sampling period Ta for reading the displacement signal is 1 msec, the current position of the lens unit 50 is detected at a period of 0.1 msec, and the position of the lens unit 50 is adjusted every detection period.

As shown in the flowchart of FIG. 10, the system controller 62 is a lens unit necessary for correcting the optical axis shake of the imaging optical system 60 due to the displacement based on the displacement signal read at each sampling period Ta that is initially set. calculating a target position _{L M} 50. Subsequently, signals from the first and second Hall elements 29 and 41 are read, and the current position _LN of the lens unit 50 is detected. When the current position L _N is detected, a comparison with the target position L _M is performed, and the number of drive pulses supplied to the first and second actuators 22 and 34 is determined according to the absolute value of the difference. The supply number of drive pulses is set between the detection one period of the current position L _N to a maximum of 10 for example, close to the maximum number enough away the current position L _N with respect to the target position L _M, current position _{L N} is less closer to the target position _{L M.}

The first and second piezo elements 22b and 34b perform one expansion / contraction every time one driving pulse is input, and generate a driving force in either the expansion period or the contraction period according to the waveform of the driving pulse. The driving force generated by the first and second piezo elements 22b and 34b is transmitted to the first and second drive shafts 22c and 34c, and drives the first and second frames 20 and 32 via the receiving portions 20a and 20b, respectively. Move a certain distance per pulse. Accordingly, the moving distance during one detection cycle of the current position _LN is determined by the number of driving pulses supplied to the first and second actuators 22 and 34, and the moving direction is determined by the waveform of the supplied driving pulse. However, the first and second drive shafts 22c and 34c move the first and second frames 20 and 32 by frictional engagement with the receiving plate and the pressing plate incorporated in the receiving portions 20a and 20b. It is inevitable that there is an error. Therefore, as described above, the movement of the lens unit 50 is adjusted while periodically detecting the current position _LN .

The system controller 62 checks the difference between the target position _{L M} while monitoring the current position _{L N} as described above, to drive the X-PZ driver 74, Y-PZ driver 75. The first is to the current position _{L N} reaches the target position _{L M,} a second actuator 22, 34 forward (FWD) driven, after the current position _{L N} has exceeded the target position _{L M} Reverse (REV) To drive. Of course, after the current position in either the horizontal direction or the vertical direction exceeds the target position, only one of them is switched to REV driving.

When the current position L _N of the next cycle is detected and compared with the target position L _M similarly, first when the two sets match, the drive of the second actuator 22, 34 is stopped. A new displacement signal is read again after the first sampling period Ta has elapsed, and the same procedure is repeated. This is shown in FIG. Based on the displacement signal read by "0" time, when the target position L _M is calculated, as the current position L _N to up to at least the sampling period Ta (1 msec) elapses matches the target position L _M, A lens position adjustment process is performed in a plane perpendicular to the optical axis. This adjustment process is performed for each detection cycle of the current position _LN indicated by a broken line.

At the time “0”, since the difference between the current position L _N (= L0 position) and the target position L _M (= L1 position) is large, the maximum number is 10 during one detection period of the current position L _N. Are input to the first and second actuators 22 and 34. As a result, the lens unit 50 moves with the maximum amount of movement. Subsequently, since the current position L _N detected at the time “n1” is also far from the target position L _{M, the} lens unit 50 is similarly linearly moved with the maximum amount of movement by the ten drive pulses. Moved towards position.

Since the current position L _N detected at the time “n2” is close to the target position L _M , the number of drive pulses supplied is limited. For example, after five drive pulses are supplied, the supply of the drive pulses is cut off. For this reason, the lens unit 50 remains stopped without moving until the “n3” time point when the current position _LN is detected next. However, in the illustrated example, has exceeded a previously target position L _M is the stop position, the current position L _N detected by "n3" point thus is detected as being slightly exceeds the target position L _M.

Drive pulse input Therefore the "n3" after the time switches on the waveform of the REV drive, also slight because also the difference between the target position L _M, for example, REV driven by four driving pulses. Thus, by FWD drive and REV driving is repeated for each detection period of the current position L _N, the current position L _N of the lens unit 50 matches the target position L _M, thereafter new current position L _N Even if detection is performed, the lens unit 50 remains stopped.

The displacement signal reading cycle Ta elapses when 1 msec has elapsed from the time point “0” at which the first current position L _N was detected, and the next new displacement signal is read. In general, the displacement signal reading period Ta (= 1 msec) is set to be sufficiently short with respect to the period of camera shake displacement, so that the newly read displacement signal is hardly different from the displacement signal read immediately before. Therefore, the target position L _M is determined based on the loaded displacement signal newly, from a straight line position on L2 shown by the dashed line in FIG. 9 (A), the lens unit 50 is L2 located in the same path as the previous To adjust the position. By repeating such movement adjustment processing every time the sampling period Ta and the current position detection period elapse, even if various hand movements are added to the housing, the displacement signal that is sequentially read in a fine period, and further finer The lens unit 50 is moved and adjusted following the current position signal sequentially detected in a cycle, so that a favorable camera shake correction function can be obtained.

In the above-described camera shake processing, the expansion and contraction of the first and second piezoelectric elements 22b and 34b is transmitted to the first and second drive shafts 22c and 34c as mechanical vibrations, and the first and second vibrations are driven by the vibrations of these drive shafts. Since this is performed by moving the frames 20 and 32, mechanical vibration noise is likely to be produced. In particular, immediately after a drive pulse is input to the first and second piezoelectric elements 22b and 34b in a stationary state, or immediately after switching the waveform of the input drive pulse, the first and second frames 20 and 32 are added. Since the acceleration changes greatly, the vibration noise also increases. This means that vibration noise is likely to be generated at the bending point on the route line of the current position _LN shown in FIG.

Even if the vibration sound generated in this way is not so loud, for example, when recording in parallel with the shooting of a movie, there is a disadvantage that it is recorded as noise. It is preferable to keep it. In order to reduce the vibration noise, it is preferable to reduce the number of inflection points appearing on the route line of the current position _LN during the movement adjustment process, and to reduce the change in acceleration by suppressing the speed of movement adjustment. For this purpose, it is most convenient to lengthen the displacement signal reading cycle as shown by “B” in FIG. 8, and to increase the current position detection cycle accordingly.

For example, when the sampling period Tb for reading the displacement signal indicated by “B” in FIG. 8 is 2 msec and the detection period of the current position is 1/10 of the reading period Tb, 2 msec has elapsed as shown in FIG. 9B. In the meantime, the number of bending points appearing on the route line of the current position _LN is “4” including the time “0”. On the other hand, since “12” inflection points appear in 2 msec in FIG. 9A, FIG. 9B is much more effective in preventing the generation of vibration noise. However, since the resolution of the displacement signal reading becomes coarse and the accuracy of camera shake correction is somewhat lowered, it is preferable that these can be properly used as necessary. For example, it is effective to perform camera shake correction in the normal mode shown in FIG. 5A during still image shooting and in the silent mode shown in FIG. 5B during moving image shooting, and switching can be automated.

As described above, it is possible to suppress the generation of vibration sound at the time of camera shake correction only by extending the sampling cycle for reading the displacement signal and the detection cycle of the current position. In addition, the method shown in the partial flowchart of FIG. You can also reduce vibration noise. The flowchart shown in FIG. 10 is commonly used except for the partial flow of FIG. In the method shown in FIG. 11, when the current position L _N exceeds the target position L _M , it is determined whether camera shake correction is in the normal mode or the silent mode, and only when the silent mode is selected, the REV is selected. The drive is not performed, and the movement adjustment of the lens unit 50 is finished at that time.

According to the above process, it is omitted from the current position L _N Under silent mode detected by "n3" point as shown in FIG. 12 exceeds the target position L _M, even after that detects the current position L _N Then, the lens unit 50 remains stopped until a new displacement signal is read after 1 msec. Then, after reading the new displacement signal is made performed the same processing, also the current position L _N is moved and adjusted in the lens unit 50 at the time of exceeding the target position L _M is completed.

In the movement process immediately before the current position L _N exceeds the target position L _M , L _N is almost close to the target position L _M. Therefore, first, the second piezoelectric element 22b, the number of drive pulses input to the 34b joined by limiting, since the stop position of the lens unit 50 can not greatly exceed the target position L _M, moved and adjusted at that time Even if the operation is interrupted, the adjustment position is practically sufficient. If the REV drive is prohibited in this way, even if the sampling period Ta is set to 1 msec and the current position detection period is set to 0.1 msec, the bending point appears on the route line of the current position _LN within 2 msec. The number of “4” becomes “4”, and vibration noise can be suppressed.

  In the lens movement process under the silent mode described above, the lens unit 50 is stopped at the overcorrection position beyond the target position, and that position becomes the current position. The difference between the current position after overcorrection and the target position is calculated in advance. Compared with the set threshold value Δ, only when the threshold value Δ is exceeded, the REV drive may be performed as shown in the partial flowchart of FIG. Further, as shown in the partial flowchart of FIG. 14, when the current position after overcorrection exceeds the threshold value Δ, camera shake correction may be performed by an electronic correction method instead of REV driving. Even when the sampling period for reading the displacement signal is extended to Tb, the control methods shown in FIGS. 11 to 14 can be used in combination.

The camera shake correction by the electronic correction method is based on the current position of the lens unit 50 when the image data for one screen to be recorded is cut out from all the image data based on the imaging signal read from the entire imaging area of the image sensor 15. By adjusting the cutout range in accordance with the difference from the target position, the screen shift due to camera shake is adjusted, and the first and second actuators 22 and 34 are not driven. Therefore, a part of the camera shake correction process can be performed only by electrical image data processing, and the generation of mechanical vibration noise can be reduced.

Note that, when camera shake correction by the electronic correction method is performed, a part of an imaging signal obtained from the entire imaging area of the image sensor 15 cannot be used for image data for one screen to be recorded. For this reason, although it is disadvantageous when trying to increase the definition of an image, if it is a camera module using the image sensor 15 having 5M pixels or more, even if a part of it is used for camera shake correction processing. The sharpness of the image is not greatly deteriorated.

  As described above, the description has been given based on the illustrated embodiment, but a CCD type sensor can be used as the image sensor 15 used in the present invention. When a CCD image sensor is used, the mechanical shutter is not necessary because the image sensor itself has a so-called electronic shutter function. Further, even if the first and second actuators 22 and 34 for correcting camera shake are VCMs as long as they have an elongated shape and move the first and second frames 20 and 32 in the longitudinal direction (axial direction). Even when a (voice coil motor) or the like is used, the present invention can be effectively used.

  Similarly, for the AF third actuator 45, it is only necessary to move the photographic optical system 60 by turning on / off the electromagnet if the VCM, the stepping motor, or focusing is performed in two stages. Note that if a pan-focus system is used as the photographing optical system 60, the autofocus function can be omitted. In addition, the sampling periods Ta and Tb for reading the displacement signal for correcting camera shake and the detection period of the current position are not limited to the values exemplified in the above embodiment, but the structure of the first and second actuators, the structure of the mechanism unit 8, and the like. It can be set appropriately according to

5 Camera Module 7 Sensor Board 9 Wiring Material 15 Image Sensor 16 Base Frame 20 First Frame 22 First Actuator 32 Second Frame 34 Second Actuator 45 Third Actuator 50 Lens Unit 55 Shutter Unit

Claims (7)

A lens unit in which a photographing optical system combining a plurality of lenses is incorporated in a cylindrical barrel; and an image sensor that picks up an optical image formed by the photographing optical system, and an optical axis of the photographing optical system A camera module that performs camera shake correction by moving the lens unit in first and second directions that are orthogonal to each other and orthogonal to each other.
A base frame fixed to a sensor substrate holding the image sensor;
A first frame supported movably in the first direction by the base frame;
A second frame supported by the first frame so as to be movable in the second direction and holding the lens unit;
A first actuator including a drive shaft extending in the first direction and moving the first frame in the first direction;
A second actuator including a drive shaft extending in the second direction and moving the second frame in the second direction;
A camera module, wherein the drive shafts of the first and second actuators are disposed substantially equidistant from the optical axis and outside the outer contour of the lens unit.   The camera module according to claim 1, wherein the exterior body is configured in a substantially rectangular parallelepiped shape, and the drive shafts of the first and second actuators are parallel to the mutually orthogonal side surfaces of the exterior body.   3. The camera module according to claim 1, wherein a CMOS sensor having a number of pixels of 5M pixels or more is used for the image sensor, and the photographing optical system is composed of at least four lenses. .   The first and second actuators respectively drive the drive shafts in the axial direction by driving a piezo element to move the first and second frames individually in the first and second directions. Item 4. The camera module according to any one of Items 1 to 3.   The piezoelectric element of the first actuator is incorporated in the base frame, the drive shaft of the first actuator is frictionally engaged with the first frame, the piezoelectric element of the second actuator is incorporated in the second frame, and the second actuator 5. The camera module according to claim 4, wherein the drive shaft is frictionally engaged with the first frame.   6. The camera module according to claim 5, wherein the lens unit is incorporated in the second frame so as to be movable in the optical axis direction, and focusing is performed by driving a third actuator provided in the second frame. .   A mobile phone comprising the camera module according to claim 1.

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