JP2011160066A - Camera shake correcting device and method, camera module, and cellular phone - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce drive noise by reducing the number of times of driving start and stopping in a camera shake correcting operation of a camera shake correcting device. <P>SOLUTION: In motion picture taking in which noise decreasing performance of the camera shake correcting device is desired, a sampling period Tb for reading a displacement signal from a gyro IC, and a present position detecting period Ts for detecting the present position of a lens unit. are made to be longer than a sampling period Ta and a present position detecting period Tk in still picture taking, respectively. Thus, bending points on a route line of the present position LN in which drive noise is easily generated from the camera shake correcting device, are remarkably reduced, which reduces the drive noise. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a camera shake correction apparatus and method that optically suppresses image blur due to vibration such as camera shake, a camera module including the camera shake correction apparatus, and a mobile phone including the camera module.

  When hand-held shooting is performed with a photographic device such as a digital camera, the optical axis of the photographic lens is moved relative to the subject due to minute vibrations generated by the photographic device, and “camera shake (camera shake)” appears in the photographed image. The subject image may be blurred. As a device for correcting such camera shake, a camera shake correction device is known.

  The camera shake correction device is an electronic correction method that corrects camera shake by processing captured image data, and at least a part of the shooting optical system or an image sensor, or an entire camera module that integrates the shooting optical system and the image sensor. There is an optical correction method that corrects camera shake by moving the lens. In the electronic correction method, there is a disadvantage that a part of the image data obtained from the entire shooting screen cannot be effectively used. Therefore, when trying to obtain a high-definition shot image, an optical correction type image stabilization device is used. ing.

  An optical correction type camera shake correction device causes a camera shake detector such as an angular velocity sensor or a gyroscope to detect vibration generated in the photographing apparatus, and reads a displacement signal corresponding to the camera shake displacement from the camera shake detector every predetermined sampling period. Based on this displacement signal, a target position of a correction lens or the like, which is a correction means for correcting camera shake, is calculated. In addition, the current position detector that detects the current position of the correction lens, etc., detects the current position of the correction lens for each current position detection cycle shorter than the sampling cycle, and controls the actuator by feedback control so that the current correction lens is It is moved from the position toward the target position (see, for example, Patent Document 1).

  Since the optical correction type camera shake correction apparatus moves correction means such as a correction lens and an image sensor by an actuator, a driving sound is generated in the camera shake correction operation. When a still image is taken with a digital camera, even if a slight drive sound is generated from the camera shake correction device, it does not matter. However, in moving image shooting with audio recording, the driving sound of the camera shake correction device is recorded as noise. In order to reduce the drive sound of the camera shake correction apparatus, an imaging apparatus has been invented in which the drive current supplied to the camera shake correction apparatus is lower than normal (see, for example, Patent Document 2).

JP 2008-089803 A JP 2006-074652 A

  In order to investigate the cause of the drive sound generated from the camera shake correction device, as shown in Patent Document 1, the piezoelectric element, the drive shaft that reciprocates according to the expansion and contraction of the piezoelectric element, and the frictional engagement with the drive shaft. A camera shake correction apparatus that performs camera shake correction by a drive mechanism including a driven body to be moved was repeatedly driven and paused every 10 ms, and the level of drive sound generated at that time was observed with an oscilloscope. FIG. 11 is a graph showing the waveform of the observation result, and the drive start and drive stop are indicated by a solid line and a broken line. As is apparent from this observation result, the camera shake correction device emits a loud drive sound when driving is started and stopped, and the drive sound is relatively low while the camera shake correction device is continuously driven. Therefore, it can be seen that in order to reduce the driving sound of the camera shake correction device, the number of times of starting and stopping the driving should be reduced. However, in the camera shake correction apparatus described in Patent Document 2, the number of times of starting and stopping the driving does not decrease even when the driving current is reduced.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to reduce the drive sound by reducing the number of driving start and stop times during the camera shake correction operation of the camera shake correction apparatus.

  The camera shake correction apparatus of the present invention includes camera shake detection means, current position detection means, camera shake control means, and correction mode switching means. The camera shake detection means detects camera shake occurring in the optical device and outputs a displacement signal corresponding to the camera shake displacement. The current position detection means detects the current position of the correction means that moves in a direction orthogonal to the photographing optical axis of the optical device and corrects camera shake. The camera shake control means reads the displacement signal from the camera shake detection means at every sampling period, calculates a target position for moving the correction means to eliminate camera shake based on the displacement signal, and sets the current position detection means to the current position of the correction means. Is detected for each current position detection period shorter than the sampling period, and the correction means is moved from the current position toward the target position. The correction mode switching means is between the first camera shake correction mode in which the sampling period is set to the first sampling period and the second camera shake correction mode in which the second sampling period is set to be longer than the first sampling period. Switch with.

  Furthermore, in the camera shake correction apparatus of the present invention, the correction mode switching means sets the current position detection cycle to the first current position detection cycle in the first camera shake correction mode, and the first current position detection cycle in the second camera shake correction mode. A second current position detection cycle longer than the current position detection cycle is set.

  Further, the correction mode switching means sets the movement speed of the correction means to the first movement speed in the first camera shake correction mode, and the second movement slower than the first movement speed in the second camera shake correction mode. You may set it to speed.

  The correction mode switching means preferably switches the camera shake correction mode according to the operation mode of the optical device. Specifically, it is preferable to switch to the first camera shake correction mode when the operation mode of the optical device is the still image shooting mode, and to switch to the second camera shake correction mode when the operation mode is the moving image shooting mode. Further, the second sampling period is preferably at least twice as long as the first sampling period.

  The camera shake correction method of the present invention includes a first camera shake correction mode in which a sampling period for reading a displacement signal corresponding to a camera shake displacement from the camera shake detection means is set as a first sampling period, and a second longer than the first sampling period. Switching between the second camera shake correction mode set at the sampling period and the target position of the correction means for reading the displacement signal at each sampling period and moving in the direction orthogonal to the photographing optical axis to correct the camera shake. And a step of causing the current position detection means to detect the current position of the correction means for each current position detection period shorter than the sampling period, and moving the correction means from the current position toward the target position.

  Furthermore, the camera shake correction method of the present invention sets the current position detection cycle to the first current position detection cycle in the first camera shake correction mode, and is longer than the first current position detection cycle in the second camera shake correction mode. 2 is set to the current position detection cycle.

  Further, the movement speed of the correction means is set to the first movement speed in the first camera shake correction mode, and is set to the second movement speed that is slower than the first movement speed in the second camera shake correction mode. preferable.

  The camera module of the present invention includes a lens unit in which a photographing optical system in which a plurality of lenses are combined is incorporated in a cylindrical lens barrel, an image sensor that captures an optical image formed by the photographing optical system, and the above-described camera shake. And a correction device, which moves the lens unit as correction means for correcting camera shake. The number of pixels of the image sensor used in the camera module of the present invention is preferably 5M pixels or more. A mobile phone provided with the camera module of the present invention is also included in the present invention.

  According to the present invention, by increasing the sampling period for reading the displacement signal from the camera shake detection means, it is possible to reduce the number of times the camera shake correction apparatus is started and stopped. As a result, the drive sound of the camera shake correction device can be reduced, and therefore it is possible to prevent the drive sound from being recorded as noise during moving image shooting.

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 graph which shows the observation result of the drive sound of a camera shake correction apparatus.

  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. It is possible to use a VCM (voice coil motor) or STM (stepping motor) instead of a piezo element as the actuator drive source, but it is small in diameter and easy to miniaturize, has high response and high movement control. It is advantageous to use a piezo element because it can be performed with high accuracy.

  The distal end side of the drive shaft 22 c is inserted through 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 31 a is inserted through the second frame 32, the first frame 20, and the second frame 32 in this order, and is fixed to the second frame 32. The right guide shaft 31 b is fixed to the first frame 20, and the upper end side thereof is inserted into 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. The shutter unit 55 includes a pair of engagement pieces 55 c and 55 d that protrude toward the second frame 32 on the upper and lower surfaces thereof, and these engagement pieces 55 c and 55 d are provided on the upper and lower surfaces of the second frame 32. The engaged claws 32c and 32d are respectively engaged. 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 (see FIG. 3).

  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.

  Hereinafter, imaging processing and camera shake correction processing will be described with reference to timing charts shown in FIGS. 7 and 8 schematically showing an electrical configuration of the camera module 5. When the mobile phone is operated in the still image shooting mode, 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 open the shooting opening 55 a by the shutter actuator 57. It is held in the fully open position.

  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 image signals for one screen are sequentially read out 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, and A / D conversion on the imaging signal input for each pixel in one screen unit, and outputs the digitized image data to the bus line 65. 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 sequentially read, 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 when shooting a through image. 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 process is forcibly performed in such a way as to interrupt the shooting by the rolling shutter at the time of through image shooting. Therefore, the subject image based on the image data for one screen read before that is still displayed on the display panel 2.

  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 still image shooting mode, camera shake correction processing is performed in parallel. The camera shake correction processing of the present embodiment includes a first camera shake correction mode executed in the still image shooting mode and a second camera shake correction mode executed in the moving image shooting mode. The first camera shake correction mode is a mode that focuses on the performance of camera shake correction, and the second camera shake correction mode is a mode that focuses on quietness. The system controller 62 corresponding to the camera shake control means and the camera shake correction mode switching means of the present invention switches the camera shake correction mode according to the current shooting mode.

  Hereinafter, the first camera shake correction mode will be described. The gyro IC 11 operates a built-in gyro sensor, and sends a displacement signal to the bus line 65 in accordance with the acceleration of the hand movement displacement applied to the casing of the mobile phone. The displacement signal thus input is read by the system controller 62 every sampling period Ta as indicated by “A” in FIG. While the camera shake correction process is performed, the current position of the lens unit 50 is detected at a shorter current position detection period Tk than the sampling period Ta in which the displacement signal is read. 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 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 preset sampling period Ta. The target position LM of the unit 50 is calculated. 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 LN is detected, it is compared with the target position LM, 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 number of drive pulses supplied is set to, for example, 10 at maximum during one detection period of the current position LN, and the closer the current position LN is to the target position LM, the closer to the maximum number, the current position LN. Decreases toward the target position LM.

  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 driving shafts 22c and 34c, and the first and second frames 20 and 32 are respectively transmitted through the receiving portions 20a and 20b. Move by a fixed distance per drive pulse. Therefore, 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 from the target position LM while monitoring the current position LN as described above, and drives the X-PZ driver 74 and the Y-PZ driver 75. The first and second actuators 22 and 34 are driven forward (FWD) until the current position LN reaches the target position LM, and reverse (REV) is driven after the current position LN exceeds the target position LM. 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 LN of the next cycle is detected, the current position LN is compared with the target position LM, and when the two coincide, the driving of the first and second actuators 22 and 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. When the target position LM is calculated based on the displacement signal read at time “0”, the optical axis and the optical axis are set so that the current position LN matches the target position LM at least before the sampling period Ta (1 msec) elapses. Lens position adjustment processing is performed in a vertical plane. This adjustment process is performed for each current position detection cycle Tk of the current position LN indicated by a broken line.

  At the time “0”, since the difference between the current position LN (= L0 position) and the target position LM (= L1 position) is large, 10 drive pulses, which is the maximum number, are detected during one detection cycle of the current position LN. Is 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 LN detected at time “n1” is also far away from the target position LM, the lens unit 50 is similarly linearly moved to the L1 position with the maximum movement amount by 10 drive pulses. Moved towards.

  Since the current position LN detected at the time “n2” is close to the target position LM, 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 next detected. However, in the illustrated example, the stopped position has already exceeded the target position LM, and therefore the current position LN detected at the time “n3” is detected as slightly exceeding the target position LM.

  For this reason, the drive pulse input after the “n3” time point is switched to the waveform of the REV drive, and the difference from the target position LM is small, so the REV drive is performed with, for example, four drive pulses. As described above, the FWD drive and the REV drive are repeated for each detection cycle of the current position LN, so that the current position LN of the lens unit 50 matches the target position LM. Thereafter, the current position LN is newly detected. The lens unit 50 remains stopped.

  When 1 msec has elapsed from the time “0” at which the first current position LN was detected, the displacement signal reading cycle Ta has elapsed, 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, since the target position LM determined based on the newly read displacement signal is the position L2 on the straight line shown by the alternate long and short dash line in FIG. 9A, the lens unit 50 moves to the L2 position through the same path as the previous time. Move to adjust the position. By repeating such movement adjustment processing every time the sampling period Ta and the current position detection period Tk elapse, even when 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 camera shake correction process, 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 frames are vibrated by the vibrations of these drive shafts. Since it is performed by moving 20 and 32, a mechanical drive sound is easy to generate. As described with reference to the graph of FIG. 11, the camera shake correction device switches the waveform of the input drive pulse immediately after the drive pulse is input to the first and second piezo elements 22b and 34b in a stationary state. Immediately after that, since the acceleration applied to the first and second frames 20 and 32 changes greatly, the vibration noise also increases. This means that drive sound is likely to be generated at the bending point on the route line of the current position LN shown in FIG.

  Even if the drive sound generated in this way is not so loud, for example, when recording in parallel with the shooting of a moving image, there is a disadvantage that it is recorded as noise. It is preferable to keep it. Therefore, in the present embodiment, when the mobile phone is set to the moving image shooting mode, the second camera shake correction mode with excellent silence is executed.

  In order to reduce the driving sound, 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, as shown by “B” in FIG. 8, it is easiest to make the sampling period Tb for reading the displacement signal longer than that in the first camera shake correction mode, and to increase the current position detection period Ts accordingly. It is. In addition, the speed of movement adjustment can be increased by setting the maximum number of drive pulses supplied to the first and second piezoelectric elements 22b and 34b during the current position detection cycle to 10 as in the first camera shake correction mode. The change in acceleration can be reduced by suppressing the change.

  For example, when the sampling period Tb for reading the displacement signal indicated by “B” in FIG. 8 is 2 msec and the current position detection period Ts is 0.2 msec which is 1/10 of the sampling period Tb, as shown in FIG. The number of inflection points appearing on the route line of the current position LN during the elapse of 2 msec is “4” including the time “0”. On the other hand, since “12” inflection points appear in 2 msec in FIG. 6A, FIG. 5B is much more effective in preventing the generation of drive sound. However, although the resolution of displacement signal reading becomes coarse and the accuracy of camera shake correction is somewhat lowered, the adverse effect on moving image shooting is small.

  In the above embodiment, the sampling period and the current position detection period are switched according to the camera shake correction mode, and the change in acceleration is reduced by suppressing the moving speed of the lens unit 50. For example, only the sampling period or the sampling period and Even if only the current position detection cycle is switched, the number of bending points appearing on the route line of the current position LN can be reduced, so that the driving sound can be reduced. Further, although the lens unit 50 is moved as the correcting means, the present invention can also be applied to a camera shake correcting apparatus that moves the image sensor 15. Furthermore, although the camera module has been described as a camera shake correction mechanism, the present invention can also be applied to a camera shake correction apparatus that is directly incorporated in a photographing apparatus such as a digital camera.

  Further, 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), STM (stepping motor) or the like is used, the present invention can be effectively used. Note that the sampling periods Ta and Tb and the current position detection periods Tk and Ts for reading the displacement signal for performing camera shake correction are not limited to the values exemplified in the above embodiment, and the structure and mechanism 8 of the first and second actuators. It can be appropriately set according to the structure of

5 Camera module 11 Gyro IC
15 Image sensor 22 First actuator 34 Second actuator 50 Lens unit 62 System controller

Claims (12)

A camera shake detecting means for detecting a camera shake generated in the optical device and outputting a displacement signal corresponding to the camera shake displacement;
A current position detecting unit that detects a current position of a correcting unit that moves in a direction orthogonal to a photographing optical axis of the optical device and performs camera shake correction;
The displacement signal is read from the camera shake detection means at every sampling period, a target position for moving the correction means to eliminate camera shake is calculated based on the displacement signal, and the current position detection means is provided with a current position of the correction means. A camera shake control unit that detects a position for each current position detection cycle shorter than the sampling cycle, and moves the correction unit from the current position toward the target position;
A correction mode for switching between a first camera shake correction mode in which the sampling cycle is set to a first sampling cycle and a second camera shake correction mode in which a second sampling cycle is set to be longer than the first sampling cycle. A camera shake correction device comprising switching means.   The correction mode switching means sets the current position detection cycle to a first current position detection cycle in the first camera shake correction mode, and from the first current position detection cycle in the second camera shake correction mode. The camera shake correction apparatus according to claim 1, wherein the second current position detection cycle is set to be longer.   The correction mode switching means sets the movement speed of the correction means to the first movement speed in the first camera shake correction mode and is slower than the first movement speed in the second camera shake correction mode. The camera shake correction apparatus according to claim 2, wherein the movement speed is set to 2.   The camera shake correction apparatus according to claim 1, wherein the correction mode switching unit switches the camera shake correction mode according to an operation mode of the optical apparatus.   The correction mode switching means switches to the first camera shake correction mode when the operation mode of the optical device is a still image shooting mode, and the second camera shake correction mode when the operation mode is a movie shooting mode. The camera shake correction device according to claim 4, wherein   6. The camera shake correction apparatus according to claim 1, wherein the second sampling period is twice or more as long as the first sampling period. A first camera shake correction mode in which a sampling period for reading a displacement signal corresponding to a camera shake displacement from the camera shake detection means is set as a first sampling period, and a second sampling period that is longer than the first sampling period. Switching between two image stabilization modes,
Reading the displacement signal at every sampling period set in the step, and calculating a target position of a correction unit that moves in a direction orthogonal to the photographing optical axis and performs camera shake correction;
And causing the current position detection means to detect the current position of the correction means for each current position detection period shorter than the sampling period, and to move the correction means from the current position to the target position. To correct camera shake.   The current position detection cycle is set to a first current position detection cycle in the first camera shake correction mode, and a second current position longer than the first current position detection cycle in the second camera shake correction mode. The camera shake correction method according to claim 7, wherein the camera shake correction method is set to a detection cycle.   The movement speed of the correction means is set to the first movement speed in the first camera shake correction mode, and is set to a second movement speed that is slower than the first movement speed in the second camera shake correction mode. The camera shake correction method according to claim 8. In a camera module comprising 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 captures an optical image formed by the photographing optical system,
A camera module comprising the camera shake correction device according to claim 1, wherein the lens unit is moved as the correction unit.   The camera module according to claim 10, wherein the number of pixels of the image sensor is 5M pixels or more.   A mobile phone comprising the camera module according to claim 10.

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