JP2006220758A - Shake correction device, optical equipment, control method for shake correction device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To minimize, by a simple configuration, a decrease in an amount of peripheral light, which occurs due to the weight of a shake correction means. <P>SOLUTION: The shake correction device includes: a shake detection means 58; the shake correction means 12; an arithmetic means 46 for working out shake correction information for driving the shake correction means on the basis of shake detection information from the shake detection means; a position detecting means 60 for detecting a position; a storage means 48 pre-storing corresponding relations between the position information and correction information for correcting a decrease in an amount of peripheral light of an image; and shake correction control means 46 and 44 for acquiring gravity correction information from position information in actual use and the correction information for correcting the decrease in the amount of peripheral light, then correcting the shake correction information according to the gravity correction information, and driving the shake correction means according to the shake correction information corrected. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a shake correction apparatus, an optical apparatus, and a control method for a shake correction apparatus having a function of correcting a shake such as a camera shake.

  When an image is captured by a camera, image degradation may occur due to camera shake or camera shake (blurring). In order to prevent the image deterioration, a shake correction apparatus that optically corrects the shake has been developed. This type of shake correction apparatus includes a shake detection unit that includes an angular velocity sensor that detects shake, a shake correction calculation unit that includes an integrator that converts shake detection information into a drive position signal, and correction for correcting shake. It is comprised by the correction lens drive part which consists of the actuator which drives a lens, and a drive circuit. A vibration gyro sensor or the like is used as the angular velocity sensor. The output signal of the gyro sensor, which is speed information, can be converted into position information by integrating. By making the correction lens follow the position information, it is possible to realize a shake correction (anti-vibration) operation.

  In the above correction device, the correction lens for correcting the shake is supported in the lens barrel by a member such as a spring. Therefore, when the elastic force of the spring is weaker than the force due to the weight of the correction lens, a deviation occurs between the optical axis of the correction lens and the imaging surface, and as a result, the amount of light (luminance) drops only at the upper corner of the captured image. There is.

With regard to a drop in the amount of light in a captured image, it is known that the peripheral portion of a captured image is generated as a low-brightness image due to a drop in the amount of peripheral light in which the amount of light passing through the lens decreases toward the lens periphery. Conventionally, a method of correcting a pixel with a reduced light amount by image processing (Patent Document 1, Patent Document 2) or a method of correcting the aperture opening diameter (Patent Document 2) with respect to the problem of the peripheral light amount drop. Etc. have been proposed.
Japanese Patent Laid-Open No. 9-307789 JP 2001-275029 A Japanese Patent Laid-Open No. 11-286552

  However, since the elastic force of the spring is weaker than the force due to the weight of the correction lens, the problem that the amount of light falls only at the upper corner of the photographed image is provided with the techniques as described in the above proposals such as a shake correction device or the like. Would be expensive.

  On the other hand, the elasticity of the spring is made stronger than the force due to the weight of the correction lens so that the optical axis of the correction lens and the imaging surface (center of the image sensor) do not shift, and the amount of light at the upper corner of the captured image is reduced. Although it is conceivable to eliminate the problem, in this case, it is necessary to increase the driving force of the correction lens when correcting the blur, resulting in an increase in the size of the blur correction device and an increase in driving power. It is not preferable.

(Object of invention)
An object of the present invention is to provide a shake correction apparatus, an optical apparatus, and a control method for the shake correction apparatus that can reduce a peripheral light amount drop caused by the weight of the shake correction unit with a simple configuration.

  In order to achieve the above object, the invention described in claim 1 is based on blur detection means for detecting blur, blur correction means for correcting blur, and blur detection information from the blur detection means. A shake correction apparatus having calculation means for calculating shake correction information for driving the shake correction means, and an attitude detection means for detecting the attitude of the shake correction apparatus, for correcting a peripheral light amount drop in an image Gravity correction information is acquired from the storage means that stores the correspondence relationship between the correction information and the posture information in advance, the posture information at the time of actual use and the correction information for correcting peripheral fall, and the gravity correction information The shake correction apparatus includes a shake correction control unit that corrects the shake correction information and drives the shake correction unit based on the corrected shake correction information.

  In order to achieve the above object, the invention described in claim 2 is directed to an image pickup means, a shake detection means for detecting a shake, a shake correction means for correcting a shake, and a shake detection from the shake detection means. An optical device having calculation means for calculating shake correction information for driving the shake correction means based on information, and posture detection means for detecting the posture of the optical device, and is imaged by the imaging device Gravity correction information based on the correction information for correcting the peripheral light loss of the image and the correspondence information of the posture information in advance, the posture information at the time of actual use and the correction information for correcting the peripheral drop , The shake correction information is corrected by the gravity correction information, and the shake correction control means for driving the shake correction means is used.

  Similarly, in order to achieve the above object, the invention described in claim 3 includes a storage unit that stores in advance a correspondence relationship between correction information for correcting a peripheral light amount drop in an image and posture information for detecting the posture of a shake correction device. A method for controlling a shake correction apparatus, wherein gravity correction information is acquired from posture information in actual use and the correction information for correcting peripheral fall, and shake correction for driving the shake correction apparatus based on the gravity correction information The control method of the shake correction apparatus that corrects information and drives the shake correction means based on the corrected shake correction information.

  According to the present invention, it is possible to provide a shake correction device, an optical apparatus, or a control method for a shake correction device that can reduce a peripheral light amount drop due to the weight of the shake correction unit with a simple configuration.

  The best mode for carrying out the present invention is as shown in Example 1 and Example 2 described below.

  FIG. 1 is a block diagram showing a circuit configuration of a camera (imaging device) such as a digital camera according to Embodiment 1 of the present invention. Inside the lens barrel 10, there are a correction lens 12 for correcting camera shake and the like driven in the direction perpendicular to the optical axis by an actuator, a zoom lens 14 driven in the optical axis direction by a motor (not shown), It has a focus lens 16 and a shutter 18 having a diaphragm function. The imaging element 20 converts an optical image incident through the lens barrel 10 into an analog signal. The analog signal is converted into a digital signal by the A / D converter 28 and output to the subsequent stage. The timing generator 22 supplies a clock signal and a control signal to the image sensor 20, the D / A converter 24, and the A / D converter 28.

  An image display unit 26 constituted by a thin film transistor drive type liquid crystal display (TFT LCD) or the like is stored in an image display storage unit 32 input via the D / A conversion unit 24 under the control of the memory control unit 30. Display image data and so on. By sequentially displaying the captured image data on the image display unit 26, an electronic viewfinder function can be realized. The memory control unit 30 is controlled by the camera system control unit 46, and the data for the timing generator 22, the D / A conversion unit 24, the A / D conversion unit 28, the image display storage unit 32, and the image processing unit 34 described later. Perform input / output control. The image processing unit 34 performs predetermined pixel interpolation processing and color conversion processing on data from the A / D conversion unit 28 or the memory control unit 30.

  The camera system control unit 46 controls the lens barrel control unit 36, the exposure control unit 38, the distance measurement control unit 40, and the zoom control unit 42 according to the operation performed by the operation unit 56. The lens barrel control unit 36 drives the correction lens 12, the zoom lens 14, the focus lens 16, and the shutter 18 having an aperture function into a shootable state or a retracted state depending on the playback and shooting state of the camera. The exposure control unit 38 performs AE (automatic exposure) control by controlling the shutter 18 having an aperture function based on the information measured by the image processing unit 34. The distance measurement control unit 40 drives and controls the focus lens 16 based on the subject distance obtained by the image processing unit 34, and performs AF (autofocus) control and the like. The zoom control unit 42 drives and controls the zoom lens 14 according to the operation amount of an operation member such as a zoom lever or a zoom button of the operation unit 56. In addition, the camera system control unit 46 calculates a lens correction amount from the shake amount detected by the shake detection unit 58 that detects a shake such as a camera shake, and transmits the correction amount to the shake correction control unit 44. The shake correction control unit 44 can perform shake correction on a two-dimensional image by driving and controlling the correction lens 12 in two directions, the vertical direction and the horizontal direction. Further, the camera system control unit 46 acquires the posture information of the camera detected by the posture detection unit 60, and performs control so that an image is displayed in an optimal display direction during image reproduction.

  The memory 48 stores a work area of the camera system control unit 46, a volatile area used as a temporary storage area for captured still images and moving images, and a non-volatile area for storing design values necessary for driving the camera. There is. The storage capacity of the memory 48 is sufficient to store a predetermined number of still images and a moving image for a predetermined time. In the case of continuous shooting or panoramic shooting for continuously shooting a plurality of still images. In addition, high-speed and large-volume image writing is possible. The power source 50 includes a battery detection circuit, a DC-DC converter, and a switch circuit that switches a circuit block to be energized (not shown). The power source 50 detects the presence / absence of a battery, the type of battery, the remaining battery level, etc. The DC-DC converter is controlled on the basis of the detection result and an instruction from the camera system control unit 46, and a voltage and a current are supplied to each unit including the recording medium for a required period of a necessary power source.

  An interface (I / F) 52 is an interface with a recording medium such as a memory card or a hard disk. The recording unit 54 is for storing image data and the like on a recording medium, and can access the camera system control unit 46 via the interface 50.

  The posture detection unit 60 is configured by, for example, an inclination sensor that detects the direction of gravity. FIG. 2 illustrates an attitude detection unit 60 configured by an inclination sensor. As an operation principle, the detection member 60a and the ball member 60c that rolls on the detection member 60a, and the detection member 60b and the ball member 60c that rolls on the detection member 60b function as switches SW1 and SW2, respectively. The switches SW1 and SW2 are in the ON state when 60b and the ball member 60c are grounded, and the switches SW1 and SW2 are in the OFF state when not grounded. When the predetermined tilt is exceeded, the switch state changes, so that the tilt of the camera that is the object to be measured can be detected. For example, if the camera is in the horizontal orientation (normal position) as shown in FIG. 2B, both the switches SW1 and SW2 are turned on, and the camera orientation is vertical (the grip side is down). When the switch SW1 is turned on, the switch SW1 is turned on and the switch SW2 is turned off. If the camera is in the vertical orientation (grip side is up) opposite to the above, the switch SW1 is turned off and the switch SW2 is turned on. Therefore, the camera system control unit 46 can recognize the state of the switches SW1 and SW2 as camera posture information.

  FIG. 3 is a diagram illustrating a captured image in which a light amount (brightness) drop occurs in the upper corner of the captured image. FIG. 3A illustrates a case where the camera is photographed while holding the camera sideways, and FIG. A black spot region indicates a place where the amount of light that occurs when shooting is taken in the vertical direction.

  Here, the correction lens 12 is supported in the lens barrel 10 by an elastic member such as a spring. If the elasticity of the spring is made stronger than the force due to the weight of the correction lens 12, as described above, it is necessary to increase the driving force of the correction lens 12, which increases the size of the lens barrel 10 and further the camera. There is an inconvenience of inviting. For this reason, the elastic force of the spring is set to be weaker than the force due to the weight of the correction lens 12, and accordingly, the optical axis of the correction lens 12 and the imaging surface (specifically, the optical axis of the lens other than the correction lens (photographing optical axis)). 3), the light amount drops at the upper ends of the long side in the horizontal posture of the camera in FIG. 3A, and the upper ends of the short side in the vertical posture of the camera in FIG. 3B. The amount of light will fall.

  Next, in the camera having the above-described configuration, an operation at the time of camera shake correction (anti-shake) performed by the camera system control unit 46 will be described with reference to the flowchart of FIG.

  First, in step S101, the camera system control unit 46 detects shake angular velocity information detected by the shake detection unit 58. As the shake detection unit 58, for example, an angular velocity detection sensor such as a gyro sensor is used, and the analog output of the gyro sensor is quantized and sampled by the A / D conversion unit, and is then processed by the camera system control unit 46. Provided. In the next step S102, the phase compensation filter calculation is performed to compensate for the phase delay that occurs in the entire control system. In subsequent step S103, the angular velocity information is converted into position (displacement) information by low-pass filter integration calculation. In subsequent step S104, focal length information changed by the position of the zoom lens 14 that is driven and controlled by the zoom control unit 42 is acquired, and an appropriate gain (gain) is applied to the control amount (position information) of the correction lens 12. . The longer the focal length, the larger the blur correction control amount. Conversely, the shorter the focal length, the smaller the blur correction control amount. Thereby, the target planned lens position when the attitude of the camera is not taken into consideration can be obtained.

  In the next step S105, the gravity previously stored in the camera based on the camera posture information (state signals of the switches SW1 and SW2 shown in FIG. 2) and the offset b (described later) detected by the posture detector 60. A correction offset value is derived, and the target lens position is added to the gravity correction offset value to calculate a final lens drive target value considering the posture information. The offset b is correction information for correcting a peripheral light amount drop obtained by photographing a chart image having the same luminance in advance and calculating a luminance difference between the central portion of the image and a luminance portion of the peripheral portion from the acquired luminance data. A table indicating correspondence with camera posture information (corresponding to posture gain described later) is stored in a nonvolatile area of the memory 48. The gravity correction offset value is information derived from this table based on the posture information of the camera in actual use. In the next step S106, the lens drive target value obtained by adding the target lens position to the gravity correction offset value is used as the control input of the shake correction control unit 44. In the next step S107, the shake correction control unit 44 corrects the lens drive target value. The lens 12 is driven. As a result, the blur correction control unit 44 performs drive control of the correction lens 12 as will be described later with reference to FIG. 5. As a result, blur correction including the weight of the correction lens 12 is performed, and the upper portion shown in FIG. A photographed image can be obtained with no light loss at the corners.

  In the next step S108, it is determined whether or not the state of continuing the shake correction (anti-vibration) operation is set, for example, by confirming the state of the operation unit 56. If the state is set to continue, the process proceeds to step S101. Return and repeat the same operation as above. If the shake correction operation is in a state to end, the shake correction operation is ended.

  FIG. 5 is a block diagram showing a control system of the shake correction control unit 44. In the figure, the target lens position a is obtained by the processing of steps S101 to S104 in FIG. 5, and the offset b is for correcting the peripheral light amount drop measured in advance as described above. The camera posture is not considered (in other words, the optical axis deviation due to the weight of the correction lens 12 is not considered), and the gravity correction offset value c is expressed by (offset b) × (posture gain). The obtained gravity correction information in consideration of the posture of the camera, and the lens drive target value d is information obtained by (target planned lens position a) + (offset d) × (posture gain). Then, the lens drive target value d becomes a control input of the shake correction control unit 44. The gravity correction offset value c is a table stored in advance in the memory 48 indicating the correspondence between information (offset b) and posture information (posture gain) for correcting the peripheral light amount drop as described above. FIG. 5 schematically shows information obtained by (offset b) × (posture gain).

  The shake correction control unit 44 controls the correction lens 12 that is the control target 214 with the control amount e derived according to the control gain 212. The control gain 212 is a gain based on a control method such as PID control (proportional / differential / integral control), for example. The current position of the correction lens 12 that is drive-controlled, that is, the control lens position f is measured by a position sensor such as a Hall element. The position correction gain 216 is applied to the control lens position f and the shake correction control unit. Feedback to 44 control inputs. The position detection gain 216 is a gain that determines the measurement range of the position sensor. At this time, the position detection gain 216 needs to set a gain at which the detection position can be linear with respect to the control amount e within the measurement range.

  Here, for example, when the posture detection unit 60 detects that the camera is in the horizontal direction (normal position), one of the horizontal (left and right) driving control of the correction lens 12 in the vertical direction and the horizontal direction is performed. The orientation gain 210 in the direction control system is 0, and the control input at this time is only information on the target planned lens position a, and normal blur correction control is performed. On the other hand, the attitude gain in the control system in the vertical (vertical) direction is 1, and the control input at this time is (target planned lens position a + gravity correction offset value c), and the control amount e is equivalent to the gravity correction offset value c. The blur correction control unit 44 performs control to push the correction lens 12 upward. This corrects a drop in the amount of peripheral light generated at the top.

  Similarly, even when the camera is tilted vertically with the grip down or up, the control amount e is increased in the direction opposite to the gravitational direction to compensate for the loss of peripheral light regardless of the camera posture. It becomes possible to do.

  According to the first embodiment, the correspondence relationship between the correction information (offset b) and the camera posture information (posture gain) for correcting the peripheral light amount drop in the captured image is stored in the camera in advance, and At the time of use, the posture information of the camera at that time is detected, gravity correction information (gravity correction offset value c) obtained from the posture information is obtained, and the gravity correction information is calculated from information from the shake detection unit 58. The shake correction control amount (target planned lens position a) of the correction lens 12 is changed (correction is added).

  Therefore, without providing a conventional expensive and complicated circuit for correcting the peripheral light loss, the optical axis shift (the center of the correction lens 12 and the image sensor 20) caused by the weight of the correction lens 12 can be achieved with a simple configuration. It is possible to appropriately correct the deviation of the optical axis) and reduce the amount of peripheral light in the captured image. Furthermore, even when the camera is in the horizontal position, even if the grip is in the vertical direction with the grip down or up, the optical axis deviation between the correction lens 12 and the center of the image sensor 20 can be corrected appropriately. Thus, it is possible to reduce the decrease in the amount of peripheral light in the captured image regardless of the posture of the camera.

  Next, a camera according to Embodiment 2 of the present invention will be described. Since the circuit configuration of the camera is the same as that in FIG. 1, the description thereof is omitted.

  FIG. 6 is a block diagram showing a control system of the shake correction control unit 44 provided in the camera according to Embodiment 2 of the present invention.

  In the first embodiment, the gravity correction information (offset b × posture gain) obtained from the posture information and the information for correcting the peripheral light amount drop is added to the target planned lens position a, and this is added to the shake correction control unit 44. As a control input. On the other hand, in the second embodiment of the present invention, as shown in FIG. 6, the gravity correction offset value c is input to the position detection system which is the feedback input of the shake correction control unit 44, and the gravity correction is performed from the signal of the position detection system. The offset value c is subtracted. Also in this configuration, it is possible to derive the control amount e similar to that in the first embodiment.

  FIG. 7 is a flowchart showing an operation at the time of shake correction (anti-vibration) in the camera system control unit 46 according to the second embodiment of the present invention when the control system shown in FIG. 6 is used.

  The camera system control unit 46 first detects shake angular velocity information detected by the shake detection unit 58 in step S201. In the next step S202, the phase delay generated in the entire control system is compensated by performing the phase compensation filter calculation. In subsequent step S203, the angular velocity information is converted into position (displacement) information by low-pass filter integration calculation. In subsequent step S204, focal length information changed by the position of the zoom lens 14 that is driven and controlled by the zoom control unit 42 is acquired, and an appropriate gain (gain) is applied to the control amount (position information) of the correction lens 12. . Thereby, the target planned lens position a when the posture of the camera is not taken into consideration is obtained. The information of the target planned lens position a is set as one control input of the shake correction control unit 44.

  In the next step S205, the gravity correction offset value stored in the camera in advance based on the camera posture information (state signals of the switches SW1 and SW2 shown in FIG. 2) detected by the posture detector 60 and the offset b. c is derived, and this gravity correction offset value c is set as one of the control inputs of the shake correction control unit 44. As a result, an operation (target planned lens position a− (position detection system signal−gravity correction offset value c)) as shown in FIG. 6 is performed in the shake correction control unit 44, and the final operation in consideration of the posture information is performed. A driving target value of the correction lens 12 is calculated. In this case, the offset b is the same as in the first embodiment, in which a chart image having the same luminance is captured in advance, and the peripheral light amount drop obtained by calculating the luminance difference between the central portion and the peripheral portion from the acquired luminance data. A table indicating the correspondence with camera posture information (corresponding to posture gain) is stored in a non-volatile area of the memory 48. The gravity correction offset value c is information derived from this table based on the posture information of the camera in actual use. In step S206, the blur correction control unit 44 drives the correction lens 12. As a result, the drive control of the correction lens 12 is performed by the shake correction control unit 44. As a result, the shake correction including the weight of the correction lens 12 is performed, and the photographed image with no light loss at the upper corner shown in FIG. Can be obtained.

  In the next step S207, it is determined whether or not the state of continuing the shake correction (anti-vibration) operation is set, for example, by checking the state of the operation unit 56. If the state is set to continue, the process proceeds to step S201. Return and repeat the same operation as above. If the shake correction operation is in a state to end, the shake correction operation is ended.

  According to the second embodiment, as in the first embodiment, the correspondence relationship between the correction information (offset b) and the camera posture information (posture gain) is stored in the camera in advance in order to correct the peripheral light amount drop in the captured image. When the camera is actually used, the posture information of the camera at that time is detected, gravity correction information obtained from the posture information is obtained, and the correction lens 12 calculated based on the shake detection information by the gravity correction information. The blur correction control amount (target planned lens position a) is changed.

  Therefore, without providing a conventional expensive and complicated circuit for correcting the peripheral light loss, the optical axis shift (the center of the correction lens 12 and the image sensor 20) caused by the weight of the correction lens 12 can be achieved with a simple configuration. It is possible to appropriately correct the deviation of the optical axis) and reduce the amount of peripheral light in the captured image. Furthermore, even when the camera is in the horizontal position, even if the grip is in the vertical direction with the grip down or up, the optical axis deviation between the correction lens 12 and the center of the image sensor 20 can be corrected appropriately. Thus, it is possible to reduce the decrease in the amount of peripheral light in the captured image regardless of the posture of the camera.

  The present invention is suitable for an imaging apparatus such as a digital camera including a card type. Furthermore, it is also suitable for an optical device such as a mobile phone with a built-in photographing function.

It is a block diagram which shows the circuit structure of the camera concerning each Example of this invention. It is a figure explaining the inclination sensor which is an example as an attitude | position detection part of FIG. It is a figure explaining the difference of the peripheral light amount fall which arises with a camera attitude | position. It is a flowchart which shows the blurring correction | amendment operation | movement in Example 1 of this invention. It is a block diagram of the shake correction control part in Example 1 of the present invention. It is a block diagram of the shake correction control part in Example 2 of this invention. It is a flowchart which shows the blurring correction | amendment operation | movement in Example 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 12 Correction lens 20 Image pick-up element 26 Image display part 30 Memory control part 42 Zoom control part 44 Shake correction control part (blur correction control means)
46 Camera system control unit (calculation means, shake correction control means)
48 memory (memory means)
56 Operation section 58 Shake detection section (blur detection means)
60 Posture detection unit (posture detection means)

Claims (3)

Blur detection means for detecting blur;
Blur correction means for correcting blur;
Calculation means for calculating shake correction information for driving the shake correction means based on shake detection information from the shake detection means;
Posture detection means for detecting the posture of the shake correction device;
A shake correction device comprising:
Storage means for preliminarily storing the correspondence between the correction information for correcting the peripheral light loss of the image and the posture information;
Gravity correction information is acquired from the posture information in actual use and the correction information for correcting peripheral fall, the shake correction information is corrected by the gravity correction information, and the shake correction unit is corrected by the corrected shake correction information. Blur correction control means for driving
A shake correction apparatus comprising: Imaging means;
Blur detection means for detecting blur;
Blur correction means for correcting blur;
Calculation means for calculating shake correction information for driving the shake correction means based on shake detection information from the shake detection means;
Attitude detection means for detecting the attitude of the optical device;
An optical instrument comprising:
Storage means for storing in advance a correspondence relationship between correction information for correcting a decrease in peripheral light amount of an image captured by the image sensor and the posture information;
Gravity correction information is acquired from the posture information in actual use and the correction information for correcting peripheral fall, the blur correction information is corrected by the gravity correction information, and the shake correction control unit drives the shake correction unit. When,
An optical apparatus comprising: A method for controlling a shake correction apparatus having storage means that stores in advance a correspondence relationship between correction information for correcting a peripheral light amount drop in an image and attitude information for detecting the attitude of the shake correction apparatus,
Gravity correction information is acquired from the posture information in actual use and the correction information for correcting peripheral fall, and the shake correction information for driving the shake correction device is corrected based on the gravity correction information, and the corrected shake correction is performed. A control method for a shake correction apparatus, wherein the shake correction means is driven by information.

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