JP2013113962A - Imaging device with shake correction function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging device with a shake correction function capable of reducing a correction residual error at the peripheral of an image even when shake correction is performed by using a shift system.SOLUTION: An imaging device 100 with a shake correction function includes an imaging optical system 1, an imaging element 2 arranged on the optical axis L of the imaging optical system 1, an image processing unit 3 that creates image data on the basis of imaging data provided by the imaging element 2, and shake correction means 4 for shifting an imaging area in a direction orthogonal to the optical axis L to correct shake of an image. The imaging optical system 1 uses an fθ optical system, and the image processing unit 3 creates image data of the fθ system as image data of the imaging area.

Description

  The present invention relates to an imaging apparatus with a shake correction function, such as a digital camera or a mobile phone with a camera.

  An imaging apparatus such as a digital camera or a camera-equipped mobile phone is configured as an imaging apparatus with a shake correction function having a shake correction function in order to suppress disturbance of a captured image due to a shake such as a user's hand shake. More specifically, in the imaging apparatus with a shake correction function, based on the shake detection result, movement in the direction orthogonal to the optical axis of the imaging optical system, movement in the direction orthogonal to the optical axis of the imaging element, image Shift-type shake correction using movement of image data generated by the processing unit in a direction orthogonal to the optical axis is performed (for example, see Patent Document 1).

  On the other hand, in the imaging apparatus, when the focal length of the imaging optical system is f, the angle formed by the object height and the optical axis of the imaging optical system is θw [radian], and the image height is H An ftan θ optical system in which the image height H is f · tan θw is used. According to such an optical system of the ftan θ system, an image height proportional to the object height can be obtained for an object at the same subject distance. For this reason, if a square cell is photographed, the square cell can be faithfully reproduced as an image, and thus there is an advantage of excellent imaging performance.

JP 2011-64870 A

  However, while the shake changes in the angular direction, the shake correction by the shift method uses a shift in a direction orthogonal to the optical axis, so that distortion occurs in the image after shake correction. It cannot be prevented. In particular, when an ftan θ-type optical system is used as the imaging optical system, a shift is made so as to correct an image shift at the center of the image (lens optical axis center), resulting in a peripheral portion of the image (region having a large image height). However, there is a problem that a large correction residual remains because the amount of image shift is greatly different from that near the center.

More specifically, it is as follows. First, as shown in FIG. 4A, when the object distance is S, the object height y, the angle between the object height and the optical axis is θw, the image distance is S ′, and the image height is h, The relationship holds.
Object height y = S · tan θw Equation (1)
Image height h = S ′ · tan θw Equation (2)

Here, as shown in FIG. 4B, when the camera shake angle is θ, the image position hc1 of the central object and the position hm1 of the image height corresponding to the object height y are based on the center of the image sensor. Is expressed as follows.
hc1 = S'.tan.theta .. Equation (3)
hm1 = S ′ · tan (θw + θ) (4)

Next, when camera shake correction is performed as shown in FIG. 4C, the image shift amount due to camera shake correction is hc1 itself because it is the center image blur correction. Therefore, after the camera shake correction, the position hc2 of the image height of the central object and the position hm2 of the image height corresponding to the object height y are expressed by the following equations with reference to the center of the image sensor.
hc2 = hc1−hc1 = 0 ・ ・ Expression (5)
hm2 = hm1-hc1 = S'.tan (.theta.w + .theta.)-S'.tan.theta. (6)

  Therefore, the image height position hm2 corresponding to the object height y after the camera shake correction is different from the image height h = S ′ · tan θw when there is no camera shake, and this difference becomes a correction residual.

For example, the focal length f is 4.00 mm, the opening diameter D is 1.43 mm, the opening radius R is 0.72 mm, the F value FNo (f / D) is 2.8, NA (R / f) is 0.18, If θw is 30 ° and θ is 1 °, the following results are obtained.
h = -2.309mm
θw + θ = 31.00 °
hc1 = -0.070mm
hm1 = -2.403mm
Shift amount = 0.070 mm
hc2 = 0
hm2 = -2.334 mm
Change rate of image height before and after shake correction = 1.049%

  As described above, when shake correction is performed using the shift method, a large correction residual remains in the peripheral portion of the image. For this reason, when the shift method is adopted, it is accepted that the influence of the correction residual in the peripheral part is unavoidable, and that the amount of camera shake correction is reduced to reduce the influence of the correction residual in the peripheral part (above In order to reduce the influence of the correction residual in the peripheral part, it is necessary to cope with reducing the maximum angle of view (corresponding to reducing θw in the above expression), etc. It is impossible to realize an imaging apparatus with a camera shake correction function that has a large angle of view and has a large camera shake correction angle and that does not generate a correction residual.

  In view of the above problems, an object of the present invention is to provide an imaging apparatus with a shake correction function that can reduce a correction residual in a peripheral portion of an image even when shake correction is performed using a shift method. It is to provide.

  In order to solve the above-described problems, the present invention provides an image pickup optical system, an image pickup element disposed on the optical axis of the image pickup optical system, and image processing for generating image data based on the image pickup data of the image pickup element. And a shake correction unit having a shake correction function that performs shake correction by shifting the imaging region in a direction orthogonal to the optical axis, wherein the image processing unit includes image data of the imaging region. As described above, fθ system image data is generated.

  In the present invention, the image processing unit generates fθ system image data as the image data of the imaging region, and the fθ system image data uses the shift method to center the image when the shake occurs. When the correction is made, the peripheral portion is also corrected at the same time. Therefore, even when shake correction is performed using the shift method, the correction residual at the periphery of the image can be reduced. Therefore, an imaging apparatus with a camera shake correction function having a large camera shake correction angle and a small correction residual can be realized with an imaging apparatus having a large angle of view.

  In the present invention, a configuration using an fθ optical system can be adopted as the imaging optical system. According to this configuration, the image processing unit can easily generate fθ-based image data as the image data of the imaging region.

  In the present invention, an fθ system optical system other than a complete fθ system is used as the imaging optical system, and the image processing unit obtains fθ system imaging data as the imaging data, and then coordinates the imaging data. Conversion may be performed to generate fθ-based image data as the image data of the imaging region. According to this configuration, even when a complete fθ optical system is not used as the imaging optical system, the same result as that obtained when a complete fθ optical system is used can be obtained by image processing.

  In the present invention, an optical system other than the fθ system is used as the imaging optical system, and the image processing unit obtains imaging data other than the fθ system as the imaging data, and then coordinates-converts the imaging data. As the image data of the imaging region, fθ-based image data may be generated. According to such a configuration, for example, when shake correction is not performed, ftan θ system image data is generated as image data, and only when shake correction is performed, fθ system image data is generated as image data. The configuration can be adopted.

  In the present invention, the image processing unit may further perform coordinate conversion of fθ system image data and output ftan θ system display data after shake correction processing. According to this configuration, the object can be faithfully reproduced as an image while eliminating the correction residual.

  In the present invention, the shake correction unit is configured to move the imaging optical system in a direction perpendicular to the optical axis, move the imaging element in a direction perpendicular to the optical axis, based on a shake detection result, and Adopting a configuration in which the imaging region is shifted in a direction orthogonal to the optical axis by at least one of the movements of the image data generated by the image processing unit in a direction orthogonal to the optical axis. it can. According to such a configuration, the configuration can be simplified as compared with the swing method in which the shake correction is performed by swinging the imaging optical system and the imaging element.

  In the present invention, the image processing unit generates fθ system image data as the image data of the imaging region, and the fθ system image data uses the shift method to center the image when the shake occurs. When the correction is made, the peripheral portion is also corrected. Therefore, even when shake correction is performed using the shift method, the correction residual at the periphery of the image can be reduced. Therefore, an imaging apparatus with a camera shake correction function having a large camera shake correction angle and a small correction residual can be realized with an imaging apparatus having a large angle of view.

It is explanatory drawing of the apparatus carrying the imaging device with a shake correction function which concerns on Embodiment 1 of this invention. It is explanatory drawing which shows the influence of camera-shake correction in the imaging device with a camera-shake correction function which concerns on Embodiment 1 of this invention. In this invention, it is explanatory drawing which shows the relationship between the object height and image height within the range defined as f (theta) system. It is explanatory drawing which shows the influence of camera-shake correction in the conventional imaging device with a camera-shake correction function.

  The best mode for carrying out the present invention will be described below with reference to the drawings. In the following description, the three directions orthogonal to each other are defined as an X axis, a Y axis, and a Z axis, respectively, and a direction along the optical axis is defined as a Z axis. Further, in the following description, among the shakes in each direction, rotation around the X axis corresponds to so-called pitching (pitch), rotation around the Y axis corresponds to so-called yawing (roll), and Z axis The rotation around corresponds to so-called rolling. Also, + X is attached to one side of the X axis, -X is attached to the other side, + Y is attached to one side of the Y axis, -Y is attached to the other side, and one side of the Z axis is attached. The side (opposite to the subject side) is marked with + Z, and the other side (subject side) is marked with -Z.

[Embodiment 1]
(overall structure)
FIG. 1 is an explanatory diagram of an apparatus equipped with an image pickup apparatus with a shake correction function according to Embodiment 1 of the present invention. FIGS. 1 (a) and 1 (b) are explanatory diagrams of camera shake and a method for shifting camera shake. It is explanatory drawing which shows a mode that it correct | amends by.

  An imaging apparatus 100 with a shake correction function shown in FIG. 1 is mounted on an optical device 1000 such as a digital camera or a camera-equipped mobile phone. In the optical apparatus 1000, the imaging apparatus 100 with a shake correction function includes image data based on the imaging optical system 1, the imaging element 2 disposed on the optical axis L of the imaging optical system, and imaging data obtained by the imaging element 2. The image processing unit 3 outputs the generated image data as image data to a recording device or the like provided in the optical device 1000.

  In addition, in the optical device 1000, when a shake such as a hand shake such as pitching or yawing occurs during shooting, the captured image is disturbed. Therefore, in the imaging apparatus 100 with a shake correction function of the present embodiment, the shake that performs shake correction by the shift method based on the detection result by the shake detection sensor such as a gyroscope or the monitoring result of the image change in the image processing unit 3 or the like. Correction means 4 is provided. In this embodiment, the shake correction unit 4 moves in the direction orthogonal to the optical axis L of the imaging optical system 1 based on the detection result of the shake (see the solid line S1 in FIG. 1B), and the light of the imaging device 2. Movement in the direction orthogonal to the axis L (see the dashed line S2 in FIG. 1B), and movement in the direction orthogonal to the optical axis L of the image data generated by the image processing unit 3 (in FIG. 1B) By moving at least one of the two-dot chain line S3), the imaging target region is shifted in the direction orthogonal to the optical axis L, and the influence of shake on the image data is prevented. With respect to the shift amount at that time, the present invention can be applied to either feedback control or open control.

  Hereinafter, the features and the like of the present embodiment will be described by taking as an example a case where the shake correction unit 4 moves the imaging optical system 1 in a direction orthogonal to the optical axis L based on the shake detection result. Even when a configuration in which the image sensor 2 is moved in a direction orthogonal to the optical axis L or a configuration in which the image data generated by the image processing unit 3 is moved in a direction orthogonal to the optical axis L is applied. be able to.

(Definition of fθ system)
FIG. 2 is an explanatory diagram illustrating the influence of camera shake correction in the imaging apparatus with a camera shake correction function according to the first embodiment of the present invention. FIGS. 2A, 2B, and 2C show camera shake. It is explanatory drawing which shows the previous state, explanatory drawing which shows the state which camera shake generate | occur | produced, and explanatory drawing which shows the state after correcting camera shake. FIG. 3 is an explanatory diagram showing the relationship between the object height and the image height within the range defined as the fθ system in the present invention.

In this embodiment, the image processing unit 3 generates fθ system image data as image data after shake correction. More specifically, in this embodiment, an fθ optical system is used as the imaging optical system 1. Here, the optical system of the fθ system need not be a complete fθ system, but may be any optical system that is close to the fθ system as viewed from the ftanθ system. That is, in the case of a complete fθ system, the following expression is satisfied.
H = f · θw
f = focal length of imaging optical system H = image height θw = angle formed by object height and optical axis [radians]
However, in this embodiment, even when the following expression is satisfied, it is defined as an fθ system.
abs (H− (f · θw)) ≦ abs (H− (f · tan θw)) Equation (7)
abs = calculation of absolute value

  More strictly, the configuration in the range corresponding to ± 1/2 of the difference between the conditions of the complete fθ system and the conditions of the complete ftan θ system is defined as the fθ system compared with the case where the complete fθ system is used. To do. Such conditions can be expressed by the following equation.

In the case of a complete ftan θ system, as described with reference to FIG. 4, the object distance is S, the object height is y, the angle between the object height and the optical axis is θw, the image distance is S ′, and the image height. Where h is the following relationship.
Object height y = S · tan θw Equation (8)
Image height h = S ′ · tan θw Equation (9)
From Equation (8) and Equation (9),
h = (S ′ / S) · y (10)

On the other hand, in the case of a complete fθ system, as shown in FIG. 2, the object distance is S, the object height is Y, the angle between the object height and the optical axis is θw, the image distance is S ′, and the image height. If H is H, the following relationship is established.
Object height Y = S · tan θw Equation (11)
Image height H = S '· θw ··· Formula (12)
From Equation (11) and Equation (12),
H = S ′ · tan ⁻¹ (Y / S)... (13)

The object height y and Y are the same.
Therefore,
In the present invention, the range corresponding to H ± ((h−H) / 2) is defined as the fθ system when expressed using h and H calculated by Expression (10) and Expression (13).

  When such a range is set, the object height and the image height are expressed as shown in FIG. In FIG. 3, a solid line L0 indicates the relationship between the object height and the image height in the case of the complete ftan θ system, and a solid line L1 indicates the relationship between the object height and the image height in the case of the complete fθ system, and the solid line L11. Indicates the relationship between the object height and the image height at the upper limit of the fθ system, and the solid line L12 indicates the relationship between the object height and the image height at the lower limit of the fθ system.

  Therefore, the “fθ system” in the present invention means a configuration that satisfies the condition range sandwiched between the solid line L11 and the solid line L12. Further, the “complete fθ system” means a configuration that satisfies the condition indicated by the solid line L1. Therefore, “an fθ system other than a perfect fθ system” means a configuration excluding a configuration satisfying the condition range indicated by the solid line L11 among the configurations satisfying the condition range sandwiched between the solid line L11 and the solid line L12. On the other hand, “other than the fθ system” means a configuration that does not satisfy the condition range between the solid line L11 and the solid line L12.

(Correction residual during camera shake correction)
In the imaging apparatus 100 with the shake correction function of the present embodiment, since the fθ optical system is used as the imaging optical system 1, the center of the image is corrected using the shift direction during the camera shake correction as described below. In this case, the peripheral portion of the image is also corrected at the same time. Therefore, even when shake correction is performed using the shift method, the correction residual at the periphery of the image can be reduced.
In the following description, a case where a complete fθ optical system indicated by a solid line L1 in FIG. 3 is used will be described for easy understanding of the principle.

First, in this embodiment, since the fθ optical system is used as the imaging optical system 1, as shown in FIG. 2A, the object distance is S, the object height is Y, the object height and the optical axis. When the angle is θw, the image distance is S ′, and the image height is H, the following relationship is established.
Object height Y = S · tan θw Equation (14)
Image height H = S '· θw ··· Equation (15)

  In such an fθ optical system, image distortion (distortion aberration, distortion) is larger in the peripheral part than in the central part, compared to the case where the ftan θ optical system is used. When the angle θw is 35 °, the distortion of the image height is about −13%.

Here, as shown in FIG. 2B, when the camera shake angle is θ, the image position Hc1 of the central object and the position Hm1 of the image height corresponding to the object height y are based on the center of the image sensor 2. Then, the following equation is obtained.
Hc1 = S '· θ Equation (16)
Hm1 = S ′ (θw + θ) Equation (17)

Next, when camera shake correction is performed as shown in FIG. 2C, the image shift amount due to camera shake correction is Hc1 itself because it is the center image blur correction. Accordingly, the position Hc2 of the elephant height of the central object and the position Hm2 of the image height corresponding to the object height Y after the camera shake correction are expressed by the following formulas based on the center of the image sensor.
Hc2 = Hc1−Hc1 = 0 ../ Expression (18)
Hm2 = Hm1−Hc1 = S ′ · (θw + θ) −S ′ · θ = S ′ · θw (19)
Therefore, the image height position Hm2 corresponding to the object height Y after the camera shake correction is equal to the image height H = S ′ · θw when there is no camera shake, and no correction residual is generated.

For example, the focal length f is 4.00 mm, the opening diameter D is 1.43 mm, the opening radius R is 0.72 mm, the F value FNo (f / D) is 2.8, NA (R / f) is 0.18, When θw is 30 ° and θ is 1 °, the following results are obtained. Even when shake correction is performed using the shift method, no correction residual remains in the peripheral portion of the image.
H = -2.094mm
θw + θ = 31.00 °
Hc1 = -0.070mm
Hm1 = −2.164
Shift amount = 0.070 mm
Hc2 = 0
Hm2 = −2.094
Change rate of image height before and after shake correction = 0%

  Even when θw is an angle other than 30 °, the rate of change of the image height before and after shake correction is 0%. Further, in place of the complete fθ system optical system shown by the solid line L1 in FIG. 3, when an fθ optical system other than the complete fθ system shown by the solid lines L11 and L12 in FIG. Even when shake correction is performed using this method, the correction residual is small at the periphery of the image.

(Main effects of this form)
As described above, in the present embodiment, the shake correction based on the shift method is employed, and since the fθ optical system is used as the imaging optical system 1, the peripheral portion of the image is different from the case where the ftan θ optical system is used. Then, there is no correction residual or the correction residual is extremely small. Therefore, according to the present embodiment, it is not necessary to accept that the influence of the correction residual in the peripheral portion is unavoidable, and it is possible to reduce the camera shake correction amount in order to reduce the influence of the correction residual in the peripheral portion (in the above formula, There is no need for a response to reduce θ), a response to reduce the maximum angle of view in order to reduce the influence of the correction residual in the peripheral portion (a response to reduce θw in the above equation), or the like. Therefore, it is possible to realize the imaging apparatus 100 with a camera shake correction function that has a large camera shake correction angle and a small correction residual with an imaging apparatus having a large angle of view.

  In this embodiment, since an fθ optical system is used as the imaging optical system 1, fθ system image data is used as image data of the imaging region without performing processing such as coordinate conversion in the image processing unit 3. The correction residual can be generated at the periphery of the image, or the correction residual is extremely small.

[Embodiment 2]
In the first embodiment, an fθ optical system is used as the imaging optical system 1. However, when an optical system other than the fθ system is used as the imaging optical system 1, for example, an ftan θ optical system is used as the imaging optical system 1. Is used, the image processing unit 3 obtains ftan θ-based imaging data as imaging data from the imaging device 2, and then coordinates-transforms the imaging data to generate fθ-based image data as image data of the imaging region. May be.

  In this case, fθ system image data may be generated as image data at all times. When shake correction is not performed, only when ftan θ system image data is generated and shake correction is performed. The image data may be configured to generate fθ system image data.

[Embodiment 3]
In the first embodiment, an fθ optical system is used as the imaging optical system 1 and the fθ system image data is generated without performing coordinate conversion in the image processing unit 3. In addition, an fθ system optical system that is not an fθ system is used, and the image processing unit 3 performs coordinate conversion of the imaging data output from the imaging device 2 to generate fθ system image data as image data of the imaging region. May be. According to such a configuration, instead of the complete fθ optical system indicated by the solid line L1 in FIG. 3, an fθ optical system other than the complete fθ system indicated by the solid lines L11 and L12 in FIG. 3 is used. However, it is possible to employ a configuration in which no correction residual remains in the peripheral portion of the image.

[Embodiment 4]
In the first to third embodiments, the shake correction is performed using the fθ image data generated by the image processing unit 3 and the fθ image data is used as display data. After the correction, the fθ system image data may be transformed to generate ftan θ system display data, and the ftan θ system display data may be output. According to such a configuration, when shake correction is performed on θ-system image data, there is no correction residual at the periphery of the image, or the correction residual is small. For this reason, if the fθ system image data is generated by performing coordinate conversion after the shake correction to generate the ftan θ system display data, the peripheral portion of the fθ system image is distorted with respect to the vicinity of the center and the appearance is good. It is possible to make a configuration in which no correction residual is left in the peripheral portion of the image or a configuration in which the correction residual is small while eliminating the disadvantage of being absent. Also, whether to use fθ system image data generated in the image processing unit 3 as display data or ftan θ system display data obtained by coordinate conversion of fθ system image data, depending on the imaging target, imaging conditions, and the like. You may comprise so that switching is possible.

[Other embodiments]
The optical unit 100 with a shake correction function to which the present invention is applied is fixed in a device having vibration at regular intervals, such as a refrigerator, in addition to a mobile phone, a digital camera, etc. For example, when shopping, it can also be used for a service that can obtain information inside the refrigerator. In such a service, since it is a camera system with a posture stabilization device, a stable image can be transmitted even if the refrigerator vibrates. Further, the present apparatus may be fixed to a device worn at the time of attending school, such as a student's bag, a student's bag, a school bag, or a hat. In this case, when the surroundings are photographed at regular intervals and the image is transferred to a predetermined server, the guardian or the like can observe the image in a remote place to ensure the safety of the child. In such an application, a clear image can be taken even if there is vibration during movement without being aware of the camera. If a GPS is installed in addition to the camera module, the location of the target person can be acquired at the same time. In the event of an accident, the location and situation can be confirmed instantly. Furthermore, if the optical unit 100 with a shake correction function to which the present invention is applied is mounted at a position where the front can be photographed in an automobile, it can be used as a drive recorder. In addition, the image pickup apparatus 100 with a shake correction function to which the present invention is applied is mounted at a position where the front of the vehicle can be photographed, and peripheral images are automatically photographed at regular intervals and automatically transferred to a predetermined server. May be. Further, by distributing this image in conjunction with traffic jam information such as a car navigation road traffic information communication system, the traffic jam status can be provided in more detail. According to such a service, the situation at the time of an accident or the like can be recorded unintentionally by a third party who has passed unintentionally as well as a drive recorder mounted on a car, and can be used for inspection of the situation. In addition, a clear image can be acquired without being affected by the vibration of the automobile. In such an application, when the power is turned on, a command signal is output to the control unit, and shake control is started based on the command signal.

DESCRIPTION OF SYMBOLS 1 Imaging optical system 2 Imaging element 3 Image processing part 4 Shake correction means 100 Imaging device 1000 with shake correction function Optical apparatus

Claims (6)

An imaging optical system, an imaging device disposed on the optical axis of the imaging optical system, an image processing unit that generates image data based on imaging data of the imaging device, and an imaging region orthogonal to the optical axis An image pickup apparatus with a shake correction function having shake correction means for performing shake correction by shifting in a direction,
The image processing unit generates an image data of an fθ system as image data of the imaging region, and an imaging apparatus with a shake correction function.   The imaging apparatus with a shake correction function according to claim 1, wherein an fθ system optical system is used as the imaging optical system. As the imaging optical system, an fθ system optical system other than a complete fθ system is used,
The image processing unit acquires fθ imaging data as the imaging data, and then performs coordinate conversion of the imaging data to generate fθ image data as image data of the imaging region. The imaging apparatus with a shake correction function according to claim 1. An optical system other than the fθ system is used as the imaging optical system,
The image processing unit obtains imaging data other than the fθ system as the imaging data, and then performs coordinate conversion on the imaging data to generate fθ system image data as the image data of the imaging region. The imaging apparatus with a shake correction function according to claim 1.   5. The image processing unit according to claim 1, wherein the image processing unit further performs coordinate conversion of the fθ system image data and outputs ftan θ system display data after the shake correction process. 6. An imaging apparatus with a shake correction function described in 1.   The shake correction unit is configured to move the imaging optical system in a direction perpendicular to the optical axis, move the imaging element in a direction perpendicular to the optical axis, and the image processing unit based on a shake detection result. 5. The imaging region is shifted in a direction orthogonal to the optical axis by at least one of the movements of the image data generated in step S in a direction orthogonal to the optical axis. An imaging apparatus with a shake correction function according to any one of the above.

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