JP2006191202A - Dust detection apparatus, imaging apparatus, dust detection method and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging apparatus or the like, which obtain a beautiful image less affected by dust even when the dust exists on cover glass or the like located on an optical path between an imaging element and a photographing optical system. <P>SOLUTION: The imaging apparatus allows the imaging element 20 to carry out photographing operations for a plurality of number of times synchronously with the movement of the cover glass 22 in a direction of the X axis in a state that external light is shut off and a light emitting section 28 is lighted, calculates each of light transmittances by dividing pixel values considerably smaller than the other pixel values among pixel values obtained at each time as to each pixel by the other pixel values and detects an image of the dust projected on the imaging element 20 by an light transmittance distribution obtained by the light transmittance of each pixel. Then the imaging apparatus works out the dust image (unmagnification image) obtained from the imaging element 20 in the case of assuming that a light receiving face of the imaging element 20 is located at a position on the surface of the cover glass 22 through the use of an interpolation processing method such as a bilinear method by using the dust image and distances Lg, Ls from the light emitting section 58 up to the cover glass 22 and the light receiving face of the imaging element 20. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention belongs to the technical field of image pickup apparatuses, and in particular, if dust such as a filter or glass disposed on an optical path between an image pickup element and a shooting optical system adheres, the image quality of a shot image may be affected. The present invention relates to a countermeasure technique when dust adheres to a dust adhesion target object.

  Conventionally, for example, in a single-lens reflex type camera, various techniques have been proposed for suppressing deterioration in image quality of captured images caused by the presence of dust attached to a filter such as a low-pass filter when an interchangeable lens is attached or detached. (For example, refer to Patent Documents 1 and 2 below).

  In Patent Document 1, for the purpose of suppressing deterioration in image quality of an image obtained from an imaging device due to the presence of dust attached to a filter that guides subject light to the imaging device, during the exposure of the imaging device, The filter is moved in parallel with the light receiving unit of the imaging device, the time for which the subject light guided to the light receiving unit by the dust is blocked is shortened, and the amount of shadow per unit time in the light receiving unit is compared with the case where the filter is not moved. Thus, a technique for reducing the number is disclosed.

  In Patent Document 2, the CCD performs an imaging operation in a state where light other than the backlight does not enter, the pixel data obtained from each pixel by this imaging operation is compared with a threshold value, and the pixel value is determined from the threshold value. A pixel that outputs low pixel data is detected as a pixel to which dust (dust) is attached, and the pixel data of this pixel is not surrounded by the pixel data obtained from the pixel. A technique for interpolating with pixel data of a pixel located is described.

In the field of ships and trains, a technique is known in which a circular glass window is swirled and rainwater and wave droplets are blown away by centrifugal force for the purpose of ensuring visibility.
JP 2002-10137 A JP 2000-31314 A

  However, in Patent Document 1, since the movement locus of dust is linear or circular, a thin linear or circular shadow remains in the captured image. Such shadows are visually noticeable.

  In Japanese Patent Laid-Open No. 2004-260688, since pixels detected as dust (dust) are detected and interpolated by pixel data of pixels located around the pixels are used as pixel data of the pixels. When the image quality is large or the amount of dust is relatively large, it is difficult to restore an image that is faithful to the subject image, and it is inevitable that the image quality of the captured image is deteriorated.

  Also, in the field of ships and trains, the technology of turning round glass windows to blow rainwater and splashes is enough to ensure visibility during operation of ships, etc. When considering application to removal, it does not have the ability to remove even such minute dust, and it is difficult to obtain a sufficient image quality of a captured image.

  The present invention has been made in view of the above circumstances, and even when dust is present on a cover glass or the like disposed on an optical path between an imaging element and a photographing optical system, the influence of the dust is small. An object of the present invention is to provide a dust detection device, an imaging device, a dust detection method, and a program capable of obtaining a beautiful image.

  The invention according to claim 1 is disposed on an optical path between a photographing optical system that forms an optical image of a subject and an image pickup device in which an image pickup surface is arranged on an image forming surface of the photographing optical system. A dust detection device for detecting dust adhering to a dust adhering target object, the light irradiation means for irradiating the dust adhering target object and the image sensor, and the dust adhering object relative to the image sensor Driving means for moving in a predetermined direction, and blocking the outside light and irradiating light substantially uniformly by the light irradiating means, while causing the driving means to move the dust adhesion target object, A control unit that causes the imaging device to perform an imaging operation a plurality of times and a detection unit that compares a plurality of captured images obtained by the imaging operation and detects a dust image included in the captured image, To do.

  The invention according to claim 7 is disposed on an optical path between an imaging optical system that forms an optical image of a subject and an imaging device in which an imaging surface is disposed on an imaging surface of the imaging optical system. A dust detection method for detecting dust adhering to a dust adhesion target object, wherein the control means blocks external light and causes the light irradiation means to irradiate the dust adhesion target object and the image sensor substantially uniformly. In this state, the driving unit causes the imaging device to perform an imaging operation a plurality of times while causing the driving unit to perform a relative movement of the dust adhesion target object with respect to the imaging device in a predetermined direction. A step of comparing a plurality of captured images obtained by the operation and detecting an image of dust contained in the captured image.

  The invention according to claim 9 is disposed on an optical path between an imaging optical system that forms an optical image of a subject and an imaging device in which an imaging surface is disposed on an imaging surface of the imaging optical system. A program for causing a dust detection apparatus to realize a function of detecting dust attached to a dust adhesion target object, wherein the dust detection apparatus blocks external light and the light irradiation means includes the dust adhesion target object and the In a state where the image sensor is irradiated with light substantially uniformly, the image pickup device performs an image pickup operation a plurality of times while causing the drive unit to move the dust adhesion target body relative to the image sensor in a predetermined direction. And a control means for comparing a plurality of captured images obtained by the imaging operation to function as detection means for detecting an image of dust contained in the captured image.

  According to the first, seventh, and ninth aspects of the present invention, the dust adhesion target object with respect to the image sensor is obtained in a state where the external light is blocked and the light irradiation means substantially uniformly irradiates the dust adhesion target object and the image sensor with light. The image sensor is caused to perform an imaging operation a plurality of times while performing relative movement in a predetermined direction, and a plurality of captured images obtained by the imaging operation are compared to detect a dust image included in the captured image. Since it did in this way, the dust adhering to a dust adhesion target object is detectable.

  Further, as in the inventions described in claims 4 and 5 below, it is possible to accurately perform the restoration process with almost no influence of temporal changes in characteristics of the light irradiation means and the imaging device. It becomes.

  According to a second aspect of the present invention, in the dust detection device according to the first aspect, an image of the dust detected by the detection unit, and an optical axis direction from the light irradiation unit to the dust adhesion target object and the image sensor And a derivation means for deriving an equal-magnification image of the dust adhering to the dust adhering target object using the distance in (3).

  According to an eighth aspect of the present invention, in the dust detection method according to the seventh aspect, the derivation means includes an image of the dust detected by the detection means, and from the light irradiation means to the dust adhesion target object and the image sensor. And a step of deriving an equal-magnification image of the dust adhering to the dust adhesion object using the distance in the optical axis direction.

  According to a tenth aspect of the present invention, in the program according to the ninth aspect, the dust detection device further includes an image of the dust detected by the detection means, and the dust adhering object and the imaging from the light irradiation means. This is a program for functioning as a derivation means for deriving the same size image of the dust adhering to the dust adhering target object using the distance in the optical axis direction to the element.

  According to the second, eighth, and tenth aspects of the present invention, the detected dust image and the distance in the optical axis direction from the light irradiation means to the dust-adhering target object and the image sensor are used. Since the same-size image of the dust adhering to the camera is derived, even if dust is present on the object to which the dust is attached, the influence of the dust is removed or suppressed from the photographed image using the same-size image. When the restoration process is performed, it is possible to perform an accurate restoration process.

  Note that the equal-magnification image means that when the light receiving surface of the image sensor is located at substantially the same position in the optical axis direction as the dust adhering surface of the dust adhering target, An image.

  According to a third aspect of the present invention, in the dust detection apparatus according to the first or second aspect, the detection unit projects a dust image from the plurality of photographed images at the position of each pixel of the image sensor. And a first pixel value when the dust image is not projected and a second pixel value when the dust image is not projected, and using the first and second pixel values, The transmittance of irradiation light is calculated, and the dust image is detected using a transmittance distribution obtained from the transmittance calculated for the position of each pixel.

  According to the present invention, the first pixel value when the dust image is projected from the plurality of captured images and the second pixel value when the dust image is not projected from the plurality of captured images for each pixel position. And calculating the transmittance of the irradiation light at the position of the pixel using the first and second pixel values, and using the transmittance distribution obtained from the transmittance calculated for the position of each pixel. Since the dust image is detected, the image restoration process can be performed for each pixel when the restoration process is performed.

  According to a fourth aspect of the present invention, the optical system is disposed on an optical path between an imaging optical system that forms an optical image of a subject and an imaging device in which an imaging surface is disposed on an imaging surface of the imaging optical system. A dust detection device for detecting dust adhering to a dust adhering object, wherein the dust adhering object and the image sensor are irradiated with light, and external light is blocked, and light is emitted by the light irradiation means. The control unit that causes the imaging device to perform an imaging operation in a state where the imaging element is irradiated, the storage unit that stores a predetermined image in advance, the captured image obtained by the imaging operation and the predetermined image are compared, and And a detecting means for detecting an image of dust contained in the photographed image.

  According to the present invention, a captured image obtained by an imaging operation in a state where external light is blocked and light is irradiated by a light irradiation unit is compared with a predetermined image, and an image of dust included in the captured image is compared. Therefore, it is possible to easily detect the dust adhering to the dust adhering target.

  According to a fifth aspect of the present invention, in the dust detection device according to the fourth aspect, an image of the dust detected by the detection unit, and an optical axis direction from the light irradiation unit to the dust adhesion target object and the image sensor And a derivation means for deriving an equal-magnification image of the dust adhering to the dust adhering target object using the distance in (3).

  According to the present invention, the same-size image of the dust attached to the dust adhesion target object is derived using the dust image and the distance in the optical axis direction from the light irradiation means to the dust adhesion target object and the image sensor. Therefore, as the predetermined image, for example, when it is considered that almost no dust is attached to the target object (for example, immediately after the manufacture of the device), the external light is blocked and the light irradiation means is used. The image of dust included in the photographed image can be easily detected by using an image obtained by performing an imaging operation in a state where light is applied to the target object and the image sensor. Compared with the present invention, the process of deriving the same size image of the dust is simplified.

  According to a sixth aspect of the present invention, there is provided an apparatus main body including a lens unit including a photographing optical system that forms an optical image of a subject, and an imaging element having an imaging surface disposed on an imaging surface of the photographing optical system. An imaging apparatus in which the lens unit is configured to be detachable from the apparatus main body, and includes the dust detection apparatus according to any one of claims 1 to 5. is there.

  According to this invention, in the image pickup apparatus in which the lens unit is configured to be detachable from the apparatus main body, the dust unit easily attaches to the object to which the dust is attached, and the action of the invention according to any one of claims 1 to 5 is achieved. can get.

  According to the first, seventh, and ninth aspects of the invention, it is possible to detect the dust adhering to the dust adhering target and to be almost affected by the temporal change in the characteristics of the light irradiation means and the image sensor. Therefore, the restoration process can be performed accurately.

  According to the second, eighth, and tenth aspects of the invention, since an accurate restoration process can be performed, an image that is as faithful as possible to the subject image can be obtained when the restoration process is performed.

  According to the third aspect of the present invention, the image restoration process can be performed for each pixel. Therefore, when the restoration process is performed, an image as faithful as possible to the subject image can be obtained.

  According to invention of Claim 4, the dust adhering to a dust adhesion target object can be detected easily.

  According to the invention described in claim 5, since the process of deriving the same size image of the dust is simplified as compared with the invention described in claim 3, the time required for deriving the same size image of the dust is claimed. The invention can be shortened compared to the invention described in Item 3, and when this processing is realized by a program, the program can be designed more easily than the invention described in Item 3. it can.

  According to a sixth aspect of the present invention, in the imaging apparatus in which the lens unit is configured to be detachable from the apparatus main body so that dust is likely to adhere to the target object to which dust is attached. The effect of the invention can be obtained.

  Hereinafter, a first embodiment of an imaging apparatus according to the present invention will be described. FIG. 1 is a front view showing the configuration of a digital camera according to the first embodiment of the imaging apparatus, FIG. 2 is a rear view showing the configuration of the digital camera, and FIG. 3 is a diagram showing the internal configuration of the digital camera. . 1 to 3, the same members and the like are denoted by the same reference numerals.

  As shown in FIGS. 1 and 2, the digital camera 1 according to the present embodiment is a single-lens reflex type camera in which an interchangeable lens (lens unit) 2 is detachably attached to a box-shaped camera body 1A. It is.

  The digital camera 1 includes an interchangeable lens 2 attached to the front center of the camera body 1A, a first mode setting dial 3 disposed at an appropriate position on the upper surface, a shutter button 4 disposed at an upper corner, and a rear left side. An LCD (Liquid Crystal Display) 5 disposed on the LCD 5, a setting button group 6 disposed below the LCD 5, a direction key 7 disposed on the side of the LCD 5, and an inner side of the direction key 7. Push button 8, optical viewfinder 9 disposed above LCD 5, main switch 10 disposed on the side of optical viewfinder 9, and second mode setting disposed in the vicinity of main switch 10 A dial 11 and a connection terminal portion 12 disposed above the optical viewfinder 9 are provided.

  The interchangeable lens 2 is configured by arranging a plurality of lenses as optical elements in a direction perpendicular to the paper surface of FIG. As an optical element built in the interchangeable lens 2, a zoom lens 13 (see FIG. 6) for performing zooming and a focus lens 14 (see FIG. 6) for adjusting the focus are provided, each of which has an optical axis. By being driven in the direction, zooming and focus adjustment are performed.

  The interchangeable lens 2 is provided with a not-shown operation ring that can rotate along the outer peripheral surface of the lens barrel at a suitable position on the outer periphery of the lens barrel. The zoom lens 13 rotates and rotates the operation ring. This is a manual zoom lens that moves in the direction of the optical axis in accordance with and is set to a zoom magnification (imaging magnification) according to the position of the movement destination. The interchangeable lens 2 can be removed from the camera body 1A by pressing a not-shown removal button.

  The first mode setting dial 3 is a substantially disk-shaped member that can be rotated on a surface that is substantially parallel to the top surface of the digital camera 1, and a shooting mode for taking a still image or a moving image or a reproduction for playing a recorded image. This is for selectively selecting a mode and a function mounted on the digital camera 1 such as a mode. Although not shown, on the upper surface of the first mode setting dial 3, characters indicating the respective functions are written at predetermined intervals along the outer peripheral edge thereof, and an index provided at an appropriate position on the camera body 1A side. The function corresponding to the character set at the opposite position is executed.

  The shutter button 4 is a button that is pressed in two stages, that is, a half-pressing operation in which it is pressed halfway and a full-pressing operation in which it is fully pressed. This is for indicating the timing. When the shutter button 4 is half-pressed, an imaging standby state in which exposure control values (shutter speed and aperture value) are set is set, and when the shutter button 4 is fully pressed, the storage unit 54 described later is set. An exposure operation by the imaging unit 19 for generating an image of a subject to be recorded in (see FIG. 6) is started.

  The half-pressing operation of the shutter button 4 is detected when a switch S1 (not shown) is turned on, and the full pressing operation of the shutter button 4 is detected when a switch S2 (not shown) is turned on.

  The LCD 5 includes a color liquid crystal panel, displays an image captured by the imaging unit 19, reproduces and displays a recorded image, and displays a setting screen for functions and modes installed in the digital camera 1. Is. Instead of the LCD 5, an organic EL or plasma display device may be used.

  The setting button group 6 is a button for performing operations for various functions mounted on the digital camera 1. In the present embodiment, the setting button group 6 includes a dust removal button 6a for inputting an instruction to start execution of a dust removal operation described later.

  The direction key 7 has an annular member provided with a plurality of pressing portions (portions indicated by triangles in the drawing) arranged at regular intervals in the circumferential direction. The pressing operation of the pressing portion is detected by the contact (switch). The push button 8 is arranged at the center of the direction key 7.

  The direction key 7 and the push button 8 are used to change the shooting magnification (movement of the zoom lens in the wide direction or the tele direction), frame advance of the recorded image to be reproduced on the LCD 5, and shooting conditions (aperture value, shutter speed, flash emission). This is for inputting an instruction such as setting of presence / absence).

  The optical viewfinder 9 optically displays a range where a subject is photographed. The main switch 10 is a two-contact slide switch that slides to the left and right. When set to the left, the main power supply of the digital camera 1 is turned on, and when set to the right, the main power supply is turned off.

  The second mode setting dial 11 has a mechanical configuration similar to that of the first mode setting dial 3 and performs operations for various functions mounted on the digital camera 1. The connection terminal unit 12 is a terminal for connecting an external device such as a flash (not shown) to the digital camera 1.

  As shown in FIG. 3, an optical viewfinder 9, an AF drive unit 15, an imaging unit 19, a shutter unit 27, a mirror box 28, a phase difference AF module 33, and overall control are provided inside the camera body 1A. Part 37 is provided.

  The AF drive unit 15 includes an AF actuator 16, an encoder 17, and an output shaft 18. The AF actuator 16 includes a motor such as a DC motor, a stepping motor, and an ultrasonic motor that generate a driving source, and a speed reduction system (not shown) for reducing the rotational speed of the motor.

  Although not described in detail, the encoder 17 detects a rotation amount transmitted from the AF actuator 16 to the output shaft 18, and the detected rotation amount is used to calculate the position of the photographing optical system 38 in the interchangeable lens 2. Used. The output shaft 18 transmits the driving force output from the AF actuator 16 to a lens driving mechanism 40 described later in the interchangeable lens 2.

  FIG. 4 is an exploded perspective view showing the structure of the imaging unit 19. The imaging unit 19 is disposed substantially in parallel with the rear surface of the camera body 1A. As shown in FIG. 4, the imaging device 20, a package 21, a cover glass 22, and an excitation mechanism are provided. 23, a pressure contact member 24, and a capturing member 26.

  The imaging element 20 has a plurality of photoelectric conversion elements, such as photodiodes, which are two-dimensionally arranged in a matrix, and each light receiving surface of each photoelectric conversion element has different spectral characteristics, for example, R (red) and G (green). ), B (blue) color filter with a Bayer array CMOS (Complementary Metal-Oxide Semiconductor) color area sensor in which the color filters are arranged in a ratio of 1: 2: 1. The image sensor 20 is disposed in the package 21 so that the light receiving surface thereof is substantially parallel to a plane orthogonal to the optical axis of the imaging optical system 38, and an object imaged by the imaging optical system 38 (see FIG. 6). The optical image is converted into analog electrical signals (image signals) of R (red), G (green), and B (blue) color components, and output as image signals of R, G, and B colors.

  The package 21 is made of a material such as ceramic or plastic, and is, for example, a rectangular member that houses the image pickup device 20. The package 21 includes a plurality of electrodes 21a. In FIG. 3, the direction perpendicular to the paper surface is the X axis, the vertical direction in FIG. 3 is the Y axis, and the direction perpendicular to the X axis and the Y axis (shooting optical system). Assuming a three-dimensional coordinate system with the Z axis as the optical axis L direction of 38), the electrode 21a is installed on the substrate 25 via a connection between the terminals on the substrate 25 arranged on the XY plane. Has been.

  When the package 21 is viewed from the Z-axis direction, a rectangular first hollow portion 21b and a rectangular-shaped second hollow portion 21c smaller than the first hollow portion 21 are continuous in the X-axis direction. A hollow portion 21d having a convex shape in the axial direction is formed. In the hollow portion 21d, the image sensor 20 is accommodated, and a cover glass 22, a vibration mechanism 23, and a pressure contact member 24, which will be described later, are disposed.

  A cover glass 22 (an example of an object to which dust is attached in the claims) is disposed in the package 21 on the front side of the imaging element 20 (on the imaging optical system 38 side), and the light from the imaging optical system 38 is captured by the imaging element. This is to protect the image pickup device 20 from dust entering the package 21 while being guided to 20.

  In the digital camera 1 of the present embodiment, since the interchangeable lens 2 can be interchanged with the camera body 1A, dust may enter the camera body 1A when the interchangeable lens 2 is attached or detached. Examples of the dust include soil dust from the ground, combustion ash from combustion of combustion objects in the factory, combustion ash contained in exhaust gas from automobiles, and fibrous cotton dust generated from clothes. .

  As described above, the cover glass 22 is provided to protect the image sensor 20 from the various kinds of dust, but is disposed on the optical path between the imaging optical system 38 and the image sensor 20. If dust that has entered the camera body 1A when the interchangeable lens 2 is attached or detached adheres to the surface of the cover glass 22, a shadow of the dust is projected on the photographed image, resulting in a deterioration in the quality of the photographed image. It becomes.

  Therefore, in the present embodiment, in order to suppress or prevent dust from adhering to the surface of the cover glass 22, a coating layer for preventing dust adhesion is formed on the surface of the cover glass 22 by covering it with a fluororesin or silicon resin. The adhesion of dust to the surface of the cover glass 22 is made small.

  The vibration mechanism 23 is a laminated piezoelectric element formed by laminating piezoelectric elements made of ceramics made of a material such as barium titanate or lead zirconate titanate, and one end portion in the laminating direction is covered. The glass 22 is disposed in the second hollow portion 21c of the package 21 in a state where the glass 22 is in contact with an appropriate position.

  An unillustrated electrode portion of the vibration mechanism 23 is connected to a later-described overall control portion (see FIG. 6) disposed on the substrate 25 by a signal line 23a, and the overall control portion 37 is connected via the signal line 23a. When a pulsed driving signal (driving voltage) is given from the piezoelectric element, each piezoelectric element is deformed (stretched) in the stacking direction. Even if the dust-preventing coating layer is formed on the cover glass 22 by applying a rapid displacement (impact) to the cover glass 22 using the characteristics of the piezoelectric element, the vibration mechanism 23 still has the cover glass 22. The dust adhering to the surface of the cover glass 22 is dropped from the surface of the cover glass 22.

  That is, it is generally said that adhesion of powder particles (small size dust) is caused by electrostatic force, intermolecular force, liquid cross-linking force, etc. When the size of the particles is reduced, the surface area relative to the mass of the particles is reduced. The ratio increases, and the electrostatic force and the like described above are proportional to the surface area. Therefore, dust having a small size tends to adhere to the cover glass 22.

  When a rapid displacement (impact) is applied to the cover glass 22, an inertial force that tries to stay at the current position acts on the dust attached to the cover glass 22. Since the magnitude of the inertial force is proportional to the mass and acceleration of the particles, the displacement (vibration) of acceleration is applied to the cover glass 22 so that the inertial force acting on the dust is larger than the adhesion force. Can be dropped.

  The acceleration of the displacement varies depending on the waveform of the drive signal applied to the vibration mechanism 23. FIG. 5A is a graph showing a waveform of a sine wave drive signal applied to the vibration mechanism 23 and a change in acceleration when the sine wave drive signal is applied, and FIG. 5 is a graph showing the waveform of a pulse wave drive signal applied to the vibration mechanism 23 and the change in acceleration when the pulse wave drive signal is applied. 5A and 5B, the horizontal axis of the graph showing the drive signal is time, the vertical axis is voltage, the horizontal axis of the graph showing the change in acceleration is time, and the vertical axis is acceleration. Further, the amplitude of the waveform of the drive signal (maximum value of the drive voltage) is the same (voltage V1) for both drive signals.

  As shown in FIG. 5A, when the drive signal applied to the vibration mechanism 23 is a sine wave, the acceleration of the displacement of the cover glass 22 has a maximum value (amplitude) A1 of the drive signal. It changes in a sine wave shape corresponding to the period. On the other hand, as shown in FIG. 5B, when the drive signal applied to the vibration mechanism 23 is a pulse wave, each piezoelectric device is compared with the case where the drive signal shown in FIG. Since the element rapidly expands and contracts in a short time, the maximum acceleration value A2 becomes larger than that in the case of the sine wave drive signal (FIG. 5A) (A2> A1). In the present embodiment, in order to remove dust adhering to the cover glass 22 as much as possible, a pulsed drive signal as shown in FIG. The acceleration to be done is increased.

  Returning to FIG. 4, the pressure contact member 24 is formed of a V-shaped member that can be elastically deformed so that the crossing angle changes, and biasing means that biases the cover glass 22 toward one end portion of the vibration mechanism 23. It has a function as a (spring). The pressure contact member 24 has a vibrating mechanism with respect to the cover glass 22 in the X-axis direction in a state where the intersecting portion 24a is in contact with the end surface of the cover glass 22 and the end portions 24b and 24c are in contact with appropriate positions on the inner wall surface of the package 21, respectively. 23 is disposed at a position opposite to 23. The pressure contact member 24 is not limited to the above-described member, and any member that urges the cover glass to the vibration mechanism 23 such as a winding spring or a leaf spring may be used.

  In the vicinity of the lower end surface of the cover glass 22, a capturing member 26 for capturing dust that has fallen due to the operation of the vibration exciting mechanism 23 is disposed. The capturing member 26 is made of, for example, a porous member such as a sponge, and captures dust that has fallen from the surface of the cover glass 22 by the operation of the vibration excitation mechanism 23, so that the dust once scattered from the surface of the cover glass 22 is captured by the camera. The inside of the main body 1A is scattered or prevented from adhering to the cover glass 22 or the surface of the lens again. The opening 21d of the package 19 is closed together with the cover glass 22 by a sealing member made of an elastic body so as to prevent dust from adhering to the image sensor 20.

  Returning to FIG. 3, the shutter unit 27 includes a focal plane shutter (hereinafter simply referred to as a shutter), and is disposed between the back surface of the mirror box 28 and the imaging unit 19.

  The optical viewfinder 9 is disposed on an upper portion of a mirror box 28 disposed substantially at the center of the camera body 1A, and includes a focusing screen 29, a prism 30, an eyepiece lens 31, and a viewfinder display element 32. It is configured. The prism 30 inverts the left and right of the image on the focusing screen 29 and guides it to the photographer's eye through the eyepiece lens 31 so that the subject image can be visually recognized. The finder display element 32 displays a shutter speed, an aperture value, an exposure correction value, and the like at the bottom of the display screen formed in the finder field frame 9a (see FIG. 2).

  The phase difference AF module 33 is disposed at the bottom of the mirror box 28 and detects the in-focus position by a phase difference detection method that is a well-known technique. The phase difference AF module 33 has a configuration disclosed in, for example, Japanese Patent Application Laid-Open No. 11-84226 proposed by the present applicant, and a detailed description of the configuration is omitted.

  The mirror box 28 includes a quick return mirror 34 and a sub mirror 35. As shown by the solid line in FIG. 3, the quick return mirror 34 is centered on the rotation fulcrum 36 and is tilted approximately 45 degrees with respect to the optical axis L of the photographing optical system 38 (hereinafter referred to as tilted posture). As shown by the phantom line 3, it is configured to be rotatable between a posture (hereinafter referred to as a horizontal posture) substantially parallel to the bottom surface of the camera body 1A.

  The sub mirror 35 is disposed on the back side (the imaging unit 19 side) of the quick return mirror 34, and as shown by a solid line in FIG. 3, the sub mirror 35 is inclined by approximately 90 degrees with respect to the quick return mirror 34 in the inclined attitude. (Hereinafter referred to as the tilted posture) and the quick return mirror 34 between the horizontal posture and the substantially parallel posture (hereinafter referred to as the horizontal posture) as shown by the phantom line in FIG. Thus, it can be displaced. The quick return mirror 34 and the sub mirror 35 are driven by a mirror drive mechanism 44 (see FIG. 6) described later.

  The quick return mirror 34 and the sub mirror 35 are inclined until the shutter button 4 is fully pressed, and the quick return mirror 34 reflects most of the light flux by the photographing optical system 38 in the direction of the focusing screen 29. The remaining light flux is transmitted, and the sub mirror 35 guides the light flux transmitted through the quick return mirror 34 to the phase difference AF module 33. At this time, the display of the subject image by the optical viewfinder 9 and the focus adjustment operation of the phase difference detection method by the phase difference AF module 33 are performed. On the other hand, since the light beam is not guided to the imaging unit 19, the image of the subject by the LCD 5 is displayed. No display is done.

  On the other hand, when the shutter button 4 is fully pressed (while the recording image is being captured), the quick return mirror 34 and the sub mirror 35 are in a horizontal posture, and the quick return mirror 34 and the sub mirror 35 are retracted from the optical axis L. Nearly all the light beam that has passed through the photographing optical system 38 is guided to the image pickup unit 19. At this time, the subject image is displayed on the LCD 5, while the subject image is not displayed on the optical viewfinder 9 and the phase difference detection type focus adjustment operation by the phase difference AF module 33 is not performed.

  The overall control unit 37 is composed of a microcomputer having a built-in storage unit 65 (see FIG. 6) to be described later such as a ROM for storing a control program and a flash memory for temporarily storing data. Will be described later.

  Next, the interchangeable lens 2 attached to the camera body 1A will be described. As shown in FIG. 3, the interchangeable lens 2 includes a photographing optical system 38, a lens barrel 39, a lens driving mechanism 40, a lens encoder 41, and a storage unit 42.

  The photographing optical system 38 is provided in the zoom lens 13 (see FIG. 6) for changing the photographing magnification (focal length), the focus lens 14 (see FIG. 6) for adjusting the focal position, and the camera body 1A. A diaphragm 43 for adjusting the amount of light incident on the imaging unit 19 and the like, which will be described later, is held in the direction of the optical axis L in the lens barrel 39, and captures the optical image of the subject and captures the optical image. And so on. The focus adjustment operation is performed by driving the photographing optical system 38 in the direction of the optical axis L by the AF actuator 16 in the camera body 1A. Note that the change of the photographing magnification (focal length) (zoom operation) is manually performed by a zoom ring (not shown) as described above.

  The lens driving mechanism 40 includes, for example, a helicoid and a gear (not shown) that rotates the helicoid. The lens driving mechanism 40 receives a driving force from the AF actuator 16 via the coupler C, and the photographing optical system 38 is integrated with the optical axis L. It is moved in the direction of the parallel arrow A. The moving direction and moving amount of the photographic optical system 38 depend on the rotating direction and the rotating speed of the AF actuator 16, respectively.

  The lens encoder 41 moves integrally with the lens barrel 39 while being in sliding contact with the encode plate in which a plurality of code patterns are formed at a predetermined pitch in the optical axis L direction within the moving range of the photographing optical system 38. And an encoder brush (not shown) for detecting the amount of movement of the photographing optical system 38 during focus adjustment.

  When the interchangeable lens 2 is mounted on the camera body 1A and a data request is received from the overall control section 37 in the camera body 1A, the storage section 42 stores the stored contents in the overall control section 37 in the camera body 1A. It is to provide. The storage unit 42 stores information on the amount of movement of the photographing optical system 38 output from the lens encoder 41, the current aperture diameter of the diaphragm 43, and the like.

  Next, an electrical configuration of the digital camera 1 according to the present embodiment will be described. FIG. 6 is a block diagram showing an electrical configuration of the entire digital camera 1 with the interchangeable lens 2 attached to the camera body 1A. Moreover, the same code | symbol is attached | subjected about the member etc. which are the same as FIGS. In addition, a dotted line in FIG. 6 indicates a member or the like mounted in the interchangeable lens 2.

  As shown in FIG. 6, the photographing optical system 38 corresponds to the photographing optical system 38 shown in FIG. 3, and is for adjusting the focal point and the zoom lens 13 for changing the photographing magnification (focal length). The focusing lens 14 is provided in the lens barrel 39. The AF actuator 16, encoder 17, output shaft 18, lens drive mechanism 40, and lens encoder 41 correspond to the AF actuator 16, encoder 17, output shaft 18, lens drive mechanism 40, and lens encoder 41 shown in FIG. 3, respectively. is there. The storage unit 42 corresponds to the storage unit 42 shown in FIG. The mirror box 28 includes a quick return mirror 34 and a sub mirror 35, and the phase difference AF module 33 corresponds to the phase difference AF module 33 shown in FIG.

  The image sensor 20 corresponds to the image sensor 20 shown in FIG. 4, and the timing control circuit 47 described later starts and ends the exposure operation of the image sensor 20 and reads out the output signal of each pixel in the image sensor 20. An imaging operation such as (horizontal synchronization, vertical synchronization, transfer) is controlled.

  The mirror unit 44 includes a quick return mirror 34 and a sub mirror 35. The mirror drive mechanism 44 drives the quick return mirror 34 and the sub mirror 35 between the tilted posture and the horizontal posture, and the operation is controlled by the overall control unit 37.

  The signal processing unit 45 performs predetermined analog signal processing on the analog image signal output from the image sensor 20. The signal processing unit 45 includes a CDS (correlated double sampling) circuit and an AGC (auto gain control) circuit, reduces noise of the image signal by the CDS circuit, and adjusts the level of the image signal by the AGC circuit.

  The A / D conversion unit 46 converts the analog R, G, B pixel signals output from the signal processing unit 45 into digital pixel signals composed of a plurality of bits (for example, 10 bits). Hereinafter, the pixel signal after the A / D conversion processing by the A / D conversion unit 46 is referred to as pixel data in order to distinguish it from an analog pixel signal.

  The timing control circuit 47 generates clocks CLK1 and CLK2 based on the reference clock CLK0 output from the overall control unit 37, and outputs the clock CLK1 to the imaging unit 19 and the clock CLK2 to the A / D conversion unit 46. Thus, the operations of the imaging unit 19 and the A / D converter 46 are controlled.

  The image processing unit 48 is based on the black level correction circuit 49 that corrects the black level to the reference black level for the pixel data after the A / D conversion processing by the A / D conversion unit 46, and the white reference according to the light source. White balance circuit (indicated as WB circuit in FIG. 6) 50, R (red), G (green) for converting the level of the pixel data of each color component of R (red), G (green), and B (blue) , B (blue) is provided with a γ correction circuit 51 for correcting the γ characteristic of the pixel data of each color.

  The image memory 52 temporarily stores the image data output from the image processing unit 48 in the shooting mode, and is used as a work area for performing processing described later by the overall control unit 37 on the image data. In the reproduction mode, this is a memory in which image data read out from the storage unit 54 described later by the overall control unit 37 is temporarily stored.

  The VRAM 53 has a recording capacity for image signals corresponding to the number of pixels of the LCD 5, and is a pixel signal buffer memory constituting an image reproduced and displayed on the LCD 5. The LCD 5 corresponds to the LCD 5 shown in FIG.

  The storage unit 54 includes a memory card or a hard disk made up of semiconductor storage elements, and stores images generated by the overall control unit 37.

  The input operation unit 55 includes the first mode setting dial 3, the shutter button 4, the setting button group 6, the direction key 7, the push button 8, the main switch 10, the second mode setting dial 11, etc. This is for input to the control unit 37.

  The dust removing unit 56 includes a vibration mechanism 23 that vibrates the cover glass 22 in the imaging unit 19, a pressure contact member 24 that biases the cover glass 22 toward the vibration mechanism 23, and a portion near the lower end surface of the cover glass 22. It includes a capture member 24 disposed (see FIG. 4).

  As described above, the digital camera 1 according to the present embodiment has a function of removing dust adhering to the cover glass 22, and the presence or absence of dust on the cover glass 22 and dust adhering to the cover glass 22 in the image. It has a function of detecting the included dust image (shadow due to dust), and an auxiliary light irradiation unit 57 described below is provided as a configuration for realizing the function. FIG. 7 is a perspective view illustrating a configuration of the auxiliary light irradiation unit 57.

  As shown in FIG. 7, the auxiliary light irradiation unit 57 includes a light emitting unit 58 made of, for example, an LED (Light Emitting Diode) disposed below the mirror box 28, and the light emitting unit 58 and the quick return mirror 34. And a lens 59 for diffusing light from the light emitting portion 58 and a small mirror 60 provided on the back surface of the quick return mirror 34 (the surface indicated by the arrow S in FIG. 3). ing. The light output from the light emitting unit 58 is diffused by the lens 59, the diffused light is reflected by the small mirror 60 toward the image sensor 20, and the reflected light is guided to the light receiving surface of the image sensor 20.

  The light emitting unit 58 is sufficiently small in size and can be regarded as a point light source, and when the quick return mirror 34 is in an inclined posture (in a period other than the period during which the recording imaging operation is performed), the light emitting unit 58 is. The arrangement positions of the light emitting unit 58, the lens, and the small mirror 60 are set so that the light from the light is irradiated onto the entire light receiving surface (imaging surface) of the image sensor 20. It should be noted that the amount of light output from the light emitting unit 58 is such that an image obtained by an imaging operation of the imaging device 20 performed at the time of dust detection, which will be described later, is not over-exposed (a phenomenon in which an image becomes white due to excessive luminance). The spectral distribution is set to be substantially white. The small mirror 60 transmits light guided from the photographing optical system 38 via the quick return mirror 34 toward the sub mirror 35.

  The overall control unit 37 controls the photographing operation and the reproduction operation in association with the driving of each member in the digital camera 1 shown in FIG. Further, in the present embodiment, the overall control unit 37 restores the degradation of the captured image due to the removal of dust attached to the cover glass 22 and the presence of dust still remaining on the cover glass 22 by the removal operation. In order to execute these processes, the apparatus is functionally provided with a light transmittance calculation unit 61, a dust size detection unit 62, a dust removal control unit 63, a restoration processing unit 64, and a storage unit 65. ing.

  In the following, a series of processes relating to dust attached to the cover glass 22 will be described. After the outline of this process is first described, detailed processes by the units 61 to 64 will be described. FIGS. 8 and 9 are flowcharts showing a series of processes relating to dust attached to the cover glass 22, which is performed by the overall control unit 30.

  As shown in FIG. 8, when an input for instructing the removal of dust is performed by the dust removal button 6a (YES in Step # 1), the overall control unit 37 determines whether dust is attached to the cover glass 22 or not. A process for detecting this is executed (step # 2), and if no dust is detected (NO in step # 3), the series of processes ends.

  On the other hand, when the dust is detected (YES in step # 3), overall control unit 37 executes a process of removing dust from cover glass 22 using dust removing unit 56 (step # 4). Then, overall control unit 37 executes again the process of detecting whether or not dust is attached to cover glass 22 (step # 5), and if no dust is detected (NO in step # 6). ) When the series of processing ends, but when dust is detected again (YES in step # 6), a dust image (described in a state where external light is shielded) obtained by the dust detection processing executed in step # 5. (Image obtained by the imaging operation performed in step 1) is stored (step # 7).

  Thereafter, as shown in FIG. 9, when the photographer gives an instruction to shoot, the overall control unit 37 determines whether or not a dust image is stored after completion of a series of shooting operations (YES in step # 11). Is confirmed (step # 12). If a dust image is stored (YES in step # 12), after performing a later-described restoration process (a process for removing or suppressing the influence of dust from the photographed image) (step # 13), the image data is stored. The data is converted into a predetermined format and stored in the storage unit 54 (step # 14).

  On the other hand, if the image of the dust is not stored (NO in step # 12), overall control unit 37 displays, for example, on LCD 5 to urge the user to instruct the start of the dust detection process (step 5). # 15) The process of step # 14 is executed without executing the restoration process.

  Next, detailed processing contents of each unit will be described. Depending on the type and amount of dust, the subject light guided from the photographing optical system 38 may be completely blocked (the light transmittance is 0%). Since some light passes through the dust, the dust image generated in the photographed image can be considered as an image in which the light guided from the photographing optical system 38 is attenuated by the presence of the dust. In the present embodiment, the description will be made on the assumption that the dust to be detected and removed does not completely block the light to the light receiving surface of the image sensor 20 but transmits part of the light. .

  In the state where the amount of incident light to the imaging unit 19 (cover glass 22) is made uniform with respect to the entire light receiving surface, the light transmittance calculating unit 61 affects the influence of dust on the actual incident light amount on each pixel. In other words, in the above state, the pixel value of each image captured by each pixel of the image sensor 20 is affected by dust. The ratio with respect to the pixel value when there is no pixel is calculated for each pixel position. Hereinafter, this ratio is referred to as light transmittance, and a light transmittance calculation method by the light transmittance calculator 61 will be described.

  First, when the dust removal button 6a is pressed, the light transmittance calculating unit 61 closes the diaphragm 43 and the shutter unit 27 to block outside light and then turns on the light emitting unit 58. Thereby, since the quick return mirror 34 is in an inclined posture, only the light from the light emitting unit 58 is uniformly guided to each part of the cover glass 22 after being diffused by the lens 59.

  In this state, the light transmittance calculation unit 61 causes the image sensor 20 to perform an imaging operation once, and then images the image sensor 20 in synchronization with the movement of the cover glass 22 in the X-axis direction (see FIG. 4). Make the action run multiple times. For the movement of the cover glass 22 performed at this time, the vibration mechanism 23 used in the dust removing operation described above is used. In general, the size of the dust adhering to the cover glass 22 is approximately several microns to several tens of microns, and even a large one is several hundred microns or less. Since it is considered that there is a low possibility that these dusts are clumped and adhered to the cover glass 22, the total movement amount of the cover glass 22 may be about 1 mm, for example.

  When dust adheres on the cover glass 22, when a plurality of captured images obtained by this series of imaging operations are compared, the image of the dust appears at different positions in the X-axis direction in each captured image.

  FIG. 10 shows pixel values of pixels belonging to a certain pixel column aligned in the X-axis direction in the image sensor 20 when the cover glass 22 is moved and the image sensor 20 is imaged at regular time intervals. 10 (a) is a graph, and FIG. 10 (b) to FIG. 10 (d) show pixel values when the imaging device 20 performs an imaging operation simultaneously with the start of movement of the cover glass 22 (time T = 0). Indicates a pixel value when the image pickup device 20 performs an image pickup operation at a time (time T = Δt, 2Δt, 3Δt) after a time Δt has elapsed from time T = 0. 10A to 10D, the X coordinate is set for the pixels belonging to the pixel column, and the position of each pixel is represented by the coordinates.

  FIG. 11 is a perspective view showing a projection state of the dust onto the image sensor 20 when dust is attached to the surface of the cover glass 22, and FIG. 12 is a side view showing the state. . As described above (as shown in FIG. 7), the actual arrangement position of the light emitting unit 58 and the lens 59 is arranged below the mirror box 28. In FIGS. 11 and 12, however, It is shown at a position facing the cover glass 22 that is considered to be optically equivalent to this actual arrangement position.

  As shown in FIGS. 11 and 12, when dust M adheres to the surface of the cover glass 22, pixels in a predetermined area located behind the dust M are irradiated with auxiliary light compared to other pixels. Since the light from the unit 57 is attenuated, the pixel value of the pixel signal output from this pixel is smaller than the pixel value of the pixel signal output from other pixels. The hatched portion on the cover glass 22 shown in FIGS. 11 and 12 indicates the dust M, and the hatched portion on the image sensor 20 indicates the shadow of the dust M.

  In the graph shown in FIG. 10A, a relatively large recessed portion is a pixel region onto which an image in which light is attenuated by dust M is projected, and as shown in FIGS. 10B to 10D, As the cover glass 22 is moved in the X-axis direction, the concave portion moves in the X-axis direction.

  10A to 10D, the directivity of the irradiation light of the light emitting unit 58, the distance from the light emitting unit 58 to the image sensor 20, or the lens 59 in the auxiliary light irradiation unit 57 is used. The pixel value gradually decreases as it goes to both sides in the X-axis direction due to a so-called peripheral light amount drop, but in the following, it is assumed that the pixel values are substantially the same except for the position where the dust M exists. Give an explanation.

Now, the pixel value of the pixel X at the position (X coordinate) x at time T is expressed as L (x, T), and the pixel X ₁ located at a certain position x ₁ in the X-axis direction (hereinafter referred to as this pixel) by paying attention to) that the pixel of interest X ₁ will be explained. The light transmittance calculator 61 calculates the pixel values L (x ₁ , 0), L (x ₁ , Δt), L (x ₁ , 2Δt) of the target pixel X ₁ at each time T = 0, Δt, 2Δt, 3Δt. , L (x ₁ , 3Δt) are compared with each other.

As a result, as shown in FIGS. 10A to 10D, the pixel value L (x ₁ , 0) at the time T = 0 of the pixel of interest X _{1 is} the current value at other times T = Δt, 2Δt, 3Δt. pixel value L of the pixel of interest _{X 1 (x 1, Δt)} , L (x 1, 2Δt), L (x 1, 3Δt) very than the (extremely) small, the target pixel X ₁ time T = Pixel values L (x ₁ , Δt), L (x ₁ , 2Δt), and L (x ₁ , 3Δt) at Δt, 2Δt, and 3Δt are L (x ₁ , Δt) ≈L (x ₁ , 2Δt) ≈L It can be seen that (x ₁ , 3Δt) and the maximum pixel value output by the pixel of interest X ₁ during the movement.

Therefore, the light transmittance calculating unit 61 uses the pixel value (x ₁ , 0) at time T = 0 as the pixel value when the shadow of dust is projected on the target pixel X ₁ (pixels affected by dust). and sets as the value), the time T = Delta] t, 2? t, a pixel value at _{3Δt L (x 1, Δt)} (≒ L (x 1, 2Δt) ≒ L (x 1, 3Δt) a), the target pixel X ₁ Is set as a pixel value (a pixel value not affected by dust) when no shadow of dust is projected on the screen.

Then, the light transmittance calculating unit 61 divides the pixel value L (x ₁ , 0) of the target pixel X ₁ at time T = 0 by the pixel value L (x ₁ , Δt). Thereby, the light transmittance at the position of the target pixel X ₁ can be calculated. The light transmittance is a value from 0 to 100 because it is converted to a percentage.

The same process is performed for the other pixels to derive the light transmittance distribution at the position of each pixel. FIG. 13 is a graph showing an example of the light transmittance distribution at the position of each pixel belonging to a certain pixel column aligned in the X-axis direction in the image sensor 20, and for example, in FIG. 13, the position x is x ₂ ≦ x ≦. it can be seen that dust image is projected to pixels located in a range of up to x _3.

  Thus, since it is thought that the dust image adhering to the cover glass 22 is projected on the pixel with the small calculated light transmittance, the area | region which consists of a pixel with a light transmittance smaller than a predetermined threshold value is shown. By detecting, the dust image projected on the image sensor 20 and its size can be detected.

  By the way, instead of such a light transmittance calculation method, the following calculation method may be employed.

  That is, at the time of shipment of the digital camera 1 (when it is considered that dust is hardly attached to the cover glass 22), the light emitting unit 58 is turned on with the outside light blocked, and the pixel value of each pixel (hereinafter referred to as a reference). (Referred to as pixel value). Thereafter, when the photographer gives a detection instruction using the dust removal button 6a, the light emitting unit 58 is turned on without moving the cover glass 22 as described above, and the image pickup device 20 performs an image pickup operation only once. Get the pixel value of the pixel. Then, the pixel value of each pixel is divided by the reference pixel value of the pixel, and the division value is converted into a percentage to calculate the light transmittance.

  According to such a calculation method, it is possible to easily detect the dust image included in the photographed image, so that the process of deriving the same-size image of dust is simpler than the calculation method described above. Become. Therefore, compared with the above-described calculation method that calculates the light transmittance using a plurality of captured images obtained by a plurality of imaging operations by the imaging element 20 in synchronization with the movement of the cover glass 22 in the X-axis direction. In addition, it is possible to shorten the time required for deriving the same-size image of dust, and to easily design a program that realizes this processing.

  However, in the above-described calculation method, there is a time difference between the shipment time and the detection instruction time, and the light amount of the light emitting unit 58, the light distribution, the sensitivity of the image sensor 20, and the like may change over time. For example, if the light intensity of the light emitting unit 58 changes between the shipment time of the digital camera 1 and the detection instruction time point, the reference pixel value obtained at the time of shipment and the detection instruction time point to be matched are not affected by dust. Since the pixel value in this case is different, accurate light transmittance cannot be obtained. In this way, if there is a time difference between the shipment time and the detection instruction time, an error occurs in the pixel value due to other factors such as changes over time of each member unrelated to the influence of dust, and the light transmittance calculation accuracy May decrease.

  In contrast, in the present embodiment, for the same pixel, the pixel value when the light is attenuated due to the presence of dust and the pixel value when the light is not attenuated by the dust are obtained at substantially the same time. By setting the light amount and light distribution of the light emitting unit 58 and the sensitivity of the image pickup device 20 to substantially the same conditions, the light transmittance is calculated under these conditions. This has the advantage that the light transmittance can be calculated with high accuracy.

  As described above, the image sensor 20 according to the present embodiment includes, for example, R (red), G (green), and B (blue) color filters having different spectral characteristics arranged in a ratio of 1: 2: 1. The light transmittance at the position of each pixel, which is an image sensor with a Bayer array and derived by the above processing, is the light transmittance of the color component corresponding to the color filter disposed in each pixel.

  For example, the light transmittance of red light for a pixel provided with an R (red) color filter, and the light transmittance of green light for a pixel provided with a G (green) color filter, The light transmittance of the blue light is derived for each of the pixels in which the B (blue) color filter is provided.

  Here, in FIG. 13, the light transmittance distribution for each pixel belonging to a certain pixel column aligned in the X-axis direction in the image sensor 20 is represented by a smooth curve. As shown in FIG. 14A, for example, in the horizontal pixel row W1 in which pixels of R (red) and G (green) are alternately arranged as shown in FIG. 14B, for example, G (green) and In the horizontal pixel row W2 in which B (blue) pixels are alternately arranged, as shown in FIG. 14C, a graph (distribution) affected by the light transmittance (transmission characteristics) of each color filter itself. It becomes.

  Thus, since the light transmittance of colors other than the color of the color filter disposed in the pixel is missing at the position of each pixel, in this embodiment, R (red), In order to obtain the light transmittance of G (green) and B (blue), the pixel value of the missing color component is calculated by interpolation processing using the pixel values of the pixels located around the pixel. I am doing so. FIG. 15 is a diagram for explaining this interpolation processing.

  As shown in FIG. 15A, for example, with respect to the position of a pixel provided with a G (green) color filter indicated by an arrow X, a pixel value of a G (green) component is obtained from the pixel. , R (red) component and B (blue) component pixel values are insufficient. Therefore, the pixel value of the insufficient R (red) component is calculated using the pixel value of the pixel in which the R (red) color filter is disposed among the pixels located around the pixel, Further, the missing B (blue) pixel value is calculated using the pixel values of the pixels provided with the B (blue) color filter among the pixels located around the pixel.

  That is, for the position of the pixel where the G (green) color filter indicated by the arrow X in FIG. 15A is disposed, the pixel value of the R (red) component is, for example, as shown in FIG. The average value of the R (red) pixel values obtained from the two pixels located on the left and right sides thereof, and the pixel value of the B (blue) component, for example, as shown in FIG. The average value of the B (blue) pixel values obtained from the two located pixels is used.

  For example, for the position of the pixel where the R (red) color filter indicated by the arrow Y is disposed, the pixel value of the insufficient G (green) component is, for example, as shown in FIG. The average value of the pixel values of two pixels having an intermediate pixel value among the four pixels in which the G (green) color filter adjacent to the pixel is arranged. Further, for example, as shown in FIG. 15 (e), the missing B (blue) pixel value is set to the pixel value of the four pixels in which the B (blue) color filter adjacent to the pixel is arranged. Average value.

  Similarly, with respect to the position of the pixel provided with the B (blue) color filter indicated by the arrow Z, for example, the pixel value of the insufficient G (green) component is shown in FIG. As shown, the average value of the pixel values of two pixels having an intermediate pixel value among the four pixels in which the G (green) color filter adjacent to the pixel is arranged is used. In addition, as shown in FIG. 15G, for example, the missing R (red) pixel value is calculated as the pixel value of four pixels provided with an R (red) color filter adjacent to the pixel. Average value. Note that the method of selecting a pixel to be subjected to such interpolation calculation is not limited to the above.

  As described above, at each time T = 0, Δt, 2Δt, and 3Δt, pixel values of missing color components are derived by interpolation processing using pixel values of surrounding pixels. Similarly to the light transmittance calculation method described above, for each color component, a pixel value when the shadow of the dust is not projected on the pixel X and a pixel value when the shadow of the dust is projected are derived. The light transmittance of each color component at the position of each pixel can be calculated from these pixel values.

  For example, as shown in FIG. 16, at each time T = 0, Δt, 2Δt, 3Δt, the pixel values of a certain G (green) pixel are “70”, “46.5”, “70.2”, If the pixel value is “69.9”, the pixel value when not affected by dust is set to “70”, and the pixel value when affected by dust is set to “46.5”. The light transmittance (46.5 / 70) × 100 of the G (green) component of the pixel is calculated.

  In the pixel, the pixel values of the R (red) component and the B (blue) component are derived from the surrounding pixels as described above. For example, as indicated by dotted lines in FIG. 16, pixel values “77”, “53.2”, “77.1”, “76.” of the R (red) component at each time T = 0, Δt, 2Δt, 3Δt. 9 ”is derived by interpolation, and the pixel values“ 89 ”,“ 65.3 ”,“ 89.1 ”,“ 88.8 ”of the B (blue) component at each time T = 0, Δt, 2Δt, 3Δt are obtained. It is assumed that it is derived by interpolation.

  At this time, in the R (red) component, the pixel value when not affected by dust is set to “77”, and the pixel value when affected by dust is set to “53.2”. G (green) light transmittance (53.2 / 77) × 100 is calculated. In the B (blue) component, the pixel value when not affected by dust is set to “89”, and the pixel value when affected by dust is set to “65.3”. The light transmittance of G (green) (65.3 / 89) × 100 is calculated.

  Through the above processing, as shown in FIG. 17, it is possible to derive the light transmittance distribution of each color component at the position of each pixel. In FIG. 16, when the time T = Δt, the pixel value in each color component is significantly different from the pixel values at the other times T = 0, 2Δt, 3Δt. It can be considered that the dust image is projected onto the pixel. In addition, as shown in FIG. 17, the light transmittance generally increases in the order of B (blue), R (red), and G (green). This is because the light transmittance ( This depends on the transmission characteristics) and the color of the dust.

  The movement pitch of the cover glass 22 may be set in consideration of the following. That is, when the amount of dust attached is small, the light transmittance can be calculated by moving the cover glass 22 only once at a relatively large movement pitch and performing an imaging operation before and after the movement. . This is because the pixel value when the shadow of dust is not projected on the pixel and the pixel value when the shadow of dust is projected are derived from the two captured images obtained by the imaging operation. However, if this method is adopted even when a plurality of dusts are present at close positions, different dusts may be imaged at different times on the same pixel, and the dusts cannot be distinguished. Therefore, in this case, it is desirable to reduce the moving pitch and increase the number of photographing.

  If the movement pitch is set to be the same as the pixel pitch, the size of the dust image corresponds to twice the size of the pixel, and the interval between adjacent dust images corresponds to twice the size of the pixel. The light transmittance at the position of each pixel can be calculated up to the adhesion state of the interval. Hereinafter, the reason will be described.

  Now, as shown in FIG. 18A, for example, a case is assumed where a dust image having the same size as a pixel is projected every other pixel in one direction. In FIG. 18A, the vertical direction indicates the size of the pixel value. As shown in FIG. 18A, before the cover glass 22 is moved, when the boundary between the two adjacent dust images and the boundary between the two adjacent pixels are projected so as to coincide with each other, When the cover glass 22 is moved by one pixel, a dust image and an image without a dust image are alternately projected on each pixel, and each pixel has a relatively large pixel value (output) and a small value. Pixel values (outputs) are output alternately.

  However, as shown in FIG. 17B, when each dust image is projected between two adjacent pixels before the cover glass 22 is moved, the cover glass 22 is moved by one pixel. At this time, a dust image (a dust image different from that before the movement) is projected between the two pixels at any timing.

  In this case, the image picked up by each pixel before and after the movement of the cover glass 22 is a mixed image of the dust image and the image not including the dust image, so that an image without dust is projected from each pixel. The pixel value when only the dust image is projected and the pixel value when only the dust image is projected cannot be obtained, and the intermediate pixel between the large pixel value and the small pixel value output from each pixel in the case shown in FIG. The value is output.

  Therefore, a pixel value is obtained when only the dust image is projected from each pixel regardless of the position of the dust image before the cover glass 22 is moved (the pixel is only the dust image). It is understood that the dust image needs to have a size corresponding to two pixels in order to generate a period during which the image is captured. In addition, regardless of the position of the dust image before the movement of the cover glass 22, a pixel value is obtained when an image that does not include the dust image is projected from each pixel (the pixel includes the dust image). It is understood that an interval corresponding to two pixels is necessary between two adjacent dust images in order to generate a period during which no image is captured. The light transmittance calculation unit 61 corresponds to the detection means in the claims.

  Returning to FIG. 6, the dust size detection unit 62 detects the size of the dust from the size of the dust image detected by the light transmittance calculation unit 61.

  As described above, the light receiving surface of the image pickup device 20 and the cover glass 22 are arranged apart from each other by a predetermined distance in the optical axis direction, and radial light is emitted from the auxiliary light irradiation unit 57. Therefore, the dust image projected on the light receiving surface of the image sensor 20 is larger than the actual dust size.

  Here, if the optical path of the incident light to the imaging unit 19 (the direction of the optical axis and the light beam) is the same during the light transmittance calculation process by the light transmittance calculation unit 61 and when the subject is photographed, the light transmittance. Since the size of the dust image projected onto the image sensor 20 during the calculation process and the size of the dust image projected onto the image sensor 20 during shooting are the same, the dust image detected during the light transmittance calculation process (light transmittance distribution) Can be used as it is, and a restoration process described later for removing the shadow of dust from the captured image can be performed.

  However, in the single-lens reflex digital camera 1 as in the present embodiment, the position of the aperture 43 and the shape of the lens differ depending on the type of the interchangeable lens 2, and depending on the aperture value set at the time of shooting. Since the aperture diameter changes, the light path of the incident light to the image pickup unit 19 (the direction of the optical axis and the light beam) and the size of the dust image are the same during the light transmittance calculation process and during the photographing. Often not.

  Since the subject light incident on each pixel at the time of photographing varies (it is not uniform (uniform) in each pixel), the incident light on each pixel is attenuated by dust on the cover glass 22. It cannot be determined whether or not. Therefore, the dust image included in the captured image cannot be identified from the captured image.

  Therefore, in the present embodiment, as shown in FIG. 19A, the distribution of the light transmittance calculated by the light transmittance calculation unit 61 (the size of the dust image projected on the image sensor 20 during the light transmittance calculation process). ) And the distance from the light emitting unit 58 to the cover glass 22 and the light receiving surface of the image pickup device 20, etc., as shown in FIG. 19B, the size of the dust is once calculated and shown in FIG. As shown, the size of the dust image projected onto the image sensor 20 during photographing is derived based on the dust size and photographing conditions such as the aperture value during photographing.

  As shown in FIG. 12, when it is assumed that it is disposed at a position facing the cover glass 22, which is optically equivalent to this actual arrangement position, as shown in FIG. When the distance from the part 58 to the cover glass 22 is Lg, and the distance from the light emitting point P of the light emitting part 58 to the light receiving surface of the image sensor 20 is Ls, the dust image projected on the image sensor 20 during the light transmittance calculation process Is Ls / Lg times the actual dust size.

  By the way, the size of the dust can be derived from the distribution of light transmittance at the surface position of the cover glass 22 to which the dust adheres. In order to derive the distribution of light transmittance at this surface position. In this embodiment, it is necessary to obtain the light transmittance at the position of each pixel in that state, assuming that the light receiving surface of the image sensor 20 is located at the surface position. It derives using the method. FIG. 20 is a diagram for explaining a method for deriving the light transmittance.

In FIG. 20, an arrow Q1 indicates pixel values d ₁ , d ₂ ,... Of each pixel when attention is paid only to a pixel column in the X-axis direction with the optical axis as the origin for simplification of explanation, and an arrow Q2 indicates The surface position for generating the pixel data of the pixel values d ₁ , d ₂ ,... When the light receiving surface of the image sensor 20 is assumed to be positioned at the surface position of the cover glass 22 to which dust is attached. .., The pixel values d ₁ ′, d ₂ ′,... Of pixel data output from each pixel of the image sensor 20 located at the surface position, and an arrow Q3 is a cover to which dust is attached. Assuming that the light receiving surface of the image sensor 20 is located at the surface position of the glass 22, pixel values d ₁ ″ and d _{2 of} pixel data output from each pixel of the image sensor 20 located at the surface position. ", ... are shown.

When the pixel values d ₁ ′, d ₂ ′,... Indicated by the arrow Q2 are calculated from the pixel values d ₁ , d ₂ ,... Indicated by the arrow Q1, the pixel values d ₁ , d ₂ ,. Can be calculated by multiplying Lg / Ls (= r).

Then, when calculating the pixel values d ₁ ″, d ₂ ″,... Shown by the arrow Q3 from the pixel values d ₁ ′, d ₂ ′,. . For example, assuming that r> 1/2, as shown in FIG. 20, a certain pixel g1 of the image sensor 20 located at the surface position has an entire image that generates the pixel value d ₁ ′ and the pixel value d ₂ ′. The pixel value d ₁ ″ of the pixel g1 is received from FIG.
d ₁ ″ = r × d ₁ + (1−r) × d ₂
For example, the pixel value d ₂ ″ of the pixel g2 is
d ₂ ″ = {r− (1−r)} × d ₂ + [1− {r− (1−r)}] × d ₃
It becomes.

  Thereby, it is possible to derive the light transmittance in each pixel of the image sensor 20 when it is assumed that the light receiving surface of the image sensor 20 is located at the surface position of the cover glass 22 to which dust is attached. As a result, the dust size can be detected using this light transmittance distribution.

  As described above, the dust image detected by the image sensor 20 is larger than the actual size of the dust adhering to the cover glass 22, so that the image data constituting the dust image at the position of the cover glass 22 is changed. In order to derive the image data, it is necessary to reduce the image data output from each pixel of the image sensor 20. However, since the image data is handled discretely, the pixel pitch cannot be continuously reduced. . Therefore, as described above, the reduced dust image data is converted into the original pixel pitch, and an interpolation method such as the bilinear method is employed for this conversion processing.

  In the present embodiment, radial light from one point light source is irradiated onto the cover glass 22 to form a dust image on the light receiving surface of the image sensor 20, and two point light sources are located at different positions. Since there is no shaded portion (outlined blur) due to only one point light source that occurs when arranged, the dust size can be accurately detected by the interpolation method described above. The dust size detection unit 62 corresponds to the derivation means in the claims.

  The dust removal control unit 63 detects the light transmittance calculated by the light transmittance calculation unit 61 when a predetermined number or more of pixels having a light transmittance equal to or less than a predetermined threshold exist, or is detected by the dust size detection unit 62. When the size of the dust is equal to or smaller than a predetermined threshold value, the operation of the dust removing unit 56 is controlled so as to remove the dust adhering to the cover glass 22.

  That is, as described above, the dust removal control unit 63 outputs a pulse-like drive signal to the vibration mechanism 23 in the dust removal unit 56, thereby causing the cover glass 22 to be rapidly displaced. Dust on the glass 22 is dropped.

  In general, when a uniform subject image such as gray is captured, the degree of decrease in pixel value that can be detected as unevenness is said to be about 3 to 5%, that is, the pixel value of the pixel is other pixels. When the value is about 3 to 5% lower than the value, the image picked up by the pixel is visually perceived as unevenness by the human eye. Therefore, the light transmittance used for determining whether or not dust removal processing is necessary by the dust removal control unit 63. The threshold value may be set within a range of 95 to 97% of the pixel value of the pixel not receiving the dust image.

  Further, the dust removal processing by the dust removal control unit 63 may be executed when there is at least one pixel having a light transmittance equal to or lower than the threshold, or pixels having a light transmittance equal to or lower than the threshold. A threshold value for the number may be set in advance, and may be executed when the number of pixels whose light transmittance is equal to or less than the threshold value is equal to or greater than the threshold value for the number of pixels. Furthermore, the time for causing the rapid displacement of the cover glass 22 may be set as appropriate.

  Further, since the inertial force acting on the dust due to the impact given by the vibration mechanism 23 is proportional to the mass of the dust, the light dust is unlikely to fall from the surface of the cover glass 22. Therefore, for example, when it is detected that small dust that is considered to be lightweight exists, an impact may be applied to the cover glass 22 a plurality of times.

  When the dust removal processing by the dust removal control unit 63 is completed, the light transmittance calculating unit 61 and the dust size detecting unit 62 execute the light transmittance calculating process and the dust size detecting process again, and the cover glass to which dust is attached The light transmittance of each pixel of the image pickup device 20 when the light receiving surface of the image pickup device 20 is assumed to be located at the surface position 22 is stored in the storage unit 65.

  The restoration processing unit 64 performs restoration processing (step # 13 shown in FIG. 9) that removes or suppresses a dust image (shadow of dust) from the captured image.

  First, as described above, the size of the dust image obtained when calculating the light transmittance by the light transmittance calculating unit 61 and the size of the dust image at the time of photographing are the same dust adhering to the cover glass 22. Usually does not match. At the time of calculating the light transmittance, since the light source is a point light source, the dust image projected on the image sensor 20 is an enlargement of the actual dust shape, but the blur as shown by the arrow T in FIG. There is no.

  On the other hand, at the time of shooting, a light beam having a certain width is guided from the aperture of the diaphragm 43 having a predetermined size, and since this light beam is not composed of parallel light, it is projected onto the image sensor 20. The dust image has an enlarged shape of the actual dust and has a blur as indicated by an arrow T in FIG.

  FIG. 21 is a diagram illustrating the relationship between the pixel position and the light transmittance at the time of photographing when the XZ section passing through the optical axis L of the photographing optical system 38 is viewed. It is assumed that the light emitted from the aperture of the diaphragm 43 during photographing is in a completely diffused state.

  As shown in FIG. 21, among the light rays that pass near one end P1 in the opening of the aperture 43, the point on the image sensor 22 where the light ray L1 that passes through one end of the dust M on the cover glass 22 reaches E1, and the dust A point on the image sensor 22 where the light beam L2 passing through the other end of M reaches E2 and one end of the dust M on the cover glass 22 among the light beams passing near the other end portion P2 in the opening of the stop 43. A point on the image sensor 22 at which the passing light beam L3 reaches E3, and a point on the image sensor 22 at which the light beam L4 passing through the other end of the dust M reaches E4.

  At this time, only the light beam that has passed through the dust M reaches the pixel located between the point E1 and the point E4, while the pixel located between the point E1 and the point E3 and between the point E4 and the point E2 In addition to the light beam that has passed through the dust M, there is a light beam that enters without being attenuated by the dust M, and this portion becomes the blur. The amount of light increases from point E1 to point E3 and from point E4 to point E2.

  Therefore, as shown in FIG. 21, the light transmittance at the position of the pixel located between the points E1 and E4 is the smallest (light transmittance s in FIG. 21), and from the point E1 to the point E3, Further, the light transmittance increases from the point E4 to the point E2, and the light transmittance at the position of the pixel located outside the points E2 and E3 is approximately 100%. The minimum light transmittance s is derived on the assumption that the light receiving surface of the image sensor 20 is located at the surface position of the cover glass 22 to which dust is attached. It is equivalent to.

  Next, a method for deriving a function indicating a change in light transmittance of a pixel located between the points E1 and E3 and between the points E4 and E2 will be described.

As shown in FIG. 21, the distance in the optical axis direction between the diaphragm 43 and the cover glass 22 is a, the distance in the optical axis direction between the cover glass 22 and the image sensor 20 is b, and one end P1 and dust at the opening of the diaphragm 43 The distance from the other end of M in FIG. 21 in the vertical direction (X-axis direction) is c, the diameter of the aperture of the aperture 43 is L, and the pixels aligned in the vertical direction (X-axis direction) in FIG. When the coordinate system having the origin corresponding to the position corresponding to the lower end P2 in the opening of 43 is set, the pixel position v corresponding to the point E2 and the pixel position u corresponding to the point E4 are:
v = L−c × {(a + b) / a}
u = (L−c) × {(a + b) / a}
It becomes.

Here, assuming that the light transmittance from the pixel position v to the pixel position u changes linearly, the light transmittance at an arbitrary pixel position x of the image sensor 20 is
100 when 0 ≦ x <v
When v ≦ x <u (x−1) × (100−s) / (v−u) +100
s when u ≦ x
It becomes.

  When dust is attached to the cover glass 22, light (subject light) from the photographing optical system 38 is considered to be attenuated by the dust, and the pixel when the subject light attenuated by the dust is received. It can be considered that the value is obtained by multiplying the pixel value when the subject light not attenuated by dust is received by the above-described light transmittance. Therefore, the pixel value when the subject light not attenuated by dust is received can be calculated by dividing the pixel value when the subject light attenuated by dust is divided by the above-described light transmittance. .

For example, as shown in FIG. 21, when the pixel position x ₁ is v ≦ x ₁ <u, the light transmittance at the pixel position x ₁ is (x ₁ −1) × (100−s) / (v− since the u) +100, when the pixel values of the image captured by the pixel the pixel position x ₁ is d, the pixel value when the pixel has subject light receiving no attenuation by dust,
d ÷ [(x ₁ −1) × (100−s) / (v−u) +100]
It becomes.

  As described above, the photographing conditions when the photographed image is photographed (including the aperture diameter of the diaphragm 43, the shape of the aperture of the diaphragm 43, the distance between the diaphragm 43 and the cover glass 22, the distance between the diaphragm 43 and the image sensor 20, etc.) And the light transmittance at each pixel of the image sensor 20 derived on the assumption that the light receiving surface of the image sensor 20 is located at the surface position of the cover glass 22 to which dust is attached. By detecting the included dust image (shadow of dust) and removing or suppressing the influence of the dust from the captured image, a beautiful captured image can be restored.

  As described above, in a state where the external light is blocked and the light emitting unit 58 is turned on, the imaging device 20 performs an imaging operation a plurality of times in synchronization with the movement of the cover glass 22 in the X-axis direction. The light transmittance obtained from the light transmittance for each pixel is calculated by dividing the pixel value obtained at each time by a pixel value that is significantly smaller than the other pixel values by the other pixel value. A dust image projected on the image sensor 20 is detected from the distribution, and interpolation processing such as a bilinear method is performed using the dust image and the distances Lg and Ls from the light emitting unit 58 to the cover glass 22 and the light receiving surface of the image sensor 20. Thus, when it is assumed that the light receiving surface of the image pickup device 20 is located at the surface position of the cover glass 22, an image of the dust (same size image) obtained from the image pickup device 20 is derived, and the image of each pixel is Because the restoration process was done It is possible to obtain a no or less beautiful photographic image of the impact of the dust.

  In addition to the said embodiment, it can replace with the said embodiment and the deformation | transformation form demonstrated to the following form [1]-[15] is also employable for this invention.

  [1] In the above embodiment, a light source 58 that can be regarded as a point light source is used. However, when the light source is relatively large, the light emitted from the light source is converted into point light using a stop such as a pinhole. The point light may be guided to the lens 59 and diffused.

  [2] When the influence of dust is large and the degree of decrease in the light transmittance due to the dust is large, the pixel value of the pixel that captured the dust image becomes very small. There is a possibility that the captured image cannot be restored. Therefore, when the influence of dust is large (when the light transmittance is extremely small), the following processing is recommended.

  First, when a shooting instruction is issued by fully pressing the shutter button 4, the overall control unit 37 causes the image sensor 20 to perform an exposure operation for a predetermined time based on a predetermined exposure control value, and this exposure operation. In parallel, the cover glass 22 is moved in a predetermined direction (for example, the X-axis direction). The moving amount of the cover glass 22 moved during the predetermined time may be 1 mm, for example, or may be equivalent to several pixels.

  When the cover glass 22 is moved during exposure of the image sensor 20, pixels having a period during which the dust image passes during the exposure period are generated among the pixels of the image sensor 20. The pixel value of this pixel is a value corresponding to the sum of the amount of received light during a period when the dust image has passed and the amount of received light during the other period (a period during which no dust image has passed). Note that an image obtained by this exposure operation is an image in which shadows due to dust extending thinly in the moving direction of the cover glass 22 are mixed.

  On the other hand, the following arithmetic processing is performed on the light transmittance at each pixel position calculated by the light transmittance calculator 61.

First, the overall control unit 37 calculates the movement amount of the cover glass 22 from the movement speed and exposure time of the cover glass 22, and converts this movement amount into the number of pixels. This converted number of pixels is n. The overall control unit 37 divides the decrease in light transmittance expressed as a percentage by the converted pixel number n, and moves (shifts) this divided value to n pixels one by one in the horizontal direction. Each distribution is obtained, and for each pixel, all division values relating to the pixel obtained for each number of moving pixels are added. Then, the obtained addition value is converted into a decimal. If the added value obtained by converting the decimal of the pixel G _N and P _N, divides the pixel value of each pixel in the captured image by (1-P _N).

  This series of processing will be described by applying specific numerical values. For example, ten pixels G1 to G10 belonging to a certain pixel row extending in the horizontal direction are positioned at positions (initial positions) before the cover glass 22 is moved. It is assumed that the light transmittance distribution at the time is as shown in FIG.

  That is, as shown in FIG. 22B, when the cover glass 22 is located at the initial position, the light transmittance of the pixels G1, G2, G8 to G10 is 100, the light transmittance of the pixel G3 is 80, and the pixel G4 , The light transmittance of the pixel G5 is 50, the light transmittance of the pixel G6 is 70, and the light transmittance of the pixel G7 is 90.

  In this case, as shown in FIG. 22B, the decrease in the light transmittance due to the influence of dust is 0 for the pixels G1, G2, G8 to G10, 20 for the pixel G3, 60 for the pixel G4, The pixel G5 is 50, the pixel G6 is 30, and the pixel G7 is 10.

  If the converted pixel number n obtained from the movement amount of the cover glass 22 is 10 (the cover glass 22 is moved by a movement amount corresponding to 10 pixels in the horizontal direction), the light transmission of each pixel The rate decrease is divided by this converted pixel count of 10. The division value obtained for each pixel is indicated by an arrow (1) in FIG.

  Next, this divided value is moved up to 10 pixels one by one in the arrangement direction of the pixels G1 to G10 (the horizontal direction), and a divided value for each pixel in each moving pixel number is obtained. For example, a distribution obtained by moving the division value for each pixel indicated by arrow (1) in FIG. 22B by one pixel is indicated by arrow (2) in FIG. 22B, and for example, the arrow in FIG. A distribution obtained by moving the division value for each pixel indicated by (1) by two pixels is indicated by an arrow (3) in FIG.

  In this way, for each pixel, the distribution of the divided values moved up to the number of converted pixels of 10 pixels is obtained, and each divided value is added in each of the pixels G1 to G10. An added value for each of the pixels G1 to G10 obtained by this addition processing is indicated by an arrow (4) in FIG. Further, this added value is converted into a decimal, and (1-added value) is calculated for each pixel G1 to G10, and each pixel value of the photographed image at the position of each pixel G1 to G10 corresponds to (1-added value). ).

When the pixel value of each pixel G1~G10 in the captured image obtained by performing the imaging operation while moving the cover glass 22 as described above and d ₁ to d _10, as shown in FIG. 22 (c) to, for example, for the pixel G5 divides the pixel value d ₅ in (1-0.13 (= 0.87)).

  With this processing, as indicated by the arrow (5) in FIG. 22, the pixel values of the pixels G1 to G10 in the captured image obtained by performing the imaging operation while moving the cover glass 22 are indicated by the arrow (6). As shown in the figure, the pixel values of the pixels G3 to G8 whose pixel values have been greatly reduced due to the influence of dust can be increased, and the positions of the pixels G1, G2, G9, and G10 that have been affected by the dust. Can be smoothed with respect to the image.

  As a result, even when dust having very low light transmittance is attached to the cover glass 22, the dust image in the photographed image becomes inconspicuous, and a beautiful photographed image in which the influence of dust is suppressed can be obtained.

  [3] As described above, dust that cannot be removed even if the dust removal operation is performed (does not fall) adheres to the cover glass 22 with a relatively large adhesion force, and thus drops depending on normal use of the digital camera 1. Although it is considered that the possibility is low, such dust is covered with the cover glass due to vibration applied to the digital camera 1 when the digital camera 1 is transported or vibration applied to the digital camera 1 due to falling while the digital camera 1 is in use. There is a possibility of falling from the surface of 22.

  At this time, when the time of photographing has elapsed from the time of calculating the light transmittance, the dust image stored in the digital camera 1 may not match the actual dust adhesion state. In this case, the restoration process is performed even for the image of the pixel that does not need to be restored (the image of the pixel that has been affected by the dust).

  As a result, as in the first embodiment, the pixel value when the subject light attenuated by dust is received is divided by the light transmittance, which corresponds to, for example, the portion of the dust image stored in the digital camera 1. There is a possibility that the pixel value to be processed becomes larger than the pixel value of the surrounding image, and the image corresponding to the dust image portion becomes brighter than the surrounding image, so that the image is not faithful to the subject image.

  Therefore, in the case of adopting a configuration in which the cover glass 22 is moved in the horizontal direction during the exposure operation of the image sensor 20 as in the modification [2], the following processing is performed using this configuration. By performing the above, the latest dust image can be detected.

  FIG. 23A shows an example of a photographed image obtained by moving the cover glass 22 in a predetermined direction (X-axis direction in FIG. 23) during the exposure operation of the image sensor 20, and FIG. ) Shows an example of a dust image stored in the storage unit 54.

  Assuming that, for example, a photographed image shown in FIG. 23A is obtained by performing a photographing operation in accordance with an instruction from the photographer, the overall control unit 37 differentiates the photographed image and performs FIG. 23C. The edge of the image is extracted as shown in FIG.

  Then, the overall control unit 37 extracts, as a dust image candidate, an image in which the extending direction of the edge coincides with the moving direction of the cover glass 22 and has a length equal to or longer than the moving amount of the cover glass 22. . For example, in FIG. 23C, it is assumed that the edges E1 to E5 are extracted as dust image candidates. As a method for determining the directionality of an image, for example, a well-known technique such as a Hough transform that projects a point on a coordinate onto a straight line can be employed.

  Next, the overall control unit 37 compares the stored image of dust shown in FIG. 23B with the edges shown in FIG. 23C, and the stored images of dust M1 to M5 correspond to the respective edges. It is judged whether it is a thing. For example, since the position of the edge E1 in the captured image in FIG. 23C includes the position in the captured image of the stored image M1, the edge E1 corresponds to the stored image M1 shown in FIG. It is judged. Similarly, the edges E2 and E3 in FIG. 23C correspond to the stored images M2 and M3 shown in FIG. 23B, while the edges corresponding to the stored images M4 and M5 are shown in FIG. It is determined that it does not exist in the captured image shown in c).

  Therefore, the restoration processing is performed on the dust storage images M1 to M3 in the photographed image, while the dust storage images M4 and M5 are stored between the calculation time of the light transmittance and the photographing time. Since it is considered that the dust corresponding to the stored images M4 and M5 has fallen from the cover glass 22 (natural fall), the restoration process is not performed.

  In FIG. 23C, since edges E4 ′ and E5 ′ corresponding to dust images not included in the stored image are newly generated, the current shooting time and the latest dust image storage time are not detected. It is considered that dust newly adhered to the cover glass 22 during the period. As described above, when it is determined that new dust has adhered to the cover glass 22, the overall control unit 37 automatically detects dust (operation for calculating light transmittance at the position of each pixel) after the photographing is completed. ) And the latest dust image is stored in the storage unit 54.

  Thereby, the restoration process is executed only for the image of the pixel that needs to be restored, and the influence of dust newly attached to the cover glass 22 can be removed or suppressed by the restoration process. An image faithful to the subject image can be obtained.

  [4] In the modified embodiments [2] and [3], the amount of movement of the cover glass 22 at the time of shooting is constant, but it is changed according to the state of dust adhesion (including the amount of dust). Also good. Assuming that the decrease in light transmittance of subject light due to dust is constant, as shown in FIG. 24A, the decrease in light transmittance is D, the dust adhesion length is W pixels, and a cover at the time of shooting The amount of movement of the glass 22 is M pixels. For simplification of explanation, it is assumed that the dust image moves to adjacent pixels stepwise.

  Each portion of the cover glass 22 has a total of (M + 1) pieces of an initial position before the movement is started and M step positions when the movement is stepped to M pixels during the movement period. Since the pixel value decrease corresponding to the light transmittance decrease D is evenly divided at each position, each portion of the cover glass 22 is located at each position. The decrease in light transmittance (division decrease) at the position of each pixel when positioned is D / (M + 1).

  The decrease in light transmittance at the position of each pixel is the sum of the decrease in light transmittance (division decrease) at the position of the pixel when each portion of the cover glass 22 is positioned at each position. Become. Here, when calculating the sum of the light transmission division reduction at the position of each pixel, the maximum value among the number of steps corresponding to each pixel (corresponding to the number of positions that each part of the cover glass 22 can take) is Depending on the relationship between the amount of movement M of the cover glass 22 and the adhesion length W of dust.

  FIG. 24B is a diagram illustrating a decrease in light transmittance at each pixel position when each portion of the cover glass 22 is positioned at each position. As indicated by an arrow A in FIG. 24B, in the range where the movement amount M of the cover glass 22 is up to (W−2), the maximum value of the number of steps is (M + 1). It can be seen that when the movement amount M is (W-1) or more, the maximum number of steps is W.

Therefore, the maximum value D ′ of the sum of the decrease in light transmittance is
D ′ = (M + 1) × {D / (M + 1)} (when M ≦ W−2)
D ′ = W × {D / (M + 1)} (when M ≧ W−1)
It becomes.

  Therefore, as described above, when an image of a uniform subject such as gray is captured, it is said that the degree of decrease in pixel value that can be detected as unevenness is about 3 to 5%. And the dust size detection unit 62 determine the light transmittance decrease D and the dust adhesion length W, and the movement amount M of the cover glass 22 so that the maximum value D ′ is 3 to 5 (%). Therefore, it is possible to make the shadow of dust in the captured image inconspicuous without performing the restoration process. It should be noted that if the restoration process is further performed, an even more beautiful captured image can be generated.

  [5] The dust detection operation and restoration process may be automatically executed when the digital camera 1 is turned on, immediately after the interchangeable lens is mounted, or whenever a predetermined number of images are shot. Further, the dust removal operation may be automatically executed in conjunction with the dust detection operation. As a result, it is possible to stably generate a beautiful captured image with little or no influence of dust, and it is unnecessary for the photographer to instruct the start of the dust detection operation and the dust removal operation. This can contribute to improving the operability of the digital camera 1.

  Note that when the digital camera 1 is configured to automatically start the dust detection operation, the dust removal operation, and the restoration processing, the dust detection operation, the dust removal operation, and the restoration processing are selected. It is also possible to configure so that an execution instruction can be given.

  [6] If a large amount of dust remains or the size of the dust remains large even when the dust removal operation is performed, a clean image may not be obtained even if the restoration process described above is executed. In such a case, a predetermined threshold is set for the size and pixel value of the remaining dust image, and when the size or pixel value of the remaining dust image exceeds this threshold, the photographing operation by the photographer is prohibited. A configuration may be adopted in which an expert is requested to request repair or service (inspection).

  [7] In the first embodiment, the dust detection operation is performed and the dust removal operation is performed when the dust is detected. However, when an instruction from the user of the digital camera 1 is given, It is also possible to perform the dust removal operation immediately without performing the detection operation, and then perform the dust detection operation.

  [8] The movement mode (movement direction) of the cover glass 22 is not limited to the horizontal direction (X-axis direction in FIG. 4), and for example, in the XY plane of FIG. You may move to the diagonal direction which cross | intersects both Y-axis, or you may move so that various figures, such as a circle, a rectangle, or a polygon, may be drawn.

  The direction of the inertial force in which the dust tends to fall differs depending on the relationship between the dust adhering portion in contact with the cover glass 22 and the center of gravity of the dust, the shape of the dust, and the like. Therefore, if the cover glass 22 is moved so that an inertial force acts in a plurality of directions such as a rectangle or a polygon, the possibility of dust falling from the cover glass 22 can be increased.

  Also, in the natural world, images that are characteristic of boundaries (for example, horizon, horizontal lines, building walls, tree trunks, etc.) have many components in the horizontal and vertical directions, and few in the diagonal and circular components. It has been broken. Therefore, in the modified embodiment [3] in which the cover glass 22 is moved and the restoration process is performed, when the cover glass 22 is moved to draw various figures such as a circle, a rectangle, or a polygon as described above. Even if it is determined that the detected circular or polygonal graphic image is a dust image, there is a low possibility that the determination is incorrect.

  As a result, the dust can be detected by simply moving the cover glass 22 so as to draw various figures such as a circle, a rectangle, or a polygon, and determining the shape of the image obtained at that time. It is possible to easily detect the deterioration of the captured image in the processing.

  [9] The detected dust image may be displayed on the LCD 5. In this case, the light transmittance distribution may be displayed on the LCD 5, or a shadow due to dust may be displayed in a predetermined color (for example, a relatively conspicuous red color or the like) superimposed on the photographed image. .

  Further, the light transmittance, the dust adhesion area, and the like may be digitized to predict the degree of image degradation and notify the photographer. Accordingly, since the photographer can grasp the dust adhesion state, it is possible to determine the necessity of dust removal, image restoration processing, or cleaning / service request / re-shooting of the camera body 1a. .

  [10] The restoration process is not limited to the one executed in the digital camera 1 and may be executed by an external electronic device such as a personal computer.

  In this case, first, the digital camera 1 stores, for example, the storage unit 54 in association with the photographed image and the recent light transmittance or the light transmittance detected immediately after the photographing at the photographing time point. Further, when the cover glass 22 is moved at the time of photographing, information such as the moving amount and moving speed is also stored in the storage unit 54 and the like.

  When the storage unit 54 is attached to the personal computer, the personal computer reads the captured image from the storage unit 54 and performs the restoration process according to a predetermined program. As a result, the operator can determine whether or not the restoration process is necessary while checking the degree of deterioration of the captured image due to dust on a screen larger than the LCD 5.

  [11] In the first embodiment, when the dust removal operation on the cover glass 22 is performed, the vibration amplitude of the cover glass 22 is substantially equal to the amount of expansion and contraction in the stacking direction of the piezoelectric elements. In the case where it is desired to vibrate the cover glass 22 with an amplitude value larger than this amplitude while keeping the drive signal output to the mechanism 23 constant, for example, a structure as shown in FIG. 25 may be adopted.

  As shown in FIG. 25 (a), in this embodiment, the vibration mechanism 23 (piezoelectric element) is in direct contact with the cover glass 22 as in the first embodiment. However, the expansion / contraction motion (vibration) of the vibration mechanism 23 is indirectly transmitted to the cover glass 22 using the principle of the lever.

  The excitation mechanism 23 ′ of this embodiment includes a laminated piezoelectric body 66 (hereinafter simply referred to as a piezoelectric body 66) having the same configuration as the excitation mechanism 23 of the first embodiment, and an arm member 67 described later. The piezoelectric body 66 has one end portion so that an axis parallel to the stacking direction of the piezoelectric elements is parallel to the surface of the cover glass 22 or a plane parallel to the surface. It is installed in a fixed state.

  The arm member 67 is a member for indirectly transmitting the expansion / contraction motion (vibration) of the piezoelectric body 66 to the cover glass 22 using the principle of an insulator, and includes a relatively long base portion 67a and the base portion 67a. It is comprised in the "U" shape which has the protrusion parts 67b and 67c projected from each edge part. Further, the arm member 67 has a tip end of one projecting portion 67b in contact with the other end portion of the vibration mechanism 23 and a tip end of the other projecting portion 67c in contact with one end side surface of the cover glass 22, and a base portion 67a. Is rotatably supported by a rotating shaft 68 provided at a position deviated from the center position in the length direction toward the excitation mechanism 23 side.

  With this configuration, as shown in FIG. 25 (b), when the arm member 67 rotates about the rotation shaft 68, the displacement amount X2 of the protrusion 67c on the side in contact with one side surface of the cover glass 22 is excited. Since the displacement amount X1 of the projecting portion 67b on the side contacting the one end portion of the mechanism 23 is larger (X2> X1), the cover glass 22 can be vibrated mechanically larger than the vibration amplitude of the piezoelectric body 66.

  The amplitude amplification factor X2 / X1 is determined according to the ratio H2 / H1 of the distances H1 and H2 from the position of the rotating shaft 68 to the protrusions 67b and 67c of the arm member 67. It may be set based on the amount of displacement of the glass 22.

  [12] The configuration for applying and driving the impact to the cover glass 22 for removing dust is not limited to the configuration using the piezoelectric element as in the first embodiment or the modified embodiment [11]. For example, it may have the following configuration. FIG. 26 is a diagram illustrating an example of another configuration in which the cover glass 22 is driven and vibrated.

  As shown in FIG. 26, the vibration mechanism 23 ″ of the cover glass 22 in the present embodiment is configured to include a motor 68 and an eccentric cam 69, and in the vicinity of one side surface of the cover glass 22 in the X-axis direction. It is arranged.

  The eccentric cam 69 is connected to a drive shaft 68a of the motor 68 at a predetermined portion, and rotates with the connecting portion as a rotation center by the operation of the motor 68. The eccentric cam 69 is a member having a shape in which the relationship between the distances between the respective portions of the outer peripheral surface and the rotation center O increases continuously in one circumferential direction, and the outer peripheral surface is the cover glass 22. It is installed in a state in which it is in contact with the one end side surface.

  A coil spring 70 having a function as an urging means for urging the cover glass 22 toward the eccentric cam 69 is attached to the other side surface of the cover glass 22. The one end side surface of the glass 22 is in sliding contact with the outer peripheral surface of the eccentric cam 69.

  FIG. 27 is a diagram showing a state of movement of the cover glass 22 in accordance with the rotational operation of the eccentric cam 69. FIGS. FIG. 27B is a graph showing a change in the position of the cover glass 22 as viewed from the upper side of FIG. 26, and FIG. 27B is a graph showing the change in the position of the cover glass 22 according to the position of the eccentric cam 69 in contact therewith. Yes, the horizontal axis is time t, and the vertical axis is the X-axis direction of the cover glass 22 relative to the position of the cover glass 22 in FIG. 27 (a-3) (the right side of FIG. 27 (a) is positive). Position.

  As shown in FIGS. 27 (a-1) to (a-4), among the portions on the outer periphery of the eccentric cam 69, the portion having the smallest distance from the rotation center O is H1, and the distance from the rotation center O is the same. Assuming that the portion with the largest H2 is H2, as shown in FIG. 27 (a-1), when the portion H1 of the eccentric cam 69 contacts the one end side surface of the cover glass 22 (time t1 in FIG. 27 (b)). The cover glass 22 is positioned on the rightmost side in FIG. 27A. When the eccentric cam 69 rotates counterclockwise as viewed from above, the cover glass 22 is in contact with the one end side surface of the cover glass 22. Since the distance between the portion of the cam 69 and the rotation center O increases, the cover glass 22 moves to the left (X-axis negative direction) of FIG. 27A as shown in FIG. . The state shown in FIG. 27A-2 shows one state between times t1 and t2 in FIG.

  Further, when the eccentric cam 69 further rotates and the portion H2 of the eccentric cam 69 that makes the greatest distance from the rotation center O contacts the one end side surface of the cover glass 22, as shown in FIG. (Time t2 in FIG. 27 (b)), the cover glass 22 is located on the leftmost side of the possible positions, and the eccentric cam 69 is further rotated. As shown in FIG. When the portion H2 of the cam 69 moves away from the one end side surface of the cover glass 22 (time t3 in FIG. 27B), the diameter of the portion of the eccentric cam 69 facing the one end side surface of the cover glass 22 changes abruptly (portion Due to the step between H1 and H2, the cover glass 22 moves to the right side of FIG. 27 (a) in a short time by the biasing force of the coil spring 70, resulting in the state of FIG. 27 (a-1) ( Time t4 in FIG.

  According to this configuration, there is a period during which the cover glass 22 is moved in the X-axis direction at a relatively low speed and a period during which the cover glass 22 is moved in the X-axis direction at a very high speed. Therefore, also in the vibration mechanism 23 ′ of the present embodiment, the impact applied to the cover glass 22 to perform the relatively low-speed movement of the cover glass 22 performed at the time of photographing and the removal of dust adhering to the cover glass 22. Both movement (displacement) can be realized.

  [13] In the single-lens reflex digital camera 1, in order to facilitate the calculation processing of the shape and characteristics of the lens or the light transmittance of each aperture replacement lens 2, the optical of the light emitting unit 58 with respect to the light receiving surface of the image sensor 20 The position may be made to substantially coincide with the optical position of the diaphragm of the standard interchangeable lens 2 that is frequently used with respect to the light receiving surface.

  [14] The object of dust adhering into the camera body 1A, which is the subject of the present invention, is not limited to the cover glass 22, but is exposed to the outside when the interchangeable lens 2 is removed from the camera body 1A. This includes all members and members disposed on the optical path between the imaging optical system 38 and the image sensor 20.

  For example, an interference film that removes wavelength components in the near-infrared region of subject light, an infrared cut filter that uses a dye that absorbs light, and a high-cut filter that removes frequency components above a predetermined amount from subject light using birefringence Etc.

  [15] When detecting the size or the like of the dust adhering to the cover glass 22, the position of the light emitting unit 58 that irradiates the cover glass 22 with light and the lens 59 that diffuses the light from the light emitting unit 58 are as follows. When there is a space behind the lens mount 71 of the camera body 1A to which the interchangeable lens 2 is attached, for example, as shown in FIG. 28, the position is not limited to the position in the first embodiment. It may be arranged.

  Accordingly, since the light emitting unit 58 and the lens 59 are opposed to the cover glass 22, it is not necessary to refract the irradiation light diffused from the lens 59, and the small mirror 60 provided in the first embodiment is not necessary. Become.

  In this case, since the auxiliary light is applied to the cover glass 22 from a direction (an oblique direction) different from the optical axis of the photographing optical system 38, the size and detection position of dust are different from those at the time of photographing, but the light emitting unit 58 The dust image when the auxiliary light is irradiated is based on the distance from the cover glass 22 or the shift between the optical axis of the auxiliary light output from the light emitting unit 58 and the optical axis of the photographing optical system 38. It is possible to correct the dust image when auxiliary light is irradiated on the cover glass 22 in the optical axis direction of the photographing optical system 38 from the position of the diaphragm 43.

  Also, as shown in FIG. 29A, when the light emitting portion 58 and the lens 59 are provided at two positions on the left and right behind the lens mount 71, as will be described below, the optical axis direction (Z axis shown in FIG. 4). It is also possible to detect the position of dust in the direction.

  FIGS. 29B and 29C are diagrams for explaining a method of detecting the position of dust in the optical axis direction when the light emitting portions 58 and the like are provided at two positions on the left and right behind the lens mount 71. FIG. is there. In the present embodiment, the distances in the optical axis direction between the light emitting portion 58L and the light emitting portion 58R and the dust are the same, and not only the cover glass 22 but also filters such as a high cut filter are used for the cover glass. Suppose that it is arrange | positioned with respect to 22 in the optical axis direction via predetermined distance.

  As shown in FIG. 29A, the overall control unit 37 turns on the light emitting unit 58L and the light emitting unit 58R sequentially (alternatively), and causes the image sensor 20 to perform an imaging operation at the time of each lighting. As shown in FIG. 29B, dust images included in the image obtained by this imaging operation appear at different positions in the left-right direction. The upper diagram in FIG. 29B shows a captured image when the light emitting unit 58L is turned on and the imaging operation is performed, and the lower diagram shows that the light emitting unit 58R is lit and the imaging operation is performed. The photographed image is shown.

Then, the overall control unit 37 detects dust images having the same size and outline from both the captured images, and as shown in FIG. 29 (b), the gravity center positions G _L , G _R , And the distance r between the center of gravity positions G _L and G _R is calculated. Here, the distance r between the center of gravity positions G _L and G _R is proportional to the distance from the light receiving surface of the image sensor 20 to the dust in the optical axis direction (one-to-one) based on the principle of triangulation, which is a well-known technique. In the corresponding relationship).

In FIG. 29C, the cover glass 22 is located at a position separated from the light receiving surface of the image sensor 20 by a distance X1 in the optical axis direction, and the distance X2 (<X1) from the light receiving surface of the image sensor 20 in the optical axis direction. When the high-cut filter 72 is disposed at a separated position, dust M1 is attached on the cover glass 22, and dust M2 is attached on the high-cut filter 72, when the light emitting unit 58L is turned on and an imaging operation is performed. The center-of-gravity position G _L1 of the image of the dust M1 included in the obtained captured image and the center-of-gravity position G _R1 of the image of the dust M1 included in the captured image obtained when the imaging operation is performed with the light emitting unit 58R turned on. And the gravity center position G _L2 of the image of the dust M2 included in the captured image obtained when the light emitting unit 58L is turned on and the imaging operation is performed, and obtained when the imaging operation is performed with the light emitting unit 58R turned on. Be Indicates the gravity center position G _R2 of the image of the dust M2 contained in the shadow image.

As described above, the light emitting unit 58L and the light emitting unit 58R are sequentially turned on, and the interval between the gravity center positions of the respective dust images included in the captured images obtained at the time of lighting is determined by the image sensor in the optical axis direction. Since there is a one-to-one correspondence with the distance from the light receiving surface 20 to the dust, the distance r ₁ between the center of gravity positions G _L1 and G _{R1 is} the distance in the optical axis direction between the image sensor 20 and the cover glass 22. Further, the distance r ₂ between the gravity center positions G _L2 and G _R2 corresponds to the distance X2 between the image sensor 20 and the high cut filter 72 in the optical axis direction.

Accordingly, the light emitting unit 58L and the light emitting unit 58R are sequentially turned on, and regarding the captured images obtained when the imaging device 20 performs the imaging operation at the time of each lighting, both dust images included in the captured images. If the distance between the center of gravity positions is r ₁ , for example, it can be determined that the dust forming the dust image is attached to the cover glass 22, and the both dust images included in each captured image. If the distance between the center of gravity positions is r ₂ , for example, it can be determined that the dust forming the dust image is attached on the high-cut filter 72, and further, both dust images included in the captured image If the distance between the center of gravity positions of the _two is neither r ₁ nor r ₂ , it can be determined that dust is attached to the attached object other than the cover glass 22 and the high cut filter 72.

  Thus, by providing a plurality of light emitting points on a surface parallel to the light receiving surface of the image sensor 20, it is possible to detect the position of dust in the optical axis direction (Z-axis direction shown in FIG. 4). A predetermined treatment method can be selected according to the object to which dust is attached.

It is a front view which shows the structure of the digital camera which concerns on 1st Embodiment of an imaging device. It is a rear view which shows the structure of a digital camera. It is a figure which shows the internal structure of a digital camera. It is a disassembled perspective view which shows the structure of an imaging unit. (A) is a graph showing a waveform of a sine wave drive signal applied to the vibration mechanism and a change in acceleration when this sine wave drive signal is applied; It is a graph which shows the change of the acceleration at the time of applying the waveform of the drive signal of the pulse wave to apply, and this pulse wave drive signal. It is a block diagram which shows the electrical structure of the whole digital camera in the state by which the interchangeable lens was attached to the camera main body. It is a perspective view which shows the structure of an auxiliary light irradiation part. It is a flowchart which shows a series of processes regarding the dust adhering to a cover glass performed by the whole control part. It is a flowchart which shows a series of processes regarding the dust adhering to a cover glass performed by the whole control part. It is a graph which shows the pixel value of the pixel which belongs to a certain pixel row located in a line with the X-axis direction in this image pick-up element, when a cover glass is moved and image pick-up operation of an image pick-up element is performed at fixed time intervals. It is a perspective view which shows the projection state of this dust with respect to an image sensor, when dust has adhered to the surface of a cover glass. It is a side view showing the projection state of the dust to the image sensor, when dust adheres to the surface of the cover glass. It is a graph which shows an example of distribution of the light transmittance in the position of each pixel which belongs to a certain pixel row located in a line with the X-axis in an image sensor. It is a figure which shows distribution of the light transmittance about each pixel which belongs to a certain pixel row lined up in the X-axis direction in an image sensor. It is a figure for demonstrating the interpolation process for obtaining the transmittance | permeability of the light of R (red), G (green), and B (blue) in the position of each pixel. It is a figure for demonstrating the method to derive | lead-out the pixel value of the missing color component by the interpolation process using the pixel value of the surrounding pixel. It is a figure which shows distribution of the light transmittance of each color component in the position of each pixel obtained by the interpolation process. When the movement pitch of the cover glass is the same as the pixel pitch, the dust image size corresponds to twice the pixel size, and the interval between adjacent dust images corresponds to twice the pixel size. It is a figure for demonstrating the reason which can calculate the light transmittance in the position of each pixel to the adhesion state of a space | interval. It is a figure for demonstrating the method of deriving the size of the dust image projected on an image sensor at the time of imaging | photography. It is a figure for demonstrating the method to derive | lead-out the light transmittance distribution in the surface position of a cover glass. It is a figure which shows the relationship between the pixel position at the time of imaging | photography, and the light transmittance in the case of seeing the XZ cross section which passes along the optical axis of an imaging optical system. It is a figure which shows an example of distribution of the light transmittance when a cover glass is located in an initial position about ten pixels G1-G10 which belong to a certain pixel column extended in a horizontal direction. (A) shows an example of a photographed image obtained by moving the cover glass in a predetermined direction during the exposure operation of the image sensor, and (b) shows an example of a dust image stored in the storage unit. Is shown. It is a figure for demonstrating the calculation method of the light transmittance in the case of changing the moving amount | distance of the cover glass at the time of imaging | photography according to the adhesion state (including the amount of dust) of dust. It is a figure which shows an example of the structure for vibrating a cover glass with an amplitude value larger than the amplitude of the vibration in the lamination direction of a piezoelectric element, with the drive signal output to a vibration mechanism kept constant. It is a figure which shows an example of the other form of the structure which drives and vibrates a cover glass. It is a figure which shows the state of a movement of the cover glass according to rotation operation | movement of an eccentric cam. It is a figure which shows the other arrangement | positioning form of the lens which diffuses the light from the light emission part which irradiates light to a cover glass, and this light emission part. It is a figure for demonstrating the detection method of the structure which provided the light emission part and the lens in two places right and left behind a lens mount, and the position of a dust in an optical axis direction.

Explanation of symbols

1 Digital Camera 1A Camera Body 2 Interchangeable Lens (Lens Unit)
6a Dust removal button 19 Imaging unit 20 Imaging device 21 Package 22 Cover glass 23 Exciting mechanism 24 Pressure contact member 26 Capture member 38 Imaging optical system 56 Dust removal unit 57 Auxiliary light irradiation unit 58 Light emitting unit 59 Lens 60 Small mirror 61 Light transmittance Calculation unit 62 Dust size detection unit 63 Dust removal control unit 64 Restoration processing unit 65 Storage unit

Claims (10)

Dust adhering to a dust adhering target disposed on an optical path between an imaging optical system that forms an optical image of a subject and an imaging device in which an imaging surface is disposed on the imaging surface of the imaging optical system. A dust detection device for detecting,
A light irradiating means for irradiating the dust adhering object and the image sensor;
Driving means for moving the dust adhering target in a predetermined direction relative to the image sensor;
Control that causes the image pickup device to perform an image pickup operation a plurality of times while moving the dust adhering target object to the drive means in a state where the external light is blocked and the light irradiation means emits light substantially uniformly. Means,
Detecting means for comparing a plurality of captured images obtained by the imaging operation and detecting an image of dust contained in the captured images;
A dust detection apparatus comprising:   Using the image of the dust detected by the detection means and the distance in the optical axis direction from the light irradiation means to the dust adhesion target object and the image sensor, the dust attached to the dust adhesion target object, etc. The dust detection apparatus according to claim 1, further comprising derivation means for deriving a double image.   The detection means includes a first pixel value when a dust image is projected from the plurality of captured images, and a first pixel value when no dust image is projected from the plurality of captured images, for each pixel position of the image sensor. 2 is derived, and the transmittance of the irradiation light at the position of the pixel is calculated using the first and second pixel values, and the transmission obtained by the transmittance calculated for the position of each pixel. The dust detection apparatus according to claim 1, wherein an image of the dust is detected using a rate distribution. Dust adhering to a dust adhering object disposed on an optical path between an imaging optical system that forms an optical image of a subject and an imaging device in which an imaging surface is arranged on the imaging surface of the imaging optical system. A dust detection device for detecting,
A light irradiating means for irradiating the dust adhering object and the image sensor;
Control means for causing the image sensor to perform an imaging operation in a state where external light is blocked and light is irradiated by the light irradiation means;
Storage means for storing a predetermined image in advance;
A dust detection apparatus comprising: a detection unit that compares a captured image obtained by the imaging operation with the predetermined image and detects an image of dust contained in the captured image.   Using the image of the dust detected by the detection means and the distance in the optical axis direction from the light irradiation means to the dust adhesion target object and the image sensor, the dust attached to the dust adhesion target object, etc. The dust detection apparatus according to claim 4, further comprising derivation means for deriving a double image. A lens unit having a photographing optical system that forms a light image of a subject;
An apparatus main body including an imaging element in which an imaging surface is disposed on an imaging surface of the photographing optical system;
An imaging apparatus in which the lens unit is configured to be detachable from the apparatus main body,
An imaging device comprising the dust detection device according to claim 1. Dust adhering to a dust adhering object disposed on an optical path between an imaging optical system that forms an optical image of a subject and an imaging device in which an imaging surface is arranged on the imaging surface of the imaging optical system. A dust detection method for detecting,
The control means blocks external light and causes the light irradiating means to irradiate the dust adhering target object and the image sensor substantially uniformly with light. Causing the image sensor to perform an imaging operation a plurality of times while performing a relative movement in a predetermined direction;
A detection unit comprising: a step of comparing a plurality of captured images obtained by the imaging operation and detecting an image of dust contained in the captured image.   The deriving means attaches to the dust adhesion target object using the image of the dust detected by the detection means and the distance in the optical axis direction from the light irradiation means to the dust adhesion target object and the image sensor. The dust detection method according to claim 7, further comprising a step of deriving an equal-magnification image of the existing dust. Dust adhering to a dust adhering object disposed on an optical path between an imaging optical system that forms an optical image of a subject and an imaging device in which an imaging surface is arranged on the imaging surface of the imaging optical system. A program for causing a dust detection device to perform a detection function,
The dust detection device;
With the outside light blocked and the light irradiating means irradiating the dust adhering object and the image sensor substantially uniformly with light, the driving means is directed to a predetermined direction of the dust adhering object with respect to the image sensor. Control means for causing the image sensor to perform an imaging operation a plurality of times while performing relative movement of
A program for comparing a plurality of captured images obtained by the imaging operation to function as detection means for detecting a dust image included in the captured image.   The program according to claim 9, wherein the dust detection device further includes an image of the dust detected by the detection means, and a distance in the optical axis direction from the light irradiation means to the dust adhesion target object and the image sensor. And a program for functioning as derivation means for deriving an equal-magnification image of the dust adhering to the dust adhesion object.

Images