JP2010268102A - Imaging system dust detector of digital camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an imaging system dust detector of a digital camera, which detects dust reflected on an image sensor without operating a shutter. <P>SOLUTION: The imaging system dust detector of the digital camera includes: a shutter device for opening/closing a photographic optical path between a photographic lens and an imaging system; and an illuminating means for illuminating a surface of an optical element placed nearest to the photographic lens, among optical elements of the imaging system, wherein the illuminating means includes a light emitting element and a light distributing optical element which are disposed outside an photographic optical path between the shutter device and the surface of the optical element, and the light distributing optical element distributes illuminating light emitted from the light emitting element so that the illuminating light is regularly reflected by the surface of the optical element. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an imaging system dust detection device for a digital camera, and more specifically, imaging capable of detecting dust attached to an imaging system without opening a shutter that opens and closes a photographing optical path in front of the imaging system. The present invention relates to a system waste detection apparatus.

  In conventional interchangeable lens digital cameras, dust, dust and other dust (hereinafter referred to as “dust”) enter the camera body (mirror box) when the lens is replaced, and further behind the shutter curtain when the shutter is opened. There is a problem of adhering to the surface of the optical element disposed in front of the image sensor unit located in the position. The dust adhering to the surface of the foremost optical element is imprinted as a shadow in the subject image formed on the light receiving surface of the image sensor, degrading the image quality. Here, the imaging system includes an optical element unitized with the image sensor, such as a CCD or CMOS type image sensor, and an infrared cut filter and a low-pass filter disposed on the front subject side, and the surface of the foremost optical element is Usually, it becomes a low-pass filter surface.

  To remove dust adhering to the low-pass filter surface, mirror up, hold the shutter open to expose the optical element surface, remove dust by attaching to the stick stick inserted from the mount side, A technique is known in which dust is blown away with an air blower or the like. Further, the applicant has proposed a technique for illuminating the surface of the optical element by providing a light emitting element at the bottom of the mirror box in order to make it easier to see when dust attached to the surface of the low-pass filter is removed (Patent Document 1).

JP 2004-32189 A

  However, the conventional imaging system illumination device cannot illuminate the surface of the low-pass filter unless the mirror is raised and the shutter is opened. That is, when the mirror is down and the shutter is closed, it is impossible to detect whether dust is attached to the surface of the optical element of the imaging system.

The present invention has been made in view of the problems of the prior art, and can detect that dust is attached to the imaging system without opening a light shielding member that blocks a photographing optical path to the imaging system. An object of the present invention is to obtain an imaging system dust detection device for a digital camera.
A further object of the present invention is to provide a dust detection apparatus that can capture dust attached to an imaging system as a bright image.

  The present invention that solves the above-described problems includes an imaging system that includes an imaging device that captures a subject image formed by a photographic lens, a shutter device that opens and closes a photographic optical path between the photographic lens and the imaging system, and the imaging Illuminating means for illuminating the surface of the optical element located closest to the photographing lens among the optical elements of the system, and the illuminating means is disposed outside the photographing optical path between the shutter device and the optical element surface The light distribution optical element is characterized in that the light distribution optical element distributes the illumination light emitted from the light emission element so as to be regularly reflected on the surface of the optical element.

  The image pickup dust detection apparatus of the present invention is mounted on a digital camera, the digital camera has a display for displaying an image picked up by the image pickup device, and the digital camera further includes the display with the shutter device closed. The light emitting element is turned on and an image of the surface of the optical element captured by the imaging element is displayed on the display.

  An imaging system dust detection device according to the present invention is mounted on a camera body of an interchangeable lens digital camera in which a photographic lens can be attached and detached, and the camera body has a display for displaying an image captured by the imaging device, The light emitting element is turned on in a state where the shutter device is closed, and an image of the surface of the optical element captured by the imaging element is displayed on the display.

  It is practical that the imaging system includes a low-pass filter, and the surface of the low-pass filter is the surface of the front optical element.

The light distribution optical element is a cylindrical lens, and the cylindrical lens is arranged such that a line connecting the centers of curvature of the cylindrical surfaces is arranged in parallel with one edge of the front optical element surface, and the light emitting element is One cylindrical lens or a plurality of cylindrical lenses are provided at predetermined intervals along the axial line.
It is preferable that a pair of the cylindrical lens and the light emitting element is arranged in parallel with a pair of opposed edges on the surface of the front optical element.

The light distribution optical element is a toric lens, and the toric lens is arranged such that a line connecting one curvature center of a toric surface is parallel to the front optical element surface, and the light emitting element is one or a plurality of light emitting elements. Is provided.
It is preferable that a pair of the toric lens and the light emitting element are arranged at diagonal positions on the surface of the foremost optical element.

  According to the present invention, the state of the surface of the optical element illuminated by the illumination light distributed by the light distribution optical element by emitting the light emitting element without opening the shutter device can be imaged by the imaging system. became. Furthermore, the light distribution optical element of the present invention distributes the illumination light emitted from the light emitting element so as to be regularly reflected on the surface of the optical element (at a position where there is no dust). As a result, the dust adhering to the surface of the optical element is imaged brightly, so that the dust can be detected more clearly.

1 is a cross-sectional view showing a main part of a camera body vertically cut along an optical axis in an embodiment in which the present invention is applied to an interchangeable lens type digital single-lens reflex camera. It is a block diagram which shows the main circuit structures of the digital single-lens reflex camera. It is a front view which shows the structure of the low-pass filter surface of an imaging system (imaging unit) applied to the digital single-lens reflex camera, and an imaging system dust detection apparatus. FIG. 2 is an enlarged cross-sectional view of a low-pass filter and an imaging system dust detection device in the cross-sectional view of FIG. 1. In FIG. 4, it is a figure which expands and typically shows the structure of the low-pass filter surface at the time of dust detection, and an imaging system dust detection apparatus. It is a front view which shows 2nd Embodiment of an imaging type dust detection apparatus. It is a front view which shows 3rd Embodiment of an imaging type dust detection apparatus. It is a front view which shows 4th Embodiment of an imaging type dust detection apparatus.

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is an embodiment in which the present invention is applied to an imaging unit of an interchangeable-lens digital single-lens reflex camera, and is a cross-sectional view illustrating a main part by cutting a camera body 10 vertically. FIG. It is a block diagram which shows a main circuit structure.

  The camera body 10 has a main mirror 13 and a shutter unit 15 as main optical elements from the side of the mount unit 12 where the photographic lens is detachably mounted, and an imaging system in a back space opened and closed by the shutter unit 15. An imaging unit 50 having an image sensor 51 is disposed. A finder optical system including a focusing screen 17, a pentaprism 18, and an eyepiece lens 19 is disposed above the main mirror 13. Above the eyepiece lens 19, a photometric sensor 20 that receives a part of the subject light beam emitted from the pentaprism 18 is disposed. On the back surface of the main mirror 13, a sub mirror 14 is disposed that guides the subject light flux that has passed through the half mirror region of the main mirror 13 to the AF sensor unit 21 disposed below.

  On the back surface of the camera body 10, a display 45 that displays information related to the shooting function such as a shooting mode and a shot image is provided.

  Further, as shown in FIG. 2, a main CPU (control means) 31 that controls the camera body 10 and the photographing lens 100 in an integrated manner is mounted in the camera body 10, and the main CPU 31 includes AF control, Shooting control such as AE control, shutter unit 15 control, and image sensor 51 operation control, and various operation controls based on the operation of various operation switches are performed.

  The main CPU 31 is connected to the lens CPU 101 in the photographic lens 100 via a contact terminal provided on the mount unit 12, and various information communication such as lens-specific data, the state of the photographic lens 100, or the state on the camera body 10 side. I do.

  The main CPU 31 is connected with a photometric sensor 20 and an AF sensor unit 21 as sensors, a DSP (Digital Signal Processor) 33 as a control and image signal processing system, a photometric switch 35 as a switch, a release switch 36 and a mode switch 37. As a drive system, a motor driver 39, a shutter drive circuit 40, a motor driver 43, and the like are connected. The AF motor 38 is driven and controlled by the main CPU 31 via the motor driver 39, the mirror motor 41 and the charge motor 42 via the motor driver 43, and the shutter unit 15 via the shutter drive circuit 40, respectively.

  The image sensor 51 is driven and controlled by the DSP 33 under the control of the main CPU 31. The pixel signal photographed and output by the image sensor 51 is processed by the DSP 33. The DSP 33 generates image data from drive control of the image sensor 51 and pixel signals photographed and output by the image sensor 51, displays the image on the display 45, converts the image data into a predetermined format, and converts the image data into a memory card (recording medium). ) A processor that performs overall control of image signal processing, display processing, and image recording processing, such as processing for recording in 200.

  The shutter unit 15 is a so-called focal plane shutter, and is installed so that the front curtain and the rear curtain face the low-pass filter surface 54 a of the image sensor 51. The shutter unit 15 is driven to a charged state in preparation for photographing by a charge motor 42 driven via a motor driver 43. At the time of exposure, it is driven by the shutter drive circuit 40 under the control of the main CPU 31, opens and closes the photographing optical path according to the time difference between the start of the front curtain and the rear curtain, and passes the subject luminous flux from the photographing lens 100 while it is open. Thus, a subject image is formed on the light receiving surface 51 a of the image sensor 51. Further, when the above-described exposure operation is performed, the shutter unit 15 is driven to a charged state in preparation for photographing by a charge motor 42 driven via a motor driver 43.

  The main mirror 13 is pivotally supported by a rotating shaft 13 a provided near the upper end thereof, and is provided with a down (observation) position shown in FIG. 1 and an up (observation) position facing the focusing screen 17. Rotate between. The main mirror 13 is moved up and down by the driving force and spring force (not shown) of the mirror motor 41 driven via the motor driver 43. In the observation state shown in FIG. 1, most of the light beam (subject light) that has passed through the photographing lens 100 and entered the camera body 10 is reflected by the main mirror 13 and enters the focusing screen 17. Part of the subject light that has passed through the focusing screen 17 and exited from the pentaprism 18 enters the photometric sensor 20. The photometric sensor 20 outputs a photometric signal corresponding to the amount of received light to the main CPU 31. The main CPU 31 based on the input photometric signal, the shutter speed that is the charge accumulation time (exposure time) of the image sensor 51, and the aperture (aperture value) of an aperture (not shown) provided on the photographing lens 100 side. And driving control is performed with the calculated value at the time of photographing.

  The central region of the main mirror 13 is a half mirror, and a part of the light beam incident from the photographing lens 100 is transmitted through the main mirror 13 and reflected downward by the sub mirror 14 provided on the back side of the main mirror 13. And enters the AF sensor unit 21.

  The AF sensor unit 21 is a so-called pupil division phase difference type distance measuring sensor having a CCD sensor at a position optically equivalent to the light receiving surface 51a of the image sensor 51, and detecting a predetermined focus in a photographing screen (not shown). A pair of subject image signals that are in focus in the area are output to the main CPU 31 as AF video signals. The main CPU 31 calculates a defocus amount based on the AF video signal, and a lens driving direction for moving the focusing lens FL to the in-focus position based on the defocus amount and lens data unique to the photographing lens 100. Then, the driving amount is calculated, and the AF motor 38 is driven and controlled (AF driving control). The driving force of the AF motor 38 is transmitted to the gear unit 103 via a joint provided in the mount portion 12 of the camera body 10 and a joint provided in the mount portion on the photographing lens 100 side, and the focusing lens FL is moved to the optical axis. Driven in the direction.

  The camera body 10 is provided with a release button (not shown) linked to the photometry switch 35 and the release switch 36 and a mode button (not shown) linked to the mode switch 37. When the metering switch 35 is turned on by half-pressing the release button and the release button is fully pressed, the metering switch 35 is kept on and the release switch 36 is turned on. The mode switch 37 is turned on / off in response to the pressing operation of the operation mode setting button, and each time it is turned on, the photographing mode that can be photographed and the contamination of the low-pass filter surface 54a that is the optical element surface of the image sensor 51 are detected. The dust check mode is switched to either the dust check mode or the sensor cleaning mode that enables the low-pass filter surface 54a to be cleaned.

  The image pickup unit 50 includes a casing 52 having a rectangular shallow recess accommodating the image sensor 51, an infrared cut filter (infrared absorption filter) 53 installed so as to cover the opening of the recess of the casing 52, and an infrared cut filter And a low-pass filter 54 installed on the front side of 53. In this embodiment, the surface 54 a of the low-pass filter 54 is the optical element surface of the imaging unit 50. The infrared cut filter 53, the low-pass filter 54, and the low-pass filter surface 54a are provided in parallel with the light receiving surface 51a of the image sensor 51.

  In this imaging unit 50, the light receiving surface 51a of the image sensor 51 is perpendicular to the optical axis O of the photographing lens 100 mounted on the mount unit 12, and the center of the imaging region of the light receiving surface 51a is the optical axis O. Is attached to the camera body 10 so as to pass.

  An illumination device that illuminates the low-pass filter surface 54 a is mounted between the shutter unit 15 and the imaging unit 50. Here, an LED 71 as a light emitting element, and a cylindrical lens 73 as a light distribution optical element are disposed between the LED 71 and the low-pass filter surface 54a. The LED 71 is controlled to be turned on via the driver 72 under the control of the main CPU 31.

  The cylindrical lens 73 is disposed so that the axis of curvature of the cylindrical surface 73a is parallel to the longitudinal edge (long side) of the low-pass filter surface 54a and the cylindrical surface 73a faces the LED 71. The LED 71 is disposed so as to face the central position in the axial direction of the cylindrical lens 73. The cylindrical lens 73 has a condensing function in a direction orthogonal to the low-pass filter surface 54a, and has no condensing function in a parallel direction.

  The LED 71 and the cylindrical lens 73 are disposed in a space between the surface including the shutter curtain 15a and the low-pass filter surface 54a. That is, it is arranged at a position where the low-pass filter surface 54a can be illuminated even when the shutter unit 15 is closed.

  FIGS. 3 and 5 show how the LED 71 is lit in the dust check mode. In the dust check mode, without operating the shutter unit 15 and the main mirror 13, the LED 71 is turned on to drive the image sensor 51 to capture the low-pass filter surface 54 a and display the captured image on the display 45.

  Illumination light emitted from the LED 71 is converged by a light distribution action by the cylindrical lens 73 to converge a light beam that spreads in the normal direction (orthogonal direction) of the low-pass filter surface 54a. Since it is incident at a large incident angle that is slightly smaller than °, most of the incident illumination light is regularly reflected by the low-pass filter surface 54a. Accordingly, when there is no dust or the like on the low-pass filter surface 54a, the image on the low-pass filter surface 54a is displayed on the display 45 as a uniform black image.

  However, if the dust 80 is attached to the low-pass filter surface 54a, the illumination light incident on the dust 80 is reflected. The illumination light reflected in the direction of the low-pass filter surface 54a enters the low-pass filter 54 from the low-pass filter surface 54a, reaches the light receiving surface 51a, and is photoelectrically converted by the light receiving element 51b. That is, the dust 80 adhering to the low-pass filter surface 54 a is photographed as a bright image by the image sensor 51 and displayed on the display 45.

  As described above, the image of the low-pass filter surface 54 a captured by the image sensor 51 in the dust check mode is displayed on the display 45. The user can view the state of dust adhesion by looking at the display 45. The display on the display 45 is preferably displayed so as to coincide with the direction in which the image sensor 51 is viewed from the front surface (subject side) of the camera body 10 through the mount unit 12.

  In the above embodiment, the cylindrical lens 73 is arranged in a direction in which the cylindrical surface 73 a faces the LED 71. However, the cylindrical surface 73 a may be arranged in a direction facing the image sensor 51. Although one LED 71 is provided, two or more LEDs 71 may be arranged.

  A second embodiment of the present invention is shown in FIG. The second embodiment is characterized in that a pair of a cylindrical lens 74 and an LED 71 similar to the cylindrical lens 73 are disposed outside the opposing short side edge (short side) of the low-pass filter surface 54a (image sensor 51). Have Since the illumination light is irradiated from the opposite direction, the whole can be illuminated more uniformly, and when dust is present, it can be illuminated from a plurality of different directions, so that it is easier to detect.

  A third embodiment of the present invention is shown in FIG. This embodiment is characterized in that a toric lens 75 is used as a light distribution optical element. The toric lens 75 is equivalent to a configuration in which the cylindrical lens 73 has a light collecting power in a direction parallel to the low-pass filter surface 54a. That is, a line connecting one curvature center of the toric surface 75a of the toric lens 75 is positioned on an arc centered on the other curvature center, and this arc is formed in parallel with the low-pass filter surface 54a. Has been placed. According to the third embodiment, the illumination light that is emitted from the LED 71 and travels parallel to the low-pass filter surface 54a but spreads outside the low-pass filter surface 54a is focused by the toric lens 75. It becomes possible to illuminate 54a with more light fluxes.

  A fourth embodiment of the present invention is shown in FIG. The fourth embodiment is characterized in that two sets of LED 71 and toric lens 76 are prepared as a light emitting element and a light distribution optical element, and each set is disposed at a position outside one diagonal of the low-pass filter surface 54a. The toric lens 76 of this embodiment has such a light distribution characteristic that it can illuminate different half regions with priority on the diagonal line of the low-pass filter surface 54a.

  When a plurality of LEDs 71 are arranged as in the second and fourth embodiments described above, lighting control such as lighting / flashing each LED in turn and repeating all lighting, etc., is performed during sensor check. Good. The change in brightness makes it easier to detect dust attached to the low-pass filter surface 54a.

  In the embodiment of the present invention, the LED 71 is disposed between the shutter unit 15 and the imaging unit 50. Therefore, the low-pass filter surface 54a can be illuminated by the LED 71 without opening the shutter unit 15.

  Therefore, in the dust check mode of the single-lens reflex camera, the LED 71 is turned on with the shutter unit 15 closed, and the image sensor 51 is driven to take an image to display the image on the display 45. The light and dark state of the low-pass filter surface 54a is photographed by the photographing process in the dust check mode and displayed on the display 45, so that the state of dust adhesion can be understood. For example, when no dust is attached to the low-pass filter surface 54a, a dark uniform image with little noticeable change in brightness is displayed. When dust is attached, the portion is displayed as a bright image. Easy to understand the state of dust adhesion. Note that the display on the display 45 is preferably matched to the state in which the image sensor 51 is viewed from the photographing lens side.

  If, for example, dust 80 is confirmed from the display 45, the main mirror 13 is moved up by the sensor cleaning mode, and the shutter unit 15 is driven only in the front curtain and is fully opened. To remove the dust 80. At that time, the LED 71 is preferably turned on. As the LED 71 is turned on, the dust 80 looks bright and dark.

  Further, it is preferable to display on the display 45 an image captured in the dust check mode or an image captured by turning on the LED 71 before the mirror is raised. Even when it is difficult to see the dust with the naked eye, the position of the dust can be known by looking at the display 45.

  In the processing in the dust check mode, if dust adhesion cannot be confirmed, there is no need to clean. That is, since it is not necessary to fully open the shutter unit 15, there is no need to fully open the shutter unit 15, and adverse effects caused by exposing the image sensor 51 can be prevented. For example, there is no possibility that new dust will enter or damage the low-pass filter surface 54a.

The emission color of the LED 71 may be monochromatic light such as red or white. Moreover, when providing some LED, the thing of the same luminescent color may be used altogether, and the thing of the luminescent color which is different in all or one may be used.
Although an LED is used as the light emitting element, a laser diode may be used.

  In this embodiment, the low-pass filter 54 is disposed closer to the subject than the infrared cut filter 53, but there is an opposite arrangement. In this case, the surface of the optical element is the surface of an infrared cut filter.

DESCRIPTION OF SYMBOLS 10 Camera body 12 Mount part 13 Main mirror 14 Sub mirror 15 Shutter unit 21 AF sensor unit 31 Main CPU
33 DSP
35 Photometry switch 36 Release switch 37 Mode switch 41 Mirror motor 42 Charge motor 43 Motor driver 45 Display 50 Imaging unit 51 Image sensor 51a Light receiving surface 52 Casing 53 Infrared cut filter 54 Low pass filter 54a Low pass filter surface 71 LED (light emitting element)
73 Cylindrical lens (light distribution optical element)
74 Cylindrical lens (light distribution optical element)
75 Toric lens (light distribution optical element)
76 Toric lens (light distribution optical element)
100 Shooting Lens 101 Lens CPU

Claims (8)

An image pickup system including an image pickup device for picking up an image of a subject formed by the taking lens;
A shutter device that opens and closes a photographing optical path between the photographing lens and the imaging system;
Illuminating means for illuminating the surface of the optical element located closest to the photographing lens in the optical element of the imaging system,
The illuminating means includes a light emitting element and a light distribution optical element, which are disposed outside a photographing optical path between the shutter device and the optical element surface,
The light distribution optical element distributes the illumination light emitted from the light emitting element so that the illumination light is regularly reflected on the surface of the optical element.   The image pickup dust detection apparatus according to claim 1 is mounted on a digital camera, and the digital camera includes a display for displaying an image picked up by the image pickup device, and the digital camera further includes a shutter device closed. An image pickup dust detection apparatus that displays the image of the surface of the optical element picked up by the image pickup element in a state where the light emitting element is turned on.   The image pickup dust detection apparatus according to claim 1 is mounted on a camera body of an interchangeable lens digital camera in which a photographic lens can be attached and detached, and the camera body includes a display for displaying an image picked up by the image pickup device. An image pickup dust detection apparatus that turns on the light emitting element in a state where the shutter device is closed and displays an image of the surface of the optical element picked up by the image pickup element on the display.   The imaging system dust detection device according to any one of claims 1 to 3, wherein the imaging system includes a low-pass filter, and a surface of the low-pass filter is the surface of the front optical element.   5. The imaging system dust detection device according to claim 1, wherein the light distribution optical element is a cylindrical lens, and a line connecting a center of curvature of a cylindrical surface of the cylindrical lens is a surface of the front optical element. The image pickup dust detection apparatus is arranged in parallel with one edge of the cylindrical lens, and the light emitting element is provided at a central position in the axial direction of the cylindrical lens or at a predetermined interval along the axial line.   6. The imaging system dust detection device according to claim 5, wherein the cylindrical lens and the light emitting element are arranged in a pair in parallel with a pair of opposing edges on the surface of the foremost optical element.   5. The imaging system dust detection device according to claim 1, wherein the light distribution optical element is a toric lens, and the toric lens has a line connecting one curvature center of the toric surface with the forefront optical element. An image pickup dust detection apparatus, which is arranged in parallel with an element surface and has one or a plurality of light emitting elements.   8. The imaging system dust detection device according to claim 7, wherein a pair of the toric lens and the light emitting element are arranged at diagonal positions on the surface of the foremost optical element.

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