JP2007226048A - Dust detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device capable of surely obtaining the position of dust that exists within a photographing machine, before taking images with the photographing machine. <P>SOLUTION: A convex lens is disposed such that the optical axis of the convex lens coincides with the central axis of one end of a hollow cylindrical body made of a material that does not transmit light. Also, a point light source is disposed at the other end of the cylindrical body and on the focal point of the projection lens disposed on the central axis of the cylindrical body. Light rays emitted from the point light source and extending parallelly from the convex lens are emitted to the photosensitive part of a camera. Accordingly, all dust, not only dust sticking to the photosensitive part but also dust floating ahead of the photosensitive part, is projected on the photosensitive part. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a dust detection device that detects a minute suspended matter attached to an image detection unit in a video device or drifting in the vicinity thereof.

  A photography method for forming an image such as a landscape on a dry plate coated with photosensitive fine particles has been practiced for a long time. In this photography method, there is fine dust on the space between the lens that captures the image and the dry plate that forms the image, or on the dry plate, and the shadow is photographed on the dry plate at the time of shooting and formed on this Reduce the quality of images. In order to avoid such inconvenience, the photographer blows air inside the camera in advance before taking a picture and performs an operation after removing the dust. Since there is no method for confirming whether or not all the dust inside the camera has been removed, the image of the dust remaining in the photographed image is often unexpectedly projected on the dry plate.

Recently, millions of CCD (Charge Coupled Device) photosensitive elements have been installed in the photosensitive part of the conventional photographic machine, and the captured image signals are transferred to a personal computer or the like provided outside the camera. So-called digital cameras have been developed. The shadow of dust existing between the lens and the photosensitive portion of the camera must reduce the quality of the captured image. In order to avoid the conventional inconvenience of this type of camera, in the type of camera with the lens that can be removed, air is blown into the camera before taking a picture, and the floating dust and photosensitive parts are taken as before. The adhering dust was removed. Also, there is a dust removal structure as shown in Patent Document 1 below, but it has an extremely complicated structure. However, with this dust removal method, there is no way to check for the presence of dust in the camera as in the conventional case. This causes a disadvantage that the shadow of dust remains in the image after shooting. For this reason, it is certain that a person who is taking a picture is taking a lot of time to remove the shadow of the dust thus photographed from the image data after photographing.
JP 2002-271661 A

  Therefore, the problem to be solved by the present invention is to obtain an apparatus capable of reliably grasping the position of dust existing in the camera before taking a picture with the camera.

In order to solve the above-mentioned problem, the invention according to claim 1 of the present application is to provide a window at one end of a hollow casing made of a light-impermeable material so that the window of the camera is desired. From the lens attached to the camera, the point tube is mounted at the position where the optical axis of the lens of the camera intersects the wall surface of the tube and near the focal point of the lens. Provided is a dust detection device that irradiates a parallel light beam extending in parallel to a photosensitive portion of a camera.
In the invention according to claim 2 of the present application, a window is provided at one end of a hollow casing made of a light-impermeable substance, a convex lens is attached to the window, and a wall at the other end of the casing is A dust source is configured by placing a point light source near the focal point of the convex lens, and this dust detector is placed in front of the camera with the lens removed, and the optical axis of the convex lens is aligned with the central axis of the camera and attached to the camera. A dust detector is provided that irradiates a photosensitive part of a camera with parallel rays emitted from the point light source and extending in parallel from a convex lens.
According to a third aspect of the present invention, in addition to the first or second aspect, the point light source is an external light leaking from a needle hole.
According to a fourth aspect of the present invention, in addition to the first aspect or the second aspect, the point light source is a self-luminous point light source.
The invention according to claim 5 of the present application is characterized in that in addition to the invention according to claim 1 or claim 2, a milky white translucent light scattering plate is attached to the point light source. Providing equipment.
According to a sixth aspect of the present invention, in addition to the first or second aspect, the point light source finely adjusts the distance from the convex lens on the central axis. A detection device is provided.
The invention according to claim 7 of the present application provides a dust detection device characterized in that, in addition to the invention according to claim 1 or 2, the inside of the casing is covered with a scattered light absorption layer.

  The present invention provides a window at one end of a hollow casing made of a light-impermeable material, attaches the casing to the camera so that the window is desired for the camera lens, and the optical axis of the camera lens. A point light source is arranged at a position that intersects the wall surface of the barrel and in the vicinity of the focal position of the lens, and a parallel light beam emitted from the point light source and extending in parallel from the lens attached to the camera is irradiated to the photosensitive portion of the camera A dust detection device or a hollow casing made of a light-impermeable material is provided with a window at one end and a convex lens is attached to the window, and the focal point of the convex lens is fixed to the wall at the other end of the casing. A point light source is arranged in the vicinity to constitute a dust detection device, this dust detection device is placed in front of the camera with the lens removed, and the optical axis of the convex lens is aligned with the center axis of the camera and attached to the camera. Since the dust detection device is configured to irradiate the photosensitive part of the camera with a parallel light beam emitted from the light source and extending in parallel from the convex lens, the light beam reaching the photosensitive part of the camera becomes parallel light. Needless to say, the dust adhering to the photosensitive portion is projected on the photosensitive portion up to the dust floating in front of the photosensitive portion. Therefore, if these are removed by known means, all the dust can be removed. Furthermore, if the image projected on the photosensitive part is enlarged and the contrast is increased, even fine dust can be detected, which is useful for removing it.

Next, the best mode for carrying out the present invention will be described.
The dust detection device according to the present invention can be applied to, for example, a lens interchangeable digital single-lens reflex camera, and is used by mounting the dust detection device on a lens mount like a normal lens.
The dust detection device has a cylindrical casing, and a lens of the camera is fitted into a window provided at one end of the casing on the central axis, or a convex lens is disposed. The length of the barrel is the same as the focal length of the camera lens or the focal length of the convex lens, and a pinhole is provided in the vicinity of the focal position at the other end of the barrel. A dark milky plate or milky white sphere is attached to the pinhole to diffuse light extending from the pinhole toward the convex lens. Note that light extending from the convex lens toward the photosensitive part of the digital single lens reflex camera becomes parallel light, so the distance from the convex lens to the photosensitive part is irrelevant, and there are many cameras to which this dust detection device can be applied.
For example, for use in a 35 mm full-size photosensitive part, the diameter of the convex lens attached to the dust detector must be at least φ43.3 mm.

Next, an example in which a convex lens is provided in the dust detection device according to the present invention will be described in detail with reference to the drawings.
FIG. 1 is a configuration diagram when the present invention is applied to an interchangeable lens digital single-lens reflex camera.
In FIG. 1, reference numeral 1 denotes a dust detection device according to the present invention. Reference numeral 2 denotes an interchangeable digital single-lens reflex camera, and the dust detection device 1 is fitted into a lens mount 3 of the interchangeable lens digital single-lens reflex camera 2. The interchangeable lens digital single-lens reflex camera 2 is provided with a photosensitive unit 4 in which millions of CCD elements are arranged in a two-dimensional rectangle. The photosensitive portion 4 is disposed at a focal position of a lens that is interchangeably attached to the lens mount 3. Behind the interchangeable lens digital single-lens reflex camera 2, a liquid crystal display unit 5 for displaying an image projected on the photosensitive unit 4 and a finder window 6 for viewing an image taken from the lens are provided.

The dust detection device 1 includes a rod cylinder 7 made of a light-impermeable synthetic resin or metal. A mounting portion 8 serving as a window to be fitted into the lens mount 3 of the lens interchangeable digital single-lens reflex camera 2 is attached to one end of the barrel 7. Usually, the mounting portion 8 is screwed into the dust mount 1 or the lens mount 3 or fitted in a bayonet manner. A convex lens 10 is fixed by a lens fixing portion 9 in the vicinity of the mounting portion 8 of the barrel 7. The diameter of the convex lens 10 is φ120 mm. The convex lens can be substituted with a lens attached to the camera.
A slightly larger hole 11 is formed on the central axis 14 of the casing 7 at the other end of the casing 7, and the hole 11 is closed by a pinhole plate 12. A needle hole 12 ′ is formed in the center of the pinhole plate 12, and the position thereof is on the central axis 14 of the barrel 7 and the centerline of the camera overlapping therewith. A milky white translucent light diffusing plate 13 or milky white sphere is attached to the pinhole plate 12 so as to close the needle hole 12 '. Note that the needle hole 12 'of the pinhole plate 12 is displayed considerably larger than the actual size for easy explanation and visual inspection. In FIG. 1, reference numeral 15 denotes an image controller housed in the camera 2. In the image controller 15, there is a frame memory 16 for storing a signal for one frame obtained by taking an image signal formed by the photosensitive unit 4 by a scanning operation. The signal for one frame stored here is read at a constant short interval and displayed on the liquid crystal display unit 5. The video signal output from the frame memory 16 is input to the image storage memory 17. Each time the shutter 18 is pressed, this signal is stored frame by frame. The video signal stored here can be taken out of the camera and taken into a personal computer connected to the camera to display an image or perform image processing.

Next, the operation of the above embodiment will be described.
Before checking the presence or absence of dust inside the interchangeable lens type digital single-lens reflex camera 2, the lens is removed from the camera, and the dust detection device 1 is attached here. Then, the shutter 18 is turned toward the dust detector 1 toward the sky in the daytime or an indoor fluorescent lamp. The light that enters the rod cylinder 7 through the needle hole 12 ′ from the outside is condensed by the convex lens 10 and becomes a clear parallel light beam and reaches the photosensitive portion 4. Therefore, the photosensitive unit 4 detects dust A floating in the air and dust B adhering to the photosensitive unit 4 by the photosensitive unit 4. These dusts can be detected from those floating in the air to those adhering to the photosensitive portion 4 as well as fine ones floating in the air. When dust is detected on the liquid crystal display unit 5, the dust detection device 1 is detached from the camera 2, the detected dust is removed using an air blower, etc., and the dust detection device is attached again to remove the remaining dust. This operation is repeated until all dust in the camera is removed.
Since the detected dust is reliably captured by the photosensitive unit 4, if the image on the liquid crystal display unit 5 is enlarged or the contrast is increased by image processing of a personal computer, these small dusts may not be overlooked. Absent.
Further, when the convex lens of the dust detection device is replaced with a lens attached to the camera, the same effect as described above is obtained.

FIG. 2 is a cross-sectional view showing the actual structure of the present invention. Note that the drawing numbers assigned to FIG. 2 are given different drawing numbers from the same components as those in FIG. 1 in order to clearly explain the invention.
The dust detection device according to the present invention has a synthetic resin or metal cylindrical rod 50 that does not transmit light. A screw is cut inside one end of the rod 50, and a lens positioning washer 51 is first screwed into this screw. Next, the convex lens 52 is fitted into the lens positioning washer 51, the lens fixing washer 53 is screwed into the screw, and the convex lens 52 is fixed to one end of the barrel 50. A mount washer 55 having a parallel light passage hole 54 serving as a window at the center is screwed on the outside of the lens fixing washer 53. A fixing portion 56 for attaching the dust detection device to the lens mount of the camera is attached to the mount washer 55.
A screw is also cut inside the other end of the casing 50, and a pinhole plate 57 serving as a wall surface is screwed into this screw. A light passage hole 58 is formed in the center of the pinhole plate 57. Of course, the center axis CL of the rod 50 passes through the center of the light passage hole 58. Note that this line and the central axis of the camera overlap.
Inside the pinhole plate 57, a needle hole plate 60 made of a thin metal plate having a needle hole 59 in the center is attached. Further, the center axis CL passes through the center of the needle hole 59. A milky translucent plate 61 is attached to the inside of the needle hole plate 60 so as to close the needle hole 59. In addition, light absorbing layers 62 and 63 made of an irregular reflection preventing cloth for avoiding irregular reflection of light or a black light absorbing paint for preventing reflection of light are attached to the inside of the casing 50.
In the present invention, the position of the needle hole 59 must be on the focal point of the convex lens 52. For this reason, when screwing the pinhole plate 57 into the barrel 50, a jig is inserted into the claw hole 64 provided on the surface of the pinhole plate 57 and rotated to adjust the position of the needle hole 59. After the adjustment of this position, the washer 65 is screwed into this screw, and the pinhole plate 57 is fixed to the correct position of the rod cylinder 57.

  As Example 2 of this invention, the self-light-emitting point light source which can be lighted with a battery like the bean ball is arrange | positioned at the needle hole part of the said Example 1 like. Also in this embodiment, a milky white translucent light scattering plate is attached to the rear part of the point light source.

The third embodiment of the present invention is an embodiment in which the convex lens in the above two embodiments is replaced with a lens attached to the camera. Actually, when the actual diameter of the camera lens is larger than that of the photosensitive portion (such as telephoto and bright F), the camera lens can be substituted for the convex lens of the dust detection device.
FIG. 3 is a configuration diagram of an embodiment in which the third embodiment of the present invention is applied to a lens interchangeable digital single-lens reflex camera.
In FIG. 3, reference numeral 70 denotes a lens interchangeable digital single-lens reflex camera, which is provided with a photosensitive portion 4, a liquid crystal display portion 5, and a viewfinder window 6 as in the camera of the first embodiment. In addition, for example, a standard lens 71 having a focal length of 35 mm is attached to the camera 70. A filter attachment ring 72 for attaching a filter to the lens 71 is attached in front of the lens 71. A dust detection device 73 according to the third embodiment of the present invention is attached in front of the filter attachment ring 72.
The dust detection device 73 has a main casing 74. A screw portion 75 having a window at the center is provided at one end root portion of the main rod cylinder 74, and this screw portion 75 is screwed into the filter attachment ring 72. In front of the main casing 74, a rotating casing 76 for attaching a pinhole plate described later is attached. A screw portion 77 is also provided at the root portion of the rotating rod cylinder 76, and this screw portion 77 is rotatably screwed into the inside of the tip end of the main rod cylinder 74. The rotary rod 76 is formed in a cup shape, and is a tip wall surface, and a slightly larger hole 78 is formed on the central axis CL, and the hole 78 is closed by a pinhole plate 79. A needle hole 79 ′ is formed at the center of the pinhole plate 79, and the position thereof is on a central axis line CL that overlaps the center line of the camera. A milky white translucent light diffusion plate 80 is attached to the pinhole plate 79 so as to close the needle hole 79 '. Note that the needle hole 79 ′ of the pinhole plate 79 is displayed considerably larger than the actual size for easy explanation and visual inspection. The main casing 74, the rotating casing 76, and the pinhole plate 79 are made of a light-impermeable synthetic resin in addition to metals such as aluminum, magnesium, and bronze.
In this embodiment, when the position of the needle hole 79 ′ is not located on the focal point of the standard lens 71 due to the difference in the length of the filter mounting ring 72, the rotating rod 76 is rotated, and the needle hole 79 ′ is The position can be adjusted on the central axis CL.
In this embodiment as well, the interior of the main casing 74 and the rotating casing 76 may be covered with a light absorbing layer as in the above embodiment.

  As mentioned above, although this invention was demonstrated by the above-mentioned embodiment, various deformation | transformation and application are possible within the range of the main point of this invention, and these deformation | transformation and application are not excluded from the scope of the present invention.

  The present invention can be used not only for a dust detection device in a camera but also for dust removal of a television camera in which a lens can be removed.

FIG. 1 is a configuration diagram of an embodiment in which the present invention is applied to a lens interchangeable digital single-lens reflex camera. FIG. 2 is a cross-sectional view showing the actual structure of the present invention. FIG. 3 is a sectional view showing a third embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Dust detection device 2 ... Lens interchangeable digital single-lens reflex camera 3 ... Lens mount 4 ... Photosensitive part 5 ... Liquid crystal display part 6. ·········································································································································································· 8・ Pin hole plate 12 ′ ・ ・ ・ ・ Needle hole 13 ・ ・ ・ Light diffusion plate 14 ・ ・ ・ Center axis 15 ・ ・ ・ Image controller 16 ・ ・ ・ ・ ・ Frame memory 17 ・ ・ ・Image storage memory 18 ... Shutter 50 ... Cylinder 51 ... Lens positioning washer 52 ... Convex lens 53 ... Lens fixed washer 54 ... · · Parallel light passage hole 55 · · · Mount washer 56 · · · fixed portion 57 · · · Pinhole plate 58 ... Light passage hole 59 ... Needle hole 60 ... Needle hole plate 61 ... Translucent 62 ... Light absorption layer 63 ... ··· Light absorption layer 64 ··· Washer 70 · · · Lens interchangeable digital single-lens reflex camera 71 · · · Lens 72 · · · Filter mounting ring 73 · · · Dust detection Device 74 ... Main cylinder 75 ... Screw part 76 ... Rotating cylinder 77 ... Screw part 78 ... Hole 79 ... Pin hole Plate 79 '... Needle hole

Claims (7)

  A window is provided at one end of a hollow tube made of a light-impermeable material, and the tube is attached to the camera so that the window is desired for the camera lens. The optical axis of the camera lens is A point light source is disposed at a position intersecting with the wall surface and in the vicinity of the focal position of the lens, and a parallel light beam emitted from the point light source and extending in parallel from the lens attached to the camera is irradiated onto the photosensitive portion of the camera. Dust detector.   A window is provided at one end of a hollow casing made of a light-impermeable material, and a convex lens is attached to the window, and a point light source is disposed on the wall of the other end of the casing and near the focal point of the convex lens. The dust detector is configured in front of the camera with the lens removed, and is attached to the camera with the optical axis of the convex lens aligned with the central axis of the camera, emitted from the point light source and parallel to the convex lens. A dust detection device for irradiating a photosensitive part of a camera with a parallel light beam extending in the direction.   The dust detection apparatus according to claim 1, wherein the point light source is external light leaking from a needle hole.   The dust detection device according to claim 1, wherein the point light source is a self-luminous point light source.   The dust detection apparatus according to claim 1, wherein a milky white translucent light scattering portion is attached to the point light source.   The dust detection apparatus according to claim 1, wherein the point light source finely adjusts a distance from the convex lens on a central axis.   The dust detection device according to claim 1 or 2, wherein the inside of the casing is covered with a scattered light absorption layer.

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