JP5429769B2 - Aperture device, lens having aperture device, and video camera - Google Patents

Description

  The present invention relates to a diaphragm device suitably used for a lens system of an optical apparatus such as a video camera. In particular, the present invention relates to a diaphragm device in which an optical filter is attached to two diaphragm blades for light amount adjustment each having a notch, a lens incorporating the diaphragm device, and a lens for a video camera.

In general, a lens for a video camera such as a conventional surveillance camera uses a diaphragm device having two diaphragm blades called a galvano type.
In such a diaphragm device, an ND filter is attached to at least one of the diaphragm blades. A two-blade type diaphragm device to which an ND filter is attached is described in Patent Document 1, for example. In the field of surveillance, since a subject is photographed day and night by a surveillance camera, a high-sensitivity surveillance camera is often used. High-sensitivity cameras often use lenses that have a minimum aperture value of F / 360 in order to cope with the difference in the amount of light of the subject between day and night.

  In recent video cameras, the sensitivity of the image sensor is high, so when shooting a high-luminance subject, it is necessary to reduce the aperture diameter. When the aperture diameter is made extremely small, there arises a problem that the resolving power is lowered due to the diffraction phenomenon caused by the aperture opening. In order to solve this problem, as described above, in the diaphragm device having two diaphragm blades, the light transmittance is reduced so as to cover the bottom of one of the two diaphragm blades. A structure for mounting the ND filter is used. However, if the light transmittance of the ND filter is set too low so as not to be affected by the diffraction phenomenon when the minimum aperture value is set, a part of the imaging screen becomes dark when the aperture is stopped. In order to prevent such a phenomenon from occurring, there has been proposed an ND filter configured such that the amount of transmitted light decreases from the edge of the diaphragm blade toward the edge of the notch.

  Therefore, many stop devices having a structure in which an ND filter for reducing the light transmittance is attached so as to cover the bottoms of the notches of the two stop blades have been proposed. If an ND filter is attached to the bottom of each notch portion of the two diaphragm blades, when the aperture opening is reduced to a small size by each notch portion of the two diaphragm blades, the aperture opening is formed by the two ND filters. Since it is covered, the amount of light can be sufficiently reduced by a relatively large aperture. Thereby, the influence of the diffraction phenomenon by the aperture opening can be suppressed.

  However, when ND filters having the same density are attached to the bottoms of the notches of the two diaphragm blades, the diaphragm is made small and immediately before the diaphragm aperture is covered by the two ND filters, In the region where the light formed by each notch of the blade can transmit, the region where the two ND filters overlap, the region where only one of the two ND filters exists, and the ND filter There occurs a state in which there is no clear area. In such a state, there is a problem that the resolution is lowered due to the influence of the diffraction phenomenon, that is, the contrast of the subject is lowered. In order to prevent this problem, an ND filter has been proposed in which the amount of transmitted light decreases toward the aperture blade aperture (see, for example, Patent Document 1).

  As another conventional diaphragm device, a diaphragm notch is provided at the tip of each of two diaphragm blades moving in directions opposite to each other on a plane orthogonal to the optical axis, and the diaphragm notch faces each other to form a diaphragm aperture An apparatus is a device in which a first ND filter consisting of n ND filter members is disposed at least partially in a first concave notch, and a second ND filter consisting of n ND filter members is arranged on the tip side of the second concave notch. A diaphragm device has been proposed in which a third ND filter composed of 2n ND filters is disposed behind the second concave notch (see, for example, Patent Document 2).

  As another conventional diaphragm device, two diaphragm blades (2, 4) having a concave notch are arranged so that the notches (28, 36) face each other in one plane orthogonal to the optical axis (O). In the diaphragm device that changes the aperture of the diaphragm by moving the two blades toward or away from each other in the plane toward the optical axis, they are attached to cover the bottom of the notch of each diaphragm blade. In addition, there are two optical filters (6, 8) for reducing the amount of transmitted light, and the shape of the aperture opening formed by the edge of each optical filter and the notch of each aperture blade passes through the optical axis. A diaphragm device that is asymmetric with respect to a straight line orthogonal to the moving direction of each diaphragm blade has been proposed (see, for example, Patent Document 3).

JP-A-8-43878 JP 2002-258346 A JP 2004-12749 A

  In the conventional diaphragm device proposed by the above-mentioned Patent Document 1, there is a problem that the ND filter shape becomes complicated and it becomes difficult to manufacture the ND filter.

  Furthermore, when there is a linear portion at the end of the filter as in Patent Documents 1 to 3 described above, the aperture opening is a rhombus composed of the linear portion 1000 as shown in FIG. 14, for example. As a result, as shown in FIG. 15, there is a problem that a diffraction phenomenon 1002 based on Huygens's principle occurs due to diffraction of the straight line portion 1000. That is, as shown in FIG. 15, at the small aperture value, four diffraction images 1002 extending in a direction orthogonal to the linear end portion are generated on the imaging plane in addition to the high-luminance subject captured image. . These four diffraction images 1002 appear as harmful high-intensity ghosts that intensively extend linearly in a certain radiation direction. As shown in the simulation diagram of FIG. 16, in this diffraction image, light is intensively diffracted in the same direction, and a straight, high-brightness and high-contrast ghost is generated around the high-brightness subject portion, thereby providing a clear image. Prevents the formation of.

  Further, in the embodiment shown in FIG. 4 of the cited document 2, harmful high-intensity ghosts that extend linearly in a certain radial direction in a concentrated manner are generated by the linear end portions, thereby preventing the formation of a clear image.

(Object of invention)
The present invention has been made in view of the above-described problems of the diaphragm device in which an optical filter is attached to two diaphragm blades for light quantity adjustment having a notch, and the shape of the optical filter is not complicated and can be manufactured. Diffraction that extends easily from the high-intensity subject captured image in a direction perpendicular to the linear end portion on the image plane when the aperture value is small, with little occurrence of linear ghosts due to diffraction phenomenon based on Huygens' principle. It is an object of the present invention to provide an aperture device that generates very little image, a lens for an optical instrument and a video camera incorporating the same.

The present invention relates to an aperture device for adjusting the amount of light passing through a subject passing through an imaging lens.
A first diaphragm blade having a first diaphragm opening for adjusting the amount of light passing through the light beam from the subject;
A first optical filter attached to a part of the first diaphragm opening of the first diaphragm blade;
A second diaphragm blade having a second diaphragm opening for adjusting the amount of light passing through the subject;
A second optical filter attached to a part of the second aperture opening of the second aperture blade;
A support member for supporting the first diaphragm blade and the second diaphragm blade so as to be linearly movable;
An actuator for linearly moving the first aperture blade in a first direction and linearly moving the second aperture blade in a second direction opposite to the first direction;
At least one of the optical axis side ends of the first optical filter and the second optical filter intersects the optical axis and is parallel to the moving direction of the first diaphragm blade and the second diaphragm blade, and the first optical filter And the intersection of the second optical filter with the end on the optical axis side is A, and both end points of the end on the optical axis side are B and C, AB and AC are convex or concave facing the optical axis side. The angle of inclination of the tangent of each point between AB or AC with respect to BC continuously changes in a certain direction, and the inclination angle changes discontinuously in A, and the first diaphragm blade and the second A diaphragm device characterized in that A is further away from the optical axis than B and C in the moving direction of the diaphragm blades.

Embodiments of the present invention are as follows.
The convex or concave curve facing the optical axis side is an arc, an elliptical arc, or a parabola. Arcs, elliptical arcs, or parabolas are used in many technical fields, and their fabrication techniques have been established, and there is an advantage that the present invention can be implemented reliably and efficiently.

  The convex or concave curve facing the optical axis side includes a convex-only curve, a concave-only curve, or both a convex curve and a concave curve, each of which is an effect of the present invention. At the same time, there is little decrease in resolving power due to the diffraction phenomenon due to the end face of the optical filter, and it is possible to obtain a small image in a linear high-intensity ghost.

  The first optical filter and the second optical filter are ND filters or color filters, and each of the first and second optical filters has an effect of the present invention. It is possible to obtain a few images with a high-intensity ghost.

  According to the diaphragm device of the present invention, the optical filter shape is not complicated and easy to manufacture, and the diffraction phenomenon based on the Huygens principle does not occur linearly in the same direction. An object photographed image and a diffraction image extending in a direction orthogonal to the linear end portion are not generated in a straight line, and an effect that a clear image can be formed can be obtained.

  Embodiments of the present invention will be described below with reference to the drawings. An embodiment of the present invention described below is a surveillance camera provided with a diaphragm device including a diaphragm blade that moves linearly. In the present invention, the video camera is a concept including a surveillance camera, a portable video shooting camera, a business video shooting camera, and the like.

(1) 1st Embodiment Below, 1st Embodiment of this invention is described.
(Structure of surveillance camera)
First, the structure of the surveillance camera having the aperture device according to the first embodiment of the present invention will be described. Referring to FIG. 1, a monitoring camera 100 according to the present invention includes a camera body 102 for recording an image of a light beam from a subject, and an imaging lens 104 for passing a light beam from the subject. The imaging lens 104 is detachably attached to the camera body 102 by a lens mount 104m. As a modification, the imaging lens 104 may be fixed to the camera body 102. The imaging lens 104 includes an imaging lens optical axis 104 x, a front group optical system 106, a rear group optical system 108, and a diaphragm device 200. The rear group optical system 108 constitutes a focus lens system configured to be movable along the imaging lens optical axis 104x. Such a focus lens system is configured such that the front group optical system 106 and / or the rear group optical system 108 are movable.

  The imaging lens 104 includes a lens barrel 262. The lens barrel 262 includes a first tube portion 262a, a second tube portion 262b, a lens frame 262c that supports the rear group optical system 108, an aperture device introducing portion 262d, and a focus operation ring 262f. It is configured such that the rear group optical system 108 can be moved by rotating the focus operation ring 262f. It can also be configured such that the front group optical system 106 and / or the rear group optical system 108 can be moved by rotating the focus operation ring 262f. As the support structure of the front group optical system 106 and the rear group optical system 108, for example, a known structure as described in Patent Document 1 can be used. The aperture device 200 is inserted into the aperture device introducing portion 262d perpendicular to the imaging lens optical axis 104x. The diaphragm device 200 is disposed in the lens barrel 262 so that the center axis of the diaphragm device 200 and the center axis of the lens barrel 262 coincide with each other.

  The camera body 102 has a solid-state image sensor 130 for converting an object image formed by the imaging lens 104 into an electric signal, and an electric signal related to the image of the object output from the solid-state image sensor 130. An electrical signal processing unit 132; an image recording signal generating unit 134 for outputting a signal for recording an electrical signal relating to an image of the subject processed by the electrical signal processing unit 132; and a switch 138 for operating the surveillance camera 100; An operation control unit 140 for controlling the operation of the monitoring camera 100 is provided. The solid-state image sensor 130 can be constituted by a CCD or the like. The electric signal processing unit 132, the image recording signal generation unit 134, and the operation control unit 140 can be configured by a MOS-IC, a PLA-IC, or the like.

  An image recording device 150 is provided separately from the camera body 102. The image recording device 150 is composed of, for example, a VTR recorder. The image recording device 150 is connected to the camera body 102 by a connection cord 152. The connection cord 152 can supply power to the camera body 102 from the image recording device 150 and can send a signal for controlling the operation of the monitoring camera 100 from the image recording device 150 to the operation control unit 140. Composed. The connection cord 152 is configured so that an electrical signal relating to the image of the subject output from the image recording signal generation unit 134 of the camera body 102 can be sent to the image recording device 150.

  The image recording device 150 receives an electrical signal related to the subject image sent from the camera body 102 and operates a recording processing unit 154 and a recording processing unit 154 for performing processing for recording the subject image. A recording medium 156 for recording an image of the subject is provided. The recording medium 156 may be a VTR tape, or may be composed of a RAM card, flexible disk, optical disk, magneto-optical disk, CD-R, CD-RW, DVD-RAM, DVD-RW, or the like. The image recording device 150 includes an image display unit 160 for displaying an image of a subject sent from the monitoring camera 100, a switch 162 for operating the image recording device 150, and a power source for connecting the image recording device 150 to a power source. A power cord 164. As a power source for operating the image recording apparatus 150, an external AC power supply can be used, an external battery can be used, or a battery arranged in the image recording apparatus 150 can be used. . The recording medium can also be provided in the camera body 102. If necessary, a power source such as a battery can be arranged in the camera body 102. If necessary, the camera body 102 may be provided with a camera display unit (not shown) for displaying an image of the subject. In a portable video shooting camera, a professional video shooting camera, or the like, a camera display unit and a camera operation unit are preferably provided in the camera body 102. In a portable video camera or the like, the camera body 102 is preferably provided with a power supply unit, a control circuit, and the like.

(Structure of the diaphragm device)
2 to 4, the diaphragm device 200 supports the first diaphragm blade or upper blade 210, the second diaphragm blade or lower blade 220, and the upper blade 210 and the lower blade 220 so as to be linearly movable. And a galvanometer 240 constituting an actuator for linearly moving the upper blade 210 and the lower blade 220. The upper blade 210 and the lower blade 220 may be arranged on the opposite side of the diaphragm unit substrate 230 from the side where the galvanometer 240 is arranged, or may be arranged on the same side as the side where the galvanometer 240 is arranged.

  The upper blade 210 is supported with respect to the aperture unit substrate 230 so as to be positioned at the lowest position in the state of the minimum aperture value and positioned at the uppermost position in the state of the open aperture value. On the other hand, the lower blade 220 is supported with respect to the aperture unit substrate 230 so as to be positioned at the uppermost position in the state of the minimum aperture value and positioned at the lowermost position in the state of the open aperture value. That is, as the aperture value is opened from the minimum aperture value toward the open aperture value, the upper blade 210 moves linearly upward, and the lower blade 220 moves linearly downward.

  The meter lever 242 is fixed to the output part 240a of the galvanometer 240. The meter lever 242 includes a central portion 242a, an upper blade operating arm 242b for operating the upper blade 210, an upper blade operating pin 242c for linearly moving the upper blade 210 in the first direction, and the lower blade 220. A lower blade operating arm 242d for operating and a lower blade operating pin 242e for linearly moving the lower blade 220 in a second direction different from the first direction. When the output part of the galvanometer 240 rotates by a certain angle, the upper blade 210 is linearly moved in the first direction by the upper blade operation pin 242c, and the lower blade 220 is moved by the lower blade operation pin 242e. It is comprised so that it can be linearly moved to the 2nd direction different from a direction. Here, when the first direction is an upward direction, the second direction is a downward direction, and when the first direction is a downward direction, the second direction is an upward direction. . That is, the first direction and the second direction are opposite directions.

  The meter lever 242 rotates in the clockwise direction when viewed from the side where the upper blade 210 and the lower blade 220 are disposed, thereby moving the upper blade 210 linearly upward, and simultaneously moving the lower blade 220 downward. It is configured such that it can be moved linearly and the diaphragm can be actuated towards the open value. The meter lever 242 rotates in a counterclockwise direction when viewed from the side where the upper blade 210 and the lower blade 220 are disposed, thereby moving the upper blade 210 linearly downward and at the same time moving the lower blade 220 upward. The diaphragm is moved in a straight line so that the diaphragm can be operated in the closing direction.

  The aperture unit substrate 230 includes an aperture unit opening 232 for allowing a light beam from a subject to pass through, a first blade guide pin 233a for guiding the lower blade 220 so as to be linearly movable, an upper blade 210, and a lower blade. The second blade guide pin 233b for guiding the 220 to move linearly, the third blade guide pin 233c for guiding the upper blade 210 and the lower blade 220 to move linearly, and the upper blade 210 And a fourth blade guide pin 233d for guiding so as to be linearly movable. The central axis 200x of the aperture unit opening 232 is configured to coincide with the imaging lens optical axis 104x when the aperture unit substrate 230 is attached to the imaging lens 104. The aperture unit opening 232 is preferably formed so as to include a circular portion centered on the central axis 200x.

  The upper blade 210 includes a first diaphragm opening, that is, an upper blade opening 212 for adjusting the amount of light passing through the subject, an upper blade interlocking hole 213 for receiving the upper blade operating pin, and the aperture unit substrate 230. A first upper blade guide hole 214b for receiving the second blade guide pin 233b and guiding the upper blade 210 so as to be linearly movable, and a third blade guide pin 233c are received so that the upper blade 210 can be linearly moved. And a second upper blade guide hole 214d for receiving the fourth blade guide pin 233d and guiding the upper blade 210 so as to be linearly movable. The upper blade opening 212 is positioned at the lower side and has an apex angle formed by two tangents of a lower part 212a formed in a circular shape and a circle that forms the lower part 212a and is located above the lower part 212a. And an upper portion 212b formed to be substantially perpendicular.

  An upper blade ND filter 216 constituting the first optical filter is provided so as to block the upper portion 212b. In other words, the first optical filter is preferably composed of an ND filter. In a video camera that records black and white video, the first optical filter is a neutral density filter such as a yellow (yellow: Y) filter, an orange (orange: O) filter, or a red (red: R) filter ( A colored filter for reducing the amount of light transmitted through the filter can also be used. The upper blade ND filter 216 is preferably ND1.2 having a transmitted light amount of about 6.3%.

As shown in FIG. 2, the diaphragm device 200 includes a first diaphragm blade 210 having a first diaphragm opening, that is, an upper blade opening 212 for adjusting the amount of light passing through a subject,
A first optical filter or upper blade ND filter 216 attached to a part of the first diaphragm opening or upper blade opening 212 of the first diaphragm blade 210;
A second diaphragm blade 220 having a second diaphragm opening, that is, a lower blade opening 222 for adjusting the amount of light passing through the subject,
A second optical filter or a lower blade ND filter 226 attached to a part of the second diaphragm opening 222 of the second diaphragm blade 220;
A support member for supporting the first diaphragm blade 210 and the second diaphragm blade 220 so as to be linearly movable, that is, a diaphragm unit substrate 230;
An actuator or galvanometer 240 for linearly moving the first diaphragm blade 210 in a first direction and linearly moving the second diaphragm blade 222 in a second direction opposite to the first direction; With
The optical axis end 216f of the first optical filter 216 and the optical axis end 226f of the second optical filter 226 intersect the optical axis 200x, and the first diaphragm blade 210 and the second diaphragm blade 220 move. A point of intersection between the line xx parallel to the direction and the end 216f on the optical axis side of the first optical filter 216 and the end 226f on the optical axis side of the second optical filter 226 is A, and both ends of the end on the optical axis side When the points are B and C, AB and AC are convex curves facing the optical axis side, and the inclination angle of each point tangent line between AB or AC with respect to BC continuously changes in a certain direction, The inclination angle changes discontinuously at A, and A is further away from the optical axis than B and C in the moving direction of the first diaphragm blade and the second diaphragm blade. AB or AC are all convex arcs facing the optical axis 200x, but may be elliptical arcs or parabolas.

  The upper blade interlocking hole 213 is formed in a long hole shape whose central axis extends in the horizontal direction. The first upper blade guide hole 214b, the second upper blade guide hole 214c, and the third upper blade guide hole 214d are each formed in a long hole shape whose central axis extends in the vertical direction. The upper blade interlocking hole 213 is disposed on the left side of the upper blade opening 212 as viewed from the direction in which the upper blade 210 is disposed.

  The lower blade 220 includes a second diaphragm opening, that is, a lower blade opening 222 for adjusting the amount of light passing through the subject, a lower blade interlocking hole 223 for receiving the lower blade operation of the galvanometer 240, and the first blade The first lower blade guide hole 224a for receiving the guide pin 233a and guiding the lower blade 220 so as to be linearly movable and the second blade guide pin 233b are received and guided so that the lower blade 220 can be linearly moved. And a third lower blade guide hole 224c for receiving the third blade guide pin 233c and guiding the lower blade 220 so as to be linearly movable. The lower blade opening 222 has an apex angle formed by two tangents of an upper part 222a that is located above and formed in a circular shape and a circle that is located below the upper part 222a and that constitutes the upper part 222a. And a lower portion 222b formed to be substantially perpendicular.

  A lower blade ND filter 226 constituting the second optical filter is provided so as to block the lower portion 222b. In other words, the second optical filter is preferably composed of an ND filter. In a video camera that records black and white video, the second optical filter is a neutral density filter such as a yellow (yellow: Y) filter, an orange (orange: O) filter, or a red (red: R) filter ( A colored filter for reducing the amount of light transmitted through the filter can also be used. The second optical filter is preferably composed of the same type of optical filter as the first optical filter.

  The configuration of the lower blade ND filter 226 is substantially the same as the configuration of the upper blade ND filter 216. The lower blade interlocking hole 223 is formed in a long hole shape whose central axis extends in the horizontal direction. The first lower blade guide hole 224a, the second lower blade guide hole 224b, and the third lower blade guide hole 224c are each formed in a long hole shape whose central axis extends in the vertical direction. The lower blade interlocking hole 223 is disposed on the right side of the lower blade opening 222 as viewed from the direction in which the lower blade 220 is disposed. That is, the position of the lower blade interlocking hole 223 is configured to be opposite to the position of the upper blade interlocking hole 213 with respect to the center of the lower blade opening 222 as viewed from the direction in which the lower blade 220 is disposed. Is done.

  In the assembled state of the aperture device 200, the center of the circular portion of the upper blade opening 212 when the aperture value is open is aligned with the center of the circular portion of the lower blade opening 222 when the aperture value is open. Composed. Further, in the assembled state of the diaphragm device 200, the center of the diaphragm unit opening 232 of the diaphragm unit substrate 230 coincides with the center of the circular portion of the upper blade opening 212 when the diaphragm value is open, and the diaphragm value. Is configured to coincide with the center of the circular portion of the lower blade opening 222 in the open state.

(Operation of the diaphragm device)
Next, with reference to FIG.2 and FIG.5, the effect | action of the diaphragm | throttle device 200 by 1st Embodiment of this invention is demonstrated. FIG. 2 shows the diaphragm device 200 in a state set to the open value. FIG. 5A shows the upper blade opening 212 and the end 216f of the upper blade ND filter 216 in a state set to a value slightly narrower than the open state, and the lower blade opening 222 and the end 226f of the lower blade ND filter 226. It shows. The non-filter part M indicates a region where neither the upper blade ND filter 216 nor the blade ND filter 226 exists.
FIG. 5B shows the upper blade opening 212 and the end 216f of the upper blade ND filter 216, the lower blade opening 222 and the lower blade in a state set to a value slightly reduced from the state shown in FIG. An end 226f of the ND filter 226 is shown.
FIG. 5C shows the upper blade opening 212 and the end 216f of the upper blade ND filter 216, and the lower blade opening 222 and the end 226f of the lower blade ND filter 226 in a state in which the value is further reduced. Show.
FIG. 5D shows the upper blade opening 212 and the end 216f of the upper blade ND filter 216, the lower blade opening 222 and the lower blade in a state where the value is further reduced from the state shown in FIG. An end 226f of the ND filter 226 is shown.
FIG. 5E shows the upper blade opening 212 and the end 216f of the upper blade ND filter 216, the lower blade opening 222, and the lower blade in a state where the value is further reduced from the state shown in FIG. An end 226f of the ND filter 226 is shown.
FIG. 5F illustrates the upper blade opening 212 and the end 216f of the upper blade ND filter 216, the lower blade opening 222, and the lower blade in a state in which the value is further reduced from the state illustrated in FIG. An end 226f of the ND filter 226 is shown.

The change of the aperture opening when the aperture value changes from the open state to the minimum aperture value is as follows. From the open state shown in FIG. 2, by operating the galvanometer 240, the upper blade 210 is moved downward and the lower blade 220 is moved upward. Then, the shape of the aperture opening 200p is changed from the state shown in FIG. 5A to the state shown in FIG. 5B, and further the aperture area of the aperture opening is reduced to the state shown in FIG. 5C. To do. In the state shown in FIG. 5C, the upper blade ND filter 216 and the lower blade ND filter 226 partially overlap each other at the aperture opening, and the non-filter portion M in which neither the upper blade ND filter 216 nor the blade ND filter 226 exists. Remains.
The opening area is further reduced from the state shown in FIG. 5C, and as shown in FIG. 5D, the upper blade ND filter 216 and the lower blade ND filter 226 partially overlap each other, and the upper blade ND The non-filter part M without the filter 216 and the blade ND filter 226 remains small. The opening area is further reduced from the state shown in FIG. 5D, and as shown in FIG. 5E, the upper blade ND filter 216 and the lower blade ND filter 226 are entirely overlapped, and the upper blade ND filter 216 is also a blade. There is no non-filter part M without the ND filter 226.

  As shown in FIG. 2, in the state in which the aperture device 200 is set to the open value, a substantially circular aperture opening is formed by the upper blade opening 212 of the upper blade 210 and the lower blade opening 222 of the lower blade 220. The Thus, when the aperture diameter of the aperture is large, the effective light beam passing through the aperture opening is large. Therefore, the upper blade ND filter 216 that covers the upper end of the aperture opening and the lower blade ND filter that covers the lower end of the aperture opening. The influence of flare generated from the end of 226 is small.

  When the diaphragm opening is narrowed from the state shown in FIG. 5B to the state shown in FIG. 5D through the state shown in FIG. 5C, the upper blade opening 212 of the upper blade 210 and The aperture opening formed by the lower blade opening 222 of the lower blade 220 is approximately diamond-shaped. In the state shown in FIG. 5D, a small non-filter portion M exists in the small rhomboid aperture, and the upper blade ND filter 216 and the lower blade ND filter 226 further cover most of the other, so the aperture The amount of transmitted light is further reduced. In the state shown in FIG. 5E, a region where only the upper blade ND filter 216 is present, a region where only the lower blade ND filter 226 is present, and a region where the upper blade ND filter 216 and the lower blade ND filter 226 overlap with each other. . In the state shown in FIG. 5 (f), only the region where the upper blade ND filter 216 and the lower blade ND filter 226 overlap each other. That is, the non-filter part M does not exist in the states of FIGS. 5 (e) and 5 (f).

(2) Second Embodiment Next, second to sixth embodiments of the diaphragm device of the present invention will be described. In the following description, only the points relating to the ends of the upper blade ND filter 316 and the lower blade ND filter 326 will be described, except that the second to sixth embodiments of the diaphragm device of the present invention are different from the first embodiment. About the structure which is common to 1 embodiment, the same reference number is attached | subjected and the description is abbreviate | omitted. Therefore, the description of the first embodiment of the diaphragm device of the present invention described above applies mutatis mutandis to the portions not described below.
In the second embodiment of the diaphragm device of the present invention, as shown in FIG. 6A, the inclination angle of the end 316f of the upper blade ND filter continuously changes in a constant direction even at A with respect to BC. That is, BC is one arc. In the end portion 326f of the lower blade ND filter 226, AB and AC are each convex facing the optical axis 200x. FIGS. 6A to 6F show a state in which the upper blade 210 and the lower blade 220 change so as to increase the overlap in the same manner as in FIGS. 5A to 5F. In the states of FIGS. 6D, 6E, and 6F, the non-filter portion M does not exist.

(3) Third Embodiment As shown in FIG. 7A, in the third embodiment of the aperture stop device of the present invention, the end 416f of the upper blade ND filter faces the optical axis 200x in AB and AC, respectively. It is a concave. In the end 426f of the lower blade ND filter 226, AB and AC are each convex facing the optical axis 200x. FIGS. 7A to 7F show a state in which the upper blade 210 and the lower blade 220 change so as to increase the overlap in the same manner as in FIGS. 5A to 5F. In the state shown in FIGS. 7E and 7F, the non-filter part M does not exist.

(4) Fourth Embodiment As shown in FIG. 8A, in the fourth embodiment of the diaphragm device of the present invention, the end 516f of the upper blade ND filter faces the optical axis 200x in AB and AC, respectively. It is convex. In the end 526f of the lower blade ND filter 226, AB is a convex facing the optical axis 200x, and AC is a concave facing the optical axis 200x. FIGS. 8A to 8F show a state in which the upper blade 210 and the lower blade 220 change so as to increase the overlap in the same manner as in FIGS. 5A to 5F. In the states of FIGS. 8E and 8F, the non-filter part M does not exist.

(5) Fifth Embodiment In the fifth embodiment of the aperture stop device of the present invention, as shown in FIG. 9A, the end 616f of the upper blade ND filter faces the optical axis 200x in AB and AC, respectively. It is a concave. In the end 626f of the lower blade ND filter 226, AB is a convex facing the optical axis 200x, and AC is a concave facing the optical axis 200x. FIGS. 9A to 9F show a state in which the upper blade 210 and the lower blade 220 change so as to increase the overlap in the same manner as in FIGS. 5A to 5F. In the state of FIGS. 9E and 9F, the non-filter part M does not exist.

(6) Sixth Embodiment In the sixth embodiment of the diaphragm device of the present invention, as shown in FIG. 10 (a), the upper blade ND filter is not attached to the upper blade 210. In the end 726f of the lower blade ND filter 226, AB is a convex facing the optical axis 200x, and AC is a convex facing the optical axis 200x. In FIGS. 10A to 10E, the non-filter portion M is sequentially reduced. In the state shown in FIG. 10 (f), the non-filter portion M does not exist, and all the aperture openings are covered with the lower blade ND filter 226.

(Effect of 1st Embodiment)
As shown in FIG. 11, the aperture opening has a diamond shape formed by the arc portion 2000. As a result, as shown in FIG. 12, the diffraction phenomenon based on Huygens's principle does not occur linearly in the same direction due to the diffraction of the straight line portion 2000, but is dispersed and generated in the radial direction. As a result, as shown in the simulation diagram of FIG. 13, light is diffracted intensively in the same direction, and a straight high-brightness ghost is not generated around the high-brightness subject portion, and a clear image is formed. The

  Although the invention has been described with reference to several preferred embodiments, these embodiments should not be construed as limiting the invention. Those skilled in the art will readily be able to conceive alternatives and modifications of the above embodiments, which fall within the scope of the invention as defined by the claims. In particular, the camera to which the aperture device of the embodiment of the present invention is applied may be a camera other than a video camera.

1 is a schematic cross-sectional explanatory diagram of a video camera according to a first embodiment of the present invention. It is a front view of the diaphragm | throttle device of 1st Embodiment of this invention. It is a front view which shows the upper blade | wing of 1st Embodiment of this invention. It is a front view which shows the lower blade | wing of 1st Embodiment of this invention. It is explanatory drawing which shows the change of the shape of the aperture opening in each aperture opening in the aperture_diaphragm | restriction apparatus by 1st Embodiment of this invention. It is explanatory drawing which shows the change of the shape of the aperture opening in each aperture opening in the aperture device by 2nd Embodiment of this invention. It is explanatory drawing which shows the change of the shape of the aperture opening in each aperture opening in the aperture device by 3rd Embodiment of this invention. It is explanatory drawing which shows the change of the shape of the aperture opening in each aperture opening in the aperture device by 4th Embodiment of this invention. It is explanatory drawing which shows the change of the shape of the aperture opening in each aperture opening in the aperture device by 5th Embodiment of this invention. It is explanatory drawing which shows the change of the shape of the aperture opening in each aperture opening in the aperture device by 6th Embodiment of this invention. It is explanatory drawing which shows the state of the light beam in the aperture opening of the aperture_diaphragm | restriction apparatus of 1st Embodiment of this invention. It is an image figure which shows the real image of the high-intensity light source by the diaphragm | throttle device of 1st Embodiment of this invention. It is a simulation image figure of Huygens diffraction in the image formation position of the iris diaphragm of a 1st embodiment of the present invention. It is explanatory drawing which shows the state of the light beam in the aperture opening of the aperture device of a prior art. It is an image figure which shows the real image of the high-intensity light source by the diaphragm | throttle device of a prior art. It is a simulation image figure of Huygens diffraction in the image formation position of the diaphragm | throttle device of a prior art.

Explanation of symbols

M Non-filter unit 100 Surveillance camera 102 Camera body 104 Imaging lens 106 Front group optical system 108 Rear group optical system 130 CCD element 150 Image recording device 156 Recording medium 200 Aperture device 210 Upper blade 216 Upper blade ND filter 216f Upper blade ND filter End 220 Lower blade 226 Lower blade ND filter 226f Lower blade ND filter end 230 Diaphragm unit substrate 240 Galvanometer

Claims (1)

In an aperture device for adjusting the amount of light passing through a subject passing through an imaging lens,
A first diaphragm blade having a first diaphragm opening for adjusting the amount of light passing through the light beam from the subject;
A first optical filter which is attached to a part of the first aperture of the first aperture blade and is an ND filter or a color filter;
A second diaphragm blade having a second diaphragm opening for adjusting the amount of light passing through the subject;
A second optical filter, which is an ND filter or a color filter, attached to a part of the second diaphragm opening of the second diaphragm blade;
A support member for supporting the first diaphragm blade and the second diaphragm blade so as to be linearly movable;
An actuator for linearly moving the first aperture blade in a first direction and linearly moving the second aperture blade in a second direction opposite to the first direction;
At least one of the optical axis side ends of the first optical filter and the second optical filter intersects the optical axis and is parallel to the moving direction of the first diaphragm blade and the second diaphragm blade, and the first optical filter And the intersection of the second optical filter with the end on the optical axis side is A, and both end points of the end on the optical axis side are B and C, AB and AC are convex curves facing the optical axis. Yes, the inclination angle of the tangent of each point between AB or AC with respect to BC connecting B and C changes continuously in a certain direction, and the inclination angle changes discontinuously in A A diaphragm device, wherein A is farther from the optical axis than B and C in the moving direction of the first diaphragm blade and the second diaphragm blade.