JP2015022061A - Focus detection unit and image capturing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mechanism which enables evaluation and assurance of focus detection accuracy by a focus detection unit alone and high-precision angle adjustment of the focus detection unit without increasing the size of an image capturing device.SOLUTION: A holding member 102 is attached to a fixed member 101 which is screw-fixed to a mirror box after adjusting a position and angle of the holding member 102. The angle adjustment of the holding member 102 with respect to the fixed member 101 is made by rotating pupil adjustment screws 1041, 1042 while the distance between the fixed member 101 and the holding member 102 is regulated by a stepped screw 1040. The pupil adjustment screw 1041, the stepped screw 1040, and a screw 103a are located on a substantially same straight line extending in a Y-direction, while a screw 103b, the pupil adjustment screw 1042, and a screw 103c are located on a substantially same straight line extending in the Y-direction at a distance in an X-direction from the pupil adjustment screw 1041, stepped screw 1040, and screw 103a.

Description

  The present invention relates to a focus detection unit mounted on an imaging apparatus such as a single-lens reflex camera, and an imaging apparatus including the focus detection unit.

  An imaging apparatus such as a digital single-lens reflex camera is equipped with a focus detection unit that detects the focus state of the imaging optical system. As the focus detection unit, for example, a field lens that divides light from the photographing optical system into two light beams, and a secondary image forming a pair of optical images (subject images) by re-imaging each of the two light beams. Some include a focus detection optical system including a lens. The focus detection unit converts a pair of subject images into electrical signals (image signals) by a light receiving element, and detects a focus state of the photographing optical system based on a phase difference between the pair of image signals.

  Incidentally, the focus detection unit is generally disposed at the lower part of the camera body, and reflects part of the subject light by the sub mirror provided in the photographing optical path so as to enter the focus detection unit. In this configuration, an adjustment mechanism for adjusting the angle between the optical axis of the subject light incident on the focus detection unit and the optical axis of the light receiving element, that is, the focus detection unit is attached to the camera body by adjusting the angle by a so-called pupil adjustment mechanism There is.

  For example, a mechanism has been proposed in which a focus detection unit is attached to a boss provided on a mirror box of a camera body with a screw via a coil spring (Patent Document 1). In this proposal, the mounting angle of the focus detection unit is adjusted according to the tightening amount of the screw, and the mounting portion is biased by the coil spring so that no posture change other than the adjustment angle occurs. The man-hour required for adjusting the incident angle of the incident light can be reduced.

JP 2000-19382 A

  However, in the above-mentioned Patent Document 1, since the adjustment of the mounting angle of the focus detection unit is performed between the mirror box and the focus detection unit, the focus detection accuracy of the focus detection unit is evaluated and guaranteed by the focus detection unit alone. I can't. In general, the focus detection accuracy is preferably guaranteed only by the assembly accuracy of the focus detection unit alone.

  In view of this, a mechanism for providing a fixing member for fixing to the mirror box in the focus detection unit and adjusting the angle between the fixing member and the holding member for holding the focus detection optical system can be considered.

  However, in such a mechanism, the fixing member needs a plurality of screw mounting portions for mounting on the mirror box and a plurality of screw mounting portions for angle adjustment. And, in order to avoid the interference of each mounting part, if the screw mounting part for mounting to the mirror box is arranged outside the screw mounting part for angle adjustment, the focus detection unit becomes large and the entire imaging device becomes large The problem that becomes.

  Thus, the present invention can evaluate and guarantee the focus detection accuracy of the focus detection unit alone, and can adjust the angle of the focus detection unit with high accuracy without increasing the size of the imaging device. The purpose is to provide a mechanism.

  In order to achieve the above object, a focus detection unit of the present invention holds an image sensor for focus detection and a focus detection optical system that guides incident subject light to the image sensor, and includes incident light of the subject light. A holding member having a first position restricting surface, a second position restricting surface, and a third position restricting surface which are planes substantially orthogonal to the axis, and the first attachment surface to which the holding member is attached, A fixing member that has the second mounting surface and the third mounting surface and is fixed to the apparatus main body of the imaging apparatus; and a first fastening member for fixing the fixing member to the apparatus main body; A second fastening member, a third fastening member, a regulating member that regulates an interval in the direction of the incident optical axis between the first mounting surface and the first position regulating surface, and the regulating member In a state where the interval is regulated, the second mounting surface and the second position A first adjusting member that adjusts a distance in the direction of the incident optical axis with respect to the restriction surface; and the third attachment surface and the third position restriction surface in a state where the distance is restricted by the restriction member. And a second adjustment member that adjusts the interval in the direction of the incident optical axis, wherein the long side direction of the shooting screen is the first direction and the short side direction of the shooting screen is the second direction. The second position restricting surface is spaced apart from the first position restricting surface in the second direction, and the third position restricting surface is located on the first position restricting surface. The first adjustment member, the regulating member, and the first fastening member are arranged in substantially the same straight line along the second direction, and are arranged apart from each other in the first direction. The second fastening member, the second adjustment member, and the third fastening member are the first adjustment member, the regulation member, and the like. Member, and characterized in that it is disposed substantially on the same straight line along the second direction at a position spaced in the first direction relative to the first fastening member.

  According to the present invention, the focus detection accuracy of the focus detection unit can be evaluated and guaranteed by the focus detection unit alone, and the angle adjustment of the focus detection unit can be performed with high accuracy without increasing the size of the imaging device. Become.

1 is a schematic cross-sectional view of a digital single-lens reflex camera that is an example of an embodiment of an imaging apparatus of the present invention. It is a perspective view which shows a mirror box and a focus detection unit. It is a disassembled perspective view of a focus detection unit. It is the disassembled perspective view which looked at the focus detection unit shown in FIG. 3 from the left side. It is the disassembled perspective view which looked at the focus detection unit shown in FIG. 3 from the lower side. (A) is sectional drawing in alignment with the center axis | shaft of the stepped screw and pupil adjustment screw in a focus detection unit, (b) is sectional drawing for demonstrating a stepped screw. It is the figure which looked at the focus detection unit from the side. It is the figure which looked at the focus detection unit from the bottom side.

  Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view of a digital single-lens reflex camera as an example of an embodiment of an imaging apparatus of the present invention.

  As shown in FIG. 1, in the digital single-lens reflex camera of this embodiment, a lens barrel 30 is detachably attached to a camera body 20. The camera body 20 is provided with a mirror unit 40, an optical filter 13, an image sensor 14, a finder optical system 50, a focus detection unit 100, a camera CPU 21, and the like. Here, the camera body 20 corresponds to an example of the apparatus body of the present invention.

  The mirror unit 40 is supported to be rotatable with respect to the mirror box 200. The mirror unit 40 includes a main mirror 2 composed of a half mirror and a sub mirror 3 that is rotatably supported with respect to the main mirror 2, and enters the imaging optical path (mirror down) when observing the viewfinder. Evacuate (mirror up) from the optical path.

  The viewfinder optical system 50 includes a focusing plate 10, a penta roof prism 11 for forming an erect image, an eyepiece lens 12, and the like. The image sensor 14 is composed of a CCD sensor, a CMOS sensor, or the like, photoelectrically converts a subject image formed through the photographing optical system of the lens barrel 30, and outputs an electrical signal. The camera CPU 21 is a controller that controls various calculations and various operations in the camera.

  The lens barrel 30 is an interchangeable lens unit that is detachably attached to a lens mount (not shown) provided in the mirror box 200, and includes the photographing lens 1, a memory 22, a focus motor 23, and the like. The memory 22 stores various information regarding the lens barrel 30. The photographing lens 1 constitutes a photographing optical system together with a focus lens (not shown) and the like. The focus motor 23 adjusts the focus of the photographing optical system by moving the focus lens in the optical axis direction. Focusing operation of the focus motor 23 is controlled by the camera CPU 21.

  Next, focus detection of the photographing optical system using the focus detection unit 100 will be described. First, light from the subject passes through the photographing optical system and then enters the main mirror 2 formed of a half mirror. Part of the light incident on the main mirror 2 passes through the main mirror 2, is reflected by the sub-mirror 3, and enters the field lens 4 of the focus detection unit 100.

  Since the field lens 4 is disposed on the primary (planned) imaging plane of the photographing optical system or an area in the vicinity thereof, a subject image is formed on the field lens 4 or in the vicinity thereof.

  The field lens 4 condenses incident light (light flux). The light beam that has passed through the field lens 4 passes through an optical filter 6 such as an infrared cut filter, and its pass range is limited by the diaphragm 7 and enters the secondary imaging lens 8. The light beam that has passed through two regions (pupil division regions) in the exit pupil of the field lens 4 is incident on the secondary imaging lens 8 by the function of dividing and limiting the light passage range by the diaphragm. Here, the field lens 4 and the secondary imaging lens 8 correspond to an example of a focus detection optical system of the present invention.

  The secondary imaging lens 8 re-images the two incident light beams on the light receiving sensor 9 that is an image sensor for focus detection. As a result, a subject image, which is a pair of optical images, is formed on the light receiving sensor 9 by the light flux from the two pupil division regions. The light receiving sensor 9 photoelectrically converts a pair of subject images and outputs a pair of image signals (electrical signals).

  The camera CPU 21 performs a correlation operation on the pair of image signals output from the light receiving sensor 9 to calculate a phase difference indicating a relative positional shift therebetween, and based on the phase difference, the camera optical system The focus state (defocus amount) is calculated. Then, the camera CPU 21 calculates a moving amount (driving amount) of the focus lens for obtaining a focused state based on the calculated defocus amount, and drives the focus motor 23 according to the calculation result to focus lens. Move. Thereby, focus adjustment is performed to obtain a focused state.

  On the other hand, the light reflected by the main mirror 2 forms an image on the focus plate 10 disposed at a position optically conjugate with the image sensor 14, and is diffused by the focus plate 10 and transmitted therethrough (subject image). ) Is converted into an erect image by the penta roof prism 11. The erect image is magnified by the eyepiece 12 and observed by the user.

  After the focus detection and focus adjustment described above are performed, the camera CPU 21 retracts the main mirror 2 and the sub mirror 3 out of the photographing optical path. As a result, the subject light that has passed through the photographing optical system forms an image on the image sensor 14 via the optical filter 13 including the infrared cut filter, and the image sensor 14 photoelectrically converts the image of the formed subject image to generate an electrical signal. Output. The camera CPU 21 generates an image based on the electrical signal output from the image sensor 14 and records the generated image on a recording medium or displays it on a display device.

  FIG. 2 is a perspective view showing the mirror box 200 and the focus detection unit 100. As shown in FIG. 2, the focus detection unit 100 is fixed to the lower part of the mirror box 200 with three screws 103a to 103c. In addition to the focus detection unit 100, the mirror box 200 supports various components of the camera such as the finder optical system 50 and the image sensor unit including the image sensor 14.

  Further, when the focus detection unit 100 is fixed to the mirror box 200, there is a possibility that a minute float occurs and the focus detection optical system is tilted. Therefore, the screws 103a and 103b are arranged along the X direction, which is the long side direction of the photographing screen described later, to prevent the floating in the X direction. Further, the screws 103b and 103c are arranged along the Y direction, which is the short side direction of the photographing screen described later, to prevent the floating in the Y direction. As a result, it is possible to prevent the float of the focus detection unit 100 from the mirror box 200 and to detect the focus with higher accuracy.

  Next, referring to FIG. 3 to FIG. 8, the focus detection unit 100 is attached with the angle adjusted with respect to the mirror box 200, and the incident light axis of the subject light to the focus detection unit 100 and the light of the light receiving sensor 9 An adjustment mechanism for aligning the axes will be described.

  FIG. 3 is an exploded perspective view of the focus detection unit 100. 4 is an exploded perspective view of the focus detection unit 100 shown in FIG. 3 as viewed from the left side. FIG. 5 is an exploded perspective view of the focus detection unit 100 shown in FIG. 3 as viewed from below.

  3 and 4, the X direction is the long side direction of the shooting screen, and the Y direction is orthogonal to the X direction and orthogonal to the incident optical axis of the subject light reflected and guided by the submirror 3. Direction, that is, the short side direction of the shooting screen. Here, the X direction corresponds to an example of the first direction of the present invention, and the Y direction corresponds to an example of the second direction of the present invention.

  As shown in FIGS. 3 to 5, the focus detection unit 100 includes a fixing member 101 and a holding member 102. The holding member 102 holds each member including the field lens 4 and the secondary imaging lens 8 constituting the focus detection optical system. A holding member 102 is attached to the fixing member 101, and the fixing member 101 is fixed to the mirror box 200 with three screws 103a to 103c in a state where the position and angle of the holding member 102 with respect to the fixing member 101 are adjusted. Here, the screw 103a corresponds to an example of the first fastening member of the present invention, the screw 103b corresponds to an example of the second fastening member of the present invention, and the screw 103c corresponds to the third fastening member of the present invention. It corresponds to an example of a member.

  As shown in FIGS. 3 and 4, protrusions 102 a to 102 c for adjusting the position and angle with respect to the fixing member 101 are provided on both sides in the X direction of the lower side portion of the holding member 102. The protrusions 102a and 102b are disposed on one side in the X direction, and the protrusion 102c is disposed on the other side in the X direction. The protrusions 102a and 102b are spaced apart from each other in the Y direction.

  The rear surface of the projection 102a, that is, the surface opposite to the fixing member 101 is provided with a position regulating surface 1080 that contacts the head of the stepped screw 1040. The rear surface of the projection 102b has a pupil adjustment screw 1041. The position regulating surface 1081 with which the head of the head contacts is provided. Further, a position regulating surface 1082 with which the head of the pupil adjusting screw 1042 comes into contact is provided on the back surface of the protrusion 102c. The position regulating surfaces 1081 to 1082 are all flat surfaces that are substantially orthogonal to the incident optical axis.

  Here, the position restricting surface 1080 corresponds to an example of the first position restricting surface of the present invention, and the position restricting surface 1081 corresponds to an example of the second position restricting surface of the present invention. Further, the position restriction surface 1082 corresponds to an example of a third position restriction surface of the present invention. The surfaces of the protrusions 102 a to 102 c, that is, the surfaces on the fixing member 101 side are biased surfaces 1060 to 1062 with which the compression coil springs 105 come into contact, respectively.

  As shown in FIG. 5, the fixing member 101 is provided with mounting surfaces 1070 to 1072 that face the biased surfaces 1060 to 1062 of the holding member 102. Then, the stepped screw 1040 is screwed to the mounting surface 1070 and regulates the interval in the incident optical axis direction between the position regulating surface 1080 and the mounting surface 1070. The pupil adjustment screws 1041 and 1042 are screwed into the attachment surfaces 1071 and 1072, respectively, and adjust the distance in the incident optical axis direction between the position regulating surfaces 1081 and 1082 and the attachment surfaces 1071 and 1072 by rotation.

  Here, the stepped screw 1040 corresponds to an example of the regulating member of the present invention, the pupil adjustment screw 1041 corresponds to an example of the first adjustment member of the present invention, and the pupil adjustment screw 1042 corresponds to the present invention. This corresponds to an example of the second adjustment member. The mounting surface 1070 corresponds to an example of the first mounting surface of the present invention, the mounting surface 1071 corresponds to an example of the second mounting surface of the present invention, and the mounting surface 1072 corresponds to the third mounting surface of the present invention. It corresponds to an example of the mounting surface.

  The light receiving sensor 9 is provided in the package 110, and as described above, the light receiving sensor 9 photoelectrically converts a pair of subject images and outputs a pair of image signals (electrical signals). The compression coil spring 105 is inserted into the stepped screw 1040 and the pupil adjustment screws 1041 and 1042 between the biased surfaces 1060 to 1062 of the holding member 102 and the mounting surfaces 1070 to 1072 of the fixing member 101, respectively. It is arranged with. The compression coil spring 105 generates a biasing force in a direction in which the interval between the biased surfaces 1060 to 1062 and the mounting surfaces 1070 to 1072 is increased.

  FIG. 6A is a cross-sectional view taken along the center axis of the stepped screw 1040 and the pupil adjustment screw 1041 in the focus detection unit 100. As shown in FIG. 6A, a screw insertion hole 1090 into which a stepped screw 1040 is inserted is formed between the biased surface 1060 and the position regulating surface 1080. Further, screw insertion holes 1091 and 1092 through which the pupil adjustment screws 1041 and 1042 are inserted are formed between the biased surfaces 1061 and 1062 and the position regulating surfaces 1081 and 1082, respectively.

  FIG. 6B is a cross-sectional view for explaining the stepped screw 1040. As shown in FIG. 6B, in the stepped screw 1040, the diameter of the shaft portion 1040c penetrating the screw insertion hole 1090 is larger than the diameter of the screw portion 1040a, and there is a gap between the screw portion 1040a and the shaft portion 1040c. A step surface 1040b is formed. The stepped surface 1040b abuts against the mounting surface 1070 of the fixing member 101, whereby the stepped screw 1040 cannot be tightened beyond a certain level.

  Accordingly, the position of the holding member 102 in the incident optical axis direction with respect to the fixing member 101 is regulated at the abutting position of the stepped screw 1040, and the focus detection optical system can be positioned at an appropriate position. For this reason, it is possible to improve the position adjustment accuracy of the focus detection optical system and shorten the adjustment time. Instead of the stepped screw 1040, a screw provided with an E-ring or the like at the position of the stepped surface 1040b may be used.

  Further, since the compression coil spring 105 is interposed, the distance between the position restricting surface 1081 and the mounting surface 1071 and the distance between the position restricting surface 1082 and the attaching surface 1072 are determined by tightening the pupil adjusting screws 1041 and 1042, respectively. It is possible to regulate and uniquely regulate by inclusion. Accordingly, by tightening or loosening the pupil adjustment screws 1041 and 1042, the attachment angle of the holding member 102 with respect to the fixing member 101 can be adjusted using the position regulated by the stepped screw 1040 as a reference. Then, after adjusting the attachment angle of the holding member 102, the fixing member 101 is attached to the mirror box 200 with screws 103a to 103c.

  FIG. 7 is a view of the focus detection unit 100 as viewed from the side. As shown in FIG. 7, the position regulating surface 1080 and the position regulating surface 1081 of the holding member 102 are not the same plane but are arranged at different positions having a step B in the incident optical axis direction. By disposing the position restricting surface 1080 and the position restricting surface 1081 with a step B, when the pupil adjusting screw 1041 is tightened or loosened in the optical axis direction for adjusting the angle of the holding member 102, the holding member 102. The rotation angle can be reduced. This makes it possible to reduce the adjustment sensitivity without increasing the dimension of the focus detection unit 100 in the Y direction.

  FIG. 8 is a view of the focus detection unit 100 as seen from the bottom side. In FIG. 8, a line E connecting the stepped screw 1040 and the pupil adjustment screw 1042 is arranged so as to be substantially parallel to the X direction which is the long side direction of the photographing screen. A line D connecting the stepped screw 1040 and the pupil adjustment screw 1041 is arranged to be substantially parallel to the Y direction, which is the short side direction of the captured image.

  As a result, by tightening the pupil adjustment screw 1041, the holding member 102 is rotated about the rotation axis that is substantially parallel to the X direction through the intersection of the center axis of the position regulating surface 1080 and the stepped screw 1040, and the angle is adjusted. The

  In addition, by tightening the pupil adjustment screw 1042, the holding member 102 passes through the intersection of the center axis of the position regulating surface 1080 and the stepped screw 1040 and rotates about a rotation axis substantially parallel to the Y direction to be angle-adjusted. . Since these rotation axes are orthogonal to each other, the pupil adjustment by the pupil adjustment screw 1041 and the pupil adjustment by the pupil adjustment screw 1042 can be adjusted independently for each direction. As a result, the adjustment time can be shortened.

  Further, in the present embodiment, as shown in FIG. 8, the pupil adjusting screw 1041, the stepped screw 1040, and the screw 103a are arranged in substantially the same straight line along the Y direction. The screws 103b, the pupil adjustment screws 1042, and the screws 103c are also substantially collinear along the Y direction at positions separated from the pupil adjustment screws 1041, the stepped screws 1040, and the screws 103a in the X direction. Is arranged. Thereby, the focus detection unit 100 can be configured more compactly.

  Specifically, the pupil adjustment screw 1041, the stepped screw 1040, and the screw 103a are not substantially collinear, for example, as compared to the case where the screw 103a is disposed outside the pupil adjustment screw 1041 and the stepped screw 1040. The focus detection unit 100 can be reduced in size in the X direction. Further, the focus detection unit 100 can be made smaller in the Y direction as compared with the case where the pupil adjustment screw 1041, the stepped screw 1040, the screw 103a, and the screw 103c are arranged in substantially the same straight line.

  Returning to FIG. 2, in this embodiment, the holding member 102 is provided with a notch 102d for fastening the screw 103c. The notch 102d is formed by reducing the thickness of the holding member 102 so that the screw 103c does not interfere with the holding member 102 when the screw 103c is fastened. As a result, the screw 103c can be arranged on the inner side, and when the screw 103b, the pupil adjusting screw 1042 and the screw 103c are arranged in substantially the same straight line along the Y direction, the focus detection unit 100 can be arranged more. It can be made small. As a result, the digital camera can be reduced in size.

  As described above, in the present embodiment, the focus detection accuracy of the focus detection unit 100 can be evaluated and ensured by the focus detection unit 100 alone, and high-precision focus detection can be performed without increasing the size of the digital camera. The angle of the unit 100 can be adjusted.

  The configuration of the present invention is not limited to that exemplified in the above embodiment, and the material, shape, dimensions, form, number, arrangement location, and the like can be changed as appropriate without departing from the scope of the present invention. It is.

  For example, in the above embodiment, the pupil adjusting screw 1041, the stepped screw 1040, and the screw 103a are arranged in substantially the same straight line in the Y direction, and the screw 103b, the pupil adjusting screw 1042, and the screw 103c are arranged in the Y direction. However, the present invention is not limited to this.

  For example, the screw 103a, the pupil adjustment screw 1041, and the stepped screw 1040 are arranged in substantially the same straight line in the Y direction, and the screw 103b, the screw 103c, and the pupil adjustment screw 1042 are arranged in the substantially same straight line in the Y direction. You may arrange in.

4 Field lens 8 Secondary imaging lens 9 Light receiving sensor 20 Camera body 100 Focus detection unit 101 Fixing member 102 Holding member 103a to 103c Screw 105 Compression coil spring 200 Mirror box 1040 Stepped screws 1041 and 1042 Pupil adjustment screws 1070 to 1072 Mounting surface 1080-1082 Position regulating surface

Claims (4)

A first position-regulating surface that holds a focus detection image sensor and a focus detection optical system that guides incident subject light to the image sensor, and is a plane that is substantially orthogonal to the incident optical axis of the subject light. A holding member having a second position restricting surface and a third position restricting surface;
A fixing member that has the first mounting surface, the second mounting surface, and the third mounting surface to which the holding member is mounted, and is fixed to the apparatus main body of the imaging apparatus;
A first fastening member, a second fastening member, and a third fastening member for fixing the fixing member to the apparatus body;
A regulating member that regulates a distance in the direction of the incident optical axis between the first mounting surface and the first position regulating surface;
A first adjusting member that adjusts an interval in the direction of the incident optical axis between the second mounting surface and the second position regulating surface in a state where the spacing is regulated by the regulating member;
A second adjusting member that adjusts an interval in the direction of the incident optical axis between the third mounting surface and the third position regulating surface in a state where the spacing is regulated by the regulating member;
When the long side direction of the shooting screen is the first direction and the short side direction of the shooting screen is the second direction, the second position restriction surface is more than the first position restriction surface. The third position restricting surface is spaced apart in the second direction, and the third position restricting surface is spaced apart in the first direction with respect to the first position restricting surface,
The first adjustment member, the restriction member, and the first fastening member are arranged in substantially the same straight line along the second direction, and the second fastening member, the second adjustment member, And the third fastening member is substantially the same along the second direction at a position spaced in the first direction with respect to the first adjustment member, the regulating member, and the first fastening member. A focus detection unit arranged in a straight line.   The focus detection unit according to claim 1, wherein the holding member is provided with a notch for fastening the third fastening member.   The distance between the first attachment surface and the first position restriction surface, the distance between the second attachment surface and the second position restriction surface, and the third attachment surface and the third position restriction. 3. The focus detection unit according to claim 1, further comprising: an urging unit that urges each of the surfaces in a direction in which the distance between the surfaces increases. An imaging device comprising a focus detection unit,
An imaging apparatus comprising the focus detection unit according to any one of claims 1 to 3 as the focus detection unit.

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