JP2012002920A - Photometric device and imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain high optical performance in a photometric optical system by increasing the positional accuracy of a photometric lens and a photometric aperture in addition to the positional accuracy of the center of a finder screen and the photometric aperture.
A photometric element that measures light from an object, a photometric optical system that makes light from the object incident on the photometric element, an aperture that restricts light from the object that enters the photometric optical system, and an aperture opening Adjust the inclination of the photometric unit with the photometric element, photometric optical system, and aperture stop integrated together, and the center of the aperture opening as the center of rotation, with the center of the light source aligned with the optical axis of the photometric optical system And an adjusting member.
[Selection] Figure 2

Description

  The present invention relates to a photometric device and an imaging device that perform photometry by forming a primary image formed on a finder screen as a secondary image on a photometric element by a photometric optical system.

  In a single-lens reflex camera, it is possible to obtain an image with appropriate exposure by matching the relative positions of the photometric element and the secondary image formed on the photometric element. As a method for adjusting the position of the photometric element, for example, the photometric lens (photometric optical system) and the photometric element are integrally held by a holding member such as a holder, and the relative position between the holding member and the frame to which the holding member is assembled ( There is a method of adjusting an inclination angle (including an inclination angle) with an adjusting member including a screw and a spring (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 06-265966

  When the photometric element described above is used for purposes other than photometry, the positional accuracy between the photometric lens and the photometric aperture, and the positional accuracy between the center of the finder screen and the photometric aperture are important. However, since the aperture for photometry is not assembled to the holding member, the adjustment method using the adjustment member described above maintains the positional accuracy between the center of the finder screen and the aperture for photometry, but the photometric lens and There is a problem that the position accuracy with the aperture for photometry deteriorates and the optical performance of the photometric lens deteriorates.

  In addition to the positional accuracy between the center of the finder screen and the aperture for photometry, the present invention maintains high optical performance in the photometric optical system by increasing the positional accuracy between the photometric lens and the aperture for photometry. It is an object of the present invention to provide a photometric device and an imaging device that can be used.

  In order to solve the above-described problems, a photometric device according to the present invention includes a photometric element that measures light from a target, a photometric optical system that makes light from the target incident on the photometric element, and a photometric optical system. The photometric element, the photometric optical system, and the aperture opening are assembled together in a state where the aperture opening that restricts the light from the target that is incident and the center of the aperture opening coincide with the optical axis of the photometric optical system And a adjusting member for adjusting the inclination of the photometric unit with the center of the aperture opening as the center of rotation.

  The photometric unit preferably includes a lens barrel having the aperture opening, and the photometric optical system preferably maintains a positional relationship with the aperture opening by the lens barrel.

  Moreover, it is preferable that the center of the aperture opening is positioned on an adjustment axis when the inclination is adjusted by the adjustment member.

  Further, the imaging apparatus of the present invention re-images the imaging optical system for imaging light from the object and the light flux of the image by the imaging optical system on the photometric element via the photometric optical system. And a photometric device.

  The photometric element further includes a setting unit in which a plurality of light receiving elements are two-dimensionally arranged, and a part of the plurality of light receiving elements is set as a photometric range in the photometric unit. It is preferable.

  According to the present invention, in addition to the positional accuracy between the center of the finder screen and the aperture for photometry, the positional accuracy between the photometric lens and the aperture for photometry can be increased. The optical performance of the photometric optical system can be maintained with high performance while suppressing variations.

It is a figure which shows the structure of an electronic camera. It is sectional drawing which shows the structure of a photometry unit. 3A is an upper plan view of the photometry unit, and FIG. 3B is a cross-sectional view taken along line FF shown in FIG. 3A. It is a figure which shows the relationship between the center of a finder screen, and the center of a photometry element.

  FIG. 1 shows an outline of an electronic camera 10 as an example of a photographing apparatus of the present embodiment. The electronic camera 10 includes a camera body 11 and a lens unit 12 that can be attached to and detached from the camera body 11. The camera body 11 and the lens unit 12 are each provided with a pair of mounts 13 and 14 that form a male-female relationship. When the lens unit 12 is attached to the camera body 11, the mount 14 provided on the lens unit 12 is coupled to the mount 13 of the camera body 11 by a bayonet mechanism or the like. Each of the mounts 13 and 14 is provided with an electrical contact. When the lens unit 12 is attached to the camera body 11, the electrical contacts provided on the mounts 13 and 14 come into contact with each other to establish an electrical connection between them.

  Next, the configuration of the lens unit 12 will be described. The lens unit 12 includes an imaging optical system 21, a zoom encoder 22, a lens driving unit 23, a diaphragm 24, a diaphragm driving unit 25, a lens microcomputer 26, and the like. The zoom encoder 22, the lens driving unit 23, and the aperture driving unit 25 are each connected to a lens microcomputer 26.

  The imaging optical system 21 includes a plurality of lenses such as a zoom lens 21a and a focus lens 21b. The zoom lens 21a is a lens for adjusting the focal length, and can move in the direction of the optical axis L1 in accordance with the operation of the zoom ring. The zoom encoder 21a is attached to the zoom lens 21a and detects the position of the zoom lens 21a in the direction of the optical axis L1. The focus lens 21b is a lens for adjusting the in-focus position, and can be moved in the direction of the optical axis L1. The lens driving unit 23 drives the focus lens 21b in the direction of the optical axis L1. A distance encoder for detecting a position in the optical axis L1 direction is attached to the focus lens 21b. Detection signals from the zoom encoder 22 and the distance encoder are output to the lens microcomputer 26. The lens microcomputer 26 receives these detection signals and calculates a shooting distance and a focal length at the time of shooting. These calculated values are output to the camera body 11.

  The diaphragm 24 adjusts the amount of light incident on the camera body 11 by opening and closing the diaphragm blades. The diaphragm drive unit 25 controls the aperture of the diaphragm 24. The lens microcomputer 26 communicates with the camera body 11 via the electrical contacts of the mounts 13 and 14 and executes various controls in the lens unit 12. The lens microcomputer 26 transmits lens data recorded in a ROM (not shown) to the camera body 11.

  Incidentally, the lens unit 12 shown in FIG. 1 is merely an example of a configuration of a general zoom lens unit. Therefore, in addition to the lens unit 12 described above, for example, a lens unit 12 that does not have a lens microcomputer, a lens unit 12 of a single focus lens, or the like can be attached to the camera body 11.

  In addition, an example of a so-called single-lens reflex electronic camera 10 in which the lens unit 12 is detachably attached to the camera body 11 is taken up, but the present invention is not limited to this, and the lens unit 12 is fixed to the camera body 11. A so-called compact type electronic camera 10 may be used.

  Next, the configuration of the camera body 11 will be described. The camera body 11 includes a quick return mirror 31, a mechanical shutter 32, an image sensor 33, a sub mirror 34, a focus detection unit 35, a finder optical system, a photometric device 36, and the like. In FIG. 1, the electrical configuration of the camera body 11 is omitted.

  The quick return mirror 31, the mechanical shutter 32, and the image sensor 33 are arranged along the optical axis L <b> 1 of the image pickup optical system 21. A sub mirror 34 is disposed behind the quick return mirror 31. In addition, a finder optical system and a photometric device 36 are arranged on the upper part of the camera body 11. Further, a focus detection unit 35 is disposed in the lower region of the camera body 11.

  The quick return mirror 31 is pivotally supported about a rotation shaft 31a and can be switched between an observation state indicated by a solid line and a retreat state retracted from the optical axis L1. The quick return mirror 31 in the observation state is inclined and disposed in front of the mechanical shutter 32 and the image sensor 33. The quick return mirror 31 in this observation state reflects the light beam that has passed through the imaging optical system 21 upward (in the direction of the optical axis L3) and guides it to the finder optical system. The central portion of the quick return mirror 31 is a half mirror, and a part of the light beam transmitted through the quick return mirror 31 is reflected downward (in the direction of the optical axis L2) by the sub mirror 34 and is reflected on the focus detection unit 35. Led. Note that the focus detection unit 35 performs so-called phase difference detection type focus detection in which an image shift amount of a subject image divided by a separator lens (not shown) is detected for each AF area.

  On the other hand, the quick return mirror 31 in the retracted state is flipped up together with the sub mirror 34 and rotated to a position off the photographing optical path. When the quick return mirror 31 is in the retracted state, the light beam that has passed through the imaging optical system 21 is guided to the mechanical shutter 32 and the imaging element 33.

  The finder optical system includes a finder screen (focus plate) 41, a condenser lens 42, a pentaprism 43, and an eyepiece lens 44. Reference numeral 45 denotes an eyepiece window. The viewfinder screen 41 is located above the quick return mirror 31. The finder screen 41 forms an image of the light beam reflected by the quick return mirror 31 in the observation state. The light beam formed on the finder screen 41 passes through the condenser lens 42 and the pentaprism 43 and is guided to the exit surface having an angle of 90 ° with respect to the incident surface of the pentaprism 43. Then, the light beam from the exit surface of the pentaprism 43 passes through the eyepiece lens 44 and then reaches the user's eyes through the eyepiece window 45.

  A part of the light beam formed on the finder screen 41 passes through the pentaprism 43 and then enters the photometric device 36 via the triangular prism 46. When the optical axis of the light beam reaching the eyepiece lens 44 from the finder screen 41 is L3 and the optical axis of the light beam incident on the photometry device 36 is L4, the optical axis L4 is inclined at an angle θ with respect to the optical axis L3. ing.

  The photometry device 36 is used when performing processing such as face detection and subject tracking in addition to measuring subject light. The photometric device 36 includes a photometric aperture 51, a photometric optical system 52, an IR cut filter 53, and a photometric element 54. The photometric aperture 51 is provided with an aperture (hereinafter referred to as aperture aperture) 51 a at the center thereof, and adjusts the amount of light emitted from the triangular prism 46. The photometric optical system 52 transmits the light beam that has passed through the aperture opening 51 a provided in the photometric aperture 51 and re-images it on the light receiving surface 54 a of the photometric element 54. Hereinafter, a case where the photometric optical system 52 is configured by two lenses (photometric lenses 63 and 64 in FIG. 2) will be described. The IR cut filter 53 absorbs infrared light and transmits light in other frequency regions. The photometric element 54 receives the light beam re-imaged on its light receiving surface. As the photometric element 54, a CCD image sensor or a CMOS image sensor in which a plurality of photodiodes are two-dimensionally arranged is used. The photometric element 54 has a number of pixels that can execute the above-described processing such as face detection and subject tracking.

  Next, the configuration of the photometric device 36 of this embodiment will be described with reference to FIGS. The photometric device 36 of this embodiment includes a photometric unit 60 and a spacer 61. Below, the case where the photometry unit 60 and the spacer 61 which comprise the photometry apparatus 36 are isolate | separated is demonstrated.

  In addition to the above-mentioned photometric aperture 51, photometric optical system 52, IR cut filter 53, photometric element 54, and lens barrel 55, the photometric unit 60 includes a holder 56 in which these members are assembled together. Among the members described above, the lens barrel 55 has an opening 55a, and this opening 55a becomes the aperture opening 51a. That is, the lens barrel 55 has the function of the diaphragm 51 described above in addition to the function of holding the photometric optical system 52.

  The IR cut filter 53 and the photometry element 54 constituting the photometry unit 60 are fixed to the recess 61 provided on the inclined surface 56 a of the holder 56 in the order of the IR cut filter 53 and the photometry element 54. On the other hand, the photometric lenses 63 and 64 constituting the photometric optical system 52 are positioned and held inside the lens barrel 55. The lens barrel 55 in which the photometric lenses 63 and 64 are positioned and held is fixed to the holder 56.

  In a state where the photometric unit 60 is completed, the photometric lenses 63 and 64 constituting the photometric optical system 52 are held between the lens barrel 55 and the holder 56. Among the photometric lenses 63 and 64, the end surface 63a on the triangular prism 46 side of the photometric lens 63 is in contact with the surface 55a of the lens barrel 55 among the end surfaces in the optical axis L4 direction. Further, the end surface 63 b opposite to the end surface 63 a is in contact with the bottom surface 64 b of the recess 64 a provided in the photometric lens 64. Further, the surface 63 c of the photometric lens is brought into contact with the side surface 64 c of the groove 64 a of the photometric lens 64.

  On the other hand, in the photometric lens 64, the outer edge portion of the end face 64 d on the photometric element 54 side is brought into contact with a surface 65 a provided in the concave portion 65 of the holder 56. Of the side surface 64 e of the photometric lens 64, the end on the photometric element 54 side is brought into contact with the wall surface 65 b of the recess 65 provided in the holder 56. Further, of the side surface 64 e of the photometric lens 64, the end on the triangular prism 46 side is in contact with the wall surface 55 b of the lens barrel 55.

  In the state where these photometric lenses 63 and 64 are held, the relative positions of the photometric lenses 63 and 64 and the opening 55a provided in the lens barrel 55 in the direction of the optical axis L4 are fixed. Further, the position of the photometric optical system 52 and the position of the opening 55 a provided in the lens barrel 55 on a plane orthogonal to the optical axis of the photometric optical system 52 are fixed. That is, the optical axes of the photometric lens 63 and the photometric lens 64 coincide, and the center C of the opening 55a provided in the lens barrel 55 is positioned on this optical axis.

  The photometric unit 60 having the above-described configuration is positioned on a frame 70 provided in the camera body 11. After the positioning, the inclination is adjusted with respect to the photometric unit 60 and then fixed. The holder 56 described above is provided with three engagement holes 72a, 72b, 72c through which positioning protrusions 71a, 71b, 71c provided on the upper surface of the frame 70 are respectively inserted. In the top plan view shown in FIG. 3A, the engagement hole 72a and the engagement hole 72b are arranged so that a straight line M connecting the centers of the holes is a straight line parallel to the X direction. The engagement holes 72a and 72b are arranged so that the center C of the opening 55a is located at the midpoint of the straight line M connecting the center of the engagement hole 72a and the center of the engagement hole 72b. Further, the engagement hole 72a and the engagement hole 72c are arranged such that a straight line N connecting the centers thereof is a straight line parallel to the Y direction. That is, the straight line M and the straight line N are two straight lines orthogonal to each other.

  The frame 70 of the camera body 11 is provided with positioning projections 71a, 71b, 71c that are inserted into the engagement holes 72a, 72b, 72c provided in the photometry unit 60 described above. The arrangement relationship of these protrusions 71a, 71b, 71c is the same positional relationship as the engagement holes 72a, 72b, 72c. A plurality of the spacers 61 described above are fitted into the positioning projections 71a, 71b, 71c, and then inserted into engagement holes 72a, 72b, 72c provided in the photometry unit 60, respectively. Thereby, the photometry unit 60 is positioned.

  Next, the inclination adjustment of the photometric unit 60 described above will be described. The inclination of the photometric unit 60 is adjusted by moving the center 81a of the photometric range 81 in at least one direction of the X direction or the Y direction so that the center 81a of the photometric range 81 of the photometric element 54 coincides with the center 41a of the finder screen 41. To be executed. As described above, the photometric unit 60 is positioned via the spacer 61 in each of the positioning projections 71 a, 71 b, 71 c provided on the frame 70. The inclination adjustment of the photometric unit 60 described above is executed by adjusting the thickness of the spacer 61 fitted in each of the protrusions 71a, 71b, 71c. The spacer 61 has the same thickness or a plurality of types of thickness, and the thickness of the spacer 61 is adjusted by stacking a plurality of these.

  As shown in FIG. 4, when a chart paper or the like is photographed using the photometry unit 60 positioned on the frame 70, the center 81a of the photometry range 81 of the photometry element 54 is in the finder in both the X direction and the Y direction. It is assumed that the screen 41 is displaced from the center 41a. As shown in FIG. 3B, in a state in which the photometric unit 60 is positioned on the frame 70, a straight line M passing through the center C of the opening 55a is a spacer positioned between the photometric unit 60 and the frame 70 in the Z direction. It is located within the thickness range of 61.

  When the center 81a of the photometric range 81 in the photometric element 54 is moved in the X direction, one of the following two processes is performed. As a first process, the spacer 61 fitted into the positioning projection 71b is removed to a predetermined thickness, and the spacer 61 having the same thickness as the removed spacer 61 is fitted into the positioning projections 71a and 71c. As a second process, a predetermined number of spacers 61 are fitted into the positioning projections 71b, and of the spacers 61 fitted into the positioning projections 71a and 71c, the spacers are fitted into the positioning projections 71b. Remove the same number of spacers 61 as 61.

  In the positioned photometric unit 60, the center C of the opening 55a is at the midpoint of the straight line M connecting the center of the engagement hole 71a and the center of the engagement hole 71b, and is inserted into and removed from the positioning protrusions 71a and 71c. Since the thickness of the spacer 61 is the same as the thickness of the spacer 61 that is inserted into and removed from the positioning protrusion 71b, the photometric unit 60 passes through the center C of the opening 55a by performing any of the above-described processes. A straight line O parallel to the Y direction is used as an adjustment axis, and the rotation is made about the adjustment axis.

  On the other hand, when moving the center 81a of the photometric range 81 in the photometric element 54 in the Y direction, one of the following two processes is performed. In the first process, the spacer 61 fitted into the positioning projection 71c is removed to a predetermined thickness, and the spacer 61 having the same thickness as the removed spacer 61 is fitted into the positioning projections 71a and 71b. As a second process, a spacer 61 having a predetermined thickness is fitted into the positioning projection 71c, and the spacer 61 fitted into the positioning projections 71a and 71b is fitted into the positioning projection 71c. Remove the spacer 61 having the same thickness as the spacer 61.

  In these cases, since the thickness of the spacer 61 inserted into and removed from the positioning protrusions 71a and 71b is the same as the thickness of the spacer 61 inserted into and removed from the positioning protrusion 71c, one of the above-described processes is performed. Thus, the photometry unit 60 is rotated about the adjustment axis with the straight line M connecting the center of the engagement hole 72a and the center of the engagement hole 72b as an adjustment axis. That is, in the tilt adjustment of the photometry unit 60 that performs the above-described processing, the tilt adjustment with the center C of the opening 55a as the rotation center is executed. By such tilt adjustment, the position accuracy of the center C of the opening 55a serving as the photometric aperture 51 can be kept high with respect to the center of the finder screen 41. As a result, it is possible to suppress the occurrence of a peripheral light amount drop in the photometric element 54 that receives subject light, and to reduce the photometric error. Further, in the photometric unit 60 described above, since the relative positions of the aperture 55a serving as the photometric aperture 51, the photometric optical system 52, and the photometric element 54 are held with high accuracy, a decrease in optical performance can be suppressed.

  In this embodiment, each engagement hole 71a, 71b, 71c is provided so that the center C of the opening 55a can be adjusted as the rotation center, and a straight line connecting the center of the engagement hole 71a and the center of the engagement hole 71b. Each engagement hole is provided on M so that the center C of the opening 55a is located. However, the position of each engagement hole is not limited to the position shown in the drawing as long as the tilt adjustment of the photometry unit 60 with the center C of the opening 55a as the rotation center can be easily performed. That is, the engagement hole 71a can be provided not at the position indicated by the solid line but at the position indicated by the two-dot chain line in FIG. 3A (position indicated by reference numeral 71d).

  In the present embodiment, the photometric lenses constituting the photometric optical system 52 are the two photometric lenses 63 and 64. However, the present invention is not limited to this, and the photometric optical system composed of one photometric lens or three or more photometric lenses It may be a photometric optical system comprising a photometric lens.

  In this embodiment, the lens barrel 55 is provided with an opening 55a, and the opening 55a is used as a diaphragm opening. However, the present invention is not limited to this. For example, a diaphragm opening is formed on one end side of a substantially cylindrical lens barrel. The drawn diaphragm plate may be fixed.

  In the present embodiment, the inclination of the photometric unit 60 is adjusted so that the center 81a of the photometric range 81 of the photometric element 54 coincides with the center 41a of the finder screen 41. A plurality of pixels are two-dimensionally arranged on the light receiving surface 54a of the photometric element 54, and a part of the plurality of pixels arranged two-dimensionally is used as an effective pixel region. That is, in the above-described tilt adjustment of only the photometry unit 60, it is desirable that the effective pixel area provided on the light receiving surface 54a of the photometry element 54 is set to the same size as the photometry range 81.

  However, this is not the case when the effective pixel area in the photometric element 54 is set larger than the photometric range 81. That is, the tilt adjustment of the photometric unit 60 is performed only when at least a part of the photometric range 81 is out of the effective pixel region, and the photometric range is moved into the effective pixel region. Then, after adjusting the inclination of the photometric unit 60, the range used as the photometric range may be adjusted by software using a camera-side microcomputer provided in the camera body 11.

  That is, only when the photometric range is not included in the effective pixel area of the photometric element 54, the above-described tilt adjustment of the photometric unit 54 needs to be executed, and thus the adjustment process of the photometric unit 60 at the time of manufacturing the camera is omitted. be able to. Further, it is possible to maintain a high resolution in the tilt adjustment while suppressing the number of unused pixels in the effective pixel area in the photometric element 54. As a result, the photometric error is reduced, the cost of the photometric element 54 is reduced, and the photometric unit. This can contribute to downsizing of 60.

  In the present embodiment, an example in which the spacer 61 is used as a member for adjusting the inclination of the photometric unit 60 is taken up. However, the member for adjusting the inclination of the photometric unit 60 is not limited to the spacer 61, and a lens barrel. As long as the inclination of the photometry unit 60 can be adjusted with the center C of the 55 aperture (aperture aperture) 55a as the center of rotation, any other adjustment device or adjustment member can be used.

  DESCRIPTION OF SYMBOLS 10 ... Digital camera, 21 ... Imaging optical system, 37 ... Photometry optical system, 41 ... Viewfinder screen, 51 ... Diaphragm, 51a ... Aperture aperture, 52 ... Photometry optical system, 53 ... IR cut filter, 54 ... Photometry element, 55 ... Lens barrel, 55a ... opening, 56 ... holder, 60 ... photometric unit, 61 ... spacer, 63, 64 ... photometric lens, 71a, 71b, 71c ... positioning projection, 72a, 72b, 72c ... engagement hole,

Claims (5)

A photometric element for measuring light from the object;
A photometric optical system for making light from the object incident on the photometric element;
A diaphragm aperture that restricts light from the object incident on the photometric optical system;
A photometric unit in which the photometric element, the photometric optical system, and the aperture opening are assembled together in a state where the center of the aperture opening is aligned with the optical axis of the photometric optical system;
An adjustment member that adjusts the inclination of the photometric unit with the center of the aperture opening as the center of rotation;
A photometric device comprising: The photometric device according to claim 1,
The photometric unit includes a lens barrel having the aperture opening,
The photometric optical system is characterized in that a positional relationship with the aperture stop is maintained by the lens barrel. The photometric device according to claim 1,
The center of the aperture opening is positioned on an adjustment axis when the inclination is adjusted by the adjustment member. An imaging optical system for imaging light from the object;
The photometric device according to any one of claims 1 to 3, wherein a light beam of an image by the imaging optical system is re-imaged on the photometric element via the photometric optical system;
An imaging apparatus comprising: The imaging apparatus according to claim 4,
In the photometric element, a plurality of light receiving elements are arranged two-dimensionally,
An imaging apparatus, further comprising setting means for setting a part of the plurality of light receiving elements as a photometric range in the photometric unit.

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