JP2017053990A - Imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a light leakage at an end part on a subject side of a holding frame.SOLUTION: A semi-transmission mirror holding frame 204 holding a semi-transmission mirror 203 is configured to turn between a mirror-down position where subject light is separated into an imaging device 302 and a finder unit 113 by the semi-transmission mirror 203, using a holding frame turning shaft 32 as a turning center and a mirror-up position where the holding frame 204 retreats from a photographing optical axis 400. A light shield plate 205 retreats from an AE/AF optical path (photographing optical path) passing through the semi-transmission mirror 203 in a mirror-down state, and in a mirror-up state, the light shield plate is positioned oppositely to a rear face of the holding frame 204 and retreats from the photographing optical axis 400. In an entire stroke of turning of the holding frame 204, a first curved surface 204g of an end part 21 of the holding frame 204 and a second curved surface 205b of an end part 22 of the light shield plate 205 are always overlapped in a direction orthogonal to the light shield plate turning shaft 31.SELECTED DRAWING: Figure 8

Description

  The present invention relates to an imaging apparatus having a mechanism for separating subject light into an imaging element and a finder optical system by a semi-transmissive mirror.

  2. Description of the Related Art Conventionally, an imaging apparatus that separates subject light into an image sensor and a finder optical system using a semi-transmissive mirror is known. For example, in a digital single-lens reflex camera in which the subject can be confirmed with an optical finder and the image sensor can be used as an AE / AF sensor, a part of light is transmitted to the image sensor with a semi-transparent mirror placed in the imaging optical path, and the rest Reflects part of the light and directs it to the viewfinder. In this configuration, when the mirror is raised, there is a problem that incident light from the finder enters the mirror box via the semi-transmissive mirror and enters the image sensor to cause flare. In cameras with conventional submirrors, the flare problem has been solved by closing the opening of the holding frame that holds the semi-transparent mirror when the mirror is raised. Measures are necessary.

  As a countermeasure against this, in Patent Document 1, a light shielding member that rotates around the tip of the holding frame of the semi-transparent mirror is driven to a position approaching the holding frame at the mirror up position, and AF at the mirror down position. A configuration that is driven to a position to retract from the AE optical path has been proposed.

Japanese Patent Laid-Open No. 11-295810

  By the way, in order to widen the AE / AF area by the image sensor when the mirror is down, it is necessary to secure a wide opening in the holding frame through which the AE / AF optical path of the semi-transmissive mirror is transmitted. On the other hand, in order to prevent light from the viewfinder from entering the image sensor when the mirror is raised during imaging, the light shielding member needs to have a shape that can reliably shield the opening. Although it is conceivable to increase the area of the light shielding member as the opening is widened, there is a space limitation in the mirror box, which is not easy.

  However, in the prior art disclosed in Patent Document 1, although it is described that the holding frame and the light shielding member are driven in conjunction with each other, the specific relationship between the holding frame and the light shielding member is not described. There has been no detailed study on shading.

  In addition, there is a problem that reverse incident light from the finder is likely to leak from the vicinity of the rotating mechanism between the holding frame and the light shielding member. In particular, the holding frame has a position at the time of shooting operation and a position at the time of AE / AF operation, but it is necessary to prevent light leakage at any position. In considering these countermeasures for light shielding, it is desirable to consider the space saving in the camera. In particular, since there is a region where the interchangeable lens can be accommodated on the subject side of the holding frame, it is desirable to avoid eroding this region as much as possible.

  An object of the present invention is to suppress light leakage at the end of the holding frame on the subject side.

  In order to achieve the above object, the present invention provides a semi-transmission mirror, a first position that holds the semi-transmission mirror, and separates subject light into an image sensor and a finder optical system by the semi-transmission mirror, and a photographing optical path. A holding frame that rotates between a second position for retraction and a rotation shaft provided at an end of the holding frame on the subject side is rotatably supported, and the holding frame is in the first position. An imaging device having a light-shielding member that is retracted from the imaging optical path and overlaps the holding frame when the holding frame is in the second position, and is disposed at the subject side of the holding frame. The first curved surface having a substantially arc shape centering on the rotation axis is formed, and the second curved surface having a substantially arc shape centering on the rotation axis is formed at the subject side end of the light shielding member. Formed between the first position and the second position. In the entire process of the rotation of the lifting frame, wherein the first curved surface and the second curved surface, and wherein the overlapping direction to each other at least partially perpendicular to the pivot shaft.

  According to the present invention, light leakage at the end of the holding frame on the subject side can be suppressed.

It is a schematic diagram of an imaging device. It is an external appearance perspective view of a camera body. It is an external appearance perspective view of the camera main body which has a flash unit in a light emission position. It is a block diagram which shows the function structure of a camera main body. It is a perspective view of a mirror box unit. It is a side view of the structure inside a mirror box, and an image pick-up element. It is a perspective view of a mirror unit. It is a longitudinal cross-sectional view of the mirror unit in the mirror down and up state. It is a longitudinal cross-sectional view of the mirror unit of the modification of a mirror down and an up state.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic diagram of an imaging apparatus according to an embodiment of the present invention. This imaging device is configured as a digital single-lens reflex camera. In this embodiment, a single-lens reflex camera with a detachable lens is exemplified, but the present invention is not limited to this. In other words, the imaging apparatus to which the present invention is applied may be any apparatus that has a mechanism for separating subject light into an imaging element and a finder optical system using a semi-transmissive mirror, and the name is not limited.

  This camera is formed by mounting a replaceable interchangeable lens unit 500 on a camera body 100. As will be described later, the camera body 100 does not include a so-called phase difference AF unit below the mirror box 200 (see FIG. 5), and also includes a reflecting mirror for guiding subject light to the phase difference AF unit. Not. In the mirror box 200, the mirror unit 112 including the semi-transmissive mirror 203 transmits part of the subject light transmitted through the photographing optical system such as the interchangeable lens unit 500 having the optical axis as the photographing optical axis 400, and the imaging element 302. Let the light guide. The mirror unit 112 reflects the remaining subject light and guides it to the finder unit 113 as a finder optical system so that the photographer can observe the subject light. In FIG. 1, illustration of a light shielding plate 205 that is a light shielding member to be described later is omitted.

  2A and 2B are external perspective views of the camera body 100. FIG. FIG. 3 is an external perspective view of the camera body 100 with the flash unit in the light emission position. FIG. 4 is a block diagram illustrating a functional configuration of the camera body 100.

  First, as shown in FIG. 4, the camera microcomputer 10 includes a flash control circuit 11, an operation detection circuit 12, a photographing condition control circuit 13, a motor control circuit 14, an image sensor driving circuit 15, a data processing circuit 16, and a recording processing circuit 17. And the reproduction processing circuit 18 is controlled.

  The camera body 100 includes a top exterior cover 101 and a back exterior cover 111. When the main power switch 107 (FIG. 2B) provided on the upper exterior cover 101 is operated to the ON position, the camera microcomputer 10 starts the camera in a predetermined sequence. When the operation microcomputer 12 detects the operation of the operation member by the operation detection circuit 12, the camera microcomputer 10 performs a corresponding setting. For example, when the shooting mode dial 108 is operated to select a shooting mode, the camera microcomputer 10 sets a program diagram that determines a combination of shutter speed and aperture corresponding to the selected shooting mode. The camera microcomputer 10 also performs settings such as exposure correction when the electronic dial 105 is operated, and sets ISO sensitivity conditions when the ISO sensitivity setting button 106 is operated.

  A series of shooting operations when the automatic setting mode is selected with the shooting mode dial 108 will be described. When it is detected by the operation detection circuit 12 that the release button 104 has been pushed to the first pushing position, the camera microcomputer 10 drives the photographing condition control circuit 13. The camera microcomputer 10 measures subject light by an AE sensor (not shown) provided in the vicinity of the finder unit 113 in order to determine an appropriate shutter speed and aperture value. Note that subject light that has passed through the semi-transmissive mirror 203 and entered the image sensor may be measured.

  When it is determined from the obtained photometric result that the subject light is lower than the predetermined luminance, the camera microcomputer 10 drives the motor control circuit 14 and drives a motor (not shown) to move the flash unit 103 to the light emission position. . Then, the flash unit 103 rotates to the position shown in FIG. When it is detected by the operation detection circuit 12 that the release button 104 has been pushed to the second pushing position, the camera microcomputer 10 drives the motor control circuit 14 so that the subject light reaches the image sensor 302. Then, the mirror unit 112 is retracted to a predetermined position. When the retraction of the mirror unit 112 is completed, the camera microcomputer 10 drives the flash control circuit 11 to emit the flash unit 103 at a predetermined timing and irradiate the subject with appropriate light.

  With the subject light reaching the image sensor 302, the camera microcomputer 10 drives the image sensor drive circuit 15 and acquires the subject light as electronic data by photoelectric conversion. The acquired electronic data is subjected to predetermined data processing such as amplification, conversion, and correction by the data processing circuit 16 to become photographed image data. The camera microcomputer 10 records the obtained photographed image data in a memory (not shown) by driving the recording processing circuit 17. When the photographer operates an image reproduction button (not shown), the camera microcomputer 10 drives the reproduction processing circuit 18 to display the photographed image stored in the memory on the display device 110 provided on the back side. An accessory such as an external strobe can be attached to the accessory shoe 109. The attached external accessory is connected to the circuit inside the camera at the contact point, so that the circuit and the external accessory can communicate with each other.

  FIG. 5 is a perspective view of a mirror box unit including the mirror box 200. A mirror driving unit 201 that drives the mirror unit 112 is fixed to the side surface of the mirror box 200. The mirror drive unit 201 includes a motor, a gear (not shown), a spring, a drive lever, and the like. A finder unit 113 (FIG. 1) is fixed to the upper part of the mirror box 200. The mirror unit 112 that reflects a part of the subject light toward the finder unit 113 includes a semi-transmissive mirror 203, a semi-transmissive mirror holding frame 204, a light shielding plate 205, a biasing toggle spring 206 described later (see FIG. 6A, etc.). ). The semi-transmissive mirror 203 is bonded and fixed to a semi-transmissive mirror holding frame 204 (hereinafter sometimes abbreviated as “holding frame 204”). An antireflection sheet 207 having a known configuration is attached to the inner wall of the mirror box 200 to prevent harmful reflection light. The antireflection sheet 207 is not essential, and an antireflection structure such as antireflection coating may be adopted. An elastic member 208 is fixed to the upper end of the opening of the mirror box 200. When the mirror unit 112 reaches the retracted position, the mirror unit 112 contacts the elastic member 208. The elastic member 208 is made of an elastic material such as sponge or rubber, and alleviates the impact when the mirror unit 112 is driven to the retracted position.

  FIGS. 6A and 6B are side views of the inner structure of the mirror box 200 and the imaging element 302. FIG. The holding frame 204 to which the transflective mirror 203 is fixed is between the first position shown in FIG. 6A and the second position shown in FIG. 6B with the holding frame rotation shaft 32 as the rotation center. Is configured to be rotatable. The holding frame rotation shaft 32 is pivotally supported by the mirror box 200. The first position (hereinafter referred to as a mirror down position) is a position where the photographer observes the subject light and separates the subject light into the image sensor 302 and the finder unit 113 by the semi-transmissive mirror 203. The second position (hereinafter referred to as a mirror-up position) is a position that is taken when the photographer performs photographing and the holding frame 204 is retracted from the photographing optical axis 400. The state of each component of the mirror box 200 when the holding frame 204 is in the mirror down position and the mirror up position is referred to as a mirror down state and a mirror up state, respectively.

  The holding frame 204 rotates between the mirror down position and the mirror up position by being driven by a mirror unit drive lever (not shown) and a mirror unit drive spring, and is stable at each position. It is configured to be holdable. The light shielding plate 205 is formed of a light and strong resin in order to reduce the influence on the operation of the mirror unit 112. Regarding the front and back names of the holding frame 204 and the light shielding plate 205, the upper side at the mirror up position (FIG. 6B) is the front side and the lower side is the back side. Accordingly, the rear surface of the holding frame 204 and the front surface of the light shielding plate 205 face each other at the mirror up position. Antireflection sheets are attached to the front and back of the light shielding plate 205 to reduce reflection of harmful light during focusing and photographing. The antireflection configuration of the light shielding plate 205 is not limited to a sheet, and may be antireflection coating or a shape feature for antireflection.

  A light shielding plate rotation shaft 31 that serves as a rotation center of the light shielding plate 205 is provided at the subject-side end 21 of the holding frame 204. The light shielding plate 205 is rotatably supported on the light shielding plate rotation shaft 31. Accordingly, the light shielding plate 205 rotates relative to the holding frame 204 around the light shielding plate rotation shaft 31. As the holding frame 204 rotates about the holding frame rotation shaft 32, the light shielding plate 205 also rotates. On the side surface of the holding frame 204, a mirror positioning contact surface 204d that contacts the mirror positioning portion 303 provided on the inner surface of the mirror box 200 is provided. When the mirror positioning contact surface 204d contacts the mirror positioning portion 303, the mirror down position of the holding frame 204 is defined. Thereby, the semi-transmissive mirror 203 held by the holding frame 204 is maintained at a predetermined angle. As will be described later with reference to FIG. 7, the light shielding plate 205 is biased in the opening direction with respect to the holding frame 204 in the mirror-down state by the biasing toggle spring 206, and in the closing direction with respect to the holding frame 204 in the mirror-up state. Be forced.

  The image sensor 302 can also perform an AE operation at the same time as performing a focus adjustment operation using a known technique such as contrast AF or imaging surface phase difference AF using the obtained image data. In the present embodiment, since the AE / AF operation is performed in the mirror-down state, the light shielding plate 205 is rotated to a position retracted from the AE / AF optical path (imaging optical path) that passes through the semi-transmissive mirror 203 in the mirror-down state. It is driven dynamically. Further, in the mirror-up state at the time of photographing, the light shielding plate 205 is positioned so as to be opposed to and overlapped with the back surface of the holding frame 204 and is rotated to a position where it is retracted from the photographing optical path.

  7A and 7B are perspective views of the mirror unit 112. FIG. One arm of the urging toggle spring 206 is engaged with the spring engaging shaft 204 f of the holding frame 204, and the other arm is engaged with the spring engaging shaft 205 a of the light shielding plate 205. The biasing toggle spring 206 biases the spring hooking shaft 204f and the spring hooking shaft 205a in directions in which the respective axes are separated from each other. By the urging force of the urging toggle spring 206, the light shielding plate 205 is urged in the opening direction with respect to the holding frame 204 in the mirror down position. However, in the process in which the holding frame 204 is rotated from the mirror down position to the mirror up position, the distance between the arms of the biasing toggle spring 206 is once again expanded, and the vertical axis between the spring hanging shaft 204f and the spring hanging shaft 205a is increased. The positional relationship of is reversed. When the holding frame 204 reaches the mirror-up position, the light shielding plate 205 faces the holding frame 204 and the light shielding plate 205 is urged in the closing direction by the urging force from the urging toggle spring 206.

  The holding frame 204 has an opening 204e. In the mirror down position, subject light transmitted through the opening 204e is received by the image sensor 302 and used for the AE / AF operation. Since the transmission range of the subject light is limited by the opening 204e, the AE / AF possible range on the image sensor 302 is determined by the size of the opening 204e.

  8A and 8B are longitudinal sectional views of the mirror unit 112. FIG. 8A shows a mirror-down state, and FIG. 8B shows a mirror-up state. Each of the holding frame 204 and the light shielding plate 205 has a light shielding shape at the end on the subject side. Specifically, the subject-side end 21 of the holding frame 204 and the subject-side end 22 of the light-shielding plate 205 cooperate to provide a light-blocking function that suppresses light leakage near the end 21 of the holding frame 204. Fulfill. This will be described in detail.

  The end portion 21 of the holding frame 204 has an extending portion 21 a that extends to the back side in the thickness direction of the holding frame 204. By providing the extended portion 21a, the cross-sectional area of the end portion 21 is increased, and the strength of the end portion 21 is improved. The end 21 is formed with a first curved surface 204 g having a substantially arc shape centered on the light-shielding plate rotation shaft 31. The first curved surface 204g is a convex curved surface in a side view. A second curved surface 205 b having a substantially arc shape with the light shielding plate rotation shaft 31 as the center is formed at the end 22 of the light shielding plate 205. The second curved surface 205b is a concave curved surface in a side view. The first curved surface 204g and the second curved surface 205b are formed on substantially concentric circles having different radii around the light-shielding plate rotation shaft 31, and are close to each other with a predetermined gap therebetween.

  In the entire rotation of the holding frame 204 between the mirror down position and the mirror up position, at least a part of the first curved surface 204g and the second curved surface 205b is orthogonal to the light shielding plate rotation shaft 31. It always overlaps the direction (normal direction). That is, in the mirror-down state (FIG. 8A), the curved surfaces 204g and 205b face each other in many areas, and even in the mirror-up state (FIG. 8B), the curved surfaces 204g and 205b face each other. An overlapping area is secured. Normally, in the mirror-down state (FIG. 8A), it is desirable that the image sensor 302 receive only light rays in the AE / AF optical path that pass through the opening 204e of the holding frame 204. It is not preferable that the reverse incident light is incident on the image sensor 302. However, since the curved surfaces 204g and 205b face each other and overlap in the normal direction of the light-shielding plate rotation shaft 31, light shielding near the end 21 of the holding frame 204 is ensured. Thereby, in the mirror-down state, harmful light that affects AE / AF is blocked.

  In the mirror-up state (FIG. 8B), the light-shielding plate 205 prevents the light from the finder unit 113 from passing through the opening 204e of the holding frame 204 and entering the image sensor 302. It is located on the back surface of 204 and is shielded from light. Also at this time, since the curved surfaces 204g and 205b overlap, harmful light incident from the finder unit 113 is prevented from leaking from the vicinity of the end 21 of the holding frame 204, so that harmful light to the image sensor 302 is blocked. .

  The curved surfaces 204g and 205b are substantially concentric, and the clearances between the curved surfaces 204g and 205b are substantially uniform in the circumferential direction around the light-shielding plate rotation shaft 31. Therefore, the rotation of the light shielding plate 205 with respect to the holding frame 204 is not hindered. By the way, the locus L of the tip position of the end portion 21 of the holding frame 204 around the holding frame rotating shaft 32 is shown in FIG. During the entire rotation of the holding frame 204, the tip of the end portion 22 of the light shielding plate 205 does not exceed the locus L and is located closer to the holding frame rotation shaft 32 (inside) than the locus L. Thereby, the arrangement area of the interchangeable lens unit 500 is not affected.

  According to the present embodiment, in the entire rotation of the holding frame 204, the first curved surface 204g of the end portion 21 of the holding frame 204 and the second curved surface 205b of the end portion 22 of the light shielding plate 205 are the light shielding plate. It always overlaps in the direction orthogonal to the rotation shaft 31. Thereby, light leakage at the subject-side end 21 of the holding frame 204 can be suppressed. Therefore, it is possible to suppress the incidence of back incident light from the finder unit 113 to the image sensor 302 at any of the mirror down position and the mirror up position, so that AE / AF and imaging are not affected.

  In addition, since the curved surfaces 204g and 205b are a convex curved surface and a concave curved surface with the light shielding plate rotating shaft 31 as the center, each end of the holding frame 204 and the light shielding plate 205 on the subject side can be configured compactly. Note that the relationship between the convex curved surfaces and the concave curved surfaces of the curved surfaces 204g and 205b may be reversed as long as the effect of suppressing light leakage at the end 21 on the subject side of the holding frame 204 is obtained. The convex and concave curved surfaces of the curved surfaces 204g and 205b are not limited to a continuous circular curved surface, and may be configured as a convex polygon or a concave polygon formed by a plurality of planes.

  The curved surfaces 204g and 205b are included on a virtual circle centered on the light-shielding plate rotation shaft 31, and each virtual circle is a substantially concentric circle. Thereby, the dispersion | variation by the location of the overlapping condition (gap) of the curved surfaces 204g and 205b at the time of rotation of the holding frame 204 can be made small, and the light-shielding effect can be heightened.

  Further, in the entire rotation of the holding frame 204, the tip position of the end portion 22 of the light shielding plate 205 is within the range of the locus L of the tip position of the end portion 21 of the holding frame 204. The accommodation area of the interchangeable lens unit 500 need not be violated.

  Further, since the extending portion 21 a is provided at the end portion 21 of the holding frame 204, the thickness of the end portion 21 can be increased to increase the rigidity of the holding frame 204. In addition, since at least a part of the first curved surface 204g is formed in the extending portion 21a, the extending portion 21a also serves as the first curved surface 204g and contributes to downsizing.

  In this embodiment, regarding the shape of the end portion 22 of the light shielding plate 205, the lower surface of the end portion 22 is formed as a convex curved surface concentric with the second curved surface 205b. However, this is an example, and other shapes can be employed. A modified example relating to this will be described with reference to FIGS.

  FIGS. 9A and 9B are longitudinal sectional views of a modified mirror unit 112. FIG. 9A shows a mirror-down state, and FIG. 9B shows a mirror-up state. An inclined surface 205 d is formed on the back surface of the end portion 22 of the light shielding plate 205. Other configurations are the same as those described with reference to FIGS. Of the back surface of the light shielding plate 205, the back surface of the region other than the end portion 22 is a flat main surface 205c. The inclined surface 205d is also flat, but has an angle different from that of the main surface 205c.

  That is, in the mirror-up state (FIG. 9B), an acute angle formed between the main surface 205c and the photographing optical axis 400 in the side view is an angle θ1, and an acute angle formed between the inclined surface 205d and the photographing optical axis 400 is an angle θ2. . As a magnitude relationship, the angle θ2 is larger than the angle θ1. In an arc-shaped convex curved surface as illustrated in FIG. 8, harmful reflected light is likely to be generated. However, in the modified example illustrated in FIG. 9, harmful reflection on the rear side of the holding frame 204 near the end 21 on the subject side. Light can be suppressed.

  Although the present invention has been described in detail based on preferred embodiments thereof, the present invention is not limited to these specific embodiments, and various forms within the scope of the present invention are also included in the present invention. included.

21, 22 End 31 Shading plate rotation shaft 203 Semi-transmission mirror 204 Semi-transmission mirror holding frame 204g First curved surface 205b Second curved surface 205 Light shielding plate 400 Imaging optical axis

Claims (7)

A semi-transparent mirror,
A holding frame that holds the semi-transmissive mirror and rotates between a first position at which subject light is separated into an image sensor and a finder optical system by the semi-transmissive mirror and a second position that is retracted from the photographing optical path; ,
The holding frame is rotatably supported by a rotating shaft provided at an end portion on the subject side. When the holding frame is in the first position, the holding frame is retracted from the photographing optical path, and the holding frame is the second frame. A light-shielding member that overlaps the holding frame when in the position,
A first curved surface having a substantially arc shape centered on the rotation axis is formed at the end of the holding frame on the subject side,
A second curved surface having a substantially arc shape centered on the rotation axis is formed at the subject side end of the light shielding member,
In the entire rotation of the holding frame between the first position and the second position, at least a part of the first curved surface and the second curved surface is the rotation shaft. An imaging device, wherein the imaging devices overlap in an orthogonal direction.   The imaging apparatus according to claim 1, wherein the first curved surface is a convex curved surface, and the second curved surface is a concave curved surface.   The imaging apparatus according to claim 1, wherein the first curved surface and the second curved surface are formed on a substantially concentric circle with the rotation axis as a center.   In the entire rotation of the holding frame between the first position and the second position, the light shielding member is within the range of the locus of the tip position of the end of the holding frame on the subject side. The imaging apparatus according to claim 1, wherein a tip position of the end portion on a subject side is settled. The light-shielding member has a first surface that is a main surface and a subject-side end portion of the light-shielding member as a back surface that is a surface that does not face the holding frame when the holding frame is in the second position. And at least a second surface formed on
When the holding frame is in the second position, an acute angle formed by the photographing optical axis and the second surface is larger than an acute angle formed by the photographing optical axis and the first surface. The imaging device according to claim 1.   6. The device according to claim 1, wherein the end of the holding frame on the subject side includes an extending portion that extends to a side facing the light shielding member in a thickness direction of the holding frame. The imaging device according to item.   The imaging apparatus according to claim 6, wherein at least a part of the first curved surface is formed in the extending portion.