JP2016212242A - Image-capturing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image-capturing device with which it is possible to suppress harmful reflected light in a photographing optical path without narrowing the exposure area in the image-capturing device of subject light that has passed through a semi-transmissive mirror.SOLUTION: The image-capturing device comprises: a holding frame 204 for holding a semi-transmissive mirror, rotatably supported between a down position and an up position, that transmits a portion of subject light at the down position and guides it to an image-capturing element 302 and reflects the rest of the subject light; a shielding plate 205 rotatably supported to a rotating shaft 204c between a closing position for approaching the holding frame 204 and an opening position for separating from the holding frame 204; and an urging spring 206 for urging the shielding plate 205 to the holding frame 204 in an opening direction, the shielding plate 205 being disposed at the opening position and entering the photographing optical path when the holding frame 204 is at the down position and, with its portion close to the rotating shaft 204c engaged with an engaging part 300 when the holding frame 204 rotates from the down position to the up position, the shielding plate rotating toward the closing position against the urging force of the urging spring 206 and retracting from the photographing optical path.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an imaging apparatus such as a digital single-lens reflex camera including a transflective mirror.

  In an imaging device such as a digital single-lens reflex camera, a part of the subject light that has passed through the lens unit is transmitted through the semi-transmissive mirror and exposed by the imaging device, and the rest of the subject light is reflected by the semi-transmissive mirror to the viewfinder side. Some can observe the subject.

  As such an image pickup device, conventionally, a light shielding member rotatably supported with respect to a holding frame of a semi-transparent mirror is rotated to a position approaching the holding frame at a mirror up position by a biasing force of a toggle spring, and the mirror is lowered. There has been proposed a technique of rotating the position to a position away from the holding frame. In this proposal, the toggle spring is stretched between the mirror box and the light shielding member on the subject side of the holding frame (Patent Document 1).

Japanese Patent Laid-Open No. 11-295810

  However, in Patent Document 1, in order to prevent the toggle spring from interfering with the lens on the image plane side of the lens unit when the semi-transmissive mirror rotates between the mirror-up position and the mirror-down position, Size is limited. For this reason, the semi-transmissive mirror cannot be made large, and the exposure area of the subject light on the image sensor becomes narrow. Further, when the semi-transmissive mirror is rotated to the mirror up position, the toggle spring is exposed to the photographing optical path, so that harmful reflected light may be generated during photographing.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an imaging apparatus capable of suppressing harmful reflected light in a photographing optical path without narrowing an exposure area in an imaging element of subject light transmitted through a semi-transmissive mirror. To do.

  In order to achieve the above object, the imaging apparatus of the present invention is rotatable with respect to the mirror box between a mirror box and a mirror down position that enters the imaging optical path and a mirror up position that retreats from the imaging optical path. A holding member that holds a semi-transmissive mirror that is supported by the mirror and transmits a part of the subject light that has passed through the imaging optical system of the lens unit at the mirror down position, guides the light to the imaging device, and reflects the remainder of the subject light. Driving means for rotating the holding member between the mirror-down position and the mirror-up position, a closed position approaching the holding member with respect to a subject-side tip of the holding member, and the holding member A light-shielding member that is rotatably supported via a pivot shaft between the opening position and the opening position separated from the holding position, and the light-shielding member is provided between the holding member and the light-shielding member. The biasing member that biases the holding member in the opening direction and the light shielding member are disposed at the open position when the holding member is in the mirror down position, and the holding member is moved from the mirror down position to the mirror up position. When rotating to a position, the vicinity of the rotating shaft engages with an engaging portion provided in the mirror box, thereby rotating toward the closed position against the urging force of the urging member. When the holding member is rotated to the mirror up position, the holding member is retracted from the photographing optical path and is arranged at the closed position.

  According to the present invention, harmful reflected light in the photographing optical path can be suppressed without narrowing the exposure region of the subject light flux that has passed through the semi-transmissive mirror.

(A) is the perspective view which looked at the digital single-lens reflex camera which is an example of Embodiment of the imaging device of this invention from the front side, (b) is the perspective view which looked at the digital single-lens reflex camera shown to (a) from the back side. It is. FIG. 2 is a perspective view showing a state in which a strobe unit of the digital single-lens reflex camera shown in FIG. It is a schematic block diagram explaining the control system of the digital single-lens reflex camera shown in FIG. It is a perspective view explaining a mirror box. It is a side view which shows a mirror unit and an image pick-up element. (A) is the perspective view which looked at the mirror unit from the to-be-photographed object side, (b) is the perspective view which looked at the mirror unit from the image pick-up element side. (A) is a side view showing the state of the mirror unit at the mirror-down position, and (b) is a side view showing a state in which the contact portion of the light shielding plate of the mirror unit is in contact with the up position drive pin. It is a side view which shows the state of the mirror unit in a mirror up position. It is a side view explaining the position of a mirror unit when the power switch of a digital single-lens reflex camera is turned off.

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

  FIG. 1A is a perspective view of a digital single-lens reflex camera as an example of an embodiment of an imaging apparatus of the present invention as viewed from the front side, and FIG. 1B is a back view of the digital single-lens reflex camera shown in FIG. It is the perspective view seen from the side. FIG. 2 is a perspective view showing a state in which the strobe unit of the digital single-lens reflex camera shown in FIG. In this embodiment, a digital single-lens reflex camera is exemplified as the imaging device, but the imaging device is not particularly limited as long as the imaging device has a semi-transmissive mirror.

  As shown in FIGS. 1 and 2, the digital single-lens reflex camera 100 of the present embodiment is detachably mounted with an interchangeable lens unit (not shown) on the front side of the camera body 101. On the upper surface of the camera body 101, a flash unit 103, a release button 104, an electronic dial 105, an ISO sensitivity setting button 106, a power switch 107, a mode dial 108, an accessory shoe 109, and the like are provided.

  A display unit 110, a finder unit 113, and the like are provided on the back side of the camera body 101, and a mirror unit 112 is provided inside the camera body 101. The mirror unit 112 is provided in the mirror box 200 (see FIG. 4) and includes a semi-transmissive mirror 203 described later. In the present embodiment, the phase difference AF unit and the reflecting mirror that guides subject light to the phase difference AF unit are not provided below the mirror box 200.

  FIG. 3 is a schematic block diagram for explaining a control system of the digital single-lens reflex camera 100 shown in FIGS. 1 and 2.

  In FIG. 3, when the power switch 107 is turned on, the camera control circuit 10 activates the camera according to a predetermined sequence. When the operation detection circuit 12 detects the operation of the operation member, the camera control circuit 10 performs processing according to the detection result. Execute.

  For example, when the shooting mode is selected by operating the mode dial 108, the camera control circuit 10 sets a program diagram for determining a combination of a shutter speed and an aperture corresponding to the selected shooting mode. The camera control circuit 10 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.

  Next, a series of shooting operations when the automatic setting mode is selected with the mode dial 108 will be described. When the operation detection circuit 12 detects that the release button 104 is half-pressed, the camera control circuit 10 drives the shooting condition control circuit 13. Then, the camera control circuit 10 measures subject light with a photometric sensor (not shown) provided near the viewfinder unit 113 in order to determine an appropriate shutter speed and aperture value. Note that subject light measurement may be performed by measuring subject light that has passed through the semi-transmissive mirror 203 and entered the image sensor 302.

  Next, when the camera control circuit 10 determines that the subject light is lower than a predetermined luminance based on the photometric result of the photometric sensor, the motor control circuit 14 drives a motor (not shown) to pop up the flash unit 103. And move to the light emission position (see FIG. 2).

  Next, when the operation detection circuit 12 detects that the release button 104 is fully pressed, the camera control circuit 10 drives a motor (not shown) by the motor control circuit 14 so that the subject light reaches the image sensor 302. Then, the mirror unit 112 is retracted from the photographing optical path. In addition, the camera control circuit 10 controls the strobe control circuit 11 to emit a strobe at a predetermined timing and irradiate the subject with appropriate light.

  Next, the camera control circuit 10 drives the sensor driving circuit 15 in a state where the subject light reaches the image sensor 302 and acquires subject light as image data by photoelectric conversion, and a data processing circuit for the acquired image data 16 performs predetermined image processing such as amplification, conversion, and correction.

  The camera control circuit 10 drives the recording processing circuit 17 to record the image data after image processing in a memory (not shown). In addition, when the photographer operates a playback button (not shown), the camera control circuit 10 drives the playback processing circuit 18 to display an image recorded in the memory on the display unit 110.

  FIG. 4 is a perspective view for explaining the mirror box 200. As shown in FIG. 4, a drive unit 201 that drives the mirror unit 112 is attached to the side of the mirror box 200. The drive unit 201 includes a motor, a gear, a drive spring, a drive lever, and the like.

  Although not shown, the above-described finder unit 113 is attached to the upper part of the mirror box 200. In addition, a holding frame 204 that holds the semi-transmissive mirror 203 of the mirror unit 112 is rotatably supported by the mirror box 200 via a rotation shaft 204a. The mirror unit 112 includes a light shielding plate 205 and a biasing spring 206 in addition to the semi-transmissive mirror 203 and the holding frame 204. The holding frame 204 corresponds to an example of the holding member of the present invention.

  An antireflection sheet 207 for preventing harmful reflection light is attached to the lower part of the inner wall portion of the mirror box 200. Instead of the antireflection sheet 207, an antireflection coating or an antireflection structure may be employed. In addition, an impact absorbing member 208 that collides with the mirror unit 112 that is mirror-up at the time of photographing is provided on the upper part of the inner wall portion of the mirror box 200. By causing the mirror unit 112 to collide with the impact absorbing member 208, the impact at the time of collision is reduced.

  FIG. 5 is a side view showing the mirror unit 112 and the image sensor 302. As shown in FIG. 5, the holding frame 204 that holds the semi-transmissive mirror 203 can be rotated between a mirror-down position that enters the imaging optical path and a mirror-up position that retreats from the imaging optical path via the rotation shaft 204a. It is supported by.

  Further, the holding frame 204 can be rotated between the mirror down position and the mirror up position by driving the drive shaft 204b with the drive spring and the drive lever of the drive unit 201, and the mirror down position and the mirror up position. It is configured to be held by.

  The semi-transmissive mirror 203 transmits part of the subject light that has passed through the photographing optical system of the lens unit at the mirror down position and guides it to the image sensor 302, and the remaining subject light is directed to the finder optical system side of the finder unit 113. It is configured so that the photographer can observe the subject by reflecting.

  An up position drive pin 300 and a bounce prevention pin 301 are provided on the inner surface of the side wall of the mirror box 200. The up position drive pin 300 corresponds to an example of the engaging portion of the present invention, and the bounce prevention pin 301 corresponds to an example of the contact portion of the present invention. The operations of the up position drive pin 300 and the bounce prevention pin 301 will be described later.

  A light shielding plate 205 is provided at the front end of the holding frame 204 on the subject side. The light shielding plate 205 is supported by the holding frame 204 so as to be rotatable via a rotation shaft 204 c between a closed position approaching the holding frame 204 and an open position spaced apart from the holding frame 204. The light shielding plate 205 corresponds to an example of the light shielding member of the present invention.

  The rotation shaft 204c is provided with a biasing spring 206 that biases the light shielding plate 205 in the direction of opening (leaving) the holding frame 204. In this embodiment, the urging spring 206 is constituted by a torsion spring, the coil portion is inserted into the rotating shaft 204c, one end abuts on the holding frame 204, and the other end abutment portion of the light shielding plate 205 described later. 205d (see FIG. 6). The urging spring 206 corresponds to an example of the urging member of the present invention.

  As shown in FIG. 5, when the mirror unit 112 is disposed at the mirror-down position, the light shielding plate 205 is held by the holding frame 204 with the urging force of the urging spring 206 facing the image sensor 302 side. Is held open (FIG. 5). The distal end portion of the light shielding plate 205 on the imaging element 302 side only needs to have a width sufficient to cover the opening 204f (see FIG. 6B) formed in the holding frame 204, and is on the rotating shaft 204c side (base end side). ). Thereby, the light shielding plate 205 is reduced in weight.

  The light shielding plate 205 shields subject light incident on the image sensor 302 from between the subject-side tip of the holding frame 204 and the lower surface of the mirror box 200 when the mirror unit 112 is disposed at the mirror down position. As a result, the harmful light is shielded from being prevented from deteriorating the image quality obtained by the image sensor 302 so that the focusing accuracy is not affected.

  Antireflection sheets 205a and 205b are attached to both the front and back surfaces of the light shielding plate 205 to prevent harmful light from being reflected during focusing and photographing. When the mirror unit 112 is disposed at the mirror-down position, subject light that has passed through the semi-transmissive mirror 203 enters the image sensor 302 from the opening 204f of the holding frame 204. At this time, if harmful light is reflected by the light shielding plate 205, the image quality deteriorates and the focusing accuracy is affected. However, the harmful reflection light can be reduced by the antireflection sheet 205b. In addition, it may replace with an antireflection sheet | seat and may be light reflection prevention parts, such as antireflection coating and an antireflection shape (for example, continuous shape of an unevenness | corrugation).

  In the present embodiment, the subject light transmitted through the semi-transmissive mirror 203 is converted into an electrical signal by the image sensor 302, and is focused by contrast AF, image plane phase difference AF, or the like using the image data output from the image sensor 302. It is possible to perform an operation. Therefore, it is not necessary to provide a phase difference AF unit below the mirror box 200.

  Further, when the mirror unit 112 is disposed at the mirror down position, the subject light transmitted through the opening 204f of the holding frame 204 is guided to the image sensor 302 to obtain image data. The focusable range is determined. In the present embodiment, the focusable range is not particularly limited, but an opening 204f that is 50% or more of the shooting size is desirable because the focusable range is wide and convenient. Further, when the semi-transmission mirror 203 is small, the opening 204f of the holding frame 204 is also small. Therefore, the semi-transmission mirror 203 is more convenient for the photographer if it is as large as possible.

  6A is a perspective view of the mirror unit 112 viewed from the subject side, and FIG. 6B is a perspective view of the mirror unit 112 viewed from the image sensor 302 side.

  As shown in FIG. 6, an abutting portion 204 d that abuts on a positioning portion 303 (see FIG. 7) provided in the mirror box 200 is provided on the side portion on the distal end side of the holding frame 204. When the abutting portion 204d of the holding frame 204 abuts against the positioning portion 303 of the mirror box 200 at the mirror down position of the mirror unit 112, the semi-transmissive mirror 203 is maintained at a predetermined opening angle.

  In addition, a receiving portion 204 e is provided at the distal end portion of the holding frame 204. The receiving portion 204e has a base end side (rotating shaft 204c side) of the light shielding plate 205 urged in the opening direction with respect to the holding frame 204 by the urging force of the urging spring 206 at the mirror down position of the mirror unit 112. The provided contact portion 205c contacts. As a result, the urging force of the urging spring 206 acting on the light shielding plate 205 is received by the contact portion 205c, and the opening angle of the light shielding plate 205 with respect to the holding frame 204 is maintained.

  The contact portion 205 c of the light shielding plate 205 is formed by being bent away from the holding frame 204. Thereby, the front-end | tip part of the holding frame 204 is reinforced so that the light-shielding plate 205 may contact | abut also in the thickness direction of the front-end | tip part of the holding frame 204. FIG. Note that the contact portion 205c of the light shielding plate 205 is not necessarily formed by being bent.

  Near the rotation shafts 204 c on both sides of the light shielding plate 205 in the width direction, contact portions 205 d that contact the up position drive pins 300 and the bounce prevention pins 301 are provided. In the present embodiment, the contact portion 205d is provided on the reinforcing wall 205e that is erected on both sides of the light shielding plate 205 in the width direction. The up position drive pin 300 is disposed on the upper side (finder side) of the contact portion 205d, and the bounce prevention pin 301 is disposed on the lower side of the contact portion 205d (see FIG. 7).

  Next, the operation of the mirror unit 112 will be described with reference to FIGS. 7A is a side view showing a state of the mirror unit 112 at the mirror down position, and FIG. 7B is a contact portion 205d of the light shielding plate 205 of the mirror unit 112 in contact with the up position driving pin 300. It is a side view which shows a state. FIG. 8 is a side view showing a state of the mirror unit 112 at the mirror up position.

  In the mirror down position of the mirror unit 112 shown in FIG. 7A, the holding frame 204 is held in a state where a predetermined angle is maintained while the contact portion 204d is in contact with the positioning portion 303 of the mirror box 200. Yes. At this time, the bounce prevention pins 301 are spaced apart so as to be in contact with each other with a predetermined gap below the contact portion 205d of the light shielding plate 205. When the mirror unit 112 bounces at the mirror down position, the abutting portion 205d abuts to suppress the bounce of the mirror unit 112.

  In the state shown in FIG. 7A, a part of the subject light that has passed through the photographing optical system of the lens unit is transmitted through the semi-transmissive mirror 203 and enters the image sensor 302, and the remaining part of the subject light is the semi-transmissive mirror 203. Reflects to the viewfinder optical system. As a result, the photographer can observe the subject through the finder optical system.

  The subject light incident on the image sensor 302 is converted into an electrical signal. When the release button 104 is pressed halfway, the above-described focusing control and shooting condition setting are performed by the camera control circuit 10. After the photographing becomes possible, the drive shaft 204b of the holding frame 204 is driven by the drive unit 201, and the holding frame 204 starts to rotate to the mirror up position together with the light shielding plate 205.

  Then, while the holding frame 204 is rotated to the mirror up position, the contact portion 205d of the light shielding plate 205 contacts the up position drive pin 300, and the state shown in FIG. At this time, the position where the abutting portion 205d of the light shielding plate 205 abuts on the up position driving pin 300 is disposed on the subject side with respect to the rotation shaft 204c of the light shielding plate 205. Further, the light shielding plate 205 receives a rotational force from the up position driving pin 300 in the direction of closing (approaching) the holding frame 204 against the urging force of the urging spring 206, so that the light shielding plate 205 is held in the holding frame. It rotates in a closing direction with respect to 204.

  When the holding frame 204 is further rotated to the mirror-up position, as shown in FIG. 8, the tip of the holding frame 204 collides with the impact absorbing member 208 and is held at the mirror-up position. At this time, the light shielding plate 205 is held in a closed state with respect to the holding frame 204 by the up position driving pin 300.

  After the mirror unit 112 is rotated to the mirror-up position, image data is acquired (exposed) by the image sensor 302. At this time, the light shielding plate 205 is held at a position covering the opening 204f of the holding frame 204 while being closed with respect to the holding frame 204, so that harmful light from the finder optical system reaches the image sensor 302. It is preventing. In addition, reflection by harmful light transmitted through the photographing optical system of the lens unit is reduced by an antireflection sheet 205a attached to the light shielding plate 205. As a result, it is possible to reduce harmful light from entering the subject light during exposure of the image sensor 302.

  When the holding frame 204 is rotated to the mirror-down position by the drive unit 201 after the exposure of the image sensor 302, the light shielding plate 205 is moved together with the holding frame 204 to the shooting optical axis as the holding frame 204 approaches the shooting optical axis. Get closer. For this reason, the light shielding plate 205 starts to move away from the up position drive pin 300 and moves away from the holding frame 204 by the biasing force of the biasing spring 206.

  If the mirror unit 112 bounces when the mirror unit 112 is rotated to the mirror down position, the abutting portion 205d of the light shielding plate 205 abuts against the bounce prevention pin 301 as described above. 205 bounces are prevented. Note that when the bounce of the light shielding plate 205 of the mirror unit 112 is small, the bounce prevention pin 301 is not necessarily provided.

  FIG. 9 is a side view for explaining the position of the mirror unit 112 when the power switch 107 of the camera 100 is turned off.

  When the power switch 107 is turned off, the camera control circuit 10 causes the motor control circuit 14 to turn the mirror unit 112 to the vicinity of the mirror up position, and then turns off the camera 100 in a predetermined sequence. . In order to arrange the mirror unit 112 in the vicinity of the mirror up position, the drive lever and the drive cam of the drive unit 201 may be stopped at a predetermined phase. For example, it may be a predetermined phase during the mirror down operation or a predetermined phase during the mirror up operation.

  When the camera control circuit 10 turns off the power supply of the camera 100 with the mirror unit 112 placed in the vicinity of the mirror up position, the holding frame 204 is located in the vicinity of the mirror up position as shown in FIG. Is open with respect to the holding frame 204. That is, the mirror unit 112 can be stopped in a state where the light shielding plate 205 enters the imaging optical path. As a result, even if the photographing lens is inadvertently directed toward sunlight, the light shielding plate 205 can shield sunlight, so that sunlight is not directly incident on a shutter unit (not shown) or the image sensor 302. It becomes possible to do.

  As described above, in this embodiment, when the semi-transmissive mirror 203 rotates between the mirror up position and the mirror down position, the interference between the biasing spring 206 and the lens on the image plane side of the lens unit is taken into consideration. There is no need to do. Further, when the semi-transmissive mirror 203 is rotated to the mirror up position, the biasing spring 206 is not exposed to the photographing optical path. Thereby, harmful reflected light in the photographing optical path can be suppressed without narrowing the exposure region of the subject light that has passed through the semi-transmissive mirror 203 in the imaging element 302.

  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.

DESCRIPTION OF SYMBOLS 100 Digital single-lens reflex camera 112 Mirror unit 200 Mirror box 201 Drive unit 203 Semi-transparent mirror 204 Holding frame 204c Rotating shaft 205 Light-shielding plate 206 Biasing spring 300 Up position drive pin 302 Image sensor

Claims (6)

Mirror box,
An object that is rotatably supported with respect to the mirror box between a mirror-down position that enters the imaging optical path and a mirror-up position that retreats from the imaging optical path, and that has passed through the imaging optical system of the lens unit at the mirror-down position A holding member that holds a semi-transmissive mirror that transmits a part of the light and guides the light to the image sensor, and reflects the remainder of the subject light;
Drive means for rotating the holding member between the mirror down position and the mirror up position;
A light shielding member that is rotatably supported via a rotation shaft between a closed position approaching the holding member and an open position spaced apart from the holding member with respect to a subject-side tip of the holding member;
An urging member that is provided between the holding member and the light shielding member and urges the light shielding member in a direction of opening the holding member;
The light shielding member is disposed in the open position when the holding member is in the mirror down position, and when the holding member rotates from the mirror down position to the mirror up position, the vicinity of the rotation shaft is located near the mirror. By engaging with an engaging portion provided in the box, the urging member rotates toward the closed position against the urging force, and the holding member rotates to the mirror up position. An imaging apparatus, wherein the imaging apparatus is retracted from the imaging optical path and disposed at the closed position.   The imaging apparatus according to claim 1, wherein the light shielding member is disposed at the closed position in a state of covering the semi-transmissive mirror when the holding member is rotated to the mirror up position.   The mirror box is provided with a contact portion that can contact the light shielding member with a gap between the light shielding member when the holding member is rotated to the mirror down position. The imaging device according to claim 1, wherein:   The imaging apparatus according to claim 1, wherein the light shielding member is formed such that a width of a distal end portion is narrower than a base end side on which the rotation shaft is disposed.   The imaging apparatus according to claim 1, wherein a light reflection preventing portion is provided on both surfaces of the light shielding member.   When the power supply of the imaging apparatus is turned off, the holding member is disposed in the vicinity of the mirror up position between the mirror up position and the mirror down position, and the light shielding member is opened with respect to the holding member. The imaging apparatus according to claim 1, wherein the imaging apparatus is disposed at a position that has entered the imaging optical path.