JP2009180822A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging apparatus capable of adjusting a quantity of light incident on an imaging device and an observation optical system if necessary. <P>SOLUTION: The imaging apparatus includes the imaging device 7, an observation optical system, an optical path switching means 3 and an aperture part 2. The optical path switching means 3 has a light control mirror surface 4 having variable transmittance. The light control mirror surface 4 is set in such a way that the transmittance gets low when reflectance is made high, and the transmittance gets high when the reflectance is made low. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an imaging apparatus such as a single-lens reflex camera, and more particularly to an imaging apparatus using a dimming mirror surface as an optical path switching unit.

Conventionally, as shown in Patent Document 1, a single-lens reflex camera using a half mirror has been proposed. As shown in FIG. 13, the single-lens reflex camera described in this document includes a photographing lens A, a half mirror B, an image sensor C, an optical viewfinder focusing plate D, a pentaprism E, and an eyepiece F. And comprising. Further, the observation optical system is configured by the focusing screen D, the pentaprism E, and the eyepiece lens F.
The half mirror B is attached with an inclination of 45 degrees with respect to the optical axis.
The subject light incident on the photographing lens A is split by the half mirror B. That is, the light that passes through the half mirror B and travels straight is guided to the imaging surface of the imaging element C. Further, the light reflected by the half mirror B in the direction of an angle of 90 degrees with respect to the optical axis is guided to the outside of the single-lens reflex camera via the focusing screen D, the pentaprism E, and the eyepiece F.
JP 2002-182268 A JP 2007-102197 A JP 2003-043203 A

  However, when a half mirror is used in a single-lens reflex camera, the transmittance and reflectance of the half mirror have a constant value. Therefore, there has been a problem that the amount of light incident on the image sensor and the observation optical system cannot be adjusted as necessary.

  The present invention has been made in view of such a problem, and an object thereof is to provide an imaging apparatus capable of adjusting the amount of light incident on the imaging element and the observation optical system as necessary.

  In order to achieve the above object, an imaging apparatus according to the present invention includes an imaging device, an observation optical system, an optical path switching unit, and an opening. The optical path switching unit has a variable transmittance. The light control mirror surface is characterized in that when the reflectivity is increased, the transmittance is decreased, and when the reflectivity is decreased, the transmittance is increased.

  In the imaging device according to the aspect of the invention, the dimming mirror surface has a first state and a second state, and when the dimming mirror surface is in the first state, The incident light beam passes through the dimming mirror surface and enters the imaging element. When the dimming mirror surface is in the second state, the incident light beam is incident on the dimming mirror surface. It is preferable that the light is reflected by the light and enters the observation optical system.

  In the imaging device according to the aspect of the invention, the dimming mirror surface has a first state and a second state, and when the dimming mirror surface is in the first state, The incident light beam passes through the light control mirror surface and enters the observation optical system. When the light control mirror surface is in the second state, the light beam incident from the opening is the light control mirror. It is preferable to reflect on the surface and enter the image sensor.

  In the image pickup apparatus of the present invention, it is preferable that one surface of the optical path switching unit is the light control mirror surface, and the other surface is a surface subjected to antireflection processing.

In the imaging apparatus of the present invention, it is preferable that the light control mirror surface satisfies the following conditional expressions (1) and (2).
0% ≦ Rmax ≦ 10% (1)
0% ≦ Rmin ≦ 10% (2)
Where Rmax is the transmittance at a wavelength of 550 nm when the dimming mirror surface is in the maximum reflection state, and Rmin is the reflectance at a wavelength of 550 nm when the dimming mirror surface is in the maximum transmission state.

In the imaging apparatus of the present invention, the imaging apparatus has a focus detection optical system, and the second optical path switching unit guides the light beam to the focus detection optical system in the optical path transmitted through the optical path switching unit. It is preferable that the dimming mirror surface satisfies the following conditional expressions (3) and (4).
0% ≦ Rmax ≦ 40% (3)
0% ≦ Rmin ≦ 10% (4)
Where Rmax is the transmittance at a wavelength of 550 nm when the dimming mirror surface is in the maximum reflection state, and Rmin is the reflectance at a wavelength of 550 nm when the dimming mirror surface is in the maximum transmission state.

  In the imaging apparatus of the present invention, it is preferable that a gap between the opening and the imaging element is shielded by the optical path switching unit.

  In addition, the imaging apparatus of the present invention includes a shielding member, and the imaging is performed in a space formed by the optical path switching unit and the shielding member, in which the shielding member is in close contact with the optical path switching unit. It is preferable that the element is arranged.

  The image pickup apparatus of the present invention can adjust the amount of light incident on the image pickup element and the observation optical system as necessary.

Hereinafter, embodiments of an imaging apparatus according to the present invention will be described.
The imaging apparatus of the present invention includes an imaging element, an observation optical system, an optical path switching unit, and an opening. Then, an image sensor is arranged on the transmitted light path with respect to the optical path switching means. On the other hand, an observation optical system is disposed on the reflected optical path with respect to the optical path switching means. That is, the light beam incident from the opening enters the optical path switching unit. The light beam that has passed through the optical path switching unit is incident on the image sensor, and the light beam that has been reflected by the optical path switching unit is incident on the observation optical system.
The optical path switching means has a dimming mirror surface with variable transmittance. When the reflectance is increased, the transmittance of the light control mirror surface decreases, and when the reflectance is decreased, the transmittance increases.

  Thus, the transmittance of the light control mirror surface can be adjusted by using the light control mirror surface. That is, when the reflectance of the light control mirror surface is increased, the transmittance is decreased, so that a sufficient amount of light can be supplied to the observation optical system. Further, when the reflectance of the light control mirror surface is lowered, the transmittance is increased, so that a sufficient amount of light can be supplied to the image sensor. Therefore, the amount of light incident on the image sensor and the observation optical system can be adjusted as necessary.

  Further, since the transmittance of the light control mirror surface is variable, it is possible to adjust the light quantity without narrowing the aperture stop even for a bright subject. In other words, since the depth of field becomes shallow, it is possible to shoot with emphasis on the main subject. In addition, since the subject image can be confirmed with the observation optical system while photographing, the release time lag can be reduced. Furthermore, it becomes easy to continuously shoot at high speed.

  The light control mirror surface is, for example, a reflection-type light control element in which a multilayer thin film is formed on a transparent base material as proposed in Patent Document 2, and a transparent conductive film is formed on at least the base material. Forming a layer, an ion storage layer, a solid electrolyte layer, a catalyst layer, and a reflective dimming layer, and applying a voltage and / or passing an electric current between the transparent conductive film layer and the reflective dimming layer, thereby reflecting dimming An all-solid-state reflective dimming electrochromic device that exhibits an action ”.

  Examples of the transparent substrate include glass, a resin sheet, or a combination thereof. A known material can be used for the transparent conductive film layer as long as it is a conductive material. The ion storage layer is preferably a transition metal oxide, such as tungsten oxide, molybdenum oxide, niobium oxide, or vanadium oxide. The solid electrolyte layer is made of a material having a property that protons can be easily moved by voltage application, and examples thereof include tartar oxide and zirconium oxide. Examples of the catalyst layer include materials having high proton permeability, such as palladium, platinum, and palladium alloys. The reflection light control layer is a material that changes into a transparent and mirror shape by absorbing and releasing hydrogen and protons, and is made of an alloy containing magnesium and nickel.

  The dimming mirror surface has a first state and a second state, and when the dimming mirror surface is in the first state, the light beam incident from the opening portion passes through the dimming mirror surface. When the light passes through and enters the image sensor and the dimming mirror surface is in the second state, it is preferable that the light beam incident from the opening is reflected by the dimming mirror surface and enters the observation optical system.

  According to this configuration, when the dimming mirror surface is in the first state, it is possible to increase the amount of light incident on the imaging element and reduce the amount of light incident on the observation optical system. In addition, when the light control mirror surface is in the second state, it is possible to increase the amount of light incident on the observation optical system and decrease the amount of light incident on the image sensor. That is, the amount of light incident on the image sensor and the observation optical system can be adjusted.

  When the dimming mirror surface is in a transparent state (first state), the light beam from the opening is incident on the imaging surface, and when the dimming mirror surface is in a reflecting state (second state), Since the light beam from the aperture enters the observation optical system, a conventional finder optical system can be used. Moreover, the thickness of the body can be reduced by not disposing image inverting means such as a pentaprism on the optical axis of the photographing lens.

  The dimming mirror surface has a first state and a second state, and when the dimming mirror surface is in the first state, the light beam incident from the opening portion passes through the dimming mirror surface. When the light passes through and enters the observation optical system and the dimming mirror surface is in the second state, it is preferable that the light beam incident from the opening is reflected by the dimming mirror surface and enters the image sensor.

In this case, the imaging device, the observation optical system, the optical path switching unit, and the light beam reflected from the light control mirror surface enter the image sensor, and the light beam transmitted through the light control mirror surface enters the observation optical system. It is good to place.
In other words, the image sensor is disposed on the reflected light path with respect to the light control mirror surface. On the other hand, an observation optical system is disposed on the transmitted light path with respect to the light control mirror surface.

  According to this configuration, even if the anti-reflection effect on the other surface (the rear surface of the light control mirror surface) of the optical path switching means is weakened, the captured image is hardly affected, and this is advantageous in terms of configuration and cost. Further, according to this configuration, when the reflectance of the light control mirror surface is increased, the transmittance is decreased, so that a sufficient amount of light can be supplied to the image sensor. Further, when the reflectance of the light control mirror surface is lowered, the transmittance is increased, so that a sufficient amount of light can be supplied to the observation optical system. That is, the amount of light incident on the image sensor and the observation optical system can be adjusted as necessary.

  Moreover, it is preferable that one surface of the optical path switching means is a dimming mirror surface, and the other surface is a surface subjected to antireflection processing.

  The other surface of the optical path switching means may have a reflectance. In such a case, when a subject with a large amount of light is photographed, a ghost image may be photographed due to reflection inside the optical path switching means.

  Here, the reflection on the other surface of the optical path switching means can be prevented by performing the antireflection treatment on the other surface of the optical path switching means. Thereby, since internal reflection in the optical path switching means can be prevented, it is possible to prevent ghost images from being taken. In addition, since the transmittance of the optical path switching unit is increased, a sufficient amount of light can be supplied to the imaging device when a light beam that has passed through the optical path switching unit enters the imaging device.

  Note that the surface subjected to the antireflection treatment may be a known antireflection film or a fine periodic uneven structure (SWS structure) described in Patent Document 3.

In the imaging apparatus of the present invention, it is preferable that the light control mirror surface satisfies the following conditional expressions (1) and (2).
0% ≦ Rmax ≦ 10% (1)
0% ≦ Rmin ≦ 10% (2)
Where Rmax is the transmittance at a wavelength of 550 nm when the dimming mirror surface is in the maximum reflection state, and Rmin is the reflectance at a wavelength of 550 nm when the dimming mirror surface is in the maximum transmission state.

If the upper limit of conditional expression (1) is exceeded, the maximum reflectance of the light control mirror surface will be low, and it will be difficult to make the light beam reflected from the light control mirror surface sufficiently incident on the observation optical system. Therefore, it is difficult to supply a sufficient amount of light to the observation optical system.
If the upper limit of conditional expression (2) is exceeded, the maximum transmittance of the dimming mirror surface will be low, and it will be difficult to sufficiently allow the light beam that has passed through the dimming mirror surface to enter the image sensor. Therefore, it is difficult to supply a sufficient amount of light to the image sensor.

In addition, the imaging apparatus of the present invention has a focus detection optical system, and the second optical path switching unit is arranged in the optical path transmitted through the optical path switching unit so as to guide the light beam to the focus detection optical system. The light control mirror surface preferably satisfies the following conditional expressions (3) and (4).
0% ≦ Rmax ≦ 40% (3)
0% ≦ Rmin ≦ 10% (4)
Where Rmax is the transmittance at a wavelength of 550 nm when the dimming mirror surface is in the maximum reflection state, and Rmin is the reflectance at a wavelength of 550 nm when the dimming mirror surface is in the maximum transmission state.

In this case, the optical path switching by the dimming mirror surface does not have to be complete optical path switching. That is, when photographing a subject, the light beam may be incident on the observation optical system as long as a sufficient light beam is incident on the image sensor. Further, when observing a subject, the light beam may be emitted to the image pickup device via the second optical path switching unit as long as a sufficient light beam is incident on the observation optical system.
If necessary, the light beam to the image sensor may be blocked by a shutter mechanism.

If the upper limit of conditional expression (3) is exceeded, the maximum reflectivity of the light control mirror surface will be low, and it will be difficult to make the light beam reflected by the light control mirror surface sufficiently incident on the observation optical system. Therefore, it is difficult to supply a sufficient amount of light to the observation optical system.
If the upper limit of conditional expression (4) is exceeded, the maximum transmittance of the dimming mirror surface will be low, and it will be difficult to sufficiently allow the light beam that has passed through the dimming mirror surface to enter the image sensor. Therefore, it is difficult to supply a sufficient amount of light to the image sensor.

  In the image pickup apparatus of the present invention, it is preferable that a gap between the opening and the image pickup element is shielded by an optical path switching unit.

A photographing lens can be attached to the opening. Here, when the photographing lens is replaced, dust or the like may enter from the opening. If dust or the like adheres to the image sensor, the obtained image may be deteriorated.
Here, it is possible to prevent dust from adhering to the image pickup device by shielding between the opening of the image pickup device and the image pickup device by the optical path switching means.
In addition, it is preferable to apply a fine periodic concavo-convex structure to the back surface of the light control mirror surface as an antireflection treatment because this surface can be protected.

  The imaging apparatus of the present invention has a shielding member, the shielding member is in close contact with the periphery of the optical path switching unit, and the imaging element is arranged in a space formed by the optical path switching unit and the shielding member. Preferably it is.

The optical path switching means of the present invention can adjust the amount of light incident on the image sensor and the observation optical system as necessary. At this time, since the amount of light is adjusted by changing the transmittance of the light control mirror surface, there is no need to move or flip the light control mirror surface. Therefore, the light control mirror surface can be disposed in close contact with the shielding member. Thereby, the space formed by the optical path switching means and the shielding member can be sealed.
Therefore, it is possible to prevent dust from adhering to the image sensor arranged in this space.

  Next, an embodiment of an imaging apparatus according to the present invention will be described with reference to the drawings.

FIG. 1 shows an example in which the present invention is applied to a single-lens reflex camera (imaging device). The single-lens reflex camera shown in FIG. 1 includes a camera body 1, an opening 2, and a lens barrel 21. The camera body 1 and the lens barrel 21 are connected via the opening 2. A photographing lens 22 is disposed inside the lens barrel 21.
The camera body 1 includes an optical path switching unit 3, a filter 6, an image sensor 7, a focusing screen 8, an image inverting unit 9, and an eyepiece lens system 10. The focusing screen 8, the image reversing means 9, and the eyepiece lens system 10 constitute an observation optical system.

Here, the imaging element 7 is arranged on the transmitted light path with respect to the optical path switching means 3. On the other hand, the observation optical system is arranged on the reflected optical path with respect to the optical path switching means 3.
The optical path switching means 3 is attached with an inclination of about 45 degrees with respect to the optical axis 11. Further, the optical path switching means 3 has a shape of a plane parallel plate.

The optical path switching means 3 includes a first surface 4 and a second surface 5. The first surface 4 is disposed on the opening 2 side. The second surface 5 is disposed on the image sensor 7 side. The first surface 4 is a dimming mirror surface. The second surface 5 is a transmission surface.
The optical path switching means 3 is connected to a control means (not shown). The control means can switch the optical path by controlling the function of the first surface 4 (the dimming mirror surface) as the dimming mirror surface.
The dimming mirror surface 4 exhibits a reflective dimming action by applying a voltage or passing a current.

The dimming mirror surface 4 is an all-solid-state reflective dimming electrochromic element in which a transparent conductive film layer, an ion storage layer, a solid electrolyte layer, a catalyst layer, and a reflective dimming layer using a magnesium-nickel alloy thin film are formed. It is.
Further, the dimming mirror surface 4 has a reduced transmittance when the reflectance is increased, and the transmittance is increased when the reflectance is lowered. In addition, switching can be performed over a wide area.

The filter 6 is configured by an infrared cut filter, a low-pass filter, or the like.
The focusing screen 8 and the image sensor 7 are arranged at positions where the distance from the optical path switching means 3 is substantially equal on the optical axis.
The image inverting means 9 is constituted by a pentaprism, a penta roof mirror, or a combination of a plurality of mirrors.

Reference numeral 11 denotes an optical axis. The luminous flux from the subject enters the photographing lens 22, the opening 2, and the first surface (light control mirror surface) 4 in this order. The light beam that has passed through the light control mirror surface 4 passes through the second surface 5 and the filter 6 in order, and then enters the image sensor 7.
On the other hand, the light beam reflected from the light control mirror surface 4 is incident on the focusing screen 8, the image inverting means 9, and the eyepiece lens system 10 in this order. Accordingly, the subject image can be observed from the eyepiece lens system 10.

Here, when the light control mirror surface 4 is in a high reflectance state, a large amount of light can be supplied to the observation optical system, so that the subject can be observed. In such a state, framing is possible. On the other hand, the dimming mirror surface 4 is in a state where the subject can be photographed by decreasing the reflectance and increasing the amount of transmitted light.
As described above, according to the present embodiment, by providing the light control mirror surface 4, the amount of light incident on the image sensor 7 and the observation optical system can be adjusted as necessary.

It should be noted that the amount of transmitted light does not necessarily have to be 0 when the reflectivity of the light control mirror surface 4 is maximum. In this case, the light beam incident on the image sensor 7 may be shielded using a shutter mechanism (not shown) as necessary. For example, a shutter mechanism (not shown) can be disposed on the imaging lens 22 side of the image sensor 7.
Further, when the transmittance of the light control mirror surface 4 is in the maximum state, the reflectance does not necessarily have to be zero. In this case, an eyepiece shutter (not shown) may be arranged when it is necessary to block the reverse incident light.

  The second surface 5 may be subjected to antireflection processing. In this case, it is possible to prevent internal reflection between the dimming mirror surface 4 and the second surface 5 of the optical path switching unit 3. In particular, the reflectance on the second surface 5 can be made substantially zero by applying the SWS structure described above. As a result, generation of a ghost image due to internal reflection of the optical path switching unit 3 can be prevented.

  2 to 4 schematically show how the SWS structure is applied to the second surface 5. FIG. 2 schematically shows a state in which the SWS structure protrudes in the vertical direction with respect to the second surface 5. FIG. 3 schematically shows how the uneven shape in the SWS structure is oriented in the direction of the optical axis 11. FIG. 4 schematically shows a state in which the maximum angle with respect to the second surface 5 having the uneven shape is the vertical direction. In this case, it is preferable because edging and pressing are facilitated.

  Note that the camera body 1 in this embodiment may have a function of removing dust and the like (so-called dust reduction system).

  FIG. 5 shows an example in which the imaging device of the present application is applied to a camera body and a lens 23 with a far exit pupil is attached. The camera body 1 is the same as that shown in FIG. The lens 23 with a far exit pupil is often used as a telephoto lens having a narrow angle of view and a long focal length, a so-called macro lens that extends an optical system to photograph a large subject. In the present application, since it is not necessary to avoid the optical path switching means 3 from the photographing optical path, a sufficient length can be secured. In other words, the mirror can be made longer than a quick return mirror employed in a conventional single-lens reflex camera, so that the phenomenon of mirror breakage is eliminated. This effect is easier to understand compared to the conventional quick return mirror shown in FIG.

  In addition, the optical path switching by the quick return mirror employed in the conventional single-lens reflex camera as shown in FIG. 11 includes a mechanism for suppressing the impact caused by the mirror jumping up, and a photographing lens system for securing the locus. A large interval between the imaging surfaces must be secured. On the other hand, when the mirror is made smaller, a phenomenon such as vignetting or dimming of the finder image at the upper part of the screen, which is called so-called mirror breakage, occurs particularly in a telephoto lens having a long exit pupil as shown in FIG. The present invention also solves these problems.

  FIG. 6 shows an example in which the present invention is applied to a single-lens reflex camera (imaging device). The same code | symbol as the said Example is used for the member which is common in the said Example. In the present embodiment, the camera body 31 includes a shielding member 36. Specifically, the shielding member 36 is in close contact with the periphery of the optical path switching means 3. A filter 6 and an image sensor 7 are arranged in a space formed by the optical path switching unit 3 and the shielding member 36.

As described above, according to the present embodiment, by providing the light control mirror surface 4, the amount of light incident on the image sensor 7 and the observation optical system can be adjusted as necessary.
Furthermore, according to the present embodiment, the shielding member 36 is provided. Thereby, even when dust or the like enters from the opening 2 when the photographing lens (not shown) attached to the opening 2 is replaced, the filter 6 or the image sensor 7 can be prevented from reaching. That is, according to the present embodiment, it is possible to perform good photographing without adding a function (dust reduction system or the like) for removing dust or the like.
Moreover, it is possible to prevent dust and the like from adhering to the second surface 5. Therefore, when the second surface 5 is subjected to an antireflection treatment, the antireflection function can be kept good.

In particular, when the SWS structure is applied to the second surface 5, it is difficult to remove the attached dust and the like while maintaining the structure. Therefore, since the second surface 5 is arranged on the image sensor 7 side, it is possible to prevent dust and the like from adhering to the second surface 5 to which the SWS structure is applied.
In addition, since the light control mirror surface 4 can be easily cleaned, even if dust or the like is attached, it can be easily removed.
In addition, description of the shielding member 36 of FIG. 6 is drawn symbolically, and is not restricted to this.

FIG. 7 shows an example in which the present invention is applied to a single-lens reflex camera (imaging device). The same code | symbol as the said Example is used for the member which is common in the said Example.
The camera body 41 includes an optical path switching unit 3, a filter 46, an image sensor 47, a focusing screen 48, an image inverting unit 49, and an eyepiece lens system 50. The focusing screen 48, the image inverting means 49, and the eyepiece lens system 50 constitute an observation optical system.

Here, the image sensor 47 is disposed on the reflected light path with respect to the optical path switching means 3. On the other hand, the observation optical system is arranged on the transmission optical path with respect to the optical path switching means 3.
The luminous flux from the subject enters the photographing lens 22, the opening 2, and the first surface (light control mirror surface) 4 in this order. The light beam that has passed through the dimming mirror surface 4 is incident on the second surface 5, the focusing screen 48, the image inverting means 49, and the eyepiece lens system 50 in this order.
On the other hand, the light beam reflected by the light control mirror surface 4 passes through the filter 46 and then enters the image sensor 47.

  The image inverting means 49 is configured by a Porro prism or a combination of a plurality of mirrors. FIG. 8 shows the Porro prism 51.

  Here, when the light control mirror surface 4 is in a low reflectance state, a large amount of light can be supplied to the observation optical system, so that the subject can be observed. In such a state, framing is possible.

On the other hand, when the reflectance of the light control mirror surface 4 is increased, the subject can be photographed.
As described above, according to the present embodiment, by providing the light control mirror surface 4, the amount of light incident on the image sensor 47 and the observation optical system can be adjusted as necessary.

In this embodiment, the image sensor 47 is disposed on the reflected light path with respect to the optical path switching unit 3. Therefore, the light beam reflected by the light control mirror surface 4 does not pass through the second surface 5.
If it does so, the light quantity loss by penetrating the 2nd surface 5 can be prevented.

As in the first embodiment, a shutter mechanism, an eyepiece shutter, or a dust reduction system may be provided as necessary.
Further, the second surface 5 may be subjected to an antireflection treatment.

FIG. 9 shows an example in which the present invention is applied to a single-lens reflex camera (imaging device). The same reference numerals as in the above embodiment are used for members common to the above embodiment.
In the present embodiment, the camera body 61 is provided with a phase difference type focus detection optical system.

  The phase difference focus detection optical system includes a second optical path switching means (mirror) 71, a condenser lens 73, a reflection mirror 74, a pupil division stop 75, a re-imaging lens 76, and a focus detection sensor 77. It is comprised by.

The mirror 71 has a reflecting surface on the photographing lens 22 side.
The position of the mirror 71 is controlled by control means (not shown). Specifically, the mirror 71 can be moved to a position 72. That is, the control means can control the mirror 71 in a state where it is disposed in the optical path and in a state where it is retracted from the optical path. When detecting the focal position, the mirror 71 is disposed in the optical path.
The condenser lens 73 is disposed at a position substantially equivalent to the imaging element 7 with respect to the mirror 71.

When the mirror is arranged at the position 72, since the mirror is not located in the optical path, the light beam that has passed through the optical path switching means 3 enters the image sensor 7.
On the other hand, when the mirror is arranged at the position 71, the mirror is located in the optical path, so that the light beam transmitted through the optical path switching means 3 is reflected by the mirror 71.
The light beam reflected by the mirror 71 enters the condenser lens 73, the reflection mirror 74, the pupil division diaphragm 75, the re-imaging lens 76, and the focus detection sensor 77 in this order.

  When the light control mirror surface 4 is in a high reflectance state, a large amount of light can be supplied to the observation optical system, so that the subject can be observed.

On the other hand, the dimming mirror surface 4 can be photographed by lowering the reflectance, increasing the amount of transmitted light, and retracting the mirror 71 from the optical path (by disposing the mirror at the position 72). Become.
As described above, according to the present embodiment, by providing the light control mirror surface 4, the amount of light incident on the image sensor 7 and the observation optical system can be adjusted as necessary.

In addition, by laying out the phase difference type focus detection optical system on the bottom surface of the camera body 61, the layout in the camera body 61 can be efficiently performed.
Further, it is preferable to perform focus detection based on the light beam transmitted through the optical path switching means 3. That is, it is preferable to dispose the focus detection optical system on the transmission optical path with respect to the optical path switching means 3.

  As in the first embodiment, a shutter mechanism, an eyepiece shutter, or a dust reduction system may be provided as necessary. The second surface 5 may be subjected to antireflection processing.

FIG. 10 shows an example in which the present invention is applied to a single-lens reflex camera (imaging device). In this embodiment, the same phase difference type focus detection optical system as that of the fifth embodiment is arranged in the fourth embodiment. Therefore, the same reference numerals are used for members common to the above-described embodiment.
In the present embodiment, the camera body 81 is provided with a phase difference type focus detection optical system in order to realize fast focusing.

  The phase difference focus detection optical system includes a second optical path switching means (mirror) 91, a condenser lens 73, a reflection mirror 74, a pupil division diaphragm 75, a re-imaging lens 76, and a focus detection sensor 77. It is comprised by.

The mirror 91 is a member of either (a) or (b).
(A) A half mirror having a higher transmittance than the reflectance.
(B) An optical member having a light control mirror surface.
Here, in the case of the member (b), the focus detection accuracy can be increased by increasing the reflectance. In this case, the mirror 91 is connected to a control means (not shown). The control means can switch the optical path by controlling the function of the mirror 91 as the light control mirror surface.
Since the mirror 91 is a member of either (a) or (b), it is easy to perform continuous shooting while adjusting the focus to the subject. It is also possible to follow the subject with the observation optical system as necessary.
The condenser lens 73 is disposed at a position substantially equivalent to the imaging element 47 with respect to the mirror 91.

  The light beam transmitted through the mirror 91 is incident on the focusing screen 48, the image inverting means 49, and the eyepiece lens system 50 in this order. On the other hand, the light beam reflected by the mirror 91 enters the condenser lens 73, the reflection mirror 74, the pupil division diaphragm 75, the re-imaging lens 76, and the focus detection sensor 77 in this order.

In the configuration of FIG. 9, the mirror 71 may be the same as the mirror 91. In this case, the surface of the mirror 91 on the side of the image sensor 7 is preferably an antireflection coating such as an SWS structure.
In FIG. 10, the mirror 91 may be the same as the mirror 71.

In the above-described embodiment, the light amount to the image sensor 7 can be reduced by setting the dimming mirror surface 4 to a half mirror state (a state in which the transmitted light amount and the reflected light amount are substantially equal). For this reason, a high-intensity subject can be favorably photographed.
As another usage, photographing can be performed while observing the subject, and the release time lag can be shortened. In addition, high-speed continuous shooting is possible.

  Further, in the present application, since there is no driving sound of the mirror, it is possible to perform quiet shooting, and shooting in a concert hall or shooting a golf swing during a game becomes easy.

In the present application, the focal position may be detected based on an output signal from the image sensor. With this configuration, since the optical system dedicated to focus detection is not necessary, the configuration of the imaging apparatus can be simplified.
As a focus detection method, a so-called contrast method can be cited.

Specifically, when the focus is detected based on the output signal from the image sensor, the reflectance of the light control mirror surface is set between 30% and 70%. As a result, it is possible to focus while observing the subject with the observation optical system or performing framing.
If the reflectance is lowered from this state, good shooting at low luminance can be performed with a relatively short release time lag. On the other hand, if the reflectance is increased from this state, a bright observation image can be obtained.

It is a figure which shows the single-lens reflex camera which concerns on Example 1 of this invention. It is a side view which shows the example which provided the reflection preventing part in the surface of the optical element. It is a side view which shows the other example which provided the reflection preventing part in the surface of the optical element. It is a side view which shows the other example which provided the reflection preventing part in the surface of the optical element. It is a figure which shows the single-lens reflex camera which concerns on Example 2 of this invention. It is a figure which shows the camera body which concerns on Example 3 of this invention. It is a figure which shows the single-lens reflex camera which concerns on Example 4 of this invention. It is a perspective view of the Porro prism used for the present invention. It is a figure which shows the single-lens reflex camera which concerns on Example 5 of this invention. It is explanatory drawing which shows the single-lens reflex camera which concerns on Example 6 of this invention. It is explanatory drawing which shows the example of the conventional single-lens reflex camera. It is explanatory drawing which shows the other example of the conventional single-lens reflex camera. It is explanatory drawing which shows the other example of the conventional single-lens reflex camera.

Explanation of symbols

1, 31, 41, 61, 81: Camera body 2: Opening portion 3: Optical path switching means 4: First surface (light control mirror surface)
5: Second surface 6, 46: Filter 7, 47: Image sensor 8, 48: Focus plate 9, 49: Image inversion means 10, 50: Eyepiece system 11: Optical axis 21: Lens barrel 22: Shooting lens 23 : Lens with far exit pupil 36: Shielding member 51: Porro prism 71 and 91: Mirror 72: Mirror 71 is retracted from the optical path 73: Condenser lens 74: Reflection mirror 75: Pupil division stop 76: Re-imaging lens 77: Focus detection sensor

Claims (8)

  In an imaging device having an imaging element, an observation optical system, an optical path switching unit, and an opening, the optical path switching unit has a dimming mirror surface with variable transmittance, and the dimming mirror surface is An imaging apparatus, wherein the transmittance decreases when the reflectance is increased, and the transmittance increases when the reflectance is decreased. The dimming mirror surface has a first state and a second state,
When the dimming mirror surface is in the first state, the light beam incident from the opening passes through the dimming mirror surface and enters the image sensor,
The light beam incident from the opening is reflected by the light control mirror surface and enters the observation optical system when the light control mirror surface is in the second state. Imaging device. The dimming mirror surface has a first state and a second state,
When the dimming mirror surface is in the first state, the light beam incident from the opening passes through the dimming mirror surface and enters the observation optical system,
The light beam incident from the opening when the light control mirror surface is in the second state is reflected by the light control mirror surface and enters the image sensor. Imaging device.   The imaging apparatus according to claim 1, wherein one surface of the optical path switching unit is the dimming mirror surface, and the other surface is a surface subjected to antireflection processing. 5. The imaging apparatus according to claim 1, wherein the light control mirror surface satisfies the following conditional expressions (1) and (2): 6.
0% ≦ Rmax ≦ 10% (1)
0% ≦ Rmin ≦ 10% (2)
Where Rmax is the transmittance at a wavelength of 550 nm when the dimming mirror surface is in the maximum reflection state, and Rmin is the reflectance at a wavelength of 550 nm when the dimming mirror surface is in the maximum transmission state. The imaging apparatus includes a focus detection optical system, and a second optical path switching unit is arranged to guide a light beam to the focus detection optical system in an optical path transmitted through the optical path switching unit. 5. The imaging apparatus according to claim 1, wherein the mirror surface satisfies the following conditional expressions (3) and (4).
0% ≦ Rmax ≦ 40% (3)
0% ≦ Rmin ≦ 10% (4)
Where Rmax is the transmittance at a wavelength of 550 nm when the dimming mirror surface is in the maximum reflection state, and Rmin is the reflectance at a wavelength of 550 nm when the dimming mirror surface is in the maximum transmission state.   The imaging apparatus according to claim 1, wherein a gap between the opening and the imaging element is shielded by the optical path switching unit. Having a shielding member,
The periphery of the optical path switching means and the shielding member are in close contact,
The imaging apparatus according to claim 1, wherein the imaging element is arranged in a space formed by the optical path switching unit and the shielding member.

Images