JP3826422B2 - Focus detection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a focus detection apparatus that performs focus detection of an optical apparatus, and more particularly to a focus detection apparatus provided with a plurality of submirrors corresponding to a plurality of focus detection areas.
[0002]
[Prior art]
2. Description of the Related Art In recent years, there have been known cameras that focus on a desired location on an imaging surface without moving the captured composition, or keep track of a subject image that moves on the imaging surface to focus.
Such a camera is equipped with a focus detection device that performs focus detection for a plurality of focus detection areas in order to detect the focus state on the imaging surface in detail.
[0003]
FIG. 14 is a diagram showing this type of focus detection apparatus.
FIG. 15 is a diagram illustrating the arrangement of the focus detection devices in the camera.
In these drawings, a mirror 51m is disposed on the optical axis of the photographing optical system 51 of the camera, and a one-plane sub-mirror 52 is disposed behind the transmission part of the mirror 51m.
[0004]
In the reflection direction of the sub mirror 52, a field mask 53 provided with transmission holes at three positions is arranged. A condenser lens 54 and a mirror 55, in which three lenses are integrally formed, are arranged behind the field mask 53.
In the reflection direction of the mirror 55, an aperture mask 56 that divides each subject light beam that has passed through the field mask 53 and a separator lens 57 that re-images the divided light beams thus divided are arranged. A light receiving element 58 is disposed behind the separator lens 57.
[0005]
In the focus detection apparatus having such a configuration, since one sub-mirror 52 is used, an image space to be formed on the imaging surface side of the camera is directly reflected in the reflection direction, and is an image that is a mirror image of the imaging surface. An equivalent image space is formed on the surface (planar imaging plane) side.
In the field mask 53, transmission holes are arranged at the same scale as the focus detection area on the imaging surface.
[0006]
By such a function of the field mask 53, only the subject light flux that should reach the focus detection area on the imaging surface among the subject light flux that passes through the scheduled imaging plane is transmitted to the condenser lens 54 side.
The condenser lens 54 constitutes a compound lens and shapes the subject luminous flux for each focus detection area. In order to re-image the light beam on the light receiving element 58 without tilting the image plane of the subject light flux, the main plane of the single lens constituting the condenser lens 54 is arranged in a direction parallel to the planned imaging plane.
[0007]
Next, the subject luminous flux for each focus detection area is divided through the aperture mask 56. The divided light beams divided in this way are light beams that intersect at the imaging surface of the subject light beam and whose positional relationship is changed before and after the imaging surface.
The separator lens 57 individually tilts (shifts) these divided light beams to form a set of light images on the light receiving surface of the light receiving element 58. The focus state is detected for each focus detection area based on the interval and positional relationship between the optical images.
[0008]
By the way, the divided light flux that passes through the aperture of the aperture mask 56 is a light flux that passes through the position of the back projection image (hereinafter referred to as “incident pupil”) of the aperture via the condenser lens 54.
If these entrance pupils 51a and 51b are subjected to vignetting (vignetting) of the photographing optical system 51, a part of the divided light flux is lost, which causes a problem in detecting the focus state.
[0009]
For this reason, the entrance pupils 51a and 51b are arranged close to the center side of the photographing optical system 51 so as not to cause vignetting at the periphery of the lens.
In such an arrangement state, as shown in FIG. 14, the symmetry axis of the pair of divided light beams r <b> 2 and s <b> 2 spreads radially from the center side of the photographing optical system 51. For this reason, the light receiving surface of the light receiving element 58 located at the rear is inevitably enlarged.
[0010]
In order to reduce the size of such a light receiving element, a focus detection apparatus in which a light deflecting means is added immediately before or after a condenser lens is also known (Japanese Patent Laid-Open No. 63-278012).
FIG. 16 is a diagram showing a focus detection apparatus having this type of light deflection means.
In the figure, condenser lenses 63M and 63N have front and rear sphere centers decentered from the optical axis O. Therefore, the symmetry axes AM3 and AN3 that are separated from the optical axis O are deflected (shifted) toward the optical axis O.
[0011]
With such a configuration, the separator lens 65 and the light receiving element 66 can be configured in a small size.
[0012]
[Problems to be solved by the invention]
Incidentally, in the conventional example shown in FIG. 14, the divided light beams r <b> 2 and s <b> 2 spread from the optical axis O as the distance from the photographing optical system 51 increases. Therefore, the focus detection device has to secure these optical paths inside, and there is a problem that the entire focus detection device becomes significantly large.
[0013]
In addition, in the conventional example shown in FIG. 16, since the light deflecting means (in FIG. 16, the front shape of the condenser lenses 63M and 63N) is added immediately before the condenser lens 63, the field mask 61 is not downsized at all. I couldn't plan.
Furthermore, since the light deflection means is provided immediately before the condenser lens 63, the distance between the two is short, and in the condenser lens 63, the spread of the optical path (arrangement interval) is hardly reduced. Therefore, it has been impossible to reduce the size of the condenser lens 63 sufficiently.
[0014]
Usually, in the focus detection apparatus, the field mask 61 to the light receiving element 66 are often combined together as an optical block. Since the depth direction of the optical block can be flexibly shortened by optical design, the size of the entire optical block is determined by the size of the frontage.
In the conventional example shown in FIG. 16, since the field mask 61 and the condenser lens 63 are large, the opening of the optical block is large and the entire optical block is large.
[0015]
Further, when the light deflecting unit is added separately from the condenser lens 63, the focus detection device is further increased in size.
Thus, the conventional example shown in FIG. 16 also has a problem that the entire focus detection apparatus is large.
On the other hand, there was a problem in addition to the size of the device.
[0016]
That is, in the conventional example shown in FIG. 14, the symmetry axis of the divided light beams r2 and s2 intersects with the center of gravity of the pair of separator lenses 57 obliquely.
Therefore, the split light beams r2 and s2 are incident on the corresponding separator lens 57 at different angles. As a result, different off-axis aberrations (image surface distortion and the like) are generated in the divided light beams r2 and s2, and an uncorrelated optical image is formed on the light receiving surface of the light receiving element 58.
[0017]
Since the correlation between the image patterns is inferior between such optical images, the positional relationship between the optical images cannot be detected correctly, and the accuracy of focus detection is reduced.
In the conventional example shown in FIG. 16, the divided light beams r3 and s3 pass through the off-axis peripheral portion of the condenser lens 63M. Therefore, various aberrations such as spherical aberration and coma aberration occur in the divided light beams r3 and s3, and the imaging performance on the light receiving surface of the light receiving element 66 is deteriorated. Therefore, there is a problem that the accuracy of focus detection is lowered.
[0018]
In order to solve these problems, it is an object of the present invention to provide a focus detection device that can be miniaturized while improving focus detection accuracy.
In addition to the object of the first aspect, an object of the present invention is to provide a focus detection device capable of further improving the focus detection accuracy.
[0019]
In addition to the object of the first aspect, an object of the present invention is to provide a focus detection device that can be further miniaturized.
In addition to the object of the first aspect, an object of the present invention is to provide a focus detection apparatus capable of accurately correcting the inclination of the planned imaging plane caused by the inward submirror.
[0020]
In addition to the object of the first aspect, an object of the present invention is to provide a focus detection apparatus capable of obtaining high focus detection accuracy irrespective of the inclination of the planned imaging plane by the inwardly facing submirror. And
[0021]
[Means for Solving the Problems]
FIG. 1 is a diagram for explaining the invention described in claim 1.
[0022]
According to the first aspect of the present invention, the sub-mirror 2 and the sub-mirror 2 reflect the subject luminous flux that passes through the photographing optical system 1 of the camera and reaches a predetermined focus detection area on the imaging surface. The reflected light flux that is reflected is divided, and a focus detection optical system 3 that re-images these divided light fluxes individually, and a pair of optical images formed via the focus detection optical system 3 are received by the light receiving surface Z. In the focus detection apparatus including the focus detection unit 4 that performs focus detection of the photographing optical system 1 based on the positional relationship between these optical images, “sub-mirror 2 and focus detection optics” correspond to a plurality of focus detection areas. A plurality of “combinations with the system 3” are provided, and the sub-mirror 2 that reflects the subject luminous flux that reaches the “off-focus detection area S outside the optical axis” is characterized in that the mirror side is arranged inward.
[0023]
According to a second aspect of the present invention, in the focus detection apparatus according to the first aspect, the reflected light beams reflected by the plurality of sub-mirrors 2 are substantially parallel to each other.
FIG. 3 is a diagram for explaining the invention as set forth in claim 3.
According to a third aspect of the present invention, in the focus detection apparatus according to the first aspect, the plurality of submirrors 2 are “focused on the intersection of the incident axis L of the reflected subject light beam and the optical axis O of the photographing optical system 1. It is characterized in that f is located and the rotation axes r are arranged in a direction in contact with the rotary paraboloids P substantially parallel to each other.
[0024]
According to a fourth aspect of the present invention, in the focus detection apparatus according to any one of the first to third aspects, the plurality of sub-mirrors 2 are integrally formed as a polygonal mirror.
According to a fifth aspect of the present invention, in the focus detection apparatus according to any one of the first to third aspects, the focus detection unit 4 may select “a plurality of sets of optical images formed by the plurality of focus detection optical systems 3. Are individually formed on the same substrate.
[0025]
According to a sixth aspect of the present invention, in the focus detection apparatus according to any one of the first to third aspects, in the plurality of focus detection optical systems 3, a plurality of field masks are integrally formed, and a plurality of sets of separator lenses are formed. Are integrally formed, and a plurality of sets of aperture masks are integrally formed.
FIG. 4 is a diagram for explaining the invention as set forth in claim 7.
[0026]
The invention according to claim 7 is the focus detection device according to any one of claims 1 to 6, wherein “the combination of the sub mirror 2 and the focus detection optical system 3 corresponding to the focus detection area S outside the optical axis”. ”, The image plane Im reflecting the imaging surface with the sub mirror 2 as the symmetry plane, the main plane H of the focus detection optical system 3, and the light receiving surface Z of the focus detection means 4 intersect on the same straight line. And
[0027]
FIG. 5 is a view for explaining the invention according to claim 8.
According to an eighth aspect of the present invention, in the focus detection device according to any one of the first to sixth aspects, the focus detection optical system 3 corresponding to the focus detection area S outside the optical axis has a “sub mirror 2 symmetrical. The reflected light beam is divided along the direction of the intersection line T between the “image surface Im reflecting the imaging surface” as the surface and the “light receiving surface Z of the focus detection means 4”.
[0028]
(Function)
In the focus detection apparatus according to the first aspect, a plurality of sub mirrors 2 are provided corresponding to a plurality of focus detection areas.
[0029]
Among the plurality of sub-mirrors 2, the sub-mirror 2 corresponding to the focus detection area S outside the optical axis is arranged in a direction in which the mirror surface side faces inward.
With such a configuration, the incident axis L of the subject luminous flux that spreads radially toward the focus detection area S outside the optical axis is, as shown in FIG. 2, the optical axis O (more precisely, through the sub-mirror 2 in the center). Is reflected closer to the optical axis O.
[0030]
In particular, in such a configuration, since the distance between the sub mirror 2 and the focus detection optical system 3 is long, it is possible to effectively suppress the spread of a plurality of reflected light beams.
By suppressing the spread of the reflected light beam in this way, the interval between the plurality of optical paths in the focus detection optical system 3 is remarkably shortened, and the focus detection device can be further miniaturized.
[0031]
Further, in the field mask 3a and the condenser lens 3b constituting the focus detection optical system 3, since the spread of the reflected light beam is suppressed, the field mask 3a and the condenser lens 3b are also downsized together. Therefore, as compared with the conventional example, the entire focus detection apparatus can be reduced in size efficiently.
On the other hand, when the arrangement interval of the plurality of optical paths secured in the focus detection optical system 3 is set to the same level as the conventional example shown in FIG. 16, the distance between the sub mirror 2 and the focus detection optical system 3 is long. The angle for deflecting the reflected light beam can be reduced. Accordingly, it is possible to reduce the “image plane distortion” and other adverse effects that occur in the reflected light beam to such an extent that they can be ignored.
[0032]
Further, since the reflected light beam is reflected closer to the optical axis O, the incident angle of the separator lens 3c approaches the symmetry of a set of divided light beams obtained by dividing the reflected light beam as shown in FIG.
Accordingly, various off-axis aberrations in the separator lens 3c are generated almost symmetrically, and the correlation is improved with respect to a set of optical images formed on the light receiving surface Z.
[0033]
As a result, the correlation of the optical image pattern is improved, and the positional relationship of the optical image can be detected correctly. Therefore, the focus detection accuracy is improved.
Further, since the reflected light beam is reflected closer to the optical axis O, the reflected light beam is incident almost from the front of the condenser lens 3b as shown in FIG. Therefore, not only the spherical aberration and coma aberration generated in the condenser lens 3b but also the image plane distortion is improved. Therefore, the imaging performance of the optical image on the light receiving surface Z is improved, and the positional relationship of the optical image can be detected with higher accuracy. Therefore, the focus detection accuracy is improved also from this point.
[0034]
In the focus detection apparatus according to the second aspect, the reflected light beams reflected by the plurality of sub-mirrors 2 are substantially parallel to each other.
In such a configuration, since the reflected directions of the reflected light beams are uniform, division and re-imaging can be performed under the same conditions as the focus detection optical system on the optical axis O.
That is, the optical axis of the condenser lens 3b coincides with the symmetry axis of the reflected light beam, and a set of split light beams are incident on the separator lens 3c symmetrically. Therefore, various aberrations occurring in the focus detection optical system 3 outside the optical axis are minimized, and the imaging performance and correlation of the optical image on the light receiving surface Z are maximized. Therefore, the positional relationship of the optical image is correctly detected, and the focus detection accuracy is particularly improved.
[0035]
In the focus detection apparatus according to the third aspect, the intersection point between the incident axis L of the subject light flux and the optical axis O of the photographing optical system 1 is obtained for each sub-mirror 2. Next, a rotating paraboloid P where the focal point f is located at this intersection is assumed.
By arranging the sub mirror 2 in such a direction as to come into contact with the rotating paraboloid P, the reflection direction of the reflected light beam is parallel to the rotation axis r of the rotating paraboloid P.
[0036]
Therefore, the rotational directions r of the paraboloids P assumed for the individual submirrors 2 can be made substantially parallel to each other by making the rotation axes r substantially parallel to each other.
That is, with such an arrangement configuration of the sub mirrors 2, the reflection direction of the reflected light beam can be made uniform in a focus detection area located at an arbitrary position (for example, up, down, left, right, and diagonal) on the imaging surface.
[0037]
As described above, since the reflected directions of the reflected light beams are aligned in a certain direction, various aberrations occurring in the focus detection optical system 3 outside the optical axis are minimized, and the imaging performance of the optical image on the light receiving surface Z and Correlation can be maximized. As a result, the positional relationship of the optical image is correctly detected, and the focus detection accuracy is improved.
In the focus detection apparatus according to the fourth aspect, the plurality of sub-mirrors 2 are integrally configured as a polygon mirror.
[0038]
In the conventional camera, since the sub mirror is composed of one piece, the light leaking from the sub mirror is hardly directly irradiated onto the shutter curtain.
However, when a plurality of sub-mirrors 2 are arranged, light may leak from the gaps between the sub-mirrors 2 and irradiate the shutter curtain.
In this state, if even a slight amount of light leaks from the shutter curtain to the film side, the film is exposed for a long time, and the photographing image quality is significantly impaired. For this reason, the shutter curtain is required to have a higher light shielding property than a normal camera.
[0039]
However, by integrally configuring the plurality of sub-mirrors 2 as a polygon mirror, light leaking from the gap can be reliably and easily prevented. Therefore, there is no risk of deteriorating the image quality of the photographed image, and a shutter curtain having a normal light shielding property can be employed.
Further, since the plurality of sub-mirrors 2 are integrally formed, they can be collectively saved when being retracted outside the photographing optical path. Therefore, the configuration of the mirror drive mechanism for retracting the sub mirror 2 is simplified.
[0040]
Further, since the plurality of sub mirrors 2 are integrally formed, the angle accuracy of the sub mirror 2 is improved and the assembly of the camera is improved as compared with the case where the sub mirrors 2 are incorporated one by one.
[0041]
In the focus detection apparatus according to the fifth aspect, the focus detection apparatus can be miniaturized by forming the light receiving element rows on the same substrate.
In the focus detection device according to the sixth aspect, the components of the focus detection optical system are integrally formed, thereby miniaturizing the focus detection device.
In the focus detection apparatus according to the seventh aspect, first, an image plane Im obtained by mirroring the imaging surface with the plurality of sub-mirrors 2 as symmetry planes is obtained.
[0042]
Usually, these image planes Im have different inclinations because the individual sub-mirrors 2 are arranged at different angles.
When these image planes Im are re-imaged as they are through the focus detection optical system 3, the re-imaging surfaces on the light receiving surface Z also have different inclinations.
Therefore, a clear light image cannot be obtained on the light receiving surface Z, and the focus detection accuracy is lowered.
[0043]
However, in the focus detection apparatus according to the seventh aspect, as shown in FIG. 4, the image plane Im thus obtained, the main plane H of the focus detection optical system 3, and the light receiving surface Z of the focus detection means 4 are provided. Configured to intersect in a straight line.
Due to the inclination of the main plane H, the image plane Im is tilted (tilted), and a re-imaging plane is formed along the light receiving surface Z (Sheimfruk's law).
[0044]
Therefore, a clear light image can be obtained on the light receiving surface Z regardless of the inclination of the image surface Im. As a result, the contrast of the image pattern is increased and the focus detection accuracy is improved.
In FIG. 4, the above-described effect is obtained by inclining the main plane H of the condenser lens 3b. However, the same effect can be obtained by inclining the main plane H of the separator lens group 3c individually. It is done.
[0045]
In the focus detection apparatus according to the eighth aspect, an intersection line T between “an image plane Im obtained by reflecting the imaging surface with the sub mirror 2 as a symmetry plane” and “a light receiving surface Z of the focus detection unit 4” is obtained.
The focus detection optical system 3 divides the reflected light flux in the direction of the intersecting line T. This split light beam forms a set of optical images arranged in the direction of the intersection line T on the light receiving surface Z.
At this time, the image pattern arranged in the direction of the intersection line T on the image plane Im is different from the image pattern arranged in the other direction and is only parallel to the light receiving surface Z. Therefore, the image patterns arranged in the direction of the intersecting line T are re-imaged clearly on the light receiving surface Z through the parallel lens principal plane of the focus detection optical system 3.
[0046]
Therefore, for a set of optical images arranged in the direction of the intersection line T, the correlation between the image patterns can be obtained correctly, and the focus state can be detected with high accuracy.
[0047]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0048]
FIG. 6 is a view showing an embodiment corresponding to claims 1 to 6.
7 to 11 are diagrams showing components and the like constituting the focus detection device.
In these drawings, a mirror 22 is disposed on the optical axis O of the photographing optical system 21 of the camera, and three sub-mirrors 23L, 23M, and 23N are disposed behind the transmission portion of the mirror 22.
[0049]
In the reflection direction of the sub mirrors 23L, 23M, and 23N, as shown in FIG. 8, a field mask 24 provided with transmission holes at three locations is arranged. A condenser lens 25 and a mirror 26 in which three lenses are integrally formed are arranged behind the field mask 24.
A diaphragm mask 27 as shown in FIG. 9 and a separator lens 28 as shown in FIG. 10 are arranged in the reflection direction of the mirror 26. A light receiving element 29 as shown in FIG. 11 is disposed behind the separator lens 28.
[0050]
As for the correspondence relationship between the present invention and the present embodiment, the plurality of submirrors 2 correspond to the submirrors 23L, 23M, and 23N, and the focus detection optical system 3 includes the field mask 24 and the condenser lens 25. , Corresponding to the aperture mask 27 and the separator lens 28, and the focus detection means 4 corresponds to the light receiving element 29.
Here, the arrangement of the sub mirrors 23L to 23N will be described in detail.
[0051]
First, a plurality of focus detection areas are set on the imaging surface (not shown) of the camera. Incidence axes AL1, AM1, and AN1 that are not subject to vignetting of the photographing optical system 21 are determined from the subject light fluxes that respectively reach the plurality of focus detection areas.
Assuming three rotating paraboloids whose focal points are respectively located at the intersections of the incident axes AL1, AM1, AN1 and the optical axis O, and whose rotation axes are parallel to each other, the directions are in contact with these rotating parabolas. Submirrors 23L, 23M, and 23N are arranged, respectively.
[0052]
With such a configuration, the incident axes AL1, AM1, and AN1 are reflected in directions parallel to each other through the three sub-mirrors 23L, 23M, and 23N.
FIG. 12 is a development view showing the optical path of such a reflected light beam.
This figure is a diagram in which the optical path is developed in each incident surface of the sub-mirrors 23L, 23M, and 23N. The incident axis angle θ and the surface angle φ are:
θ = 2φ
Satisfy the relationship.
[0053]
In this way, since the spread of the reflected light beam is suppressed, the focus detection optical system can be downsized.
Further, since the pair of light beams r1 and s1 corresponding to the focus detection area outside the optical axis is symmetric with respect to the axis of the focus detection optical system, the correlation of the optical image formed on the light receiving surface of the light receiving element 29 is obtained. Is secured.
[0054]
FIG. 13 is a diagram showing the inclination of the scheduled image plane.
Since the sub-mirrors 23L, 23M, and 23N are arranged at different angles, the image plane obtained by mirroring the imaging surface with these mirror planes as symmetry planes is slightly inclined.
[0055]
Accordingly, the image plane of the optical image formed on the light receiving surface of the light receiving element 29 is also inclined. Due to such an inclination of the image plane, the image pattern becomes unclear, and the focus detection accuracy is lowered. Such an adverse effect can be easily removed by applying the configuration described in claim 7 or claim 8.
[0056]
【The invention's effect】
As described above, according to the first aspect of the present invention, since the plurality of submirrors are arranged inward, the incident axis of the subject luminous flux that spreads radially is the optical axis (more precisely, the optical axis of the central submirror is the optical axis). Reflected closer to the reflection axis.
[0057]
Therefore, the spread of the reflected light beam can be suppressed to be small, and the focus detection device can be downsized.
In particular, compared to the case where the spread of the reflected light beam is suppressed just before the condenser lens as in the conventional example, the spread of the reflected light beam can be suppressed from a further forward position, so that the spread of the reflected light beam can be further reduced. it can. Therefore, the focus detection device can be further reduced in size.
[0058]
Further, since the spread of the reflected light beam is suppressed from the front of the field mask and the condenser lens constituting the focus detection optical system, the size of these can be reduced. Therefore, it is possible to further reduce the size of the focus detection device and effectively reduce the size.
On the other hand, when the spread of the reflected light beam in the focus detection optical system is made the same as that in the conventional example shown in FIG. 16, the angle at which the reflected light beam is deflected is increased by the longer distance between the sub mirror and the focus detection optical system. Get smaller. Therefore, it is possible to reduce the “image plane distortion” and other adverse effects that occur in the reflected light beam to such an extent that they can be ignored.
[0059]
Further, since the reflected light beam is reflected near the optical axis and is incident on each focus detection optical system from substantially the front, the set of divided light beams obtained by dividing the reflected light beam are positioned substantially symmetrically in the focus detection optical system. pass.
[0060]
Accordingly, various off-axis aberrations respectively generated in the divided light beams are almost symmetrical, and the correlation is improved in a set of optical images formed on the light receiving surface.
As a result, the correlation of the optical image pattern is improved, and the positional relationship of the optical image can be detected with high accuracy. Therefore, the focus detection accuracy is improved.
Further, since the reflected light beam is reflected closer to the optical axis, the reflected light beam passes through the paraxial region of each focus detection optical system. Therefore, not only spherical aberration and coma aberration generated in the reflected light beam, but also image plane distortion is improved. Therefore, the imaging performance of the optical image on the light receiving surface is improved, and the positional relationship of the optical image can be detected correctly. Therefore, the focus detection accuracy is improved also from this point.
[0061]
According to the second aspect of the invention, since the reflected light beams are substantially parallel to each other, division and re-imaging can be performed under the same conditions as the focus detection optical system on the optical axis.
That is, the optical axis of the focus detection optical system coincides with the optical axis of the reflected light beam, and a set of split light beams pass through the focus detection optical system symmetrically.
Therefore, various aberrations occurring in the focus detection optical system outside the optical axis are minimized, and the imaging performance and correlation of the optical image on the light receiving surface are maximized. Therefore, the positional relationship of the optical image is correctly detected, and the focus detection accuracy is particularly improved.
[0062]
In the invention according to claim 3, by arranging the sub mirror in a direction in contact with the paraboloid of revolution, the reflection direction of the reflected light beam can be accurately made substantially parallel.
Therefore, the reflection direction of the reflected light beam can be reliably made substantially parallel also with respect to the focus detection areas located at arbitrary positions (for example, up, down, left, right, and diagonal) on the imaging surface.
[0063]
In the invention according to claim 4, since the plurality of sub-mirrors are integrally formed as a polygon mirror, light leaking from the gap between the sub-mirrors can be reliably and easily prevented.
Therefore, the image quality can be improved without the film being exposed to light leakage for a long time.
[0064]
In addition, since the plurality of sub-mirrors are integrally formed, they can be collectively saved when they are saved outside the photographing optical path. Therefore, the configuration of the mirror drive mechanism for retracting the submirror is simplified.
Further, since the plurality of submirrors are integrally formed, the angle accuracy of the submirrors is improved and the assembly of the camera is improved as compared with the case where the submirrors are incorporated one by one.
[0065]
According to the fifth aspect of the present invention, since the light receiving element array is formed on the same substrate, the focus detection device can be downsized.
According to the sixth aspect of the present invention, since the components of the focus detection optical system are integrally formed, the size of the focus detection device can be reduced.
In the seventh aspect of the invention, as shown in FIG. 4, since the main plane H of the focus detection optical system is tilted, the image plane Im reflected by the submirror is tilted and tilted, and the light receiving surface Z A re-imaging plane is formed along (Sheimfruk's law).
[0066]
Therefore, a clear light image can be obtained on the light receiving surface Z regardless of the inclination of the image surface Im. As a result, the contrast of the image pattern is high, and the focus detection accuracy can be further improved.
In the eighth aspect of the invention, the reflected light beam is divided in the direction of the intersection line T between the “image surface Im obtained by mirroring the imaging surface with the sub mirror as a symmetry plane” and the “light receiving surface Z of the focus detection means 4”.
[0067]
Therefore, these divided light beams form a set of optical images arranged in the direction of the intersecting line T on the light receiving surface Z.
In this state, the image pattern arranged in the direction of the intersection line T on the image plane Im is only parallel to the light receiving surface Z, unlike the image pattern arranged in the other direction. Therefore, a re-imaging surface is formed along the light receiving surface Z without performing tilt imaging.
Therefore, for a set of optical images arranged in the direction of the intersection line T, the correlation between the image patterns can be obtained correctly, and the focus state can be obtained with high accuracy.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining an invention according to claim 1;
FIG. 2 is a diagram showing an optical path of a reflected light beam in claim 1;
FIG. 3 is a diagram for explaining an invention according to claim 3;
FIG. 4 is a view for explaining an invention according to claim 7;
FIG. 5 is a diagram for explaining an invention according to claim 8;
FIG. 6 is a view showing an embodiment corresponding to claims 1 to 6;
FIG. 7 is a view of a planned imaging plane as viewed from above.
FIG. 8 is a pattern diagram of a field mask.
FIG. 9 is a pattern diagram of an aperture mask.
FIG. 10 is a diagram illustrating a separator lens.
FIG. 11 is a diagram showing a pattern of a light receiving element.
FIG. 12 is a development view showing an optical path of a reflected light beam in the embodiment.
FIG. 13 is a diagram showing the inclination of a planned image plane.
FIG. 14 is a diagram showing a conventional focus detection apparatus.
FIG. 15 is a diagram illustrating an arrangement of focus detection devices in a camera.
FIG. 16 is a view showing a focus detection apparatus having a light deflecting unit.
[Explanation of symbols]
1,21 Photography optical system
2,23L ~ N Submirror
3 Focus detection optical system
3a, 24 field mask
3b, 25 condenser lens
3c, 28 Separator lens
4 Focus detection means
22 Quick return mirror
26 Mirror
27 Aperture mask
29 Light receiving element

Claims (8)

A sub-mirror that reflects the subject luminous flux that passes through the imaging optical system of the camera and reaches a predetermined focus detection area on the imaging surface;
A focus detection optical system that divides the reflected light beam reflected by the sub-mirror and re-images these divided light beams individually;
A focus provided with a focus detection unit that receives a set of optical images formed via the focus detection optical system on a light receiving surface and detects the focus of the photographing optical system based on a positional relationship between the optical images. In the detection device,
Corresponding to a plurality of the focus detection areas, a plurality of “combinations of the sub mirror and the focus detection optical system” are provided,
The focus detection device, wherein the sub-mirror that reflects the subject light flux that reaches the “off-focus detection area outside the optical axis” is arranged with the mirror surface facing inward. The focus detection apparatus according to claim 1,
The focus detection device, wherein reflected light beams reflected by the plurality of sub-mirrors are substantially parallel to each other. The focus detection apparatus according to claim 1,
The plurality of submirrors are:
It is respectively arranged in a direction in contact with “a paraboloid in which a focal point is located at an intersection of an incident axis of a reflected subject luminous flux and an optical axis of the photographing optical system, and rotation axes are substantially parallel to each other”. Focus detection device. The focus detection apparatus according to any one of claims 1 to 3,
The plurality of submirrors are:
A focus detection device that is integrally formed as a polygon mirror. The focus detection apparatus according to any one of claims 1 to 3,
In the focus detection means,
A focus detection device, wherein a light receiving element array for individually photoelectrically converting “a plurality of sets of optical images formed by the plurality of focus detection optical systems” is integrally formed on the same substrate. The focus detection apparatus according to any one of claims 1 to 3,
In the plurality of focus detection optical systems,
A plurality of field masks are integrally formed,
A plurality of sets of separator lenses are integrally formed,
A focus detection apparatus, wherein a plurality of sets of aperture masks are integrally formed. The focus detection apparatus according to any one of claims 1 to 6,
For "the combination of the sub mirror and the focus detection optical system" corresponding to the focus detection area outside the optical axis,
An image plane obtained by mirroring the imaging plane with the sub mirror as a symmetry plane, a main plane of the focus detection optical system, and a light receiving surface of the focus detection means intersect on the same straight line. The focus detection apparatus according to any one of claims 1 to 6,
In the focus detection optical system corresponding to the focus detection area outside the optical axis,
A focus detection apparatus that divides the reflected light beam in a direction of intersection between an “image plane obtained by mirroring the imaging surface with the sub mirror as a symmetry plane” and a “light receiving surface of the focus detection unit”.

Images