JP2014232144A - Automatic focus detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem in which the accuracy of focus detection is deteriorated depending on an attachment error of a movable optical element.SOLUTION: In an automatic focus detection device, on the light path between an imaging lens and a focus detection sensor, there are arranged separation means for separating a subject light flux into light corresponding to the wavelength of auxiliary light (auxiliary wavelength corresponding light) and light at least in a part of a wavelength region other than that of the auxiliary wavelength corresponding light (non-auxiliary wavelength corresponding light), first deflection means for deflecting the non-auxiliary wavelength corresponding light obtained through the separation toward a first sensor on the focus detection sensor, and second deflection means for deflecting the auxiliary wavelength corresponding light obtained through the separation toward a second sensor on the focus detection sensor, wherein the first sensor detects a phase difference of an image formed by the non-auxiliary wavelength corresponding light when the auxiliary light is not projected, and the second sensor detects a phase difference of an image formed by the auxiliary wavelength corresponding light when the auxiliary light is projected.

Description

  The present invention relates to a phase difference type automatic focus detection apparatus.

  A single-lens reflex camera or the like is equipped with an automatic focus detection device capable of automatic focus detection by a phase difference method, for example. The phase difference method is a method of irradiating a pair of subject images divided by pupils onto a focus detection sensor and obtaining defocus from the phase difference of the pair of subject images on the focus detection sensor. Specifically, it is determined to be in focus when the distance between the pair of subject images formed on the focus detection sensor is a predetermined length, determined to be a front pin when shorter than a predetermined length, and determined to be a rear pin when longer than a predetermined length. Then, the amount of focus deviation from the in-focus position is output as the defocus amount.

  As a focus detection sensor of this type of focus detection apparatus, a light receiving element having sensitivity in a visible region and a longer wavelength region (for example, near infrared region) may be used. In this case, different focus detection is performed for light of different wavelengths due to chromatic aberration of a photographing lens such as a single-lens reflex camera. For example, the longer the wavelength, the greater the chromatic aberration. Therefore, when the same subject is illuminated with a light source with a low color temperature such as a tungsten lamp, and when illuminated with a light source with a high color temperature such as daylight or a fluorescent lamp, the latter The former is more likely to be determined as the front pin. In general, the photographic aberration tends to increase the chromatic aberration as the focal length increases. Therefore, particularly the telephoto lens tends to have a large focus detection error due to the chromatic aberration.

  In order to reduce this kind of focus detection error, an optical filter that cuts light in a wavelength region longer than the visible region is usually installed in front of the focus detection sensor. As a result, focus detection is performed in a state in which the influence of chromatic aberration in a long wavelength region such as the near infrared region due to the photographing lens is eliminated. On the other hand, the auxiliary floodlight that emits light at low luminance uses light in the red or near-infrared wavelength region so that the subject (person) does not feel glare. In this case, if light in a long wavelength region such as the near-infrared region is cut, an auxiliary floodlight that emits light at low luminance cannot be used. In view of such circumstances, Patent Document 1 discloses that an optical filter that transmits light in the near-infrared region at the time of irradiation of the auxiliary projection lamp is inserted in the optical path, and near-infrared when the auxiliary projection lamp is not used. An apparatus for inserting an optical filter for cutting light in a region into an optical path has been proposed.

Japanese Patent Publication No. 8-3575

  However, in the configuration described in Patent Document 1, it is considered that the optical filter needs to be attached to a guide mechanism such as a slide rail so that the optical filter that is an optical element can be moved with respect to the optical path. In Patent Document 1, since it is necessary to attach an optical filter via such a movable mechanism, an attachment error (for example, an inclination error) of the optical filter with respect to another optical element may change every time it is movable. Therefore, the focus detection accuracy may be deteriorated depending on the position accuracy of the optical filter.

  An automatic focus detection apparatus according to an aspect of the present invention is an automatic focus detection apparatus for a photographing apparatus capable of projecting auxiliary light toward a subject, and the subject light flux that passes through a photographing lens of the photographing apparatus. By dividing and forming at least a pair of subject images on focus detection sensors in different detection areas, the phase difference between at least a pair of images is detected, and the focus position of the subject is detected based on the detected phase difference. In the optical path between the photographic lens and the focus detection sensor, at least a part of the subject luminous flux corresponding to the wavelength of the auxiliary light (auxiliary wavelength compatible light) and at least a part other than the auxiliary wavelength compatible light Separating means that separates light in a wavelength range (non-auxiliary wavelength compatible light) and first deflection that deflects the non-auxiliary wavelength compatible light separated by the separating means toward the first sensor on the focus detection sensor Means and separation means A second deflecting unit configured to deflect the separated auxiliary wavelength-corresponding light toward a second sensor different from the first sensor on the focus detection sensor, and when the auxiliary light is not projected by the photographing apparatus The first sensor detects the phase difference of the image made up of non-auxiliary wavelength compatible light, and the second sensor detects the phase difference of the image made up of auxiliary wavelength compatible light when the imaging device projects the auxiliary light.

  According to one aspect of the present invention, an increase in focus detection error due to aberrations such as near-infrared light is suppressed when the auxiliary projection lamp is not projecting while an effect of insufficient luminance improvement is obtained when the auxiliary projection lamp is projected. In order to achieve the purpose, there is no need to move an optical element such as an optical filter or an optical lens with respect to the optical path. Therefore, there is no possibility that the focus detection accuracy is deteriorated depending on the mounting error (positional accuracy) of the optical element configured to be movable.

  The separating unit and the first deflecting unit are formed on the same surface, for example. The same surface on which the separating unit and the first deflecting unit are formed is a half mirror surface that transmits auxiliary wavelength-corresponding light in the subject light flux and reflects non-auxiliary wavelength-corresponding light toward the first sensor. Also good.

  In addition, the second deflecting unit is a mirror surface arranged so as to reflect the auxiliary wavelength corresponding light transmitted through the half mirror surface toward the second sensor, for example.

  Further, the automatic focus detection device may be configured to include a wedge-shaped flat plate. In this flat plate, the first surface on the photographing lens side is a half mirror surface, and the second surface opposite to the first surface, which is disposed at a predetermined angle with respect to the first surface, is a mirror surface.

  In addition, the automatic focus detection device is arranged behind the condenser lens and the condenser lens disposed behind the planned focal plane of the photographing lens, and re-images the subject image on the planned focal plane on the focus detection sensor. At least two pairs of separator lenses, a first aperture pair corresponding to at least a pair of separator lenses disposed on the light path toward the first sensor, and on the incident side of the separator lens, and toward the second sensor It is good also as a structure provided with the separator mask which has the 2nd opening pair corresponding to at least a pair of separator lens arrange | positioned on an optical path. In this configuration, the separating unit and the first and second deflecting units are disposed, for example, in the optical path between the condenser lens and the separator mask.

  In addition, the automatic focus detection device has a filter that transmits non-auxiliary wavelength compatible light and reflects or absorbs auxiliary wavelength compatible light disposed on the first aperture pair to transmit auxiliary wavelength compatible light and non-auxiliary wavelength compatible. A filter that reflects or absorbs light may be arranged on the second pair of openings.

  The non-auxiliary wavelength compatible light includes, for example, at least part of light in the visible region.

  According to the automatic focus detection apparatus according to an aspect of the present invention, a focus detection error due to aberrations such as near infrared is obtained when the auxiliary projection lamp is not projecting while obtaining an effect of insufficient luminance at the time of projection. In order to achieve the purpose of suppressing the increase of the optical element, there is no need to move an optical element such as an optical filter or an optical lens with respect to the optical path. Therefore, there is no possibility that the focus detection accuracy is deteriorated depending on the mounting error (positional accuracy) of the optical element configured to be movable.

It is a block diagram which shows the structure of the imaging device of embodiment of this invention. It is a perspective view which expands | deploys an optical path and shows arrangement | positioning of each element which comprises the automatic focus detection module mounted in the imaging device of embodiment of this invention. It is a figure which shows arrangement | positioning of each element which comprises the automatic focus detection module of embodiment of this invention (optical path non-development). It is a figure which shows the spectral reflectance characteristic of the half mirror surface of the flat plate with which the automatic focus detection module of this embodiment was equipped. It is a figure which shows the flowchart of the interlocking process of an auxiliary light projection lamp and a focus detection element.

  Hereinafter, with reference to the drawings, a photographing apparatus equipped with an automatic focus detection apparatus according to an embodiment of the present invention will be described.

[Entire configuration of the photographing apparatus 1]
FIG. 1 is a block diagram showing a configuration of the photographing apparatus 1 of the present embodiment. The photographing apparatus 1 of the present embodiment is a digital single-lens reflex camera (with a quick return mirror), but a mirrorless single-lens camera, a compact digital camera, a camcorder, a mobile phone terminal, a PHS (Personal Handy phone System), a smartphone, and a feature phone. It may be replaced with another type of photographing device having a photographing function such as a portable game machine.

  As shown in FIG. 1, the photographing apparatus 1 includes a camera body 10 and an interchangeable lens 50 that can be exchanged by being attached to and detached from the camera body 10. The luminous flux from the subject (subject luminous flux) is reflected by the main mirror 11 in the camera body 10 through the photographing lens 51 in the interchangeable lens 50 toward the pentaprism 12 constituting the finder optical system. It is reflected and emitted from the fine loupe 13. The photographer can observe the subject image by looking through the fine loupe 13. A part of the main mirror 11 is a half mirror region. Therefore, a part of the subject luminous flux passes through the main mirror 11 (half mirror region) and is reflected downward by the sub-mirror 14 provided on the back surface of the main mirror 11, and is thus an automatic focus detection device (auto focus detection module). 100 is incident.

  The automatic focus detection module 100 detects the focus state of the subject and outputs a signal corresponding to the detection result to the body CPU 20. The body CPU 20 performs a defocus calculation based on the signal input from the automatic focus detection module 100, and adjusts the focus of the photographing lens 51 based on the defocus amount obtained by the calculation. Since this type of focus adjustment is well known, a detailed description thereof will be omitted. Further, in FIG. 1, the electrical connection of each block is omitted for the sake of simplicity of the drawing.

  When a release switch (not shown) is pressed, the body CPU 20 causes the main mirror 11 to return quickly. That is, the body CPU 20 raises the main mirror 11 and the sub mirror 14 and is parallel to the optical axis AX of the photographing lens 51 only during a period immediately before the start of the front curtain travel of the focal plane shutter (not shown) and immediately after the end of the rear curtain travel. The subject image is formed on the image sensor 15 by retracting the main mirror 11 and the sub-mirror 14 from the light path. The image sensor 15 is, for example, a CCD (Charge Coupled Device) image sensor or a CMOS (Complementary Metal Oxide Semiconductor) image sensor, and accumulates an optical image formed by each pixel on the imaging surface as a charge corresponding to the amount of light to capture an image. Convert to signal. The converted imaging signal is stored in a memory (not shown) as an image through predetermined processing by an image processing circuit (not shown). The photographer can view the photographed image through an LCD monitor (not shown) provided on the back of the camera body 10.

  The body CPU 20 causes the auxiliary floodlight 30 to emit light when it is determined that the subject has low brightness based on the output of a photometric sensor (not shown). In the auxiliary light projection by the auxiliary light projection lamp 30, light in the wavelength range of red or near infrared is used so that the subject (person) does not feel glare.

[Configuration of Automatic Focus Detection Module 100]
FIG. 2 is a perspective view showing the arrangement of the elements constituting the automatic focus detection module 100 with the optical path developed. The autofocus detection module 100 is an autofocus detection module that employs a phase difference method, and as shown in FIG. 2, a condenser lens 101, a separator mask 102, a separator lens 103, a focus detection element 104, an auxiliary wavelength-compatible light cut. A filter 112 and a short wavelength band light cut filter 114 are provided. The automatic focus detection module 100 is also provided with a flat plate 110, which is not shown in FIG. 2 for convenience. The auxiliary wavelength-compatible light cut filter 112 and the short wavelength band light cut filter 114 are separate and independent components having different spectral characteristics. In FIG. 2, these filters are shown as a single filter for convenience. The flat plate 110, the auxiliary wavelength compatible light cut filter 112, and the short wavelength band light cut filter 114 will be described in detail later.

  The condenser lens 101 is a condensing lens disposed behind the planned focal plane (primary imaging plane) on which the subject image (primary image) by the photographing lens 51 is formed.

  The separator mask 102 and the separator lens 103 divide the subject luminous flux collected from the condenser lens 101 into pupils. The separator mask 102 is disposed on the incident side of the separator lens 103 and has a pair of transmission holes 102 </ b> V and 102 </ b> H that transmit the subject light flux. The transmission hole 102V is an opening pair including two openings arranged in the vertical direction, and the transmission hole 102H is an opening pair including two openings arranged in the horizontal direction. Further, a transmission hole 102H 'for transmitting the subject light beam is also disposed below the pair of openings. The transmission hole 102 </ b> H ′ is an opening pair including two openings arranged in the horizontal direction. The separator lens 103 is an element in which three pairs of lenses formed at positions corresponding to the respective transmission holes are integrally formed, and re-images the subject image on the planned focal plane on the focus detection element 104.

  The focus detection element 104 includes three pairs of line sensors that receive and integrate each of three pairs of subject images (secondary images) obtained by dividing the pupil. Of the three pairs of line sensors, a pair is a pair of horizontal line sensors 104H for detecting vertical lines arranged in the horizontal direction, and the subject luminous flux is transmitted through the transmission hole 102H and the separator lens 103 corresponding to the transmission hole 102H. Receive light. The other pair is a pair of vertical line sensors 104V for detecting horizontal lines arranged in the vertical direction, and receives the subject light flux through the transmission hole 102V and the separator lens 103 corresponding to the transmission hole 102V. The remaining pair is a pair of horizontal line sensors 104H ′ for detecting vertical lines arranged in the horizontal direction, and receives the subject light flux through the transmission hole 102H ′ and the separator lens 103 corresponding to the transmission hole 102H ′. .

  The body CPU 20 calculates the phase difference of the subject image re-imaged on the line sensor based on the output of at least one of the pair of horizontal line sensors 104H and the pair of vertical line sensors 104V or the output of the pair of horizontal line sensors 104H ′. Detect and obtain the focal position (calculate defocus amount). If the defocus amount obtained by this calculation is smaller than the predetermined focus width (the distance between the subject images on the paired line sensors is substantially the predetermined length, the body CPU 20 can be regarded as having no phase difference. State), and determined to be in focus. If the defocus amount obtained by the calculation is outside the range of the predetermined focus width, the body CPU 20 (the interval between the subject images on the paired line sensors is shorter or longer than the predetermined length, and the phase difference In this state, the front pin or the rear pin is determined, and the focus of the photographic lens 51 is adjusted according to the defocus amount.

  FIG. 3 is a diagram showing the arrangement of each element constituting the automatic focus detection module 100. In FIG. 3, the arrangement of each element in the camera body 10 is reproduced without expanding the optical path as shown in FIG. In FIG. 3, the separator mask 102, the separator lens 103, and the focus detection element 104 are simply shown for convenience. As shown in FIG. 3, a flat plate 110, an auxiliary wavelength compatible light cut filter 112, and a short wavelength band light cut filter 114 are disposed in the optical path between the condenser lens 101 and the separator mask 103. The auxiliary wavelength-corresponding light cut filter 112 is disposed in front of each opening of the transmission holes 102 </ b> V and 102 </ b> H, and transmits short wavelength light and reflects or absorbs auxiliary wavelength light. Further, the short wavelength band light cut filter 114 is disposed in front of each opening of the transmission hole 102H ′, and transmits the auxiliary wavelength corresponding light and reflects or absorbs the short wavelength band light.

  The flat plate 110 is a wedge-shaped flat plate, and has a half mirror surface 110a (surface on the condenser lens 101 side) and a mirror surface 110b (surface opposite to the half mirror surface 110a) that are non-parallel to each other. The subject luminous flux emitted from the condenser lens 101 is incident on the half mirror surface 110a. The half mirror surface 110a transmits light corresponding to the wavelength of auxiliary projection by the auxiliary projection lamp 30 (auxiliary wavelength-corresponding light) out of the incident subject luminous flux, and light in a shorter wavelength range than the auxiliary wavelength-corresponding light. At least a part of the light (short wavelength region light) is reflected. The short-wavelength light reflected by the half mirror surface 110a passes through the auxiliary wavelength-corresponding light cut filter 112, and is divided by the separator mask 102 (transmission holes 102V and 102H) and the separator lens 103, and the focus detection element. Re-imaging is performed on the 104 line sensors 104V and 104H.

  As this short wavelength region light, visible region light is mainly assumed. However, when the auxiliary wavelength-corresponding light is light in the red wavelength region, the short wavelength region light is strictly light in a region lacking the vicinity of the upper end of the visible region. The visible region is, for example, 400 nm to 700 nm, but this numerical range is defined by design, and may vary slightly depending on the design concept.

  Here, FIG. 4 shows the spectral reflectance characteristics of the half mirror surface 110 a of the flat plate 110. In the present embodiment, the wavelength of auxiliary projection by the auxiliary projection lamp 30 is 720 nm ± 20 nm. Therefore, the spectral reflectance characteristic of the half mirror surface 110a reflects most of the visible region light while transmitting the auxiliary wavelength-corresponding light. Therefore, as shown in FIG. 4, on the short wavelength side around 670 nm. It is designed such that the reflectance is high and the reflectance is low (that is, the transmittance is high) on the long wavelength side. Note that the spectral reflectance characteristic of the half mirror surface 110 a substantially matches the spectral characteristic of the image sensor 15.

  The auxiliary wavelength corresponding light transmitted through the half mirror surface 110a travels through the flat plate 110 and is incident on the mirror surface 110b. The mirror surface 110b is provided with a metal coat (for example, an aluminum coat) and has a spectral characteristic that reflects auxiliary wavelength-corresponding light (720 nm ± 20 nm light). As shown in FIG. 3, the mirror surface 110b is not arranged in parallel with the half mirror surface 110a in the longitudinal section direction (direction parallel to the paper surface of FIG. 3), and has a predetermined angle with respect to the half mirror surface 110a. It is arranged at an angle. Thereby, in the longitudinal section direction (direction parallel to the paper surface of FIG. 3), the reflection angle of the auxiliary wavelength-corresponding light on the mirror surface 110b becomes an obtuse angle than the reflection angle of the short wavelength region light on the half mirror surface 110a. Therefore, the auxiliary wavelength-corresponding light reflected by the mirror surface 110b is emitted from the half mirror surface 110a to the outside of the flat plate 110, and then away from the optical path of the short wavelength light reflected by the half mirror surface 110a. The light passes through the short-wavelength light cut filter 114, is divided by the separator mask 102 (transmission hole 102H ′) and the separator lens 103, and re-imaged on the line sensor 104H ′ of the focus detection element 104.

  In the present embodiment, since the transmission holes 102V and 102H and the transmission hole 102H ′ are arranged close to each other, the short wavelength light reflected by the half mirror surface 110a passes through the transmission hole 102H ′. Then, the light may be received by the line sensor 104H ′ of the focus detection element 104 and become noise. Further, the auxiliary wavelength-corresponding light reflected by the mirror surface 110b may be received by the line sensors 104V and 104H of the focus detection element 104 through the transmission holes 102V and 102H, resulting in noise. Therefore, the auxiliary wavelength-corresponding light cut filter 112 is disposed in front of each opening of the transmission holes 102V and 102H, so that the auxiliary wavelength-corresponding light reflected by the mirror surface 110b cannot pass through the transmission holes 102V and 102H. At the same time, the short wavelength band light cut filter 114 is arranged in front of each opening of the transmission hole 102H ′, so that the short wavelength band light reflected by the half mirror surface 110a cannot be transmitted through the transmission hole 102H ′. . Thereby, the trouble which unnecessary light is received by each line sensor and becomes noise is avoided.

[Interlocking Process of Auxiliary Floodlight 30 and Focus Detection Element 104]
FIG. 5 shows a flowchart of the interlocking process between the auxiliary floodlight 30 and the focus detection element 104, which is executed by the body CPU 20. This interlocking process is repeatedly executed, for example, during the period when the power of the photographing apparatus 1 is turned on.

[S1 in FIG. 5 (auxiliary projection determination process)]
The body CPU 20 determines whether or not the auxiliary floodlight 30 is caused to emit light. When the body CPU 20 causes the auxiliary floodlight 30 to emit light (S1: YES), the body CPU 20 advances the processing to S2 (focus detection processing using a subject light beam made of auxiliary wavelength-corresponding light). When the auxiliary light projection lamp 30 is not emitting light (S1: NO), the body CPU 20 advances the process to S3 (focus detection process using a subject light beam made of short wavelength region light).

[S2 in FIG. 5 (Focus Detection Processing Using Subject Light Beam Consisting of Auxiliary Wavelength Compatible Light)]
As described above, the auxiliary floodlight 30 uses light in the red or near-infrared wavelength region, that is, auxiliary wavelength-compatible light so that the subject (person) does not feel glare. Further, since the auxiliary floodlight 30 emits light at low brightness, the subject luminous flux contains almost no short wavelength region light. Therefore, the subject luminous flux mainly passes through the half mirror surface 110a, is reflected by the mirror surface 110b, and passes through the half mirror surface 110a again. The subject luminous flux that has been transmitted again through the half mirror surface 110a is transmitted through the short wavelength band light cut filter 114 and is divided by the separator mask 102 (transmission hole 102H ′) and the separator lens 103, and the line sensor of the focus detection element 104. Reimaged on 104H ′. The body CPU 20 performs focus detection based on the outputs of the pair of line sensors 104H ′. As a result, the focus of the subject is detected in a state where the effect of insufficient luminance improvement by the auxiliary light projection is obtained. In this process, the outputs of the line sensors 104V and 104H whose luminance is insufficient may be always discarded.

[S3 in FIG. 5 (Focus Detection Processing Using Subject Light Beam Consisting of Short Wavelength Range Light)]
Sunlight, incandescent light, and the like include not only the visible region but also a long wavelength region such as the near infrared region, while fluorescent light or the like does not include a long wavelength region such as the near infrared region. Therefore, when the same subject is illuminated with the sun or an incandescent bulb, and when illuminated with a fluorescent lamp, the focal point differs due to chromatic aberration (mainly chromatic aberration in a long wavelength region such as the near infrared region) of the photographing lens 51. Detection is performed. Therefore, when the auxiliary floodlight 30 does not emit light, the body CPU 20 discards the output of the line sensor 104H ′ of the focus detection element 104 (or turns off the line sensor 104H ′), and based on the output of the line sensors 104V and 104H. Perform focus detection. That is, by performing focus detection based on information that does not include the subject light beam on the longer wavelength side than the short wavelength region light, the influence of chromatic aberration on the longer wavelength side than the short wavelength region light by the photographing lens 51 is eliminated. . For this reason, focus detection errors due to different light sources (sun, incandescent bulb, fluorescent lamp, etc.) for illuminating the subject are substantially eliminated.

  As shown in FIG. 3, the auxiliary wavelength-corresponding light reflected by the mirror surface 110b has a longer optical path than the short wavelength light reflected by the half mirror surface 110a. For this reason, the base line length at the time of focusing and the imaging position in the optical axis direction are different between the auxiliary wavelength corresponding light and the short wavelength region light. In this embodiment, in order to avoid deterioration in focus detection accuracy due to different base line lengths, in this embodiment, the base line lengths at the time of focusing are associated with the corresponding wavelengths (more precisely, the corresponding line sensors) in the gamera body 10. Are stored in advance in a memory (not shown), and an appropriate base line length is switched according to a line sensor used for focus detection. Further, the half mirror surface 110a and the mirror surface 110b are arranged on the planned focal plane side with respect to the separator lens 103, and the imaging magnification of the separator lens 103 is generally a reduction system (usually about 0.1 to 0.3 times). Thus, the difference in the imaging position in the optical axis direction becomes smaller in proportion to the square of the reduction magnification (about 1/10 to 1/100). That is, since the difference in the imaging position in the optical axis direction is a slight difference, it is not a substantial problem (substantial difference).

  According to the present embodiment, the effect of improving the brightness shortage when the auxiliary projection lamp 30 is irradiated is obtained, and the increase in focus detection error due to aberrations such as near infrared is suppressed when the auxiliary projection lamp 30 is not irradiated. To achieve this, there is no need to move optical elements such as optical filters and optical lenses with respect to the optical path. Therefore, there is no possibility that the focus detection accuracy is deteriorated depending on the mounting error (positional accuracy) of the optical element configured to be movable.

  The above is the description of the exemplary embodiments of the present invention. Embodiments of the present invention are not limited to those described above, and various modifications are possible within the scope of the technical idea of the present invention. For example, the embodiment of the present application also includes an embodiment that is exemplarily specified in the specification or a combination of obvious embodiments and the like as appropriate.

DESCRIPTION OF SYMBOLS 1 Camera 10 Camera body 11 Main mirror 12 Penta prism 13 Fine loupe 14 Sub mirror 15 Image sensor 20 Body CPU
30 Auxiliary projection lamp 50 Interchangeable lens 51 Shooting lens 100 Automatic focus detection module 101 Condenser lens 102 Separator masks 102V, 102H, 102H ′ Transmission hole 103 Separator lens 104 Focus detection element 104V Vertical line sensors 104H, 104H ′ Horizontal line sensor 110 Flat plate 110a Half mirror surface 110b Mirror surface 112 Auxiliary wavelength cut light filter 114 Short wavelength range light cut filter

Claims (7)

An automatic focus detection device for a photographing device capable of projecting auxiliary light toward a subject, wherein the subject luminous flux through the photographing lens of the photographing device is divided to detect at least a pair of subject images differently By forming an image on the focus detection sensor in the area, the phase difference between at least a pair of images is detected, and the focal position of the subject is detected based on the detected phase difference.
In the optical path between the photographic lens and the focus detection sensor,
Separation of the subject luminous flux to be separated into light corresponding to the wavelength of the auxiliary light (auxiliary wavelength compatible light) and light in at least a part of the wavelength range other than the auxiliary wavelength compatible light (non-auxiliary wavelength compatible light) Means,
First deflecting means for deflecting the non-auxiliary wavelength compatible light separated by the separating means toward the first sensor on the focus detection sensor;
Second deflecting means for deflecting light corresponding to the auxiliary wavelength separated by the separating means toward a second sensor different from the first sensor on the focus detection sensor;
Is placed,
When the auxiliary light is not projected by the photographing device, the first sensor detects a phase difference of the image made of the non-auxiliary wavelength compatible light,
The automatic focus detection apparatus, wherein when the auxiliary light is projected by the photographing apparatus, the second sensor detects a phase difference of an image composed of the auxiliary wavelength light. The separating means and the first deflecting means are formed on the same surface,
The same surface on which the separating means and the first deflecting means are formed is:
2. The automatic mirror according to claim 1, wherein the automatic light beam is a half mirror surface that transmits the auxiliary wavelength-corresponding light in the subject light flux and reflects the non-auxiliary wavelength-corresponding light toward the first sensor. Focus detection device. The second deflecting means is
3. The automatic focus detection device according to claim 2, wherein the automatic focus detection device is a mirror surface disposed so as to reflect the auxiliary wavelength-corresponding light transmitted through the half mirror surface toward the second sensor. It has a wedge-shaped flat plate,
The flat plate
The first surface on the photographing lens side is the half mirror surface,
4. The automatic focus detection apparatus according to claim 3, wherein a second surface opposite to the first surface, which is disposed at a predetermined angle with respect to the first surface, is the mirror surface. A condenser lens disposed behind a planned focal plane of the photographing lens;
At least two pairs of separator lenses disposed behind the condenser lens and re-image the subject image on the planned focal plane on the focus detection sensor;
A first aperture pair corresponding to at least a pair of separator lenses disposed on an incident side of the separator lens and disposed on an optical path toward the first sensor, and disposed on an optical path toward the second sensor. A separator mask having a second opening pair corresponding to at least one pair of separator lenses;
With
The separating means, the first deflecting means and the second deflecting means are:
5. The automatic focus detection apparatus according to claim 1, wherein the automatic focus detection apparatus is disposed in an optical path between the condenser lens and the separator mask. A filter that transmits the non-auxiliary wavelength light and reflects or absorbs the auxiliary wavelength light is disposed on the first pair of apertures;
6. The automatic focus detection device according to claim 5, wherein a filter that transmits the auxiliary wavelength-corresponding light and reflects or absorbs the non-auxiliary wavelength-corresponding light is disposed on the second aperture pair. . The non-auxiliary wavelength compatible light is
The automatic focus detection apparatus according to any one of claims 1 to 6, wherein the automatic focus detection apparatus includes at least part of light in a visible region.

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