JP2014232143A - 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 and deflection means for separating a subject light flux into light corresponding to the wavelength of auxiliary light from an imaging device (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) and deflecting the non-auxiliary wavelength corresponding light to the focus detection sensor side, blocking means capable of blocking and transmitting the auxiliary wavelength corresponding light obtained through the separation by the separation and deflection means, and deflection means for deflecting the auxiliary wavelength corresponding light transmitted through the blocking means to the focus detection sensor side, wherein the blocking means transmits the auxiliary wavelength corresponding light when the auxiliary light is projected and blocks the auxiliary wavelength corresponding light when the auxiliary light is not 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 is inserted into the optical path during irradiation of the auxiliary light-projecting lamp, and near-infrared when the auxiliary light-projecting 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 part of the light other than the auxiliary wavelength compatible light Separation deflecting means for separating the separated non-auxiliary wavelength compatible light into a wavelength band light (non-auxiliary wavelength compatible light) and deflecting the separated non-auxiliary wavelength compatible light to the focus detection sensor side, and the auxiliary wavelength compatible light separated by the separation deflecting means Shielding and A shielding means capable of bulk, and deflection means are arranged for deflecting the auxiliary wavelength corresponding light passing through the shielding means to the focus detection sensor side. The shielding means allows the auxiliary wavelength-corresponding light to pass when the auxiliary light is projected by the photographing apparatus, and shields the auxiliary wavelength-corresponding light when the auxiliary light is not projected by the photographing apparatus.

  According to one aspect of the present invention, there is no need to move an optical element such as an optical filter or an optical lens with respect to the optical path when switching transmission / shielding of light corresponding to the auxiliary wavelength to the focus detection sensor. 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 separation deflecting unit is, for example, a mirror member that transmits auxiliary wavelength-corresponding light in the subject light flux and reflects non-auxiliary wavelength-corresponding light toward the focus detection sensor.

  The deflecting unit is, for example, a mirror member that reflects the auxiliary wavelength compatible light that has passed through the shielding unit toward the focus detection sensor.

  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. It is good also as a structure provided with at least a pair of separator lens and the separator mask which is arrange | positioned at the entrance side of a separator lens and has an opening pair corresponding to at least a pair of separator lens. In this configuration, the separation deflecting unit, the shielding unit, and the deflecting unit are disposed, for example, in the optical path between the condenser lens and the separator mask.

  The automatic focus detection apparatus also includes an image of the exit pupil of the photographing lens by the non-auxiliary wavelength-corresponding light reflected by the separation deflecting unit and an image of the exit pupil of the photographing lens by the assisting wavelength-corresponding light reflected by the deflecting unit. The deflecting unit may be inclined with respect to the separation deflecting unit by a predetermined first angle so as to be incident on substantially the same position on the separator mask.

  In addition, the automatic focus detection device is configured so that the secondary image by the non-auxiliary wavelength-corresponding light reflected by the separating deflection unit and the secondary image by the auxiliary wavelength-corresponding light reflected by the deflection unit are substantially the same on the focus detection sensor A configuration may be adopted in which the deflecting unit is inclined with respect to the separation deflecting unit by a predetermined second angle so that the image is re-imaged at the position.

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

  The shielding means is, for example, a liquid crystal shutter.

  According to the automatic focus detection apparatus according to an aspect of the present invention, there is no need to move an optical element such as an optical filter or an optical lens with respect to the optical path in order to switch transmission / shielding of auxiliary wavelength compatible light to the focus detection sensor. Absent. 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 separation deflection | deviation mirror with which the automatic focus detection module of this embodiment was equipped. It is a figure which shows the flowchart of the interlocking | linkage process of an auxiliary light projection lamp and a liquid-crystal shutter. It is a figure which shows arrangement | positioning of each element which comprises the automatic focus detection module of another embodiment (optical path non-development).

  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 automatic focus detection module 100 is an automatic focus detection module that employs a phase difference method, and includes a condenser lens 101, a separator mask 102, a separator lens 103, and a focus detection element 104, as shown in FIG. The automatic focus detection module 100 is also provided with a separation deflecting mirror 110, a liquid crystal shutter 120, and a deflecting mirror 130, which are not shown in FIG. 2 for convenience. The separation deflection mirror 110, the liquid crystal shutter 120, and the deflection mirror 130 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. The separator lens 103 is an element in which two pairs of lenses formed at positions corresponding to the respective transmission holes are integrally formed, and re-forms the subject image on the planned focal plane on the focus detection element 104.

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

  The body CPU 20 detects 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 to determine the focal position (defocused). Calculate the 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.

  FIGS. 3A and 3B are diagrams showing the arrangement of the elements constituting the automatic focus detection module 100. FIG. 3A and 3B, the arrangement of each element in the camera body 10 is reproduced without developing 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 FIGS. 3A and 3B, the separation deflecting mirror 110, the liquid crystal shutter 120, and the deflecting mirror 130 are disposed in the optical path between the condenser lens 101 and the separator mask 103.

  The subject light beam emitted from the condenser lens 101 enters the separation deflection mirror 110. The separation deflecting mirror 110 transmits light corresponding to the wavelength of auxiliary projection by the auxiliary projection lamp 30 (auxiliary wavelength-corresponding light) in the incident subject luminous flux, and has 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 band light reflected by the separation deflecting mirror 110 is divided by the separator mask 102 and the separator lens 103 and re-imaged on the line sensors 104V and 104H of the focus detection element 104 (FIG. 3 ( a) and (b)).

  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 separation deflection mirror 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 separation deflecting mirror 110 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 characteristics of the separation deflecting mirror 110 substantially coincide with the spectral characteristics of the image sensor 15.

  The auxiliary wavelength-corresponding light transmitted through the separation deflecting mirror 110 is incident on the liquid crystal shutter 120. The liquid crystal shutter 120 shields or transmits the auxiliary wavelength compatible light in accordance with the liquid crystal orientation control by the body CPU 20. The automatic focus detection module 100 may include a mechanical shutter instead of the liquid crystal shutter 120 (means for selectively shielding / transmitting light corresponding to the auxiliary wavelength). In the case of the liquid crystal shutter 120, it is advantageous for miniaturization design and ensuring of reliability of the automatic focus detection module 100 by eliminating the need for mechanical driving means. On the other hand, in the case of a mechanical shutter, there is an advantage that there is no loss of light quantity when transmitting auxiliary wavelength compatible light.

  The auxiliary wavelength compatible light transmitted through the liquid crystal shutter 120 is incident on the deflection mirror 130. The deflection mirror 130 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 FIGS. 3A and 3B, the deflection mirror 130 is not arranged in parallel with the separation deflection mirror 110 in the longitudinal section direction (direction parallel to the paper surface of FIG. 3). 110 is disposed at a predetermined first angle with respect to 110. Thereby, in the longitudinal section direction (direction parallel to the paper surface of FIG. 3), the reflection angle of the auxiliary wavelength-corresponding light at the deflection mirror 130 becomes an acute angle than the reflection angle of the short wavelength band light at the separation deflection mirror 110. Therefore, the auxiliary wavelength-corresponding light reflected by the deflecting mirror 130 passes through the liquid crystal shutter 120 and the separating deflecting mirror 110 in order while approaching the optical path of the short wavelength band light reflected by the separating deflecting mirror 110, and the separator mask. The light is incident on the same position as the short wavelength light on 102 (see FIG. 3B). As described above, in this embodiment, the exit pupil position of the photographic lens 51 corresponding to the opening of the separator mask 102 can be substantially matched.

  Here, the incident positions of the short wavelength region light and the auxiliary wavelength corresponding light on each of the line sensors 104V and 104H of the focus detection element 104 are at least in the longitudinal section direction (the paper surface of FIG. 3). In directions parallel to each other). Therefore, each line sensor 104V and 104H is independently provided with a sensor array corresponding to these two types of light so that both the short wavelength band light and the auxiliary wavelength compatible light can be detected. In another embodiment, when the focus detection element 104 is, for example, an area sensor, light (light with a short wavelength band or auxiliary light) is received by appropriately shifting one or more line sensor rows that are effective in detection. It is possible to output an appropriate signal corresponding to the wavelength-corresponding light.

[Interlocking process of auxiliary floodlight 30 and liquid crystal shutter 120]
FIG. 5 shows a flowchart of the interlocking process between the auxiliary floodlight 30 and the liquid crystal shutter 120 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 auxiliary floodlight 30 is caused to emit light (S1: YES), the body CPU 20 advances the process to S2 (orientation control to a light transmission state). If the auxiliary floodlight 30 is not emitting light (S1: NO), the body CPU 20 advances the processing to S3 (orientation control to a light shielding state).

[S2 in FIG. 5 (orientation control to light transmission state)]
As described above, the auxiliary floodlight 30 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 the light in the near-infrared region or the like is cut, it becomes difficult to detect the focus itself due to insufficient luminance. Therefore, when the auxiliary floodlight 30 emits light, the body CPU 20 controls the orientation of the liquid crystal shutter 120 to the light transmission state. As a result, the auxiliary wavelength-corresponding light transmitted through the separation deflecting mirror 110 passes through the liquid crystal shutter 120 and is reflected by the deflecting mirror 130 as shown in FIG. The light passes through the mirror 110. The auxiliary wavelength-corresponding light transmitted again through the separation deflecting mirror 110 is re-imaged on the line sensors 104 </ b> V and 104 </ b> H of the focus detection element 104 through the separator mask 102 and the separator lens 103.

  On the line sensors 104V and 104H, both the short wavelength light reflected by the separation deflecting mirror 110 and the auxiliary wavelength corresponding light reflected by the deflecting mirror 130 are re-imaged. However, since the auxiliary floodlight 30 emits light at low brightness, the amount of light in the short wavelength region is small. Therefore, the auxiliary wavelength-corresponding light is dominant in the proportion of light received by the line sensors 104V and 104H. Therefore, the body CPU 20 performs focus detection based on the output of the sensor array corresponding to the auxiliary wavelength compatible light. 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.

[S3 in FIG. 5 (orientation control to light shielding state)]
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, the body CPU 20 controls the orientation of the liquid crystal shutter 120 to the light shielding state when the auxiliary floodlight 30 does not emit light. Thereby, the auxiliary wavelength compatible light transmitted through the separation deflecting mirror 110 is blocked by the liquid crystal shutter 120. Accordingly, as shown in FIG. 3A, only the short wavelength light reflected by the separation deflecting mirror 110 is re-imaged on the line sensors 104 </ b> V and 104 </ b> H of the focus detection element 104. In this case, focus detection is performed based on information that does not include the subject luminous flux on the longer wavelength side than the short wavelength band light. That is, since the focus detection is performed in a state where the influence of chromatic aberration on the longer wavelength side than the short wavelength range light by the photographing lens 51 is eliminated, the light source (sun, incandescent bulb, fluorescent lamp, etc.) for illuminating the subject is different. The focus detection error due to this is substantially eliminated.

  The auxiliary wavelength-corresponding light reflected by the deflection mirror 130 has a longer optical path than the short-wavelength range light reflected by the separation deflection mirror 110, as shown in FIG. 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 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 each focus are stored in advance in a memory (not shown) in the gamer body 10, and an appropriate base line length is obtained. Is switched in conjunction with the auxiliary floodlight 30 (in other words, the wavelength of light received by each of the line sensors 104V and 104H of the focus detection element 104). Further, the separation deflecting mirror 110 and the deflecting mirror 130 are disposed closer to the planned focal plane than 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, there is no need to move an optical element such as an optical filter or an optical lens with respect to the optical path when switching transmission / shielding of auxiliary wavelength compatible light to the focus detection element 104. 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.

  FIGS. 6A and 6B show the arrangement of elements constituting an automatic focus detection module 100 of another embodiment. 6 (a) and 6 (b), as in FIGS. 3 (a) and 3 (b), the arrangement of each element in the camera body 10 is reproduced without expanding the optical path as in FIG. . In another embodiment, as shown in FIGS. 6A and 6B, the deflection mirror 130 is arranged in parallel with the separation deflection mirror 110 in the longitudinal section direction (direction parallel to the paper surface of FIG. 6). Instead, it is arranged at a predetermined second angle with respect to the separation deflecting mirror 110. The auto focus detection module 100 of another embodiment is illustrated in FIG. 3 except that the tilt angle of the deflection mirror 130 with respect to the separation deflecting mirror 110 is different from the auto focus detection module 100 illustrated in FIG. It has substantially the same configuration as the automatic focus detection module 100.

  By disposing the deflection mirror 130 at a predetermined second angle with respect to the separation deflection mirror 110, the central axis of the short wavelength band light reflected by the separation deflection mirror 110 and the reflection mirror 130 are reflected. The central axis of the auxiliary wavelength-corresponding light substantially coincides (more specifically, the central axis of any light substantially coincides with the optical axis of the separator lens 103). Therefore, the incident positions of the short wavelength region light and the auxiliary wavelength compatible light on the line sensors 104V and 104H of the focus detection element 104 substantially coincide. Therefore, it is not necessary to provide each line sensor 104V, 104H with a sensor array for detecting each of the short wavelength band light and the auxiliary wavelength compatible light. Further, when the focus detection element 104 is, for example, an area sensor, it is not necessary to appropriately shift one or a plurality of line sensor rows effective in detection. In another embodiment, the exit pupil position of the photographic lens 51 corresponding to the opening of the separator mask 102 is shifted in the longitudinal sectional direction, but the focus detection range by the auxiliary wavelength-corresponding light is narrower than the focus detection range in the short wavelength region light. By setting, vignetting of the light beam necessary for focus detection can be avoided.

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 and 102H Transmission hole 103 Separator lens 104 Focus detection element 104V Vertical line sensor 104H Horizontal line sensor 110 Separation deflecting mirror 120 Liquid crystal shutter 130 Deflection mirror

Claims (8)

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 of the region, 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,
Separating the subject luminous flux 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); And separation deflecting means for deflecting the separated non-auxiliary wavelength compatible light to the focus detection sensor side,
Shielding means capable of shielding and allowing the auxiliary wavelength-corresponding light separated by the separation deflection means;
Deflection means for deflecting auxiliary wavelength-corresponding light that has passed through the shielding means toward the focus detection sensor;
Is placed,
The shielding means is
Passing the auxiliary wavelength-corresponding light when the auxiliary light is projected by the photographing device;
An automatic focus detection apparatus, wherein the auxiliary wavelength-corresponding light is shielded when the auxiliary light is not projected by the photographing apparatus. The separation deflecting means includes
2. The automatic focus detection device according to claim 1, wherein the automatic focus detection device is a mirror member that transmits the light corresponding to the auxiliary wavelength of the subject light flux and reflects the light corresponding to the non-auxiliary wavelength toward the focus detection sensor. . The deflection means includes
3. The automatic focus detection device according to claim 2, wherein the automatic focus detection device is a mirror member that reflects the auxiliary wavelength corresponding light that has passed through the shielding means toward the focus detection sensor. A condenser lens disposed behind a planned focal plane of the photographing lens;
At least a pair 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 separator mask disposed on the incident side of the separator lens and having an opening pair corresponding to the at least one pair of separator lenses;
With
The separating and deflecting means, the shielding means and the deflecting means are:
4. 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. 5. An image of the exit pupil of the photographing lens by the non-auxiliary wavelength corresponding light reflected by the separation deflecting unit and an image of the exit pupil of the photographing lens by the auxiliary wavelength corresponding light reflected by the deflecting unit are on the separator mask. 5. The method according to claim 4, wherein the deflecting unit is inclined with respect to the separation deflecting unit by a predetermined first angle so as to be incident at substantially the same position. Automatic focus detection device. The secondary image by the non-auxiliary wavelength-corresponding light reflected by the separation deflecting unit and the secondary image by the auxiliary wavelength-corresponding light reflected by the deflecting unit are re-imaged at substantially the same position on the focus detection sensor. 5. The automatic focus detection apparatus according to claim 4, wherein the deflecting unit is inclined with respect to the separation deflecting unit by a predetermined second angle. 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. The shielding means includes
The automatic focus detection apparatus according to claim 1, wherein the automatic focus detection apparatus is a liquid crystal shutter.

Images