JP2019128548A - Focus detector and optical apparatus equipped with focus detector - Google Patents

Abstract

To provide a focus detector with which it is possible to detect a focus with high accuracy even when ghost light enters a focus detection sensor, and an optical apparatus equipped with the focus detector.SOLUTION: In order to detect the in-focus state of an external focus lens 101 by a phase difference detection system, a focus detector 207 includes a focus detection sensor 400 in which an image forming region 401 within an image field range and a ghost detection region 402 in its periphery are provided, and identifies a region of the ghost detection region 402 where ghost light occurs when a prescribed light source is incident on the focus lens 101. When the occurrence of ghost light is detected by output from the identified region at the time of focus adjustment of the focus lens 101, detection is made as to whether or not ghost light has occurred at a position in the image-forming region 401 that affects the detection of the in-focus state and, when so detected, detection is made of an in-focus state after correcting the output of the focus detection sensor 400.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a focus detection apparatus and an optical apparatus including the focus detection apparatus, and more particularly to a focus detection apparatus capable of automatic focus detection and an optical apparatus including the focus detection apparatus.

  In single-lens reflex cameras, focus detection using a phase difference detection method that detects the focus state (defocus amount) of a shooting optical system from the phase difference of a plurality of image signals formed by light passing through the shooting optical system in an interchangeable lens. Devices are often mounted. A focus detection sensor and a secondary imaging optical system dedicated to phase difference detection for forming an object image on the focus detection sensor are provided inside the focus detection apparatus using such a phase difference detection method. For this reason, unnecessary light (hereinafter referred to as “ghost light”) generated by reflection or the like by a structure included in the focus detection apparatus enters the focus detection sensor via the secondary imaging optical system. There is a problem that the detection accuracy is lowered.

  For example, in Patent Document 1, when the position of the photographing light source is detected from the subject image obtained by the focus detection device, a ghost corresponding to the position of the detected photographing light source and the position of the photographing light source stored in advance in the storage means A technique for correcting ghost light based on light information is disclosed. Further, in Patent Document 2, the occurrence of ghost light is predicted from the luminance information in the subject image obtained by the imaging device, and the ghost light is corrected with the information generated based on the predicted generation mode of the ghost light. Technology is disclosed.

JP, 2006-184321, A JP, 2006-129084, A

  However, in the prior art disclosed in Patent Documents 1 and 2 described above, a large amount of data is necessary to predict the position and intensity of ghost light generated according to the position of the photographing light source and the luminance information in the subject image. is there. That is, data must be prepared for each parameter, such as the position of the photographing light source, the type of photographing lens, and the subject distance, which are factors that change the position and intensity of ghost light. In addition, since a high brightness subject does not always generate ghost light, it is necessary to accurately predict the generation of ghost light for all high brightness bodies in the subject image. Therefore, much time is spent on analysis and processing of the subject image. Furthermore, since ghost light may exist outside the area where the subject image of the imaging device or focus detection sensor is formed, in such a case, the ghost light is used in the prior art disclosed in the above-mentioned patent documents 1 and 2 Is difficult to correct.

  In view of such circumstances, it is an object of the present invention to provide a focus detection apparatus capable of accurately detecting focus even when ghost light is incident on a focus detection sensor, and an optical apparatus provided with the focus detection apparatus.

  A focus detection apparatus according to claim 1 of the present invention is a focus detection apparatus having a sensor for detecting a focus state of an external focus lens by a phase difference detection method, and the sensor includes a range of an image field. Ghost light in the second sensor area when a predetermined light source is incident on the focus lens. Identification means for identifying a region where the ghost light has occurred, and first detection means for detecting whether or not the ghost light is generated based on an output from the identified region during focus adjustment of the focus lens; As a result of detection by the first detection means, when the ghost light is generated, second detection means for detecting whether other ghost light is generated in the first sensor region; and the second As a result of the detection by the detection means, when the other ghost light is generated and the generation position of the other ghost light affects the detection of the in-focus state, after correcting the output of the sensor, And a third detection unit configured to detect an in-focus state according to the phase difference detection method.

  A focus detection apparatus according to a tenth aspect of the present invention is a focus detection apparatus having a sensor for detecting the in-focus state of an external focus lens by a phase difference detection method. A first sensor area in the range of a pair of image fields and a second sensor area around each of the first sensor areas are provided, and are parallel to the correlation direction according to the focus detection range. Ghost light is generated in the second sensor area when a predetermined light source is incident on the focus lens, and first setting means for setting a focus detection line in each of the first sensor areas in a specific direction. First identifying means for identifying a region, and a first region for identifying another region where ghost light is predicted to be generated in the first sensor region, based on a positional relationship between the first sensor region and the identified region. In the region identified by the first identifying means, a second setting means for setting a ghost detection line in a direction parallel to each of the correlation directions, and during focus adjustment of the focus lens, When there is a first focus detection line in a position overlapping with the region identified by the second identification means in the focus detection line, the output of the first focus detection line is output from the ghost detection line Correction means for correcting based on an output of a first ghost detection line set in the same direction as the first focus detection line; and detection means for detecting an in-focus state by the phase difference detection method after the correction. It is characterized by providing.

  An optical apparatus according to a twelfth aspect of the present invention is a drive means for performing focusing by driving the focus lens in the optical axis direction according to the focus detection device, the focus lens, and the detected focusing state. It is characterized by providing.

  According to the present invention, even if ghost light is incident on the focus detection sensor, focus detection can be performed with high accuracy.

FIG. 1 is a block diagram showing a schematic configuration of an imaging apparatus as an optical apparatus provided with a focus detection device according to a first embodiment. It is a schematic sectional drawing of the focus detection apparatus in FIG. It is a top view of the visual field mask in FIG. FIG. 3 is a plan view of the porous stop in FIG. 2; It is the figure which looked at the secondary imaging lens unit in FIG. 2 from the focus detection sensor side. It is the figure which looked at the focus detection sensor from the secondary imaging lens unit side. It is a figure of a photographic subject for explaining ranging operation of an imaging device. It is a figure which shows the to-be-photographed image imaged on a focus detection sensor. It is a figure which shows the sensor output waveform of each focus detection line in FIG. It is the schematic which shows the optical path which the light ray which makes a focus detection sensor produce ghost light injects. It is a figure which shows the positional relationship of each ghost light which arises on a focus detection sensor. It is a figure which shows the sensor output waveform of the focus detection line in FIG. 11, and a ghost detection line. It is a figure which shows the generation | occurrence | production variation of ghost light when the light ray from a uniform-intensity surface light source and the light ray which produces ghost light inject into a focus detection sensor. It is the figure which expanded the ghost light which arises in the ghost detection area | region of Fig.13 (a), and its vicinity. 7 is a flowchart showing the procedure of focus adjustment processing in the first embodiment. It is a figure for demonstrating the resetting method of the focus detection line of step S7 of FIG. 7 is a flowchart showing the procedure of focus adjustment processing in the second embodiment. FIG. 16 is a flowchart showing the procedure of focus adjustment processing in Embodiment 3. FIG. It is the figure which expanded the ghost detection area vicinity of FIG. 8 which linear ghost light has produced. It is the figure which showed the linear ghost light vicinity of FIG. 19 for every pixel. FIG. 18 is a flowchart illustrating a procedure of correction processing at the time of focus detection operation in Embodiment 4. FIG. In Example 5, it is a figure which shows the positional relationship of ghost light when the light ray which produces ghost light injects into a focus detection sensor. FIG. 18 is a diagram showing a sensor output waveform of a focus detection line and a sensor output waveform of a ghost detection line in Example 5 when ghost light is generated in the focus detection sensor when the subject is a white cross hair. FIG. 18 is a flowchart showing the procedure of focus adjustment processing in Embodiment 5. FIG. It is a figure for demonstrating the correction method of the output of the image formation area | region in step S504 of FIG. FIG. 17 is a diagram showing accumulation time control of the sensor output waveform of the focus detection line and the sensor output waveform of the ghost detection line in the fifth embodiment when ghost light is emitted to the focus detection sensor when the subject is general. is there. FIG. 18 is a diagram showing storage time control and threshold values regarding the storage time in a fifth embodiment.

  Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings, but the present invention is not limited to the following embodiments. In addition, the dimensions, shapes, relative arrangements, and the like of the components exemplified in the present embodiment should be changed as appropriate according to the configuration of the apparatus to which the present invention is applied and various conditions. It is not limited to the example.

Example 1
FIG. 1 is a block diagram showing a schematic configuration of an image pickup apparatus as an optical apparatus provided with a focus detection apparatus according to a first embodiment.

  An imaging apparatus 200 according to the first embodiment is a single-lens reflex camera, and as illustrated in FIG. 1, a photographing lens 100 is detachably attached via a lens mounting mechanism of a mount unit (not shown). An electrical contact unit 104 is provided in the mount portion. The imaging device 200 communicates with the photographing lens 100 via the electric contact unit 104, and controls the focus lens 101 in the photographing lens 100. Although only the focus lens 101 is shown in FIG. 1 as a lens in the photographing lens 100, in addition to this, a variable power lens and a fixed lens may be usually provided.

  A light beam from a subject (not shown) is guided to a main mirror 201 in the imaging apparatus 200 via a photographing optical system (including a focus lens 101) in the photographing lens 100. The main mirror 201 is disposed obliquely with respect to the photographing optical axis OA, and a first position (illustrated position) for guiding the light beam from the subject to the upper viewfinder optical system and a second position for retracting outside the photographing optical path OA. It is possible to move to the position of.

  The central portion of the main mirror 201 is a half mirror, and when the main mirror 201 is at the first position, a part of the light flux from the subject passes through the central portion of the main mirror 201 which is a half mirror. The transmitted light beam is reflected by the sub mirror 202 provided on the back side of the main mirror 201, and is guided to the focus detection device 207 on the photographing optical axis OA 'as a distance measuring light beam. The detailed configuration of the focus detection device 207 will be described later.

  On the other hand, when the main mirror 201 is at the first position, the light beam from the subject reflected by the main mirror 201 forms an image on the focus plate 203 disposed at a position optically conjugate with the image sensor 209. . The light (object image) transmitted after being imaged by the focusing plate 203 is converted into an erect image by the penta-dach prism 204. The erect image is magnified by the eyepiece 205 and can be viewed by the photographer.

  When the main mirror 201 is in the second position, the sub mirror 202 is also folded with respect to the main mirror 201 and retracted from the photographing optical axis OA. The luminous flux transmitted through the photographing optical system of the photographing lens 100 passes through a focal plane shutter 208 which is a mechanical shutter and reaches the image pickup element 209. The focal plane shutter 208 limits the amount of light incident on the imaging device 209. The imaging element 209 is configured by a photoelectric conversion element such as a CCD sensor or a CMOS sensor that photoelectrically converts an object image formed by the photographing lens 100 to generate an image and outputs an electrical signal.

  The camera control unit 210 is a controller (control unit) that controls various calculations and various operations in the imaging device 200, and is configured of a CPU, an MPU, and the like. Also, the camera control unit 210 communicates with the lens control unit 103 in the photographing lens 100 via the electrical contact unit 104. In addition, the camera control unit 210 obtains a light amount distribution (sensor output waveform) of a subject image that has been imaged and photoelectrically converted in each of a plurality of imaging regions 401B to 401D (described later) output from the focus detection sensor 400. The camera control unit 210 detects the in-focus state of the focus lens 101 by obtaining the relative positional relationship of the sensor output waveform.

  The lens control unit 103 controls the lens driving mechanism 102 that performs focusing by driving the focus lens 101 in the optical axis direction in accordance with a signal from the camera control unit 210. The lens driving mechanism 102 has a stepping motor or an ultrasonic motor as a driving source.

  Further, the camera control unit 210 is connected to an EEPROM 211 which is storage means for storing an incident area of ghost light in a focus detection sensor 400 described later of the focus detection device 207. The EEPROM 211 is a factory for parameters relating to imaging, which is adjusted in advance using parameters that require adjustment to control the imaging device 200, camera ID (identification) information for performing individual identification of the imaging device 200, and a reference lens. Adjustment values and the like are stored.

  The display unit 212 is a device that displays image data captured by the image sensor 209, items set by the photographer, and the like, and is generally configured using a color liquid crystal display element.

  Furthermore, the camera control unit 210 is connected to an operation detection unit 213 that detects an operation on the imaging device 200 by the photographer. The operation detection unit 213 detects an operation of the photographer with respect to operation members such as a release button (not shown) and a focusing operation start button. Also, settings relating to imaging are performed via the operation member, and the settings are stored in the EEPROM 211.

  On the other hand, the lens control unit 103 of the photographing lens 100 stores performance information such as a focal length and an open aperture value of the photographing lens 100 and lens ID (identification) information that is unique information for identifying the photographing lens 100. A memory (not shown) is provided. The storage device also stores information received from the camera control unit 210 through communication. The performance information and the lens ID information are transmitted from the lens control unit 103 to the camera control unit 210 through initial communication performed when the imaging lens 100 is attached to the imaging device 200, and the camera control unit 210 stores these in the EEPROM 211. Let

  The imaging device 200 may be a mirrorless camera. In this case, the main mirror 201, the focusing plate 203, the penta-dach prism 204, and the eyepiece lens 205 are removed from the imaging device 200. Further, the sub mirror 202 moves to the position shown in FIG. 1 only in the AF (automatic focus detection) mode, and retracts outside the photographing optical path OA in the other modes.

  The configuration of the focus detection apparatus 207 according to the first embodiment will be described with reference to FIGS.

  FIG. 2 is a schematic cross-sectional view of the configuration of the focus detection device 207, FIG. 3 is a plan view of the visual field mask 300, and FIG. 4 is a plan view of the aperture stop 302.

  5 is a diagram of the secondary imaging lens unit 303 as viewed from the focus detection sensor 400 side, and FIG. 6 is a diagram of the focus detection sensor 400 as viewed from the secondary imaging lens unit 303 side.

  Although not shown, at the left end of FIG. 2, there is a primary imaging plane conjugate to the imaging device 209 (the expected imaging plane of the photographing lens 100). That is, the focus detection device 207 is provided with a field mask 300, a field lens 301, a porous aperture 302, a secondary imaging lens unit 303, and a focus detection sensor 400 in order from the primary imaging plane.

  As shown in FIG. 3, the field mask 300 is a thin plate-like component, and an opening 300A is provided at the center. The shape of the aperture 300 A determines the image field to be imaged on the focus detection sensor 400.

  The field lens 301 is a convex lens and is provided in the vicinity of the field mask 300. The field lens 301 has a role of forming an image divided by the aperture stop 302 in the vicinity of the exit pupil of the photographing lens 100.

  As shown in FIG. 4, the multi-hole aperture 302 is a thin plate-like part, and openings 302A to 302D are provided at four places. The openings 302A to 302D divide the distance measurement light beam from the focus lens 101 which is incident through the field lens 301 and is outside the focus detection device 207. In the present embodiment, the openings 302A and 302B divide the distance measurement light beam in the longitudinal direction (Y direction), and 302C and 302D divide the distance measurement light beam in the lateral direction (X direction).

  As shown in FIG. 2, the secondary imaging lens unit 303 is a substantially plate-like component, and the surface facing the focus detection sensor 400 has a plurality of convex lens shapes. These convex lens shapes are respectively referred to as secondary imaging lenses 303A-D. In the first embodiment, four secondary imaging lenses are arranged to correspond to the openings 302A to 302D of the aperture stop 302.

  As shown in FIG. 5, the secondary imaging lenses 303A to 303D cause the subject image on the primary imaging plane P formed by the imaging lens 100 to be refocused on the focus detection sensor 400. The distance measurement light beam that has passed through the aperture 302A of the multi-aperture stop 302 is imaged on an imaging region 401A described later on the focus detection sensor 400 by the secondary imaging lens 303A. Similarly, the distance measurement light beams having passed through the apertures 302B to 302D of the multi-aperture stop are imaged on imaging regions 401B to 401D described later on the focus detection sensor 400 by the secondary imaging lenses 303B to 303D.

  The focus detection sensor 400 photoelectrically converts an object image formed by the secondary imaging lenses 303A to 303D for each pixel to generate an image, and outputs an electric signal. The focus detection sensor 400 includes a photoelectric conversion element such as a CCD sensor or a CMOS sensor, and the photoelectric conversion elements (pixels) are arranged in a two-dimensional array.

  As shown in FIG. 6, in the first embodiment, the pixels of the focus detection sensor 400 are arranged in a wider range than the range in which the subject image is formed. Specifically, the pixels of the focus detection sensor 400 are formed of imaging areas (first sensor areas) 401A to 401D and imaging areas A to D within a range where an object image is formed by the visual field mask 300. It is disposed in a ghost detection area (second sensor area) 402A-D in the vicinity. The imaging area 401A and the ghost detection area 402A are configured by the same sensor array. The same applies to the imaging regions 401B to 401D and the ghost detection regions 402B to 402D. The light beam that has passed through the aperture 302A of the aperture stop 302 is imaged in the range of the imaging region 401A of the focus detection sensor 400 by the secondary imaging lens 303A. Similarly, the imaging regions 401B-D correspond to the apertures 302B-D of the aperture stop 302 and the secondary imaging lenses 303B-D.

  The pixel configuration of the focus detection sensor 400 is not limited to the configuration of the first embodiment as long as the ghost detection region 402 is provided around the imaging region 401. For example, a plurality of line sensors may be combined and disposed.

  The focus detection apparatus 207 according to the first embodiment calculates the defocus amount by a focus detection method (phase difference detection method) based on known secondary imaging phase difference detection. The principle and operation of focus detection and focus adjustment will be described with reference to FIGS. 7 to 9 by taking as an example a case where focus detection is performed to shoot a subject using the imaging lens 100 and the imaging device 200. FIG.

  FIG. 7 is a view of an object for explaining the distance measuring operation of the imaging device 200, and shows the object photographed by the imaging device 200 on which the photographing lens 100 is mounted. The shooting range is a range indicated by a solid line in FIG. 8, and the focus detection range 500 is a range (so-called AF distance measurement point) selected by the photographer as a target of focus detection. Further, a range 300B indicated by a broken line indicates a field range defined by the opening 300A of the field mask 300, and an object image is formed on the focus detection sensor 400 in a range defined by the range 300B.

  FIG. 8 is a diagram showing a subject image formed on the focus detection sensor 400. The subject image in the range 300B defined by the opening 300A of the field mask 300 is divided into four images in the imaging regions 401A to D by the apertures 302A to 302D of the porous aperture 302 and the secondary imaging lenses 303A to 303D. . As a result, subject images are formed on the imaging regions 401A to 401D on the focus detection sensor 400 as shown in FIG.

  Hereinafter, the pixels at positions corresponding to the selected focus detection range 500 in the imaging regions 401A to 401D in FIG. 8 are referred to as focus detection lines 401A-1, 401B-1, 401C-1, and 401D-1, respectively. To do. The respective focus detection lines 401A-1, 401B-1, 401C-1, and 401D-1 are arranged in the correlation direction. Here, the correlation direction means a direction in which an image is divided by the apertures 302A to 302D of the porous diaphragm 302 and the secondary imaging lenses 303A to 303D. In the first embodiment, the focus detection lines 401A-1 and 401B-1 are correlated in the Y direction, and the focus detection lines 401C-1 and 401D-1 are correlated in the X direction. Each of the focus detection lines 401 A- 1, 401 B- 1, 401 C- 1, and 401 D- 1 has a plurality of pixels in the correlation orthogonal direction so as to have a width of the focus detection range 500.

  FIG. 9 is a diagram showing sensor output waveforms at each of the focus detection lines 401A-1, 401B-1, 401C-1 and 401D-1 in FIG. The horizontal axis of the graph of FIG. 9 is the position of the pixel, which is arranged in the order indicated by the arrow in FIG. The vertical axis indicates the light amount obtained by averaging the outputs of a plurality of pixels in the correlation orthogonal direction.

  The waveform shown by the solid line in FIG. 9 is a sensor output waveform in which there is no focus shift and the defocus amount is zero.

  The focus detection lines 401A-1 and 401B-1 form images of the same portion of the primary imaging plane P. Therefore, the sensor output waveforms shown by solid lines of the focus detection lines 401A-1 and 401B-1 shown in FIGS. 9A and 9B have the same shape. Similarly, sensor output waveforms shown by solid lines of the focus detection lines 401C-1 and 401D-1 shown in FIGS. 9C and 9D have the same shape.

  A waveform indicated by a broken line in FIG. 9 is a sensor output waveform in a state where the focus is shifted. The sensor output waveforms indicated by the broken lines of the focus detection lines 401A-1 and 401B-1 shown in FIGS. 9A and 9B have image shifts in opposite directions with respect to the sensor output waveforms indicated by the solid lines. Yes. Similarly, in the sensor output waveforms indicated by the broken lines of the focus detection lines 401C-1 and 401D-1 shown in FIGS. 9C and 9D, an image shift occurs in the opposite direction to the waveform indicated by the solid lines. ing.

  The two sensor output waveforms indicated by the broken lines in FIGS. 10A and 10B that are output when the focus is deviated can be matched if they are moved by a predetermined number of pixels. Similarly, the two sensor output waveforms indicated by the broken lines in FIGS. 10C and 10D that are output when the focus is deviated can be matched if they are moved by a predetermined number of pixels.

  This calculation of the predetermined number of pixels is called correlation calculation. In general, the correlation calculation treats a common area (sum set, product set) of two sensor output waveforms as a correlation amount, and calculates a predetermined number of pixels that minimizes the correlation amount. In addition, if the characteristics of the optical system of the focus detection device 207 are known, the calculated predetermined number of pixels can be converted into a movement amount of the primary imaging plane P, that is, a defocus amount. The method of correlation calculation is not limited to this example, and for example, a non-common area (corresponding to exclusive OR) of two sensor output waveforms may be used as the amount of correlation.

  The sensor output waveforms (FIGS. 9A and 9B) of the focus detection lines 401A-1 and 401B-1 have a correlation direction in the Y direction and are suitable for detecting mainly horizontal lines. In contrast, the sensor output waveforms (FIGS. 9C and 9D) of the focus detection lines 401C-1 and 401D-1 have a correlation direction of the X direction, and are suitable for detecting mainly vertical lines. Yes.

  Any of the correlation calculation results using the sensor output waveforms of FIGS. 9A and 9B and the correlation calculation results using the sensor output waveforms of FIGS. Whether to determine the defocus amount based on W depends on the waveform reliability determination. The determination of the reliability of the sensor output waveform is a known technique, and the defocus amount calculated using the sensor output waveform determined to be more reliable is adopted. In the example of FIG. 9, the X direction is the correlation direction, and the sensor output waveforms shown in FIGS. 9 (c) and 9 (d) are the correlation direction as shown in FIGS. 10 (a) and 10 (b). The sensor output waveform is determined to have high waveform reliability because the peak position and the inflection point of the waveform are clear. Therefore, the defocus amount calculated using the sensor output waveform in which the Y direction is the correlation direction is employed here.

  As described above, the example in which the correlation calculation is performed using the obtained sensor output waveform as it is has been described in the first embodiment, but the present invention is not limited to this example. For example, correlation processing may be performed after performing filter processing that makes it less susceptible to signal intensity level differences from focus detection lines in the same correlation direction, or filter processing that amplifies or attenuates specific frequency components. .

  If the defocus amount is obtained, focusing of the subject image is completed by driving the focus lens 101 of the photographing lens 100 so as to make the defocus amount zero based on the defocus amount. Note that the process of determining the reliability is not usually recognized by the photographer, and is automatically processed by the imaging device 200 and its camera control unit 210.

  The cause of the generation of ghost light and its influence in the focus detection device 207 will be described with reference to FIGS. The ghost light is a light beam which is defined by the visual field mask 300 and is incident on the focus detection sensor 400 in a light path different from that of the distance measurement light beam imaged on the focus detection sensor 400. In FIG. 2, only the main components of the focus detection device 207 are shown and the structure thereof has been described. However, in actuality, it becomes a reflection source such as a reflection mirror for bending the optical system of the focus detection device 207 and a member for holding the components. It contains many possible members.

  FIG. 10 is a schematic view showing a light path on which a light beam 403 causing ghost light to be generated in the focus detection sensor 400 is incident. As shown in FIG. 10, when the light beam 403 is reflected by the internal structure 600 of the focus detection device 207, it is transmitted to the focus detection sensor 400 via the aperture stop 302 (not shown in FIG. 10) and the secondary imaging lens unit 303. Incident. Therefore, on the focus detection sensor 400, the ghost light 403A to 403A to be shown in FIG. D is generated.

  FIG. 11 is a diagram showing the positional relationship of each of the ghost lights 403A to 403D generated on the focus detection sensor 400. As shown in FIG. In the first embodiment, among these ghost lights 403A to 403D, the ghost lights 403A, 403B, and 403C are incident on the ghost detection area 402C, and the ghost light 403D is incident on the imaging area 401A.

  In this situation, when the photographer sets the focus detection range 500 'shown in FIG. 7, focus detection lines 401A-2 and 401B-2 are provided at corresponding positions in the imaging regions 401A and 401B. In addition, ghost detection lines 402C-1 to 402C-3 are provided at positions corresponding to the ghost lights 403A to 403C.

  FIG. 12 is a diagram showing output waveforms of the focus detection lines 401A-2 and 401B-2 in FIG. Since ghost light is not incident on the focus detection line 401B-2 as shown in FIG. 11, the sensor output waveform at the focus detection line 401B-2 shown in FIG. 12B is the light intensity distribution of the object image. On the other hand, since the ghost light 403D is incident on the subject image in the focus detection line 401A-2 as shown in FIG. 11, the sensor output waveform in the focus detection line 401A-2 shown in FIG. It does not become accurate light quantity distribution of the image. Therefore, if the correlation calculation is performed based on the two sensor output waveforms of the focus detection lines 401A-2 and 401B-2, an accurate defocus amount cannot be obtained, and the subject image cannot be focused with high accuracy. .

  Therefore, in the present invention, in order to prevent erroneous distance measurement due to the ghost light 403D, ghost detection regions 402A to 402D are provided around the imaging regions 401A to D of the focus detection sensor 400. Areas other than the imaging areas 401A to 401D of the focus detection sensor 400 are areas where light rays do not enter unless ghost light is generated. Therefore, when light rays are incident on the ghost detection areas 402A to 402D, it can be determined that there is a possibility that ghost light is incident somewhere in the imaging area 401.

  Rays incident on the ghost detection areas 402A to 402D differ in incident position due to misalignment of internal structures and optical components due to component tolerances and assembly errors in the focus detection device 207. On the other hand, in the ghost detection areas 402A to 402D, there is also an area in which light reflected by the internal structure is not incident, and light rays which cause ghost light to an extent that affects distance measurement are not incident. That is, in the ghost detection areas 402A to 402D, there are areas where light rays are incident and areas where light rays are generated such that ghost light that affects ranging is generated, which differs depending on the individual of the focus detection device 207.

  In addition, light beams entering the ghost detection areas 402A to 402D have different incident positions depending on photographing conditions such as an object and composition. That is, because the irradiation condition of the internal structure changes depending on the photographing conditions, ghost light does not always appear as four images corresponding to the apertures 302A to D and the secondary imaging lenses 303A to 303D of the porous diaphragm. Their shapes are not necessarily the same. Therefore, depending on the imaging conditions, it may be difficult to predict.

  Therefore, in the present invention, parameters related to the region where ghost light is generated under a predetermined light source are stored for each individual in the focus detection device 207, and the ghost detection regions 402A to 402D are read out accordingly.

  A method of storing ghost generation areas in the ghost detection areas 402A to 402D in advance will be described with reference to FIGS. 13 and 14. This ghost generation region is stored individually for the focus detection device 207.

  FIG. 13 is a diagram showing a variation of generation of ghost lights 403A to 403C when a light ray from a predetermined light source and a light ray 403 causing ghost light enter the focus detection sensor 400. In FIG. In this embodiment, a uniform luminance surface light source (hereinafter simply referred to as “uniform luminance surface light source”) having a size enough to cover the exit pupil of the photographic lens 100 being mounted is used as the predetermined light source.

  FIG. 13 shows the state of the focus detection sensor 400 when a light beam from a uniform luminance surface light source is incident on the imaging lens 100 with respect to the imaging apparatus 200. At this time, since there is reflection by the internal structure as described above, the ray 403 is incident on a part of the ghost detection areas 402A to 402D, and at least one of the ghost lights 403A to 403 is generated.

  For example, FIG. 13A shows the case where ghost lights 403A to 403C are generated in the ghost detection area 402C. FIG. 13B shows the case where ghost light 403C is generated in the ghost detection area 402C and ghost light 403D is generated in the ghost detection area 402D. In this case, ghost light 403A is not generated as an output of focus detection sensor 400 because it does not occur on the sensor array disposed in focus detection sensor 400. Also, FIG. 13C shows the case where two linear ghost lights 403A are generated in the ghost detection area 402A.

  FIG. 14 is an enlarged view of ghost light 403C generated in the ghost detection area 402C of FIG. 13A and the vicinity thereof.

  An example of a method of storing position information of at least one of the ghost lights 403A to 403D generated in part of the ghost detection areas 402A to 402D will be described with reference to FIG.

  Hereinafter, the ghost light 403C incident on the ghost detection area 402C in FIG. 13A and the sensor pixel in the vicinity thereof will be described as an example. However, the same processing is executed for the sensor pixels in the other ghost detection regions 402A, B, and D and the imaging regions 401A, B, and D.

  The camera control unit 210 identifies, from the pixel output of the focus detection sensor 400, the sensor pixel 4031 in which the ghost light 403C generated on the ghost detection area 402C is located. Specifically, since the intensity of the imaging light is generally stronger than the intensity of the ghost light, the output value of the light beam from the uniform luminance surface light source is greater than or equal to the first predetermined value when it enters the imaging lens 100. The sensor pixel is identified as the sensor pixel 4011 in the imaging region 401C. On the other hand, if the output value is equal to or less than a second predetermined value smaller than the first predetermined value, it is identified as the sensor pixel 4021 located in the ghost detection area 402C where ghost light 403C is not generated. If the output value is smaller than the first predetermined value and larger than the second predetermined value, it is assumed that the sensor pixel 4031 is located in the ghost detection area 402C where the ghost light 403C is generated. Identify. The camera control unit 210 stores, in the EEPROM 211, the coordinates of the sensor pixel 4031 located in the area where the ghost light 403C of the ghost detection area 402C identified in this way is generated.

  FIG. 15 is a flowchart illustrating the procedure of the focus adjustment process in the first embodiment. The processing described below may be performed by the camera control unit 210 or may be performed by the control unit included in the focus detection device 207.

  First, a ranging operation is started in step S1. This is performed by the photographer operating a specific button of the imaging apparatus 200 and the operation detection unit 213 detecting the operation.

  Next, in step S2, the coordinates of the sensor pixel 4031 located in the area where the ghost light 403C has been generated when the uniform luminance surface light source is incident, which are stored in the EEPROM 211, are read, and the output of the sensor pixel 4031 at that coordinate is read out. obtain. Here, it is assumed that the accumulation times of the imaging area 401 and the ghost detection area 402 are set to be the same.

  Subsequently, in step S3, the generation of ghost light 403C is detected from the output of the sensor pixel 4031 obtained in step S2. Specifically, when the output value from the sensor pixel 4031 is larger than the second predetermined value, it is detected that the ghost light 403C is generated, and the process proceeds to step S4. On the other hand, when the output value from the sensor pixel 4031 is equal to or less than the second predetermined value, it is detected that the ghost light 403C is not generated, and the process proceeds to step S8 to perform correlation calculation to calculate the defocus amount. .

  In step S4, the location where the ghost light is generated in the focus detection sensor 400 is specified from the positional relationship between the sensor pixel 4031 and each of the imaging regions 401A to 401D. The specific method will be described later.

  In step S5, it is determined whether ghost light is generated in the imaging regions 401A to 401D based on the generation position of the ghost light identified in step S4. If it is determined that ghost light is not generated in the imaging regions 401A to 401D, the ghost light does not affect the correlation calculation result, and the process proceeds to the correlation calculation in step S8. On the other hand, when it is determined that ghost light is generated in the imaging regions 401A to 401D, the process proceeds to step S6.

  In step S6, it is determined whether the predicted ghost light generation position on the imaging regions 401A to 401D is a place having an influence on the defocus amount calculation. Whether the defocus amount calculation is affected depends on whether the focus detection line of the focus detection sensor 400 is in the region where the ghost light generation position is predicted, whether the focus detection line is present, and the photographic lens 100 attached to the imaging device 200. Judge by type. When it is determined that the defocus amount calculation is not affected, the process proceeds to step S8. On the other hand, when it is determined that the defocus amount calculation is affected, the process proceeds to step S7.

  At step S7, the focus detection line is reset. If it is determined in step S6 that the defocus amount calculation is affected, there is a high possibility of erroneous distance measurement if the output of the imaging region in which ghost light is generated is used for correlation calculation. Therefore, when ghost light is generated on the focus detection line, the distance measurement range is reset so as to exclude the generation position (specific position) of the ghost light from the distance measurement range.

  FIG. 16 is a diagram for explaining the method of resetting the focus detection line in step S7 of FIG.

  FIG. 16A shows the imaging regions 401A and 401B, the ghost detection regions 402A and 402B, the focus detection lines 401A-2 and 401B-2, and the incident ghost light 403D.

  As shown in FIG. 16A, when ghost light 403D is generated on the focus detection line 401A-2, its sensor output waveform is as shown in FIG. 16B. Since the generation location of the ghost light is specified in step S4, it is possible to predict at which position on the focus detection lines 401A-2 and 401B-2 the ghost light is incident. In this case, the sensor output waveform of the gray portion in FIG. 16B, which is predicted to generate ghost light 403D in step S7, is excluded from the distance measurement range. If correlation calculation is performed in this state, it is possible to prevent erroneous distance measurement due to ghost light.

  Although only the case where the correlation direction is the Y direction is described in FIG. 16, the focus detection line is similarly reset in step S7 when the correlation direction is the X direction.

  Returning to FIG. 15, after resetting the focus detection line in this way, correlation calculation and defocus amount calculation are performed in step S8. Thereafter, waveform reliability is evaluated in step S9, and in step S10, a focus detection line with high waveform reliability evaluated in step S9 is selected. Next, in step S11, correlation calculation and defocus amount calculation are performed using the sensor output waveform of the focus detection line selected in step S10, and the focus lens 101 is driven based on the calculated defocus amount. , End this process.

  Next, the method for identifying the location where the ghost light is generated in step S4 will be described in detail.

  A ray of light which causes ghost light on the focus detection sensor 400 by being reflected by a structure in the focus detection device 207 passes through the aperture stop 302 and the secondary imaging lens unit 303. Therefore, the position of ghost light generated by the focus detection sensor 400 can be analogized from the positional relationship between the apertures 302A to 302D of the multi-aperture stop and the secondary imaging lenses 303A to 303D.

  The analogy method will be described with reference to FIG.

  Thereafter, when it is detected that ghost light 403C is generated based on the output from the sensor pixel 4031 in step S3 of FIG. 15, the position of the ghost light 403C is specified from the coordinates of the sensor pixel 4031. When sensor pixels 4031 exist continuously, their center coordinates are specified as ghost light 403C. The positional relationship between the specified position of the ghost light 403C and the center coordinates of the imaging regions 401A to 401D is obtained by calculation. For example, the distances a (X direction) and b (Y direction) from the center coordinates of the imaging region 401C to the ghost light 403C are obtained two-dimensionally.

  The distances from the center coordinates of the imaging regions 401A to 401D are two-dimensionally determined in the same manner for the other ghost lights 403A and 403B. At this time, there must be a combination in which the two-dimensional distance between a certain ghost light and a certain imaging region is approximately equal to the two-dimensional distance between the other ghost light and another imaging region. In the example of FIG. 11, the combination of the imaging area 401A and the ghost light 403A, the imaging area 401B and the ghost light 403B, and the imaging area 401C and the ghost light 403C corresponds to this.

  When such a combination exists, it is found that there is an imaging area (imaging area 401D in the example of FIG. 11) in which the corresponding ghost light can not be detected. Since the central coordinates of the imaging region 401D and the two-dimensional distance of the ghost light corresponding thereto are also substantially equal to the two-dimensional distance in the above combination, the ghost light not detected when entering the uniform luminance surface light source Even, its position can be analogized. In the example of FIG. 11, it can be inferred that the position of the ghost light 403D not detected when the uniform luminance surface light source is incident is on the imaging region 401A. In the range where the ghost light 403D occurs, an increase in the amount of light due to the ghost light is predicted in the sensor output.

  By analogizing the position of the ghost light by the above method, it is possible to perform an appropriate correction process on a range in which the increase in the amount of sensor output of the imaging region 401 due to the ghost light is predicted.

  The prediction method of the generation position of the ghost light on the imaging region 401 is not limited to the above method. For example, as shown in FIG. 13C, in the case where continuous ghost light is incident on the ghost detection area 402 (when linear ghost light is generated), imaging in which a linear ghost reaches There is a method of analogizing the range on the area 401. Further, in this embodiment, the generation location of the ghost light is specified in step S4. However, it is performed when the coordinates of the sensor pixel 4031 located in the area where the ghost light is generated when the uniform luminance surface light source is incident are stored in the EEPROM 211. You may do it.

  As described above, in the configuration of the first embodiment, ghost light is detected from the output of the ghost detection region 402 where no light beam enters unless ghost light is generated. As a result, ghost light can be accurately detected without being affected by the subject image. In the configuration of the first embodiment, the position where ghost light is generated is predicted from the output obtained from the ghost detection region 402 provided around the imaging region 401 provided in the range where the subject image is formed. Thus, as in the prior art, in order to predict the position and intensity at which ghost light is generated, it is necessary to prepare correction data in accordance with the type of shooting lens that can be attached to the imaging apparatus 200, the subject distance, and the like in advance. Absent. Further, in the configuration of the first embodiment, the coordinates of sensor pixels 4031 located in an area where ghost light occurs in the ghost detection area 402 are stored in advance for each individual in the focus detection device 207. As a result, whether or not the ghost light 403C is generated during the focus adjustment process can be detected not from the output of the entire ghost detection area 402 but from the output of only the sensor pixel 4031, and the calculation processing load can be reduced. This is because the sensor pixel in which the ghost light generated in the ghost detection region 402 is located when a light beam from a uniform luminance surface light source having a size enough to cover the exit pupil of the photographing lens 100 is incident on the photographing lens 100. Achieved by identifying as 4031. Thereby, ghost light that may be generated in the ghost detection region 402 can be extracted regardless of the light source position in the exit pupil of the photographing lens 100. Further, the incident position of the ghost light in the imaging area 401 is predicted based on the stored coordinates of the sensor pixel 4031 located in the area where the ghost light is generated. As a result, the position of the ghost light generated in the imaging region 401 can be predicted even if the incident state of the light beam that generates the ghost light on the focus detection sensor 400 changes depending on the imaging conditions in the focus adjustment processing. That is, even if there is a situation in which the shape of the ghost light differs depending on the relationship between the internal structure and the light source position, or a situation in which the ghost light generated in the imaging area 401 is extremely weak and difficult to detect, the imaging area The position of ghost light generated in 401 can be predicted. By resetting the focus detection line according to the predicted position of the ghost light, it becomes possible to exclude the influence of the ghost light from the ranging range.

(Example 2)
In the second embodiment of the present invention, a method will be described in which the ghost detection result is used for distance measurement calculation in a method different from the above-described first embodiment of the present invention. The configurations of the photographing lens 100, the imaging device 200, the focus detection device 207, and the like are the same as in the first embodiment, and thus the description thereof is omitted. The differences from the first embodiment are mainly described below.

  FIG. 17 is a flowchart illustrating a procedure of focus adjustment processing according to the second embodiment. About the step of the same content as the focus adjustment process in Example 1 shown in FIG. 15, the same step number is attached | subjected and the duplicate description is abbreviate | omitted.

  The present process is different from the focusing process of the first embodiment in that step S100 is executed instead of step S7. That is, in the first embodiment, the focus detection line is reset so that ghost light is generated in step S7 and the entry point is excluded. On the other hand, in the second embodiment, in step S100, the waveform reliability of the focus detection line in which ghost light is generated is reset to be low. As a result, there is a low possibility that the defocus amount calculated using the sensor output waveform of the focus detection line in which ghost light is generated is adopted for driving the focus lens 101.

  As described above, in the configuration of the second embodiment, the waveform reliability for focus detection is reduced at a specific location in the imaging region 401 based on the output obtained from the ghost detection region 402. As a result, when the ghost light generation range is wider than in the case of Example 1 and a method of excluding only a specific range on the focus detection line from the ranging range can not be taken, the focus detection line in which the ghost light is not generated The defocus amount is calculated using the sensor output waveform of This makes it possible to accurately detect the focus.

(Example 3)
In the third embodiment of the present invention, a method of correcting the influence of ghost light on the storage time control of the focus detection sensor 400 will be described.

  First, accumulation time control of the focus detection sensor 400 will be described.

  The focus detection sensor 400, which is a photoelectric conversion element, can adjust the time for accumulating the charge. This is performed to set an appropriate accumulation time according to the light amount of the subject. In other words, the focus detection sensor 400 sets the accumulation time longer for a dark subject and shorter for a bright subject. In general, charge accumulation is stopped immediately before the output of any of the pixels in the focus detection sensor 400 is saturated.

  Now, let us consider the case where ghost light having a larger amount of light is generated in the imaging region 401 than the ghost light assumed in the first and second embodiments. In this situation, the amount of ghost light is several times the amount of light from the subject. In this case, the accumulation of electric charge in the focus detection sensor 400 ends immediately before the output of the pixel at the location where the ghost light is generated is saturated. Then, since the amount of ghost light is significantly larger than that of the subject, there is a problem that a sufficient amount of light cannot be obtained from the subject.

  Therefore, in the third embodiment, when a strong amount of ghost light is detected from the ghost detection area 402, the accumulation saturation determination of the imaging area 401 is changed based on the output obtained from the ghost detection area 402.

  FIG. 18 is a flowchart illustrating a procedure of focus adjustment processing according to the third embodiment. Steps having the same contents as those in the focus adjustment process in the second embodiment shown in FIG. 17 are denoted by the same step numbers, and redundant description is omitted.

  This process differs from the focus adjustment process of the second embodiment in that the determination process of step S200 is executed between step S5 and step S6, and if NO, steps S201 and S202 are executed.

  If it is determined in step S5 that ghost light is generated in the imaging region 401, the process proceeds to step S200. In step S200, the accumulation time (T1) in the focus detection line in the imaging area 401 where ghost light is predicted to be generated is compared with the accumulation time (T2) in the ghost detection area 402.

  For example, when a predetermined threshold P is set and the relationship of T1> T2 × P is established (YES in step S200), ghost light in the imaging region 401 is ignored as 1 / P or less, and the process proceeds to step S6. move on. On the other hand, if not (NO in step S200), it is determined that a sufficient amount of light can not be obtained from the subject due to the influence of ghost light in the imaging area 401, and accumulation saturation judgment is made for areas where ghost light generation is expected. It excludes from (step S201). Thereafter, charge accumulation in the imaging region 401 is performed again (step S202), and the process proceeds to step S100.

  As described above, in the configuration of the third embodiment, the specific region of the imaging region 401 is excluded from the accumulation saturation determination based on the output obtained from the ghost detection region 402. As a result, even when ghost light having a larger amount of light than the subject image is incident on the focus detection sensor 400, it is possible to perform focus detection with high accuracy.

(Example 4)
In the fourth embodiment of the present invention, when continuous ghost light (hereinafter referred to as “linear ghost light”) is generated on the focus detection sensor 400, ghost detection in which part of the linear ghost light is detected A method of inferring the generation range of the linear ghost light on the imaging region 401 based on the output of the region 402 will be described. The configurations of the photographing lens 100, the imaging device 200, the focus detection device 207, and the like are the same as in the first embodiment, and thus the description thereof is omitted.

  FIG. 19 is an enlarged view of the vicinity of the ghost detection area 402C in FIG. 8 where linear ghost light is generated.

  The adjacent pixel group 402C-1a is a pixel group adjacent to the imaging region 401C in the ghost detection region 402C.

  The linear ghost light 403C-2 is a ghost light of a portion located in the imaging region 401C among the linear ghost light generated on the focus detection sensor 400. The linear ghost light 403 </ b> C- 3 is ghost light of a portion located in the ghost detection region 402 </ b> C among the linear ghost light generated on the focus detection sensor 400.

  The linear ghost lights 403C-2 and 403C-3 are light reflected at the opening end of the opening 300A of the field mask 300 in FIG. When light is reflected at the opening 300 </ b> A near the planned imaging plane of the photographic lens 100, linear ghost light close to the shape of the reflecting portion is projected onto the focus detection sensor 400. As shown in FIG. 19, when the linear ghost light 403C-3 is detected in the adjacent pixel group 402C-1a, it can be determined that the linear ghost light 403C-2 is generated in the imaging region 401C.

  The operation of detecting the generation range of the linear ghost lights 403C-2 and 403C-3 will be described below with reference to FIGS.

  FIG. 20 is a view showing the vicinity of the linear ghost lights 403C-2 and 403C-3 of FIG. 19 for each pixel.

  FIG. 21 is a flowchart of the focusing process in the fourth embodiment. The processing described below may be performed by the camera control unit 210, or may be performed by the control unit included in the focus detection device 207. The same step numbers are assigned to steps having the same contents as the focus adjustment process in the first embodiment shown in FIG. 15, and duplicate explanations are omitted.

  In step S301, the photographer starts a ranging operation. This is performed by the photographer operating a specific button of the imaging apparatus 200 and the operation detection unit 213 detecting the operation.

  In step S302, the output of the adjacent pixel group 402C-1a is obtained.

  In step S303, the presence or absence of the generation of the linear ghost light 403C-3 is determined based on the presence or absence of the output of the adjacent pixel group 402C-1a obtained in step S302. When it is determined that there is an output from the adjacent pixel group 402C-1a and the linear ghost light 403C-3 is generated (YES in step S303), the process proceeds to step S304. On the other hand, when it is determined that there is no output from the adjacent pixel group 402C-1a and the linear ghost light 403C-3 is not generated (NO in step S303), the process proceeds to step S306.

  In step S304, the generation range of the linear ghost light 403C-3 is specified from the output of the adjacent pixel group 402C-1a, and the generation range of the linear ghost light 403C-2 in the imaging region 401 is specified from the specified generation range. I guess. Specifically, the range in which the linear ghost light 403C-3 is extended toward the imaging region 401C is analogized as the generation range of the linear ghost light 403C-2. If this analogy is completed, it will progress to step S305.

  In step S305, the distance measurement range of the focus detection line in the generation range of the linear ghost light 403C-2 estimated in step S304 is reset. When resetting of the distance measurement range is completed, the processing of steps S8 to S9 is executed, and the present processing is ended.

  The linear ghost light shown in FIG. 19 does not occur in the imaging regions 401A, 401B, and 401D as described above, but only occurs in the imaging region 401C, but is not limited thereto. That is, in the fourth embodiment, the light beam reflected by the opening 300A of the field mask 300 passes through the opening 302C of the multi-aperture stop 302, and the secondary imaging lens 303C makes one linear ghost light in the range of the imaging region 401C. Is occurring. However, even if a plurality of linear ghost lights are generated in the range of the imaging regions 401A, 401B and 401D by the secondary imaging lenses 303A, 303B and 303D after passing through the apertures 302A, 302B and 302D of the porous stop 302 The method of can be applied.

  As described above, in the configuration of the fourth embodiment, the position of the linear ghost light incident in the imaging region 401 is estimated based on the output obtained from the ghost detection region 402. This makes it possible to exclude the influence of ghost light only in the necessary range, and to perform focus detection with high accuracy.

(Example 5)
In the fifth embodiment, a method will be described in which an image signal is corrected using a ghost detection result and used for distance measurement calculation, in a method different from the first embodiment to which the present invention described above is applied.

(1) First, as an example of the correction operation, the case where the accumulation time of the imaging area 401 and the ghost detection area 402 is the same will be described.

  FIG. 22 is a diagram illustrating the positional relationship of ghost light when the light beam 403 that generates ghost light is incident on the focus detection sensor 400 in the fifth embodiment.

  The ghost lights 403A to 403D are ghost light generation positions on the focus detection sensor 400. As described above, the ray of light 403 causing ghost light passes through the aperture stop 302 and the secondary imaging lens unit 303. Therefore, on the focus detection sensor 400, four ghost lights 403A to 403D appear corresponding to the apertures 302A to 302D of the aperture stop 302 and the secondary imaging lenses 303A to 303D. In the fifth embodiment, among these ghost lights 403A to 403D, the ghost lights 403A to 403C are incident on the ghost detection area 402C, and the ghost light 403D is incident on the imaging area 401A.

  The focus detection line 401A-2 is in the imaging area 401A, and is provided in an area corresponding to the focus detection range 500 'of FIG. The focus detection line 401B-2 is in the imaging region 401B, and is similarly provided in a region corresponding to the focus detection range 500 'in FIG. The focus detection line 401C-2 is in the imaging region 401C, and is similarly provided in a region corresponding to the focus detection range 500 'in FIG. The focus detection line 401D-2 is in the imaging region 401D, and is similarly provided in a region corresponding to the focus detection range 500 'in FIG. Each focus detection line 401A-2, 401B-2, 401C-2, 401D-2 is arranged in the same direction as the direction (correlation direction) for dividing the image into pupils.

  The ghost detection lines 402C-1 to 402C are provided in the ghost detection area 402C at positions corresponding to the ghost lights 403A to 403C. The ghost detection lines 402C-1 to 402C-3 are provided in parallel to the Y direction, and 402C-4 to 6C are provided in parallel to the X direction. In the fifth embodiment, similarly to the first embodiment, the light beam from the uniform luminance surface light source is incident on the photographing lens 100, and the coordinates of the sensor pixels located in the ghost detection region 402C where the ghost lights 403A to 403C are generated. Is stored in the EEPROM 211. Thereafter, ghost detection lines 402C-1 to 402C-6 are set based on the stored coordinates. Further, in the fifth embodiment, when the coordinates of the sensor pixel are stored in the EEPROM 211, the coordinates of the region predicted to generate ghost light in the imaging region 401 are also stored in the EEPROM 211 in the same manner as in the first embodiment. Be done.

  FIG. 23 shows the sensor output waveform of the focus detection line and the sensor output waveform of the ghost detection line in the fifth embodiment when ghost light 403A to D are generated on the focus detection sensor 400 when the subject is a white crosshair. FIG. Here, a white cross line (a line parallel to the X direction and the Y direction) is photographed as the subject, and a part of the line parallel to the Y direction of the white cross line is selected as the focus detection range. An example will be described. On the focus detection line 401A-2, a white single line image is formed as a subject image, and at the same time, ghost light 403D is generated. On the other hand, since no ghost light is generated in the focus detection lines 401B-2, 401C-2, and 401D-2, only a single white line image that is a subject image is formed. In addition, only ghost lights 403A to 403C are detected in the ghost detection lines 402C to 402, respectively. The ghost lights 403A to 403D have almost the same intensity because the members existing from the structure that reflects the light beam 403 that generates the ghost light to the focus detection sensor 400 are the same.

  As described above, the sensor output waveform of the focus detection line 401A-2 does not have an accurate light amount distribution of the subject. Therefore, the light amount distributions of the two sensor output waveforms of the focus detection line 401A-2 and the focus detection line 401B-2 do not match, and when the correlation operation is performed based on these light amount distributions, the defocus amount with high accuracy Cannot be obtained, and the accuracy of focus adjustment also decreases.

  Therefore, in the fifth embodiment, based on the output obtained from the ghost detection area 402, the output of the imaging area 401 is corrected to perform focus detection. Hereinafter, the focus adjustment processing in the fifth embodiment will be described with reference to FIGS. The processing described below may be performed by the camera control unit 210 or may be performed by the control unit included in the focus detection device 207.

  FIG. 24 is a flowchart illustrating the procedure of the focusing process in the fifth embodiment.

  In step S501, a ranging operation is started. This is performed by the photographer operating a specific button of the imaging apparatus 200 and the operation detection unit 213 detecting the operation.

  In step S <b> 502, an accumulation time is set for the imaging region 401 and the ghost detection region 402. Here, the accumulation time of the imaging area 401 and the ghost detection area 402 is set to be the same, and the process proceeds to step S3. The setting of this accumulation time will be described in detail later.

  In step S503, the outputs of the imaging area 401 and the ghost detection area 402 are obtained based on the accumulation time set in step S502. That is, as shown in FIG. 23, a light amount distribution which is a sensor output waveform is obtained.

  In step S504, the output in the imaging area 401 is corrected from the output of the ghost detection area 402 obtained in step S503. Specifically, first, among the focus detection lines 401A-2, 401B-2, 401C-2, and 401D-2, the focus detection line at a position overlapping the coordinates of the area where ghost light is predicted to occur in the EEPROM 211 is Detect if there is. As a result of detection, if there is such a focus detection line (in this embodiment, the focus detection line 401A-2), the output is obtained. Next, among the ghost detection lines 402C-1 to 402C-6, the output of the ghost detection line (ghost detection line 402C-1 in the present embodiment) parallel to the Y direction is acquired in the same manner as the focus detection line 401A-2 that acquired the output. Do. Thereafter, the output of the ghost detection line 402C-1 is subtracted from the output of the focus detection line 401A-2.

  FIG. 25 is a diagram for describing a method of correcting the output of the imaging region 401 in step S504 of FIG.

  As described above, the light beam 403 causing ghost light 403A-D by the structure in the focus detection device 207 passes through the multi-aperture stop 302 and the secondary imaging lens unit 303, and the focus detection sensor with a specific positional relationship. Incident on 400. As described above, the ghost lights 403A to 403D have almost the same intensity. Therefore, as shown in FIG. 25, by subtracting the output of the ghost detection line 402C-1 from the output of the focus detection line 401A-2, only the output by the ghost light is excluded and only the output by the subject image can be obtained. it can.

  Here, in order to correct the focus detection line 401A-2 parallel to the Y direction, the output of the ghost detection line 402C-1 in the same direction is used. For example, if the ghost light existing on the focus detection line 401C-2 is corrected, the output of the ghost detection line in the same direction (any one of 402C-4 to 6 in the case of FIG. 22) may be used.

  Returning to FIG. 24, when the output correction in the imaging region 401 is completed, the process proceeds to step S505.

  In step S505, correlation calculation and defocus amount calculation are performed using the output corrected in step S504. When the calculation of the defocus amount is completed, the process proceeds to step S506.

  In step S506, the focus lens 101 is driven based on the defocus amount calculated in step S505. When driving of the focus lens 101 is completed, the present process ends.

(2) Next, as an example of the correction operation, a case where the focus detection sensor 400 that is a photoelectric conversion element adjusts the charge accumulation time for each region will be described.

  The focus detection sensor 400 can set an appropriate accumulation time according to the light amount of the subject by adjusting the time for accumulating the charge for each area. For example, the focus detection sensor 400 sets the accumulation time long for a dark subject, and shortens the accumulation time for a bright subject.

  In general, in order to more accurately capture the light amount distribution of the subject image, the charge accumulation is stopped immediately before any output of the pixels in the set focus detection line is saturated. Further, since the subject image formed for each focus detection line is different, the charge accumulation time is controlled for each pair of focus detection lines. In the example of FIGS. 22 and 23, the same accumulation time 1 is set for the pair of focus detection lines 401A-2 and 401B-2, and the other pair of focus detection lines 401C-2 and 401D-2 is used. Are set to the same accumulation time 2. However, since the accumulation times 1 and 2 are controlled separately, they are not necessarily the same.

  On the other hand, since only ghost light is not incident on the ghost detection area 402, the output is very small when the ghost light is not incident. In addition, even when ghost light is incident, the light beam that causes the ghost light is reflected by the structure and then is incident on the focus detection sensor 400, so the amount of light when the distance measurement light beam is incident on the imaging region 401 The amount of light is smaller than. Therefore, when charge accumulation is performed until immediately before the output of the pixel is saturated in the ghost detection area 402, the accumulation time becomes longer than that of the imaging area 401. When the accumulation time of the ghost detection area 402 becomes long, the time required for focus detection becomes long, which causes a problem that the responsiveness of focus detection is deteriorated.

  Thus, in the fifth embodiment, such an issue is addressed by controlling the accumulation time of the ghost detection area 402 based on the accumulation time of the imaging area 401.

  The accumulation time control in the specific embodiment 5 will be described with reference to FIG.

  FIG. 26 shows the accumulation time of the sensor output waveform of the focus detection line and the sensor output waveform of the ghost detection line in Example 5 when ghost light is generated in the focus detection sensor 400 when the subject is a general object. It is a figure which shows control. Here, a general subject refers to a landscape, a person or the like. That is, FIG. 26 is different from FIG. 23 in which the subject to be photographed is a white cross line.

  As shown in FIG. 26, the accumulation time 1 set in the focus detection lines 401A-2 and 401B-2 is 100 ms, and the accumulation time 2 set in the focus detection lines 401C-2 and 401D-2 is 50 ms. At this time, the accumulation time of the ghost detection lines 402C-1 to 402C-6 is set to 100 ms in accordance with the focus detection lines 401A-2 and 401B-2 in which the accumulation time 1 longer than the accumulation time 2 is set.

  When the focus detection lines 401A-2 and 401B-2 are selected for focus detection, the same correction processing as that described with reference to FIG. 25 is performed. That is, the output of the ghost detection line 402C-1 is subtracted from the output of the focus detection line 401A-2. Since both the ghost detection line 402C-1 and the focus detection line 401A-2 have an accumulation time of 100 ms, the amount of ghost light on the focus detection line 401A-2 is equal to the amount of ghost light on the ghost detection line 402C-1. This is because they can be regarded as equal.

  On the other hand, when the focus detection lines 401C-2 and 401D-2 are selected for focus detection, correction is performed based on the output of the ghost detection line 402C-4. Since the focus detection line 401C-2 has the accumulation time 2 but the accumulation time 1 of the ghost detection line 402C-4, the output of the ghost detection line 402C-4 is directly subtracted from the output of the focus detection line 401C-2. You can not do it. It is necessary to multiply the output of the ghost detection line 402C-4 by the accumulation time difference. In this example, after multiplying the output of the ghost detection line 402C-4 by the accumulation time 2 / accumulation time 1 = 50 ms / 100 ms = 0.5, the ghost light is corrected by subtracting it from the output of the focus detection line 401C-2. Is done. The above correction process is performed in step S504 in FIG.

  Contrary to the above correction method, there is a case where the same effect cannot be obtained by doubling the output of the focus detection line 401C-2 and subtracting the output of the ghost detection line 402C-4. In general, the longer the accumulation time of the photoelectric conversion element, the higher the S / N output. That is, since the focus detection line 401C-2 has a shorter accumulation time than the ghost detection line 402C-4, the output S / N is also not better than the ghost detection line 402C-4. In addition, since the output of the focus detection line 401C-2 whose S / N is not good is doubled, the reliability of the waveform is improved rather than multiplying the output waveform of the ghost detection line 402C-4 described above by 0.5. This is because it will be inferior. Therefore, in the fifth embodiment, the accumulation of the ghost detection area 402 is controlled based on the longest accumulation time 1 among the accumulation times of the imaging area 401.

  In the configuration of the fifth embodiment, the influence of ghost light is eliminated by subtracting the output of the ghost detection area 402 from the output of the imaging area 401. Therefore, unlike the prior art, it is not necessary to prepare correction data according to the type of the photographing lens that can be attached to the imaging apparatus 200, the subject distance, and the like in advance in order to predict the incident position and intensity of the ghost light.

  In the configuration of the fifth embodiment, the output of the imaging region 401 is corrected using the output of the ghost detection region 402 where no light beam enters unless ghost light is generated. As a result, it is possible to correct ghost light more accurately without being affected by the subject image. Further, a complicated calculation for separating the light amount of the ghost light and the light amount of the subject image is unnecessary, and correction can be performed in a shorter time.

  Further, in the configuration of the fifth embodiment, the output of the imaging region 401 is corrected based on the output of the ghost detection region 402 provided around the imaging region 401. This makes it possible to correct the influence of the ghost light even if the ghost light does not form an image in the imaging region 401 as in a backlight scene where the sun is outside the imaging region.

  In addition, in the configuration of the fifth embodiment, the accumulation time in the ghost detection area 402 is controlled based on the accumulation time of the imaging area 401. That is, the accumulation time in the ghost detection area 402 is set to the longest accumulation time among the accumulation times in the imaging area 401. Thereby, it is possible to appropriately set the accumulation time of the ghost detection area 402 and correct the influence of the ghost light without deteriorating the responsiveness of focus detection.

  As described above, according to the imaging apparatus 200 of the fifth embodiment, even when ghost light is incident on the focus detection sensor 400, focus detection can be performed with higher accuracy.

(3) Next, as an example of the correction operation, the focus detection sensor 400, which is a photoelectric conversion element, adjusts the charge accumulation time for each region. An extremely short case will be described.

  For example, when the illuminance of the object is high and the accumulation time is several ms, the accumulation time of the ghost detection area 402 is also set as several ms. In this case, as described above, the S / N of the output deteriorates as the accumulation time of the photoelectric conversion element is shorter. Therefore, the output by the ghost light in the ghost detection area 402 appears as an output waveform of the same level as the sensor noise, and the reliability of the output waveform in the imaging area 401 after performing the correction shown in FIG. 25 is reduced. There is a problem that it may be.

  Therefore, when a predetermined threshold value is set for the accumulation time and the accumulation time of the imaging region 401 is longer than the threshold value, the accumulation time of the ghost detection region 402 is set to be the same as the accumulation time of the imaging region 401. On the other hand, when the accumulation time of the imaging area 401 is equal to or less than the threshold, the accumulation time of the ghost detection area is made equal to the threshold. This addresses the above problem.

  Such measures will be specifically described below with reference to FIG.

  FIG. 27 is a diagram illustrating accumulation time control and thresholds related to accumulation time according to the fifth embodiment.

  The horizontal axis of the graph shown in FIG. 27 is the accumulation time of the imaging area 401, and the vertical axis is the accumulation time of the ghost detection area 402. In Example 5, the accumulation time of the ghost detection region 402 is determined based on the solid line in the graph of FIG.

  Specifically, as indicated by the hatched portion in FIG. 27, when the accumulation time of the imaging region 401 is longer than the threshold value T, the accumulation time of the ghost detection region 402 is set equal to the imaging region 401. For example, when the accumulation time in the imaging area 401 is 50 ms, the accumulation time of the ghost detection area 402 is also 50 ms.

  Here, the threshold value T in FIG. 27 is a time in which an output that can ignore the noise is obtained from the S / N characteristic of the focus detection sensor 400, and the time is short enough that the photographer cannot recognize the response delay. It is set to (a few ms to a few tens of ms). When the accumulation time of the imaging region 401 is equal to or less than the threshold value T, the accumulation time of the ghost detection region 402 is not set to be the same as that of the imaging region 401 and is always set to the threshold value T. As shown in FIG. 27, when the accumulation time in the imaging region 401 is 5 ms which is equal to or less than the threshold value T, the accumulation time in the ghost detection region 402 becomes the threshold value T.

  As described above, according to the fifth embodiment, when a predetermined threshold is set for the accumulation time of the ghost detection area 402 and the accumulation time of the imaging area 401 is longer than the threshold, the accumulation time of the ghost detection area 402 is set to the imaging area. The same as the accumulation time 401. On the other hand, when the accumulation time of the imaging area 401 is equal to or less than the threshold, the accumulation time of the ghost detection area 402 is made equal to the threshold. As a result, even in the case of a short accumulation time in which the influence of the noise of the photoelectric conversion element appears, the influence of the ghost light on the output of the focus detection sensor can be corrected and focus detection can be performed with high accuracy.

100 shooting lens 200 imaging device 207 focus detection device 210 camera control unit (calculation means)
300 field of view mask 302 porous stop 303 secondary imaging lens unit 400 focus detection sensor 401 imaging area (first sensor area)
402 Ghost detection area (second sensor area)

Claims (13)

A focus detection apparatus having a sensor for detecting an in-focus state of an external focus lens by a phase difference detection method,
The sensor is provided with a first sensor area in the image field of view and a second sensor area around the first sensor area.
Identification means for identifying an area where ghost light has occurred in the second sensor area when a predetermined light source is incident on the focus lens;
A first detection unit that detects whether or not the ghost light is generated based on an output from the identified area at the time of focusing of the focus lens;
A second detection unit that detects whether or not other ghost light is generated in the first sensor area when the ghost light is generated as a result of the detection by the first detection unit;
As a result of the detection by the second detection means, when the other ghost light is generated and the generation position of the other ghost light affects the detection of the in-focus state, the output of the sensor is selected. A focus detection apparatus comprising: third detection means for detecting a focused state by the phase difference detection method after correction.   2. The focus detection apparatus according to claim 1, wherein the predetermined light source is a uniform luminance surface light source having a size that covers an exit pupil of the focus lens.   The focus detection apparatus according to claim 1, wherein the first sensor area and the second sensor area are configured by the same sensor array.   The second detection means predicts a generation position of the other ghost light in the first sensor region from a positional relationship between the first sensor region and the identified region. The focus detection device according to any one of 1 to 3.   5. The focus detection according to claim 4, wherein the third detection unit excludes an output from a specific location in a region predicted by the correction as the generation position of the other ghost light of the sensor. apparatus.   5. The third detection means reduces waveform reliability of an output from a specific location in a region predicted by the correction as the generation position of the other ghost light of the sensor. Focus detection device as described.   The said 3rd detection means changes the accumulation saturation determination in said 1st sensor area | region based on the output obtained from said 2nd sensor area | region by the said correction | amendment. The focus detection apparatus according to item 1.   The first detection means is configured to change the ghost light into a linear ghost light when there is an output from an area adjacent to the first sensor area in the second sensor area during the focus adjustment of the focus lens. The focus detection apparatus according to claim 1, wherein the focus detection apparatus is determined to be And a holding unit that holds information of the area identified by the identification unit.
The first detection means determines the presence or absence of an output from the identified area based on the information read from the holding means. Focus detection device. A focus detection apparatus having a sensor for detecting an in-focus state of an external focus lens by a phase difference detection method,
The sensor is provided with a first sensor area in the range of the image field comprising a pair for each of the correlation directions, and a second sensor area around each of the first sensor areas.
First setting means for setting a focus detection line in each of the first sensor areas in a direction parallel to the correlation direction according to the focus detection range;
First identification means for identifying an area where ghost light has occurred in the second sensor area when a predetermined light source is incident on the focus lens;
Second identification means for identifying an area where it is predicted that another ghost light is generated in the first sensor area from the positional relationship between the first sensor area and the identified area;
Second setting means for setting a ghost detection line in a direction parallel to each of the correlation directions in the area identified by the first identification means;
When there is a first focus detection line at a position overlapping the area identified by the second identification means in the focus detection line during focusing of the focus lens, the output of the first focus detection line Correction means for correcting based on an output of a first ghost detection line set in the same direction as the first focus detection line among the ghost detection lines;
A focus detection apparatus comprising: a detection unit configured to detect an in-focus state by the phase difference detection method after the correction. And a holding unit that holds information of the area identified by the second identification unit.
The correction means determines the presence or absence of a first focus detection line at a position overlapping the area identified by the second identification means among the focus detection lines based on the information read from the holding means. The focus detection apparatus according to claim 10, characterized in that   12. The focus detection device according to claim 1, the focus lens, and a driving unit that drives the focus lens in an optical axis direction according to the detected focus state to perform focusing. An optical apparatus comprising: A focal point detection apparatus according to any one of claims 1 to 11, an image pickup device for generating an image, and a control means for controlling movement of the focus lens according to the detected in-focus state. An imaging device characterized by

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