JP2011145602A - Focus detector and imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a focus detector capable of appropriately detecting a focus state for a subject even when there is a bright subject in a background. <P>SOLUTION: The focus detector includes: a light receiving means 161 outputting light receiving signals corresponding to a plurality of focus detecting positions; a radiation means 140 radiating luminous flux to an object; a photometry means 162 obtaining first photometric values on the plurality of focus detecting positions in a state where the irradiation means 140 does not radiate the luminous flux, and second photometric values on the plurality of focus detecting positions in a state where the radiation means 140 radiates the luminous flux; a storage control means 162 performing storage control of the light receiving means according to storage conditions based on the light receiving signal corresponding to a second focus detecting position except a first focus detecting position where the photometric value equal to or above the predetermined value is obtained in terms of both the first photometric value and the second photometric value out of the plurality of focus detecting positions; and a focus detection means 163 detecting the focus state of an optical system based on the light receiving signal corresponding to the second focus detecting position. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a focus detection apparatus and an imaging apparatus.

2. Description of the Related Art Conventionally, there has been known a technique for detecting a focus by irradiating illumination light to an object with a low luminance as a whole.
(Patent Document 1).

JP 2008-129082 A

  However, in the conventional technique, when a bright subject such as a light source exists in the background, the focus is detected for the bright subject when the brightness of the main subject is darker than the bright subject even when the auxiliary light is irradiated. As a result, proper focus detection may not be performed.

  The problem to be solved by the present invention is to provide a focus detection apparatus capable of appropriately detecting a focus even when a bright subject is present in the background.

  The present invention solves the above problems by the following means. In addition, although the code | symbol corresponding to drawing which shows embodiment of this invention is attached | subjected and demonstrated, this code | symbol is only for making an understanding of invention easy, and is not the meaning which limits invention.

  [1] A focus detection apparatus according to the present invention receives a light beam corresponding to a plurality of focus detection positions set for a plurality of positions in an image plane by an optical system, accumulates charges, and outputs a light reception signal. A light receiving means (161d), an irradiating means (140) for irradiating a light beam to an object corresponding to the plurality of focus detection positions; A first photometric value obtained by measuring the luminous flux obtained in correspondence with each of the light beams, and a second photometric value obtained by measuring the luminous flux obtained in correspondence with each of the plurality of focus detection positions in a state in which the luminous flux is emitted by the irradiating means. Excluding the first focus detection position that obtains a photometric value greater than or equal to a predetermined value in both the first photometric value and the second photometric value among the plurality of focus detection positions. The second Accumulation control means (162) for accumulating and controlling the light receiving means according to an accumulation condition based on the light reception signal corresponding to the detection position, and a focus state of the optical system based on the light reception signal corresponding to the second focus detection position And a focus detection means (163) for detecting.

  [2] In the invention relating to the focus detection device, the accumulation control unit (162) may be configured to perform the operation based on the light reception signal corresponding to the focus detection position selected based on the focus state and the second photometric value. The accumulation condition can be determined.

  [3] In the invention related to the focus detection device, the accumulation control means (162) is configured to capture the predetermined focus state detected by the focus detection means in a state where the light flux from the irradiation means (140) is not irradiated. The light receiving means (161d) can be configured to perform accumulation control according to the accumulation condition based on the light reception signal corresponding to the focus detection position excluding the focus detection position corresponding to the distance.

  [4] In the invention related to the focus detection apparatus, the accumulation control unit (162) may be configured to determine the predetermined photographing distance according to the irradiation capability of the irradiation unit.

  [5] In the invention according to the focus detection apparatus, the focus detection unit (163) uses at least a part of a plurality of focus detection positions belonging to the second focus detection position as a focus detection position group, and the focus detection position. Selection means (163) for selecting any of the plurality of focus states detected for the group can be provided.

  [6] An imaging apparatus according to the present invention includes the focus detection apparatus.

  According to the present invention, even when there is a bright subject in the background, it is possible to appropriately detect the focus state with respect to the main subject.

FIG. 1 is a block diagram showing a camera 1 according to the present embodiment. FIG. 2 is a diagram illustrating an arrangement example of a plurality of focus detection areas set in the imaging screen of the imaging optical system. FIG. 3 is a diagram for explaining a correspondence relationship between a plurality of focus detection areas set in the imaging screen of the imaging optical system and the line sensor 161d of the focus detection module 161. FIG. 4 is a flowchart showing the operation of the camera 1 according to the first embodiment. FIG. 5 is a flowchart illustrating the control process at the time of illumination according to the first embodiment. FIG. 6 is a diagram illustrating an example of a scene of a subject imaged on the imaging screen of the imaging optical system. FIG. 7 is a diagram illustrating an example of a correspondence relationship between a subject imaged in the imaging screen of the imaging optical system illustrated in FIG. 6 and a plurality of focus detection areas set in the imaging screen of the imaging optical system. FIG. 8 is a flowchart showing the operation of the camera 1 according to the second embodiment. FIG. 9 is a flowchart showing a sensor region specifying control process and a charge accumulation control process according to the second embodiment.

  In the following, an embodiment in which the present invention is applied to a single-lens reflex digital camera will be described with reference to the drawings. However, the present invention can also be applied to other imaging devices such as a silver salt film camera.

<< First Embodiment >>
FIG. 1 is a block diagram showing a single-lens reflex digital camera 1 according to the present embodiment. The illustration and description of a general configuration of the camera other than the configuration related to the focus detection apparatus and the imaging apparatus of the present invention are partially omitted. To do.

  As shown in FIG. 1, the single-lens reflex digital camera 1 (hereinafter simply referred to as camera 1) of the present embodiment includes a camera body 100 and a lens barrel 200, and the camera body 100 and the lens barrel 200 are detachable. Combined as possible.

  The lens barrel 200 incorporates a photographing optical system including lenses 211, 212, 213 and a diaphragm 220.

  The focus lens 212 is provided so as to be movable along the optical axis L1 of the lens barrel 200, and its position is adjusted by the lens driving motor 230 while its position is detected by the encoder 260.

  The specific configuration of the moving mechanism along the optical axis L1 of the focus lens 212 is not particularly limited. For example, a rotating cylinder is rotatably inserted into a fixed cylinder fixed to the lens barrel 200, a helicoid groove (spiral groove) is formed on the inner peripheral surface of the rotating cylinder, and the focus lens 212 is fixed. The end of the lens frame is fitted into the helicoid groove. Then, by rotating the rotating cylinder by the lens driving motor 230, the focus lens 212 fixed to the lens frame moves linearly along the optical axis L1. The lens barrel 200 is provided with lenses 211 and 213 other than the focus lens 212. Here, the embodiment will be described by taking the focus lens 212 as an example.

  As described above, the focus lens 212 fixed to the lens frame by rotating the rotating barrel with respect to the lens barrel 200 moves straight in the direction of the optical axis L1, but the lens drive motor 230 as its drive source is operated by the lens mirror. The tube 200 is provided. The lens driving motor 230 and the rotating cylinder are connected by, for example, a transmission including a plurality of gears, and when the driving shaft of the lens driving motor 230 is driven to rotate in any one direction, the lens driving motor 230 is transmitted to the rotating cylinder at a predetermined gear ratio, and When the rotary cylinder rotates in any one direction, the focus lens 212 fixed to the lens frame moves straight in any direction of the optical axis L1. When the drive shaft of the lens drive motor 230 is rotated in the reverse direction, the plurality of gears constituting the transmission also rotate in the reverse direction, and the focus lens 212 moves straight in the reverse direction of the optical axis L1.

  The position of the focus lens 212 is detected by the encoder 260. As described above, the position of the focus lens 212 in the direction of the optical axis L1 correlates with the rotation angle of the rotating cylinder. Therefore, if the relative rotation angle of the rotating cylinder with respect to the lens barrel 200 is detected, the position is obtained. Can do.

  The encoder 260 according to the present embodiment includes an encoder 260 that detects the rotation of a rotating disk coupled to the rotational drive of the rotating cylinder with an optical sensor such as a photo interrupter, and outputs a pulse signal corresponding to the number of rotations. And the contact point of the brush on the surface of the flexible printed wiring board provided on either one of the rotating cylinders, and the brush contact provided on the other, the amount of movement of the rotating cylinder (in either the rotational direction or the optical axis direction) The detection circuit detects a change in the contact position according to (good).

  The aperture 220 has an aperture diameter centered on the optical axis L1 in order to limit the amount of light flux that passes through the imaging optical system and reaches the image sensor 110 provided in the camera body 100 and adjusts the amount of blur. It is configured to be adjustable. Adjustment of the aperture diameter by the aperture 220 is performed by transmitting an appropriate aperture diameter calculated in the automatic exposure mode from the camera control unit 170 to the aperture drive unit 240 via the lens control unit 250, for example. In addition, the adjustment of the aperture diameter is performed by a manual operation via the operation unit 150 provided in the camera body 100, and the set aperture diameter is transmitted from the camera control unit 170 to the aperture drive unit 240 via the lens control unit 250. Is also done. Note that the aperture diameter of the diaphragm 220 is recognized by the lens control unit 250.

  On the other hand, the camera body 100 includes a mirror system 120 for guiding the light flux from the subject to the image sensor 110, the finder 135, the lens 136, the photometric sensor 137, and the focus detection module 161. The mirror system 120 includes a quick return mirror 121 that rotates by a predetermined angle between the observation position and the imaging position of the subject around the rotation axis 123, and the quick return mirror 121 that is pivotally supported by the quick return mirror 121. And a sub mirror 122 that rotates in accordance with the rotation. In FIG. 1, a state where the mirror system 120 is at the observation position of the subject is indicated by a solid line, and a state where the mirror system 120 is at the imaging position of the subject is indicated by a two-dot chain line.

  The mirror system 120 is inserted on the optical path of the optical axis L1 in the state where the subject is in the observation position, and rotates so as to retract from the optical path of the optical axis L1 in the state where the subject is in the imaging position.

  The quick return mirror 121 is composed of a half mirror, and in a state where the subject is at the observation position, the quick return mirror 121 reflects a part of the light flux (optical axes L2 and L3) from the subject (optical axis L1). Then, the light is guided to the finder 135 and the photometric sensor 137, and a part of the light beam (optical axis L4) is transmitted to the sub mirror 122. On the other hand, the sub mirror 122 is configured by a total reflection mirror, and guides the light beam (optical axis L4) transmitted through the quick return mirror 121 to the focus detection module 161.

  Therefore, when the mirror system 120 is at the observation position, the light flux (optical axis L1) from the subject is guided to the finder 135, the photometric sensor 137, and the focus detection module 161, and the subject is observed by the photographer and exposure calculation is performed. And the focus state of the focus lens 212 is detected. Then, when the photographer fully presses the release button, the mirror system 120 rotates to the photographing position, and all the luminous flux (optical axis L1) from the subject is guided to the image sensor 110, and the photographed image data is stored in a memory (not shown). To do.

  The light flux (optical axis L2) from the subject reflected by the quick return mirror 121 forms an image on a focusing screen 131 disposed on a surface optically equivalent to the image sensor 110, and forms a pentaprism 133 and an eyepiece lens 134. It is possible to observe through. At this time, the transmissive liquid crystal display 132 superimposes and displays a focus detection area mark on the subject image on the focusing screen 131 and relates to shooting such as the shutter speed, aperture value, and number of shots in an area outside the subject image. Display information. As a result, the photographer can observe the subject, its background, and photographing related information through the finder 135 in the photographing preparation state.

  The photometric sensor 137 is composed of a two-dimensional color CCD image sensor or the like, and divides the photographing screen into a plurality of regions and outputs a signal corresponding to the luminance of each region in order to calculate an exposure value at the time of photographing. A signal detected by the photometric sensor 137 is output to the camera control unit 170 and used for automatic exposure control.

  The AF auxiliary light source 140 is controlled by a control signal from the camera control unit 170. The illumination light emitted from the AF auxiliary light source 140 may be, for example, illumination light having a uniform intensity as a whole or illumination light having a predetermined contrast pattern, and the type thereof is not particularly limited. .

  The operation unit 150 includes, for example, a shutter release button, a mode setting switch for setting various operation modes of the camera 1, and the operation unit 150 is used to switch between an autofocus mode / manual focus mode and an autofocus. An automatic selection AF mode for automatically selecting a focus detection area to be used for focus adjustment among the modes can be selected. The shutter release button switch includes a first switch SW1 that is turned on when the button is half-pressed and a second switch SW2 that is turned on when the button is fully pressed.

  The focus detection module 161 is a focus detection element for performing focus detection by the phase difference detection method, and is optically equivalent to the imaging surface of the image sensor 110 in the optical path of the light beam (optical axis L4) reflected by the sub mirror 122. It is fixed at the correct position.

  Here, FIG. 2 shows an arrangement example of a plurality of focus detection areas set in the photographing screen 50 of the photographing optical system. As shown in FIG. 2, a plurality of focus detection areas AFP are set in the shooting screen 50 of the shooting optical system. In the present embodiment, the focus detection module 161 corresponds to each focus detection area AFP. As will be described later, a plurality of a pair of line sensors 161d are provided, so that an image signal in each focus detection area AFP can be acquired. In the present embodiment, as indicated by AFP 1 to 51 in FIG. 2, 51 focus detection areas AFP are provided, and each position corresponds to a predetermined position in the imaging range of the image sensor 110. Note that the number and arrangement of the focus detection areas AFP are not limited to those shown in FIG.

FIG. 3 shows the correspondence between a plurality of focus detection areas set in the shooting screen 50 of the shooting optical system and the line sensor 161d of the focus detection module 161. As shown in FIG. 3, in this embodiment, a total of 11 line sensors 161d _{1 to} 161d ₁₁ are provided, the line sensor 161d ₁ is provided corresponding to the AFPs ₁ to 5, and the line sensor 161d ₂ Are provided corresponding to the AFPs 6 to 10, and similarly, the line sensors 161d _{3 to} 161d ₁₁ are provided corresponding to the AFPs ₁₁ to 51, respectively. Each of the line sensors 161d _{1 to} 161d ₁₁ is composed of a pair (two) of line sensors, but in FIG. 3, _{one of} the pair of line sensors constituting the line sensors 161d _{1 to} 161d ₁₁ is _one of them. Only the line sensor is shown. Furthermore, as shown in FIG. 3, each region _161d 10a _{~161d 10c} of the line sensor 161d ₁₀ corresponds to the focus detection area AFP46～48, by receiving the light beam in the region _{161d 10a} of the line sensor 161d ₁₀ obtained image signal which is the output as an image signal corresponding to AFP47, image signals obtained by receiving the light beam in the region _{161d 10b} of the line sensor 161d ₁₀ is outputted as an image signal corresponding to AFP46, the line sensor 161d ₁₀ An image signal obtained by receiving the light beam in the region 161d _10c is output as an image signal corresponding to the AFP48. Similarly, each region (not shown) in each of the pair of line sensors 161d _{1 to} 161d ₉ and 161d ₁₁ also corresponds to the focus detection areas AFP 1 to 45 and 49 to 51, respectively, and each of the pair of line sensors 161d ₃ to 161d ₃ image signal received in each region of 161d ₁₁ is output as an image signal corresponding to each focus detection area AFP1～45,49～51.

  Returning to FIG. 1, the AF-CCD control unit 162 controls accumulation conditions such as the gain and accumulation time of the line sensor 161 d of the focus detection module 161 in the autofocus mode, and is provided in the focus detection module 161. The image signals detected by the plurality of pairs of line sensors 161d are read in correspondence with the respective focus detection areas, and the read image signals are output to the camera control unit 170 and the defocus calculation unit 163.

Here, as described above, the pair of line sensors 161d of the focus detection module 161 are provided so as to correspond to the plurality of focus detection areas AFP, respectively, and the AF-CCD control unit 162 includes each pair of line sensors. The accumulation conditions such as gain and accumulation time are controlled every 161d. That is, a plurality of image signals corresponding to a plurality of focus detection areas corresponding to the same pair of line sensors 161d can be obtained under the same accumulation condition. For example, in the example shown in FIG. 3, because AFP46~48 corresponds to the same pair of line sensors 161d _10, AF-CCD controller 162, by controlling the accumulation conditions of the pair of line sensors 161d _10, Image signals corresponding to the AFPs 46 to 48 are obtained under the same accumulation conditions. Further, as will be described later, the AF-CCD control unit 162 irradiates the luminance (first luminance value) of the image signal and the illumination light for focus detection when the illumination light for focus detection is illuminated. The brightness (second brightness value) of the image signal in a state where the brightness is not detected is obtained, a focus detection area with high brightness is specified from each focus detection area, and the focus detection area corresponding to the focus detection area excluding the focus detection area with high brightness is supported. Based on the luminance, the accumulation conditions such as the gain and accumulation time of the line sensor 161d are controlled.

  The defocus calculation unit 163 converts the shift amount of the pair of image signals corresponding to the focus detection area sent from the AF-CCD control unit 162 into a defocus amount, and outputs this to the lens drive amount calculation unit 164. .

  Based on the defocus amount sent from the defocus calculation unit 163, the lens drive amount calculation unit 164 calculates a lens drive amount Δd corresponding to the defocus amount, and outputs this to the lens drive control unit 165. .

  The lens drive controller 165 drives the lens drive motor 230 based on the lens drive amount Δd sent from the lens drive amount calculator 164 and adjusts the position of the focus lens 212.

  The image sensor 110 is provided on the optical axis L1 of the light beam from the subject of the camera body 100 and at a specified image plane position of the photographing optical system including the lenses 211, 212, and 213, and a shutter 111 is provided in front of the image sensor 110. Is provided. The image sensor 110 is a device in which a plurality of photoelectric conversion elements are two-dimensionally arranged, and can be composed of a device such as a two-dimensional CCD image sensor, a MOS sensor, or a CID. The image signal photoelectrically converted by the image sensor 110 is subjected to image processing by the camera control unit 170 and then stored in a memory (not shown). Note that the memory for storing the photographed image can be constituted by a built-in memory or a card-type memory.

  The camera control unit 170 is composed of peripheral components such as a microprocessor and a memory, reads an image signal from the image sensor 110, performs predetermined information processing as necessary, and outputs it to a memory (not shown). In addition, the camera control unit 170 controls the entire camera 1 such as correction of captured image information, detection of the focus adjustment state of the lens barrel 200, and detection of the aperture adjustment state.

  Next, an operation example of the camera 1 according to the present embodiment will be described with reference to FIG. FIG. 4 is a flowchart showing the operation of the camera 1 according to this embodiment. In the following, a case will be described as an example in which the automatic selection AF mode for automatically selecting a focus detection area for use in focus adjustment is selected from among the autofocus modes.

First, in step S101, the camera control unit 170 confirms that the power is on and the automatic selection AF mode is selected from among the autofocus modes. Then, the process proceeds to step S102, and the focus detection module. Charge storage is performed by the line sensor 161 d of 161, and accumulation control is performed by the AF-CCD control unit 162. The amount of charge stored in the line sensor 161d corresponds to the brightness of each focus detection area, and the AF-CCD control unit 162 sets the signal information from the line sensor 161d in the imaging screen 50 of the imaging optical system. By reading out corresponding to each focus detection area, the brightness (first brightness value) of each focus detection area is measured. The AF-CCD control unit 162 controls the accumulation condition for each pair of line sensors 161d _{1 to} 161d ₁₁ .

In the automatic selection AF mode, when the shutter release button is half-pressed (see step S103), since the position of the area for focusing is not determined, the AF-CCD control unit 162 sets each pair. All focus detection areas corresponding to the respective line sensors 161d _{1 to} 161d ₁₁ are specified as sensor areas for focusing (AF sensor areas), and AF sensors corresponding to the respective line sensors 161d _{1 to} 161d ₁₁ The storage conditions such as the gain and storage time of the line sensor 161d are controlled according to the brightness of the image signal having the highest brightness among the brightnesses of the image signals in the region.

For example, as shown in FIG. 3, of the focus detection area AFP47~49 corresponding to the line sensor 161d _10, when the highest luminance of the focus detection area AFP47, AF-CCD controller 162, the luminance of the focus detection area AFP47 based on, to control the accumulation condition of the line sensor 161d _10.

  In step S103, the camera control unit 170 determines whether the shutter release button is half-pressed (the first switch SW1 is turned on). If it is determined that the first switch SW1 is on, the process proceeds to step S104. If it is determined that the first switch SW1 is not on, the process returns to step S101, and focus detection is performed until the first switch SW1 is turned on. Power storage by the line sensor 161d of the module 161 and output of the accumulated signal information are repeatedly performed.

  Next, in step S104, it is determined whether a condition for irradiating illumination light from the AF auxiliary light source 140 is satisfied. The irradiation condition of the AF auxiliary light source 140 is, for example, that the AF auxiliary light source 140 is irradiated when the brightness of each focus detection area is less than a predetermined value, and the AF auxiliary light source 140 is turned on when the brightness of each focus detection area is greater than or equal to a predetermined value. Do not irradiate. The AF-CCD control unit 162 transmits the luminance information of each focus detection area to the camera control unit 170, and the camera control unit 170 uses the luminance information read from the AF-CCD control unit 162 based on the illumination condition. It is determined whether or not the AF auxiliary light source 140 is irradiated.

  In step S104 of this example, it is determined whether or not to irradiate the AF auxiliary light source 140 based on the accumulation condition of the AF-CCD control unit 162. However, based on the luminance detected by the photometric sensor 137, AF is determined. It may be determined whether or not the auxiliary light source 140 is irradiated. Further, the AF-CCD control unit 162 may determine whether to irradiate the AF auxiliary light source 140 based on the illumination condition.

  When the camera control unit 170 determines not to irradiate the AF auxiliary light source 140, the process proceeds to step S106. When the camera control unit 170 determines to irradiate the AF auxiliary light source 140, the process proceeds to step S105.

  In step S105, illumination light is irradiated, and accumulation control is performed by the AF-CCD control unit 162 (control process during illumination light). Hereinafter, with reference to FIGS. 5 to 7, processing such as accumulation control by the AF-CCD control unit 162 in step S <b> 105 will be described. FIG. 5 is a flowchart of accumulation control of the line sensor 161d when irradiating illumination light according to the present embodiment. FIG. 6 is a diagram showing an example of a scene of a subject imaged on the imaging screen 50 of the imaging optical system, and FIG. 7 is an illustration of the subject imaged on the imaging screen 50 of the imaging optical system shown in FIG. It is a figure which shows an example of a correspondence with the some focus detection area set in the imaging | photography screen 50 of a system. 6 and 7 exemplify scenes in which the first subject (person) and the second subject (outside light) as the background are imaged in the imaging screen 50 of the imaging optical system.

If it is determined that irradiates AF auxiliary light source 140 in step S104, first, AF-CCD controller 162, for each line sensor 161d ₁ ~161d _11, in the corresponding focus detection area AFP1～51, highest respectively The focus detection area that is the luminance and the second highest luminance area are specified, and the respective luminances are compared (step S201). For example, as shown in FIG. 7, the focus detection area AFP1~5 corresponding to the line sensor 161d _1, since there is a first object, the brightness of the focus detection area AFP1 high to a first brightness of the focus detection area AFP3 2 The second highest. Further, in the focus detection area AFP26~30 corresponding to the line sensor 161d _6, since the light source of the second object is in the focus detection area AFP27, higher to a first luminance of the focus detection area AFP27, the brightness of the focus detection area AFP26 Suppose that it is the second highest.

In the case shown in FIG. 7, the AF-CCD control unit 162 specifies the focus detection area AFP1 as the highest brightness area from the focus detection areas AFP1 to AFP5, and detects the focus as the second highest brightness area. The area AFP3 is specified, and the difference between the brightness value of the focus detection area AFP1 and the brightness value of the focus detection area AFP3 is obtained. Further, the AF-CCD control unit 162 specifies the focus detection area AFP27 as the highest brightness area from the focus detection areas AFP26 to 30, and specifies the focus detection area AFP26 as the second highest brightness area. The difference between the luminance value of the focus detection area AFP27 and the luminance value of the focus detection area AFP26 is obtained. Similarly, the AF-CCD control unit 162 specifies the focus detection area of the maximum brightness value and the focus detection area of the second brightness value for each of the other line sensors 161d _{2 to} 161d ₁₁ , and calculates the difference between the brightness values. Take.

Next, in step S202, the AF-CCD control unit 162 compares the luminance value difference for each of the line sensors 161d _{1 to} 161d ₁₁ with a predetermined value, and if the luminance value difference is equal to or greater than the predetermined value, the maximum luminance is obtained. The focus detection area of the value is excluded from the AF sensor area, and the remaining focus detection area is set as the AF sensor area. On the other hand, when the difference in luminance value is less than the predetermined value, the AF-CCD control unit 162 does not exclude the focus detection area with the maximum luminance value from the AF sensor area, and sets all focus detection areas as AF sensor areas.

For example, as shown in FIG. 7, the focus detection area AFP1~5 corresponding to the line sensor 161d _1, the focus detection area AFP3 focus detection areas AFP1 and second luminance value of the maximum luminance value, both the first object Since there is no difference in luminance, the difference between the luminance value of the focus detection area AFP1 and the luminance value of the focus detection area AFP3 is small and smaller than a predetermined value. Therefore, the AF-CCD control unit 162 does not exclude the focus detection area AFP1 with the maximum luminance value from the AF sensor area, and sets all the focus detection areas AFP1 to AFP5 as AF sensor areas.

Further, in the focus detection area AFP26~30 corresponding to the line sensor 161d _6, the focus detection area AFP26 of the maximum luminance value is imaging the second object light source, has high luminance as compared with other areas, the focus The difference between the luminance value of the detection area AFP27 and the luminance value of the focus detection area AFP26 is large and larger than a predetermined value. Therefore, the AF-CCD control unit 162 excludes the focus detection area AFP27 having the maximum luminance value from the AF sensor area, and sets the remaining focus detection areas AFP26 and 28 to 30 as AF sensor areas. Thus, in the present example, when there is a high-luminance region due to a background light source or the like, the focus detection area corresponding to the high-luminance region can be excluded from the AF sensor region.

  Next, in step S203, the AF auxiliary light source 140 is turned on to emit auxiliary light.

  In step S204, the electric charge is stored by the line sensor 161d of the focus detection module 161, and the AF-CCD control unit 162 performs line sensor detection based on the brightness corresponding to the AF sensor area specified in step S202. The accumulation condition 161d is controlled.

AF-CCD controller 162, corresponding to each pair of line sensors 161d ₁ ~161d _11, among the luminance of the image signal in the AF sensor area identified at step S202, the brightness of the brightest high image signal Accordingly, control is performed under the accumulation conditions of the line sensor 161d. Here, in the AF-CCD accumulation control in step S204, the AF irradiation light 140 is turned on as compared with the AF-CCD accumulation control in step S102, and the accumulation of the line sensor 161d is performed under the same conditions as the accumulation conditions in step S102. If conditions are determined, there is a possibility of overflow. Therefore, in the AF-CCD accumulation control in step S204, the accumulation by the line sensor 161d is performed by taking into account the luminance due to the irradiation of the AF irradiation light 140, for example, by making the accumulation time of the line sensor 161d shorter than the accumulation time of step S102. Control by condition. Thereby, this example can prevent overflow.

Returning to FIG. 4, in step S <b> 106, when the AF auxiliary light source 140 is not irradiated, the regions of all focus detection areas corresponding to the respective pair of line sensors 161 d _{1 to} 161 d ₁₁ are set as AF sensor regions. When the defocus amount calculation processing for calculating the defocus amount is performed and the AF auxiliary light source 140 emits light, the defocus amount calculation processing for calculating the defocus amount of the AF sensor area specified in step S202 is performed.

  In step S106, the reliability of the calculated defocus amount is also determined.

  In subsequent step S107, the camera control unit 170 determines whether or not the defocus amount has been calculated for all focus detection areas belonging to the AF sensor area. If it is determined that the defocus amount has been calculated for all focus detection areas belonging to the AF sensor area, the process proceeds to step S108, while the defocus amount has not been calculated for all focus detection areas belonging to the AF sensor area. When it is determined that the defocus amount is calculated for all focus detection areas belonging to the AF sensor area, the defocus amount calculation is repeated.

  Next, in step S108, the camera control unit 170 performs a process (automatic selection AF process) for determining an optimum area position for focusing. The method of automatic selection AF processing is not particularly limited. For example, by selecting the focus detection area with the smallest defocus amount from the defocus amounts of the AF sensor area specified in step S102 or step S202, A method for selecting the closest focus detection area or a focus detection area located at the center in the shooting screen 50 among the focus detection areas of the AF sensor area specified in step S102 or step S202. A method is mentioned.

  In step S109, based on the automatic selection AF processing in step S108, the lens driving amount calculation unit 164 calculates the lens driving amount Δd corresponding to the defocus amount of the focus detection area for use in focus adjustment, and calculates the calculated lens. The drive amount Δd is output to the lens drive control unit 165.

  In step S110, the lens drive control unit 165 sends a drive command to the focus lens drive motor 230 via the lens control unit 250 based on the lens drive amount Δd calculated in step S112. Is driven.

  In step S109 and step S110, if there is no focus detection area that can be detected by the first automatic selection AF process, a scanning operation is performed. Specifically, the lens drive control unit 250 sends a lens drive signal to the focus lens drive motor 230, thereby driving the focus lens 212 in a predetermined direction and setting the defocus amount for each focus detection area. By performing the calculation, the focus state is searched.

  In step S111, the camera control unit 170 performs in-focus determination. For example, in the present embodiment, when the defocus amount in the focus detection area for focus adjustment is equal to or less than a predetermined value, it is determined to be in focus. If it is determined to be in focus, the process proceeds to step S112. On the other hand, if it is not determined to be in focus, the process returns to step S103, and the above-described processing is repeated until focus is achieved.

  In step S112, the camera control unit 170 determines whether or not the shutter release button is fully pressed (the second switch SW2 is turned on). When it is determined that the second switch SW2 is on, the process proceeds to step S113, and an image is picked up by the image sensor 110 (step S113). Thereby, an image focused on the main subject is captured, and the captured image is transmitted to the camera control unit 170 and subjected to predetermined processing, and then stored as image data in a memory (not shown). On the other hand, if it is determined in step S112 that the second switch SW2 is off, the process returns to step S103, and the above-described processing is repeated until the second switch SW2 is turned on.

  As described above, in this example, the brightness (first brightness value) of each focus detection area set in the photographing screen 50 is measured in a state where the AF auxiliary light source 104 is not turned on. A focus detection area in which a luminance value equal to or higher than a predetermined value among the luminance values of 1 is obtained is excluded, and the accumulation condition of the line sensor 161d is controlled based on the luminance of the excluded area. That is, the excluded area is an area including a point light source for night scenes, a background light source, and the like. Even when the AF auxiliary light source 140 is turned on, it is difficult for light from the AF auxiliary light source 140 to reach the area. This is an area where there is little change in luminance before and after the light source 140 is turned on. Therefore, as in this example, the accumulation condition of the line sensor 161d when the AF auxiliary light source 140 is turned on based on a focus detection area where the luminance change is large before and after the AF auxiliary light source 140 is turned on, excluding the area. By controlling this, accumulation control is performed on the area including the original subject.

  Thus, for example, when there is a bright subject such as a light source in the background, the accumulation control of the line sensor 161d is performed in an area excluding the subject and the autofocus process is performed. The accumulation control of the line sensor 161d is performed in correspondence with the subject, and the focus can be adjusted appropriately.

Note that, in step S202, this embodiment is excluded in the focus detection area corresponding to the line sensors 161d ₁ ~161d _11, when the difference in luminance value is larger than the predetermined value, the region of highest intensity from the AF sensor region However, another method may be used for specifying the area to be excluded. For example, an average value of luminance values may be taken in the focus detection area, and the area to be excluded may be specified by comparison with the average value. .

<< Second Embodiment >>
Next, 2nd Embodiment of this invention is described based on drawing. This example differs from the first embodiment described above in that the defocus amount is calculated before the AF auxiliary light source 104 is turned on. The description of the same configuration as that of the above-described first embodiment other than the above is incorporated as appropriate. FIG. 8 is a flowchart showing the operation of the camera 1 of this example, and FIG. 9 is a flowchart showing the sensor area specifying control process and the charge accumulation control process based on the AF auxiliary light source 104 of this example.

  As shown in FIG. 8, steps S301 to S303 and steps S308 to S313 are the same as steps S101 to S103 and steps S108 to S113 shown in FIG.

  When the shutter release button is half-pressed in step S303, a sensor area specifying process (step S304) and a charge accumulation control process based on the AF auxiliary light source 104 (step S305) are performed. Hereinafter, step S304 and step S305 will be described with reference to FIG.

  In step S304a, the camera control unit 170 determines the focus detection areas AFP1 to AFP51 (see FIG. 5) in the imaging screen 50 of the imaging optical system from the received signal from the line sensor 161d based on the accumulation condition set in step S302. 2) is calculated. Note that the defocus amount calculation method is the same as that in step S106 described above.

  Next, in step S304b, the camera control unit 170 reads lens information including information on the current positions of the lens 211, the lens 212, and the lens 213, information on the focal length, and the like.

  In step S304c, the camera control unit 170 reads auxiliary light type information. The auxiliary light type information includes information on the reach of auxiliary light to be used. When the AF auxiliary light source 140 is used, the type information of the AF auxiliary light source 140 is read as auxiliary light type information, and when using the external auxiliary light or the external strobe, the external information is attached respectively. The auxiliary light or strobe type information is read out.

  In step S304d, the AF sensor area is specified. The camera control unit 170 extracts an area on the infinity side with high brightness from the accumulation condition of the line sensor 161d, the defocus amount in step S304a, and the current lens information in step S304b. Then, according to the auxiliary light type information in step S304c, the area is excluded from the AF sensor area, and the AF sensor area is specified. In each focus detection area in the imaging screen 50 of the imaging optical system, the area included in the AF sensor area is set according to the imaging distance, the irradiation range of the auxiliary light, and the like. Therefore, the camera control unit 170 determines the shooting distance of the subject and each focus detection area included in the subject from the accumulation condition of the line sensor 161d, the defocus amount from step S304a to S304c, lens information, and auxiliary light type information. The luminance and the irradiation distance of the auxiliary light are specified, the auxiliary light does not reach and a high luminance area is extracted and excluded from the AF sensor region.

  Next, in step S305a, it is determined whether a condition for lighting the AF auxiliary light source 140 is satisfied. The lighting condition of the AF auxiliary light source 140 is, for example, that the AF auxiliary light source 140 is turned on when the brightness of each focus detection area is less than a predetermined value, and the AF auxiliary light source 140 is turned on when the brightness of each focus detection area is greater than or equal to a predetermined value. Suppose that it does not light up. The AF-CCD control unit 162 transmits the luminance information of each focus detection area to the camera control unit 170, and the camera control unit 170 uses the luminance information read from the AF-CCD control unit 162 based on the illumination condition. It is determined whether or not the AF auxiliary light source 140 is turned on.

  In step S305a of this example, it is determined whether or not the AF auxiliary light source 140 is turned on based on the accumulation condition of the AF-CCD control unit 162. However, based on the luminance detected by the photometric sensor 137, AF is determined. It may be determined whether or not the auxiliary light source 140 is turned on. Further, the AF-CCD control unit 162 may determine whether to turn on the AF auxiliary light source 140 based on the illumination condition.

  When the camera control unit 170 determines that the AF auxiliary light source 140 is not turned on, the process proceeds to step S306 (see FIG. 8), and when the camera control unit 170 determines that the AF auxiliary light source 140 is turned on, the process proceeds to step S305b.

  In step S305b, the AF auxiliary light source 140 is turned on, and accumulation control by the AF-CCD control unit 162 is performed in step S305c. The accumulation control in step S305c is the same as the accumulation control in step S302, but the area to be controlled is different.

That is, in the accumulation control in step S302, since the position of the area for focusing is not determined, the AF-CCD control unit 162 detects all the focal points corresponding to each of the pair of line sensors 161d _{1 to} 161d _11. the area identified as area sensors for focusing, according to the luminance of the image signal in the AF sensor area corresponding to the line sensors 161d ₁ ~161d _11, accumulation condition of the gain and the accumulation time of the line sensor 161d To control. On the other hand, in the accumulation control in step S305c, since the position of the area for focusing (AF sensor area) is determined by the control process in step S304c, the AF-CCD control unit 162 is specified in step S304c. The accumulation conditions such as the gain and accumulation time of the line sensor 161d are controlled in accordance with the brightness of the image signal in the AF sensor area corresponding to the line sensor 161d in the AF sensor area. When the accumulation control process in step S305c ends, the process proceeds to step S306.

Returning to FIG. 8, if the AF auxiliary light source 140 is not turned on in step S306, all focus detection area regions corresponding to the respective pair of line sensors 161d _{1 to} 161d ₁₁ are used as AF sensor regions. When the defocus amount calculation process for calculating the defocus amount is performed and the AF auxiliary light source 140 is turned on, the defocus amount calculation process for calculating the defocus amount of the AF sensor area specified in step S305c is performed. The calculation method of the defocus amount is the same as that in step S106, and therefore will be omitted.

  Note that, when the AF auxiliary light source 140 is not turned on, the defocus amount calculation process in step S306 is a subsequent step by omitting the defocus amount calculation process in step S306 and using the defocus amount calculated in step S304a. Auto focus processing may be performed.

  In subsequent step S307, the camera control unit 170 determines whether or not the defocus amount has been calculated for all focus detection areas belonging to the AF sensor area. If it is determined that the defocus amount has been calculated for all focus detection areas belonging to the AF sensor area, the process proceeds to step S308. On the other hand, the defocus amount has not been calculated for all focus detection areas belonging to the AF sensor area. When it is determined that the defocus amount is calculated for all focus detection areas belonging to the AF sensor area, the defocus amount calculation is repeated.

  As described above, in this example, before the AF auxiliary light source 104 is turned on, the defocus amount of each focus detection area set in the photographing screen 50 is calculated, and is outside the irradiation range of the AF auxiliary light source 104. The focus detection area that is the luminance is excluded, and the accumulation condition of the line sensor 161d is controlled based on the luminance of the excluded area. That is, the excluded area is an area including a point light source for night scenes, a background light source, and the like. Even when the AF auxiliary light source 140 is turned on, it is difficult for light from the AF auxiliary light source 140 to reach the area. This is an area where there is little change in luminance before and after the light source 140 is turned on. Therefore, as in this example, the area is excluded and the accumulation condition of the line sensor 161d when the AF auxiliary light source 140 is turned on is controlled to perform accumulation control on the area including the subject in this example. .

  Thus, for example, when there is a bright subject such as a light source in the background, the accumulation control of the line sensor 161d is performed in an area excluding the subject and the autofocus process is performed. The accumulation control of the line sensor 161d is performed in correspondence with the subject, and the focus can be adjusted appropriately.

  Further, in this example, the irradiation distance of the auxiliary light is specified based on the auxiliary light type information, the focus detection area that is outside the irradiation range of the AF auxiliary light source 104 and has high luminance is excluded from the AF sensor area, and the AF sensor area The accumulation condition of the line sensor 161d is controlled on the basis of the luminance.

  As a result, the irradiation range of the auxiliary light can be specified according to the irradiation capability of the auxiliary light, and therefore, according to the type of the auxiliary light, an area outside the irradiation range and having a high luminance is excluded, and includes a light source and the like. The accumulation control of the line sensor 161d can be performed in correspondence with the original subject without being pulled by the background.

  The embodiment described above is described for facilitating the understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Camera 100 ... Camera body 110 ... Image pick-up element 111 ... Shutter 120 ... Mirror system 121 ... Quick return mirror 122 ... Sub mirror 123 ... Rotating shaft 131 ... Focus plate 132 ... Transmission type liquid crystal display 133 ... Pentarhythm 134 ... Eyepiece lens 135 Finder 136 Lens 137 Photometric sensor 140 AF auxiliary light source 150 Operation unit 161 Focus detection module 161d Line sensor 162 AF-CCD control unit 163 Defocus calculation unit 164 Lens drive amount calculation unit 165 Lens Drive control unit 170 ... Camera control unit 200 ... Lens barrel 211 ... Lens 212 ... Focus lens 213 ... Lens 220 ... Aperture 230 ... Lens drive motor 240 ... Aperture drive unit 250 ... Lens control unit 260 ... Encoder 50 ... Imaging Surface

Claims (6)

A light receiving means for receiving a light beam corresponding to a plurality of focus detection positions set for a plurality of positions in an image plane by an optical system, accumulating charges, and outputting a light reception signal;
Irradiating means for irradiating a light beam to a target corresponding to the plurality of focus detection positions;
A first photometric value obtained by measuring a light beam obtained corresponding to each of the plurality of focus detection positions in a state where the light beam is not irradiated by the irradiation unit, and the plurality of focal points in a state where the light beam is irradiated by the irradiation unit. Photometric means for obtaining a second photometric value obtained by measuring a light flux obtained corresponding to each of the detection positions;
Of the plurality of focus detection positions, corresponding to a second focus detection position excluding the first focus detection position at which a photometric value equal to or greater than a predetermined value is obtained for both the first photometric value and the second photometric value. Accumulation control means for controlling accumulation of the light receiving means according to accumulation conditions based on the received light signal;
A focus detection apparatus comprising: focus detection means for detecting a focus state of the optical system based on the light reception signal corresponding to the second focus detection position. The focus detection apparatus according to claim 1,
The accumulation control means determines the accumulation condition based on the light reception signal corresponding to a focus detection position selected based on the focus state and the second photometric value. The focus detection apparatus according to claim 2,
The accumulation control unit corresponds to a focus detection position excluding a focus detection position in which the focus state detected by the focus detection unit corresponds to a predetermined shooting distance in a state where the light beam from the irradiation unit is not irradiated. A focus detection apparatus that controls accumulation of the light receiving means according to the accumulation condition based on the received light signal. The focus detection apparatus according to claim 3,
The focus detection apparatus, wherein the accumulation control unit determines the predetermined photographing distance according to an irradiation capability of the irradiation unit. In the focus detection apparatus according to any one of claims 1 to 4,
The focus detection means sets at least a part of a plurality of focus detection positions belonging to the second focus detection position as a focus detection position group,
A focus detection apparatus comprising: selection means for selecting any of the plurality of focus states detected for the focus detection position group.   An imaging apparatus comprising the focus detection apparatus according to claim 1.

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