JP5063184B2 - IMAGING DEVICE, LIGHT EMITTING DEVICE, AND IMAGING DEVICE CONTROL METHOD - Google Patents

Description

The present invention relates to an imaging device such as a digital camera having an autofocus (AF) function, a light emitting device that can be attached to and detached from the imaging device, and a method for controlling the imaging device .

  One AF method in an imaging apparatus such as a digital camera is a phase difference detection method. In the phase difference detection method often used in single-lens reflex digital cameras, the light beam from the imaging optical system is sent to a dedicated focus detection unit (that is, provided separately from the image sensor for image recording) by a quick return mirror. Lead. In the focus detection unit, an incident light beam is divided into a plurality of pieces, and a plurality of images formed by the plurality of light beams are photoelectrically converted by a plurality of light receiving element arrays (line sensors). The focus state (defocus amount) of the imaging optical system is calculated based on the phase differences between the plurality of images detected by signals from these line sensors.

Even in a compact digital camera, as disclosed in Patent Documents 1 to 3, a phase difference detection method may be employed. Specifically, a pair or two pairs of light receiving portions are provided for each microlens array arranged two-dimensionally in the pixels of the image pickup device, and the light receiving portions are projected onto the pupil of the image pickup optical system by the microlenses. Then, the phase difference of the image due to a plurality of light beams that have passed through different portions of the pupil of the imaging optical system is detected to obtain the defocus amount of the imaging optical system. In order to obtain a light beam that passes through different parts of the pupil of the imaging optical system, in Patent Documents 1 and 3, an aperture stop that is offset with respect to the light receiving part behind the microlens is arranged. Moreover, in patent document 2, the microlens and the light-receiving part are shifted mutually.
JP-A-1-216306 JP-A-4-267211 JP 2000-156823 A

  However, in the phase difference detection method using the image sensor, when the pixel itself becomes small due to the increase in the number of pixels of the image sensor, the light beam incident on the microlens from an oblique direction cannot reach the light-shielding diaphragm arranged in front of the image sensor. That is, if the defocus amount is large, much of the light beam is lost. For this reason, the defocus range that can be detected is limited to a small size, and a defocus detection capability equivalent to that when a dedicated AF sensor is used cannot be obtained.

  Therefore, when performing macro imaging in which a large defocus amount is generated or when using a telephoto lens having a long focal length, it is preferable to use a phase difference detection method using a dedicated focus detection unit. Therefore, an imaging apparatus that can selectively use the AF function in the phase difference detection method using a dedicated focus detection unit and the AF function in the phase difference detection method using an image sensor can be considered.

  On the other hand, the detection wavelength region of the photodiode used in the image sensor has sensitivity up to about 300 nm to 1000 nm. However, in order to match the visibility characteristics of human eyes, components on the longer wavelength side than the wavelength of about 650 nm are blocked by an infrared cut filter as an optical filter.

  FIG. 15 shows spectral sensitivity characteristics of a general image sensor and spectral sensitivity characteristics of an infrared cut filter arranged in front of the image sensor.

  In the figure, the horizontal axis represents wavelength, and the vertical axis represents relative sensitivity. A indicates the spectral sensitivity characteristics of the photodiode used in the image sensor. Further, B indicates the spectral sensitivity characteristic of the infrared cut filter.

  Further, in the phase difference detection method, when imaging in a dark place or when imaging a subject with low contrast, it is widely performed to irradiate the subject with auxiliary light to enable focus detection. The light source of the auxiliary light is built in the imaging device or provided in a flash device that can be attached to and detached from the imaging device.

  As an auxiliary light source, an LED having a light emission wavelength in the near infrared region is generally used so that a person who is a subject does not feel dazzling. The emission spectrum characteristic of the LED is indicated by C in FIG.

  As can be seen from the comparison between B and C in FIG. 15, the auxiliary light in the near infrared region is cut by the infrared cut filter and hardly reaches the imaging device. For this reason, when performing phase difference detection AF using an image sensor, even if the subject is irradiated with light in the near infrared region as auxiliary light, malfunction may occur or focus detection may not be performed.

  The present invention provides an imaging apparatus capable of irradiating a subject with auxiliary light that matches a wavelength region of light used in focus detection and performing accurate focus state detection (focus detection).

An image pickup apparatus according to one aspect of the present invention includes an image pickup device that outputs a signal for generating a recording image by photoelectrically converting a subject image formed by an image pickup optical system, and the image pickup optical system to the image pickup device. In an imaging mode in which light of the imaging optical system is incident on a light receiving sensor different from the imaging element, and a filter that blocks components in the infrared wavelength region of the light that travels from the imaging optical system using the light receiving sensor In the imaging mode in which the light of the imaging optical system is incident on the imaging element, the imaging optical using the imaging element in the first focus detection unit that detects the phase difference of the plurality of images formed by the light of A second focus detection unit that detects a phase difference between a plurality of images formed by light from the system, and a light-receiving element of the first focus detection unit when detecting a focus state by the first focus detection unit. Feeling Visible light wavelength region corresponding to the sensitivity characteristic of the image sensor when the first light emitting unit that emits light in the infrared wavelength region corresponding to the characteristic emits light and the second focus detection unit detects the focus state And a light emission control means for causing the second light emission means for emitting the light to emit light.

Note that a light-emitting device that is attachable to and detachable from the imaging device and includes the first light-emitting means and the second light-emitting means also constitutes another aspect of the present invention.

Further, according to another aspect of the present invention, there is provided a control method for an image pickup apparatus, an image pickup device that outputs a signal for generating a recording image by photoelectrically converting a subject image formed by an image pickup optical system; In the imaging mode in which light from the imaging optical system is incident on a light receiving sensor that is different from the filter, and a filter that blocks components in the infrared wavelength region of light traveling from the system toward the imaging device, the light receiving sensor is used. In the imaging mode in which the light of the imaging optical system is incident on the imaging element, a first focus detection unit that detects a phase difference between a plurality of images formed by light from the imaging optical system, and the imaging element And a second focus detection unit that detects a phase difference between a plurality of images formed by light from the imaging optical system using the imaging device, the control method of the imaging device, the first focus detection unit A first light emission control step of causing the first light emitting means to emit light in the infrared wavelength region corresponding to the sensitivity characteristic of the light receiving element of the first focus detecting means to detect the point state; A second light emission control step of causing the second light emitting means to emit light in the visible light wavelength region corresponding to the sensitivity characteristic of the image sensor when the focus state is detected by the two focus detection means. Features.

  According to the present invention, when the detection operation is performed by the first focus detection unit, accurate focus detection can be performed using the auxiliary light in the first wavelength region. Further, when the detection operation is performed by the second focus detection unit, the auxiliary light in the second wavelength region is used while avoiding unnecessary emission of auxiliary light in the first wavelength region that is not used for the detection operation. Accurate focus detection can be performed.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a configuration of an image pickup system including a single-lens reflex digital camera as an image pickup apparatus that is an embodiment of the present invention, a flash apparatus that is a light emitting apparatus, and an interchangeable lens.

  In FIG. 1, reference numeral 100 denotes a single-lens reflex digital camera (hereinafter referred to as a camera), and reference numeral 200 denotes an interchangeable lens that can be attached to and detached from the camera 100. Reference numeral 400 denotes a flash device as a light emitting device that can be attached to and detached from the camera 100.

  In the camera 100, reference numeral 1 denotes a main mirror, which is disposed obliquely in an optical path (imaging optical path) from an imaging optical system (to be described later) in the viewfinder observation state (hereinafter, this position is referred to as a down position). Retreat to the outside (hereinafter, this position is referred to as the up position). The main mirror 1 is constituted by a half mirror. At the down position, a part of the light beam from the imaging optical system is reflected and guided to a finder optical system to be described later, and the other light beam is transmitted.

  The viewfinder optical system is configured as follows. Reference numeral 2 denotes a focusing plate, which forms an image by a light beam from the imaging optical system. 4 is a pentaprism and 5 is an eyepiece. The light beam from the focus plate 2 is reflected by the pentaprism 4 and guided to the eye of the photographer through the eyepiece 5. The imager can observe the subject within the imaging range by observing the focus plate 2 through the eyepiece 5.

  Such a mode in which the subject can be observed through the finder optical system is hereinafter referred to as an optical finder (OVF) mode.

  Reference numeral 3 denotes a sub mirror, which is arranged obliquely in the imaging optical path with the main mirror 1 in the finder observation state, and retracts out of the imaging optical path in the imaging state. In the finder observation state, the light beam transmitted through the main mirror 1 is reflected by the sub mirror 3 and guided to the focus detection unit 8. The focus detection unit 8 is a dedicated unit for performing focus detection by the phase difference detection method and focus control based on the focus detection result.

  The focus detection unit 8 includes a secondary imaging lens 8a having a pair or a plurality of pairs of lens units, and a pair or a plurality of pairs as a light receiving sensor that photoelectrically converts a pair or a plurality of pairs of images formed by the lens units. Line sensor 8b. The line sensor 8b emits light in a wavelength region indicated by A in FIG. 15, that is, a visible wavelength region indicated by B in the same figure, a near infrared wavelength region indicated by C in the same figure, and an infrared wavelength region longer than this. Sensitivity to.

  The infrared wavelength region (including the near infrared wavelength region) corresponds to the first wavelength region, and the visible wavelength region corresponds to the second wavelength region.

  Reference numerals 6 and 7 respectively denote an imaging lens and a photometric sensor for taking a part of the light flux from the finder optical system and measuring the subject brightness. Since the photometric sensor 7 has a logarithmic compression circuit therein, the output from the photometric sensor 7 is logarithmically compressed.

  Reference numeral 9 denotes a focal plane shutter for controlling the exposure amount of the image sensor described later.

  Reference numeral 14 denotes an image sensor composed of a CCD sensor, a CMOS sensor, or the like. On the front surface of the image sensor 14 (between the image sensor 14 and the shutter 9), the red component that blocks light in the infrared wavelength region and transmits light in the visible wavelength region out of the light traveling from the image pickup optical system to the image sensor 14. An outer cut filter 19 is disposed. As a result, the imaging device 14 is sensitive to light in the visible wavelength region indicated by B in FIG. 15, but is sensitive to light in the infrared wavelength region on the longer wavelength side than C in FIG. Will not have.

  Reference numeral 16 denotes an A / D converter that converts an analog imaging signal from the imaging element 14 into a digital signal.

 A timing generation circuit 18 supplies a clock signal to the image sensor 14, the A / D converter 16, and the D / A converter 26. The timing generation circuit 18 is controlled by the memory control circuit 22 and a system controller 50 described later.

 An image processing circuit 20 performs various image processing such as pixel interpolation processing, color conversion processing, and AWB (auto white balance) processing on the digital image pickup signal from the A / D converter 16 or the memory control circuit 22. . Thereby, an image signal is generated.

  The memory control circuit 22 controls the A / D converter 16, the timing generation circuit 18, the image processing circuit 20, the image display memory 24, the D / A converter 26, the memory 30, and the compression / decompression circuit 32.

  The image signal from the image processing circuit 20 or the digital image pickup signal from the A / D converter 16 is written into the image display memory 24 or the memory 30 via the memory control circuit 22.

 Reference numeral 28 denotes an image display unit composed of an LCD or the like. The display image data written in the image display memory 24 is sent to the image display unit 28 via the D / A converter 26.

  Display image data generated by the image processing circuit 20 and written in the image display memory 24 is displayed on the image display unit 28 with the main mirror 1 and the sub mirror 3 retracted to the up position and the shutter 9 is opened. Thus, the electronic finder function is realized. The state in which the subject image can be observed through the electronic viewfinder is referred to as an electronic viewfinder (EVF) mode.

  The memory 30 stores the generated still image and moving image. The memory 30 is also used as a work area for the system controller 50.

 A compression / decompression circuit 32 compresses / decompresses image data by adaptive discrete cosine transform (ADCT) or the like, reads an image stored in the memory 30, performs compression processing or decompression processing, and stores the processed data again in the memory. Write to 30.

  Reference numeral 40 denotes a shutter control circuit that controls the shutter 9, and reference numeral 41 denotes a mirror control circuit that moves the main mirror 1 up and down, each of which includes a motor and its drive circuit.

  The system controller 50 controls the overall operation of the camera 100. Further, the system controller 50 performs a detection process for detecting a phase difference between images (image signals) formed on the pair or plural pairs of line sensors 8b of the focus detection unit 8, and based on the phase difference, the system controller 50 detects the phase difference of the imaging optical system. The focus amount (focus state) is calculated. Then, a drive amount for obtaining the focus of a focusing lens described later is calculated from the defocus amount. The AF method for obtaining the defocus amount and the focus lens drive amount using the focus detection unit 8 in this manner is hereinafter referred to as detection unit phase difference AF.

  Further, the system controller 50 performs a detection process for detecting a phase difference of an image formed on an AF pixel (which will be described later) provided in the image sensor 14 and defocuses the imaging optical system from the phase difference. Calculate the quantity. Then, a drive amount for obtaining the focusing lens focus is calculated from the defocus amount. The AF method for obtaining the defocus amount and the focus lens drive amount using the image sensor 14 in this way is hereinafter referred to as image sensor phase difference AF.

  Further, the system controller 50, which is an example of the light emission control unit and the exposure control unit, controls the light emission of the auxiliary light in the flash device 400 and controls the light emission of the illumination light during the imaging operation.

  A memory 52 stores data such as constants, variables, and computer programs for operating the system controller 50.

  An information output unit 54 outputs information indicating the operating state of the camera 100, a message, and the like using characters, images, sounds, and the like. The information output unit 54 includes a liquid crystal display element, a speaker, and the like. The information output unit 54 displays a part of information on the finder screen via the finder optical system.

  Reference numeral 56 denotes an electrically erasable / recordable nonvolatile memory such as an EEPROM.

  Reference numeral 60 denotes a mode dial switch, which is operated to switch and set each function such as power ON / OFF, imaging mode (still image imaging mode or moving image imaging mode), and reproduction mode.

  An imaging preparation switch (SW1) 62 is turned on by a first stroke operation (half-press) of a shutter button (not shown), and starts imaging preparation operations such as photometry (AE processing) and AF processing.

 Reference numeral 64 denotes an imaging switch (SW2), which is turned on by a second stroke operation (full press) of the shutter button, and starts an imaging operation. Here, the imaging operation includes the up operation of the main mirror 1 and the sub mirror 3, the opening / closing operation of the shutter 9, the operation of generating an image signal in the image processing circuit 20 based on the imaging signal from the imaging device 14, and the image signal in the memory The operation includes writing to the memory 30 via the control circuit 22. Also included is an operation of reading the image data from the memory 30, compressing it by the compression / decompression circuit 32, and recording it on the recording medium 120. These series of imaging operations can also be referred to as recording image acquisition operations. Hereinafter, the time when the recording image is acquired is referred to as an imaging operation. The recording medium 120 is configured by a semiconductor memory, an optical disk, or the like.

 Reference numeral 66 denotes a finder mode setting switch, which is operated to select an OVF mode or an EVF mode. When the EVF mode is selected, the main mirror 1 and the sub mirror 3 are retracted from the imaging optical path, and the shutter 9 is opened. Then, a moving image generated using the image sensor 14 is displayed on the image display unit 28.

  A quick review ON / OFF switch 68 is operated to select whether or not to display the acquired recording image on the image display unit 28 for a predetermined time.

 Reference numeral 70 denotes an operation unit including various buttons, a touch panel, and the like, and is operated to display a menu screen for selecting functions and various settings of the camera 100 and determining menu items.

 Reference numeral 80 denotes a power supply control circuit, which includes a battery detection circuit that detects the remaining battery level, a DC-DC converter that converts a power supply voltage from the battery into a predetermined operating voltage, a switch circuit that switches a block to be energized, and the like.

  A battery 86 is a primary battery such as an alkaline battery or a lithium battery, or a secondary battery such as a NiMH battery or a Li battery. Reference numerals 82 and 84 denote connectors for electrical connection between the battery 86 and the camera 100.

 Reference numeral 90 denotes an interface for performing communication with the recording medium 120, and 92 denotes a connector connected to the recording medium 120. A recording medium attachment / detachment detector 98 detects whether or not the recording medium 120 is attached to the connector 92.

  A communication unit 72 has communication functions such as RS232C, USB, IEEE1394, and wireless communication.

  Reference numeral 73 denotes a connector for connecting another device to the camera 100 via the communication unit 72. When performing wireless communication, an antenna is connected.

  The recording medium 120 includes an interface 124 for performing communication with the camera 100 and a connector 126 for performing electrical connection with the camera 100. In the recording unit 122, compressed image data output from the camera 100 is written.

  399 is a communication line for performing communication between the interchangeable lens 200 and the system controller 50, and 499 is a communication line for performing communication between the flash device 400 and the system controller 50.

  In the interchangeable lens 200, 201 is a focusing lens that moves in the optical axis direction to perform focus adjustment, and 202 is a focus drive actuator that drives the focusing lens 201 in the optical axis direction. A focus control circuit 211 controls the focus driving actuator 202 based on a command from the lens control microcomputer 206.

  Reference numeral 207 denotes a zooming lens that moves in the optical axis direction and performs zooming. Reference numeral 208 denotes a zoom drive actuator that drives the zooming lens 207 in the optical axis direction. A zoom control circuit 212 controls the zoom drive actuator 208.

  Reference numeral 203 denotes an encoder that detects the positions of the focusing lens 201 and the zooming lens 207 and a subject distance detector that calculates the subject distance based on the output from the encoder.

  A diaphragm 204 adjusts the amount of light reaching the image sensor 14. Reference numeral 250 denotes an aperture drive actuator, and 205 denotes an aperture control circuit that controls the aperture drive actuator 250 based on a command from the lens control microcomputer 206.

  The lens control microcomputer 206 controls the focus drive and aperture drive described above and communicates with the system controller 50 of the camera 100. The lens control microcomputer 206 is electrically connected to the camera 100 (system controller 50) via a connector 210. The connector 210 supplies a power supply voltage from the battery 86 into the interchangeable lens 200.

  Next, the flash device 400 will be described with reference to FIG. Reference numeral 401 denotes a light source serving as a second light emitting unit configured by a xenon tube or the like, and converts current energy into light emission energy. In this embodiment, a xenon tube is used as the light source 401. Reference numerals 402 and 403 denote a Fresnel lens and a reflecting plate, respectively, which have a role of efficiently condensing light from the xenon tube 401 toward the subject. The xenon tube 401 of the present embodiment is a light source that irradiates a subject with illumination light during an imaging operation, and is also used as a second light emitting unit that irradiates the subject with AF auxiliary light during AF.

  Reference numerals 448 and 445 denote first and second light receiving elements such as photodiodes provided for monitoring the light emission amount of the xenon tube 401. A part of light emitted from the xenon tube 401 is guided to the first light receiving element 448 via the light guide 406 and the glass fiber 407. In addition, a part of the light emitted from the xenon tube 401 is guided to the second light receiving element 445 through the light guide 406.

  The flash control microcomputer 450 controls the light emission amount of the preliminary light emission and the main light emission of the xenon tube 401 based on the output from the first light receiving element 448. The preliminary light emission is performed in order to determine the light emission amount in the main light emission that emits the flash light that illuminates the subject during the imaging operation. In addition, the flash control microcomputer 450 performs flat light emission control for causing the xenon tube 401 to emit light continuously at a predetermined light emission amount for a predetermined time based on an output from the second light receiving element 445.

  Reference numeral 409 denotes a near-infrared light-emitting diode as a first light-emitting unit serving as a light source of AF auxiliary light irradiated to the subject. The light emission operation of the near infrared light emitting diode 409 is controlled by the flash control microcomputer 450. The AF auxiliary light emitted from the near-infrared light emitting diode 409 is light in the near-infrared wavelength region (region indicated by C in FIG. 15) as the first wavelength region.

  Reference numeral 410 denotes a pattern master disposed on the front surface of the near-infrared light emitting diode 409 in order to project a striped pattern image onto the subject by AF auxiliary light during the AF operation. Reference numeral 411 denotes a projection lens that projects the AF auxiliary light that has passed through the pattern original 410 toward the subject.

  FIG. 3 shows a pattern image projected onto the subject by AF auxiliary light. D is an imaging range where a subject exists, and E is a pattern image projected onto a part of the imaging range D.

  A contact group 420 serves as a communication interface between the camera 100 (system controller 50) and the flash control microcomputer 450.

  FIG. 4 shows an electrical configuration of the flash device 400 connected to the camera 100 via the contact group 420. The components shown in FIG. 3 are given the same reference numerals as in FIG.

  Reference numeral 421 denotes a battery. A DC-DC converter 422 boosts the voltage from the battery 421 to several hundred volts.

  Reference numeral 423 denotes a main capacitor for accumulating electric energy. Reference numerals 424 and 425 denote resistors, which divide the voltage of the main capacitor 423 into a predetermined ratio.

  Reference numeral 426 denotes a coil for limiting an energization current to the xenon tube 401, and reference numeral 427 denotes a diode for absorbing a counter electromotive voltage generated when the xenon tube 401 stops emitting light. Reference numeral 431 denotes a trigger generation circuit for generating a trigger signal for starting discharge in the xenon tube 401, and reference numeral 432 denotes a light emission control circuit such as an IGBT.

  A data selector 440 selects data ports D0, D1, and D2 according to a combination of inputs to the input ports Y0 and Y1, and outputs a signal from the selected data port to the port Y.

  A comparator 441 controls the light emission level of flat light emission, and its output data is input to the data port D2. Reference numeral 442 denotes a comparator for controlling the amount of flash emission, and its output data is input to the data port D1.

  Reference numeral 444 denotes a photometric circuit that amplifies a minute current flowing through the second light receiving element 445 and converts the photocurrent into a voltage, and its output is input to the comparator 441.

  Reference numeral 446 denotes an integral photometry circuit that logarithmically compresses the photocurrent flowing through the first light receiving element 448 and compresses and integrates the light emission amount of the xenon tube 401. The output of the integral photometry circuit 446 is input to the comparator 442.

  The operation of each of the above units in the flash device 400 is controlled by the flash control microcomputer 450.

  Reference numeral 451 denotes a transistor for turning on / off the energization of the near-infrared light emitting diode 409, and reference numeral 452 denotes a resistor for limiting the current flowing through the light emitting diode 409. Reference numeral 453 denotes a resistor for limiting the base current of the transistor 451.

  The operation of each of the above units in the flash device 400 is controlled by the flash control microcomputer 450.

  Next, the port (terminal) of the flash control microcomputer 450 will be described. CNT is a control output port for controlling the charging of the DC / DC converter 422, and CLK is an input port for a synchronous clock signal for serial communication with the camera 100. DO is a serial output port for transferring serial data from the flash control microcomputer 450 to the system controller 50 in synchronization with the synchronous clock. DI is a serial data input port for transferring serial data from the system controller 50 to the flash control microcomputer 450 in synchronization with the synchronous clock.

  INT is a control signal output port for controlling the integration operation of the integral photometry circuit 446, and AD0 is an A / D input port for reading an integral voltage indicating the light emission amount of the integral photometry circuit 446. DA0 is a D / A output port for outputting the comparator voltage of the comparators 441 and 442.

  Y0 and Y1 are output ports to the data selector 430 described above, and TRIG is a trigger port that outputs a signal that causes the trigger generation circuit 431 to generate a trigger signal. AUX is a lighting port for controlling the auxiliary light lighting transistor 451.

  FIG. 5 shows a part of the light receiving surface of the image sensor 14. A Bayer array color filter is regularly arranged in front of each pixel of the image sensor 14. G represents a green color filter, R represents a red color filter, and B represents a blue color filter. In addition, AF pixels SA and SB are arranged for each predetermined pixel in the horizontal direction and the vertical direction on the light receiving surface.

  FIG. 6 shows the structure of the AF pixel SA. FIG. 7 shows the structure of the AF pixel SB. In these figures, the upper figure is a view of the AF pixel as viewed from above, and the lower figure shows a b-b 'cross section of the AF pixel. The AF pixel does not have a filter layer, and the microlens 301 is disposed on the top. A flat layer 302 forms a plane on which the microlens 301 is mounted.

  In the AF pixel, a light-shielding layer (light-shielding stop) having openings 303a and 303b that are offset (offset) from the center (pixel center) of the photoelectric conversion area of the AF pixel on the same plane as the light-shielding metal for preventing color mixing. 303. The light shielding layer 303 is formed of an aluminum wiring layer. Reference numeral 304 denotes a photoelectric conversion layer.

  Here, the opening 303a of the light shielding layer 303 on the AF pixel SA side and the opening 303b of the light shielding layer 303 on the AF pixel SB side are offset to the opposite sides with respect to the pixel center. As a result, light beams that have passed through different portions of the pupil of the imaging optical system are incident on the AF pixel SA and the AF pixel SB. Reference numeral 304 denotes a photoelectric conversion layer.

  An AF operation performed using AF pixels will be described with reference to FIG. In the figure, 310 is a schematic diagram of the imaging optical system, 311 is an AF pixel SA, and 312 is an AF pixel SB. In the AF pixel SA, only L1 to L3 and the light beam therebetween enter the photoelectric conversion unit 304 through the opening 303a offset to the right side of the light-shielding stop 303. That is, only the light beam on the right side of the optical axis AXL of the imaging optical system 310 is incident on the AF pixel SA.

  On the other hand, in the AF pixel 312, only L 4 to L 6 and the light beam therebetween enter the photoelectric conversion unit 304 through the opening 303 b offset to the left side of the light-shielding stop 303. That is, only the light beam on the left side of the optical axis AXL of the imaging optical system 310 is incident on the AF pixel SB.

  Hereinafter, the distance between the centroid of the light beam incident on the AF pixel SA and the centroid of the light beam incident on the AF pixel SB is L.

  The state of image formation when a large number of such AF pixels SA and SB are arranged will be described with reference to FIGS. 9A to 9B.

  FIG. 9A shows a state where the focusing lens 201 is located closer to the subject than the in-focus position, that is, a front pin state. FIG. 9B shows an in-focus state in which the focusing lens 201 is located at the in-focus position. FIG. 9C shows a state where the focusing lens 201 is positioned on the image plane side with respect to the in-focus position, that is, a rear pin state.

  In the front pin state of FIG. 9A, the position on the image sensor 14 between the position of the image (A image) formed on the AF pixel SA and the position of the image (B image) formed on the AF pixel SB is shown. The difference L is a negative value, and the difference L is 0 in the in-focus state of FIG. 9B. In the rear pin state of FIG. 9C, the difference L is a positive value. Therefore, by detecting the distance between the A image formed on the AF pixel SA and the B image formed on the AF pixel SB, the focus state such as the front pin state, the focused state, and the rear pin state is detected. Can do.

  A plurality of actual AF pixels SA and SB are discretely arranged on the image sensor 14 as shown in FIG. For this reason, the A image is read out as an image signal by connecting signals from the plurality of AF pixels SA, and the B image is read out as an image signal by connecting signals from the plurality of AF pixels SB.

  Next, the operation of the imaging system of the present embodiment will be described with reference to FIGS. First, FIGS. 10 and 11 show flowcharts of a main routine executed by the system controller 50 mounted on the camera 100 in accordance with a computer program. “S” indicates a step. In addition, parts having the same circled character indicate that they are connected to each other.

  When the mode dial switch 60 in the camera 100 is turned on (ON), the system controller 50 initializes flags, control variables, and the like (S101).

  Next, the setting position of the mode dial switch 60 is determined (S102), and when the mode dial switch 60 is set to power OFF, the operations of the image display unit 28 and the information output unit 54 are terminated. At this time, parameters such as flags and control variables, setting values, and setting modes are recorded in the nonvolatile memory 56. Then, the power control circuit 80 performs predetermined end processing such as shutting off unnecessary power of each part of the camera 100 including the image display unit 28 (S103). Thereafter, the process returns to S102.

  In S102, when the mode dial switch 60 is set to an imaging mode such as a still image imaging mode, the process proceeds to S104.

  In S <b> 104, the remaining capacity of the battery 86 is determined through the power control circuit 80. When the remaining capacity is less than the predetermined level, the information output unit 54 is used to give a warning by display or sound (S106), and the process returns to S102. If the remaining capacity of the battery 86 is equal to or higher than a predetermined level, the free capacity of the recording medium 120 is determined (S105). When the free space is less than the predetermined level, the information output unit 54 is used to give a warning by display or voice (S106), and the process returns to S102. When the free capacity of the recording medium 120 is equal to or higher than the predetermined level, various setting states of the camera 100 are displayed on the information output unit 54 (S107).

  Subsequently, the system controller 50 determines the setting state of the finder mode setting switch 66 (S108), and proceeds to step 120 if the OVF mode is set. When the EVF mode is set, the main mirror 1 and the sub mirror 3 are moved up (S111), the shutter 9 is opened (S112), and the image signal is sent to the image processing circuit 20 based on the image pickup signal from the image pickup device 14. Generate. Then, the image signal written in the image display memory 24 via the memory control circuit 22 is displayed on the image display unit 28 (S113). Thereby, so-called live view display (moving image display) is performed, and the subject can be observed by the electronic viewfinder.

  Next, the system controller 50 determines the state of the imaging preparation switch (SW1) 62 (S120), and returns to S102 if SW1 is OFF. If SW1 is ON, photometry (AE) processing is performed to determine the aperture value and shutter speed (S121). Also, AF processing is performed to detect the focus of the imaging optical system and drive the focusing lens 201 based on the result (S121). Details of photometry / AF processing (S121) will be described later.

  When the photometry / AF processing is completed, the system controller 50 determines the state of the imaging switch (SW2) 64 (S122). If SW2 is OFF, the process returns to S102. The imaging process is executed (S123). Details of the imaging process will be described later.

  After completion of the imaging process, the system controller 50 again determines the state of SW2 (S124), and if SW2 is OFF, displays the recording image acquired this time on the image display unit 28 (S126). This is called quick review display. Then, after displaying the recording image for a predetermined time (review time) (S127), the process returns to step 102 and a series of processing is repeated.

  On the other hand, if SW2 is ON in S124, the system controller 50 determines whether or not the continuous shooting mode is set (S125), and returns to S121 in the continuous shooting mode. If the continuous shooting mode is not selected, the process returns to S124.

  Next, the photometry process in the photometry / AF process in S122 of FIG. 11 will be described with reference to FIG.

  In step S <b> 221, the system controller 50 determines the finder mode selected by the finder mode setting switch 66. When the OVF mode is set, the subject luminance is measured using the photometric sensor 7 (S222), and the exposure amount in the imaging process is calculated (S223).

  On the other hand, when the finder mode is the EVF mode (S221), the system controller 50 reads an image generated based on a signal from the image sensor 14 (S230). Next, the image processing circuit 20 divides the entire image into a predetermined number, and calculates a luminance value in each divided area from the image signal (S231).

  Next, it is determined whether or not the luminance value obtained in S231 indicates an appropriate exposure state (S232). If not appropriate, the charge accumulation time of the image sensor 14 (in electronic shutter speed) is changed, and the aperture value of the aperture 204 is changed so that the image displayed on the electronic viewfinder has an appropriate brightness. Control is performed (S233). On the other hand, if the luminance value obtained in S231 is appropriate, the exposure amount (aperture value and shutter speed) during the imaging operation is calculated based on the ISO sensitivity (S234).

  Further, the system controller 50 determines whether the white balance is appropriate from the image signal (S235). If it is not appropriate, white balance calculation is performed to control the gain of each RGB color so as to achieve an appropriate white balance (S236). On the other hand, if it is appropriate, the process returns to S230.

  Next, the AF process will be described with reference to FIG. In S301, the system controller 50 determines the setting of the finder mode setting switch 66. When the OVF mode is set, charge accumulation of the line sensor 8b in the focus detection unit 8 is performed (S302).

  If the required image signal level cannot be obtained despite charge accumulation for a predetermined time, specifically, if the subject brightness (S303) or the subject contrast (S304) is low, focus detection is impossible. An infrared auxiliary light lighting command is output (S305). The lighting command is transmitted to the flash control microcomputer 450.

  Upon receiving the auxiliary light emission command, the flash control microcomputer 450 sets the AUX (lighting) port shown in FIG. 4 to a high level and turns on the transistor 451. Thereby, the near-infrared light emitting diode 409 is turned on, and the pattern image of the near-infrared auxiliary light (auxiliary light in the first wavelength region) shown in FIG. 3 is projected onto the subject (S305). Then, returning to S302, the charge accumulation of the line sensor 8b is performed again.

  If the subject brightness and the contrast are both appropriate in S303 and S304, the phase difference between the image signals from the pair or plural pairs of line sensors 8b is detected, and the defocus amount is calculated based on the phase difference (S306). ).

  Next, it is determined whether or not the defocus amount is within a predetermined range (S307). If the defocus amount is outside the predetermined range, a drive amount for obtaining the in-focus state of the focusing lens 201 is calculated based on the defocus amount. Then, a drive command including the drive amount information is transmitted to the interchangeable lens 200 (S308).

  Upon receiving the drive command, the lens control microcomputer 206 drives the focus drive actuator 202 according to the drive amount via the focus control circuit 211. Then, returning to S302, focus detection (S302 to S306) and focus determination (S307) are performed again. If the defocus amount is within the predetermined range (S307), the AF process is terminated. In this way, a focused state by the detection unit phase difference AF is obtained.

  If the EVF mode is set by the finder mode setting switch 66 in S301, the system controller 50 uses a plurality of AF pixels SA and SB in S312 together with the AE processes in S230 to S236 in FIG. Charge accumulation.

  If the required image signal level cannot be obtained by charge accumulation for a predetermined time, specifically, if the subject brightness (S313) or the subject contrast (S314) is low, it is determined that focus detection is impossible, and visible light assistance is performed. A light lighting command is output (S315). The lighting command is transmitted to the flash control microcomputer 450.

  In step S315, the system controller 50 does not output a near-infrared auxiliary light lighting command. This is because most of the near-infrared auxiliary light is blocked by the infrared cut filter 19 disposed in front of the image sensor 14 and hardly reaches the image sensor 14. That is, light emission by the near-infrared light emitting diode 409 is not performed because power is wasted. For this reason, in this embodiment, light emitted from the xenon tube 401 for a predetermined time is used as visible light auxiliary light (auxiliary light in the second wavelength region). Then, the process returns to S312 while causing the xenon tube 401 to emit light, and charge accumulation is performed again in the AF pixels SA and SB.

  In S313 and S314, when both the subject brightness and the contrast are appropriate, the phase difference between the image signals from the AF pixels SA and SB is detected, and the defocus amount is calculated based on the phase difference (S316).

  Next, it is determined whether or not the defocus amount is within a predetermined range (S317). If the defocus amount is out of the predetermined range, a drive amount for obtaining the in-focus state of the focusing lens 201 is calculated based on the defocus amount. Then, a drive command including the drive amount information is transmitted to the interchangeable lens 200 (S318).

  Upon receiving the drive command, the lens control microcomputer 206 drives the focus drive actuator 202 according to the drive amount via the focus control circuit 211. Then, returning to S312, focus detection (S312 to S316) and focus determination (S317) are performed again. If the defocus amount is within the predetermined range (S317), the AF process is terminated. In this way, a focused state by the image sensor phase difference AF is obtained.

  Next, imaging processing (S123) will be described with reference to FIG. If the OVF mode is set by the finder mode setting switch 66 in S331, the system controller 50 determines whether or not the flash mode is for performing imaging using a flash (S332).

  In the case of the flash mode, the flash device 400 is instructed to perform pre-flash with a predetermined light amount (S333). While the pre-light emission is performed by the xenon tube 401, the luminance of the reflected light from the subject is measured by the photometric sensor 7 (S334), and based on the photometric result, the aperture value calculated in S233 and the ISO sensitivity setting. The amount of emitted light is calculated (S335). Thereafter, the main mirror 1 and the sub mirror 3 are moved up and retracted out of the imaging optical path.

  On the other hand, if the EVF mode is set in S331, the system controller 50 determines whether or not the flash mode is set (S340). In the flash mode, the flash device 400 is instructed to perform pre-flash with a predetermined light amount (S341). While pre-emission is being performed by the xenon tube 401, charge accumulation and signal readout of the image sensor 14 are performed, and the luminance of reflected light from the subject is measured from the generated image, similarly to S230 (S342). Then, based on the photometric result, the aperture value calculated in S234 and the ISO sensitivity setting, the light emission amount in the main light emission is calculated (S343). Thereafter, the shutter 9 is closed (S344).

  Subsequently, in both the OVF mode and the EVF mode, the system controller 50 drives the aperture 204 to the aperture value calculated in S233 or S234 (S345). Thereafter, charge accumulation in the image sensor 14 is started, the shutter 9 is opened, and exposure of the image sensor 14 is started (S346).

  Next, the system controller 50 determines again whether or not the flash mode is set (S347). In the flash mode, the main light emission of the xenon tube 401 is performed at the light emission amount obtained in S335 or S343 in synchronization with the fully opening of the shutter 9 (S348).

  When the predetermined shutter time elapses in this way, the system controller 50 closes the shutter 9 (S349), reads the image signal from the image sensor 14 (S350), and causes the image processing circuit 20 to generate an image (development) (S351). ). Further, the generated image is stored in the memory 30, the image stored in the memory 30 is read by the compression / decompression circuit 32, the compression process or the expansion process is performed, and the processed image data is stored in the recording medium 120. Write. Thereby, an imaging process is complete | finished.

  In the present embodiment, the imaging apparatus capable of selecting the detection unit phase difference AF and the imaging element phase difference AF has been described. However, in the embodiment of the present invention, the detection unit phase difference AF and the so-called contrast AF in which the peak value of the high-frequency component (contrast) of the image generated by using the imaging element can be selected can be selected. Including. Since the contrast changes depending on the imaging state of the subject image on the image sensor, it can be said that the contrast changes depending on the focus state of the imaging optical system. That is, detecting the contrast means detecting the focus of the imaging optical system.

  As described above, according to the present embodiment, auxiliary light that matches the sensitivity characteristics of the light receiving elements (line sensor 8b and imaging element 14 in the focus detection unit 8) used for the focus state detection operation is used. Accordingly, it is possible to perform AF control with high speed and high accuracy while avoiding unnecessary auxiliary light lighting and focusing determination operation.

  In addition, the said Example is only an example and the Example of this invention is not limited to these. Various modifications and variations of each embodiment are possible.

  For example, in the above-described embodiment, the case where the light source for auxiliary light is provided in the flash device that can be attached to and detached from the camera has been described, but the light source for auxiliary light may be incorporated in the camera.

1 is a block diagram illustrating a configuration of an imaging system including a camera and a flash device according to an embodiment of the present invention. The schematic diagram which shows the structure of the flash apparatus of an Example. FIG. 4 is a diagram illustrating an example of an auxiliary light pattern image projected onto a subject from the flash device according to the embodiment. The figure which shows the electric circuit structure of the flash apparatus of an Example. FIG. 3 is a partially enlarged view showing a configuration of an image sensor used in the camera of the embodiment. FIG. 4 is a top view and a side view of an AF pixel provided in the image sensor. FIG. 6 is a top view and a side view of another AF pixel provided in the image sensor. The figure explaining the focus detection principle using AF pixel. The figure explaining the focus detection state (front pin state) using AF pixel. The figure explaining the focus detection state (focusing state) using AF pixel. The figure explaining the focus detection state (rear pin state) using AF pixel. The flowchart which shows the main routine of the process performed with the camera of an Example. The flowchart which shows the main routine of the process performed with the camera of an Example. 6 is a flowchart showing photometric processing performed by the camera of the embodiment. 6 is a flowchart illustrating AF processing performed by the camera of the embodiment. 6 is a flowchart illustrating imaging processing performed by the camera of the embodiment. The figure which shows the spectral sensitivity characteristic of an infrared cut filter and auxiliary light.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Camera 8 Focus detection unit 14 Image pick-up element 20 Image processing circuit 50 System controller 200 Interchangeable lens 201 Focusing lens 204 Aperture 400 Flash apparatus 401 Xenon tube 409 Near infrared light emitting diode

Claims (3)

An image sensor that photoelectrically converts a subject image formed by the imaging optical system and outputs a signal for generating a recording image; and
A filter that blocks components in the infrared wavelength region of light traveling from the imaging optical system toward the imaging device;
In an imaging mode in which light of the imaging optical system is incident on a light receiving sensor different from the imaging element, a first phase difference is detected between the plurality of images formed by the light from the imaging optical system using the light receiving sensor . 1 focus detection means;
Second focus detection means for detecting phase differences of a plurality of images formed by light from the imaging optical system using the imaging element in an imaging mode in which light of the imaging optical system is incident on the imaging element When,
When the focus state is detected by the first focus detection unit, the first light emitting unit that emits light in the infrared wavelength region corresponding to the sensitivity characteristic of the light receiving element of the first focus detection unit is caused to emit light,
And a light emission control unit that emits the second light emitting unit that emits light in a visible wavelength region corresponding to the sensitivity characteristic of the imaging element when the focus state is detected by the second focus detection unit. An imaging device. It can be attached to and detached from the imaging device according to claim 1,
A light emitting device comprising the first light emitting means and the second light emitting means. An image sensor that outputs a signal for generating a recording image by photoelectrically converting a subject image formed by the image pickup optical system, and a component in an infrared wavelength region of light traveling from the image pickup optical system to the image pickup element. In an imaging mode in which light from the imaging optical system is incident on a light- receiving sensor that is different from the filter and the image sensor , a plurality of images formed by light from the imaging optical system using the light-receiving sensor A plurality of images formed by light from the imaging optical system using the imaging element in an imaging mode in which light of the imaging optical system is incident on the imaging element; A second focus detection means for detecting the phase difference of the imaging device,
When the focus state is detected by the first focus detection unit, the first light emitting unit that emits light in the infrared wavelength region corresponding to the sensitivity characteristic of the light receiving element of the first focus detection unit is made to emit light. Light emission control step,
A second light emission control step of causing the second light emitting means to emit light in the visible light wavelength region corresponding to the sensitivity characteristic of the image sensor when the focus state is detected by the second focus detection means. And a method of controlling the imaging apparatus.