KR20100002051A - Photographing apparatus and method - Google Patents

Abstract

PURPOSE: A photographing apparatus and a photograph method measuring a distance as photoelectric conversion elements are provided to produce the distance to a subject of high accuracy by using photoelectric conversion elements arranged 2D. CONSTITUTION: An image beam is transformed into the electrical signal so that a plurality of photoelectric conversion elements is arranged 2D. A reading unit(152) sequentially reads out the electrical signal of photoelectric conversion elements from an element line. A distance calculating unit calculates the distance to the subject based on the difference of the distance calculator is the field-pattern of the electric signal of the first and the second device line.

Description

Imaging Apparatus and Imaging Method {Photographing apparatus and method}

The present invention relates to an image pickup device and an image pickup method. More particularly, the distance is measured by using photoelectric conversion elements arranged in a two-dimensional direction. The present invention relates to an image pickup apparatus and an image pickup method capable of calculating a distance to a subject with high precision without causing an error in the frame.

The digital still camera (imaging device) includes, for example, a single-lens reflex camera having a quick return mirror and guiding video light incident from the imaging optical system only before shooting, to the viewfinder side, and an imaging optical system even before shooting without the quick return mirror. And a compact camera for guiding the video light incident from the image pickup device (photoelectric conversion element).

The digital still camera controls the focus so that the video light of the subject is reflected on the imaging surface of the imaging device. The focus control of the digital still camera includes, for example, a phase difference detection method and a contrast detection method. The phase difference detection method detects the focusing position from the phase difference of two images of the subject, and drives the focus lens to the detected focusing position.

The contrast detection method acquires an image signal while moving the focus lens, detects the position with the highest contrast value (the position where the edge is detected most in the image), and determines the position of the focus lens at that time as the focusing position.

For example, Japanese Patent Laid-Open No. 2004-12815 (hereinafter referred to as Reference Document 1) discloses a technique using a CMOS (complementary metal oxide semiconductor) sensor in a phase difference detection method. Also, Japanese Patent Laid-Open No. 2006-324760 discloses a technique of adding a plurality of pixel values and converging with high precision when a subject is low in the contrast detection method.

The phase difference detection method separates the luminous flux from the subject into two and calculates the distance between the camera and the subject based on the distance at which the distribution of light appears (the light distribution appearance distance). In the conventional phase difference detection method, a line sensor has been used for the detection of light. The line sensor is a sensor composed of a plurality of photoelectric conversion elements arranged in a one-dimensional direction.

12 is an explanatory diagram showing the relationship between the view finder 10 and the distance measurement area 12 of the conventional imaging device. When the distance measuring area 12 is in the view finder 10, the line sensor 14 is disposed in the imaging device corresponding to the distance measuring area 12.

On the other hand, Reference Document 1 describes a case of using a CMOS sensor in which a plurality of photoelectric conversion elements are arranged in a two-dimensional direction instead of a line sensor. However, the technique of cited reference 1 is a technique of extracting and scanning one linear element like a line sensor from several elements constituting a CMOS sensor. Therefore, Cited Reference 1 is a technique having almost the same configuration as the conventional line sensor with respect to the scanning of the image light of the subject and the calculation of the distance.

In the phase difference detection method, the light beams from the subject are separated into two, for example, in the left and right directions, and irradiated to the line sensor 14.

13 is a graph showing an output value distribution of the line sensor 14 of the conventional imaging device.

As shown in FIG. 12, when the subject 5 exists in the distance measuring area 12, the distribution of the output value as shown in FIG. 13 can be obtained in each of the left and right parts of the line sensor 14. As shown in FIG. The inter-waveform distance A of the left and right output peak values changes according to the distance (imaging distance) between the imaging device and the subject. For example, as the imaging distance becomes longer, the inter-waveform distance A becomes shorter, and when the imaging distance becomes shorter, the inter-waveform distance A becomes longer. In order to calculate the distance A between waveforms, it is necessary to detect where the correlation between the two left and right waveforms is the strongest.

In the correlation detection method, for example, the sum of the differences with the other waveform data is taken while shifting one waveform data in units of pixels, and the distance when the total is minimum is determined as the distance between the waveforms having the strongest correlation (A). There is a way.

The correlation value at this time can be expressed by, for example, the following equation (1). In the output value distribution shown in Fig. 13, a graph showing the relationship between the correlation value and the distance between the waveforms as shown in Fig. 14 can be obtained. have. 14 is a graph showing the relationship between the correlation value and the distance between waveforms. When the correlation value becomes minimum (min1) and the distance A between waveforms in FIG. 13 corresponds.

Where n is the number of pixels in the region and j is the relative pixel position.

15 is an explanatory diagram showing the relationship between the view finder 10 and the distance measurement area 12 of the conventional imaging device. 16 is a graph showing an output value distribution of the line sensor 14 of the conventional imaging device.

17 is a graph showing the relationship between the correlation value and the distance between waveforms.

As shown in FIG. 15, when there are subjects 5 and 7 located on different photographing distances in the distance measuring area 12, the respective left and right portions of the line sensor 14 are the same as those shown in FIG. 16. The distribution of the output values can be obtained. When several output peak values are detected as shown in Fig. 16, there is a problem in that an error occurs when the distance is calculated by the two output value distributions, or the distance cannot be calculated.

In other words, if the correlation is detected when the waveform shown in FIG. 16 is shown, a graph showing the relationship between the correlation value and the distance between the waveforms can be obtained as shown in FIG. As shown in Fig. 17, the distance between the imaging device and the subject cannot be determined when the correlation values between the two waveforms A and B become equal to the minimum correlation value min2. In addition, when a plurality of output peak values are detected, there is a problem that the accuracy of distance detection is also lowered because the correlation value increases.

In this way, when distance determination is impossible, in the prior art, a method of first obtaining values between correlation values or replacing a predetermined distance with a predetermined distance in order to finally determine the distance between the imaging device and the subject. Was used, all had a problem of low reliability.

It is an object of the present invention to provide an imaging device and an imaging method which can calculate the distance to a subject with high accuracy.

Another object of the present invention is to be able to calculate the distance accurately even when a plurality of objects having different distances are mixed in one distance measuring area.

The present invention provides an imaging apparatus and an imaging method capable of measuring a distance to a subject with high accuracy using photoelectric conversion elements arranged in a two-dimensional direction.

An image pickup device according to the present invention comprises a plurality of photoelectric conversion elements arranged in a two-dimensional direction and converting image light incident from a subject into an electrical signal, and an element line comprising a plurality of photoelectric conversion elements arranged along one direction. In FIG. 1, a readout for sequentially reading an electrical signal of a photoelectric conversion element, and along an extension direction of an electrical signal of a first element line set and a plurality of element lines of a first element line set. And a distance calculator configured to calculate a distance to the subject based on a difference in the intensity distribution of the electrical signals of the second set of device lines, the plurality of device lines extending and parallel to each other. The device line may include a plurality of the photoelectric conversion devices disposed on one virtual line segment. The photoelectric conversion elements arranged in the two-dimensional direction may constitute an imaging device, and the first device line set and the second device line set may be included in a distance measuring area that is a part of the imaging device.

With the above-described configuration, the imaging element may have a plurality of photoelectric conversion elements arranged in a two-dimensional direction for converting the image light of the subject incident on the light-receiving surface from the subject into an electrical signal, wherein the reader is one of some of the imaging elements. An electrical signal is sequentially read out for each photoelectric conversion element in a device line including a plurality of photoelectric conversion elements disposed on the virtual line segment. The distance calculator includes a first device line set including a plurality of device lines parallel to each other included in a distance measurement area that is a part of an image pickup device, and a distance measurement unit disposed on an extension line in a length direction of the first device line set. The distance to the subject can be calculated based on the difference in the distribution of the intensity of the electrical signals of the second set of element lines composed of several element lines parallel to each other included in the area.

In the present invention, the distance calculator is on the same straight line as the intensity distribution of the first element line, which is one of the element lines constituting the first element line set, and the first element line among the element lines constituting the second element line set. The distance may be calculated by comparing the intensity distributions of the arranged second device lines. With this configuration, the first element line and the second element line are arranged on the same straight line, and the intensity distribution of the first element line and the intensity distribution of the second element line are compared to calculate the distance to the subject. .

In the present invention, the distance calculator is based on a first value based on an addition value of the electric signals of the photoelectric conversion elements arranged along a direction different from the length direction of the device line, that is, the direction transverse to the direction in which the device line extends. The distance may be calculated by comparing the intensity distribution of the element line set and the intensity distribution of the second element line set. With such a configuration, the intensity of each electric signal output from a plurality of photoelectric conversion elements arranged in a direction different from the longitudinal direction of the element line can be added to obtain an added value of the intensity of the electric signal, based on this addition value. The distance to the subject may be calculated by comparing the intensity distribution of the first element line set and the intensity distribution of the second element line set.

In the present invention, the number of photoelectric conversion elements arranged along the direction transverse to the direction in which the distance calculating unit adds the intensity of the electrical signal to the device line in a direction different from the length direction of the device line, i. It may vary depending on the luminance level of the video light. With such a configuration, the number of photoelectric conversion elements arranged in a direction different from the length direction of the element line added by the distance calculating unit can be varied according to the luminance level of the image light of the subject. Therefore, the sensitivity can be improved according to the luminance level of the image light of the subject.

In the present invention, the photoelectric conversion elements arranged in a direction different from the longitudinal direction of the element line for adding the intensity of the electrical signal, i.e., arranged along the direction of extension of the element line, to obtain the addition value, The photoelectric conversion elements of the first device line set and the second device line set may be selected to not overlap each other. With such a configuration, when the strengths of the electrical signals of the photoelectric conversion elements arranged in the direction different from the longitudinal direction of the element lines are added, the photoelectric conversion elements are extracted so as not to overlap each other. Thus, a high precision added signal strength can be obtained.

In the present invention, the photoelectric conversion elements arranged along the direction crossing the extension direction of the element line for adding the electric signal to the distance calculator to obtain the addition value may be arranged on a straight line. By such a configuration, when the intensity of the electrical signal of the photoelectric conversion element arranged in a direction different from the longitudinal direction of the element line is added, the photoelectric conversion element arranged on one virtual straight line in a direction different from the longitudinal direction of the element line Can be extracted.

In the present invention, the plurality of photoelectric conversion elements may be arranged in a matrix or honeycomb shape. With such a configuration, an imaging device composed of a plurality of photoelectric conversion elements arranged in a matrix or honeycomb shape can be applied.

In the present invention, the first element line set and the second element line set may be selected by a user among the optical conversion elements. With this configuration, the first element line set and the second element line set are selected from all the optical conversion elements by selection by the user.

The imaging method according to the present invention includes the steps of sequentially reading an electrical signal for each photoelectric conversion element from a device line in which a plurality of photoelectric conversion elements for converting image light incident from a subject into an electrical signal are arranged along one direction; The electrical signal of the first element line set composed of a plurality of element lines parallel to each other, and the second element line set composed of a plurality of element lines parallel to each other and extending along an extension direction of the element lines of the first element line set. Calculating a distance to the subject based on the difference in the intensity distribution of the electrical signal. The device line may include a plurality of the photoelectric conversion devices disposed on one virtual line segment. The photoelectric conversion elements arranged in the two-dimensional direction may constitute an imaging device, and the first device line set and the second device line set may be included in a distance measuring area that is a part of the imaging device.

With the above-described configuration, the imaging element has a plurality of photoelectric conversion elements arranged in a two-dimensional direction for converting the image light of the subject incident on the light-receiving surface from the subject into an electrical signal, and is disposed on one virtual line segment of some of the imaging elements. A first device line set comprising a plurality of device lines parallel to each other included in a distance measuring area which is an area of a part of the imaging device, in which an electrical signal is sequentially read out for each photoelectric conversion device in a device line composed of a plurality of photoelectric conversion devices And on the basis of the intensity distribution difference of the electrical signal with the second element line set composed of several element lines parallel to each other included in the same distance measuring region, which are disposed on the extension line in the longitudinal direction of the first element line set. The distance to the subject is calculated.

As described above, the image pickup device and the image pickup method of the present invention measure the distance using photoelectric conversion elements arranged in the two-dimensional direction, and thus an error in calculating the distance even when several objects having different distances are mixed in one distance measurement area. The distance to the subject can be calculated with high accuracy.

EMBODIMENT OF THE INVENTION Hereinafter, the structure and operation | movement of the imaging device and imaging method which concern on this invention are demonstrated in detail through embodiments of an accompanying drawing. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals to omit duplicate explanation.

(First embodiment)

1 is a block diagram showing an image capturing apparatus 100 according to an embodiment of the present invention. Although the imaging device 100 is a digital single-lens reflex camera, for example, the imaging device of this invention is not limited to this, It may be a compact digital camera.

The imaging apparatus 100 according to the embodiment shown in FIG. 1 includes, for example, an imaging optical system 101, a quick return mirror 105, a shutter 106, a CMOS sensor 107, and an image input controller ( 110, AF sensor 111, DSP / CPU 120, CPU 130, operation member 135, drivers 141, 143, 145, motors 142, 144, 146 Image signal processing circuit 152, compression processing circuit 154, LCD driver 156, LCD 158, VRAM 162, SDRAM 164, media controller 166, And a recording medium 168.

The imaging optical system 101 includes, for example, a zoom lens 102, an aperture 103, a focus lens 104, and the like. The imaging optical system 101 is an optical system that forms external optical information onto the CMOS sensor 107, and transmits image light (image of a subject) incident from a subject to the CMOS sensor 107. The zoom lens 102 is a lens for changing the angle of view by changing the focal length. The zoom angle may be adjusted by the user, or may be controlled by a motor and a driver not shown. The diaphragm 103 is a mechanism for adjusting the amount of light passing through and is driven by the motor 142. The focus lens 104 focuses the image light of the subject on the imaging surface of the CMOS sensor 107 by moving in the optical axis direction. The focus lens 104 is driven by the motor 144. The motors 142 and 144 receive driving signals from the drivers 141 and 143, respectively.

The quick return mirror 105 includes a half mirror member that reflects incident light and transmits part of the incident light, and a submirror provided on the rear surface (CMOS sensor 107) side of the half mirror member. Before the photographing, the quick return mirror 105 is in a so-called mirror down (moved downward) position and is disposed on an optical path connecting the imaging optical system 101 and the CMOS sensor 107 to block the optical path. In addition, the half mirror member of the quick return mirror 105 reflects the image light incident from the imaging optical system 101 before the main photographing to the view finder side. In addition, the sub-mirror of the quick return mirror 105 reflects the light transmitted through the half mirror member to the AF sensor 111 side before the main photographing.

The quick return mirror 105 moves to a so-called mirror up (moved upward) position at the time of the main shooting, and opens an optical path connecting the imaging optical system 101 and the CMOS sensor 107 to capture the image light incident from the subject. The CMOS sensor 107 is reached.

The shutter 106 is a mechanical shutter, which opens an optical path connecting the imaging optical system 101 and the CMOS sensor 107 so that the image light is incident on the CMOS sensor 107 at the time of photographing, and blocks the image light when not photographing. do. The shutter 106 controls the exposure time of the CMOS sensor 107. The quick return mirror 105 and the shutter 106 are driven by the motor 146 and interlock with each other. The motor 146 is driven by receiving a drive signal from the driver 145.

The CMOS sensor 107 is an example of an image pickup device, and includes a plurality of photoelectric conversion devices that photoelectrically convert image light (light information) incident through the imaging optical system 101 into an electrical signal. Equipped. Each photoelectric conversion element generates an electrical signal in accordance with the amount of light. The imaging device is not limited to a CMOS sensor, and a charge coupled device (CCD) sensor may be used. At this time, an electronic shutter (not shown) may be applied to the shutter 106 instead of the mechanical shutter. In addition, the operation of the shutter 106 or the electronic shutter can be performed by a switch operation of the shutter button (operation member 135) connected to the DSP / CPU 120.

The CMOS sensor 107 also includes a CDS / AMP unit 108 and an A / D conversion unit 109. The CDS / AMP unit (correlated double sampling circuit, amplifier) 108 amplifies the electrical signal to an arbitrary level while removing low frequency noise included in the electrical signal output from the CMOS sensor 107. Let's do it. The A / D converter 109 digitally converts the electrical signal output from the CDS / AMP unit 108 to generate a digital signal. The A / D converter 109 outputs the generated digital signal to the image input controller 110.

The image input controller 110 processes the digital signal output from the A / D converter 109 to generate an image signal capable of image processing. The image input controller 110 outputs the generated image signal to the image signal processing circuit 152, for example. The image input controller 110 also controls reading and writing of image data to the SDRAM 164.

The AF sensor 111 is a CMOS sensor including a plurality of photoelectric conversion elements arranged in a two-dimensional direction. The AF sensor 111 receives the light from the sub-mirror of the quick return mirror 105 and generates an electric signal according to the amount of light before the photographing. The AF sensor 111 outputs the generated electric signal to the CPU 130. The AF sensor 111 may include a CDS / AMP unit 112 and an A / D conversion sensor 113.

The reading unit sequentially reads an electrical signal for each photoelectric conversion element from an element line including a plurality of photoelectric conversion elements (arranged in one direction) disposed on a virtual line segment of one of the photoelectric conversion elements of the AF sensor 111. An example of the reading unit may be a CDS / AMP unit 112 and an A / D conversion sensor 113 of the AF sensor 111. However, the reading unit of the present invention is not limited thereto, and the reading unit is an AF sensor. It may also be an image input controller 131 which processes the output signal of 111.

The AE sensor 114 is a photoelectric conversion element, for example. The AE sensor 114 receives the light from the subject and generates an electric signal according to the amount of light before the photographing. The AE sensor 114 outputs the generated electric signal to the CPU 130.

The DSP / CPU 120 and the CPU 130 function as a calculation processing device and a control device by a program, and control the processing of each component installed in the imaging device 100. The CPU 130 mainly operates before and during main shooting, and the DSP / CPU 120 mainly operates after shooting.

The CPU 130 outputs a signal to the drivers 141, 143, and 145 based on focus control and exposure control, for example, to drive the imaging optical system 101, the quick return mirror 105, and the shutter 106. . The CPU 130 also controls each component of the imaging device 100 based on the signal from the operation member 135. The DSP / CPU 120 controls image processing and the like with respect to the image signal acquired by shooting.

In addition, in the present embodiment, the DSP / CPU 120 and the CPU 130 are shown as being provided one by one, but may be composed of a plurality of CPUs, such as causing each CPU to execute a signal system command and an operation system command. .

As shown in FIG. 1, the DSP / CPU 120 includes, for example, a timing generator 121, an appropriate AWB calculation unit 122, an image processing selection unit 123, an SIO 124, and the like. do. The CPU 130 includes, for example, an image input controller 131, an AF operation control unit 132, an AE operation control unit 133, a GUI management unit 134, an SIO 136, and the like.

The timing generator 121 outputs a timing signal to the CMOS sensor 107 or the CDS / AMP unit 108 to control charge reading of each photoelectric conversion element included in the CMOS sensor 107.

The appropriate AWB calculator 122 calculates the WB control value based on the color information of the image signal corresponding to the video light of the subject received by the CMOS sensor 107. The appropriate AWB calculator 122 calculates, for example, a WB control value for obtaining an appropriate white balance (WB) according to the subject. The appropriate AWB calculating unit 122 sends the calculated WB control value to the image signal processing circuit 152.

The image processing selector 123 selects whether or not to process an image such as gamma correction, outline enhancement processing, or the like on the image signal, or sets parameters required for each image processing. The image processing selection unit 123 sends the selection result or the set parameter to the image signal processing circuit 152.

The image input controller 131 processes the digital signal output from the A / D conversion sensor 113 to generate a signal capable of focus control. The image input controller 131 outputs the generated signal to the AF operation control unit 132, for example.

The AF operation control unit 132 generates a control signal for moving the focus lens 104 in one direction when receiving the focus control start operation signal, and outputs the generated control signal to the driver 143.

The AF operation control unit 132 calculates an AF (auto focus) evaluation value and further calculates a focusing position of the focus lens 104 based on the AF evaluation value. The AF evaluation value is calculated based on the luminance value of the signal output from the AF sensor 111.

The AF operation control unit 132 is an example of a distance calculation unit and is arranged on an electrical signal of a first element line set including a plurality of element lines parallel to each other, and disposed on an extension line in the longitudinal direction of the first element line set and parallel to each other. The distance between the subject and the imaging device 100 is calculated based on the difference in the intensity distribution of the electrical signal with the second set of element lines consisting of several element lines. That is, the AF operation control unit 132 is an example of the distance calculation unit included in the imaging device of the present invention.

The AF operation control unit 132 generates the in-focus position obtained as a result of the calculation as a control signal and outputs it to the driver 143. The driver 143 generates a drive signal based on the control signal input from the AF operation controller 132. The driver 143 sends the generated drive signal to the motor 144.

The AE calculation control unit 133 calculates the AE (auto exposure) evaluation value and calculates the aperture amount of the aperture 103 and the shutter speed of the shutter 106 based on the calculated AE evaluation value. Also, the AE evaluation value is calculated based on the luminance value of the AE sensor 114. The AE calculation control unit 133 generates the calculated aperture value or shutter speed as a control signal and outputs them to the drivers 141 and 145, respectively. The drivers 141 and 145 generate a driving signal based on the control signal input from the AE calculation controller 133. The drivers 141 and 145 send the generated driving signals to the motors 142 and 146.

In addition, in this embodiment, the AE calculation control unit 133 controls the AF sensor 111 based on the AE evaluation value. For example, when the subject is low luminance, the luminance is usually so that the output value of the photoelectric conversion elements arranged in a direction different from the length direction of the element line (the direction transverse to the direction in which the element line extends, that is, the vertical direction) can be added. Compared to this, electrical signals are output from a large number of device lines.

The GUI management unit 134 manages a graphical user interface (GUI) such as a thumbnail screen of an image displayed on the LCD 158 and a menu screen for operating the imaging device 100. The GUI management unit 134 receives an operation signal from the operation member 135, for example, and sends a control signal based on the operation signal to the LCD driver 156.

The SIOs 124 and 136 are input / output interfaces for inputting and outputting signals to and from each other.

The operation member 135 is, for example, an up, down, left, right key, power switch, mode dial, shutter button, or the like provided in the imaging device 100. The operation member 135 sends an operation signal to the CPU 130 or the like based on the operation by the user. For example, the shutter button can be pressed halfway, fully pressed, or released by the user. The shutter button outputs the focus control start operation signal when it is pressed halfway, and the focus control is terminated by releasing the half press. The focus button outputs the shooting start operation signal when the focus button is pressed completely.

The image signal processing circuit 152 receives the image signal from the image input controller 110 and generates an image processed image signal based on the WB control value, gamma value, outline enhancement control value, and the like. The compression processing circuit 154 receives an image signal before compression processing and compresses the image signal in a compression format such as, for example, a JPEG compression format or an LZW compression format. The compression processing circuit 154 sends the image data generated by the compression processing to the media controller 166, for example.

The LCD driver 156 receives image data from the VRAM 162, for example, and displays an image on a liquid crystal display (LCD) 158. The LCD 158 is provided in the main body of the imaging device 100. The image displayed by the LCD 158 may be, for example, an image before shooting (live view display) read out from the VRAM 162, various setting screens of the imaging device 100, an image captured and recorded, or the like. In addition, in the present embodiment, although the display unit is the LCD 158 and the display driver is the LCD driver 156, the present invention is not limited to the above example, and may be, for example, an organic EL display, its display driver, or the like.

The VRAM (video RAM) 162 is an image display memory and has several channels. The VRAM 162 can simultaneously perform input of image data for image display from the SDRAM 164 and output of image data to the LCD driver 156. The resolution or maximum number of colors of the LCD 158 depends on the capacity of the VRAM 162.

An SDRAM (synchronous DRAM) 164 is an example of a storage unit, and temporarily stores image data of a captured image. The SDRAM 164 has a storage capacity capable of storing image data of several images. The SDRAM 164 also preserves the operation program of the DSP / CPU 120. Reading and writing of the image to the SDRAM 164 are controlled by the image input controller 110.

The media controller 166 controls the writing of the image data to the recording medium 168 or the reading of the image data and setting information recorded on the recording medium 168. The recording medium 168 may be, for example, an optical disk (CD, DVD, Blu-ray disk, etc.), a magneto-optical disk, a magnetic disk, a semiconductor storage medium, or the like, and records photographed image data. The media controller 166 and the recording medium 168 may be detachably installed in the imaging device 100.

In addition, a series of processes in the imaging apparatus 100 may be processed by hardware, and may be implemented by the software process by the program on a computer.

2 is a schematic diagram showing the relationship and configuration of the focus lens 104, the CMOS sensor 107, the condenser lens 172, the separator lens 174, and the AF sensor 111. Hereinafter, an optical system such as the focus lens 104 and the AF sensor 111 will be described in detail.

The CMOS sensor 107 in FIG. 2 points to the imaging surface. The relationship between the subject A point on the optical axis and the focus lens 104 is in a confocal state, and the relationship between the subject B point on the optical axis and the focus lens 104 is in a state where the subject is focused in front, and the subject C point and the focus on the optical axis are focused. The relationship between the lenses 104 is that the subject is focused on the back side.

A part of the image light passing through the focus lens 104 (the gray portion in FIG. 2) at the object A point on the optical axis is focused onto the imaging surface, and then bent toward the separator lens 174 side to the condenser lens 172 of the AF sensor 111. Lose. The curved light is split by the separator lens 174, and the split light flux is imaged again on the light receiving surface 176 of the AF sensor.

3 is a schematic diagram showing the split light beam 182 at the focus lens position.

The optical axis of the separator lens 174 is eccentric with respect to the condenser lens 172. Therefore, the position where the image of the subject is imaged on the light-receiving surface of the AF sensor 111 according to the focus state (the focus in front of the focus or the front and the focus in the rear) is the eccentricity of the optical axis of the separator lens 174. Staggered in the direction. This staggered amount corresponds to the focus state, and the focus state can be detected by calculating the interval of the video light of the pair of subjects when the divided pair of luminous fluxes are imaged on the light receiving surface of the AF sensor 111.

Of the plurality of photoelectric conversion elements disposed in the AF sensor 111, photoelectric conversion elements arranged in parallel with the eccentric direction are selected as one element line. As a result, the interval of the image light of the subject formed in the AF sensor 111 can be calculated.

4 is an explanatory diagram showing a relationship between the view finder 10 and the distance measuring area 12 of the imaging device 100 of the present embodiment. Hereinafter, the phase difference detection method of the present embodiment will be described.

The phase difference detection method separates the light beams from the subject into two and calculates the distance between the imaging device 100 and the subject based on the distribution appearance distance of the light. In the phase difference detection method of this embodiment, the AF sensor 111 to which the CMOS sensor is applied to the detection of light is used. And a plurality of horizontal element lines 184 and 186 including a plurality of photoelectric conversion elements (along one direction) disposed on a virtual line segment among the photoelectric conversion elements arranged in the two-dimensional direction of the AF sensor 111. , 188). Horizontal device lines 184, 186, 188 are parallel to each other. A plurality of photoelectric conversion elements are disposed in the one-dimensional direction on the horizontal element lines 184, 186, and 188, respectively. When the distance measuring area 12 is set in the view finder 10, three horizontal lines 184, 186, and 188 are disposed in the imaging device corresponding to the distance measuring area 12.

In addition, in the present embodiment, unlike the technique of Citation 1, which extracts one horizontal line from the CMOS sensor, several parallel horizontal lines are used as the sensor in the CMOS sensor of the AF sensor 111. Multiple parallel horizontal lines are included in the same distance measuring area. The distance measuring area is a part of the CMOS sensor 107, and the distance measuring area applied to the CMOS sensor 107 of the present embodiment is the minimum unit (minimum area) when performing the distance measuring operation. And this distance measuring area has a relationship with the distance measuring area (edge for confirming a confocal) of the minimum unit displayed on the LCD 158, for example. In addition, one distance measurement area of the present embodiment does not refer to one multi-AF system composed of several distance measurement minimum units, but refers to one minimum unit when performing a distance measurement operation.

In the phase difference detection method of this embodiment, the light beams from the subject are separated into two, for example, in the left and right directions, and irradiated to the horizontal lines 184, 186, and 188. When there are two subjects 5 and 7 in the distance measuring area 12 shown in FIG. 4, the left and right portions of the horizontal lines 186 and 188 located above or below the distribution of the output values shown in the upper part of FIG. 5. Can be obtained respectively. This is because only the subject 5 is imaged on the horizontal lines 186 and 188. On the other hand, in the left and right portions of the center horizontal line 184, the same distribution as the output value shown in the lower part of FIG. This is because the subjects 5 and 7 are imaged on the horizontal lines 186 and 188.

5 is a graph showing the distribution of output values of the horizontal lines 184, 186, 188 of the imaging apparatus 100 of the present embodiment. The distance between the waveforms of the peak values of the left and right outputs changes depending on the distance between the imaging device and the subject. For example, the longer the shooting distance, the shorter the distance between waveforms, and the shorter the shooting distance, the longer the distance between waveforms.

In FIG. 5, the inter-waveform distance A of the left and right output peak values corresponds to the distance between the imaging device 100 and the subject 5, and the inter-waveform distance B is between the imaging device 100 and the subject 7. Corresponds to the distance. In order to calculate the distances A and B between the waveforms, it is necessary to detect where the correlation between the two left and right waveforms is the strongest.

In the correlation detection method, for example, a waveform having the strongest correlation is obtained by shifting the waveform data of one side by pixel by taking the total sum of the differences with the other waveform data and minimizing the total distance. There is a way to judge the distance between.

The correlation value at this time can be expressed by, for example, Equation (2). In the output value distribution shown in the upper part of FIG. 5, the relationship between the correlation value and the waveform distance as shown in FIG. 14 can be obtained. In the output value distribution shown in the lower part of FIG. 5, the correlation value and the distance between the waveform as shown in FIG. You can get a relationship. In FIG. 14, the correlation minimum value min1 corresponds to the distance A between waveforms at the top of FIG. 5. In addition, in FIG. 17, the correlation minimum value min2 corresponds to the distance between the waveforms A and B at the bottom of FIG. 5.

Where n is the number of pixels in the region and j is the relative pixel position.

In this embodiment, not only the distribution of the output values detected in the center horizontal line 184 but also the distribution of the output values detected in the horizontal lines 186 and 188 located above or below. Since a plurality of data are used, the distance between the imaging device 100 and the subject can be calculated more accurately. In addition, even when the peak value of a plurality of output values are detected, unlike the case of using one horizontal line or a conventional line sensor, there is no problem that an error or distance calculation is impossible. As a result, the distance between the imaging device 100 and the subject can be calculated more accurately.

Next, the element line on the AF sensor 111 will be described. 6 and 7 are plan views showing the arrangement of the photoelectric conversion elements of the AF sensor 111 according to the present embodiment.

Each photoelectric conversion element of the CMOS sensor applied to the AF sensor 111 may be composed of a matrix pattern as shown in FIG. 6, or may be composed of a honeycomb pattern as shown in FIG. 7. The matrix pattern is a pattern in which a plurality of photoelectric conversion elements are arranged in the vertical direction in the horizontal direction and in the horizontal direction. The honeycomb pattern is a pattern in which a plurality of photoelectric conversion elements are arranged in a direction having an angle other than 90 degrees with respect to the horizontal direction and the horizontal direction.

In the AF sensor 111 shown in FIG. 6, an element line made up of a plurality of photoelectric conversion elements arranged on one virtual line, that is, photoelectric conversion elements arranged in one direction when phase difference detection is performed in focus control. Electrical signals output at (L11, L12, L13, R11, R12, R13) are sequentially read out for each photoelectric conversion element. The photoelectric conversion elements shaded in FIG. 6 represent each device line. The line connecting L11 and R11 corresponds to the horizontal line 186 shown in FIG. 6, the line connecting L12 and R12 corresponds to the horizontal line 184, and the line connecting L13 and R13 is the horizontal line 188. Corresponds to.

In addition, the combination of the element lines L11, L12, and L13 arranged on one side is called a first element line set, and the combination of the element lines R11, R12, and R13 arranged on the other side is called a second element line set. . The device line sets are included in a distance measurement area, which is an area of some of the CMOS sensors 107.

In addition, the AF operation control unit 132 calculates a correlation between the intensity distribution of the output value of the element line L11 and the intensity distribution of the output value of the element line R11 and calculates a distance from the subject. In addition, in this embodiment, since the correlation is calculated for several lines, the correlation between the element lines L12 and R12 and the correlation between the element lines L13 and R13 are calculated.

In the AF sensor 111 shown in FIG. 7, as in the case of FIG. 6, the element lines L21, L22, L23, which are formed of a plurality of photoelectric conversion elements disposed on one virtual line segment, that is, disposed in one direction. The electrical signals output from R21, R22, and R23 are sequentially read out for each photoelectric conversion element. The AF operation control unit 132 calculates the correlation between the element lines L21 and R21, the correlation between the element lines L22 and R22, and the correlation between the element lines L23 and R23.

(Operation of the First Embodiment)

Next, with reference to FIG. 8, the operation | movement distance calculation operation in the focus control of the imaging device which concerns on a present Example is demonstrated. 8 is a flowchart showing an operation for calculating a shooting distance in focus control of the imaging device according to the present embodiment.

First, an output value (pixel value) output from each photoelectric conversion element is acquired (read out) for each horizontal line (for example, horizontal lines 184, 186, 188, etc.) of the AF sensor 111 (step S101). . The correlation is calculated by comparing the intensity distributions of the output values of the left and right element lines of the AF sensor 111 (step S102). For example, the correlation between the element lines L11 and R11, the correlation between the element lines L12 and R12, and the correlation between the element lines L13 and R13 are calculated.

Next, the minimum value among the calculated correlation values is maintained for each horizontal line (step S103). Then, it is judged whether or not the minimum value of the maintained correlation value is lower than the predetermined value (step S104). In other words, the lower the correlation value, the higher the correlation between the element lines, so that the reliability is high. Therefore, if the minimum value of the correlation value is lower than the predetermined value, the process proceeds to step S106 without any special processing. On the other hand, if the minimum value of the correlation value is higher than the predetermined value, it is determined that the reliability is low with respect to the horizontal line and is excluded from the distance calculation target (step S105). This enables more reliable distance calculation.

Next, the kurtosis (sharpness) of the graph is evaluated as to what shape the graph showing the relation between the correlation value and the distance between the waveforms (for example, the graph shown in Figs. 14 and 17) (step S106). . If the shape of the graph showing the relationship between the correlation value and the distance between the waveforms is a one-mount distribution with one mountain, it can be determined that there is one object. On the other hand, if the shape of the graph is not in the form of a single distribution, it may be determined that the subject has a plurality of different distances (step S107). If the shape of the graph is not in the one-distribution form, the horizontal line is excluded from the distance calculation target (step S108). On the other hand, if the shape of the graph is a one-distribution distribution, the flow proceeds to step S109. This can limit the subject for which the distance is to be calculated.

Next, as a result of the above processing, the output value of the remaining horizontal line is regarded as a high reliability value, and the distance between the waveforms is calculated based on the output value of the horizontal line, and the imaging distance between the imaging device 100 and the subject is further calculated. . If there are several horizontal lines remaining, the photographing distance is determined first by the line having the shortest photographing distance (the line having the longest waveform distance) (step S109). By the above steps, the shooting distance in the focus control of the imaging apparatus 100 can be determined.

In addition, in the said embodiment, although the case where three horizontal lines were provided in the part corresponding to one distance measuring area | region was demonstrated, this invention is not limited to the said example. The imaging apparatus 100 may be provided with a plurality of distance measuring regions, and may be provided with a plurality of horizontal lines in portions corresponding to the respective distance measuring regions. The photographing distance is calculated by performing the processing of steps S101 to S109 for each distance measuring area. Thereafter, the optimum shooting distance is determined by comparing the distances obtained for each distance measuring area.

According to the present embodiment, when several subjects having different distances are mixed in one distance measuring area, no error occurs when calculating the distance, and thus the accuracy of the calculation result can be further improved. In addition, since the CMOS sensor in which the photoelectric conversion element is disposed in the two-dimensional direction is used as the AF sensor 111, there is a degree of freedom in the detection range of the image light of the subject as compared with the case where a plurality of line sensors are arranged in parallel. In other words, when the line sensors are arranged in parallel, there is a gap between the line sensors because each line sensor has a thick package. As a result, a limitation occurs in the detection range of the image of the subject. On the other hand, in the CMOS sensor as in the present embodiment, since the read position can be specified in units of photoelectric conversion elements, the degree of detection range is high.

In addition, in the CMOS sensor as shown in the present embodiment, since a plurality of photoelectric conversion elements are disposed in close proximity in the two-dimensional direction, even if an installation error of the apparatus main body of the AF sensor 111 occurs, the readout position may be changed, so that adjustment is simple. . On the other hand, since the photoelectric conversion elements of the prior art using the line sensor are arranged only in the one-dimensional direction, the installation accuracy is high and the manufacturing process is difficult.

(2nd Example)

9 and 10 are plan views showing the arrangement of the photoelectric conversion elements of the AF sensor 111 according to the present embodiment. Hereinafter, the imaging apparatus 100 according to the second embodiment of the present invention will be described.

9 shows a case where each photoelectric conversion element of the CMOS sensor applied to the AF sensor 111 is arranged in a matrix pattern. 10 shows a case where each photoelectric conversion element is arranged in a honeycomb pattern.

The second embodiment has a different reading range of each photoelectric conversion element than in the first embodiment. The reading range will be described below. In the first embodiment, as shown in Fig. 11A, the correlation between two element lines L30 and R30 included in one horizontal line was calculated. At this time, the output value was acquired in the unit of one photoelectric conversion element enclosed by the thick line.

On the other hand, in the present embodiment, a plurality of element lines L31, L32, L33, and L34 parallel to each other on one side are defined as a first element line set as a pair, and several element lines R31 parallel to each other on the other side , R32, R33, and R34) are defined as the second element line set as one pair.

Then, the output values of the photoelectric conversion elements and the like in the direction different from the scanning direction (the longitudinal direction of the element line) (for example, the vertical direction crossing the extending direction of the element line) are added. For example, in the example shown to FIG. 11 (B), the addition value of the output value of four photoelectric conversion elements enclosed by the thick line is acquired. The four photoelectric conversion elements surrounded by the thick line are treated as one pixel, and the correlation is calculated by comparing the intensity distributions of the output values (addition values) of the pixels in the scanning direction based on this.

The example of the honeycomb pattern shown in FIG. 10 is also the same. In the first embodiment, as shown in Fig. 10A, output values are obtained in units of one photoelectric conversion element surrounded by thick lines in the element lines L40 and R40. On the other hand, according to this embodiment, as shown in Fig. 10B, the first element line set consisting of the element lines L41 and L44 and the second element line set consisting of the element lines R41 and R44 are thicker. The four photoelectric conversion elements surrounded by lines are treated as one pixel, and the correlation is calculated by comparing the intensity distributions of the output values (addition values) of the pixels in the scanning direction based on this. Further, as shown in Fig. 10B, for example, the photoelectric conversion elements to be added by extracting device lines at intervals of one line are selected from the photoelectric conversion elements arranged in a direction perpendicular to the scanning direction. As shown in 10 (C), the element lines may be extracted to be adjacent to each other. At this time, as shown in Fig. 10C, in the first element line set made of the element lines L45 and L48, and the second element line set made of the element lines R45 and R48, surrounded by thick lines. Four photoelectric conversion elements are treated as one pixel. The photoelectric conversion elements to be added are arranged in a zigzag along a direction substantially perpendicular to the scanning direction.

According to the present embodiment, even when a sufficient dynamic range cannot be obtained in the unit of one photoelectric conversion element in the AF sensor 111, since the output values of the plurality of photoelectric conversion elements are added, the dynamic range of each photoelectric conversion element is narrow. It can be supplemented to increase the sensitivity. In addition, when pixels in the direction perpendicular to the scanning direction are added, data with good plasticity can be obtained because no component in the scanning direction is included. In addition, according to this embodiment, a high-sensitivity AF sensor can be realized by a normal CMOS sensor. Therefore, development and manufacture of a separate high-sensitivity photoelectric conversion element are not necessary, and the increase in cost can be suppressed.

In addition, in the first embodiment, several element lines parallel to each other are read to improve the accuracy of distance calculation when several subjects are included in the distance measurement area.

In this embodiment, by reading a plurality of element line sets composed of several element lines parallel to each other, it is possible to improve the distance calculation accuracy when a plurality of subjects are included in the high sensitivity and distance measurement area. 11 is a plan view showing the arrangement of the photoelectric conversion elements of the AF sensor 111 according to the present embodiment.

FIG. 11A shows a case where an output value is obtained in units of one photoelectric conversion element surrounded by a thick line in the element lines L50, L60, L70, R50, R60, and R70. In this embodiment, as shown in Fig. 11B, four photoelectric conversion elements enclosed by a thick line are treated as one pixel, and the correlation is obtained by comparing the intensity distributions of the output values (addition values) of the pixels in the scanning direction. Calculate.

The element line set in Fig. 11B is an element line set composed of element lines L51, L52, L53, and L54, an element line set composed of element lines R51, R52, R53, and R54, and an element line L61. Device line set consisting of L62, L63, L64, Device line set consisting of device lines R61, R62, R63, R64, Device line set consisting of device lines L71, L72, L73, L74, Device line R71 There is a set of device lines consisting of R72, R73, and R74.

At this time, the photoelectric conversion elements perpendicular to the scanning direction are added among the photoelectric conversion elements that do not overlap with the element line sets. As a result, the AF sensor 111 may detect the image light of the subject with high accuracy.

The number (addition number) of the photoelectric conversion elements arranged in a direction different from the length direction of the element line to be added (for example, a vertical direction crossing the direction in which the element line extends) depends on the luminance level of the image light of the subject. It can be variable.

For example, the AE operation control unit 132 receives the output value of the AE sensor 114 to determine the luminance level. The AE operation control unit 132 determines the addition necessity or the addition number and sends the result to the AF sensor 111. This makes it possible to realize an AF sensor having sensitivity according to the brightness of the subject.

Although the present invention has been described with reference to the above-described embodiments, these are merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the appended claims.

1 is a block diagram showing an imaging device according to an embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating a relationship and a schematic configuration of a focus lens, a CMOS sensor, a condenser lens, a separator lens, and an AF sensor included in the imaging device of FIG. 1.

FIG. 3 is a schematic diagram showing the luminous flux divided at the position of the focus lens of FIG. 2.

4 is an explanatory diagram showing a relationship between the view finder 10 and the distance measuring area 12 of the imaging device of FIG. 1.

5 is a graph showing an output value distribution of a horizontal line of the imaging device of FIG. 1.

6 is a plan view illustrating an example of the arrangement of the photoelectric conversion elements of the AF sensor included in the imaging device of FIG. 1.

7 is a plan view illustrating another example of the arrangement of the photoelectric conversion elements of the AF sensor included in the imaging device of FIG. 1.

8 is a flowchart illustrating an operation of calculating a shooting distance in focus control of the imaging device of FIG. 1.

9 is a plan view showing the arrangement of the photoelectric conversion elements of the AF sensor included in the imaging device according to another embodiment of the present invention.

10 is a plan view illustrating another example of the arrangement of the photoelectric conversion elements of the AF sensor of FIG. 9.

11 is a plan view illustrating another example of the arrangement of the photoelectric conversion elements of the AF sensor of FIG. 9.

It is explanatory drawing which shows the relationship with the viewfinder and distance measuring area of the conventional imaging device.

13 is a graph showing a distribution of output values of a line sensor of a conventional imaging device.

14 is a graph showing the relationship between the correlation value and the distance between waveforms.

15 is an explanatory diagram showing a relationship between a view finder and a distance measurement area in a conventional imaging device.

16 is a graph showing a distribution of output values of a line sensor of a conventional imaging device.

17 is a graph showing the relationship between the correlation value and the distance between waveforms.

* Explanation of symbols for main parts of the drawings

100: imaging device 130: CPU

101: imaging optical system 135: operating member

102: Zoom lens 141, 143, 145: Driver

103: aperture 142, 144, 146: motor

104: focus lens 152: image signal processing circuit

105: quick return mirror 154: compression processing circuit

106: shutter 156: LCD driver

107: CMOS sensor 158: LCD

108, 112: CDS / AMP section 162: VRAM

109 and 113: A / D converter 164: SDRAM

110, 131: Image input controller 166: Media controller

120: DSP / CPU 168: recording media

121: timing generator

Claims (11)

A plurality of photoelectric conversion elements arranged in a two-dimensional direction and converting image light incident from a subject into an electrical signal; A readout unit configured to sequentially read the electrical signals of the photoelectric conversion elements in a device line including a plurality of the photoelectric conversion elements arranged along one direction; And The electrical signal of the first element line set comprising a plurality of the element lines parallel to each other, and the plurality of the element lines extending along the extension direction of the element lines of the first element line set and parallel to each other And a distance calculator for calculating a distance to the subject based on the difference in the intensity distribution of the electrical signals of the second element line set. The method of claim 1, The distance calculator is a straight line equal to the intensity distribution of the first element line, which is one of the element lines constituting the first element line set, and the first element line, among the element lines constituting the second element line set. And the distance is calculated by comparing the intensity distributions of the second element lines arranged on the image. The method of claim 1, The distance calculating unit may include the intensity distribution and the first distribution of the first element line set based on an added value obtained by adding an intensity of the electrical signal of the photoelectric conversion elements arranged along a direction crossing the extension direction of the element line. An imaging device, wherein the distance is calculated by comparing the intensity distributions of the two-element line sets. The method of claim 3, The number of the photoelectric conversion elements arranged along the direction crossing the direction of extension of the element line where the distance calculator adds the strength of the electrical signal to obtain the addition value is variable according to the brightness level of the image light of the subject, Imaging device. The method according to claim 3 or 4, The photoelectric conversion elements arranged along the direction transverse to the direction of extension of the device line, in which the distance calculator adds the strength of an electrical signal to obtain the addition value, may include the first device line set and the second device line set. And the photoelectric conversion elements so as not to overlap with each other. The method of claim 5, And the photoelectric conversion elements arranged along a direction crossing the extension direction of the device line for adding the electrical signal to the distance calculator to obtain the addition value are arranged on a straight line. The method of claim 6, And the plurality of photoelectric conversion elements are arranged in a matrix or honeycomb shape. The method of claim 1, And the first element line set and the second element line set can be selected by a user among the optical conversion elements. Sequentially reading the electrical signal for each of the photoelectric conversion elements from a device line in which a plurality of photoelectric conversion elements for converting image light incident from a subject into an electrical signal are arranged along one direction; And The electrical signal of the first device line set including the plurality of device lines parallel to each other, and the plurality of the device lines extending along the extension direction of the device lines of the first device line set and parallel to each other; Calculating a distance to the subject based on a difference in the intensity distribution of the electrical signals in the two-element line set. The method of claim 9, The calculating of the distance may include the intensity distribution of the first device line, which is one of the device lines constituting the first device line set, and the first device of the device lines constituting the second device line set. And the distance is calculated by comparing the intensity distributions of the second element lines arranged on the same straight line as the line. The method of claim 9, The calculating of the distance may include: the intensity distribution of the first set of device lines based on an added value obtained by adding an intensity of the electrical signal of the photoelectric conversion elements arranged along a direction crossing the extending direction of the device line And the intensity distribution of the second element line set to calculate the distance.

Images