JP4532849B2 - Automatic focusing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an automatic focusing device, and more particularly to an automatic focusing device used for an electronic still camera, a video camera, and the like.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in an electronic still camera, a video camera, and the like, an automatic focus detection device that performs a focusing operation by processing a high-frequency component of a luminance signal obtained from an image sensor such as a CCD is used. In this automatic focus detection device, it is generally performed to detect the focal point by detecting the lens position with the highest contrast by integrating the high-frequency component of the signal in the ranging area set in each screen. Yes.
[0003]
There has also been proposed an automatic focus detection apparatus that corrects a shift amount of a focus detection position caused by chromatic aberration of a focus detection light receiving sensor (see, for example, Patent Document 1). The apparatus includes a correction unit that calculates a correction value for correcting a detection error caused by chromatic aberration of the light receiving sensor for focus detection, and a focus detection unit that detects a focus adjustment state of the photographing lens, and the focus detection unit And the output of the correction unit are controlled to drive the photographic lens.
[0004]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2000-266988
[0005]
[Problems to be solved by the invention]
However, the conventional example has the following problems.
[0006]
(1) In the case of the integral type focus detection method, there is a problem that the in-focus position is not necessarily optimal due to the color and color temperature of the subject and the characteristics of the imaging optical system, particularly chromatic aberration. It was. In order to solve this, a method of selecting an optimal color pixel from the pixels of the image sensor used for focus detection based on the color information of the subject can be considered, but the applicable subject color is limited. However, since only a part of the pixels are used, the sampling becomes rough and there is a problem that it is not possible to deal with a subject having a high frequency component.
[0007]
(2) In Japanese Patent Laid-Open No. 2004-260688, correction is affected even to characteristics that are not inherent to the imaging optical system, including chromatic aberration of the optical system for collecting light to the light receiving sensor, so that the correction error is large, and the imaging element Since it is not a feedback system that uses its own signal, there is a problem that the mounting accuracy of the light receiving sensor itself affects the focusing accuracy. Furthermore, the correction of the shift amount due to the color temperature or color difference of the subject is not considered, and there is still room for improvement from the viewpoint of improving the focusing accuracy.
[0008]
SUMMARY OF THE INVENTION In view of the above-described conventional problems, an object of the present invention is to provide an automatic focusing device that realizes an improvement in focusing accuracy by enabling an optimum distance measuring method possessed by a subject to be performed in a feedback capable system. .
[0009]
[Means for Solving the Problems]
In order to achieve the above object, Focus An apparatus includes: an imaging element that receives a subject image formed through an imaging optical system including a focus lens unit, and receives light at two-dimensionally arranged R pixels, G pixels, and B pixels; The focus evaluation value from the high frequency components of the signals of the R pixel, the G pixel, and the B pixel arranged two-dimensionally on the light receiving surface corresponding to the AF area set on the photographing screen among the light receiving surfaces of the image sensor. An extraction means for extracting a signal, a focus position detection means for detecting a focus position with respect to the focus evaluation value signal extracted by the extraction means, and the subject image when the subject image that has passed through the imaging optical system is recorded. An image processing unit that calculates a luminance signal representing information of a high-definition portion using a signal obtained by reading only G pixels of the image sensor, and an alignment corresponding to the AF area based on detection information of the focus position detection unit. For the focal position, A predetermined amount corresponding to the difference between the spectral sensitivity characteristic of the extraction means and the spectral sensitivity of the image processing means, Color information in the AF area; Said Depending on the chromatic aberration information of the imaging optical system The Control means for controlling the focus lens driving means to drive the focus lens unit at a position shifted by a predetermined amount is provided.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0011]
[First Embodiment]
<Configuration of electronic camera>
FIG. 1 is a block diagram showing a configuration of an electronic camera applied to the automatic focusing apparatus according to the first embodiment of the present invention.
[0012]
In the figure, 201 is an imaging optical system, 202 is a diaphragm and shutter for controlling the amount of light, and 203 is a motor for moving the diaphragm and shutter. Reference numeral 204 denotes a mechanical drive circuit that drives the motor 203 to move the aperture and the shutter 202. Reference numeral 205 denotes a focus unit for focusing on an image sensor described later. 206 is a photo interrupter that detects the reset position of the focus unit 205, 207 is a motor that drives the focus unit 205, and 208 is a focus lens drive circuit that drives the motor 207 and causes the focus unit 205 to move the focus lens.
[0013]
Reference numeral 209 denotes an image sensor as a light receiving unit or a photoelectric conversion unit that converts reflected light from an object into an electric signal, 210 denotes a timing signal generation circuit that generates a timing signal necessary for operating the image sensor 209, and 211 denotes This is a pre-processing circuit including a CDS circuit that removes output noise of the image sensor 209 and a non-linear amplifier circuit that is performed before A / D conversion.
[0014]
212 is an A / D converter, 213 is a buffer memory, 214 is a memory controller that controls reading / writing of the memory 213 and DRAM refresh operation, and 215 is a system control CPU that controls the system such as a photographing sequence. Reference numeral 216 denotes an operation assist display and camera status display, an operation display section that displays a shooting screen and a distance measurement area at the time of shooting, 217 an operation section for operating the camera from the outside, and 218 an electric rewrite. Possible non-volatile memory (EEPROM).
[0015]
219 is an interface with an expansion unit to be described later, 220 is a detachable expansion unit that is connected to the electronic camera body to perform various processes and operations, 221 is an interface for connection with a recording medium to be described later, and 222 is a memory A recording medium such as a card or a hard disk, 223 is a main switch for turning on the system, 224 is a switch for performing a shooting standby operation such as AF or AE (hereinafter referred to as SW1), and 225 is a switch after the operation of SW1. An imaging switch (hereinafter referred to as SW2) that performs imaging, 226 is a mode switch that sets an imaging mode, 227 is a flash, and 228 is an auxiliary light source as a light projecting unit that uses an LED or the like as a light source.
[0016]
Reference numeral 229 denotes a color information detection unit that detects color information in the distance measurement area, obtains information on the color of the subject itself or the color temperature of the light source from the RGB values obtained from the video signal, and the color information and the imaging optical system 201. From the in-focus position detected by extracting the high-frequency component of the subject based on the characteristic information, it is finally determined how much the in-focus position should be shifted.
[0017]
<Pixel Configuration of Image Sensor 209>
FIG. 2 is a diagram illustrating an example of a pixel configuration of the image sensor 209.
[0018]
Here, the image sensor of FIG. 2A is configured such that pixels having spectral sensitivities of R (red), G (green), and B (blue) are shown in FIG. In the image pickup device shown in FIG. 2B, pixels having spectral sensitivities of M (magenta), G (green), C (cyan), and Y (yellow) are arranged as shown in FIG.
[0019]
A luminance signal representing information of a high-definition portion of an image photographed by these image sensors is obtained by using only the G pixel of FIG. A color difference signal obtained by performing matrix processing on a signal obtained by sequentially reading out pixels is used as a correction signal, and the correction signal is composed of a sum of the correction signal and a signal obtained by adding a certain ratio to a captured image.
[0020]
When the image sensor of FIG. 2B is used, a signal obtained by sequentially reading all the pixels in FIG. 2B and a color difference signal obtained by performing matrix processing on the signal obtained by sequentially reading all the pixels are used as correction signals. This correction signal is composed of a sum of a signal obtained by adding a certain ratio to the photographed image, and finally has a spectral sensitivity close to the visual sensitivity characteristic of the human eye as shown in FIG.
[0021]
On the other hand, the signal used to detect the in-focus position is a signal obtained by sequentially reading out all the pixels in any of the imaging elements shown in FIGS. 2A and 2B. In comparison, the sensitivity is higher than the luminance signal on the short wavelength side and the long wavelength side of the visibility region.
[0022]
As described above, in the automatic focusing apparatus according to the present embodiment, since there is an aberration of the imaging optical system 201 depending on the color within the distance measurement area of the subject, the position where the high frequency component of the signal used for focus position detection is maximized. The focus unit 205 is moved to a position that does not necessarily coincide with the position where the resolution of the luminance signal of the captured image is maximized and is shifted by an amount determined according to the characteristics of the imaging optical system 201. This shift amount is obtained by so-called chromatic aberration, in which the best focus position of the imaging optical system 201 differs depending on the wavelength of light from the subject, and also includes spherical aberration and off-axis coupling, which are imaging characteristics on the axis of the imaging optical system. It may take into account astigmatism and coma which are image characteristics.
[0023]
<Overall operation of automatic focusing device>
Hereinafter, the operation of the first embodiment will be described in detail with reference to FIG. FIG. 4 is a flowchart showing the overall operation of the automatic focusing apparatus according to this embodiment.
[0024]
First, in step S301, the state of the main switch 223 is detected. If it is on, the process proceeds to step S302. Here, the function of the main switch 223 is to turn on the system. In step S302, the remaining capacity of the recording medium 222 is checked. If the remaining capacity is sufficient for recording the subject, the process proceeds to step S304, and if not, the process proceeds to step S303.
[0025]
In step S303, a warning is given that the remaining capacity of the recording medium 222 is insufficient, and the process returns to step S301. The warning may be displayed on the operation display unit 216, a warning sound may be output from a sound output unit (not shown), or both. In step S304, the focus unit 205 is reset according to the flowchart of FIG.
[0026]
In the subsequent step S305, the distance measuring area in the shooting screen of the image sensor 209 is displayed. That is, the distance measuring area 501 that is set at the time of normal shooting and is located in the vicinity of the center in the shooting screen 500 shown by the broken line in FIG. 5 is stored in a calculation memory (not shown) built in the system control CPU 215 and the operation display unit. 216. In the next step S306, the state of the switch SW1 is checked. If the switch SW1 is on, the process proceeds to step S308. Otherwise, the process proceeds to step S307. Here, the function of the switch SW1 is to perform a photographing standby operation such as an automatic focus function (AF) or an automatic exposure function (AE). In step S307, the state of the main switch 223 is checked. If it is on, the process returns to step S305; otherwise, the process returns to step S301.
[0027]
In step S308, the subject luminance is calculated from the output signal of the image sensor 209. In step S309, the color information detection unit 229 uses the color information in the distance measurement area 501 and the image information of the image pickup optical system 201 from the output signal of the image sensor 209. From the in-focus position detected by extracting the high-frequency component of the subject by chromatic aberration or spherical aberration, it is finally determined how much the in-focus position should be shifted.
[0028]
In the subsequent AF operation of step S310, the AF operation is performed according to the flowchart of FIG. 8 described later using the shift amount obtained in step S309. At this time, if the subject brightness is lower than a predetermined value, the auxiliary light source 228 is projected toward the subject for a predetermined time. In step S311, the state of SW2 is checked, and if it is on, the process proceeds to step S313, and if not, the process proceeds to step S312. Here, the function of SW2 is to perform photographing after operation of SW1. In step S312, the state of SW1 is checked. If it is on, the process returns to step S311; otherwise, the process returns to step S305. In step S313, a photographing operation is performed according to the flowchart of FIG. In step S314, the remaining capacity of the recording medium 222 is checked. If the remaining capacity is sufficient to record the subject, the process proceeds to step S315. If not, the process proceeds to step S303. In step S315, the state of SW2 is checked and turned on. Otherwise, the process proceeds to step S312.
[0029]
<Reset focus lens>
Next, the focus lens reset operation in step S304 in FIG. 4 will be described with reference to the flowchart in FIG. FIG. 6 is a flowchart showing processing of the focus lens reset operation (step S304) in FIG. In this description, the relationship between the position of the photo interrupter 206 and the output is as shown in FIG. 7, and when the focus unit 205 is on the infinite end side with respect to the photo interrupter output switching position, the output of the photo interrupter 206 is “Lo”. When it is at the closest end, it is assumed to be “Hi”.
[0030]
First, in step S501, the output state of the photo interrupter 206 is checked. If “Lo”, the process proceeds to step S502, and if not, the process proceeds to step S503. In the next step S502, the focus unit 205 is determined to be on the infinite end side with respect to the photointerrupter output switching position by the output of the photointerrupter 206 in step S501. Therefore, the focus unit 205 is moved one step toward the closest end side. To do.
[0031]
In step S503, the output state of the photo interrupter 206 is checked. If “Hi”, the process proceeds to step S504, and if not, the process proceeds to step S505. In step S504, since it is determined that the focus lens 205 is on the near end side with respect to the photo interrupter output switching position based on the output of the photo interrupter 206 in step S503, the focus unit 205 is moved one step toward the infinite end side.
[0032]
<Operation of Focus Unit 205>
Next, the operation of the focus unit 205 after resetting the focus lens as described above will be described.
[0033]
First, when the position of the focus unit 205 when the main switch 223 is turned on is on the infinite end side with respect to the photointerrupter output switching position, the output of the photointerrupter 206 is “Lo”. By S501 and S502, the focus unit 205 is moved step by step toward the closest end until the output of the photo interrupter 206 becomes “Hi”.
[0034]
Since the output of the photointerrupter 206 is switched to “Hi” when the photointerrupter output switching position in FIG. Moved one step at a time.
[0035]
Thus, the focus unit 205 finally stops at the reset position in FIG.
[0036]
When the position of the focus unit 205 when the main switch 223 is turned on is close to the photo interrupter output switching position, the focus unit 205 is moved only to the infinite end side to output the photo interrupter 206. Stop when “Lo” is reached.
[0037]
Thus, as in the case where the position of the focus unit 205 when the main switch 223 is turned on is on the infinite end side with respect to the photo interrupter output switching position, the focus unit 205 is finally reset as shown in FIG. Stop in position.
[0038]
<AF Operation of First Embodiment>
Hereinafter, the AF operation subroutine of step S310 of FIG. 4 will be described with reference to the flowchart of FIG.
[0039]
This AF operation is performed by peak detection of a high frequency component (hereinafter referred to as a focus evaluation value) of a signal obtained from the image sensor 209.
[0040]
First, in step S601, the focus unit 205 is moved to the scan start position. Here, it is assumed that the scan start position is set to an infinite end in the distance measurement range. In subsequent step S602, the focus evaluation value of the distance measurement area stored in step S305 and the position of the focus unit 205 are stored. When the stepping motor is used as the focus lens drive motor 207, the position of the focus unit 205 is detected as a relative position from the reset position detected by the photo interrupter 206 for reset position detection.
[0041]
In step S603, it is checked whether or not the lens position is at the end position. If it is the end position, the process proceeds to step S607, and if not, the process proceeds to step S604. Here, the scan end position is set to the closest end in the distance measurement range. In step S604, the focus unit 205 is driven and moved in the closest direction by a predetermined amount.
[0042]
In subsequent step S607, the focus unit 205 is moved from the position where the focus evaluation value shows the maximum value in step S602 to a position moved by the predetermined shift amount obtained in S309 by the color information detection unit 229.
[0043]
<Details of shooting operation>
Next, a subroutine for the photographing operation in step S313 in FIG. 4 will be described with reference to the flowchart in FIG.
[0044]
FIG. 9 is a flowchart showing a subroutine of the photographing operation (step S313) in FIG.
[0045]
First, in step S701, the subject brightness is measured, and in the next step 702, the image sensor 209 is exposed according to the subject brightness measured in step S701. In subsequent step S703, the preprocessing circuit 211 performs output noise removal of the image sensor 209, non-linear processing performed before A / D conversion, and the like. In step S704, the analog signal from the preprocessing circuit 211 is converted into a digital signal. Convert to
[0046]
In subsequent step S705, the output data from the A / D converter 212 is temporarily stored in the buffer memory 213 via the memory controller 214, and in step S706, the data in the buffer memory 213 is stored in the memory controller 214. The data is transferred to the recording medium 222 such as a memory card attached to the camera body via the recording interface 221.
[0047]
As described above, in the present embodiment, the optimum measurement is performed for each zoom position, aperture value, focus position, and subject color temperature of the imaging optical system based on the color information in the distance measurement area of the subject and the characteristic information of the imaging optical system. A distance method can be performed.
[0048]
[Second Embodiment]
Hereinafter, the case where an electronic camera is applied to the second embodiment of the automatic focusing apparatus of the present invention will be described with reference to FIGS. 10 and 11 as in the first embodiment.
[0049]
An area 501 a indicated by a broken line in FIG. 10 is stored as a distance measurement area in the CPU 215 and displayed on the operation display unit 216. FIG. 10 is a diagram showing a distance measurement area during normal shooting of the automatic focusing apparatus according to the second embodiment of the present invention.
[0050]
As in the present embodiment, since there are a plurality of distance measuring areas 501a, the main subject can be focused without taking steps such as AF lock even if the main subject is not at the center of the shooting screen, and instant shooting is possible. Can be provided. The automatic focusing apparatus of the second embodiment also performs overall control according to the flowchart of FIG. 4, but the description of the portion that performs the same operation as that of the first embodiment is omitted.
[0051]
In step S305 of FIG. 4, the distance measurement areas in the shooting screen of the image sensor 209 are stored in a calculation memory (not shown) built in the system control CPU 215 as a plurality of distance measurement areas 501a as indicated by broken lines in FIG. It is stored and displayed on the operation display unit 216.
[0052]
In step S309, the color information detection unit 229 determines how much the focus position should be shifted finally. That is, the color information in each ranging area 501a on the imaging surface and the chromatic aberration of the imaging optical system 201 or the spherical aberration or non-axis imaging characteristics corresponding to the chromatic aberration or the angle of view of each ranging area 501a. From the in-focus position detected by extracting the high-frequency component of the subject based on the point aberration and coma aberration, it is finally determined how much the in-focus position should be shifted.
[0053]
<AF Operation of Second Embodiment>
In the AF operation of step S310, the AF operation is performed according to the flowchart of FIG. 11 using the shift amount obtained in step S309.
[0054]
More specifically, first, in step S901, the focus unit 205 is moved to the scan start position. Here, it is assumed that the scan start position is set to an infinite end in the distance measurement range. In the subsequent step S902, the focus evaluation values and the positions of the focus units 205 for all the ranging areas 501a stored in step S305 are stored. When the focus lens drive motor 207 uses a stepping motor, the position of the focus unit 205 is detected as a relative position from the reset position detected by the reset position detection photo interrupter 206.
[0055]
Next, in step S903, it is checked whether or not the lens position is at the end position. If it is the end position, the process proceeds to step S905. Otherwise, the process proceeds to step S904. Here, the scan end position is set to the closest end in the distance measurement range.
[0056]
In step S904, the focus unit 205 is driven and moved by a predetermined amount in the closest direction. In step S905, the maximum focus evaluation value stored in step S902 is obtained for each of the plurality of distance measurement areas 501a. Extract position. In the next step S906, for the plurality of distance measurement areas 501a stored in step S305, the distance measurement area to be focused is preset based on the combination of the maximum focus evaluation value obtained in step S905 and the lens position thereof. Select by calculation.
[0057]
In step S907, the position moved by the predetermined shift amount obtained in step S309 by the color information detection unit 229 from the position where the focus evaluation value shows the maximum value in the distance measurement area selected in step S906. The focus unit 205 is moved to.
[0058]
As described above, even when there are a plurality of ranging areas as in the present embodiment, by obtaining color information from the subject and characteristic information of the imaging optical system, the zoom position, aperture value, focus position, and An optimum distance measuring method can be performed for each color temperature of the subject.
[0059]
Note that the above-described control method can be realized by storing and operating the program according to the flowcharts of FIGS. 4, 6, 8, and 9 described above in, for example, the EEPROM 218.
[0060]
The present invention is not limited to the apparatus of the above-described embodiment, and may be applied to a system composed of a plurality of devices or an apparatus composed of a single device. A storage medium storing software program codes for realizing the functions of the above-described embodiments is supplied to a system or apparatus, and a computer (or CPU or MPU) of the system or apparatus reads and executes the program codes stored in the storage medium. Needless to say, it will be completed by doing.
[0061]
In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention. As a storage medium for supplying the program code, for example, a floppy (registered trademark) disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD-R, magnetic tape, nonvolatile memory card, ROM is used. Can do. In addition, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also the OS running on the computer based on the instruction of the program code performs the actual processing. It goes without saying that a case where the functions of the above-described embodiment are realized by performing part or all of the processing, is also included.
[0062]
Furthermore, after the program code read from the storage medium is written to the memory provided in the function expansion board inserted in the computer or the function expansion unit connected to the computer, the program code is expanded based on the instruction of the next program code. It goes without saying that the functions of the embodiment described above are realized by performing some or all of the actual processing by the CPU or the like provided on the expansion board or expansion unit.
[Embodiment]
Examples of embodiments of the present invention are listed below.
[0063]
<Embodiment 1> A focus lens that adjusts the focus of a subject image, a focus lens driving unit that drives the focus lens, an image sensor that receives a subject image formed by the focus lens and converts it into an electrical signal, and Extracting means for extracting a signal indicating a high-frequency component of a subject from a signal of a light receiving surface corresponding to a distance measuring area set on a photographing screen among light receiving surfaces of the image sensor; and color information of the distance measuring area Based on detection information of the focus position detection means, color position detection means for detecting a focus position with respect to the signal extracted by the extraction means, and the distance measurement area The focus lens is shifted to a focus position corresponding to a predetermined amount determined by detection information of the color information detection means and / or characteristic information of the focus lens. And a control means for controlling the focus lens driving means so as to drive the lens.
[0064]
<Embodiment 1 The automatic focusing device according to Embodiment 1, wherein the setting of the shift amount is changed for each color temperature of the distance measurement area.
[0065]
<Embodiment 2 The automatic focusing device according to claim 1, wherein the shift amount setting is changed for each saturation or hue of the distance measurement area.
[0066]
<Embodiment 3 The automatic focusing device according to the first embodiment, wherein the setting of the shift amount is changed for each zoom position of the focus lens.
[0067]
<Embodiment 4 The automatic focusing device according to Embodiment 1, wherein the shift amount setting is changed for each aperture value of the focus lens.
[0068]
<Embodiment 5 The automatic focusing device according to Embodiment 1, wherein the shift amount setting is changed for each focus position of the focus lens.
[0069]
<Embodiment 7> A focus lens that adjusts the focus of a subject image, a focus lens driving unit that drives the focus lens, and an imaging device that receives a subject image formed by the focus lens and converts it into an electrical signal Extraction means for extracting a signal indicating a high-frequency component of the subject from each signal of the light receiving surface corresponding to each of a plurality of distance measurement areas set on the photographing screen among the light receiving surfaces of the image sensor; Color information detection means for detecting color information in the distance measurement area, focus position detection means for detecting a focus position for each signal extracted by the extraction means, and detection by the focus position detection means Based on the information, a focusing area selecting means for selecting a focusing area to be focused, and a focusing position corresponding to the ranging area selected by the focusing area selecting means Control means for controlling the focus lens driving means to drive the focus lens at a position shifted by a predetermined amount determined by detection information of the color information detecting means and / or characteristic information of the focus lens. Automatic focusing device characterized by
[0070]
<Embodiment 8> The automatic focusing device according to Embodiment 7, wherein the shift amount setting is changed for each of the distance measurement areas for each color temperature of the distance measurement area.
[0071]
<Embodiment 9> The automatic focusing device according to Embodiment 7, wherein the shift amount setting is changed for each of the distance measurement areas for each saturation or hue of the distance measurement area.
[0072]
<Embodiment 10> The automatic focusing device according to Embodiment 7, wherein the shift amount setting is changed for each zooming position of the focus lens for each distance measurement area.
[0073]
<Embodiment 11> The automatic focusing device according to embodiment 7, wherein the shift amount setting is changed for each aperture area of the focus lens for each aperture value.
[0074]
<Embodiment 12> The automatic focusing device according to Embodiment 7, wherein the shift amount setting is changed for each focus area of the focus lens with respect to each distance measurement area.
[0075]
<Embodiment 13> A focus lens for adjusting the focus of a subject image, focus lens driving means for driving the focus lens, an image sensor for receiving a subject image formed by the focus lens and converting it into an electrical signal, and In the control method of the automatic focusing apparatus having the above, in the light receiving surface of the image sensor, extraction is performed to extract a signal indicating a high-frequency component of the subject from the signal of the light receiving surface corresponding to the distance measurement area set on the shooting screen Performing a step, a color information detection step for detecting color information of the distance measurement area, and a focus position detection step for detecting a focus position for the signal extracted in the extraction step, and the focus position Based on the detection information of the detection process, the in-focus position corresponding to the ranging area is determined by the detection information of the color information detection process and / or the characteristic information of the focus lens. A control method for an automatic focusing device, wherein the focus lens driving means is controlled to drive the focus lens at a position shifted by a predetermined amount.
[0076]
<Embodiment 14> A focus lens for adjusting the focus of a subject image, focus lens driving means for driving the focus lens, an image sensor for receiving a subject image formed by the focus lens and converting it into an electrical signal, In the control method of the automatic focusing device, the signal indicating the high frequency component of the subject from each signal of the light receiving surface corresponding to each of the plurality of distance measuring areas set on the photographing screen among the light receiving surfaces of the image sensor An extraction process for extracting each of the distance measurement areas, a color information detection process for detecting the color information of each distance measuring area, and a focus position detection process for detecting the focus position for each signal extracted in the extraction process. And a focus area selection step for selecting a distance measurement area to be focused on the basis of the detection information of the focus position detection process, according to the focus area selection process. The focus lens is driven to a position shifted by a predetermined amount determined by the detection information of the color information detection process and / or the characteristic information of the focus lens with respect to the focus position corresponding to the selected ranging area. As described above, the focus lens driving means is controlled as described above.
[0077]
<Embodiment 15> A focus lens that adjusts the focus of a subject image, a focus lens driving unit that drives the focus lens, an image sensor that receives a subject image formed by the focus lens and converts the subject image into an electrical signal, and A medium for providing a control program for executing a control method of an automatic focusing device having a distance between a light receiving surface of the image sensor and a distance measurement area set on a photographing screen. An extraction step of extracting a signal indicating a high-frequency component of the subject from a signal of the light receiving surface, a color information detection step of detecting color information of the distance measuring area, and focusing on the signal extracted in the extraction step Based on the focus position detection step for detecting the position and the detection information of the focus position detection step, with respect to the focus position corresponding to the distance measurement area, A step of controlling the focus lens driving means to drive the focus lens at a position shifted by a predetermined amount determined by detection information of the color information detection step and / or characteristic information of the focus lens. A medium that provides a characteristic control program.
[0078]
<Embodiment 16> A focus lens that adjusts the focus of a subject image, a focus lens driving unit that drives the focus lens, an image sensor that receives a subject image formed by the focus lens and converts it into an electrical signal, and A medium for providing a control program for executing a control method of an automatic focusing device having a plurality of ranging areas set on a photographing screen among light receiving surfaces of the image sensor The extraction step for extracting a signal indicating the high-frequency component of the subject from each signal on the light receiving surface corresponding to each of the signals, the color information detection step for detecting the color information of each distance measuring area, and the extraction step, respectively. An in-focus position detecting step for detecting the in-focus position for each signal, and detection information of the in-focus position detecting step. A focus area selection step for selecting a distance measurement area to be focused, and detection information of the color information detection step for a focus position corresponding to the distance measurement area selected in the focus area selection step; A medium for providing a control program comprising the step of controlling the focus lens driving means so as to drive the focus lens at a position shifted by a predetermined amount determined by characteristic information of the focus lens .
[0079]
<Embodiment 6 > Automatic focusing comprising a focus lens for adjusting the focus of the subject image, a focus lens driving means for driving the focus lens, and an image sensor for receiving the subject image formed by the focus lens and converting it into an electrical signal. A control program for executing a control method of a focusing device, which indicates a high-frequency component of a subject from a signal of a light receiving surface corresponding to a ranging area set on a photographing screen among light receiving surfaces of the image sensor An extraction step for extracting a signal; a color information detection step for detecting color information of the distance measurement area; a focus position detection step for detecting a focus position with respect to the signal extracted in the extraction step; Based on the detection information in the focus position detection step, the detection information in the color information detection step and / or the photo for the in-focus position corresponding to the ranging area. A control program comprising a step of controlling the focus lens driving means so as to drive the focus lens at a position shifted by a predetermined amount determined by the characteristic information of the focus lens.
[0080]
<Embodiment 7 > Automatic focusing comprising a focus lens for adjusting the focus of the subject image, a focus lens driving means for driving the focus lens, and an image sensor for receiving the subject image formed by the focus lens and converting it into an electrical signal. A medium for providing a control program for executing a control method for a focusing device, wherein each signal of a light receiving surface corresponding to each of a plurality of ranging areas set on a photographing screen among light receiving surfaces of the image sensor An extraction step for extracting a signal indicating a high-frequency component of the subject, a color information detection step for detecting color information of each distance measurement area, and a focus on each signal extracted in the extraction step. An in-focus position detecting step for detecting a position, and an in-focus distance detection area to be selected based on detection information in the in-focus position detecting step. A predetermined amount determined by the detection information of the color information detection step and / or the characteristic information of the focus lens with respect to the focus position corresponding to the focus area selection step and the focus detection area selected by the focus area selection step A control program comprising a step of controlling the focus lens driving means so as to drive the focus lens at a position shifted by a distance.
[0081]
【The invention's effect】
As described above, according to the present invention, the optimum distance measuring method possessed by the subject can be executed by a system capable of feedback, and it is possible to improve the focusing accuracy.
[Brief description of the drawings]
FIG. 1 is a configuration block diagram of an electronic camera to which the present invention is applied.
FIG. 2 is a diagram illustrating an example of a pixel configuration of an image sensor.
FIG. 3 is a diagram illustrating visibility characteristics of human eyes.
FIG. 4 is a flowchart showing the overall operation of the first embodiment.
FIG. 5 is a diagram illustrating a ranging area according to the first embodiment.
FIG. 6 is a flowchart showing a reset operation of the focus lens.
FIG. 7 is a diagram illustrating a relationship between a position of a photo interrupter and an output.
FIG. 8 is a flowchart showing an AF operation according to the first embodiment.
FIG. 9 is a flowchart showing a photographing operation.
FIG. 10 is a diagram showing a distance measurement area according to a second embodiment of the present invention.
FIG. 11 is a flowchart showing an AF operation according to the second embodiment.
[Explanation of symbols]
201 Imaging optical system
202 Aperture and shutter
203 motor
204 Mechanical drive circuit
205 Focus unit
206 Photointerrupter
207 motor
208 Focus lens drive circuit
209 Image sensor
210 Timing signal processing circuit
211 Pre-processing circuit
212 A / D converter
213 Buffer memory
214 Memory controller
215 Microcontroller
216 Operation display section
217 operation unit
218 Nonvolatile memory
219 interface
220 Expansion unit
221 interface
222 Recording medium
223 Main switch
224 switch
225 Shooting switch
226 Mode switch
227 flash
228 Auxiliary light source
229 color information detector

Claims (6)

An image sensor that receives a subject image formed through an imaging optical system including a focus lens unit and receives the light at two-dimensionally arranged R, G, and B pixels, and converts the received image into an electrical signal;
A focus evaluation value signal is obtained from high-frequency components of R pixel, G pixel, and B pixel signals arranged two-dimensionally on the light receiving surface corresponding to the AF area set on the photographing screen among the light receiving surfaces of the image sensor. Extracting means for extracting
A focus position detection means for detecting a focus position with respect to the focus evaluation value signal extracted by the extraction means;
Image processing means for calculating a luminance signal representing information of a high-definition portion using a signal obtained by reading only G pixels of the image sensor when recording a subject image that has passed through the imaging optical system;
Based on the detection information of the in-focus position detecting means, the in-focus position corresponding to the AF area is in accordance with the difference between the spectral sensitivity characteristic in the extracting means and the spectral sensitivity in the image processing means. a predetermined amount, a predetermined amount shifted by a position corresponding to the chromatic aberration information of the imaging optical system and the color information of the AF area, controls the focus lens drive means to drive the focus lens unit And an automatic focusing device.   2. The automatic focusing device according to claim 1, wherein the shift amount setting is changed for each color temperature of the AF area.   2. The automatic focusing apparatus according to claim 1, wherein the shift amount setting is changed for each saturation or hue of the AF area.   The automatic focusing device according to claim 1, wherein the setting of the shift amount is changed for each zoom position of the focus lens.   The automatic focusing device according to claim 1, wherein the setting of the shift amount is changed for each aperture value of the focus lens.   The automatic focusing device according to claim 1, wherein the setting of the shift amount is changed for each focus position of the focus lens.

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