JP2004219581A - Automatic focusing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize the speeding-up of focusing that a photographing condition is optimized especially by preventing focusing speed from lowering while improving focusing accuracy. <P>SOLUTION: The automatic focusing device obtaining the evaluated values of both of phase difference autofocus and contrast detecting autofocus is equipped with a 1st focusing means for coarse adjustment 6 and a 2nd focusing means for fine adjustment 4, and obtains the circle of confusion from the focal length and the diaphragm value of a lens at the time of photographing. When comparing the obtained circle of confusion with an allowable circle of confusion and judging that fine adjustment is not required, only coarse adjustment operation that a target adjusting position is obtained by the phase difference autofocus is performed, and fine adjustment operation for final focusing is not performed, so that the focusing speed is made higher. Thus, a 1st state where focusing is performed only by the focusing means for coarse adjustment and a 2nd state where focusing is performed by combining the focusing means for coarse adjustment and the focusing means for fine adjustment are selected, so that the fine adjustment is performed only when it is required, and the focusing speed is made higher. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an automatic focusing device used for an imaging device in a digital still camera, a video camera, and the like.
[0002]
[Prior art]
Conventionally, a TTL phase difference autofocus or the like has been used as an autofocus mechanism of an interchangeable lens type autofocus single-lens reflex camera using a silver halide film. In this autofocus mechanism, a defocus detection mechanism for autofocus is provided in the camera body, and the focus adjustment lens of the interchangeable lens performs a focus adjustment operation by a motor in the lens or the camera.
[0003]
In a video camera or the like, a so-called hill-climbing servo autofocus that performs contrast detection based on a high-frequency component of a signal from an image sensor is performed.
[0004]
The TTL phase difference autofocus and the contrast detection autofocus each have characteristics, and are used properly depending on the application.
[0005]
According to Patent Literature 1, the contrast detection autofocus and the TTL phase difference autofocus are performed in combination because the defocus direction and the defocus amount cannot be known by one focus detection only by the contrast detection autofocus. The technology is disclosed.
[0006]
Patent Literature 2 discloses a technique for changing a focus determination range depending on a difference in a depth of focus range or a depth of field range.
[0007]
[Patent Document 1]
JP-A-5-64056
[Patent Document 2]
JP-A-55-48737
[0008]
[Problems to be solved by the invention]
However, the conventional example has the following disadvantages, and it has been difficult to increase the focusing speed. In the conventional examples disclosed in Patent Literatures 1 and 2, in order to increase the final precision of the focus adjustment, it is necessary to make the resolution of the focus position adjustment sufficiently fine. For that purpose, the focus adjustment mechanism must be finely controlled. However, there is a problem that the speed for adjustment is necessarily sacrificed and the adjustment speed is reduced.
[0009]
The present invention has been made to solve such a conventional problem, and prevents a decrease in the adjustment speed while improving the focusing accuracy, and in particular, a high-speed focusing adjustment optimized for shooting conditions. For the purpose of
[0010]
[Means for Solving the Problems]
The automatic focus adjustment device of the present invention includes an evaluation value acquisition unit that obtains an evaluation value of phase difference autofocus, an evaluation value acquisition unit that obtains an evaluation value of contrast detection autofocus, a focus adjustment unit for coarse adjustment, and a fine adjustment. A first state in which focus adjustment means and focus adjustment are performed only by the coarse adjustment focus adjustment means, and a second state in which the coarse adjustment focus adjustment means and the fine adjustment focus adjustment means are combined are selected. And a selecting means for performing the selection.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First Embodiment)
FIG. 1 is a diagram showing the configuration of the automatic focusing apparatus according to the first embodiment, which is an example in which the present invention is applied to a digital still camera of an interchangeable lens type, in which both a coarse adjustment actuator and a fine adjustment actuator are mounted on an interchangeable lens. ing.
[0012]
In FIG. 1, 1 is a digital still camera main body, and 2 is an interchangeable lens. The interchangeable lens 2 includes a focus lens 3, and the focus is adjusted by the focus lens 3.
[0013]
Reference numeral 4 denotes second focus adjusting means for adjusting the focus lens 3 in the optical axis direction. The second focus adjustment means 4 functions as a fine adjustment actuator. The focus lens 3 and the second focus adjusting means 4 are held by a focus lens barrel 5. The focus lens 3 is adjusted relative to the focus lens barrel 5 in the optical axis direction by the second focus adjusting means 4. Further, the second focus adjusting means 4 has a position encoder indicating a relative positional relationship between the focus lens barrel 5 and the focus lens 3.
[0014]
Reference numeral 6 denotes first focus adjusting means for adjusting the focus lens barrel 5 in the optical axis direction. The first focus adjusting means 6 functions as a coarse adjustment actuator.
[0015]
In the configuration described above, the focus lens 3 can be adjusted by any of the first and second focus adjusting means 6 and 4. In the present embodiment, the first focus adjustment means 6 is for coarse adjustment, and the second focus adjustment means 4 is for fine adjustment.
[0016]
Reference numeral 7 denotes a lens control circuit, which communicates with the digital still camera main body 1 and controls the first focus adjustment means 6 and the second focus adjustment means 4.
[0017]
Reference numeral 8 denotes a half mirror, 9 denotes an image sensor, and 10 denotes a phase difference AF sensor. The half mirror 8 divides the photographic light beam into the image sensor 9 and the phase difference AF sensor 10. With this configuration, the imaging operation and the phase difference AF detection operation can be performed simultaneously.
[0018]
An LCD panel 11 for an electronic viewfinder has a built-in backlight. Reference numeral 12 denotes a finder optical system. With this configuration, the LCD panel 11 is observed through the finder optical system 12.
[0019]
Reference numeral 13 denotes first focus evaluation means, which calculates a defocus amount from an output of the phase difference AF sensor 10.
[0020]
Reference numeral 14 denotes an image processing unit that processes an output signal of the image sensor 9 to extract contrast information of the image, performs white balance, γ processing, color matrix processing, and the like to form a captured image and an image for a finder. The image for the finder formed by the image processing means 14 is sent to the LCD panel 11, and the image for the finder displayed on the LCD panel 11 is observed via the finder optical system 12.
[0021]
Reference numeral 15 denotes a second focus evaluation unit that outputs a focus evaluation value by determining the history of contrast information obtained from the image processing unit 14.
[0022]
A camera control circuit 16 controls the entire digital still camera body 1.
[0023]
Reference numeral 17 denotes a lens interface circuit that exchanges signals with the lens control circuit 7 of the interchangeable lens 2.
[0024]
Reference numeral 18 denotes a release switch, which has a two-stage switch configuration. Reference numeral 19 denotes an exposure mode setting means, which is constituted by a rotary switch. The exposure mode setting means 19 has each exposure mode of program P, aperture priority Av, shutter speed priority Tv, and manual M as shown in FIG.
[0025]
Reference numeral 20 denotes a main electronic dial, and reference numeral 21 denotes a sub electronic dial. Both dials 20 and 21 are configured to detect the amount of rotation by endless rotation. The functions of the main electronic dial 20 and the sub electronic dial 21 are shown in FIG. As shown in the figure, the exposure modes are different.
[0026]
The image photographed by the digital still camera described above is stored in a non-volatile memory (not shown) or the like.
[0027]
Hereinafter, the control accuracy of the first focus adjustment unit 6 and the second focus adjustment unit 4 will be described. As described above, the first focus adjustment means 6 serves for coarse adjustment, and the second focus adjustment means 4 serves for fine adjustment.
[0028]
The specifications related to the accuracy in the present embodiment are as follows.
Image sensor size: 24mm long, 36mm wide
Pixel pitch: 5 μm
Effective pixels: 3.456 million pixels (4800 * 7200 Pixel)
Pixel configuration: RGB Bayer array
EVF pixel configuration: 300 * 450 * RGB Pixel
EVF mode reading ・ ・ ・ 1/16 thinned out both vertically and horizontally
EVF allowable circle of confusion: 100 μm
Coarse confusion circle diameter 35 μm
Fine adjustment permissible circle of confusion: 10 μm
[0029]
Here, the coarse adjustment permissible circle of confusion is determined under the condition that an image is printed out in a cabinet size and viewed at a clear viewing distance.
[0030]
The EVF allowable circle of confusion diameter and the fine-adjustment circle of confusion are determined to be twice the sampling interval according to the sampling theorem.
[0031]
The diameter of the permissible circle of confusion at the time of fine adjustment corresponds to an application in which a captured image is enlarged to a size equal to or greater than a pixel to confirm the image.
[0032]
In order to achieve the confusion circle diameter, the following relationship is satisfied. The control pitch of the first focus adjusting means 6 is controlled at ＊* F * 35 μm, where F is the open Fno. It is. The detection accuracy of the phase difference AF is also set to ＊* F * 35 μm or less. The control pitch of the second focus adjusting means 4 is 1/2 * F * 10 [mu] m. In the present embodiment, the second focus adjusting means 4 is mounted on the interchangeable lens 2 side. However, when the second focus adjusting means 4 is mounted on the camera body 1 side, it can be set to a fixed value such as ＊* 1 * 10 μm. good.
[0033]
Next, the processing operation of the digital still camera according to the present embodiment will be described with reference to the flowcharts of FIGS. When a power supply (not shown) is turned on, the process starts from step S101.
[0034]
In step S101, the camera control circuit 16 starts an initialization operation and sends a command for initial reset to the lens control circuit 7 via the lens interface circuit 17. Upon receiving the initial reset command, the lens control circuit 7 moves the focus lens 3 to a predetermined position of the focus lens barrel 5, for example, the center position by the second focus adjusting means 4.
[0035]
In step S102, the fact that the fine adjustment position is the center is stored. As a modified example, it may be stored in the form of a fine adjustment range in the forward direction and the reverse direction.
[0036]
In step S103, the drive of the image sensor 9 is started, and the EVF display is started by processing the image signal of the image sensor 9 by the image processing means 14 and displaying it on the LCD panel 11.
[0037]
In step S104, shooting information of the camera is displayed so as to overlap the finder image on the LCD panel 11. As the photographing information displayed here, of the photographing mode, the set shutter speed, the aperture value, and the exposure correction information, the information which is determined at that time is displayed.
[0038]
In step S105, if Sw1 as the first-stage switch of the release switch 18 is on, the process proceeds to step S120 in the flowchart of FIG. 5, and if it is off, the process proceeds to step S106.
[0039]
In step S106, if the exposure mode setting means 19 has been changed, the process proceeds to step S161 in the flowchart of FIG. 6, and if not, the process proceeds to step S107.
[0040]
In step S107, if the main electronic dial 20 is rotating, the process proceeds to step S171 in the flowchart of FIG. 7, and if not, the process proceeds to step S108.
[0041]
In step S108, if the sub electronic dial 21 is rotating, the process returns to step S175 in the flowchart of FIG. 8, and if not, the process returns to step S105.
[0042]
In the loop of steps S105 to S108, a change in the state of the operation member is monitored.
[0043]
From step S120 in FIG. 5, the flow from AF to shooting after the release switch is half-pressed is shown. In step S120, the stored fine adjustment position is obtained, and the movable range in the infinite / closest direction is calculated. The movable range obtained here is defined as Xinf (infinite direction) and Xnear (closest direction).
[0044]
In step S121, a signal is obtained from the phase difference AF sensor 10, and the first focus evaluation unit 13 calculates a defocus amount.
[0045]
In step S122, based on the obtained defocus amount, if the first focus adjustment unit 6 and the second focus adjustment unit 4 are to be independently performed to bring the defocus amount into a focused state, how much driving is required Is calculated. The drive amount of the first focus adjustment unit 6 is X1, and the drive amount of the second focus adjustment unit 4 is X2.
[0046]
In step S123, if the drive amount X1 is within the rough adjustment target range and the drive amount X2 is within the following conditions, the process proceeds to step S130. If not, the process proceeds to step S124. Here, the coarse adjustment target range is the open Fno. * 35 μm is set as a reference, and at the same time, is determined based on a circle of confusion that can be confirmed by an EVF as a finder. As a result, the EVF is recognized as being in focus at the coarse adjustment stage, and sufficient accuracy can be obtained in a printout evaluation other than for an application in which a personal computer or the like enlarges the image to one-to-one size or more.
[0047]
The condition of the drive amount X2 is such that the estimated error amount Xd of the phase difference AF and the contrast AF peak confirmation amount Xaf are added to the required drive amount X2 of the second focus adjustment unit 4 calculated in step S122, and the values are used as the movable range Xinf. Alternatively, it is determined whether focusing can be performed reliably within the fine adjustment possible range in comparison with Xnear.
When the value of X2 is in the infinite direction, (X1 + Xd + Xaf) <Xinf
When the value of X2 is in the closest direction, (X1 + Xd + Xaf) <Xnear
[0048]
In step S124, the drive amount of X1 is corrected by the difference between the reset position of the second focus adjustment unit 4 and the current position. The final drive amount obtained here is defined as X1 '.
[0049]
In step S125, the final drive amount X1 'is sent to the lens control circuit 7. The lens control circuit 7 starts driving the focus lens barrel 5 by the first focus adjusting means 6.
[0050]
In step S126, if the second focus adjustment means 4 for fine adjustment is at the reset position, the process proceeds to step S129, and if not, the process proceeds to step S127.
[0051]
In step S127, an instruction for initial reset is sent to the lens control circuit 7 via the lens interface circuit 17. The lens control circuit 7 that has received the initial reset command moves the focus lens 3 to a predetermined position of the focus lens barrel 5 by the second focus adjustment means 4. With the above operation, the reset operation of the focus lens 3 to the predetermined position of the focus lens barrel 5 is performed in parallel while the focus lens barrel 5 is being driven. Further, since the final drive amount X1 'of the focus lens barrel 5 takes into account the movement amount of the focus lens 3 due to the reset operation, it is possible to prevent the drive amount from becoming inappropriate due to the reset operation. In step S128, the fact that the fine adjustment position is the center is stored.
[0052]
In step S129, if the driving of the final driving amount X1 'is completed, the process returns to step S121, and if not, the process returns to step S129. The rough adjustment of the focusing operation is completed in the loop of steps S121 to S129.
[0053]
In step S130, if the exposure mode is manual, the process proceeds to step S133; otherwise, the process proceeds to step S131.
[0054]
In step S131, photometry is performed from an image signal obtained from the image sensor 9, and automatic exposure calculation is performed in an exposure mode selected from among P, Tv, and Av. Here, the combination of the shutter speed and the aperture value is determined. In step S132, the combination of the shutter speed and the aperture value is determined. After the determination, the process proceeds to step S134.
[0055]
In step S133, the combination of the manually input shutter speed and aperture value is determined.
[0056]
In step S134, a circle of confusion based on the remaining adjustment amount is calculated based on the determined aperture value and the used focal length of the photographing lens.
[0057]
In step S135, if the circle of confusion calculated in step S134 falls within the reference final allowable circle of confusion (= 10 μm), the flow proceeds to step S138, and if it exceeds the final allowable circle of confusion, the flow proceeds to step S136.
[0058]
In step S136, the range of ΔX before and after the detected final in-focus position is searched by the second focus adjustment unit 4, an evaluation value of the contrast AF is obtained, and the second focus adjustment unit 4 is stopped at the optimum position. . Here, the search range is ΔX = Xd + Xaf, and the search range is set to the minimum area that covers the detection error of the phase difference AF and allows the peak to be confirmed during the contrast AF. The contents of step S136 are shown in the flowchart of FIG. In step S137, the fine adjustment completion flag is turned on, and then the process proceeds to step S139.
[0059]
In step S138, the fine adjustment completion flag is turned off.
[0060]
In step S139, an in-focus display is displayed in the EVF. In step S140, the current position of the focus lens 3 is stored.
[0061]
In step S141, if Sw1 of the first stage of the release switch is off, it is determined that interruption of the shooting preparation has been instructed, and the process returns to step S104.
[0062]
In step S142, if Sw2 of the second stage of the release switch is on, it is determined that a shooting instruction has been issued, and the process proceeds to step S152.
[0063]
In step S143, if the main electronic dial 20 or the sub electronic dial 21 is rotating, the flow proceeds to step S144 assuming that an exposure control instruction has been entered, and if not, the flow returns to step S141.
[0064]
In step S144, exposure control is performed based on the content specified in step S143 according to the set exposure mode. Exposure control is performed based on the relationship shown in FIG.
[0065]
In step S145, the updated result of the exposure control is displayed in the EVF.
[0066]
In step S146, if the fine adjustment completion flag is on, the process returns to step S141, and if it is off, the process proceeds to step S147.
[0067]
In step S147, a circle of confusion based on the remaining adjustment amount is calculated based on the determined aperture value and the used focal length of the photographing lens.
[0068]
In step S148, if the circle of confusion calculated in step S147 is within the reference final allowable circle of confusion (= 10 μm), the flow proceeds to step S141, and if it exceeds the final allowable circle of confusion, the flow proceeds to step S149.
[0069]
In step S149, the range of ΔX before and after the detected final in-focus position is searched by the second focus adjustment unit 4, the evaluation value of the contrast AF is obtained, and the second focus adjustment unit 4 is stopped at the optimum position. . Here, the search range is ΔX = Xd + Xaf, and the search range is set to the minimum area that covers the detection error of the phase difference AF and allows the peak to be confirmed during the contrast AF. The contents of step S149 are shown in the flowchart of FIG.
[0070]
In step S150, the fine adjustment flag is turned on. In step S151, the current position of the focus lens 3 is stored, and the process returns to step S141.
[0071]
In step S152, a shooting sequence is performed. In step S153, the captured image is recorded in the nonvolatile memory.
[0072]
When the recording is completed, the photographing operation is completed, and the process returns to step S104. Thus, the shooting sequence is performed.
[0073]
FIG. 6 is a flowchart showing the operation when the exposure mode setting means 19 rotates.
[0074]
If the exposure mode setting means 19 has entered the program mode in step S161, the flow advances to step SS170.
[0075]
If the exposure mode setting means 19 has entered the shutter speed priority mode in step S162, the flow advances to step S168.
[0076]
If the exposure mode setting means 19 has entered the aperture priority mode in step S163, the flow advances to step S166.
[0077]
In step S164, the exposure mode is set to manual. In step S165, the shutter speed and the aperture value are set to default values. After the setting, the process returns to step S104.
[0078]
In step S166, the exposure mode is set to the aperture priority mode. In step S167, the aperture value is set to a default value. After the setting, the process returns to step S104.
[0079]
In step S168, the exposure mode is set to the shutter speed priority mode. In step S169, the shutter speed is set to a default value. After the setting, the process returns to step S104.
[0080]
In step S170, the exposure mode is set to the program mode. After the setting, the process returns to step S104.
[0081]
The above is the operation corresponding to the rotation of the exposure mode setting means 19.
[0082]
FIG. 7 is a flowchart showing an operation corresponding to the rotation of the main electronic dial 20.
[0083]
If the exposure mode is the program mode in step S171, the function of the main electronic dial 20 is a program shift, and is invalid at the time when the shutter speed and the aperture value have not been determined, so that the process returns to step S104.
[0084]
In step S172, if the exposure mode is aperture priority, the process proceeds to step S174.
[0085]
In step S173, since the exposure mode is manual or shutter speed priority, the shutter speed is changed according to the rotation direction of the main electronic dial. After the change, the process returns to step S104.
[0086]
In step S174, since the exposure mode is aperture priority, the aperture value is changed according to the rotation direction of the main electronic dial. After the change, the process returns to step S104.
[0087]
The above is the operation corresponding to the rotation of the main electronic dial 20.
[0088]
FIG. 8 is a flowchart showing an operation corresponding to the rotation of the sub electronic dial 21.
[0089]
In step S175, if the exposure mode is manual, the process proceeds to step S177; otherwise, the process proceeds to step S176.
[0090]
In step S176, the exposure correction amount is changed according to the rotating direction of sub electronic dial 21. After the change, the process returns to step S104.
[0091]
In step S177, the aperture value is changed according to the rotating direction of the sub electronic dial. After the change, the process returns to step S104.
[0092]
The above is the operation corresponding to the rotation of the sub electronic dial 21.
[0093]
FIG. 9 is a flowchart showing the TVAF operation in steps S136 and S149.
[0094]
In step S201, a search range of the contrast AF is set. The search range is set at a position indicated by the phase difference AF as a center position and ΔX before and after the center position. The contents of ΔX are the same as those described above.
[0095]
In step S202, the focus lens 3 is moved from the current position to the side closer to the end of the search range by controlling the second focus adjustment unit 4.
[0096]
In step S203, the evaluation value of the contrast AF is fetched.
[0097]
In step S204, the evaluation value acquired in step S203 and the position of the focus lens 3 are stored as an evaluation value history.
[0098]
In step S205, it is determined whether the lens has passed the focal point with reference to the evaluation value history. If it has passed, the process proceeds to step S208. If it has not passed, the process proceeds to step S206.
[0099]
In step S206, if all the search ranges set in step S201 have been searched, the process proceeds to step S210. If the search area remains, the process proceeds to step S207.
[0100]
In step S207, the second focus adjusting means 4 is controlled to update the position of the focus lens 3. After updating, the process proceeds to step S203. In the processing of steps S203 to S207, a peak search of the contrast AF is performed.
[0101]
In step S208, the second focus adjustment unit 4 is moved to a position indicating the peak position from the evaluation value history. In step S209, the peak evaluation value as the result of the contrast AF is stored, and the process ends. Return to the main routine.
[0102]
In step S210, the focus lens 3 is moved to the center position of the search range by the second focus adjustment unit 4. This is equivalent to moving to the position of the center value as a result of the phase difference AF. In step S211, the fact that contrast AF has been disabled is stored, and the process ends. Return to the main routine.
[0103]
Thus, the photographing sequence is executed. If the second and subsequent frames are photographed while the power is on, the initialization of the second focus adjustment unit 4 has not been performed first, so the determination in step S123 based on the position stored in step S140 or step S149. Is performed.
[0104]
As shown in the above sequence, the second focus adjusting means 4 is used for fine adjustment operation for final focusing, and the first focus adjusting means 6 is for coarse adjustment to near the in-focus position.
[0105]
In this configuration, in order to achieve the above function, the two focus adjusting units have different characteristics. In other words, the second focus adjusting means 4 performs the one-sided shift to eliminate the influence of the backlash and finely sets the focus adjusting pitch. On the other hand, the first focus adjusting means 6 is set with high speed operation as the highest priority, and the play is increased in order to reduce the driving load. The focus adjustment pitch is also coarse. For this reason, the amount of backlash at the time of reversal is large, and fine adjustment cannot be performed.
[0106]
As described above, a circle of confusion is obtained from the focal length and aperture value of the lens at the time of shooting, and when it is determined that there is no need for comparison with the allowable circle of confusion, the fine adjustment operation for final focusing is not performed. Higher focal speeds have been achieved.
[0107]
Also, even if the focus has been completed only by coarse adjustment once, if the shooting aperture value changes until the final shooting, the necessity of fine adjustment is determined again, and if fine adjustment is required, fine adjustment is performed, so it is necessary Focusing accuracy can be maintained.
[0108]
Further, since the interchangeable lens has built-in means for adjusting both the coarse adjustment and the fine adjustment, it is easy to optimize the range of the coarse adjustment and the fine adjustment, and to avoid complication of the total system. Becomes possible.
[0109]
In the present embodiment, automatic setting is performed depending on the aperture value of the final photographing for the presence / absence of fine adjustment, that is, the first state of only coarse adjustment according to the present invention and the second state of combining coarse and fine adjustment. However, it is also possible to provide switching means for switching the presence or absence of fine adjustment according to the user's intention. The switching means can be easily realized by setting it as one position such as an AF mode changeover switch. If a manual switching means is provided, the camera can be set without misunderstanding what purpose the user is taking, such as shutter timing priority and focus priority, and it is possible to provide an appropriate focus adjustment mode It is.
[0110]
(Second embodiment)
FIG. 10 is a view showing a configuration of an automatic focusing apparatus according to a second embodiment, in which the present invention is applied to a digital still camera of an interchangeable lens type. Mounted on the side.
[0111]
In FIG. 10, reference numeral 51 denotes a digital still camera body, and reference numeral 52 denotes an interchangeable lens. The interchangeable lens 52 includes a focus lens 53, and the focus is adjusted by the focus lens 53.
[0112]
Numeral 54 denotes first focus adjusting means for adjusting the focus lens 53 in the optical axis direction.
[0113]
Reference numeral 55 denotes a lens control circuit, which communicates with the digital still camera body 51 and controls the first focus adjusting means 54.
[0114]
Reference numeral 56 denotes a half mirror, 57 denotes an image sensor, and 58 denotes second focus adjusting means for adjusting the image sensor 57 in the optical axis direction.
[0115]
In the present embodiment, the first focus adjustment means 54 on the interchangeable lens 52 side is for coarse adjustment, and the second focus adjustment means on the digital still camera body 51 is for fine adjustment.
[0116]
59 is a phase difference AF sensor. The half mirror 56 divides the photographic light beam into the image sensor 57 and the phase difference AF sensor 59. With this configuration, the imaging operation and the phase difference AF detection operation can be performed simultaneously.
[0117]
Reference numeral 60 denotes an LCD panel for an electronic viewfinder, which has a built-in backlight. 61 is a finder optical system. With this configuration, the LCD panel 60 is observed through the finder optical system 61.
[0118]
Reference numeral 62 denotes first focus evaluation means, which calculates the amount of defocus from the output of the phase difference AF sensor 59.
[0119]
An image processing unit 63 processes an output signal of the image sensor 57 to extract contrast information of the image, performs white balance, γ processing, color matrix processing, and the like to form a captured image and an image for a finder. The finder image formed by the image processing means 63 is sent to the LCD panel 60, and the finder image displayed on the LCD panel 60 is observed via the finder optical system 61.
[0120]
Reference numeral 64 denotes a second focus evaluation unit which outputs a focus evaluation value by judging the history of contrast information obtained from the image processing unit 63.
[0121]
A camera control circuit 65 controls the entire digital still camera body 51.
[0122]
A lens interface circuit 66 exchanges signals with the lens control circuit 55 of the interchangeable lens 52.
[0123]
67 is a release switch. Reference numeral 68 denotes an exposure mode setting means, which has the same configuration as the exposure mode setting means 19 of the first embodiment.
[0124]
69 is a main electronic dial, and 70 is a sub electronic dial. Both dials 69, 70 are configured to be able to detect the amount of rotation by endless rotation. The main electronic dial 69 and the sub electronic dial 70 are configured similarly to the main electronic dial 20 and the sub electronic dial 21 of the first embodiment.
[0125]
The image photographed by the digital still camera described above is stored in a non-volatile memory (not shown) or the like.
[0126]
Hereinafter, the control accuracy of the first focus adjustment unit 54 and the second focus adjustment unit 58 will be described. The specifications related to the accuracy in the present embodiment are as follows.
Image sensor size: 24mm long, 36mm wide
Pixel pitch: 5 μm
Effective pixels: 3.456 million pixels (4800 * 7200 Pixel)
Pixel configuration: RGB Bayer array
EVF pixel configuration: 300 * 450 * RGB Pixel
EVF mode reading ・ ・ ・ 1/16 thinned out both vertically and horizontally
EVF allowable circle of confusion: 100 μm
Coarse confusion circle diameter 35 μm
Fine adjustment permissible circle of confusion: 10 μm
[0127]
Here, the coarse adjustment permissible circle of confusion is determined under the condition that an image is printed out in a cabinet size and viewed at a clear viewing distance.
[0128]
The EVF allowable circle of confusion diameter and the fine-adjustment circle of confusion are determined to be twice the sampling interval according to the sampling theorem.
[0129]
The diameter of the permissible circle of confusion at the time of fine adjustment corresponds to an application in which a captured image is enlarged to a size equal to or greater than a pixel to confirm the image.
[0130]
In order to achieve the confusion circle diameter, the following relationship is satisfied. The control pitch of the first focus adjustment means 58 is controlled at ＊* F * 35 μm, where F is the open Fno. It is. The detection accuracy of the phase difference AF is also set to ＊* F * 35 μm or less. The control pitch of the second focus adjusting means 54 is ＊* F * 10 μm.
[0131]
The operation of the digital still camera according to the second embodiment configured as described above can be performed in the same manner as in the first embodiment.
[0132]
According to this configuration, the first focus adjustment unit 58 for coarse adjustment is mounted on the interchangeable lens 52 side, and the second focus adjustment unit 54 for fine adjustment is mounted on the digital still camera body 51 side. A reduction in system cost when multiple lenses are included is achieved.
[0133]
(Other embodiments)
A software program for realizing the functions of the above-described embodiment is provided to an apparatus connected to the various devices or a computer in a system so as to operate various devices to realize the functions of the above-described embodiments. The present invention also includes a case in which the present invention is implemented by supplying a code and operating the various devices according to a program stored in a computer (CPU or MPU) of the system or the apparatus.
[0134]
In this case, the software program code itself implements the functions of the above-described embodiment, and the program code itself constitutes the present invention. As a transmission medium for the program code, a communication medium (a wired line or a wireless line such as an optical fiber) in a computer network (LAN, a WAN such as the Internet, a wireless communication network, etc.) system for transmitting and supplying the program information as a carrier wave. Etc.) can be used.
[0135]
Further, means for supplying the program code to a computer, for example, a recording medium storing the program code constitutes the present invention. As a recording medium for storing such a program code, for example, a flexible disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a magnetic tape, a nonvolatile memory card, a ROM, and the like can be used.
[0136]
When the computer executes the supplied program code, not only the functions of the above-described embodiments are realized, but also the OS (Operating System) or other application software running on the computer. Needless to say, such a program code is also included in the embodiment of the present invention when the functions of the above-described embodiment are realized in cooperation with the above.
[0137]
Further, after the supplied program code is stored in a memory provided in a function expansion board of a computer or a function expansion unit connected to the computer, a CPU provided in the function expansion board or the function expansion unit based on the instruction of the program code. It is needless to say that the present invention also includes a case where the functions of the above-described embodiments are implemented by performing part or all of the actual processing.
[0138]
It should be noted that the shapes and structures of the respective parts shown in the above-described embodiments are merely examples of the specific embodiments for carrying out the present invention, and the technical scope of the present invention is limited thereby. It must not be interpreted. That is, the present invention can be embodied in various forms without departing from the spirit or main features thereof.
[0139]
Hereinafter, examples of embodiments of the present invention will be listed.
(Embodiment 1) Evaluation value obtaining means for obtaining an evaluation value of phase difference autofocus;
Evaluation value obtaining means for obtaining an evaluation value of contrast detection autofocus;
Focus adjustment means for coarse adjustment;
Focus adjustment means for fine adjustment;
Selection means for selecting a first state in which focus adjustment is performed only by the focus adjustment means for coarse adjustment and a second state in which the focus adjustment means for coarse adjustment and the focus adjustment means for fine adjustment are combined. An automatic focusing device, comprising:
[0140]
(Embodiment 2) The selection means is an allowable focus range determination means for determining an allowable focus range at the time of photographing, and a determination means for determining whether the determined allowable focus range can be dealt with by coarse adjustment. The automatic focusing apparatus according to the first embodiment, wherein the first state is selected when coarse adjustment is possible.
[0141]
In the second embodiment as described above, the aperture value at the time of shooting, the circle of confusion determined from the lens focal length and the defocus amount and the permissible circle of confusion are compared, and if fine adjustment is unnecessary, only coarse adjustment is performed. It is possible to automatically optimize the adjustment speed.
[0142]
(Embodiment 3) The automatic focusing apparatus according to embodiment 2, wherein, when the assumed circle of confusion has changed, if necessary, the selection means starts autofocus again and selects the second state. Adjustment device.
[0143]
In the third embodiment described above, when the assumed circle of confusion changes, such as when the aperture value is changed after the shutter is half-pressed, it is possible to perform the fine adjustment again as needed to guarantee the focusing accuracy.
[0144]
(Embodiment 4) The automatic focus adjustment apparatus according to Embodiment 2 or 3, wherein the coarse adjustment is performed by the coarse adjustment focus adjustment means, and the target adjustment position at the time of the coarse adjustment is obtained by phase difference autofocus.
[0145]
In the fourth embodiment, the focus speed can be increased by limiting the focus adjustment unit and the focus detection unit used in the first coarse adjustment.
[0146]
(Embodiment 5) The fine adjustment according to any one of the second to fourth embodiments, wherein the fine adjustment is performed by the focus adjustment means for fine adjustment, and the fine adjustment is performed based on the evaluation value of the contrast detection autofocus. Automatic focusing device.
[0147]
In the fifth embodiment described above, it is possible to increase the precision of the fine adjustment.
[0148]
(Embodiment 6) The automatic focus adjustment device according to any one of Embodiments 2 to 5, wherein the coarse adjustment device has an adjustment accuracy with which a viewfinder observation image is determined to be in focus.
[0149]
In the sixth embodiment described above, even if the adjustment is stopped by the coarse adjustment, the in-focus state appears in the viewfinder, so that a sense of security for the user can be obtained.
[0150]
(Embodiment 7) An imaging apparatus comprising: an imaging apparatus main body; and an interchangeable lens, and including the automatic focusing apparatus according to any one of Embodiments 1 to 6.
[0151]
(Embodiment 8) The imaging apparatus according to Embodiment 7, wherein the focus adjustment unit for coarse adjustment and the focus adjustment unit for fine adjustment are mounted on the interchangeable lens.
[0152]
(Embodiment 9) The imaging apparatus according to embodiment 7, wherein the interchangeable lens is provided with the focus adjustment means for coarse adjustment, and the focus adjustment means for fine adjustment is mounted on the imaging apparatus body.
[0153]
(Embodiment 10) A focus adjustment method for adjusting focus using a focus adjustment unit for coarse adjustment and a focus adjustment unit for fine adjustment,
A procedure for obtaining an evaluation value of the phase difference autofocus;
A procedure for obtaining an evaluation value of contrast detection autofocus;
There is a procedure for selecting a first state in which focus adjustment is performed only by the coarse adjustment focus adjustment means and a second state in which the coarse adjustment focus adjustment means and the fine adjustment focus adjustment means are combined. A focusing method.
[0154]
(Embodiment 11) A program for controlling an automatic focus adjustment device including a focus adjustment unit for coarse adjustment and a focus adjustment unit for fine adjustment,
A process of obtaining an evaluation value of the phase difference autofocus;
Processing for obtaining an evaluation value of contrast detection autofocus;
A process of selecting a first state in which focus adjustment is performed only by the coarse adjustment focus adjustment unit and a second state in which the coarse adjustment focus adjustment unit and the fine adjustment focus adjustment unit are combined is executed. A program characterized by causing
[0155]
(Embodiment 12) A computer-readable storage medium storing the program according to Embodiment 11.
[0156]
【The invention's effect】
As described above, according to the present invention, the first state in which focus adjustment is performed only by the coarse adjustment focus adjustment unit and the second state in which the coarse adjustment focus adjustment unit and the fine adjustment focus adjustment unit are combined are described. Since state 2 is selected, fine adjustment can be performed only when necessary, and the focus adjustment speed can be increased.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration of an automatic focusing apparatus according to a first embodiment.
FIG. 2 is a diagram for explaining an exposure mode setting means 10;
FIG. 3 is a diagram for explaining functions of a main electronic dial 20 and a sub electronic dial 21;
FIG. 4 is a flowchart illustrating a processing operation of the digital still camera according to the present embodiment.
FIG. 5 is a flowchart showing a processing operation of the digital still camera.
FIG. 6 is a flowchart illustrating a processing operation of the digital still camera.
FIG. 7 is a flowchart showing a processing operation of the digital still camera.
FIG. 8 is a flowchart showing a processing operation of the digital still camera.
FIG. 9 is a flowchart illustrating a processing operation of the digital still camera.
FIG. 10 is a diagram illustrating a configuration of an automatic focusing apparatus according to a second embodiment.
[Explanation of symbols]
1 Digital still camera body
2 interchangeable lenses
3 Focus lens
4 Second focus adjusting means
5 Focus lens barrel
6. First focus adjusting means
7 Lens control circuit
8 Half mirror
9 Image sensor
10 Phase difference AF sensor
11 LCD panel
12 Viewfinder optical system
13 First focus evaluation means
14 Image processing means
15 Second focus evaluation means
16 Camera control circuit
17 Lens interface circuit
18 Release switch
19 Exposure mode setting means
20 Main e-dial
21 Quick Control Dial

Claims (1)

Evaluation value obtaining means for obtaining an evaluation value of the phase difference autofocus;
Evaluation value obtaining means for obtaining an evaluation value of contrast detection autofocus;
Focus adjustment means for coarse adjustment;
Focus adjustment means for fine adjustment;
Selection means for selecting a first state in which focus adjustment is performed only by the focus adjustment means for coarse adjustment and a second state in which the focus adjustment means for coarse adjustment and the focus adjustment means for fine adjustment are combined. An automatic focusing device, comprising:

Images