Control device, lens device, image capturing device, control method, and program

Abstract

To provide a control device that enables highly accurate correction of first information.SOLUTION: A control device (110) for controlling an optical system comprising a zoom lens group (102) configured to move when zooming and a focusing lens group (105) configured to move when focusing is provided, the control device comprising acquisition means (110a) for acquiring first information indicative of a relationship between a position of the zoom lens group and a corresponding position of the focusing lens group when focused, and control means (110b) for controlling the focusing lens group using the first information. The first information includes a design value indicative of a relationship between the zoom lens group and the focusing lens group of the optical system, and a correction value that varies depending on an object distance. The control means uses the correction value to correct the design value indicative of the relationship between the zoom lens group and the focusing lens group corresponding to the same object distance.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a control device, a lens device, an imaging device, a control method, and a program. [Background technology]

[0002] Conventionally, lens devices have been known that control the focus lens group using trajectory information (electronic cam data) that indicates the relationship between the position of the zoom lens group and the position of the focus lens group that is in focus at the position of the zoom lens group. Furthermore, because lens devices vary from one another, it is necessary to correct deviations from the design values.

[0003] Patent Document 1 discloses a lens device that corrects trajectory information based on correction data obtained by measuring the actual positions of the focus lens group when focusing at multiple zoom positions by performing reciprocating zooming operations between the wide-angle side and the telephoto side on an object at infinity. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-242356 Summary of the Invention [Problem to be solved by the invention]

[0005] The lens device disclosed in Patent Document 1 cannot accurately correct trajectory information relating to any subject distance other than infinity.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a control device that is capable of correcting trajectory information with high accuracy. [Means for solving the problem]

[0007] A control device according to one aspect of the present invention is a control device for controlling an optical system including a zoom lens group that moves during zooming and a focus lens group that moves during focusing, and includes: an acquisition means for acquiring first information indicating the relationship between the position of the zoom lens group and a position of the focus lens group corresponding to the position of the zoom lens group when focusing; and a control means for controlling the focus lens group using the first information, wherein the first information includes a design value indicating the relationship between the zoom lens group and the focus lens group of the optical system, and a correction value that differs depending on the subject distance, and the control means uses the correction value to correct the design value indicating the relationship between the zoom lens group and the focus lens group that correspond to the same subject distance.

[0008] Other objects and features of the present invention will be described in the following embodiments. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a control device that can correct trajectory information with high accuracy. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 2 is a block diagram of an imaging system according to each embodiment. [Figure 2] FIG. 10 is an explanatory diagram of a correction method as a comparative example. [Figure 3] FIG. 4 is an explanatory diagram of a correction method in the first embodiment. [Figure 4] FIG. 10 is an explanatory diagram of the error characteristics of the lens in the second embodiment. [Figure 5] FIG. 10 is an explanatory diagram of a correction method in the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0012] (First embodiment) First, an imaging system 100 according to a first embodiment of the present invention will be described with reference to Fig. 1. Fig. 1 is a block diagram of the imaging system 100. The imaging system 100 is an interchangeable lens camera system including a camera body (imaging device) 128 and an interchangeable lens (lens device) 111 that can be attached to and detached from the camera body 128. However, this embodiment is not limited to this, and can also be applied to an imaging device in which the camera body and lens device are integrally configured.

[0013] The interchangeable lens 111 has an optical system (image pickup optical system) that forms an image (optical image) of a subject. The image pickup optical system includes, along an optical axis OA, a first lens 101, a zoom lens (zoom lens group) 102, an aperture stop (aperture stop) 103, a fixed third lens 104, and a focus lens (focus lens group) 105. In this embodiment, the zoom lens 102 is a lens group (zoom lens group) that moves during zooming, and the focus lens 105 is a lens group (focus lens group) that moves during focusing. Each lens group may be a single lens or multiple lenses.

[0014] The lens microcomputer 110 of the interchangeable lens 111 is a control device that controls the imaging optical system. The lens microcomputer 110 has an acquisition unit 110a and a control unit 110b. The acquisition unit 110a acquires trajectory information (cam trajectory, first information) that indicates the relationship between the position of the zoom lens 102 and the position of the focus lens 105 that is focused at the position of the zoom lens 102. In other words, the trajectory information is information that indicates the relationship between the position of the zoom lens 102 and the position of the focus lens 105 that corresponds to the position of the zoom lens 102 when focused. The control unit 110b controls the focus lens 105 using the trajectory information acquired by the acquisition unit 110a. The trajectory information includes design values ​​(design data) that indicate the relationship between the zoom lens 102 and the focus lens 105 of the imaging optical system, and correction values ​​(correction data, adjustment values) that vary depending on the subject distance. The control unit 110b uses the correction values ​​to correct the design values ​​that indicate the relationship between the zoom lens 102 and the focus lens 105 that correspond to the same subject distance.

[0015] The image sensor 122 of the camera body 128 is a photoelectric conversion element such as a CMOS (Complementary Metal-Oxide-Semiconductor) sensor or a CCD (Charge Coupled Device) sensor. The image sensor 122 photoelectrically converts an optical image formed by an imaging optical system and outputs an analog electrical signal. The signal processing unit 123 performs signal processing such as signal amplification on the analog electrical signal converted by the image sensor 122 and outputs a digital signal. The signal processing unit 123 also performs imaging processing such as color correction and white balance on the digital signal and outputs image data. The recording processing unit 124 records the image data output from the signal processing unit 123. The image data can be displayed on the electronic viewfinder 121.

[0016] The digital signal generated by the signal processing unit 123 is also output to a contrast signal generation unit 126. The contrast signal generation unit 126 generates a contrast signal by using one or more high-frequency signal integral values ​​obtained by integrating the amount of high-frequency components extracted from multiple specific regions of the luminance signal using a high-pass filter. The contrast signal is output to a camera microcomputer 127 and is used to determine the focus state (in-focus state).

[0017] In recent years, a sensor-integrated phase difference detection method provided with an element for measuring a phase difference has become known as an example of the image sensor 122. The defocus detection unit 125 detects (calculates) the amount of defocus using the phase difference signal obtained by the image sensor 122. The defocus amount is output to the camera microcomputer 127.

[0018] The camera microcomputer 127 in the camera body 128 and the lens microcomputer 110 in the interchangeable lens 111 communicate with each other at a predetermined interval or as needed. The camera microcomputer 127 outputs lens control data (focus drive commands (drive pulses), optical information acquisition commands, aperture commands, etc.) to the lens microcomputer 110. The lens microcomputer 110 outputs information used for automatic exposure, automatic light control, automatic focus adjustment, etc. to the camera microcomputer 127. This information includes optical information such as the lens position, sensitivity, focal length, shooting distance, subject distance, image distance, best focus correction value, maximum aperture F-number, minimum F-number, exit pupil value, image height exit pupil value, correction value, and lens extension amount per pulse.

[0019] The lens microcomputer 110 drives each part of the imaging optical system using lens control data received from the camera microcomputer 127. The aperture driver 107 changes the aperture amount (aperture diameter) of the aperture 103 based on commands from the lens microcomputer 110. The aperture driver 107 controls the aperture 103 using a stepping motor or voice coil motor (VCM), a hall sensor that senses the current flowing in the coil or a sensor that detects the end position, and detection means that detects the aperture position.

[0020] Focus lens detection unit 108 detects the position (focus position) of focus lens 105. The focus position detected by focus lens detection unit 108 is output to lens microcomputer 110. Focus lens driving unit 109 drives focus lens 105 in a direction along optical axis OA (optical axis direction) based on a command from lens microcomputer 110.

[0021] The position (zoom position, focal length) of the zoom lens 102 is changed by mechanical interlocking via a zoom operation ring (not shown). A zoom lens position detection unit 106 detects the position of the zoom lens 102.

[0022] In this configuration, when a user operates the zoom ring to change the zoom position (focal length), the zoom lens 102 changes the focal length mechanically in conjunction with the zoom ring. At this time, if you try to focus at the same subject distance due to the change in zoom position, the focus position will change. Therefore, to maintain focus while zooming, you can move the focus position in accordance with the zoom position, thereby maintaining the focus at a specific subject distance.

[0023] Electrical focus control using a cam locus (locus information) to control continuous changes according to the zoom position and focus position is called electronic cam control, in contrast to conventional control using a mechanical cam. Representative points (data) of the correspondence between the focus position and the zoom position for each subject distance are stored in the storage unit 112 as design values ​​of the cam locus according to the zoom position and focus position. The storage unit 112 is, for example, a read-only memory (ROM) or an electrically erasable programmable read-only memory (EEPROM). The storage unit 112 also references the data stored in the storage unit 112 and stores correction amounts (correction values, adjustment values) corresponding to deviations from the design values ​​of each interchangeable lens 111. The lens microcomputer 110 adds the design values ​​and the correction amounts together to move the focus lens 105 so that the focus is appropriate for zoom fluctuations.

[0024] In this embodiment, the storage unit 112 may be an internal memory built into the lens microcomputer 110. In this embodiment, at least a portion of the data stored in the storage unit 112 may be stored in a storage unit of a device separate from the interchangeable lens 111, such as a cloud computing system. In this case, the lens microcomputer 110 or the camera microcomputer 127 can obtain the necessary data via wireless communication or the like.

[0025] Furthermore, for intermediate zoom positions or focus positions other than the representative points, the distance (deviation ratio) from the two representative points is calculated, and linear interpolation is performed according to that ratio to calculate a highly accurate position. Even if the focus lens 105 has multiple focus groups, similar processing can be performed by having data on the same subject distance for the multiple focus groups with respect to zoom fluctuations.

[0026] Next, a comparative example of a method for correcting misalignment of individual lenses will be described with reference to Figures 2(A) and (B). Figure 2(A) shows electronic cam data of design values ​​and individual difference data at infinity. Figure 2(B) shows electronic cam data when individual difference data is taken into account in the electronic cam data of design values. In Figures 2(A) and (B), the horizontal axis represents zoom position and the vertical axis represents focus position. The lines, starting from the top, indicate the design values ​​for the focus position required to maintain focus at each zoom position at the same subject distance: infinity, 1 m, and 0.1 m. For example, to maintain focus at infinity during zooming, the focus position must be controlled to move along the top line representing the same subject distance at infinity. Note that values ​​not listed for the same subject distance can be freely determined by calculating the cam spacing ratio.

[0027] Then, the individual lens misalignment amounts are measured by measuring the focus position at which each zoom position focuses on an object at infinity. In Figure 2(A), the measurement points (3 points) for each zoom are indicated by black circles. As shown in Figure 2(B), the individual focus misalignment values ​​for an object at infinity are offset from the design values ​​for all object distances by adding the measurement data at infinity to the design values. This improves zoom focus misalignment for each interchangeable lens 111 at object distances other than infinity compared to no correction. However, at the closest distance of 0.1 m from infinity, which is the furthest point from infinity, focus misalignment occurs compared to infinity.

[0028] Next, a method for correcting misalignment of individual lenses in this embodiment will be described with reference to Figures 3(A) and 3(B). Figure 3(A) is a diagram showing electronic cam data of design values ​​and infinite individual difference data. Figure 3(B) is a diagram showing electronic cam data when individual difference data is taken into account in electronic cam data of design values. The horizontal axis represents zoom position (focal length), and the vertical axis represents focus position.

[0029] The straight lines, from top to bottom, indicate the design values ​​for the focus position to maintain focus at each zoom position at the same subject distance: infinity (first subject distance), 1 m (third subject distance), and 0.1 m (second subject distance). The individual lens deviations are measured by measuring the focus position at each zoom position for a subject at infinity. The measurement points (first correction values) for each zoom position are indicated by white circles. The individual deviations are also measured by measuring the focus position at each zoom position for a subject at a subject distance of 0.1 m. The measurement points (second correction values) for each zoom position are indicated by black circles.

[0030] As shown in Figure 3(B), the focus error value for an individual lens with an infinitely far subject is calculated by adding the amount of deviation measured at infinity to the design value. The electronic cam data for a close subject at 0.1 m is calculated by adding the amount of deviation measured with a close subject at 0.1 m to the design value. The electronic cam data for an intermediate subject at a subject distance of 1 m is calculated by adding the data for an infinitely far subject and a close subject at a subject distance of 0.1 m at a predetermined ratio to obtain the deviation amount (third correction value), and then adding this to the design value. Here, the predetermined ratio is a ratio corresponding to the reciprocal of the subject distance. For example, adding the reciprocal of the subject distance can result in an optically accurate correction value. In this case, the subject distance for an infinitely far subject may be any finite value, such as 10,000. Using this method, intermediate values ​​for which no data is available can be calculated by interpolation.

[0031] As described above, in this embodiment, the control device (lens microcomputer 110) acquires trajectory information (electronic cam data including design values ​​and correction values) from the storage unit and corrects design values ​​(design data) for the same subject distance using correction values ​​(correction data, adjustment values). Preferably, the correction values ​​include a first correction value (FIG. 3) obtained by measurement for a first subject distance (e.g., infinity), a second correction value obtained by measurement for a second subject distance, and a third correction value for a third subject distance. The third correction value is a correction value obtained using the first correction value and the second correction value.

[0032] For example, the storage means stores design electronic cam data (design values) for a first object distance (e.g., infinity object distance) at multiple (e.g., three) focal lengths of the interchangeable lens 111, and correction values ​​(first correction values) that are difference information from the design values. The storage means also stores design electronic cam data (design values) for a second object distance (e.g., closest object distance) that is different from the first object distance at multiple focal lengths, and correction values ​​(second correction values) that are difference information from the design values. Then, the control means 110b calculates the correction values ​​for a specific focal length and a specific object distance (third object distance) using the first correction value for the first object distance, the second correction value for the second object distance, and data related to a specific object distance.

[0033] Preferably, the third correction value is a correction value obtained by interpolation using the first correction value and the second correction value for each focal length, and more preferably, the third correction value is a correction value obtained by adding the first correction value and the second correction value at a ratio according to the reciprocal of the subject distance.

[0034] According to this embodiment, the locus information (design electronic cam data) for the same object distance is corrected using different correction values ​​depending on the object distance, so that the locus information can be corrected with high accuracy.

[0035] (Second embodiment) Next, a second embodiment of the present invention will be described. First, the error characteristics of a solid lens will be described with reference to FIG. 4. FIG. 4 is an explanatory diagram of the error characteristics of an interchangeable lens 111. In FIG. 4, the horizontal axis represents zoom position (focal length) and the vertical axis represents adjustment value (correction value). The adjustment values ​​at each zoom position at infinity are used as a reference, and adjustment values ​​at subject distances of 0.1 m and 1 m are plotted. This characteristic is proportional to the square of the focal length (zoom position) and to the reciprocal of the subject distance. This embodiment utilizes this characteristic. In other words, if the amount of deviation for a subject other than infinity at a specific zoom position on the close side is known, the overall amount of deviation can be calculated by using data on the amount of deviation for each zoom position for a subject at infinity and data on the amount of deviation for a single zoom position at any subject distance other than infinity.

[0036] Next, a method for correcting misalignment of individual lenses in this embodiment will be described with reference to Figures 5(A) and 5(B). Figure 5(A) is a diagram showing electronic cam data of design values ​​and infinite individual difference data. Figure 5(B) is a diagram showing electronic cam data when individual difference data is taken into account in electronic cam data of design values. The horizontal axis represents zoom position, and the vertical axis represents focus position.

[0037] The straight lines, from top to bottom, indicate the design values ​​for the focus position to maintain focus at each zoom position at the same subject distance: infinity, 1m, and 0.1m. The individual lens deviations are measured by measuring the focus position at each zoom position to focus on a subject at infinity. The measurement points for each zoom are indicated by black circles.

[0038] Furthermore, by measuring the focus position at the telephoto end (TELE end) zoom position for a close subject at a subject distance of 0.1 m, the individual deviation amount (second correction value) for the close subject at 0.1 m is measured. The deviation amount is indicated by the black arrow. As explained with reference to FIG. 4, the relationship between the adjustment value for an infinite subject and other subjects is proportional to the square of the focal length and the reciprocal of the subject distance. Using this relationship, the deviation correction amount for each zoom position for a close subject at 0.1 m is as shown by the curve in FIG. 5(A).

[0039] Using the focus error value for an object at infinity and the focus error value for an object at a close distance of 0.1 m, as shown in Figure 3(B), the electronic cam data for an object at infinity is calculated by adding the amount of error measured at infinity to the design value. Similarly, the electronic cam data for an object at a close distance of 0.1 m is calculated by adding the amount of error measured with the object at a close distance of 0.1 m and the value for each zoom position obtained using the relationship described above to the design value. Similarly, the electronic cam data for an intermediate object at a subject distance of 1 m is calculated by using the relationship that is proportional to the square of the focal length and proportional to the reciprocal of the subject distance, and an adjustment value is obtained by adding this to the design value to obtain the electronic cam data.

[0040] If the deviation correction value for each zoom position and subject distance is ΔX, it can be expressed by the following formula.

[0041] When the deviation amount (correction value, adjustment value) of each zoom and focal length related to the focal length f and the subject distance d is ΔX(f, d), it can be expressed by the following formula.

[0042] ΔX(f, d)=ΔX(f, infinity)+{ΔX(f, nearest)−ΔX(f, infinity)}×f^2 / FT^2×(1 / d) / (1 / DT) FT and DT represent the subject distance and focal length at the point where the deviation amount other than infinity was measured, and represent the intrinsic focal length and intrinsic subject distance. For example, when the deviation amount from the design value at the closest distance of 0.1 m and the Tele end is measured, it is expressed by the following formula.

[0043] ΔX (f, close) = ΔX (Tele end, close 0.1m) x f^2 / focal length at Tele end x (1 / 0.1) / (1 / 0.1) ΔX (f, infinity) is the deviation amount at infinity at all zoom positions, which is the deviation amount of the individual obtained by interpolation calculation. ΔX (Tele end, closest 0.1m) is the deviation amount of the individual measured.

[0044] The above formula allows the relationship to be calculated even if there is only one point of deviation for subject distances other than infinity. This allows for data reduction, and since values ​​other than the above variable parameters can be calculated once and reused, the calculation load can be reduced.

[0045] In this embodiment, the second correction value is a correction value for at least one focal length. The third correction value is a correction value obtained using the first correction value, the second correction value, and error characteristic data of the optical system that varies depending on the object distance. The error characteristic data is proportional to the square of the focal length and proportional to the reciprocal of the object distance. According to this embodiment, it is only necessary to acquire a correction value for at least one focal length as the second correction value, and therefore processing can be performed efficiently in a short time.

[0046] (Other embodiments) The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. It can also be realized by a circuit (e.g., ASIC) that realizes one or more functions.

[0047] According to each embodiment, blurring during zooming can be reduced not only for infinitely far objects but also for close objects, and blurring can be efficiently reduced for any object distance and zoom position for which no data is available. Therefore, according to each embodiment, it is possible to provide a control device, a lens device, an imaging device, a control method, and a program that can correct trajectory information with high accuracy.

[0048] The disclosure of each embodiment includes the following configurations and methods. (Configuration 1) A control device for controlling an optical system including a zoom lens group that moves during zooming and a focus lens group that moves during focusing, an acquisition means for acquiring first information indicating a relationship between a position of the zoom lens group and a position of the focus lens group corresponding to the position of the zoom lens group when in focus; a control unit that controls the focus lens group using the first information, the first information includes a design value indicating a relationship between the zoom lens group and the focus lens group of the optical system, and a correction value that varies depending on a subject distance; The control device is characterized in that the control means uses the correction value to correct the design value indicating the relationship between the zoom lens group and the focus lens group corresponding to the same subject distance. (Configuration 2) the correction values ​​include a first correction value obtained by measurement for a first object distance, a second correction value obtained by measurement for a second object distance, and a third correction value obtained by measurement for a third object distance; 2. The control device according to configuration 1, wherein the third correction value is a correction value obtained using the first correction value and the second correction value. (Configuration 3) The control device according to configuration 2, wherein the third correction value is a correction value obtained by interpolation using the first correction value and the second correction value for each focal length. (Configuration 4) The control device according to configuration 3, wherein the third correction value is a correction value obtained by adding the first correction value and the second correction value at a ratio according to the reciprocal of the subject distance. (Configuration 5) the second correction value is a correction value related to at least one focal length, The control device according to configuration 2, wherein the third correction value is a correction value obtained using the first correction value, the second correction value, and error characteristic data of the optical system that differs depending on the subject distance. (Configuration 6) 6. The control device according to configuration 5, wherein the error characteristic data is proportional to the square of the focal length and proportional to the reciprocal of the subject distance. (Configuration 7) 7. A lens device comprising the control device according to any one of configurations 1 to 6 and the optical system. (Configuration 8) 8. The lens device according to configuration 7, further comprising storage means for storing the locus information. (Configuration 9) 7. An imaging device comprising the control device according to any one of configurations 1 to 6 and an imaging element. (Method 1) A control method for controlling an optical system including a zoom lens group that moves during zooming and a focus lens group that moves during focusing, comprising: an acquiring step of acquiring first information indicating a relationship between a position of the zoom lens group and a position of the focus lens group corresponding to the position of the zoom lens group when in focus; a control step of controlling the focus lens group using the first information, the first information includes a design value indicating a relationship between the zoom lens group and the focus lens group of the optical system, and a correction value that varies depending on a subject distance; a control method comprising: correcting, in the control step, the design value indicating the relationship between the zoom lens group and the focus lens group corresponding to the same subject distance, using the correction value; (Configuration 10) A program that causes a computer to execute the control method described in Method 1.

[0049] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist of the present invention. [Explanation of symbols]

[0050] 110 Lens microcomputer (control device) 102 Zoom Lens (Zoom Lens Group) 105 Focus lens (focus lens group)

Claims

1. A control device for controlling an optical system including a zoom lens group that moves during zooming and a focus lens group that moves during focusing, an acquisition unit that acquires first information indicating a relationship between a position of the zoom lens group and a position of the focus lens group corresponding to the position of the zoom lens group when in focus; a control unit that controls the focus lens group using the first information, the first information includes a design value indicating a relationship between the zoom lens group and the focus lens group of the optical system, and a correction value that varies depending on a subject distance; The control device is characterized in that the control means uses the correction value to correct the design value indicating the relationship between the zoom lens group and the focus lens group corresponding to the same subject distance.

2. the correction values ​​include a first correction value obtained by measurement for a first object distance, a second correction value obtained by measurement for a second object distance, and a third correction value obtained by measurement for a third object distance; 2. The control device according to claim 1, wherein the third correction value is a correction value obtained using the first correction value and the second correction value.

3. 3. The control device according to claim 2, wherein the third correction value is a correction value obtained by an interpolation calculation using the first correction value and the second correction value for each focal length.

4. 4. The control device according to claim 3, wherein the third correction value is a correction value obtained by adding the first correction value and the second correction value at a ratio according to the reciprocal of the subject distance.

5. the second correction value is a correction value related to at least one focal length, 3. The control device according to claim 2, wherein the third correction value is a correction value obtained using the first correction value, the second correction value, and error characteristic data of the optical system that differs depending on the subject distance.

6. 6. The control device according to claim 5, wherein the error characteristic data is proportional to the square of the focal length and proportional to the reciprocal of the subject distance.

7. A lens device comprising: the control device according to claim 1; and the optical system.

8. 8. The lens device according to claim 7, further comprising storage means for storing the first information.

9. An imaging device comprising: the control device according to claim 1; and an imaging element.

10. A control method for controlling an optical system including a zoom lens group that moves during zooming and a focus lens group that moves during focusing, comprising: an acquiring step of acquiring first information indicating a relationship between a position of the zoom lens group and a position of the focus lens group corresponding to the position of the zoom lens group when in focus; a control step of controlling the focus lens group using the first information, the first information includes a design value indicating a relationship between the zoom lens group and the focus lens group of the optical system, and a correction value that varies depending on a subject distance; a control method comprising: correcting, in the control step, the design value indicating the relationship between the zoom lens group and the focus lens group corresponding to the same subject distance, using the correction value;

11. A program causing a computer to execute the control method according to claim 10.

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