CONTROL DEVICE, LENS DEVICE, IMAGING DEVICE, CONTROL METHOD, AND PROGRAM

Abstract

To provide a control unit that can control a plurality of focus lens groups to increase focus accuracy during a magnification varying operation.SOLUTION: A control unit controls a first focus driving unit (119) and a second focus driving unit (120) that respectively drive a first focus lens group (113) and a second focus lens group (114) movable in an optical axis direction, and has a driving amount calculation unit (115) that periodically calculates the driving speeds or the driving positions of the first focus driving unit and the second focus driving unit. The driving amount calculation unit makes different the method for calculating the driving speeds or the driving positions between a case of driving the first focus lens group and the second focus lens group when performing focusing and a case of driving the first focus lens group and the second focus lens group when not performing focusing.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a control device for controlling driving of a plurality of focus lens groups, a lens device, an imaging device, a control method, and a program.

Background Art

[0002] In an inner focus type zoom lens, when zooming is performed by moving a variable magnification lens from a state focused on a certain subject distance, the position of the image plane changes and the focus becomes blurred. In order to maintain the focused state during the zooming operation, the focus lens group must be moved with respect to the position of the variable magnification lens (zoom tracking control).

[0003] Further, in order to suppress the occurrence of aberrations during focusing, there is known a lens device that controls a plurality of focus lens groups to move in different ways during focusing and zoom tracking control. Patent Document 1 discloses a lens control method for synchronously controlling a plurality of focus lens groups so as to suppress the occurrence of aberrations.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the lens control method disclosed in Patent Document 1, a plurality of focus lens groups are synchronously controlled not only when focusing but also when not focusing such as during a zooming operation (zoom tracking control) so as to suppress the occurrence of aberrations. As a result, the focusing accuracy during the zooming operation may decrease.

[0006] Accordingly, an object of the present invention is to provide a control device, a lens device, an imaging device, a control method, and a program capable of controlling a plurality of focus lens groups to improve focusing accuracy during zooming operation.

Means for Solving the Problems

[0007] A lens control device according to one aspect of the present invention is No. a control device that controls a first focus lens group and a second focus lens group, respectively, When moving in the optical axis direction with a driving amount calculation unit that periodically calculates the driving speed or driving position of each of the first focus driving unit and the second focus driving unit, and the driving amount calculation unit performs focusing when on the first focus lens group and the second focus lens group move in the case of, the first focus drive unit and the second focus drive unit to perform synchronous control, When zooming on the first focus lens group and the second focus lens group move in the case of, the first focus drive unit and the second focus drive unit to perform asynchronous control, and the synchronous control by is using the information regarding the position and speed of the first focus lens group to control the first focus drive unit, using the position regarding information of the first focus lens group to drive unit the second focus control and the the described asynchronous control by is using the information regarding the position and speed of the first focus lens group to control the first focus drive unit, without using the position regarding information of the first focus lens group using the information regarding the position and speed of the second focus lens group to to control the drive unit the second focus.

[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, a lens device, an imaging device, a control method, and a program that can control a plurality of focus lens groups to improve the focusing accuracy during zooming operation.

Brief Description of Drawings

[0010]

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Best Mode for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each figure, the same members are denoted by the same reference numerals, and redundant descriptions are omitted.

Embodiment

[0012] First, referring to FIG. 1, the imaging device in Embodiment 1 of the present invention will be described. FIG. 1 is a block diagram of an imaging device (camera system) 10 in this embodiment. The imaging device 10 is an interchangeable-lens camera system configured to include a camera body 200 and a lens device (zoom lens) 100 detachable from the camera body 200, and is capable of performing still image shooting and moving image shooting. However, this embodiment is not limited thereto, and is also applicable to an imaging device in which the lens device and the camera body are integrally configured.

[0013] The lens device 100 has an optical system (imaging optical system) 110 capable of forming a subject image on the imaging element 210 of the camera body 200, and a lens control unit (control device) 115 capable of communicating with the camera control unit 216 of the camera body 200. As will be described later, the lens control unit 115 has a drive amount calculation unit that periodically calculates the drive speed or drive position of each of the first focus drive unit 119 and the second focus drive unit 120. The optical system 110 includes a zoom lens 111, a diaphragm 112, a first focus lens group 113, and a second focus lens group 114. The first focus lens group 113 and the second focus lens group 114 are movable in a direction along the optical axis OA (optical axis direction), and the distance between the first focus lens group 113 and the second focus lens group 114 changes during focusing. The lens control unit 115 is a computer having a CPU (Central Processing Unit). The lens control unit 115 is electrically connected to a memory 116, a zoom position detection unit 117, a diaphragm drive unit 118, a first focus drive unit 119, and a second focus drive unit 120.

[0014] The zoom lens 111 is movable in the optical axis direction in response to the operation (zoom operation) of a zoom operation unit (zoom operation ring) 122 connected to a zoom drive mechanism (not shown) by the user. By moving the zoom lens 111, the focal length of the imaging optical system is changed (zoomed).

[0015] The memory 116 is a storage unit for storing information, which is composed of a ROM (Read Only Memory), a RAM (Random Access Memory), etc. The memory 116 stores locus data representing the focusing positions of the first focus lens group 113 and the second focus lens group 114 corresponding to the zoom position for each subject distance.

[0016] The zoom position detection unit 117 detects the zoom position using a zoom position sensor such as a variable resistor, and outputs the zoom position data to the lens control unit 115. The zoom position data detected here may be the position of the zoom lens 111 or the operation position of the zoom operation unit 122.

[0017] The aperture drive unit 118 includes an aperture actuator for driving the aperture 112 such as a stepping motor or a voice coil motor, and an aperture sensor for detecting the drive position of the aperture 112 such as a hall element.

[0018] The first focus drive unit 119 and the second focus drive unit 120 are focus actuators such as a stepping motor, a ultrasonic motor, or a voice coil motor, and can drive each focus lens group independently. Also, the first focus drive unit 119 and the second focus drive unit 120 may be configured to include a focus position sensor that detects the positions of the first focus lens group 113 and the second focus lens group 114 in the optical axis direction, such as a potentiometer or an encoder. The aperture actuator of the aperture drive unit 118 and the focus actuators of the first focus drive unit 119 and the second focus drive unit 120 are controlled by a lens control unit 115 that has received an aperture drive command or a focus drive command from the camera control unit 216.

[0019] The camera body 200 includes an imaging element 210, a signal processing unit 211, a recording processing unit 212, an electronic viewfinder 213, a display unit 214, a defocus detection unit 215, a camera control unit 216, and a memory 217. The imaging element 210 is a CMOS sensor or a CCD sensor, receives light from the optical system 110, generates an electrical signal by photoelectric conversion, and outputs the generated electrical signal to the signal processing unit 211. The imaging element 210 has, in addition to pixels for imaging, pixels for focus detection (not shown). The signal processing unit 211 performs various processes such as amplification, noise removal, and color correction on the input electrical signal, and outputs it to the recording processing unit 212. The recording processing unit 212 records the input image and displays this image on the electronic viewfinder 213 or the display unit 214.

[0020] The defocus detection unit 215 detects the in-focus state of the subject image using the imaging element 210. The defocus detection unit 215 detects the phase difference between a pair of subject image signals obtained from the light incident through a microlens that performs pupil division on the focus detection pixels of the imaging element 210, and obtains a defocus amount corresponding to the phase difference. Then, the defocus amount is output to the camera control unit 216.

[0021] The camera control unit 216 is a computer having a CPU, and is electrically connected to the recording processing unit 212, the defocus detection unit 215, and the memory 217. The camera control unit 216 reads and executes the program recorded in the memory 217, and communicates information necessary for autofocus control with the lens control unit 115. Further, the camera control unit 216 generates a focus drive command based on the detection result from the defocus detection unit 215 and the focus position information acquired from the lens device 100. Here, the focus position information to be acquired may be information of either the first focus lens group 113 or the second focus lens group 114, or both. Alternatively, the focus position information may be information of the subject distance or the image plane position calculated based on the position information of the first focus lens group 113 and the second focus lens group 114. In the present embodiment, an example of performing autofocus control of the phase difference detection method using the pixels for phase difference detection provided in the recording processing unit 212 has been described, but the present invention is not limited thereto, and for example, autofocus control of the contrast detection method may be performed.

[0022] The lens device 100 in the present embodiment is an inner focus (rear focus) type zoom lens. In an inner focus type zoom lens, when the zoom position is changed (zoom is performed) in a state of being in focus for a certain subject distance, the position of the image plane fluctuates and the focus becomes blurred. Therefore, in order to correct the fluctuation of the image plane position during zooming, the lens control unit 115 drives and controls the first focus lens group 113 and the second focus lens group 114 (zoom tracking control) using the locus data of the focus position stored in the memory 116.

[0023] Next, with reference to FIGS. 2(a) and 2(b), the relationship between the zoom position for each subject distance and the positions of the first focus lens group 113 and the second focus lens group 114 will be described. FIGS. 2(a) and 2(b) are diagrams showing the relationship between the zoom position for each subject distance and the respective positions of the first focus lens group 113 and the second focus lens group 114. In FIGS. 2(a) and 2(b), the horizontal axis represents the zoom position, and the vertical axis represents the positions of the first focus lens group 113 and the second focus lens group 114 (the first focus position and the second focus position), respectively. The curves shown by solid lines indicate the relationship between the zoom position and the focus position for maintaining focus at each subject distance. The memory 116 stores curves corresponding to each of a plurality of representative subject distances.

[0024] When the subject distance coincides with the representative subject distance, by reading out the data of the in-focus position corresponding to the representative subject distance and the zoom position, it is possible to obtain the target in-focus position to which the first focus lens group 113 and the second focus lens group 114 should be moved. Further, for subject distances other than the representative subject distance, the target in-focus position can be obtained by calculation (linear interpolation) using the in-focus position corresponding to the representative subject distance in the vicinity of that subject distance. Here, although the curves have been described as an example, the memory 116 may store data of representative points that can draw these curves by approximation.

[0025] Next, with reference to FIGS. 3(a) and 3(b), a method for calculating the in-focus positions of the first focus lens group 113 and the second focus lens group 114 in the case other than the representative subject distance will be described. FIGS. 3(a) and 3(b) are explanatory diagrams of a method for calculating the respective in-focus positions of the first focus lens group 113 and the second focus lens group 114 in the case other than the representative subject distance. In FIGS. 3(a) and 3(b), the horizontal axis represents the zoom position, and the vertical axis represents the first focus position and the second focus position, respectively. In each of FIGS. 3(a) and 3(b), the left side shows the entirety of the in-focus position trajectory data, and the right side shows an enlarged part (the part surrounded by a frame) of the trajectory data.

[0026] Here, a case of obtaining a focusing position at a zoom position y between a wide-side zoom position x and a tele-side zoom position z at a subject distance A' between a subject distance A and a subject distance B will be described. First, data on the focusing positions at the subject distance A and the subject distance B at the wide-side zoom position x are read, and the ratio b / a of the difference a between the subject distances A and B and the difference b between the subject distances A and A' is calculated. Then, using these focusing positions and the ratio b / a, the focusing position at the subject distance A' at the wide-side zoom position x is calculated.

[0027] Similarly, data on the focusing positions at the subject distance A and the subject distance B at the tele-side zoom position z are read. The ratio b' / a' of the difference a' between the subject distances A and B and the difference b' between the subject distances A and A' is the same as the ratio b / a. Then, using the focusing positions and the ratio b' / a' (= b / a), the focusing position at the subject distance A' at the tele-side zoom position z is calculated.

[0028] Next, a zoom movement amount l, which is the difference between the zoom position x and the zoom position y, and a zoom movement amount m, which is the difference between the zoom position y and the zoom position z, are calculated. Then, using the focusing positions at the wide-side and tele-side zoom positions x and z at the subject distance A' and the ratio l / (l + m) of the above distances, the focusing position at the zoom position y at the subject distance A' is calculated. By applying this calculation to both the first focus lens group 113 and the second focus lens group 114, the focusing positions of the first focus lens group 113 and the second focus lens group 114 can be calculated.

[0029] Next, with reference to FIG. 4, the control method in this embodiment will be described. FIG. 4 is a flowchart of the control method (control method when starting to drive each focus lens) in this embodiment. Each step in FIG. 4 is mainly executed by the lens control unit 115 based on a command from the camera control unit 216. However, this embodiment is not limited to this, and the camera control unit 216 may execute at least a part of each step executed by the lens control unit 115.

[0030] First, in step S401, the lens control unit 115 determines whether the focus drive factor is a drive command for focusing. If it is a drive command for focusing, the process proceeds to step S402. On the other hand, if it is a drive command other than for focusing, the process proceeds to step S406. Here, the drive command for focusing indicates a command by an operation for changing the target subject distance. For example, autofocus (AF), manual focus (MF), focus preset, etc. are applicable. On the other hand, the drive command other than for focusing indicates a command by an operation for operating the focus lens group without changing the target subject distance. For example, zoom tracking control associated with a zoom operation is applicable.

[0031] In step S402, the lens control unit 115 acquires the current zoom position detected by the zoom position detection unit 117. Subsequently, in step S403, the lens control unit 115 performs an operation to change the target subject distance according to the drive command for focusing.

[0032] Subsequently, in step S404, the lens control unit 115 determines the target positions of the first focus lens group 113 and the second focus lens group 114. The target positions can be determined based on the current zoom position acquired in step S402, the subject distance calculated in step S403, and the trajectory data of the in-focus position stored in the memory 116. Note that the method for determining the target positions is as described with reference to FIG. 3. Subsequently, in step S405, the lens control unit 115 performs drive control (performs synchronous control) to synchronize the first focus lens group 113 and the second focus lens group 114. Thereby, the aberration state during the drive of each focus lens group can be kept good. Note that the details of the processing during synchronous control will be described later.

[0033] In step S406, the lens control unit 115 acquires the current zoom position in the same manner as in step S402. Subsequently, in step S407, the lens control unit 115 refers to the currently targeted subject distance. Here, since it is not a drive command for focusing, unlike step S403, the arithmetic processing of the subject distance is not performed.

[0034] Subsequently, in step S408, the lens control unit 115 determines the target positions of the first focus lens group 113 and the second focus lens group 114. The target positions are determined based on the current zoom position acquired in step S406, the subject distance acquired in step S407, and the trajectory data of the in-focus position stored in the memory 116. This process is the same as step S404. Subsequently, in step S409, the lens control unit 115 drives and controls the first focus lens group 113 and the second focus lens group 114 asynchronously (performs asynchronous control). Thereby, the in-focus state during driving can be maintained well. The details of the processing during asynchronous control will be described later.

[0035] Here, synchronous control is control for determining the position of one of the first focus lens group 113 or the second focus lens group 114 using the position information of at least one of the first focus lens group 113 or the second focus lens group 114. On the other hand, asynchronous control is control for determining the position of one of the first focus lens group 113 or the second focus lens group 114 without using the position information of at least one of the first focus lens group 113 or the second focus lens group 114.

[0036] Next, with reference to FIGS. 5(a) and 5(b), the aberration-priority synchronous control in this embodiment will be described. FIG. 5(a) is a flowchart when driving and controlling the first focus lens group 113 synchronously with aberration priority (aberration-priority synchronous control).

[0037] First, in step S501a, the lens control unit 115 refers to the current position and speed of the first focus lens group 113. The current position and speed may be obtained based on the data detected by the position sensor (feedback control) or based on the drive command signal (open control).

[0038] Subsequently, in step S502a, the lens control unit 115 calculates the driving speed of the first focus lens group 113. When the current speed referred to in step S501a has not reached the target speed, the driving speed is a value obtained by adding a predetermined acceleration to the current speed. Also, when the current position enters a range less than a predetermined value with respect to the target position, the driving speed is a value obtained by subtracting a predetermined deceleration from the current speed. If neither case applies, the current speed is maintained.

[0039] Subsequently, in step S503a, the lens control unit 115 calculates the drive command position of the first focus lens group 113 according to the driving speed calculated in step S502a with respect to the current position referred to in step S501a. The drive command position calculated here is different from the final drive target position and indicates the position where the first focus lens group should be at the current time or after a short time.

[0040] Subsequently, in step S504a, the lens control unit 115 drives and controls the first focus lens group 113 based on the drive command position calculated in step S503a. The drive control method may be either by a feedback loop or by an open loop.

[0041] Subsequently, in step S505a, the lens control unit 115 determines whether the first focus lens group 113 has reached the final target position. If the first focus lens group 113 has reached the target position, this flow ends. On the other hand, if the first focus lens group 113 has not reached the target position, it returns to step S501a.

[0042] Figure 5(b) is a flowchart when the second focus lens group 114 is synchronously driven (aberration-priority synchronous control). First, in step S501b, the lens control unit 115 refers to the zoom position detected by the zoom position detection unit 117. Subsequently, in step S502b, the lens control unit 115 refers to the current position of the first focus lens group 113. The current position may be either the data detected by the position sensor or the drive command position calculated in step S503a.

[0043] Subsequently, in step S503b, the lens control unit 115 calculates the drive command position of the second focus lens group 114. The drive command position can be calculated based on the zoom position acquired in step S501b, the position of the first focus lens group 113 acquired in step S502b, and the trajectory information of the in-focus position stored in the memory 116. The drive command position calculated here is the position of the second focus lens group 114 corresponding to the in-focus position calculated based on the zoom position and the position of the first focus lens group 113 (the positional relationship described with reference to FIG. 3). By controlling to this position, it is possible to drive and control the first focus lens group 113 and the second focus lens group 114 in a synchronous positional relationship, and focusing can be performed in a state with less aberration.

[0044] Subsequently, in step S504b, the lens control unit 115 drives and controls the second focus lens group 114 based on the drive command position calculated in step S503b. The drive control method may be either by a feedback loop or by an open loop.

[0045] Subsequently, in step S505b, the lens control unit 115 determines whether the first focus lens group 113 and the second focus lens group 114 have reached their final target positions. If the first focus lens group 113 and the second focus lens group 114 have reached the target positions, this flow ends. On the other hand, if the first focus lens group 113 or the second focus lens group 114 has not reached the target position, the process returns to step S501b. In this embodiment, since the second focus lens group 114 is synchronously controlled in a form that follows the first focus lens group 113, the completion of the driving of the first focus lens group 113 is confirmed based on the driving end condition of the second focus lens group 114.

[0046] In this embodiment, an example in which the second focus lens group 114 synchronizes according to the first focus lens group 113 has been described, but the present invention is not limited to this, and the first focus lens group 113 may be synchronously controlled according to the second focus lens group 114. For example, a method of setting the focus lens group with higher focus sensitivity as the first focus lens group 113 can be considered as to which of the plurality of focus lens groups is the first focus lens group 113. Also, in this embodiment, an example of obtaining the driving position and performing driving control has been described, but driving control may be performed by obtaining the driving speed.

[0047] Next, with reference to FIGS. 6(a) and 6(b), the focus priority asynchronous control in this embodiment will be described. FIG. 6(a) is a flowchart when the first focus lens group 113 is asynchronously controlled with focus priority (focus priority asynchronous control). Note that since the flow of FIG. 6(a) is the same as the flow of FIG. 5(a), the description thereof is omitted. FIG. 6(b) is a flowchart when the second focus lens group 114 is asynchronously controlled with focus priority (focus priority asynchronous control). In steps S601b to S605b, the same processing as that for the first focus lens group 113 in steps S501a to S505a is performed on the second focus lens group 114.

[0048] Thus, in asynchronous control, drive control is performed without considering the positional relationship between the first focus lens group 113 and the second focus lens group 114. Asynchronous control is performed in the case of zoom tracking control. Even if a delay occurs in the drive control of the first focus lens group 113, it is possible to drive the second focus lens group 114 without being affected. Thereby, the responsiveness of the zoom focus correction drive can be enhanced.

[0049] Next, with reference to FIGS. 7(a) and 7(b), the difference between synchronous control and asynchronous control will be described. FIGS. 7(a) and 7(b) are explanatory diagrams of the difference between synchronous control and asynchronous control. Here, in order to explain the effect of asynchronous control, a case where synchronous control and asynchronous control are performed during zoom tracking control will be compared.

[0050] FIG. 7(a) shows an example in the case where synchronous control is performed during zoom tracking control. In this example, a case where the zoom position changes from time T1 to time T3 when the target subject distance is 5 m is shown. Focusing on the first focus lens group 113, from time T1 to time T2, the change in the slope of the target position becomes large. Such a change in slope can occur due to a plurality of factors such as a change in the zoom operation amount or an inflection point of the control curve of the zoom tracking control. At this time, if the target position is completely followed, the acceleration and speed may become too large, and vibrations and noises during driving may occur. Therefore, in order to limit the acceleration and speed in view of the weight of the lens and the driving conditions, a delay occurs in the zoom tracking control (in the case of the example in FIG. 7(a), the in-focus position is 4.9 m at time T2).

[0051] At this time, focusing on the second focus lens group 114, when synchronous control is performed, the first focus lens group 113 is at a focusing position of 4.9 m at time T2. Therefore, similarly, the command position of the second focus lens group 114 is calculated aiming at a focusing position of 4.9 m at time T2. Accordingly, at time T2, both the first focus lens group 113 and the second focus lens group 114 are controlled to positions when focusing on a subject of 4.9 m, and a 10-cm focus shift occurs due to the zoom operation.

[0052] FIG. 7(b) shows an example of performing asynchronous control during zoom tracking control. Note that since the movement of the first focus lens group 113 is the same as that in FIG. 7(a), the description thereof is omitted. Since the second focus lens group 114 is controlled asynchronously, it attempts to follow the target position within a predetermined acceleration / speed range regardless of the movement of the first focus lens group 113. In the case of this example, since the amount of change in the inclination is smaller than the locus of the target position of the first focus lens group 113, it can be controlled so that the target position and the command position substantially coincide.

[0053] Accordingly, at time T2, the first focus lens group 113 is controlled to a position when focusing on a subject of 4.9 m, and the second focus lens group 114 is controlled to a position when focusing on a subject of 5.0 m. For example, when the focus sensitivities (the amount of change in the image plane position per unit displacement) of the first focus lens group 113 and the second focus lens group 114 are the same, it will focus at a position of 4.95 m, and the focus shift due to the zoom operation is reduced to 5 cm. At this time, the deviation in the positional relationship between the first focus lens group 113 and the second focus lens group 114 affects the deterioration of the aberration state. However, since focus correction is prioritized over the aberration state during zoom tracking control, asynchronous control is performed.

[0054] The control device (lens control unit 115) of this embodiment controls a first focus drive unit 119 and a second focus drive unit 120 that drive a first focus lens group 113 and a second focus lens group 114, respectively. The control device has a drive amount calculation unit that periodically calculates the drive speed or drive position of each of the first focus drive unit 119 and the second focus drive unit 120. The drive amount calculation unit varies the calculation method of the drive speed or drive position depending on whether each focus lens group is driven when focusing or when not focusing. Here, the case of driving each focus lens group when not focusing is a case where each focus lens group is moved without substantially changing the focal length, such as in a zoom operation or an aberration variable operation described later.

[0055] Preferably, when driving each focus lens group when focusing, the drive amount calculation unit performs synchronous control on each focus lens group. On the other hand, when driving each focus lens group when not focusing, the drive amount calculation unit performs asynchronous control on each focus lens group. Here, synchronous control is control for determining the position of the other focus lens group using the position information of at least one of the focus lens groups. Asynchronous control is control for determining the position of the other focus lens group without using the position information of at least one of the focus lens groups.

[0056] Preferably, when driving each focus lens group when not focusing, the drive amount calculation unit calculates the drive speed or drive position based on the position of the operation unit (zoom operation unit 122) and the focus tracking data indicating the positional relationship for each predetermined subject distance. Also preferably, when driving each focus lens group when focusing, the drive amount calculation unit corrects the drive speed or drive position of the other focus lens group based on the drive position of one focus lens group, the position of the operation unit, and the focus tracking data.

[0057] As described above, according to this embodiment, by performing asynchronous control during zoom tracking control, even when a control delay occurs in the first focus lens group 113, it is possible to perform control without affecting the second focus lens group 114. Therefore, an effect of reducing the delay in zoom focus correction can be obtained.

Embodiment

[0058] Next, Embodiment 2 of the present invention will be described. In this embodiment, a single-focus lens in which the lens device does not have a zoom function, and the positional relationship of a plurality of focus lenses is variable according to the operation by the aberration amount operation unit 121, and a function of deliberately generating aberration (changing the aberration amount) will be described. By making the aberration amount variable, the user can control the expression of blurriness and perform an impressive video expression.

[0059] First, referring to FIG. 8, the imaging device in this embodiment will be described. FIG. 8 is a block diagram of an imaging device (camera system) 10a in this embodiment. The imaging device 10a is a lens interchangeable camera system configured to include a camera body 200 and a lens device (single-focus lens) 100a detachable from the camera body 200a. The lens device 100a of this embodiment is a single-focus lens, and the zoom lens 111 and the zoom position detection unit 117 do not exist. The aberration amount operation unit 121 is an operation member having a function of changing the positional relationship between the first focus lens group 113 and the second focus lens group 114 to change the aberration amount. Note that the aberration amount set here is read by the lens control unit 115, and the first focus lens group 113 and the second focus lens group 114 are driven and controlled using the first focus drive unit 119 and the second focus drive unit 120.

[0060] Next, with reference to FIGS. 9(a) and 9(b), the relationship between the amount of aberration for each subject distance and the positions of the first focus lens group 113 and the second focus lens group 114 will be described. FIGS. 9(a) and 9(b) are diagrams showing the relationship between the amount of aberration for each subject distance and the respective positions of the first focus lens group 113 and the second focus lens group. This relationship is obtained by replacing the zoom position in FIG. 2 with the amount of aberration, and is data used for control (aberration variable control) to change the amount of aberration while maintaining the in-focus state when the aberration amount operation unit is operated.

[0061] In the case of the zoom tracking control described in the first embodiment, the focus shift due to the zoom operation is corrected by the first focus lens group 113 and the second focus lens group 114. On the other hand, in the case of the aberration variable control of this embodiment, the focus shift due to the movement of the first focus lens group 113 and the focus shift due to the movement of the second focus lens group 114 cancel each other out. Note that the method for calculating the in-focus position and the control method under each condition are the same as those obtained by replacing the zoom positions in FIGS. 3 to 6 with the amount of aberration, and thus the description thereof is omitted.

[0062] Next, with reference to FIGS. 10(a) and 10(b), the difference between the synchronous control and the asynchronous control in this embodiment will be described. FIGS. 10(a) and 10(b) are explanatory diagrams of the difference between the synchronous control and the asynchronous control in this embodiment. Here, in order to explain the effect of the asynchronous control, the case where synchronous control and asynchronous control are performed during the aberration variable control will be compared. FIG. 10(a) is an example of performing synchronous control during the aberration variable control. Note that the movement of the first focus lens group 113 is the same as that in FIG. 7(a) described in the first embodiment.

[0063] Focusing on the second focus lens group 114, when synchronous control is being performed, the first focus lens group 113 is at the in-focus position of 4.9 m at time T2. Therefore, similarly, the command position of the second focus lens group 114 is calculated aiming at the in-focus position of 4.9 m at time T2.

[0064] As in the case of FIG. 10(a), when the second focus lens group 114 is controlled to positions corresponding to 5.0 m at time T1, 4.9 m at time T2, and 5.0 m at time T3, a reversal of the driving direction occurs, leading to vibrations and noises during driving. In the aberration variable control of this embodiment, since the first focus lens group 113 and the second focus lens group 113 are often driven in different driving directions, if synchronous control is performed during aberration variable control, as shown in the example, there is a high possibility of following a complex driving trajectory.

[0065] FIG. 10(b) is an example of performing asynchronous control during aberration variable control. Similar to FIG. 7(a) of Embodiment 1, since the second focus lens group 114 is asynchronously controlled, it attempts to follow the target position within a predetermined acceleration and speed range regardless of the movement of the first focus lens group 113. In the case of this example, since the amount of change in the inclination is smaller compared to the trajectory of the target position of the first focus lens group 113, it is possible to control such that the target position and the command position substantially coincide. Therefore, compared to synchronous control, in the case of asynchronous control, it is possible to reduce the focus fluctuation during aberration variable control and the vibrations and noises during driving.

[0066] As described above, according to this embodiment, by performing asynchronous control during aberration variable control, even when a control delay occurs in the first focus lens group 113, it is possible to control without affecting the second focus lens group 114. Further, in this embodiment, in addition to the effect of reducing the delay in focus correction, an effect of reducing the vibrations and noises during driving can be obtained.

Embodiment

[0067] Next, Embodiment 3 of the present invention will be described. In this embodiment, an example of performing synchronous control with priority given to focus when driving a plurality of focus lenses with a driving command that is not for focusing in the zoom lens of Embodiment 1 will be described.

[0068] First, with reference to FIGS. 11(a) and 11(b), the sensitivities of the first focus lens group 113 and the second focus lens group 114 will be described. FIGS. 11(a) and 11(b) are diagrams showing the sensitivities of the first focus lens group 113 and the second focus lens group 114 for each subject distance. FIG. 11(a) shows the sensitivity of the first focus lens group 113, and FIG. 11(b) shows the sensitivity of the second focus lens group 114. In FIGS. 11(a) and 11(b), the vertical direction indicates the change in the zoom position, and the horizontal direction indicates the change in the focus lens position. From this data, the amount of change in the image plane position caused by a predetermined movement amount of the focus lens can be obtained at each zoom / focus position. This data is stored in the memory 116. In the example of FIG. 11, an example having the sensitivities of a plurality of focus lenses is shown, but the ratio of the sensitivities of the plurality of focus lenses may be set under each condition such as the zoom position and the subject distance.

[0069] In this embodiment, by using the sensitivity information shown in FIG. 11, a focus priority synchronization control is performed in which the control delay of one focus lens group that occurs during zoom tracking control is corrected by the other focus lens group.

[0070] Next, with reference to FIG. 12, the control method in this embodiment will be described. FIG. 12 is a flowchart of (control method) when starting to drive each focus lens in this embodiment. Each step in FIG. 12 is mainly executed by the lens control unit 115 based on a command from the camera control unit 216. Since steps S401 to S408 in FIG. 12 are the same as those in FIG. 4, their descriptions will be omitted.

[0071] In step S1209, when driving and controlling a plurality of focus lenses other than during focusing (such as zoom tracking control), the lens control unit 115 performs focus priority synchronization control on the first focus lens group 113 and the second focus lens group 114.

[0072] Next, with reference to FIGS. 13(a) and 13(b), focus-priority synchronous control will be described. FIGS. 13(a) and 13(b) are flowcharts for synchronously driving and controlling the first focus lens group 113 and the second focus lens group 114 with focus priority (focus-priority synchronous control).

[0073] FIG. 13(a) is a flowchart for synchronously controlling the first focus lens group 113 with focus priority. In FIG. 13(a), steps S501a to S505a are the same as those in FIG. 5 described in the first embodiment, and thus their descriptions are omitted.

[0074] FIG. 13(b) is a flowchart for synchronously controlling the second focus lens group 114 with focus priority. In FIG. 13(b), steps S501b and S502b are the same as those in FIG. 5 of the first embodiment, and thus their descriptions are omitted.

[0075] In step S1301b, the lens control unit 115 calculates the control delay amount of the first focus lens group 113. The control delay amount can be calculated based on the zoom position acquired in step S501b, the current position of the first focus lens group 113 acquired in step S502b, and the focus position data for each subject distance stored in the memory 116. Here, the control delay amount refers to the amount by which the control command position or the actual lens position is deviated from the ideal position for maintaining the in-focus state in zoom tracking control due to the acceleration and speed limitations of the first focus drive unit 119.

[0076] Subsequently, in step S1302b, the lens control unit 115 calculates the correction amount for the second focus lens group 114 based on the control delay amount of the first focus lens group 113 calculated in step S1301b and the sensitivity data stored in the memory 116. For example, consider a case where a control delay amount of 10 um (-10 um) has occurred in the first focus lens group 113. At this time, if the sensitivities of the first focus lens group 113 and the second focus lens group 114 are in a ratio of 2:1, the second focus lens group 114 has a correction amount of 20 um (+20 um).

[0077] Subsequently, in step S1303b, the lens control unit 115 calculates the drive command position for the second focus lens group 114 in consideration of the correction amount calculated in step S1302b. Here, if all of the correction amount is reflected in the drive command position, it may exceed the acceleration and speed limits of the second focus drive unit 120. Therefore, it is desirable to provide a limit in the calculation of the drive command position so as not to exceed a predetermined acceleration and speed range. Since the subsequent steps S504b and S505b are the same as those in FIG. 5 described in the first embodiment, their descriptions are omitted.

[0078] In this embodiment, an example in which the second focus lens group 114 corrects the control delay of the first focus lens group 113 has been described. However, the first focus lens group 113 may correct the control delay of the second focus lens group 114. Alternatively, depending on the situation, the focus lens group to be corrected may be dynamically switched, such as the other focus lens correcting the control delay of one of the focus lens groups that has a delay in the zoom tracking control.

[0079] Next, with reference to FIGS. 14(a) and 14(b), the difference between the aberration-priority synchronization control and the focus-priority synchronization control in this embodiment will be described. FIGS. 14(a) and 14(b) are explanatory diagrams of the difference between the aberration-priority synchronization control and the focus-priority synchronization control in this embodiment. FIG. 14(a) shows an example of performing aberration-priority synchronization control. Since it is the same as FIG. 7 described in Embodiment 1, the description thereof is omitted. FIG. 14(b) shows an example of performing focus-priority synchronization control. The movement of the first focus lens group 113 is the same as that in FIG. 7 described in Embodiment 1. At time T2, a control delay occurs with respect to the position corresponding to the target in-focus position of 5.0 m, and it is controlled to the position corresponding to the in-focus position of 4.9 m.

[0080] At this time, the second focus lens group 114 is controlled to the position that corrects the control delay occurring in the first focus lens group at time T2. The correction position is the control position obtained in step S1302b of FIG. 13. In this example, at time T2, it is controlled to the position corresponding to the in-focus position of 5.1 m, and is controlled to the position that suppresses the focus variation caused by the control delay of the first focus lens group 113.

[0081] Preferably, when the driving amount calculation unit (lens control unit 115) drives each focus lens group when focusing, it performs first synchronization control on each focus lens group. On the other hand, when the driving amount calculation unit drives each focus lens group when not focusing, it performs second synchronization control on each focus lens group. Here, the first synchronization control is a control with less change in the aberration amount than the second synchronization control, and the second synchronization control is a control with less change in the focus position than the first synchronization control. Preferably, when the driving amount calculation unit drives each focus lens group when not focusing, it calculates the driving speed or driving position of the other focus lens group based on the position of one focus lens group, the position of the operation unit, the focus trajectory data, and the sensitivity data.

[0082] As described above, according to this embodiment, by performing focus-priority synchronization control during zoom tracking control, even when a control delay occurs in one focus lens group, it is possible to suppress focus fluctuations using the other focus lens group. As a result, it becomes possible to reduce focus fluctuations during the zoom operation even more.

[0083] (Other Embodiments) The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiment 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 (for example, ASIC) that realizes one or more functions.

[0084] 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 control a plurality of focus lens groups to improve the focusing accuracy during the zoom operation.

[0085] As described above, the preferred embodiments of the present invention have been described, but the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist thereof.

[0086] For example, the control of each embodiment is mainly performed by the lens control unit, but it is not limited thereto, and at least a part of the control may be performed by the camera control unit. Further, the lens device of each embodiment has two focus lens groups, namely, the first focus lens group and the second focus lens group, but it is not limited thereto, and it may have three or more focus lens groups.

Description of Reference Numerals

[0087] 113 First focus lens group 114 Second focus lens group 115 Lens control unit (drive amount calculation unit) 119 First focus drive unit 120 Second focus drive unit

Claims

1. A control device for controlling a first focus drive unit and a second focus drive unit which move a first focus lens group and a second focus lens group, respectively, in an optical axis direction, comprising: a drive amount calculation unit that periodically calculates a drive speed or a drive position of each of the first focus drive unit and the second focus drive unit, The drive amount calculation unit When the first focus lens group and the second focus lens group are moved during focusing, a synchronous control is performed on the first focus drive unit and the second focus drive unit; When the first focus lens group and the second focus lens group are moved during magnification change, asynchronous control is performed on the first focus drive unit and the second focus drive unit; In the synchronous control, the first focus driver is controlled using information about a position and a speed of the first focus lens group, and the second focus driver is controlled using information about the position of the first focus lens group. A control device characterized in that, in the asynchronous control, the first focus drive unit is controlled using information regarding the position and speed of the first focus lens group, and the second focus drive unit is controlled using information regarding the position and speed of the second focus lens group without using information regarding the position of the first focus lens group.

2. A control device that controls a first focus drive unit and a second focus drive unit that move a first focus lens group and a second focus lens group, respectively, in an optical axis direction, a drive amount calculation unit that periodically calculates a drive speed or a drive position of each of the first focus drive unit and the second focus drive unit, The drive amount calculation unit when moving the first focus lens group and the second focus lens group during focusing, a first synchronization control is performed on the first focus drive unit and the second focus drive unit; when moving the first focus lens group and the second focus lens group during magnification change, a second synchronization control is performed on the first focus drive unit and the second focus drive unit; the first synchronous control is a control that causes a smaller change in the amount of aberration than the second synchronous control, The control device according to claim 1, wherein the second synchronous control causes less change in focus position than the first synchronous control.

3. The control device according to claim 1, characterized in that, when moving the first focus lens group and the second focus lens group during magnification, the drive amount calculation unit calculates the drive speed or the drive position based on a position of an operation unit that determines a positional relationship between the first focus drive unit and the second focus drive unit and focusing trajectory data that indicates the positional relationship for each specified subject distance.

4. The control device described in claim 2, characterized in that when the first focus lens group and the second focus lens group are moved during magnification, the drive amount calculation unit calculates the drive speed or the drive position of the other of the first focus drive unit or the second focus drive unit based on the position of one of the first focus drive unit or the second focus drive unit, the position of an operation unit that determines the positional relationship between the first focus drive unit and the second focus drive unit, focusing trajectory data that indicates the positional relationship for each specified subject distance, and sensitivity data that indicates the sensitivity of the first focus lens group and the second focus lens group for each position of the first focus lens group and the second focus lens group.

5. The control device described in claim 3 or 4, characterized in that when the first focus lens group and the second focus lens group are moved during focusing, the drive amount calculation unit corrects the drive speed or the drive position of the other of the first focus drive unit or the second focus drive unit based on the drive position of the other of the first focus drive unit or the second focus drive unit, the position of the operation unit, and the focusing trajectory data.

6. A lens device comprising: a control device as described in any one of claims 1 to 5; and the first focus lens group and the second focus lens group.

7. 7. The lens device according to claim 6, wherein the distance between the first focus lens group and the second focus lens group changes during focusing.

8. 8. The lens apparatus according to claim 6, further comprising an operation unit for determining a positional relationship between the first focus lens group and the second focus lens group.

9. 9. The lens device according to claim 8, wherein the operation section is a zoom operation section for performing a zoom operation.

10. 9. The lens device according to claim 8, wherein the operation section is an aberration amount operation section for changing an amount of aberration.

11. 11. The lens device according to claim 6, which is detachable from a camera body.

12. A control method for controlling a first focus drive unit and a second focus drive unit which move a first focus lens group and a second focus lens group, respectively, in an optical axis direction, comprising: a drive amount calculation step of periodically calculating a drive speed or a drive position of each of the first focus drive unit and the second focus drive unit; a control step of controlling the first focus driver and the second focus driver based on the driving speed or the driving position, In the drive amount calculation step, When the first focus lens group and the second focus lens group are moved during focusing, a synchronous control is performed on the first focus drive unit and the second focus drive unit; When the first focus driving unit and the second focus driving unit are moved during magnification change, asynchronous control is performed on the first focus driving unit and the second focus driving unit; In the synchronous control, the first focus driver is controlled using information about a position and a speed of the first focus lens group, and the second focus driver is controlled using information about the position of the first focus lens group. The control method is characterized in that, in the asynchronous control, the first focus drive unit is controlled using information regarding the position and speed of the first focus lens group, and the second focus drive unit is controlled using information regarding the position and speed of the second focus lens group without using information regarding the position of the first focus lens group.

13. A control method for controlling a first focus drive unit and a second focus drive unit which move a first focus lens group and a second focus lens group, respectively, in an optical axis direction, comprising: a drive amount calculation step of periodically calculating a drive speed or a drive position of each of the first focus drive unit and the second focus drive unit; a control step of controlling the first focus driver and the second focus driver based on the driving speed or the driving position, In the drive amount calculation step, when moving the first focus lens group and the second focus lens group during focusing, a first synchronization control is performed on the first focus drive unit and the second focus drive unit; when moving the first focus lens group and the second focus lens group during magnification change, a second synchronization control is performed on the first focus drive unit and the second focus drive unit; the first synchronous control is a control that causes a smaller change in the amount of aberration than the second synchronous control, The control method according to claim 1, wherein the second synchronous control causes less change in focus position than the first synchronous control.

14. A program for causing a computer to execute the control method according to claim 12 or 13.

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