Lens control device, lens device, and imaging device

Abstract

To solve the problem in which: the temperature drift of a zoom group of an imaging apparatus narrows a focus driving range, and thereby a margin at a control end may be changed and a focus may not be obtained at a desired subject distance.SOLUTION: A lens control unit controls an imaging optical system comprising: a first variable magnification lens (120) that moves in association with zooming; a second variable magnification lens (140) whose position is controlled based on the position of the first variable magnification lens; and a focus lens (105) that adjusts a focal position. The lens control unit comprises: position detection means (116a, 116b) that detect the position of the second variable magnification lens; and setting means (118) that sets the driving range of the focus lens based on the position of the second variable magnification lens.SELECTED DRAWING: Figure 5

Description

[Technical Field]

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

[0002] The lens barrel, which mechanically supports the multiple lens groups within an imaging device, is made up of structural components such as molded components and metal components. The structural components that make up the lens barrel can mechanically expand and contract due to thermal expansion caused by factors such as an increase in the ambient temperature of the imaging device or an increase in temperature within the imaging device itself. This expansion and contraction changes the relative positions of the lenses that make up the imaging optical system, resulting in shifts in the focus position and changes in the lens's operating range before and after the mechanical expansion and contraction.

[0003] To address these issues, Patent Documents 1 and 2 propose technologies that incorporate a temperature detection sensor into the imaging device body and correct the focus lens position, zoom lens position, and driving range based on temperature changes. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 3581513 [Patent Document 2] Patent No. 4857257 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, the trend toward 4K video has led to a trend toward larger lens barrels in order to achieve higher image quality through higher resolution and larger image sensors. At the same time, however, users have been demanding smaller imaging devices. As lens barrels continue to become smaller, it becomes necessary to increase the sensitivity of focus movement relative to lens movement (position sensitivity).

[0006] On the other hand, increasing the position sensitivity of the lens increases the impact on focus and lens drive range due to the movement of the lens group caused by the expansion and contraction of the structural components of the lens unit due to thermal expansion. In particular, the thermal expansion and contraction of mechanical components made up of molded components varies greatly from one unit to another. Therefore, even at the same temperature, the focus position and lens drive range can vary significantly from unit to unit, and in some cases, it can become impossible to focus on the desired subject.

[0007] The present invention provides a lens control device, a lens device, and an imaging device that achieve good focusing operability even when temperature expansion and contraction differ from one device to another. [Means for solving the problem]

[0008] According to one aspect of the present invention, there is provided a lens control device for an imaging optical system including a first variable magnification lens that moves with zooming, a second variable magnification lens whose position is controlled based on the position of the first variable magnification lens, and a focus lens that adjusts a focus position, the lens control device comprising: a position detection unit that detects the position of the second variable magnification lens; and a setting unit that sets a drive range of the focus lens based on the position of the second variable magnification lens. a position control means for controlling the position of the focus lens; Equipped with When the focus lens is stationary at a first position, if the setting means changes the drive range of the focus lens from a third range including the first position to a fourth range excluding the first position, the position control means maintains the focus lens at the first position. Other aspects of the present invention will become apparent from the following embodiments. [Effects of the Invention]

[0009] The present invention can provide a lens control device, a lens device, and an imaging device that achieve good focusing operability even when temperature expansion and contraction differs for each individual device. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram illustrating the configuration of an imaging device according to a first and second embodiment; [Figure 2] 1 is a flowchart showing zooming processing according to the first and second embodiments; [Figure 3] Auxiliary lens cam data [Figure 4] Focus lens cam data [Figure 5] 1 is a flowchart showing a process for setting a driving range of a focus lens according to a first embodiment; [Figure 6] Conceptual diagram showing the driving range of the focus lens [Figure 7] 10 is a flowchart showing a process for setting the driving range of a focus lens according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] First Embodiment 1 shows the configuration of a video camera (image capture device) according to an embodiment of the present invention. Although a video camera will be described in this embodiment, the present invention can also be applied to other image capture devices such as a digital still camera.

[0012] The imaging device shown in FIG. 1 has, as an imaging optical system, in order from the subject side (left side of the figure), a first fixed lens 101, a zoom lens 102, an aperture unit 103, an auxiliary lens 104, and a focus lens 105. The zoom lens (first variable magnification lens) 102 moves in the optical axis direction to change magnification. The auxiliary lens (second variable magnification lens) 104 moves in the optical axis direction according to the position of the zoom lens 102, thereby assisting in zooming by the zoom lens 102. The focus lens 105 is a focus compensator lens that combines the function of correcting movement of the focal plane associated with magnification change and the function of focusing to adjust the in-focus position.

[0013] The image sensor 106 is a photoelectric conversion element formed by a CCD sensor or a CMOS sensor, and captures an image of a subject formed by an imaging optical system. The CDS / AGC circuit 107 samples the output of the image sensor 106 and adjusts the gain. The camera signal processing circuit 108 converts the output signal of the CDS / AGC circuit 107 into a signal compatible with the recording device 109, and sends the image signal of a still image or a video signal of a moving image obtained by the conversion to the recording device 109. The recording device 109 controls the recording of the moving images and still images, and records the image signal and video signal on a recording medium (not shown). The recording medium can be a magnetic tape, a semiconductor memory, a DVD (Digital Versatile Disk), or the like.

[0014] The stepping motor drive circuit 110b controls the driving of the stepping motor 110a, which is a drive source that drives the zoom lens 102. A feed screw shaft 110c, which is an output shaft, is engaged with the stepping motor 110a. When the stepping motor 110a is driven, the feed screw shaft 110c rotates, and the meshing action between the feed screw shaft 110c and the rack drives the zoom lens 102 in the optical axis direction (the direction of the arrow in FIG. 1).

[0015] When the stepping motor 110a drives the zoom lens 102 to a target position, the stepping motor drive circuit 110b first sets the zoom lens 102 to a position (reference position) that serves as a reference for position control when the imaging device is started. Then, the stepping motor drive circuit 110b inputs a drive signal with the number of pulses required to move the zoom lens 102 from this reference position to the target position to the stepping motor. For this reason, the imaging device is provided with a reference position sensor for detecting whether the zoom lens 102 is located at the reference position. In this embodiment, the reference position sensor is configured by a photointerrupter in which a light-emitting element and a light-receiving element are integrated. A light-shielding portion provided on the lens holding frame is inserted between the light-emitting element and the light-receiving element of the photointerrupter, blocking light from the light-emitting element toward the light-receiving element, thereby detecting that the zoom lens 102 is located at the reference position. Note that the light-shielding member is provided on the telephoto side of the zoom lens 102. I'm in the zoneor wide-angle I'm in the zone mosquito Inspection Enables output do.

[0016] A position scale 115b for detecting the position of the zoom lens 102 is fixed to the holding frame of the zoom lens 102. A position sensor 115a is fixed to the lens barrel at a location opposite the position scale 115b. The position scale 115b has scale patterns, such as a magnetic pattern and an optical reflection pattern, generated in the optical axis direction, and the position sensor 115a reads magnetic signals, optical reflection signals, etc., corresponding to the position of the scale. This makes it possible to detect the position of the zoom lens 102 in the optical axis direction. A detection signal from the position sensor 115a is input to a microprocessor 118, which will be described later, and is used to control the position of the zoom lens 102.

[0017] The stepping motor drive circuit 111b controls the driving of the stepping motor 111a, which is a drive source that drives the auxiliary lens 104. A feed screw shaft 111c, which is an output shaft, is engaged with the stepping motor 111a. When the stepping motor 111a is driven, the feed screw shaft 111c rotates, and the auxiliary lens 104 is driven in the optical axis direction (the direction of the arrow in FIG. 1) by the engagement between the feed screw shaft 111c and the rack.

[0018] When the stepping motor 111a drives the auxiliary lens 104 to a target position, the stepping motor drive circuit 111b first sets the auxiliary lens 104 to a position (reference position) that serves as a reference for position control when the imaging device is started. Then, the stepping motor drive circuit 111b inputs a drive signal with the number of pulses required to move the auxiliary lens 104 from this reference position to the target position to the stepping motor. For this reason, the imaging device is provided with a reference position sensor for detecting whether or not the auxiliary lens 104 is located at the reference position. In this embodiment, the reference position sensor has the same configuration as the reference position sensor of the zoom lens 102, so a detailed description will be omitted. A photointerrupter, in which a light-emitting element and a light-receiving element are integrated, detects that the auxiliary lens 104 has been located at the reference position.

[0019] A position scale 116b for detecting the position of the auxiliary lens 104 is fixed to the holding frame of the auxiliary lens 104. A position sensor 116a is also fixed at a location facing the position scale 116b. The configurations of the position scale 116b and the position sensor 116a are similar to those of the position scale 115b and the position sensor 115a of the zoom lens 102, and therefore a description thereof will be omitted. A detection signal from the position sensor 116a is input to a microprocessor 118, which will be described later, and the detection result of the position of the auxiliary lens 104 in the optical axis direction is used to control the position of the auxiliary lens 104.

[0020] The focus drive circuit 114 includes a voice coil motor as a drive source and its drive circuit, and drives the focus lens 105 to a target position. A position scale 117b for detecting the position of the focus lens 105 is fixed to a holding frame of the focus lens 105, and a position sensor 117a is fixed at a location facing the position scale 117b. Scale patterns such as magnetic patterns and light reflection patterns are generated on the position scale 117b in the optical axis direction, and the position sensor 117a reads magnetic signals, light reflection signals, etc. corresponding to the scale position. This makes it possible to detect the position of the focus lens 105 in the optical axis direction. The detection signal from the position sensor 117a is input to a microprocessor 118 (described later), which feeds back position information of the focus lens 105 to form a servo control system.

[0021] In this embodiment, it is assumed that the focus lens is driven by a voice coil motor (VCM), but other types of actuators, such as a DC motor or an ultrasonic motor, can also be used. Furthermore, a stepping motor may be used as the focus drive source, and the position sensor 117a and scale 117b attached to the focus lens holding frame may be omitted. The focus lens position sensor 117a is necessary for forming a servo control system using a VCM, and is also necessary for acquiring the position of the focus lens 105. However, when a stepping motor is used as the drive source for the focus lens, the pulse count can be treated as position information.

[0022] Furthermore, the stopping accuracy of the drive source for the focus lens 105 is determined by using an actuator with higher stopping accuracy than the zoom lens 102 and auxiliary lens 104 described above. This allows for position correction of the zoom lens 102 and auxiliary lens 104, which will be described later. The required stopping accuracy can be determined based on the position sensitivity of the zoom lens 102 and auxiliary lens 104, the focal depth of the imaging optical system of the imaging device, and the like.

[0023] The microprocessor 118 functions as a control means for controlling the overall operation of the imaging apparatus in response to inputs from a zoom operation unit 119 and various operation switches such as a power switch and a recording switch (not shown).

[0024] The zoom operation unit 119 can be configured with a rocker lever or a button for instructing movement to the wide-angle side and a button for instructing movement to the telephoto side, an electronic ring that changes the zoom magnification by rotation, or the like. Note that multiple zoom operation units 119 may be provided. When these zoom operation units 119 are operated, operation signals indicating the operation direction and amount are output to the microprocessor 118. Based on this information, the microprocessor 118 calculates the drive speed and drive direction of the zoom lens 102 and auxiliary lens 104, and outputs drive commands to each drive circuit (110b, 111b) according to the calculation results, thereby moving the zoom lens 102 along the optical axis.

[0025] The memory 120 provided within the microprocessor 118 stores the positions of the telephoto end (tele end) and the wide-angle end (wide end) of the zoom lens 102 relative to a reference position. The stepping motors 110a and 111a are driven in response to forward and reverse signals input from the microprocessor 118 to the two stepping motor drive circuits 110b and 111b, respectively. The focus drive circuit 114 is driven by a control signal from the microprocessor 118. In this manner, the microprocessor 118 functions as a lens control unit that controls lens drive. The magnification change operation and accompanying focusing operation of the imaging optical system are performed by controlling the stepping motor 111a, which is the drive source of the auxiliary lens 104, and the focus drive circuit 114 using an electronic cam system that utilizes cam locus data, which is commonly used in video cameras and the like. The cam locus data is stored in the memory 120 of the microprocessor 118. The imaging optical system of this embodiment includes a zoom lens 102, an auxiliary lens 104, and a focus lens 105. In such an imaging optical system, the cam trajectory data generally used is auxiliary lens cam data indicating the positional relationship between the zoom lens 102 and the auxiliary lens 104, and focus cam data indicating the positional relationship between the zoom lens 102 and the focus lens 105. This embodiment will also describe this configuration. Note that there are no particular limitations on the drive method of the stepping motor used in this embodiment, and a 1-2 phase drive method or a 2-2 phase drive method may be used. Furthermore, the position sensitivities of the auxiliary lens 104 and the focus lens 105 are stored in the memory 120.

[0026] The aperture unit 103 is an aperture including a galvanometer type actuator (not shown). Drive It has a circuit 113, diaphragm blades that are driven to open and close by this actuator, and a position detection element 112 (Hall element) that detects the open / closed state of the diaphragm.

[0027] The microprocessor 118 controls the input luminance signal component so that it always has an appropriate value. Aperture drive circuit 113 Actuatoris feedback-controlled. At this time, the output from the position detection element 112 is amplified and further converted from an analog signal to a digital signal by an A / D conversion circuit (not shown) and input to the microprocessor 118 as information indicating the diaphragm open / close position. Based on this diaphragm position information, the microprocessor 118 sends an open / close signal to the drive circuit 113 to control the diaphragm 103 so that the luminance signal component is always at an appropriate value. The microprocessor 118 can also send an open / close signal to the diaphragm drive circuit 113 to position the diaphragm at a predetermined open / close position.

[0028] Focus operation unit 121 is an operating member that drives focus lens 105, and sends operation information such as the amount of operation and the operation speed to microprocessor 118. Microprocessor 118 realizes manual focus operation by outputting a drive command to focus lens drive circuit 114 based on the operation information from focus operation unit 121. Note that microprocessor 118 may perform focus detection based on a video signal from camera signal processing circuit 108, and output a drive command to focus lens drive circuit 114 based on the focus detection result.

[0029] The zoom drive control program executed by the microprocessor 118 will be described in detail below with reference to the flowchart of Fig. 2. The process (S201 to S216) in Fig. 2 is a process that is periodically repeated every cycle ΔT. This process starts when the power to the camera body is turned on, and is performed by the microprocessor 118 receiving outputs from the memory 120, zoom operation unit 119, and each position sensor (115a, 116a, 117a), etc., and controlling each drive circuit (110b, 111b, 114). This flow may also be started in response to switching from a playback mode in which a captured image is displayed or a setting mode in which various settings are made, to a capture mode in which capture is on standby.

[0030] In step S201, it is determined whether the zoom operation unit 119 has been operated (whether an operation signal has been input). If it has been operated, the process proceeds to step S202, where the target zoom speed Vz of the zoom lens 102 is acquired based on the information on the operation amount included in the operation signal. Thereafter, the process proceeds to step S203, where the zoom target position Zt is acquired. The zoom target position Zt is calculated based on the drive counter of the stepping motor drive circuit 110b. indicates If the current zoom position is Z and the control period is ΔT, it can be calculated using the following formula. (Formula 1) Zt=Z+Vz×ΔT

[0031] Next, the process proceeds to step S204. In S204, a drive target position of the auxiliary lens 104 is determined. FIG. 3 is a diagram showing the positional relationship between the zoom lens 102 and the auxiliary lens 104, and information corresponding to FIG. 3 is stored as auxiliary lens cam data in memory 120 within the microprocessor 118. In step S204, the auxiliary lens target position St corresponding to Zt is obtained based on Zt calculated by (Equation 1) and the auxiliary lens cam data.

[0032] Next, proceed to step S205 and the goal The speed Vs is calculated by the driving counter of the stepping motor driving circuit 111b. indicates The current position S of the auxiliary lens 104 is used to calculate based on the following (Equation 2). (Equation 2) Vs = (St - S) / ΔT

[0033] Next, the process proceeds to step S206, where subject distance L, which is the current distance to the subject, is obtained based on the focus lens position information input from position sensor 117a. Note that subject distance L is obtained by assuming that the subject is in focus at the detected focus lens position before the zoom lens is driven. Specifically, this is done by referring to the cam data stored in memory 120, the focus lens position, and the current zoom lens position Z.

[0034] Next, the process proceeds to step S207. In step S207, the drive target position of the focus lens 105 is determined. FIG. 4 shows focus cam data that indicates the positional relationship between the zoom lens 102 and the focus lens 105. The focus cam data is stored in the memory 120 within the microprocessor 118 as a plurality of table data for each of the discrete object distances L0 to Ln. The focus cam data corresponding to the object distance L obtained in step S206 is called from the memory 120. Note that, The next smallest and next largest subject distances The focus cam data for the object distance L may be calculated by interpolation from the focus cam data. 3 The focus lens target position Ft corresponding to the zoom target position Zt calculated by (Equation 1) is obtained.

[0035] Next, proceed to step S208, and the goal The velocity Vf is calculated based on the following (Equation 3) using the current position F of the focus lens 105 detected by the position sensor 117a. (Equation 3) Vf = (Ft - F) / ΔT

[0036] In step S209, the target position and target speed are sent to the stepping motor drive circuit 110b that drives the zoom lens 102, the stepping motor drive circuit 111b that drives the auxiliary lens 104, and the focus drive circuit 114 that drives the focus lens 105. This drives the zoom lens 102, the auxiliary lens 104, and the focus lens 105. Then, the process proceeds to step S210, where a driving flag f that indicates the drive status of the zooming operation is set.

[0037] On the other hand, if there is no input of an operation signal from the zoom operation unit 119 in step S201, the process proceeds to step S211, where the driving of each lens is stopped and a settling operation for settling each lens is controlled.

[0038] In step S211, a stop command to stop the zoom lens 102 is sent to the stepping motor drive circuit 110b, and in step S212, it is determined whether the drive of the zoom lens 102 has been stopped. If the drive of the zoom lens 102 has been stopped, the process proceeds to step S213. If the drive has not been stopped, the process returns to step S211, and a stop command is sent again to the stepping motor drive circuit 110b.

[0039] In step S213, the stop position of the auxiliary lens 104 is acquired, and after moving to the acquired stop position, driving of the auxiliary lens 104 is stopped. The method of calculating the stop position is the same as in step S204, and the stop position Ss of the auxiliary lens 104 is calculated using the stop position of the zoom lens 102 and the auxiliary lens cam data shown in FIG.

[0040] In step S214, the stop position of focus lens 105 is acquired, and after moving to the acquired stop position, driving of focus lens 105 is stopped. The method of calculating the stop position is the same as in step S207, and the stop position Fs of focus lens 105 is acquired using the stop position of zoom lens 102 and the focus cam data shown in FIG. 4. The operations of steps S211 to S214 perform settling operations for each lens (zoom lens 102, auxiliary lens 104, focus lens 105).

[0041] In step S215, the position of the auxiliary lens 104 is obtained from the output of the position sensor 116a and stored in the memory 120 as the stop position Ss of the auxiliary lens 104 during settling, and in the following step S216, the driving flag f set in step S210 is cleared.

[0042] In step S207, the focus target position is calculated as a position within the focus driving range. The focus lens driving range is set to include a position where the focus is focused on an object with an infinite subject distance (infinity position) and a position where the focus is focused on an object with the closest possible subject distance (close position), preferably with a margin between these positions. In other words, the control end on the infinity side of the focus lens is set outside the infinity position by a margin (opposite the close position), and the control end on the close position is set outside the close position by a margin (opposite the infinity position). However, if the position of the auxiliary lens deviates from its settling position due to temperature changes, depending on the amount of deviation and the position sensitivity of the auxiliary lens, either the infinity position or the close position may lose its margin relative to the control end or may fall outside the driving range. Therefore, in this embodiment, the focus driving range is set according to the position of the auxiliary lens 104. The program for setting the focus driving range will be described in detail using the flowchart of FIG. 5. This process is performed by the microprocessor 118 upon receiving outputs from the memory 120, the auxiliary lens position sensor 116a, etc. This process is also repeated periodically at cycles ΔT, and is performed in parallel with the flow of Fig. 2, but the cycle may be different from that of the flow of Fig. 2.

[0043] First, in S501, it is determined whether zoom driving is currently in progress based on the driving in progress flag. If the flag is not set, it is determined that zoom driving is not in progress and this process ends. If the flag is set and zoom driving is in progress, the process proceeds to step S502. In step S502, the stop position Ss of the auxiliary lens 104 at the time of settling, which was saved in step S215 of FIG. 2, is obtained from the memory 120. In the following step S503, the current position Sc of the auxiliary lens 104 is obtained from the position detection sensor 116a.

[0044] Next, the process proceeds to step S504. 2 The stop position Ss of the auxiliary lens 104 during settling acquired in step S50 3Based on the current position Sc of the auxiliary lens 104 acquired in step 1, the position difference ΔS, which is the amount of deviation in the position of the auxiliary lens 104, is calculated using the following (Equation 4). (Formula 4)ΔS = Sc - S

[0045] Next, the process proceeds to step S505, where the position sensitivity Ks of the auxiliary lens 104 is obtained from the memory 120. The position sensitivity Ks is the ratio between the movement amount of the auxiliary lens 104 and the movement amount of the image plane where the image is formed, and the higher the sensitivity, the larger the movement amount of the image plane even with a slight movement of the auxiliary lens. If the auxiliary lens 104 moves by ΔX, the image plane movement amount ΔP can be expressed as (Equation 5). (Equation 5) ΔP = ΔX × Ks

[0046] Next, the process proceeds to step S506, where the infinity position sensitivity Kff and the closest position sensitivity Kfn of the focus lens 105 are obtained from the memory 120. Because the position of the focus lens 105 changes depending on the subject distance, the position sensitivity of the focus lens 105 also varies depending on the subject distance. The infinity position sensitivity Kff is the position sensitivity of the focus lens 105 when focused at infinity. The closest position sensitivity Kfn is the position sensitivity of the focus lens 105 when focused at the closest position at which photography is possible. The position sensitivities Kff and Kfn are the ratio between the amount of movement of the focus lens 105 and the amount of movement of the image plane at which an image is formed; the higher the sensitivity, the greater the movement of the image plane even with a slight movement of the focus lens 105. If the auxiliary lens 104 moves by ΔY, the amount of image plane movement ΔQf at infinity can be expressed as (Equation 6), and the amount of image plane movement ΔQn at the closest position can be expressed as (Equation 7). (Equation 6) ΔQf = ΔY × Kff (Equation 7) ΔQn = ΔY × Kfn

[0047] In the next step S507, a correction amount is determined for the end (control end) of the driving range of the focus lens 105 due to the deviation of the auxiliary lens 104. The position difference ΔS of the auxiliary lens 104 obtained in the above process is applied to (Equation 5) to calculate the amount of image plane movement ΔPs due to the auxiliary lens 104 using (Equation 8). (Equation 8) ΔPs = Ks × ΔS

[0048] Next, the amount of movement ΔFf of the focus lens 105 at the infinity position when focusing at infinity is calculated using (Equation 9) obtained by applying the calculated amount of image plane movement ΔPs to (Equation 6). (Equation 9) ΔFf = ΔPs / Kff

[0049] Similarly, the movement amount ΔFn of the closest position of the focus lens 105 at the closest focus distance is calculated using (Equation 10) obtained by applying the image plane movement amount ΔPs to (Equation 7). (Equation 10) ΔFn = ΔPs / Kfn

[0050] Next, the process proceeds to step S508. In step S508, the drive range of the focus lens 105 is corrected using the movement amount ΔFf at the infinity position and the movement amount ΔFn at the closest position. The positions of the infinity and closest drive control ends of the focus lens 105 before correction are set to Lmf and Lmn, respectively. The stroke Ln of the focus lens is calculated using the following (Equation 11). (Equation 11) Ln = Lmn - Lmf (Lmf <Lmn)

[0051] Before the drive range is corrected, focus lens 105 drives within a range from Lmf to Lmn, as shown in FIG. 6(a). In this step, the drive range of focus lens 105 is corrected so that focus lens 105 can move through a stroke L' from Lmf-ΔFf to Lmn-ΔFn, as shown in FIG. 6(b). Note that even if the current rest position of focus lens 105 is outside the drive range newly set in step S508, it is preferable not to move focus lens 105 within the drive range unless a zoom operation or focus operation is input. This is because moving focus lens 105 changes the image magnification, which may result in an unintended change in image magnification by the user.

[0052] In this way, even if the auxiliary lens 104 moves unintentionally due to temperature changes or the like, it is possible to ensure a certain amount of margin from the infinity position to the control end on the infinity side, and a certain amount of margin from the close position to the control end on the close side, by resetting the drive range of the focus lens based on the amount of movement (deviation) of the auxiliary lens 104. As a result, it is possible to focus even on subjects at the infinity position or the closest distance, thereby achieving good focus operation.

[0053] When setting the driving range using a temperature sensor, it is difficult to take into account the variation in the amount of movement of the auxiliary lens 104 for each individual lens, as described above. If the position sensitivity of the auxiliary lens 104 is not high, the variation in the amount of image plane movement associated with the variation in the amount of movement is not large. Therefore, the driving range can be set based on the temperature detected by the temperature sensor after taking the variation into account. However, if the position sensitivity of the auxiliary lens 104 is high, the variation in the amount of image plane movement associated with the variation in the amount of movement becomes large. If the driving range is set taking into account the large variation, the variation in the margin between individuals with small and large temperature-related movement amounts will become large, resulting in individuals with an excessively large margin. In this embodiment, the driving range of the focus lens is set based on the amount of movement of the auxiliary lens 104, as described above, thereby alleviating this problem.

[0054] <Second embodiment> The second embodiment will be described below, but the same parts as those in the first embodiment will not be described. The difference from the first embodiment is the program executed by the microprocessor 118 to change the driving range of the focus lens 105, and therefore this program will be described in detail using the flowchart in FIG.

[0055] Steps S701 to S704 are the same as steps S501 to S504 in the first embodiment, and therefore their details will be omitted. First, in step S701, it is determined whether zoom driving is in progress. If it is not determined that zoom driving is in progress, the process ends. If it is determined that zoom driving is in progress, the process proceeds to step S702. In step S702, the stop position Ss of the auxiliary lens 104 during settling, which was saved in step S215, is acquired from the memory 120. In the following step S703, the current position Sc of the auxiliary lens 104 is acquired from the position detection sensor 116a. In the next step S704, the position difference ΔS of the auxiliary lens 104 is calculated using the above (Equation 4) from the stop position Ss of the auxiliary lens 104 during settling, acquired in steps S702 and S703, and the current position Sc of the auxiliary lens 104, and the process proceeds to step S705.

[0056] In step S705, the position difference ΔS, which is the positional deviation amount of the auxiliary lens 104 calculated in step S704, is compared with ΔSp+α, which is the sum of the position difference ΔSp of the auxiliary lens 104 stored in step S706 (described later) and a fixed value α. If ΔS is larger, the process proceeds to step S706, and if ΔS is equal to or smaller than ΔSp+α, the process ends.

[0057] In step S706, the position difference ΔS of the auxiliary lens 104 is stored as a stored position difference ΔSp. -Up to S710 The driving range of the focus lens 105 is of correction of Each time the drive range is changed, the position difference ΔSp is saved. That is, in step S705, it is determined whether the amount of positional deviation of the auxiliary lens 104 from the timing at which the position difference was calculated the previous time the drive range was changed to the timing at which the position difference is calculated this time is greater than a predetermined value α. The drive range is reset only if the amount of positional deviation from the timing at which the position difference was calculated the previous time the drive range was set is greater than the predetermined value α, and the set drive range is maintained if the amount of positional deviation is equal to or less than the predetermined value, which is different from the first embodiment. The saved position difference ΔSp is initialized to 0 during processing when the power is turned on.

[0058] Next, the process proceeds to step S707. Steps S707 to S710 are the same as steps S505 to S508 in the first embodiment, and therefore further details will be omitted. In step S707, the position sensitivity Ks of the auxiliary lens 104 is obtained from the memory 120. Next, in step S708, the infinity position sensitivity Kff and the close position sensitivity Kfn of the focus lens 105 are obtained from the memory 120. Next, in step S709, the correction amount of the drive control end of the focus lens 105 due to misalignment of the auxiliary lens 104 is determined. Based on the position difference ΔS obtained in step S704 and the sensitivity Ks obtained in step S707, the amount of image plane movement ΔPs caused by the auxiliary lens is calculated using the above (Equation 8). Then, the calculated ΔPs and the above (Equation 9) are used to calculate the amount of movement ΔFf of the focus lens 105 at the infinity position. Similarly, the movement amount ΔFn of the focus lens 105 at the closest position at the closest focus distance is calculated using the calculated image plane movement amount ΔPs and the above (Equation 10). Next, in step S710, the drive range of the focus lens 105 is changed using the movement amount ΔFf at the infinity position and the movement amount ΔFn at the closest position calculated in step S709.

[0059] As a result, even if the position of the auxiliary lens 104 moves due to temperature or the like after the zoom operation is stopped, the amount of movement (amount of deviation) is kept within the predetermined value α If it is greater than The drive range of the focus lens 105 is corrected. As a result, a certain amount of margin can be secured between the infinity position and the control end on the infinity side, and between the close position and the control end on the close side, to the extent that focus can be achieved at infinity or the closest distance even when the auxiliary lens 104 is moved, thereby achieving good focus operation. Also, unlike the first embodiment, the drive range of the focus lens is changed only when the amount of misalignment of the auxiliary lens exceeds a predetermined value α, which makes it possible to avoid a state in which the drive range constantly changes in a short cycle ΔT, thereby improving the stability of the drive range.

[0060] <Modification> Modifications of the first and second embodiments will now be described. In the above embodiments, the drive range was set based on the position difference ΔS between the position of the auxiliary lens detected during settling and the current position of the auxiliary lens. However, it is also possible to assume that the position of the auxiliary lens during settling should match the target position acquired in step S213, and use the amount of deviation between the target position and the current position of the auxiliary lens as the position difference ΔS, and set the drive range based on this amount of deviation.

[0061] In the above embodiment, the drive range of the focus lens (hereinafter referred to as the first range) is set in advance, and the control end of the first range is corrected based on the position difference ΔS of the auxiliary lens 104 to set the drive range of the focus lens 105 based on the amount of positional misalignment. However, the setting method is not limited to this. For example, when the absolute value of the position difference ΔS is equal to or less than a first value, the first range is set as the drive range of the focus lens. When the position difference ΔS is greater than the first value and equal to or less than a second value in the positive direction, a predetermined second range is set as the drive range of the focus lens. Furthermore, when the position difference ΔS is greater than the second value, a predetermined third range is set as the drive range of the focus lens. In this manner, the drive range of the focus lens may be set to predetermined ranges in stages. In this case, the relationship between the position difference ΔS of the auxiliary lens and the amount of movement of the image plane may be obtained in advance, the drive range may be set in advance based on this relationship, and data correlating each position difference ΔS with the range may be stored in memory 120. Similarly, in the negative direction, a predetermined range may be set as the drive range of the focus lens based on the magnitude of the position difference ΔS.

[0062] Furthermore, since the position between the infinity position and the closest position, whichever is closer to the control end (i.e., whichever has a smaller margin), is more susceptible to the influence of the amount of deviation, it is possible to set only the position of the control end which is closer in distance according to the amount of deviation of the auxiliary lens position.

[0063] In the first and second embodiments, a method for correcting the driving range of the focus lens was described to address the positional shift (occurrence of ΔS) of the auxiliary lens 104 due to temperature changes. However, in reality, the relationship between the position of the focus lens 105 and the corresponding in-focus object distance may shift due to the expansion and contraction of the lens barrel due to temperature changes. Therefore, a conventional method for correcting the shift in the relationship between the focus lens position and the object distance, such as that described in Japanese Patent No. 4857257, may be used in combination with the method described in the first and second embodiments. For example, a temperature sensor may be installed in the imaging device, and the driving range of the focus lens stored corresponding to the temperature may be read from memory 120 in accordance with the output of the temperature sensor. The read driving range of the focus lens is then corrected based on ΔS using the above method. This makes it possible to address both the positional shift of the auxiliary lens 104 due to temperature changes and the shift in the relationship between the position of the focus lens 105 and the in-focus object distance.

[0064] Furthermore, while the above embodiment has been described with respect to an image pickup device with an integrated lens, the present invention can also be applied to an image pickup device with an interchangeable lens. In this case, the processor that functions as the setting means for setting the drive range of the focus lens 105 may be provided on the interchangeable lens device side, or on the camera body side to which the interchangeable lens can be attached. If provided on the camera body side, the processor receives information such as information on the position and position sensitivity of each lens via communication means capable of communicating with the interchangeable lens device, and transmits information indicating the drive range to be set to the interchangeable lens side.

[0065] Although the present invention has been described in detail above based on preferred embodiments thereof, the present invention is not limited to these specific embodiments, and various forms within the scope of the gist of the present invention are also included in the present invention. Parts of the above-described embodiments may be combined as appropriate. [Explanation of symbols]

[0066] 102 Zoom Lens 104 Auxiliary Lens 105 focus lens 116a Position sensor 116b Position Scale 118 Microprocessors

Claims

1. A control device for an imaging optical system comprising a first variable magnification lens that moves with zooming, a second variable magnification lens whose position is controlled based on the position of the first variable magnification lens, and a focus lens that adjusts the focus position, a position detecting means for detecting the position of the second variable magnification lens; a setting means for setting a driving range of the focus lens based on the position of the second variable magnification lens; a position control unit for controlling the position of the focus lens, When the focus lens is stationary at a first position, A lens control device characterized in that, when the setting means changes the drive range of the focus lens from a third range including the first position to a fourth range excluding the first position, the position control means maintains the focus lens at the first position.

2. 2. The lens control device according to claim 1, wherein the setting means sets the driving range of the focus lens based on the amount of deviation between the position of the second variable magnification lens corresponding to the position of the first variable magnification lens and the position of the second variable magnification lens detected by the position detection means.

3. 3. The lens control device according to claim 2, wherein the setting means sets the driving range based on the amount of deviation, the position sensitivity of the second variable magnification lens, and the position sensitivity of the focus lens.

4. 4. The lens control device according to claim 2, wherein the setting means changes the position of the drive control end of the focus lens based on the amount of deviation.

5. The setting means If the deviation amount is equal to or less than a first predetermined value, a first range is set as a driving range of the focus lens; 5. The lens control device according to claim 2, wherein when the amount of deviation is greater than the first predetermined value, a second range different from the first range is set as the driving range of the focus lens.

6. The setting means 6. The lens control device according to claim 5, wherein when the amount of deviation is greater than the first predetermined value, the second range is calculated based on the amount of deviation, the position sensitivity of the second variable magnification lens, and the position sensitivity of the focus lens.

7. a storage means for storing information about the driving range; 6. The lens control device according to claim 5, wherein the first range and the second range are set in advance and stored in the storage means.

8. 8. The lens control device according to claim 2, wherein the setting means compares the amount of deviation with the amount of deviation acquired the previous time the driving range was set, and resets the driving range if the difference is greater than a predetermined value.

9. A lens control device as described in claim 1, characterized in that when the driving range of the focus lens is changed to the fourth range by the setting means while the focus lens is stationary at a first position, and after a zoom operation or focus operation is input, the position control means moves the focus lens within the driving range.

10. A lens control device described in any one of claims 1 to 6, characterized in that the position of the second variable magnification lens is controlled based on information representing the positional relationship between the first variable magnification lens and the second variable magnification lens that is pre-stored in memory.

11. The position of the second variable magnification lens corresponding to the position of the first variable magnification lens is 7. The lens control device according to claim 1, wherein a target position of the second variable magnification lens is determined based on the position of the first variable magnification lens.

12. A lens control device according to any one of claims 1 to 11; the imaging optical system; an imaging element that captures an image of a subject formed by the imaging optical system.

13. A lens control device according to any one of claims 1 to 11; a lens device comprising the imaging optical system;

14. An imaging device to which a lens device having an imaging optical system including a first variable magnification lens that moves with zooming, a second variable magnification lens whose position is controlled based on the position of the first variable magnification lens, and a focus lens that adjusts a focus position can be attached, A lens control device according to any one of claims 1 to 11; an imaging element for capturing an image of a subject formed by the imaging optical system; and a communication means for communicating with the lens device; The imaging device is characterized in that information indicating the driving range of the focus lens set by the setting means is transmitted to the lens device via the communication means.

15. A control method for an imaging optical system comprising a first variable magnification lens that moves with zooming, a second variable magnification lens whose position is controlled based on the position of the first variable magnification lens, and a focus lens that adjusts a focus position, comprising: a position detecting step of detecting the position of the second variable magnification lens; a setting step of setting a driving range of the focus lens based on the position of the second variable magnification lens; a position control step of controlling the position of the focus lens, When the focus lens is stationary at a first position, A control method characterized in that, when the setting process changes the driving range of the focus lens from a third range including the first position to a fourth range excluding the first position, the position control process maintains the focus lens at the first position.

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