Control device, operating device, driving device, and optical device

Abstract

To appropriately control a load acting on a movable member.SOLUTION: The control device includes a detection means 103 for detecting the position of the movable member 102, a generation means 110 for generating a load to be applied to the movable member, and a control means 104 for performing control to change the load generated by the generation means according to the position of the movable member.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a control device for controlling a load acting on a movable member. [Background technology]

[0002] In an imaging system, an operating device (demand) and a driving device (drive unit) are used that have operating members that are operated by a user to instruct a lens device to perform operations such as zooming and focusing. Some of these devices are connected to a load generating device that applies a load to the operating member in order to obtain a good operating feel for the operating member. Patent Document 1 discloses a device in which a magnetorheological fluid (MRF) device containing an MRF is connected to an operating member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-93022 Summary of the Invention [Problem to be solved by the invention]

[0004] However, depending on the configuration of the mechanism that connects the operating member and the load generating device in the operating device or the drive unit, the load acting on the operating member during operation may fluctuate, resulting in a loss of a good operating feel for the operating member. [Means for solving the problem]

[0005] A control device according to one aspect of the present invention is characterized by having a detection means for detecting the position of a movable member, a generation means for generating a load to be applied to the movable member, and a control means for performing load control to change the load generated by the generation means in accordance with the position of the movable member. Note that an operating device, a drive device, and an optical device using the above control device also constitute another aspect of the present invention. [Effects of the Invention]

[0006] According to the present invention, the load acting on the movable member can be appropriately controlled. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram showing the configuration of an optical device according to a first embodiment. [Figure 2] 3 is a flowchart showing a process in the first embodiment. [Figure 3] 4 is a diagram showing the relationship (load information) between the applied voltage and the generated torque of the load generating device in the first embodiment. FIG. [Figure 4] FIG. 10 is a diagram showing the characteristics of the magnetorheological fluid in Example 2. [Figure 5] 10 is a flowchart showing a process in the second embodiment. [Figure 6] FIG. 10 is a diagram showing the relationship between the applied voltage and the generated torque of the load generating device in the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. [Example]

[0009] 1 shows the configuration of an imaging system including a lens apparatus 100 as an optical apparatus according to a first embodiment and an imaging apparatus 200 to which the lens apparatus 100 is detachably attached. The lens apparatus 100 operates by receiving power supply from the imaging apparatus 200.

[0010] The lens device 100 has an imaging optical system including a focus lens group 101. The focus lens group 101 moves in the optical axis direction to perform focusing. A focus ring 102 as a movable member is an operating member that is rotated by a user to instruct the focus lens group 101 to be driven. The focus ring 102 has a limited rotation range (movable range), and there is a one-to-one correspondence between the rotational position of the focus ring 102 within the rotation range and the position of the focus lens group 101 in the optical axis direction.

[0011] The position detection unit 103, which serves as a detection means, detects the rotational position (rotation angle) of the focus ring 102 and outputs a position signal corresponding to the detected rotational position. The position detection unit 103 is configured, for example, by an encoder having a light-emitting unit, a light-receiving unit, and a reflective scale, and outputting two-phase analog signals that are 90° out of phase with each other. The analog position signal output from the position detection unit 103 is input to the lens CPU 104, which serves as a control means. The lens CPU 104 performs A / D conversion on the input analog position signal and performs calculations on the generated digital position signal to generate a focus command signal for the focus drive circuit 108. The focus drive circuit 108 drives a focus motor (drive means) 106, which is configured, for example, by a DC motor or a stepping motor, in response to the focus command signal. The drive force of the focus motor 106 drives the focus lens group 101 in the optical axis direction.

[0012] The focus clutch 105 can be switched between a first state (servo drive state) in which the driving force of the focus motor 106 can be transmitted to the focus ring 102 and a second state (manual drive state) in which the driving force cannot be transmitted, in response to the operation of a switch 107. In the servo drive state, the focus lens group 101 is driven and the focus ring 102 is rotated by the drive of the focus motor 106. In the manual drive state, the rotational operating force of the focus ring 102 is transmitted to the focus lens group 101 via a focus mechanism (not shown), so that the focus lens group 101 can be driven in the optical axis direction without relying on the focus motor 106. The state of the switch 107, which corresponds to the state of the focus clutch 105, is input to the lens CPU 104.

[0013] The load driving circuit 109 is composed of an H-bridge motor driver IC, etc., and changes the voltage applied to the load generating device 110 as a generating means using a control method such as pulse width modulation (PWM) in response to a load command signal from the lens CPU 104.

[0014] The load generating device 110 is a device that uses a magnetorheological fluid (MRF), whose viscosity changes as a magnetic field changes in response to an applied voltage, and is capable of generating a load (torque) according to the viscosity. The load generating device 110 is mechanically connected to the focus ring 102 via a load mechanism 115, and the load generated by the load generating device 110 acts on the focus ring 102 via the load mechanism 115. The load mechanism 115 includes not only a mechanism that transmits the load of the load generating device 110 to the focus ring 102 but also a biasing mechanism that presses the focus ring 102 against the housing of the lens apparatus 100 to prevent the focus ring 102 from rotating freely. The load mechanism 115 includes components, such as the biasing mechanism, that cause fluctuations in the load acting on the focus ring 102. For example, when the load mechanism 115 transmits torque via a gear train, the torque increases at meshing points with small backlash and decreases at meshing points with large backlash.

[0015] In this embodiment, the load generating device 110 generates a load according to an applied voltage, but the load generating device 110 may generate a load according to an applied current. In this case, the applied current is controlled instead of the applied voltage, which will be described later.

[0016] The load setting circuit 111 is composed of a variable resistor, rotary switch, etc. that can be operated by the user, and is provided so that the user can set the magnitude of the load generated by the load generating device 110 (i.e., the voltage applied to the load generating device 110). A setting signal from the load setting circuit 111 is input to the lens CPU 104, and the lens CPU 104 causes the load driving circuit 109 to set the voltage applied to the load generating device 110 in accordance with the setting signal. Note that the load setting circuit 111 may transmit the setting signal via communication with the lens CPU 104. Furthermore, the voltage applied to the load generating device 110 may be changed in accordance with the magnitude of the power supplied from the imaging apparatus 200 to the lens apparatus 100.

[0017] Storage unit 112 is configured with a nonvolatile memory and stores, as load information, information related to the load acting on focus ring 102 that varies depending on the rotational position of focus ring 102, as information used for load correction control (load control) described below. Details of the load information will be described later. Load drive circuit 109, load generation device 110, load setting circuit 111, storage unit 112, and lens CPU 104 configure a control device.

[0018] The communication circuit 113 is a circuit for communicating with an external device, in this case, the image capturing device 200 external to the lens device 100. The lens CPU 104 as a computer controls the focus motor 106 and controls communication with the image capturing device 200 via the communication circuit 113 in accordance with software (programs). The external device is not limited to the image capturing device, but may also be an image processing device or a personal computer that processes or uses image data generated by the image capturing device 200.

[0019] The imaging device 200 has an imaging element 201 such as a CCD sensor or a CMOS sensor. The imaging element 201 photoelectrically converts (captures) an optical image formed by the imaging optical system of the lens device 100. The video signal generation unit 203 generates an image signal based on the imaging signal output from the imaging element 201.

[0020] The viewfinder 202 displays images, information related to focus operations, etc. The display processing unit 204 generates images to be displayed on the viewfinder 202 in accordance with an image signal from the video signal generation unit 203 and drawing information (described later) from the camera CPU 205. The camera CPU 205 generates and synthesizes drawing information (computer graphics, etc.) based on information acquired from the lens device 100 via the communication circuit 206 in accordance with software (programs).

[0021] 2 shows a process (control method) performed by the lens CPU 104 in the lens device 100. The lens CPU 104 executes this process at a predetermined cycle (for example, 1 KHz) based on the time measured by an internal timer.

[0022] In step S101, the lens CPU 104 performs A / D conversion on the analog position signal output from the position detection unit 103.

[0023] Next, in step S102, the lens CPU 104 performs calculations on the digital position signal obtained by A / D conversion to obtain position information within the rotation range of the focus ring 102.

[0024] In step S103, the lens CPU 104 determines whether the state of the switch 107 is the servo drive state or the manual drive state. If it is the servo drive state, the lens CPU 104 performs the process of step S104, and if it is the manual drive state, the lens CPU 104 performs the process of step S106.

[0025] In step S104, the lens CPU 104 generates a focus command signal so that the current position indicated by the position information acquired in step S102 coincides with the target position of the focus lens group 101 instructed by the imaging device 200 or an external device (not shown).

[0026] Then, in step S105, the lens CPU 104 outputs the generated focus command signal to the focus drive circuit 108. Note that the lens CPU 104 may repeatedly generate the focus command signal so as to perform feedback control until the current position of the focus lens group 101 coincides with the target position.

[0027] In step S106, the lens CPU 104 reads out the current voltage applied to the load generating device 110. Then, the lens CPU 104 refers to a lookup table stored in advance for the read-out applied voltage to acquire the current load setting value, which is a value in five stages from 0 to 4, for example.

[0028] Next, in step S107, the lens CPU 104 calculates the applied voltage from the current load setting value acquired in step S106, the current position information of the focus ring 102, and the load information stored in the storage unit 112. The calculation of the applied voltage will be described in detail later.

[0029] Furthermore, in step S108, the lens CPU 104 outputs information about the applied voltage calculated in step S107 to the load driving circuit 109, and causes the load driving circuit 109 to apply that voltage to the load generating device 110. In other words, load correction control is performed.

[0030] 3(a) and (b) show the relationship between the position information of the focus ring 102, the voltage applied to the load generating device 110, and the load (torque) generated by the load generating device 110 for each applied voltage. Fig. 3(a) shows the case where the applied voltage is fixed, and Fig. 3(b) shows the case where the applied voltage is corrected by performing load correction control.

[0031] 3(a), when the applied voltage is fixed, the load acting on focus ring 102 varies depending on the rotational position of focus ring 102 due to the characteristics of load generating device 110 and the configuration of load mechanism 115, which are factors that cause the load to fluctuate as described above. The magnitude of the load fluctuation increases as the applied voltage increases. In this embodiment, to minimize such load fluctuations, load correction control is performed to change the load generated by load generating device 110 depending on the rotational position of focus ring 102.

[0032] The load correction control uses the load information described above. As shown in FIG. 3A, the load information includes position information for rotational position 301 where the load (torque) of focus ring 102 is greater than at other rotational positions, and information on the torque (second load) at rotational position 301. The load information also stores position information for rotational position 302 where the torque starts to increase toward the torque at rotational position 301, and information on the torque (first load) at rotational position 302. The load information also stores position information for rotational position 303 where the torque stops decreasing from the torque at rotational position 301 (the torque returns to its original value), and information on the torque (first load) at rotational position 303. Note that the load information may also be information indicating the difference in torque between rotational position 301 and rotational positions 302 and 303.

[0033] Then, the lens CPU 104 calculates (corrects) the voltage to be applied to the load generating device 110 so that the torque in the section from rotational position 302 to rotational position 301 approaches the torque at rotational position 302 (preferably becomes the same as the torque at rotational position 302). Similarly, the lens CPU 104 corrects the voltage to be applied to the load generating device 110 so that the torque in the section from rotational position 301 to rotational position 303 approaches the torque at rotational position 303 (preferably becomes the same as the torque at rotational position 303).

[0034] As a result, as shown in FIG. 3(b), the increase in torque at rotational position 301 shown in FIG. 3(a) is suppressed, and torque fluctuations at all rotational positions are suppressed to a small level.

[0035] According to this embodiment, the voltage applied to load generating device 110, i.e., the magnitude of the load generated by load generating device 110, is controlled in accordance with the rotational position of focus ring 102, thereby suppressing fluctuations in the load acting on focus ring 102. This prevents the operational feel of focus ring 102 from being impaired.

[0036] In addition, the lens CPU 104 may control the magnitude of the load generated by the load generating device 110 so that the load that varies depending on the rotational position of the focus ring 102 falls within a predetermined range (for example, the second load is within 5% of the first load). [Example]

[0037] Next, an optical device according to a second embodiment will be described. Fig. 4 shows the relationship (MRF characteristics) between the voltage applied to the load generating device 110 and the torque generated by the MRF in the load generating device 110 in the second embodiment. A curve 401 shows the relationship between the applied voltage and the torque when the voltage applied to the load generating device 110 is increased from a low voltage. A curve 402 shows the relationship between the applied voltage and the torque when the voltage applied to the load generating device 110 is decreased from a high voltage.

[0038] Due to the influence of residual magnetism, the viscosity of the MRF changes differently when the applied voltage is increased from a low voltage and when it is decreased from a high voltage, resulting in hysteresis in the MRF characteristics in both cases. Specifically, when the applied voltage is increased from a low voltage, the torque increases almost linearly with increasing applied voltage, as shown by curve 401. On the other hand, when the applied voltage is decreased from a high voltage, the linearity of the torque change with decreasing applied voltage decreases due to the influence of residual magnetism, as shown by curve 402, and the torque increases even at low applied voltages.

[0039] The flowchart in FIG. 5 shows the processing performed by the lens CPU 104 in this embodiment.

[0040] The processing from step S201 to step S205 is the same as the processing from step S101 to step S105 in the first embodiment (FIG. 2).

[0041] If the lens CPU 104 determines in step S203 that the switch 107 is in the manual drive state, it proceeds to step S206. In step S206, it determines whether a demagnetization flag or a magnetization flag, which will be described later, is set. If it is set, it proceeds to step S207, and if it is not set, it proceeds to step S209.

[0042] In step S207, the lens CPU 104 determines whether a predetermined time (here, 3 ms) has elapsed since the demagnetization flag or the magnetization flag was set. If the predetermined time has elapsed, the lens CPU 104 performs the process of step S208; if the predetermined time has not elapsed, the lens CPU 104 ends this process.

[0043] In step S208, the lens CPU 104 determines that the demagnetization or magnetization of the MRF has been completed after the lapse of a predetermined time, and clears the demagnetization flag and the magnetization flag, and then ends this process.

[0044] In step S209, lens CPU 104 acquires optical sensitivity, which indicates the amount of change in the optical state per unit rotational operation amount of focus ring 102, from the position information of focus ring 102 acquired in step S202 and information indicating the optical characteristics of the imaging optical system associated with the position information. The higher the optical sensitivity, the greater the amount of change in the optical state per unit rotational operation amount of focus ring 102. The amount of change in the optical state is, for example, the amount of movement of the image plane due to movement of focus lens group 102 or the amount of change in the focal position on the image plane.

[0045] Next, in step S210, the lens CPU 104 reads out the current voltage applied to the load generating device 110. Then, the lens CPU 104 refers to a lookup table stored in advance for the read-out applied voltage to acquire the current load setting value, which is a value in five stages, for example, from 0 to 4.

[0046] Next, in step S211, the lens CPU 104 determines whether the load setting value acquired in step S210 has been changed from the load setting value acquired in the previous routine. If the load setting value has been changed, the lens CPU 104 performs the process of step S212; if it has not been changed, the lens CPU 104 performs the process of step S218.

[0047] In step S212, the lens CPU 104 determines whether the optical sensitivity acquired in step S209 is equal to or greater than a predetermined value. If it is equal to or greater than the predetermined value, the lens CPU 104 performs the process of step S213, and if it is less than the predetermined value, the lens CPU 104 performs the process of step S214.

[0048] In step S213, the lens CPU 104 sets the demagnetization flag, and then performs the process of step S215.

[0049] On the other hand, in step S214, the lens CPU 104 sets the magnetization flag, and then performs the process of step S215.

[0050] In step S215, the lens CPU 104 determines the flag state, i.e., whether the demagnetization flag or the magnetization flag is set. If the demagnetization flag is set, the lens CPU 104 performs the process of step S216, and if the magnetization flag is set, the lens CPU 104 performs the process of step S217.

[0051] In step S216, the lens CPU 104 sets the voltage applied to the load generating device 110 to the minimum value, thereby demagnetizing the MRF, and then performs the process of step S219.

[0052] In step S217, the lens CPU 104 sets the voltage applied to the load generating device 110 to the maximum value, thereby magnetizing the MRF, and then performs the process of step S219.

[0053] In step S218, the lens CPU 104 calculates the applied voltage from the current load setting value acquired in step S211, the current position information of the focus ring 102, and the load information stored in the storage unit 112. The calculation of the applied voltage will be described in detail later. The lens CPU 104 then performs the process of step S219.

[0054] In step S219, the lens CPU 104 outputs information about the applied voltage (target voltage) set or calculated in step S216, S217, or S218 to the load driving circuit 109, and causes the load driving circuit 109 to apply a voltage corresponding to the target voltage to the load generating device 110. In other words, load correction control is performed.

[0055] The calculation of the applied voltage in step S218 will be described with reference to FIG. 6. First, the lens CPU 104 determines, from the currently applied voltage, whether the MRF is in a demagnetized state, a magnetized state, or neither. If the applied voltage is at its minimum value, the MRF is in a demagnetized state. The relationship between the applied voltage and torque at this time is shown by curve 401. On the other hand, if the applied voltage is at its maximum value, the MRF is in a magnetized state. The relationship between the applied voltage and torque at this time is shown by curve 402. If the MRF is neither demagnetized nor magnetized, the MRF remains in the same state as the previous time.

[0056] Torque 601 in the figure indicates the torque calculated from the load setting value acquired in step S211. In the demagnetized state, voltage 602 corresponding to torque 601 is used as the reference voltage, and in the magnetized state, voltage 603 corresponding to torque 601 is used as the reference voltage.

[0057] Then, lens CPU 104 calculates the voltage to be applied to load generating device 110 using the information on the MRF characteristics shown in FIG. 4 (FIG. 6), information on the reference voltage, position information on focus ring 102, and the load information shown in FIG. 3(a). For example, let the torque after voltage correction at rotational position 301 in FIG. 3(a) be 604. In this case, if the reference voltage is voltage 602, the applied voltage is calculated by decreasing it by A as shown in FIG. 6. Also, if the reference voltage is voltage 603, the applied voltage is calculated by decreasing it by B.

[0058] According to this embodiment, the voltage applied to load generating device 110, which has hysteresis in its MRF characteristics, is controlled in accordance with the rotational position of focus ring 102. In other words, the magnitude of the load generated by load generating device 110 is controlled. This makes it possible to suppress fluctuations in the load acting on focus ring 102. This makes it possible to avoid loss of the operational feel of focus ring 102.

[0059] Furthermore, in this embodiment, when the optical sensitivity is high, the voltage applied to the load generating device 110 is lowered to demagnetize the MRF, and then the voltage is set (raised) to a target voltage that will obtain the target torque. This allows for accurate torque setting. On the other hand, when the optical sensitivity is low, the voltage applied to the load generating device 110 is increased to magnetize the MRF, and then the voltage is set (raised) to a target voltage. This allows for torque setting with reduced power consumption.

[0060] Similarly, when controlling the current applied to the load generating device 110, the applied current may be lowered to demagnetize the MRF or increased to magnetize the MRF, and then set to a target current that will obtain the target torque.

[0061] In the above embodiments, the lens device 100 having the focus ring 102, which is a movable member (operation member), is described as having a control device, but the control device can also be included in devices other than the lens device. For example, the control device may be included in an external operation device such as a demand that can be connected to the lens device and has an operation member equivalent to a focus ring, or an external drive device such as a drive unit that has an operation member and a lens drive mechanism (drive means) and is attached to the lens device.

[0062] In the above embodiments, the case where the voltage applied to the load generating device that uses an MRF to generate a load acting on an operation member (focus ring 102) as a movable member has been described. However, the movable member is not limited to the operation member, and the load generating device is not limited to one that uses an MRF. For example, an optical element such as a lens that moves within a lens device may be used as the movable member, and the voltage applied to a DC motor that serves as a load generating device that generates a load due to the movement of the optical element (such as a fall due to gravity) may be controlled.

[0063] The above embodiment includes the following configurations.

[0064] (Configuration 1) a detection means for detecting the position of the movable member; a generating means for generating a load to be applied to the movable member; and a control means for controlling the load generated by the generating means to be changed in accordance with the position of the movable member. (Configuration 2) 2. The control device according to configuration 1, wherein the control means performs the control so as to reduce fluctuations in the load acting on the movable member depending on the position of the movable member. (Configuration 3) 3. The control device according to configuration 1 or 2, wherein the control means performs the control so that the load acting on the movable member, which varies depending on the position of the movable member, falls within a predetermined range. (Configuration 4) 4. The control device according to any one of configurations 1 to 3, wherein the control means performs the control using information about the load acting on the movable member, which varies depending on the position of the movable member. (Configuration 5) 5. The control device according to any one of configurations 1 to 4, further comprising a mechanism that causes the load acting on the movable member to fluctuate depending on the position of the movable member. (Configuration 6) 6. The control device according to any one of configurations 1 to 5, wherein the generating means generates the load using a magnetorheological fluid. (Configuration 7) the generating means generates the load having a magnitude corresponding to an applied voltage or an applied current; 7. The control device according to any one of configurations 1 to 6, wherein the control means performs the control by changing the applied voltage or the applied current depending on the position of the movable member. (Configuration 8) 8. The control device according to configuration 7, wherein the control means performs control such that the applied voltage or the applied current is first lowered and then raised to a target voltage or target current. (Configuration 9) The optical state of the optical device changes depending on the position of the movable member, 9. The control device according to configuration 8, wherein the control means performs the control when the sensitivity of the change in the optical state to the change in the position of the movable member is equal to or greater than a predetermined value. (Configuration 10) 8. The control device according to configuration 7, wherein the control means performs the control by increasing the applied voltage or the applied current and then decreasing it to a target voltage or target current. (Configuration 11) A control device according to any one of configurations 1 to 10; an operating member operable by a user as the movable member; (Configuration 12) 11. A drive device comprising: the control device according to any one of configurations 1 to 10; an operating member as the movable member; and an optical element that is movable in response to operation of the operating member. (Configuration 13) A control device according to any one of claims 1 to 10; an operating member as the movable member; and an optical element that is movable in response to operation of the operating member.

[0065] (Other Examples) The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program.The present invention can also be realized by a circuit (e.g., ASIC) that realizes one or more functions.

[0066] The embodiments described above are merely representative examples, and various modifications and alterations are possible to each embodiment when implementing the present invention. [Explanation of symbols]

[0067] 100 Lens device 102 Focus ring 104 Lens CPU 103 Position detection unit 110 Load Generation Device

Claims

1. a detection means for detecting the position of the movable member; a generating means for generating a load to be applied to the movable member; and a control means for controlling the load generated by the generating means to be changed in accordance with the position of the movable member.

2. 2. The control device according to claim 1, wherein the control means performs the control so as to reduce fluctuations in the load acting on the movable member depending on the position of the movable member.

3. 2. The control device according to claim 1, wherein the control means performs the control so that the load acting on the movable member, which varies depending on the position of the movable member, falls within a predetermined range.

4. 2. The control device according to claim 1, wherein the control means performs the control using information about the load acting on the movable member, which varies depending on the position of the movable member.

5. 2. The control device according to claim 1, further comprising a mechanism that causes the load acting on the movable member to fluctuate depending on the position of the movable member.

6. 2. The control device according to claim 1, wherein the generating means generates the load using a magnetorheological fluid.

7. the generating means generates the load having a magnitude corresponding to an applied voltage or an applied current; 2. The control device according to claim 1, wherein the control means performs the control by varying the applied voltage or the applied current in accordance with the position of the movable member.

8. 8. The control device according to claim 7, wherein the control means performs the control by lowering the applied voltage or the applied current and then raising it to a target voltage or target current.

9. The optical state of the optical device changes depending on the position of the movable member, 9. The control device according to claim 8, wherein the control means performs the control when the sensitivity of the change in the optical state to the change in the position of the movable member is equal to or greater than a predetermined value.

10. 8. The control device according to claim 7, wherein the control means performs the control by increasing the applied voltage or the applied current and then decreasing it to a target voltage or target current.

11. A control device according to any one of claims 1 to 10; an operating member operable by a user as the movable member;

12. A control device according to any one of claims 1 to 10; an operating member as the movable member; and a driving means for driving an optical element provided in the optical device.

13. A control device according to any one of claims 1 to 10; an operating member as the movable member; and an optical element that is movable in response to operation of the operating member.

14. A method for controlling a device that generates a load to be applied to a movable member, comprising: detecting the position of the movable member; and performing control to change the load generated by the device in accordance with the position of the movable member.

15. A program causing a computer to execute a process according to the control method of claim 14.

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