Zoom lens actuator control device, and zoom camera using the same

Abstract

A zoom lens actuator control device according to an embodiment of the present application includes a command sensing section for sensing a position command to move a lens unit stopped at a position on a guide rail to a target position on the guide rail, and a control switching section for, after the position command is sensed by the command sensing section, delivering an initial control signal of the first control section to the zoom lens actuator until a predetermined control switching time point arrives, and when the control switching time point arrives, delivering a subsequent control signal of the second control section to the zoom lens actuator instead of the initial control signal of the first control section.

Description

Technical Field

[0001] The present invention relates to a zoom lens actuator control device and a zoom camera using the same, and more specifically, to a zoom lens actuator control device that changes the zoom magnification by controlling a zoom lens actuator for moving a lens unit of a zoom lens along a guide rail arranged inside the zoom lens, and a zoom camera using the same. Background Technology

[0002] Generally, a zoom camera is a camera configured to magnify or reduce the size of an image of a target object by using a zoom lens capable of changing the focal length. The zoom lens used in such a zoom camera includes a zoom lens actuator that adjusts the distance between lens elements by moving the lens elements of the zoom lens along guide rails arranged inside the zoom lens in front of or behind the zoom lens.

[0003] However, existing PID control technology, which combines proportional control, proportional-integral control, and proportional-derivative control to control zoom lens actuators, suffers from a response delay problem. Even when the zoom lens actuator is driven by user operation to generate driving force, the lens unit, which is stationary on the guide rail, cannot move immediately until the driving force of the zoom lens actuator is sufficiently increased by proportional-integral control.

[0004] Furthermore, existing PID control technology applies excessive driving force to the lens unit in order to overcome the static friction of the lens unit. This causes the lens unit to move rapidly at the moment when the static friction of the lens unit is converted into dynamic friction due to the movement of the lens unit, resulting in an overshoot problem.

[0005] Furthermore, as disclosed in Srinivasan Arumugam's "ASIMPLE METHOD FOR COMPENSATINGSTICTION NONLINEARITY IN OSCILLATING CONTROL LOOPS" (JFET Vol 6, No 4, Aug-Sep 2014, pp. 1846-1855), the conventional technique addresses the response delay caused by the static friction of the driven target by adding a knocking signal to the control signal used to control the drive device, thereby preventing the driven target from remaining stationary. However, when this technique is applied to the control of zoom lens actuators, there is a problem of excessive vibration caused by the knocking signal added to the control signal. Summary of the Invention

[0006] Technical issues

[0007] The technical problem to be solved by the present invention is to provide a zoom lens actuator control device and a zoom camera using the same, which prevents response delay caused by static friction of the lens unit, minimizes overshoot caused by excessive driving force, and reduces vibration generated during operation of the zoom lens actuator.

[0008] Solution to the problem

[0009] According to an embodiment of the present invention, a zoom lens actuator control device is a means of changing the zoom magnification of a zoom lens by controlling a zoom lens actuator for moving a lens unit of a zoom lens along a guide rail arranged inside the zoom lens. The device includes: a command sensing unit for sensing a position command to move a lens unit stopped at a position on the guide rail towards a target position on the guide rail; a first control unit for generating an initial control signal such that the zoom lens actuator generates a predetermined initial driving force required to move the lens unit towards the target position; and a second control unit for generating subsequent control signals to perform PID (Proportional Integral Derivative) control of the zoom lens actuator. The control unit, which senses the position command by the command sensing unit, transmits the initial control signal of the first control unit to the zoom lens actuator before the predetermined control switching time point arrives. When the control switching time point arrives, it transmits the subsequent control signal of the second control unit to the zoom lens actuator to replace the initial control signal of the first control unit.

[0010] In one embodiment, the first control unit includes: an initial driving force calculation module, which calculates the initial driving force by considering the movement direction of the lens unit according to the position command, the maximum static friction force of the lens unit, and the external forces acting on the lens unit by the tilt of the guide rail and gravity; and a control signal generation module, which generates an initial control signal corresponding to the calculated initial driving force.

[0011] In one embodiment, the first control unit further includes a friction information providing module. The friction information providing module refers to a friction information table on the guide rail that records the maximum static friction of the lens unit according to the moving direction and position, and provides the initial driving force calculation module with maximum static friction information corresponding to the moving direction of the lens unit according to the position command and the current position of the lens unit.

[0012] In one embodiment, the first control unit further includes an external force information providing module, which acquires external force information through a sensor for sensing the posture or tilt of the guide rail, and provides the acquired external force information to the initial driving force calculation module.

[0013] In one embodiment, the second control unit refers to the initial control signal transmitted to the zoom lens actuator before the control switching time point arrives, and generates a subsequent control signal so that the zoom lens actuator generates a subsequent driving force at the time of the control switching time point that is within a predetermined value of the difference between the initial driving force and the initial driving force.

[0014] In one embodiment, a switching time notification unit is further included. When the command sensing unit senses the location command, the switching time notification unit measures the time elapsed after the location command is sensed, and when the measured time reaches a predetermined reference time, it notifies the control switching unit that the control switching time has arrived.

[0015] According to an embodiment of the present invention, a zoom camera is configured to change the zoom magnification of a zoom lens using a zoom lens actuator control device according to the above embodiment.

[0016] According to an embodiment of the present invention, it can be implemented using a computer program, which is recorded in a recording medium as a computer program that performs the above-mentioned actions.

[0017] Invention Effects

[0018] According to the present invention, when a position command is detected to move a lens unit stopped at one position on the guide rail to a target position on the guide rail, the first control unit performs initial control to generate a predetermined initial driving force in the zoom lens actuator, so that the corresponding lens unit can move towards the target location without delay. When the lens unit starts to move, the second control unit performs PID control on the zoom lens actuator until the lens unit is placed at the target position according to the position command. Thus, response delay caused by static friction of the lens unit can be prevented while overshoot caused by excessive driving force can be minimized.

[0019] Furthermore, since the first control unit controls the zoom lens actuator without any additional signals that cause vibration (such as a knock signal), the vibration generated during the operation of the zoom lens actuator can be reduced.

[0020] Furthermore, the first control unit does not use a complex calculation model, but instead uses a relatively simple calculation formula that takes into account the maximum static friction of the lens unit and the external force acting on the lens unit to calculate the initial driving force of the zoom lens actuator, thereby simplifying the zoom magnification adjustment system of the zoom camera and reducing manufacturing costs.

[0021] Furthermore, it will be clearly understood from the following description that any technical problem not mentioned in the various embodiments of the present invention can be solved by those skilled in the art. Attached Figure Description

[0022] Figure 1 This is a block diagram illustrating a zoom ratio adjustment system for a zoom camera according to an embodiment of the present invention.

[0023] Figure 2 This is a diagram showing an example of a zoom lens used in a zoom camera.

[0024] Figure 3 This is a diagram illustrating a zoom lens actuator control device according to an embodiment of the present invention.

[0025] Figure 4 This is a diagram showing the forces acting on the lens unit located on the guide rail.

[0026] Figure 5 This is a diagram showing the first control unit of a zoom lens actuator control device according to an embodiment of the present invention.

[0027] Figure 6 This is a graph showing the starting current of the lens unit based on its position.

[0028] Figure 7 This is a graph comparing the control results of the zoom lens actuator of the present invention with those of existing PID control methods. Detailed Implementation

[0029] Best way to carry out the invention

[0030] A zoom lens actuator control device according to an embodiment of the present invention is a device for changing the zoom magnification of a zoom lens by controlling a zoom lens actuator for moving a lens unit of the zoom lens along a guide rail arranged inside the zoom lens. The device includes: a command sensing unit for sensing a position command to move a lens unit stopped at a position on the guide rail to a target position on the guide rail; a first control unit for generating an initial control signal that causes the zoom lens actuator to generate a predetermined initial driving force required to move the lens unit to the target position; and a second control unit for generating subsequent control signals to perform PID (Proportional Integral Derivative) control of the zoom lens actuator. The control unit, after the command sensing unit senses the position command, transmits the initial control signal of the first control unit to the zoom lens actuator before the predetermined control switching time point arrives. When the control switching time point arrives, it transmits the subsequent control signal of the second control unit to the zoom lens actuator to replace the initial control signal of the first control unit.

[0031] Methods of implementing the present invention

[0032] To clarify the technical problem to be solved by the present invention, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, if the description of related prior art would obscure the main idea of ​​the present invention, such description will be omitted. Furthermore, the terminology used in this specification is defined with consideration of its function in the present invention, and these terms may be changed according to the designer's, manufacturer's, or customary practice. Therefore, the definitions of the terms described below should be determined based on the entire content of this specification.

[0033] Figure 1 This is a block diagram of a zoom ratio adjustment system for a zoom camera according to an embodiment of the present invention.

[0034] like Figure 1 As shown, a zoom ratio adjustment system for a zoom camera 2 according to an embodiment of the present invention includes: a zoom ratio operation unit 10, a zoom lens 20, a zoom lens actuator 30, a posture sensing sensor 40 and a Hall sensor 50, and also includes a zoom lens actuator control device 100 according to the present invention.

[0035] The zoom ratio operation unit 10 is configured to generate a position command for changing the position of the lens unit arranged inside the zoom lens 20 based on the user's operation of changing the zoom ratio. For this purpose, the zoom ratio operation unit 10 may include an input device such as a dial, button, or touchscreen for adjusting the zoom ratio.

[0036] The zoom lens 20 is configured to change the focal length while maintaining the focus or aperture value of the image to be captured. As described later, the zoom lens 20 may include lens units and guide rails for guiding the movement of the lens units. Each lens unit may include a lens module consisting of at least one convex lens, at least one concave lens, or a combination thereof, and a lens holder that movably attaches the lens module to the guide rail.

[0037] The zoom lens actuator 30 is configured as a lens unit that moves the zoom lens 20 along a guide rail arranged inside the zoom lens 20. For this purpose, the zoom lens actuator 30 may include a drive device for generating driving force. For example, the zoom lens actuator 30 may include a voice coil motor (VCM). Since VCMs have characteristics such as fast response speed and low noise, the operating performance and quality of the zoom lens actuator 30 can be improved.

[0038] The attitude sensing sensor 40 is configured to sense the attitude or tilt of a guide rail arranged inside the zoom camera 2 or zoom lens 20. For this purpose, the attitude sensing sensor 40 may include an acceleration sensor or a gyroscope sensor.

[0039] The Hall sensor 50 is configured to measure the current position of the lens unit moving along a guide rail arranged inside the zoom lens 20 and feed it back to the zoom lens actuator control device 100.

[0040] According to the zoom lens actuator control device 100 of the present invention, the zoom magnification of the zoom lens 20 is changed by user operation control of the zoom lens actuator 30 in the zoom magnification adjustment system of the zoom camera 2 described above. For this purpose, the zoom lens actuator control device 100 refers to the target position x* of the lens unit based on the position command generated by the zoom magnification operation unit 10, the current position x of the lens unit sensed by the Hall sensor 50, and the posture or tilt of the zoom camera 2 or the zoom lens 20 sensed by the posture sensing sensor 40, to cause the zoom lens actuator 30 to generate a control signal u that produces a driving force with a predetermined direction and magnitude.

[0041] The zoom lens actuator control device 100 can be implemented by a combination of hardware such as a memory and a processor and a computer program executed by the hardware.

[0042] Figure 2 An example of a zoom lens 20 applied to a zoom camera 2 is shown.

[0043] like Figure 2 As shown, the zoom lens 20 is configured to change the focal length while maintaining the focus or aperture value of the image to be captured. For this purpose, the zoom lens 20 may include lens units 24, 26a, 26b, and a guide rail 28 for guiding the movement of the lens units 26a, 26b within the frame 22 constituting the support structure. Each lens unit may include a lens module consisting of at least one convex lens, at least one concave lens, or a combination of both, and a lens holder that movably connects the lens module to the guide rail 28.

[0044] The zoom lens actuator 30 is configured to move lens units 26a, 26b forward or backward along a guide rail 28 arranged inside the zoom lens 20 to change the focal length of the zoom lens 20. For this purpose, the zoom lens actuator 30 may include a drive device such as a voice coil motor (VCM).

[0045] When the zoom lens actuator control device 100 controls the zoom lens actuator 30 to move the lens units 26a and 26b, the frictional force generated between the guide rail 28 and the lens units 26a and 26b should be taken into account. In particular, since the static friction of the lens units acting until the lens units 26a and 26b stop on the guide rail 28 move to the target position according to the position command causes a response delay, the zoom lens actuator control device 100 should take into account the static friction of these lens units and control the zoom lens actuator 30 to generate an appropriate driving force.

[0046] Figure 3 A zoom lens actuator control device 100 according to an embodiment of the present invention is shown.

[0047] like Figure 3 As shown, a zoom lens actuator control device 100 according to an embodiment of the present invention includes: a command sensing unit 110, a first control unit 120, a second control unit 130 and a control switching unit 140, and according to the embodiment, may also include a switching time notification unit 150.

[0048] The command sensing unit 110 is configured to sense a position command for moving a lens unit stopped at one position on the guide rail 28 to a target position on the guide rail 28. In this case, the command sensing unit 110 may be configured to sense the occurrence of the position command and the direction of movement of the lens unit according to the position command.

[0049] The first control unit 120 is used to determine the initial driving force required to move the target lens unit toward the target position and generate an initial control signal u. c This causes the zoom lens actuator 30 to generate a corresponding initial driving force.

[0050] The second control unit 130 is configured to generate subsequent control signals to perform PID (Proportional Integral Derivative) control on the zoom lens actuator 30 until the moving target lens unit is placed at the target position.

[0051] For example, the second control unit 130 can combine proportional control, derivative control, and integral control to generate subsequent control signals for controlling the zoom lens actuator 30. The proportional control is achieved by multiplying an error signal e, representing the error between the reference signal x* and the current signal x, by an appropriate proportional constant gain K. P To generate the control signal, differential control multiplies the error signal e by an appropriate gain K. D The derivative generates the control signal, and the integral control multiplies the error signal e by an appropriate gain K. I The control signal is generated by the post-integration.

[0052] The control switching unit 140 is configured to transmit the initial control signal of the first control unit 120 to the zoom lens actuator 30 before the predetermined control switching time point arrives after the command sensing unit 110 senses a position command. When the control switching time point arrives, it transmits the subsequent control signal of the second control unit 130 to the zoom lens actuator 30 to replace the initial control signal of the first control unit 120, thereby switching the control unit for switching the zoom lens actuator 30 from the first control unit 120 to the second control unit 130.

[0053] At this time, the second control unit 130 refers to the initial control signal transmitted to the first control unit 120 of the zoom lens actuator 30 before the control switching time point arrives, and generates a subsequent control signal so that when the control switching time point arrives, the zoom lens actuator 30 generates a subsequent driving force within a predetermined range of the difference from the initial driving force, thereby preventing the phenomenon of abrupt changes in the driving force of the zoom lens actuator 30 during the control switching process.

[0054] The switching time notification unit 150 is configured to use timer 152 to measure the time elapsed after the corresponding position command is sensed when the command sensing unit 110 senses a position command, and if the measured time reaches a predetermined reference time, notify the control switching unit 140 that the control switching time point has arrived.

[0055] Figure 4 The force acting on the lens unit 26 located on the guide rail 28 is shown.

[0056] like Figure 4 As shown, when the guide rail 28 of the zoom lens 20 is tilted according to the orientation of the zoom camera 2, forming an angle θ with the perpendicular direction corresponding to the direction of gravity, and the lens unit 26 is moved in the magnification direction, the driving force f of the zoom lens actuator 30 is... a The frictional force f acts in the direction of amplification. f Direction and driving force f a The opposite direction is the reduction direction effect. Based on the inclination of the guide rail 28 and gravity, the external force f acting on the lens unit 26... d It can be represented as Equation 1.

[0057] Formula 1

[0058] f d =-mg cosθ

[0059] In Equation 1, m is the mass of lens unit 26, and g is the acceleration due to gravity.

[0060] If the driving force f of the zoom lens actuator 30 is... a With external force f d The sum of forces is defined as f(=f a +f d The frictional force f acting on lens unit 26 is... f It can be represented as Equation 2.

[0061] Formula 2

[0062]

[0063] In Equation 2, It is the velocity of lens unit 26, F SIt is the maximum static friction force of lens unit 26, F D It is the kinetic friction force of lens unit 26, and sgn is a sign function.

[0064] Therefore, the actual thrust f' generated on the lens unit 26 can be expressed as Equation 3.

[0065]

Formula 3

[0066]

[0067] In Equation 3, x is the velocity of lens unit 26, and f is the driving force f of zoom lens actuator 30. a The external force f acting on lens unit 26 d The resultant force, F S F is the maximum static friction force of lens unit 26. D It is the kinetic friction force of lens unit 26, and sgn is a sign function.

[0068] That is, when the lens unit 26 is in a stopped state, the driving force f acting on the lens unit 26 a and external force f d The resultant force f is less than the maximum static friction force F. S At that time, the actual thrust f' generated on lens unit 26 becomes 0.

[0069] Furthermore, when the lens unit 26 is in a stopped state, the driving force f acting on the lens unit 26 a and external force f d The resultant force f is greater than the maximum static friction force F. S At that time, the actual thrust f' generated on lens unit 26 becomes fF S .

[0070] Furthermore, when the lens unit 26 is in a moving state, the driving force f acting on the lens unit 26 a and external force f d The resultant force f is greater than the maximum static friction force F. S At that time, the actual thrust f' generated on lens unit 26 becomes fF D .

[0071] Because frictional force varies discontinuously depending on whether the force applied is above or below the maximum static friction, it is difficult to apply an accurate compensating force.

[0072] To compensate for the friction of a moving target object, a method can be used to measure the speed of the target object using a predetermined sensor to determine whether the target object is currently stationary or moving. Then, based on the determination, the maximum static or dynamic friction force of the target object is added to the driving force calculated by the controller. However, when this method is applied to a zoom camera, an additional sensor capable of accurately and quickly measuring the speed of the lens unit is required, which increases the manufacturing cost of the zoom camera. Furthermore, in the case of zoom camera 2, since the position of the lens unit 26 is measured using a Hall sensor 50, the above method is not suitable. If the speed of the lens unit 26 is measured by differentiating the position measured by the Hall sensor 50, excessive noise is generated in this process, making it impossible to accurately determine the magnitude and direction of the speed. Further application of an LPF (Low Pass Filter) to remove noise not only increases the complexity and manufacturing cost of the zoom camera but also reduces the response speed.

[0073] Therefore, the first control unit 120 uses a relatively simple calculation formula to control the zoom lens actuator 30 to generate an initial driving force to compensate for the maximum static friction of the lens unit 26. This reduces the complexity of the zoom camera, saves manufacturing costs, and improves response speed.

[0074] For example, when the lens unit 26 needs to move in the magnification direction according to the position command, the zoom lens actuator 30 needs to generate an initial driving force f under the control of the first control unit 120. c and the external force f acting on lens unit 26 d The resultant force must be greater than the maximum static friction force F of lens unit 26. S Therefore, the initial driving force f c It can be represented as Equation 4.

[0075]

Formula 4

[0076] f c >F s -f d

[0077] In Equation 4, f c The initial driving force F calculated by the first control unit 120 s f is the maximum static friction force of lens unit 26. d This refers to the external force acting on the lens unit 26.

[0078] Therefore, when the lens unit 26 needs to move in the magnification direction according to the position command, the first control unit 120 can calculate the initial driving force f using the calculation formula as shown in Equation 5. c .

[0079]

Formula 5

[0080] f c =F s -f d +f m

[0081] In Equation 5, f c The initial driving force F calculated by the first control unit 120 S f is the maximum static friction force of lens unit 26. d f is the external force acting on lens unit 26. m To ensure the initial driving force f c and external force f d The resultant force is greater than the maximum static friction force F. S The margin value.

[0082] Furthermore, when the lens unit 26 needs to move in the shrinking direction according to the position command, the zoom lens actuator 30 needs to generate an initial driving force f under the control of the first control unit 120. c It can be represented as Equation 6.

[0083]

Formula 6

[0084] f c <-F s -f d

[0085] In Equation 6, f c The initial driving force F calculated by the first control unit 120 S f is the maximum static friction force of lens unit 26. d This refers to the external force acting on the lens unit 26.

[0086] Therefore, when the lens unit 26 needs to move in the magnification direction according to the position command, the first control unit 120 can calculate the initial driving force f using the calculation formula as shown in Equation 7. c .

[0087]

Formula 7

[0088] f c =-F s -f d -f m ′

[0089] In Equation 7, f c The initial driving force F calculated by the first control unit 120 S f is the maximum static friction force of lens unit 26. d f is the external force acting on lens unit 26. m To ensure the initial driving force -f c and external force -fd The resultant force is greater than the maximum static friction force F. S The margin value.

[0090] Figure 5 A first control unit 120 of a zoom lens actuator control device according to an embodiment of the present invention is shown.

[0091] like Figure 5 As shown, the first control unit 120 includes an initial driving force calculation module 126 and a control signal generation module 128. According to the embodiment, it may also include a friction force information providing module 122 and an external force information providing module 124.

[0092] The friction information providing module 122 can be configured to refer to a friction information table on the guide rail 28 that records the maximum static friction of the lens unit 26 according to the direction of movement and position, and provide the initial driving force calculation module 126 with the maximum static friction information F corresponding to the current position x of the lens unit 26 and the movement direction sgn(x*-x) according to the position command x*. S In this case, the friction information providing module 122 can pre-store a first friction information table applied when the lens unit moves in the magnification direction and a second friction information table applied when the lens unit moves in the reduction direction.

[0093] The external force information providing module 124 can be configured to acquire external force information (ax = -g cosθ) acting on the lens unit 26 via a sensor for sensing the posture or tilt of the guide rail 28, and provide the acquired external force information ax to the initial driving force calculation module 126. In this case, the external force information providing module 124 can be configured to acquire the corresponding external force information ax from the accelerometer mounted on the zoom camera 2 for optical image stabilization (OIS).

[0094] The initial driving force calculation module 126 can be configured to consider the movement direction of the lens unit 26 according to the position command, and the maximum static friction force F of the lens unit 26. s The tilt of the guide rail 28 and the external force ma exerted by gravity on the lens unit 26 x Calculate the initial driving force f of the zoom lens actuator 30. c .

[0095] The control signal generation module 128 can be configured to generate an initial driving force f corresponding to the calculation. c initial control signal u c In this case, the initial control signal u c It can be generated as a response to the calculated initial driving force f cMultiply by the preset scaling factor (1 / k) a The value obtained is ).

[0096] Figure 6 This is a graph showing the starting current of the lens unit based on its position.

[0097] like Figure 6 As shown, with the lens unit stationary on the guide rail, the current input to the zoom lens actuator is gradually increased to measure the starting current input when the lens unit begins to move. The results show different current values ​​depending on the position and direction of movement of the lens unit. That is, the maximum static friction force acting on the lens unit varies depending on the position and direction of movement of the lens unit.

[0098] Therefore, the friction information providing module 122 of the first control unit 120 pre-stores a friction information table on the guide rail 28 that records the maximum static friction value of the lens unit 26 according to the moving direction and position, and can transmit the maximum static friction information F corresponding to the current position x of the lens unit 26 and the moving direction according to the position command. S Provided to the initial driving force calculation module 126.

[0099] Figure 7 The graphs show a comparison of the response characteristics of existing PID control methods and the present invention.

[0100] like Figure 7 As shown, in the existing PID control method, even if the user inputs a position command at time t1, generating the driving force of the zoom lens actuator, the lens unit cannot move immediately due to the static friction of the lens unit stationary on the guide rail. Instead, a response delay occurs until time t2, when the driving force of the zoom lens actuator is sufficiently increased through proportional-integral control. Furthermore, because the existing PID control method applies excessive driving force to the lens unit to overcome its static friction, the lens unit moves abruptly at the moment the static friction switches to dynamic friction, resulting in overshoot.

[0101] Furthermore, in this invention, when a position command is sensed at time t1, the first control unit performs initial control to respond immediately, causing the zoom lens actuator to generate a predetermined initial driving force, so that the corresponding lens unit moves toward the target location without delay. Moreover, when the lens unit starts to move, the control is switched at time ts, so that the second control unit performs PID control on the zoom lens actuator. In this way, response delay caused by static friction of the lens unit can be prevented, while overshoot caused by excessive driving force can be minimized.

[0102] Furthermore, embodiments of the present invention can be implemented by a computer system and a computer program for driving the computer system. When embodiments of the present invention are implemented by a computer program, the constituent elements of the present invention may include program segments that perform corresponding operations or tasks through the corresponding computer system. These computer programs and even program segments may be stored in various computer-readable recording media. Computer-readable recording media may include all types of media on which data that can be read by a computer system is recorded. For example, computer-readable recording media may include ROM, RAM, EEPROM, registers, flash memory, CD-ROM, magnetic tape, hard disk, floppy disk, or optical data recording devices, etc. In addition, such recording media may be distributed across computer systems connected via various networks to store or execute program code in a distributed manner.

[0103] As described above, according to the present invention, when a position command is detected for moving a lens unit stopped at one position on the guide rail to a target position on the guide rail, the first control unit performs initial control to generate a predetermined initial driving force in the zoom lens actuator so that the corresponding lens unit can move towards the target location without delay. When the lens unit starts to move, the second control unit performs PID control on the zoom lens actuator until the lens unit is placed at the target position according to the position command. Thus, while preventing response delay caused by static friction of the lens unit, overshoot caused by excessive driving force can be minimized.

[0104] Furthermore, since the first control unit controls the zoom lens actuator without any additional signals that cause vibration (such as a knock signal), the vibration generated during the operation of the zoom lens actuator can be reduced.

[0105] Furthermore, the first control unit does not use a complex calculation model, but instead uses a relatively simple calculation formula that takes into account the maximum static friction of the lens unit and the external force acting on the lens unit to calculate the initial driving force of the zoom lens actuator, thereby simplifying the zoom magnification adjustment system of the zoom camera and reducing manufacturing costs.

[0106] Furthermore, of course, according to embodiments of the present invention, various other technical problems besides those mentioned in this specification can be solved not only in the field of this invention but also in related technical fields.

[0107] The present invention has been described above with reference to specific embodiments. However, those skilled in the art will clearly understand that various modified embodiments can be implemented within the technical scope of the present invention. Therefore, the embodiments disclosed above should be considered from an illustrative rather than a limiting perspective. That is, the true technical spirit and scope of the present invention are shown in the claims, and should be interpreted as including all differences within the equivalent scope of the present invention.

Claims

1. A zoom lens actuator control device, which is a control device for changing the zoom magnification of a zoom lens by controlling a zoom lens actuator for moving a lens unit of a zoom lens along a guide rail arranged inside the zoom lens, wherein... include: A command sensing unit is used to sense position commands to move a lens unit that is stopped at a position on the guide rail toward a target position on the guide rail; A first control unit is configured to generate an initial control signal, causing the zoom lens actuator to generate a predetermined initial driving force required to move the lens unit toward the target position. The second control unit is used to generate subsequent control signals to perform PID (Proportional Integral Derivative) control on the zoom lens actuator until the lens unit is placed at the target position; as well as After the command sensing unit senses the position command, the control switching unit transmits the initial control signal of the first control unit to the zoom lens actuator before the predetermined control switching time point arrives. When the control switching time point arrives, the control switching unit transmits the subsequent control signal of the second control unit to the zoom lens actuator to replace the initial control signal of the first control unit. The first control unit includes: The initial driving force calculation module calculates the initial driving force by considering the movement direction of the lens unit according to the position command, the maximum static friction of the lens unit, and the external forces acting on the lens unit by the tilt of the guide rail and gravity; and The control signal generation module is used to generate an initial control signal corresponding to the calculated initial driving force. The first control unit further includes a friction information providing module, which refers to a friction information table on the guide rail that records the maximum static friction of the lens unit according to the direction of movement and position, and provides the initial driving force calculation module with the maximum static friction information corresponding to the direction of movement of the lens unit according to the position command and the current position of the lens unit.

2. The zoom lens actuator control device according to claim 1, wherein, The first control unit further includes an external force information providing module, which obtains external force information through a sensor for sensing the posture or tilt of the guide rail, and provides the obtained external force information to the initial driving force calculation module.

3. The zoom lens actuator control device according to claim 1, wherein, The second control unit refers to the initial control signal transmitted to the zoom lens actuator before the control switching time point arrives, and generates a subsequent control signal so that the zoom lens actuator generates a subsequent driving force with a difference from the initial driving force within a predetermined value when the control switching time point arrives.

4. The zoom lens actuator control device according to claim 1, wherein, It also includes a switching time notification unit, which measures the time elapsed since the location command was sensed by the command sensing unit, and notifies the control switching unit that the control switching time has arrived when the measured time reaches a predetermined reference time.

5. A zoom camera using a zoom lens actuator control device according to any one of claims 1 to 4.

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