JP3809231B2 - LENS CONTROL METHOD, LENS CONTROL DEVICE, PROGRAM, AND STORAGE MEDIUM - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a lens control method for controlling a lens of a lens system provided in an imaging apparatus such as a still camera or a video camera., Lens controlapparatus,Program for controlling the lens control deviceAnd the programIt relates to the storage medium which stored.
[0002]
[Prior art]
In the field of consumer still cameras and video cameras, the demand for miniaturization and lightening has been increasing rapidly in recent years, and the development of compact and high-performance lens systems has been steadily advanced accordingly.
[0003]
In the field of consumer video cameras, instead of the front-focus lens system that was the mainstream until several years ago, in recent years there have been many rear-focus lens systems that perform focusing operations using lenses other than the front lens. Has been introduced. The front lens type is a lens system that focuses on the lens closest to the subject, and moves the DC motor, reduction gear, zoom lens, and lens for driving the large front lens in conjunction with each other. As a whole, it is inevitable to increase the size.
[0004]
On the other hand, the rear focus type lens system drives a lighter lens at the rear stage, so that a reduction gear or the like is unnecessary, and a small and relatively small torque actuator can be used. Further, as is well known, by providing a focus lens at the subsequent stage of the variable power lens, a competition function is added to the focus lens and the cam ring is deleted, and these greatly contribute to miniaturization.
[0005]
FIG. 10 is a block diagram illustrating a configuration of an imaging apparatus including a rear focus type lens system. In FIG. 10, reference numeral 1001 denotes a fixed first lens group, and 1002 denotes a second lens group that performs a zooming operation (hereinafter, referred to as a “first lens group”). (Denoted as a zoom lens), 1003 is a diaphragm for adjusting the amount of light, 1004 is a fixed third lens group, and 1005 is a fourth lens group having a focus function and a competition function for correcting movement of the focal plane due to zooming (hereinafter referred to as a zoom lens). , 1006, 1007, and 1008 are a zoom lens 1002, an aperture 1003, and a position encoder for detecting the position of the focus lens 1005, and 1009, 1010, and 1011 are a zoom lens 1002 and an aperture 1003, respectively. , For driving the focus lens 1005 The actuators 1012, 1013, and 1014 are drivers for applying energy to the actuators 1009, 1010, and 1011, 1015 is an image sensor such as a CCD, 1016 is an amplifier, 1017 is a band pass filter, and 1018 is a lens focus and zoom control A control device 1019 such as a microcomputer for performing the aperture is an aperture control device for opening the aperture 1003 by an appropriate amount.
[0006]
In FIG. 10, optical image information sequentially passing through a first lens group 1001, a zoom lens 1002, an aperture 1003, a third lens group 1004, and a focus lens 1005 is photoelectrically converted by an image sensor 1015 and amplified as electrical image information. The band pass filter 1017 is reached via 1016. The band pass filter 1017 extracts only the high frequency component of the electrical video information and transmits it to the control device 1018. The control device 1018 captures the output signal of the bandpass filter 1017 by A / D conversion or the like. As is well known, the amount of high-frequency components included in the video signal when the subject is photographed increases as it approaches the in-focus state, so that the control device 1018 uses the focus compensator to maximize the A / D conversion value. If the position of 1005 is controlled, the focusing operation can be automatically performed.
[0007]
FIG. 11 is a view showing an example of the configuration of an actuator 1011 for driving the focus lens 1005 and a drive transmission system. In the figure, a screw is directly engraved on the output shaft 1101 of the actuator 1011. The output shaft 1101 is rotatably supported by a holding member 1102 via a bearing 1103. Reference numeral 1104 denotes a guide rod. When the output shaft 1101 is rotated by the actuator 1011, the guide rod 1104 prevents the focus compensator lens 1005 from rotating in a plane perpendicular to the optical axis. Therefore, the guide rod 1104 is attached to the focus compensator lens 1005. The rack 1105 is moved in parallel with the optical axis, and the focus competition lens 1005 is also moved in parallel with the optical axis.
[0008]
FIG. 12 is a diagram showing a movement locus of the focus lens 1005 for performing focus surface correction while maintaining focus when zooming is performed with a rear focus type lens system. In FIG. The focus compensator 1005 has a position at the bottom where the focus is at infinity and the top is at the close focus, and the horizontal axis indicates the position of the zoom lens 1002 where the left end is the wide end and the right end is the tele end. As described above, since the focus lens 1005 has both a focus adjustment function and a competition function, the focus position with respect to the subject distance differs for each position of the zoom lens 1002, and each subject distance is used as a parameter as shown in FIG. Sometimes the trajectory varies depending on the subject distance. As can be seen from FIG. 12, when the moving speed of the zoom lens 1002 is constant, the locus is almost linear from the wide to the middle, so the moving speed of the focus lens 1005 does not change greatly, but the inclination of the locus In the vicinity of the middle where the direction changes, the vehicle gradually decelerates, and after almost stopping, the locus of the locus becomes steep near the telephoto end. Therefore, the actuator 1011 of the focus lens 1005 includes a stop, from low speed to high speed. Flexible speed response performance is required. Further, if the movement of the zoom lens 1002 and the movement of the focus competition lens 1005 do not almost completely match, the locus shown in FIG. 12 is deviated, resulting in a noticeable blurring during zooming.
[0009]
Therefore, the actuator 1011 of the focus lens 1005 is required to have wide and accurate speed response, good drive response, and high positional accuracy. An example of a suitable actuator that satisfies such conditions is a stepping motor.
[0010]
In the configuration shown in FIG. 10, when a stepping motor is used for the actuator 1011 of the focus lens 1005, it cannot be driven normally unless the load is lightened. However, the focus lens 1005 is relatively light as described above. Even with the configuration as shown in FIG. 11 using a stepping motor, it is possible to drive the motor up to about 500 pps without step-out.
[0011]
Even in actual products, a stepping motor is often used for a focus lens in a rear focus type lens system.
[0012]
Next, the stepping motor driving method is generally one of 1-phase excitation, 2-phase excitation, and 1-2-phase excitation shown in FIGS. 13A, 13B, and 13C, respectively. are categorized. The waveforms on the right side of FIGS. 13A, 13B, and 13C show the phase relationship of the voltages applied to the actuator terminals. Actually, in order to remove noise, vibration, etc., it is not a rectangular wave as shown in the excitation waveform of FIG. 13, but a trapezoidal wave with a rising and falling slope, a rising or falling sine wave. The waveform may be lowered, but the phase relationship does not change.
[0013]
FIG. 14 is a diagram showing the state of rotation of the rotor of the stepping motor by each excitation method. The stepping motor used here has two coils of A-Abar phase and B-Bbar phase, A magnetic field generated from the coil is guided to the position shown in FIG.
[0014]
In the case of one-phase excitation, as shown in FIG. 14 (a), the rotor magnetic pole moves so as to always face the stator magnetic pole. That is, when attention is paid to the magnetic poles with arrows of the rotor in FIG. 14, since the Abar phase is N in the state 1 in FIG. 13A, the rotor is changed to the Abar phase in (1) in FIG. S poles marked with an arrow are facing each other. In the state 2 in FIG. 13A, the Bbar phase becomes N, and in FIG. 14A 2B, the magnetic pole with the rotor arrow moves to the Bbar phase. That is, a rotation of 18 ° can be obtained by one change of the magnetic pole of the stator.
[0015]
In the case of two-phase excitation, the change of the magnetic field as shown in FIG. 13B is shown, and the rotation of the rotor is as shown in FIG. 14B. In the case of two-phase excitation, the rotor moves so as to oppose the magnetic pole of the stator so as to face the middle of the magnetic pole. .
[0016]
In the case of 1-2 phase excitation, since one-phase excitation and two-phase excitation are repeated, when rotation starts from a position facing the stator magnetic pole, the next change in the magnetic pole causes a change between the stator magnetic pole and the magnetic pole. The rotor moves so as to face the adjacent magnetic pole by the next change in magnetic pole. As a result, the amount of rotation obtained by one change in the magnetic pole of the stator is 9 ° corresponding to 1/2 of the one-phase excitation and the two-phase excitation.
[0017]
By the way, when it is not necessary to move the lens while maintaining the current lens position, for each excitation method shown in FIG. 14, a current is continuously supplied to the motor coil so as to maintain the excitation phase at that time. Since the motor is not rotated, that is, the excitation phase does not change, this holding current is a direct current. Since the load is only the coil, the magnitude of the holding current is several tens to several hundred mA per coil, and the heat generation is also a considerable amount.
[0018]
FIG. 15 is a flowchart of processing in the control device 1018 for performing an operation of reducing the holding current when the motor is stopped. By applying this control output to a drive circuit described later, the electric power during motor stop is shown. Consumption can be reduced.
[0019]
In FIG. 15, first, a “drive enable flag” for permitting motor drive is set to 1 in step S1501, and it is determined in a next step S1502 whether a command output by another process is a lens stop command. If no lens stop command is output, it is determined in step S1511 whether the “drive enable flag” is 1. If the “drive enable flag” is 1, the value of the counter N is set to 0 in step S1517. clear. Next, in step S1518, the lens is driven according to the drive command, and then the process returns to step S1502.
[0020]
On the other hand, if a lens stop command is output in step S1502, it is determined in step S1503 whether the drive enable flag is 1. If the drivability flag is 1, in step S1504, the driving pulse is stopped and the motor is stopped so that the holding current flows. Next, in step S1505, it is determined whether or not the value of the counter N is a predetermined value (for example, 240) or more. If the value of the counter N is less than the predetermined value, the value of the counter N is incremented in step S1506, and the process returns to step S1502. Then, the state in which the holding current is supplied is continued until the value of the counter N reaches a predetermined value, thereby forming a stable stop state.
[0021]
If the value of the counter N is greater than or equal to the predetermined value in step S1505, the counter value N is cleared to 0 in step S1507, and the “drive enable flag” is set to 0 in the next step S1508. Next, after reducing the holding current in step S1509, the process returns to step S1502.
[0022]
The counter N is provided to absorb the motor shake immediately after the stop as shown in FIG. 16 and to form a stable stop state and to monitor whether the stop state continues for a while. In consideration of the case where the restart is immediately performed, the current limit is not applied by the counter N in order to perform the restart smoothly.
[0023]
On the other hand, once the “drive enable flag” is set to 0 in step S1508 and the holding current is reduced in step S1509, the determination in step S1503 is performed while the stop command is continuously output in step S1502. Since the result is negative (NO), the holding current reduction operation continues in step S1509 while setting the value of a counter M described later in step S1510 to zero.
[0024]
When the lens driving command is output again, the determination result in step S1502 is negative (NO). Therefore, it is determined in step S1511 whether the “drive enable flag” is 1. If the “drive enable flag” is 0, the holding current is returned to the original state in step S1512, and in the next step S1513, it is determined whether or not the value of the counter M is a predetermined value (for example, 60) or more. If the value of the counter M is smaller than the predetermined value, the value of the counter M is incremented in step S1516, and the process returns to step S1502. If the value of the counter M is greater than or equal to the predetermined value in step S1513, the value of the counter M is cleared to 0 in step S1514, and the “drive enable flag” is set to 1 in the next step S1515. After step S152 and step S1511, the value of the counter N is cleared to 0 in step S1517, and then the motor is driven in accordance with the drive command in step S1518. The counter M is provided in order to restore the motor holding current to the original state and realize the movement of the magnetic pole with a sufficient torque when the motor is driven.
[0025]
When the motor stop command is output again before the value of the counter M is less than the predetermined value, the “drive enable flag” remains 0 through the step S1502 to the step S1503, and the motor is also stopped. Since the value of the counter M is cleared to 0 in step S1510, the operation immediately proceeds to the holding current reduction operation in step S1509. If the motor drive command is output again before the value of the counter N is less than the predetermined value, the “drive enable flag” remains 1, and the holding current value is also maintained immediately after the stop. Therefore, after the step S1511, the value of the counter N is cleared to 0 in the step S1517, and the process immediately shifts to the motor drive operation according to the drive command.
[0026]
By performing the above processing, if it takes some time after entering the stop state and the stop state continues as it is, the amount of current supplied to the motor is suppressed at the stop position to save current and generate heat. Can be suppressed.
[0027]
Next, the case where the process of FIG. 15 is applied to each of (a), (b), and (c) of FIG. 14 will be described.
[0028]
In the case of the one-phase excitation shown in FIG. 14 (a), even if the holding current is completely cut off when the motor is stopped, the magnetic poles of the rotor and the stator always stop facing each other. It is possible to prevent a rotor from rotating by attracting a certain rotor to a metal stator to some extent. Further, at least in the structure as shown in FIG. 11, even if a force is applied to move the lens parallel to the optical axis and consequently rotate the rotor, the force is not so large due to the mechanical structure. The rotor cannot be rotated.
[0029]
FIG. 17 is a diagram showing how the motor is energized according to the process of FIG.
[0030]
FIG. 18 is a block diagram showing an internal configuration of the zoom motor driver 1012 or the focus motor driver 1014 in FIG. 10 having a function of interrupting energization of the motor in a stopped state when the motor is rotated by one-phase excitation. In FIG. 18, reference numeral 1801 denotes a drive control circuit that outputs an excitation pattern to the zoom motor driver 1012 or the focus motor driver 1014. When applied to FIG. 10, the drive pulse is sent out by the control device 1018, and the drive current according to the drive pulse. Is output by the zoom motor driver 1012 or the focus motor driver 1014.
[0031]
In FIG. 18, 1802 and 1803 are switches for controlling on / off of energization to the coils of the A-Abar phase and the B-Bbar phase, respectively, 1804 is a switch control circuit for controlling these switches 1802 and 1803, 1805 Reference numeral 1807 denotes an H (high) bridge circuit of A-Abar phase and B-Bbar phase, 1806 and 1808 denote stator coils in the motor of A-Abar phase and B-Bbar phase, and 1809 denotes a power source.
[0032]
In accordance with the flowchart shown in FIG. 19, the switch control circuit 1804 controls the switches 1802 and 1803 so that the energization is interrupted if the holding current is reduced, and the energization is performed if the holding current is not reduced.
[0033]
The process shown in FIG. 19 is executed in response to the process of FIG. 15 described above, and the motor drive / stop command is output in the control device 1018 of FIG. 10, and the switch control circuit 1804 of FIG. Is included in the controller 1018 of FIG.
[0034]
In FIG. 19, first, in step S1901, it is determined whether or not a motor stop command is output. If the motor stop command is not output, the switches 1802 and 1803 are closed (turned on) in step S1904 so that the drive current can be applied, and the process returns to step S1901. If a motor stop command is output in step S1901, it is determined in step S1902 whether a holding current reduction command is output. If the holding current reduction command is not output, the switches 1802 and 1803 are closed (turned on) in step S1904 so that the drive current can be passed, and the process returns to step S1901. If a holding current reduction command is output in step S1902, the switches 1802 and 1803 are opened (turned off) in step S1903, the power supply to the motor is cut off, and the process returns to step S1901.
[0035]
By performing the above processing, it is possible to realize power saving while stopping in the one-phase excitation.
[0036]
Next, consider the case of two-phase excitation.
[0037]
As shown in FIG. 14B, in two-phase excitation, the magnetic pole of the rotor always stops opposite to the middle of two adjacent magnetic poles of the stator. When energization of the stator coil is interrupted in the stopped state as in the one-phase excitation described above, the rotor is opposed to either the left or right stator due to the assembly error of the magnetic poles of the stator or a slight deviation of the stop position. It is predicted to move by two steps. That is, in the case of two-phase excitation, it is necessary to excite the stator even in the stopped state. In other words, in the case of two-phase excitation, it is necessary to energize at least a current that ensures a magnetic field that holds the rotor stop position.
[0038]
Accordingly, the motor drive circuit having the configuration shown in FIG. 20 can suppress the amount of current in the stopped state. FIG. 20 is a block diagram showing the internal configuration of the motor drive circuit in the case of two-phase excitation. In FIG. 10, reference numeral 2001 denotes a drive control circuit for sending an excitation pattern to the zoom motor driver 1012 or the focus motor driver 1014. In FIG. 10, the excitation pattern is sent by the control device 1018, and driving according to the excitation pattern is performed. Current output is performed by the zoom motor driver 1012 or the focus motor driver 1014.
[0039]
In FIG. 20, 2002 and 2003 are switches that are switched so as to be connected to 1 when the motor is driven and 2 when the holding current is reduced, and 2004 is in the control device 1018 of FIG. 10, and these switches 2002 and 2003 are connected. Switch control circuits to be controlled, 2005 and 2007 are H (high) bridge circuits, 2006 and 2008 are stator coils in the motor, and 2009 is a power source.
[0040]
The control of the switch control circuit 2004 is executed according to the flowchart shown in FIG. 21, and the processing of FIG. 21 is executed in response to the processing of FIG.
[0041]
In FIG. 21, first, in step S2101, it is determined whether or not a motor stop command is output. If the motor stop command is not output, the switches 2002 and 2003 are grounded to energize the motor coil in step S2104, and the process returns to step S2101. If a motor stop command is output in step S2101, it is determined in step S2102 whether a holding current reduction command is output. If the holding current reduction command is not output, the switches 2002 and 2003 are grounded in step S2104 to enable the original energization of the motor, and the process returns to step S2101. If a holding current reduction command is output in step S2102, the switches 2002 and 2003 are grounded via a resistor in step S2103, and the suppressed holding current is allowed to flow while suppressing energization of the motor. After doing so, the process returns to step S2101.
[0042]
FIG. 22 is a block diagram showing an internal configuration of the power saving motor drive circuit in the case of 1-2 phase excitation of FIG. In FIG. 10, reference numeral 2201 denotes a drive control circuit that outputs an excitation pattern to the zoom motor driver 1012 or the focus motor driver 1014. In FIG. 10, the drive pulse is sent out by the control device 1018, and the drive current according to the drive pulse. Is output by the zoom motor driver 1012 or the focus motor driver 1014.
[0043]
In FIG. 22, reference numerals 2202 and 2203 denote switches for switching energization amounts to the A-Abar phase and B-Bbar phase coils, and 2204 denotes a switch control circuit for controlling these switches 2202 and 2203. The switch control circuit 2204 and the drive control circuit 2201 are connected via a communication path 2210 so that the switch control circuit 2204 can grasp whether the motor excitation state at that time is two-phase or one-phase. 2205 and 2207 are H (high) bridge circuits of the A-Abar phase and the B-Bbar phase, 2206 and 2208 are stator coils in the motor of the A-Abar phase and the B-Bbar phase, and 2209 is a power source. .
[0044]
The control of the drive control circuit 2201 is executed according to the flowchart of FIG.
[0045]
In FIG. 23, first, in step S2301, it is determined whether or not a motor stop command is output. If no motor stop command is output, the switches 2202 and 2203 are grounded to energize the motor coil in step S2306, and the process returns to step S2301. If a motor stop command is output in step S2301, it is determined in step S2302 whether a holding current reduction command is output. If the holding current reduction command is not output, the switches 2202 and 2203 are grounded in step S2306 to enable the original energization of the motor, and the process returns to step S2301. If a holding current reduction command is output in step S2302, it is determined in step S2303 whether the current stop position is a two-phase stop position. If the current stop position is the two-phase stop position, the switches 2202 and 2203 are grounded via a resistor in step S2305, and a current sufficient to hold the current motor position is allowed to flow. The process returns to step S2301.
[0046]
In step S2303, when the current stop position is not the two-phase stop position, that is, in the case of the one-phase stop position, the switches 2202 and 2203 are opened (turned off) in step S2304 to turn off the power, and then the step The process returns to S2301.
[0047]
As described above, the holding current can be reduced by identifying the two-phase stop position and the one-phase stop position and changing the current amount limiting method.
[0048]
[Problems to be solved by the invention]
However, in the above-described conventional example, once the motor holding current is reduced, the motor holding current is restored to the original state upon restarting the mohet, and then the lens is driven smoothly. It is necessary to keep the time and the excitation state. That is, once the motor holding current is reduced, the predetermined time always elapses after the drive command is output until the motor is actually driven, and this is a factor that hinders the speed of the autofocus operation. It was.
[0049]
  The present invention has been made in view of the above-described problems of the prior art, and the first object of the present invention is that the higher the frequency, the more difficult it is to shift to the holding current reduction operation. Lens control method, Lens controlapparatusAnd programsIs to provide.
[0050]
  A second object of the present invention is to provide a lens control method that makes it difficult to shift to a holding current reduction operation when there is a lot of camera shake., Lens controlapparatusAnd programsIs to provide.
[0051]
  A third object of the present invention is to provide a lens control method that makes it difficult to shift to a holding current reduction operation when the depth of field of the lens is low., Lens controlapparatusAnd programsIs to provide.
[0052]
Furthermore, a fourth object of the present invention is to provide a storage medium storing a control program for controlling the lens control device of the present invention as described above.
[0053]
[Means for Solving the Problems]
  In order to achieve the first object, a lens control method according to claim 1 is provided in a lens driving means for driving a lens.Holding the lens in place by supplying a holding currentA lens control method,A holding current supplying step for supplying a holding current to the lens driving unit for a predetermined time when the lens driving unit stops driving the lens; and the holding current to the lens driving unit for the predetermined time. A supply current limiting step for limiting the supply of the holding current;When the focal length of the lens is the first focal lengthThe firstCompared to the case of the second focal length shorter than the focal length of oneSwitching step for increasing the predetermined timeIt is characterized by having.
[0054]
  MaBillingThe lens control method according to Item 2, in the lens control method according to Claim 1,The first and second focal lengths are adjusted by a zoom lens capable of zooming.
[0055]
  In order to achieve the second object, a lens control method according to claim 3 is provided in a lens driving means for driving a lens.Holding the lens in place by supplying a holding currentA lens control method,A holding current supplying step for supplying a holding current to the lens driving unit for a predetermined time when the lens driving unit stops driving the lens; and the holding current to the lens driving unit for the predetermined time. A supply current limiting step for limiting the supply of the holding current;When the vibration amount of the lens is the first vibration amountThe firstCompared to the second vibration amount smaller than the first vibration amountSwitching step for increasing the predetermined timeIt is characterized by having.
[0056]
  In order to achieve the third object, a lens control method according to claim 4 is provided in a lens driving means for driving a lens.Holding the lens in place by supplying a holding currentA lens control method,A holding current supplying step for supplying a holding current to the lens driving unit for a predetermined time when the lens driving unit stops driving the lens; and the holding current to the lens driving unit for the predetermined time. A supply current limiting step for limiting the supply of the holding current;The aperture value of the aperture mechanism that adjusts the amount of light passing through the lens is the first aperture value.The firstCompared to the second aperture value, which is larger than the aperture value of 1.Switching step for increasing the predetermined timeIt is characterized by having.
[0057]
  The lens control method according to claim 5 is the lens control method according to any one of claims 1 to 4, wherein the driving of the lens is as follows.Stepping motorIt is performed using.
[0058]
  In order to achieve the first object, a lens control device according to claim 6 includes lens driving means for driving the lens.Holding the lens in place by supplying a holding currentA lens control device,When the lens driving unit stops driving the lens, a holding current supplying unit supplies a holding current to the lens driving unit for a predetermined time; and the holding current is supplied to the lens driving unit for the predetermined time. Supply current limiting means for limiting the supply of the holding current,When the focal length of the lens is the first focal lengthThe firstCompared to the case of the second focal length shorter than the focal length of oneSwitching means for lengthening the predetermined timeIt is characterized by having.
[0059]
  In order to achieve the second object, a lens control device according to claim 7 includes lens driving means for driving a lens.Holding the lens in place by supplying a holding currentA lens control device,When the lens driving unit stops driving the lens, a holding current supplying unit supplies a holding current to the lens driving unit for a predetermined time; and the holding current is supplied to the lens driving unit for the predetermined time. Supply current limiting means for limiting the supply of the holding current,When the vibration amount of the lens is the first vibration amountThe firstCompared to the second vibration amount smaller than the first vibration amountSwitching means for lengthening the predetermined timeIt is characterized by having.
[0060]
  In order to achieve the third object, a lens control device according to claim 8 is provided in a lens driving means for driving a lens.Holding the lens in place by supplying a holding currentA lens control device,When the lens driving unit stops driving the lens, a holding current supplying unit supplies a holding current to the lens driving unit for a predetermined time; and the holding current is supplied to the lens driving unit for the predetermined time. Supply current limiting means for limiting the supply of the holding current,The aperture value of the aperture mechanism that adjusts the amount of light passing through the lens is the first aperture value.The firstCompared to the second aperture value, which is larger than the aperture value of 1.Switching means for lengthening the predetermined timeIt is characterized by having.
[0061]
  In order to achieve the first object, a program according to claim 9 is provided in a lens driving means for driving a lens.Holding the lens in place by supplying a holding currentA program for causing a computer to execute a lens control method,When the lens driving unit stops driving the lens, a holding current supply module that supplies a holding current to the lens driving unit for a predetermined time, and the holding current to the lens driving unit for the predetermined time. Supply current limiting module for limiting the supply of the holding current,When the focal length of the lens is the first focal lengthThe firstCompared to the case of the second focal length shorter than the focal length of oneSwitching module for extending the predetermined timeAnd making the computer execute.
[0062]
  In order to achieve the second object, a program according to claim 10 is provided in a lens driving means for driving a lens.Holding the lens in place by supplying a holding currentA program for causing a computer to execute a lens control method,When the lens driving unit stops driving the lens, a holding current supply module that supplies a holding current to the lens driving unit for a predetermined time, and the holding current to the lens driving unit for the predetermined time. Supply current limiting module for limiting the supply of the holding current,When the vibration amount of the lens is the first vibration amountThe firstCompared to the second vibration amount smaller than the first vibration amountSwitching module for extending the predetermined timeAnd making the computer execute.
[0063]
  In order to achieve the third object, a program according to claim 11 is provided in a lens driving means for driving a lens.Holding the lens in place by supplying a holding currentA program for causing a computer to execute a lens control method,When the lens driving unit stops driving the lens, a holding current supply module that supplies a holding current to the lens driving unit for a predetermined time, and the holding current to the lens driving unit for the predetermined time. Supply current limiting module for limiting the supply of the holding current,The aperture value of the aperture mechanism that adjusts the amount of light passing through the lens is the first aperture value.The firstCompared to the second aperture value, which is larger than the aperture value of 1.A switching module for extending the predetermined time;Is executed by a computer.
[0064]
  In addition, the above4To achieve the purpose of,Claim 12Storage mediaIsA program according to any one of claims 9 to 11 is stored.
[0083]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to FIGS.
[0084]
(First embodiment)
First, a first embodiment of the present invention will be described with reference to FIGS. Note that the basic configuration of the imaging apparatus provided with the lens control apparatus according to the present embodiment is the same as that of the conventional FIG. 10 and FIG. 11 described above.
[0085]
FIG. 1 is a flowchart showing a control procedure of processing operations in the control device 1018 in the imaging apparatus equipped with the lens control device according to the first embodiment of the present invention. In the figure, steps S101 to S104 and steps S106 to S118 are the same as steps S1501 to S1504 and steps S1506 to S1518 in FIG. 15 described above, so here, processing steps unique to this embodiment will be described. Only explained.
[0086]
As is clear from FIG. 12 described above, in the lens system shown in FIG. 10, the zoom position is wide and telescopic, and the required amount of movement of the focus lens with respect to the subject distance change is different. Therefore, the frequency of restarting the focus lens is high on the tele side where the focal length is long, and conversely, the frequency of restarting the focus lens is low on the wide side where the focal length is short. Actually, the inventor of the present invention measured that the focus lens frequently moves on the tele side, and conversely, on the wide side, it is difficult to move the focus lens even if the same subject is shot. ing. Therefore, regarding the holding current reduction operation after the focus lens driving motor is stopped, the longer the focal length, the more difficult it is to shift to the holding current reduction operation, that is, the longer the time to shift to the holding current reduction operation is. For example, the system is configured to maintain this on the tele side, which requires the quickness of the autofocus operation, and give priority to power saving and suppression of the heat generation amount on the wide side where the stop is frequently performed.
[0087]
In FIG. 15, after stopping the zoom motor 1009 in step S104, the position of the zoom lens 1002 is detected in step S105a of step S105, the value of the variable C is defined according to the focal length corresponding to the position, and then In step S105b of step S105, it is determined whether or not the value of the counter N is greater than or equal to the value of the variable C. If the value of counter N is less than the value of variable C, the value of counter N is incremented in step S106. If the value of counter N is greater than or equal to the value of variable C, the value of counter N is incremented in step S107. Clear 0.
[0088]
Step S105 will be described in detail based on the flowchart of FIG. In FIG. 2, the position of the zoom lens 1002 is detected from the output signal of the position encoder 1006 in FIG. 10 at step S201, step S202, step S203, step S204, and step S205, which are the processing of step S105a in FIG. The value of the variable C is defined in step S206, step S207, step S208, step S209, step S210, and step S211 according to the focal length corresponding to. The numerical value of the condition for determining the position of the zoom lens 1002 in FIG. 2 corresponds to the numerical value of the horizontal axis in FIG. 12, that is, the zoom lens position.
[0089]
After the value of the variable C is defined according to the focal length, it is determined whether or not the value of the counter N is equal to or larger than the value of the variable C in step S212 (step S105b in FIG. 1). If the value of the counter N is less than the value of the variable C, the value of the counter N is incremented in step S106 of FIG. 1, and if the value of the counter N is greater than or equal to the value of the variable C, the step of FIG. In S107, the value of the counter N is cleared to zero.
[0090]
Thus, the operation can be controlled such that the longer the focal length is and the greater the focus movement is relative to the movement of the subject distance, the more difficult it is to shift to the motor holding current reduction operation.
[0091]
(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a block diagram showing a configuration of an imaging apparatus including a lens control device according to the second embodiment of the present invention. In FIG. 3, the same parts as those in FIG. It is. 3 is different from FIG. 10 in that a camera shake sensor 301 for detecting camera shake is added to the configuration of FIG. The detection signal of the camera shake sensor 301 is input into the control device 1018.
[0092]
Although the description of the internal structure of the camera shake sensor 301 is omitted, a sensor of a type that detects the amount of acceleration generated by camera shake, a subject image is periodically captured as a still image, and the captured still images are compared. A sensor of a type that analyzes how much the subject has moved during the period and outputs an amount of camera shake is common. A detection signal indicating the amount of camera shake is output from the camera shake sensor 301 and input to the control device 1018. The control device 1018 performs the main processing of FIG. 3 described above, and among these, the specific portions as processing in the present embodiment are extracted in FIG.
[0093]
In FIG. 4, steps S401 to S412 are the same as steps S201 to S212 of FIG. 2 in the first embodiment described above, so the description thereof will be omitted and only the processing steps unique to this embodiment will be described. explain.
[0094]
If the value of the counter N becomes equal to or greater than the value of the variable C in step S412 in FIG. 4, it is determined in step S413 whether or not the camera shake amount is smaller than a predetermined value based on the signal from the camera shake sensor 301 in FIG. To do. If the camera shake amount is larger than the predetermined value, it is determined that the subject to be photographed is frequently changed and the drive frequency of the focus lens 1005 is high, and the process proceeds to step S102 in FIG. 1 to stop the focus motor 1011. Control so as not to reduce the holding current. If the camera shake amount is smaller than the predetermined value in step S413, it is determined that the possibility of stopping by focusing is higher than when the camera shake amount is larger than the predetermined value. Then, the process proceeds to step S107 in FIG.
[0095]
By performing the above processing, when the amount of camera shake is larger than a predetermined value and the focus lens is driven frequently as the subject moves due to camera shake, the operation is performed so that it is difficult to shift to the motor holding current reduction operation. Can be controlled.
[0096]
(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIGS. Note that the basic configuration of the imaging apparatus including the lens control device according to the present embodiment is the same as the configuration illustrated in FIGS. 10 and 11 described above, and therefore, both drawings will be used for explanation.
[0097]
FIG. 5 is a flowchart showing a control procedure of processing operations in the control device 1018 in FIG. In this figure, steps S501 to S511 and S513 are the same as steps S201 to S212 in FIG. 2 described above, and therefore only the processing steps unique to this embodiment will be described here.
[0098]
It is a well-known fact that the subject depth increases as the aperture 1003 in FIG. 10 is reduced and the F value of the lens system increases. As the depth of field increases, the focus lens 1005 is more likely to be in focus, and the frequency of stopping the focus lens 1005 is also increased. Actually, the inventor of the present invention measured that the focus lens 1005 is frequently moved when the aperture 1003 is opened, and conversely, the more the aperture 1003 is reduced, the more the subject is photographed. It has been found that the lens 1005 is difficult to move. Accordingly, with respect to the holding current reduction operation after the focus motor 1011 is stopped, the lower the F value, the more difficult it is to shift to the holding current reduction operation, that is, the longer the time to shift to the holding current reduction operation, The system is configured such that this is maintained on the open side where quickness of the waste operation is required, and priority is given to power saving and suppression of heat generation on the small aperture side where the frequency of stopping is high.
[0099]
In FIG. 5, the processing steps for defining the variable C according to the position of the zoom lens 1002 are the same as those in the first embodiment described above.
[0100]
After the variable C is defined in steps S506 to S511 in FIG. 5, the value of the variable C is defined by multiplying the value of the variable C by one or more in accordance with the F value corresponding to the aperture state in step S512. Then, the process proceeds to step S513.
[0101]
The processing in step S512 will be described in detail based on the flowchart of FIG. In steps S601 to S605 in FIG. 6, the state of the diaphragm 1003 is detected from the output signal of the position encoder 1007 in FIG. Multiply the value of by 1 or more. Thereafter, the process proceeds to step S513 in FIG. 5, and the value of the variable C newly set by multiplying by one or more is compared with the value of the counter N. 1, and when the value of the counter N is larger than the value of the variable C, the process proceeds to step S107 in FIG. 1, and when the F value is small and the depth of field is low, That is, the operation can be controlled so that the greater the focus movement is relative to the movement of the subject distance, the more difficult it is to shift to the motor holding current reduction operation.
[0102]
(Fourth embodiment)
Next, a storage medium used in the lens control method and apparatus of the present invention will be described with reference to FIGS.
[0103]
As shown in FIG. 7, the storage medium for storing the control program for controlling the first lens control device for controlling the lens of the lens system having at least one lens according to the present invention includes at least “lens”. It is only necessary to store the program code of each module of “drive module”, “energy amount adjustment module”, “focal length detection module”, “adjustment method change module”, and “adjustment time change module”.
[0104]
Further, as shown in FIG. 8, the storage medium for storing the control program for controlling the second lens control device for controlling the lens of the lens system having at least one lens according to the present invention includes at least “ It is only necessary to store program codes of the modules “lens driving module”, “energy amount adjustment module”, “vibration amount detection module”, “adjustment method change module”, and “adjustment time change module”.
[0105]
Furthermore, as shown in FIG. 9, the storage medium for storing the control program for controlling the third lens control device for controlling the lens of the lens system having at least one lens of the present invention includes at least The program code of each module of “lens driving module”, “energy amount adjustment module”, “aperture value detection module”, “adjustment method change module”, and “adjustment time change module” may be stored.
[0106]
Here, in FIG. 7 described above, the “lens driving module” is a program module for moving the lens. The “energy amount adjusting module” is a program module for adjusting the amount of energy supplied to the lens driving step when the lens is in a stopped state. The “focal length detection module” is a program module for detecting information related to the focal length of the lens system. The “adjustment method change module” is a program module for changing the energy amount adjustment method of the energy amount adjustment step according to the output of the focal length detection step. The “adjustment time change module” is a program module for changing the time for adjusting the amount of energy supplied to the lens driving step according to the output of the focal length detection step when the lens is in a stopped state. .
[0107]
In FIG. 8 described above, the “lens driving module” is a program module for moving the lens. The “energy amount adjusting module” is a program module for adjusting the amount of energy supplied to the lens driving step when the lens is in a stopped state. The “vibration amount detection module” is a program module for detecting the vibration amount of the lens control device. The “adjustment method change module” is a program module for changing the energy amount adjustment method of the energy amount adjustment step according to the output of the focal length detection step. The “adjustment time changing module” is a program module for changing the time for adjusting the amount of energy supplied to the lens driving step according to the output of the focal length detection step when the lens is in a stopped state. .
[0108]
Further, in FIG. 9 described above, the “lens driving module” is a program module for moving the lens. The “energy amount adjusting module” is a program module for adjusting the amount of energy supplied to the lens driving step when the lens is in a stopped state. The “aperture value detection module” is a program module for detecting information related to the aperture value of the lens system. The “adjustment method change module” is a program module for changing the energy amount adjustment method of the energy amount adjustment step according to the output of the focal length detection step. The “adjustment time changing module” is a program module for changing the time for adjusting the amount of energy supplied to the lens driving step according to the output of the focal length detection step when the lens is in a stopped state. .
[0109]
【The invention's effect】
  As described above in detail, the lens control method of the present invention, Lens controlapparatusAnd programsFocusing on the frequency of restarting the focus lens that changes depending on the zoom lens magnification, the higher the frequency, the more difficult it is to shift to the holding current reduction operation, thereby maintaining power saving and heat generation suppression. However, there is an effect that the quickness of the autofocus can be improved.
[0110]
  Also, the lens control method of the present invention, Lens controlapparatusAnd programsAccording to the above, it is noted that the more the camera shake is, the more frequently the focus lens is restarted. When there is a lot of camera shake, it is difficult to shift to the holding current reduction operation, thereby reducing power consumption and heat generation. There is an effect that the quickness of the autofocus can be improved while maintaining the suppression.
[0111]
  Also, the lens control method of the present invention, Lens controlapparatusAnd programsAccording to the above, it is noted that the lower the depth of field of the lens, the higher the frequency of restarting the focus lens, and when the depth is low, the shift to the holding current reduction operation is difficult. There is an effect that the speed of autofocus can be improved while maintaining the suppression of electric power and heat generation.
[0112]
Furthermore, according to the storage medium of the present invention, it is possible to smoothly control the lens control device of the present invention.
[Brief description of the drawings]
FIG. 1 is a flowchart showing an operation control procedure in a control device of a lens control device according to a first embodiment of the present invention.
FIG. 2 is a flowchart showing a detailed control procedure of processing in step S105 in FIG.
FIG. 3 is a block diagram illustrating a configuration of an imaging apparatus including a lens control device according to a second embodiment of the present invention.
FIG. 4 is a flowchart similar to FIG. 2 in the same apparatus.
FIG. 5 is a flowchart similar to FIG. 2 in the lens control device according to the second embodiment of the present invention;
FIG. 6 is a flowchart showing a detailed control procedure of the process of step 512 in FIG. 5;
FIG. 7 is a diagram showing program modules stored in the storage medium of the present invention. .
FIG. 8 is a diagram showing program modules stored in the storage medium of the present invention.
FIG. 9 is a diagram showing program modules stored in the storage medium of the present invention.
FIG. 10 is a block diagram illustrating a configuration of an imaging apparatus including a conventional lens control device.
FIG. 11 is a cross-sectional view showing a configuration of a drive portion of the focus lens in the apparatus.
FIG. 12 is a diagram showing a cam trajectory of a rear focus lens system in the apparatus.
FIG. 13 is a view for explaining a stepping motor driving method in the apparatus;
FIG. 14 is a view showing a state of rotation of a rotor of a stepping motor in the apparatus.
FIG. 15 is a flowchart showing a control procedure of operations in the control device of the apparatus.
FIG. 16 is a view for explaining motor runout immediately after stopping in the apparatus;
FIG. 17 is a diagram showing how the motor is energized in the apparatus.
FIG. 18 is a block diagram showing a configuration of a motor driver in the apparatus.
FIG. 19 is a flowchart showing a control procedure of a switch control operation in the apparatus.
FIG. 20 is a block diagram showing a configuration of a current amount suppression circuit in the same device.
FIG. 21 is a flowchart showing an operation control procedure in the switch control circuit in the apparatus.
FIG. 22 is a block diagram showing a configuration of a drive control circuit for outputting an excitation pattern to the motor driver in the same device.
FIG. 23 is a flowchart showing a control procedure of a holding current reduction operation in a conventional lens control device.
[Explanation of symbols]
1001 First lens group
1002 Second lens group (zoom lens)
1003 Aperture
1004 Third lens group
1005 Fourth lens group
1006 Position converter
1007 Position converter
1008 Position converter
1009 Zoom motor
1010 Iris motor
1011 Focus motor
1012 Zoom motor driver
1013 Iris motor driver
1014 Focus motor driver
1015 Image sensor
1016 amplifier
1017 Bandpass filter
1018 Controller
1019 Aperture control device
1101 Output shaft
1102 Holding member
1103 Bearing
1104 Guide bar
1105 rack
301 Camera shake sensor

Claims (12)

A lens control method for holding the lens in a predetermined position by supplying a holding current to a lens driving means for driving the lens,
A holding current supplying step of supplying a holding current to the lens driving unit for a predetermined time when the lens driving unit stops driving the lens;
A supply current limiting step for limiting the supply of the holding current after supplying the holding current to the lens driving unit for the predetermined time;
And wherein the focal length of the lens in the case of the first focal length, and a switching step to lengthen the predetermined time compared to the case of the shorter than the first focal length second focal length To control the lens.   The lens control method according to claim 1, wherein the first and second focal lengths are adjusted by a zoom lens capable of zooming. A lens control method for holding the lens in a predetermined position by supplying a holding current to a lens driving means for driving the lens,
A holding current supplying step of supplying a holding current to the lens driving unit for a predetermined time when the lens driving unit stops driving the lens;
A supply current limiting step for limiting the supply of the holding current after supplying the holding current to the lens driving unit for the predetermined time;
In case of the vibration amounts first vibration of the lens, and characterized in that it has a switching step to lengthen the predetermined time compared to the case of the first vibration amount smaller second vibration amount than To control the lens. A lens control method for holding the lens in a predetermined position by supplying a holding current to a lens driving means for driving the lens,
A holding current supplying step of supplying a holding current to the lens driving unit for a predetermined time when the lens driving unit stops driving the lens;
A supply current limiting step for limiting the supply of the holding current after supplying the holding current to the lens driving unit for the predetermined time;
In case of aperture value first aperture value of the aperture mechanism for adjusting the amount of light passing through the lens, to increase the predetermined time compared to the case of the first second aperture larger than the aperture value And a switching step . The lens control method according to claim 1, wherein the lens is driven using a stepping motor . A lens control device for holding the lens in a predetermined position by supplying a holding current to a lens driving means for driving the lens;
Holding current supply means for supplying a holding current to the lens driving means for a predetermined time when the lens driving means stops driving the lens;
Supply current limiting means for limiting supply of the holding current after supplying the holding current to the lens driving means for the predetermined time;
And wherein the focal length of the lens in the case of the first focal length, and a switching means to prolong said predetermined period of time as compared with the case of the shorter than the first focal length second focal length Lens control device. A lens control device for holding the lens in a predetermined position by supplying a holding current to a lens driving means for driving the lens;
Holding current supply means for supplying a holding current to the lens driving means for a predetermined time when the lens driving means stops driving the lens;
Supply current limiting means for limiting supply of the holding current after supplying the holding current to the lens driving means for the predetermined time;
And wherein the vibration of the lens is the case of the first vibration amount, and a switching means to prolong said predetermined period of time as compared with the case of the first vibration amount smaller second vibration amount than Lens control device. A lens control device for holding the lens in a predetermined position by supplying a holding current to a lens driving means for driving the lens;
Holding current supply means for supplying a holding current to the lens driving means for a predetermined time when the lens driving means stops driving the lens;
Supply current limiting means for limiting supply of the holding current after supplying the holding current to the lens driving means for the predetermined time;
In case of aperture value first aperture value of the aperture mechanism for adjusting the amount of light passing through the lens, to increase the predetermined time compared to the case of the first second aperture larger than the aperture value And a switching unit . A program for causing a computer to execute a lens control method for holding the lens in a predetermined position by supplying a holding current to a lens driving unit that drives the lens,
A holding current supply module that supplies a holding current to the lens driving unit for a predetermined time when the lens driving unit stops driving the lens;
A supply current limiting module for limiting the supply of the holding current after supplying the holding current to the lens driving unit for the predetermined time;
The focal length if the first focal length of the lens, thereby executing the switching module to increase the predetermined time compared to the case of the shorter than the first focal length second focal length to the computer A program characterized by A program for causing a computer to execute a lens control method for holding the lens in a predetermined position by supplying a holding current to a lens driving unit that drives the lens,
A holding current supply module that supplies a holding current to the lens driving unit for a predetermined time when the lens driving unit stops driving the lens;
A supply current limiting module for limiting the supply of the holding current after supplying the holding current to the lens driving unit for the predetermined time;
In case of the vibration amounts first vibration of the lens, thereby executing the switching module to increase the predetermined time compared to the case of the first vibration amount smaller second vibration amount than the computer A program characterized by A program for causing a computer to execute a lens control method for holding the lens in a predetermined position by supplying a holding current to a lens driving unit that drives the lens,
A holding current supply module that supplies a holding current to the lens driving unit for a predetermined time when the lens driving unit stops driving the lens;
A supply current limiting module for limiting the supply of the holding current after supplying the holding current to the lens driving unit for the predetermined time;
In case of aperture value first aperture value of the aperture mechanism for adjusting the amount of light passing through the lens, to increase the predetermined time compared to the case of the first second aperture larger than the aperture value A program for causing a computer to execute a switching module .   A storage medium storing the program according to any one of claims 9 to 11.

Images