JP2013011732A - Optical instrument and control method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid deviation of an optical element (step-out of a stepping motor) when subjected to impact or vibration while preventing increase in power consumption.SOLUTION: An optical instrument includes a movable optical element 3; a stepping motor 9 that moves the optical element; control means 13, 11 that controls driving of the stepping motor; and acceleration detecting means 15 that detects acceleration acting in a movable direction of the optical element with respect to the optical instrument. In a state in which the stepping motor is not moving the optical element, the control means controls excitation voltage applied to the stepping motor for keeping the position of the optical element in response to the acceleration detected by the acceleration detecting means.

Description

  The present invention relates to an imaging apparatus having an optical element such as a lens moved by a stepping motor, and an optical apparatus such as an interchangeable lens.

  If a strong impact or vibration is applied to the optical device by dropping the optical device as described above or colliding with a peripheral object, the optical element moves in its movable direction even though the stepping motor is not driven. Displace. As a result, an error occurs between the position of the optical element recognized by a controller (CPU or the like) provided in the optical apparatus and the actual position of the optical element. That is, the stepping motor is stepped out. This step-out makes it impossible to control the position of the optical element with high accuracy.

  In Patent Document 1, the driving torque of the stepping motor is changed according to the posture of the optical device when the optical element is moved by driving the stepping motor, that is, the relationship between the direction in which gravity acts and the moving direction of the optical element. An optical apparatus configured to do so is disclosed.

JP 2009-237530 A

  In the optical apparatus disclosed in Patent Document 1, the optical element can be stably moved by the stepping motor regardless of the posture.

  However, not only when the optical element is moved by the stepping motor but also when the optical element is not moved by the stepping motor, it is necessary to avoid the occurrence of the stepping motor step-out due to the impact or vibration described above. Although a high excitation voltage can be applied to the stepping motor so as to stop the rotation of the stepping motor even when a certain degree of impact is received, the power consumption increases.

  The present invention provides an optical device capable of avoiding displacement of an optical element (stepping motor step-out) when subjected to an impact or vibration while suppressing an increase in power consumption.

  An optical apparatus according to one aspect of the present invention includes a movable optical element, a stepping motor that moves the optical element, a control unit that controls driving of the stepping motor, and a movement of the optical element relative to the optical apparatus. Acceleration detecting means for detecting acceleration acting in a possible direction. The control means controls the excitation voltage applied to the stepping motor in order to hold the position of the optical element in accordance with the acceleration detected by the acceleration detection means in a state where the stepping motor does not move the optical element. It is characterized by that.

  An optical apparatus according to another aspect of the present invention includes a movable optical element, a stepping motor that moves the optical element, a control unit that controls driving of the stepping motor, and an optical element for the optical apparatus. Acceleration detecting means for detecting acceleration acting in the movable direction. The control means drives the stepping motor so as to move the optical element in the direction of the acceleration when the acceleration detecting means detects the acceleration in a state where the stepping motor does not move the optical element. Features.

  An optical apparatus according to another aspect of the present invention includes a movable optical element, a stepping motor that moves the optical element, a control unit that controls driving of the stepping motor, and an optical element for the optical apparatus. Acceleration detecting means for detecting acceleration acting in the movable direction. The control means drives the stepping motor to move the optical element to a reference position for detecting the position of the optical element in response to the acceleration detected by the acceleration detecting means.

  An optical apparatus according to another aspect of the present invention includes a movable optical element, a stepping motor that moves the optical element, a control unit that controls driving of the stepping motor, and an optical element for the optical apparatus. Acceleration detecting means for detecting acceleration acting in the movable direction. The control means holds the position of the optical element according to the acceleration when the acceleration detected by the acceleration detection means is smaller than the first predetermined value when the optical element is not moved by the stepping motor. In order to achieve this, the excitation voltage applied to the stepping motor is controlled. Further, when the acceleration is larger than the first predetermined value and smaller than the second predetermined value when the stepping motor does not move the optical element, the control means moves the optical element in the acting direction of the acceleration. The stepping motor is driven so that the Further, the control means drives the stepping motor to move the optical element to a reference position for detecting the position of the optical element when the acceleration is larger than the second predetermined value.

  A control method according to another aspect of the present invention is applied to an optical apparatus having a movable optical element and a stepping motor that moves the optical element. The control method includes a step of detecting an acceleration acting on the optical device in a movable direction of the optical element, and an optical element according to the detected acceleration in a state where the stepping motor does not move the optical element. And a step of controlling an excitation voltage applied to the stepping motor in order to maintain the position.

  The control method according to another aspect of the present invention is applied to an optical apparatus having a movable optical element and a stepping motor that moves the optical element. The control method includes a step of detecting an acceleration acting on the optical device in a movable direction of the optical element, and an action of the acceleration when the acceleration is detected in a state where the stepping motor does not move the optical element. And driving the stepping motor to move the optical element in the direction.

  The control method according to another aspect of the present invention is applied to an optical apparatus having a movable optical element and a stepping motor that moves the optical element. The control method includes a step of detecting an acceleration acting on the optical device in a movable direction of the optical element, and a reference for detecting the position of the optical element according to the detection of the acceleration. And a step of driving the stepping motor so as to be moved to the position.

  The control method according to another aspect of the present invention is applied to an optical apparatus having a movable optical element and a stepping motor that moves the optical element. The control method includes a step of detecting an acceleration acting on the optical device in a movable direction of the optical element, and an acceleration detected by the acceleration detecting means in a state in which the optical element is not moved by the stepping motor. If less than a predetermined value of 1, the step of controlling the excitation voltage applied to the stepping motor to maintain the position of the optical element according to the acceleration, and the stepping motor is not moving the optical element, When the acceleration is larger than the first predetermined value and smaller than the second predetermined value, the stepping motor is driven to move the optical element in the acting direction of the acceleration, and the acceleration is lower than the second predetermined value. If larger, drive the stepping motor to move the optical element to the reference position for detecting the position of the optical element. Characterized by a step.

According to the present invention, the excitation voltage for stopping and holding the stepping motor is controlled in accordance with the acceleration (impact and vibration strength) applied to the optical device, or the optical element is moved in the direction of the acceleration in the stepping motor. Or reset processing to the reference position. Therefore, compared with the case where a constant high excitation voltage is always applied to the stepping motor and this is stopped and held, the increase in power consumption is suppressed and the stepping motor is stepped out and the optical element position is controlled accordingly. A decrease in accuracy can be avoided.

1 is a block diagram illustrating a configuration of a digital camera that is Embodiment 1 of the present invention. FIG. 3 is a diagram illustrating an acceleration detection direction of an acceleration sensor in the digital camera according to the first embodiment. 3 is a flowchart showing processing performed in the digital camera of Embodiment 1. 9 is a flowchart illustrating processing performed in a digital camera that is Embodiment 2 of the present invention. The figure which shows the relationship between the acceleration in Example 1, 2 and the control method of a stepping motor. 9 is a flowchart showing processing performed in a digital camera that is Embodiment 3 of the present invention. 9 is a flowchart showing processing performed in a digital camera that is Embodiment 4 of the present invention. FIG. 10 is a diagram illustrating a display example of an LCD for notifying photographing prohibition during a reset operation in the third and fourth embodiments.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows the configuration of a digital camera (hereinafter simply referred to as a camera) as an optical apparatus that is Embodiment 1 of the present invention. Reference numeral 1 denotes a lens barrel of the camera. The lens barrel 1 accommodates a zoom lens 2 for zooming, a focus lens 3 having a compensator function and a focusing function, and a photographing optical system including other lenses and a diaphragm (not shown). In the lens barrel 1, the variable power lens 2 and the focus lens 3 are held by a guide bar (not shown) so as to be movable in the optical axis direction. The variable power lens 2 and the focus lens 3 include a rack member (not shown), and the rack member meshes with a lead screw (not shown) rotated by the zoom motor 8 and the focus motor 9 in the optical axis direction. Moved.

  The light from the subject that has passed through the photographing optical system forms a subject image on the imaging surface of the imaging element 4 constituted by a CCD sensor or a CMOS sensor. The image sensor 4 photoelectrically converts the subject image and outputs an analog image signal. The imaging signal processing unit 5 performs A / D conversion and amplification on the analog imaging signal read from the imaging element 4 and outputs a digital imaging signal to the video signal processing unit 6. The video signal processing unit 6 performs various types of signal processing on the digital imaging signal to generate a video signal. The video signal is displayed on an LCD (Liquid Crystal Display) 7 as an electronic viewfinder, or is recorded on a recording medium such as a semiconductor memory (not shown) via the system controller 13.

  In addition to the video signal generated from the imaging signal, various menus and messages for the user are displayed on the LCD 7.

  Further, the system controller 13 controls the charge accumulation time (shutter speed) in the image pickup device 4 via the image pickup signal processing unit 5 according to the luminance level of the video signal, and adjusts the luminance of the video signal.

  Further, an operation unit 14 is connected to the system controller 13. The operation unit 14 is provided with operation members such as buttons, levers, and dials. The operation unit 14 sends operation signals corresponding to ON / OFF operations, lever operation amounts, and dial rotation amounts of these operation members to the system controller 13. Output to. The system controller 13 performs operations and processes such as power ON / OFF, start of shooting, zooming, and shooting mode switching in accordance with the operation signal.

  The zoom control unit 10 and the focus control unit 11 respectively control the driving (including stop holding) of the zoom motor 8 and the focus motor 9 in accordance with commands from the system controller 13. Specifically, the system controller 13 sends a drive / stop command, a drive direction command, and a drive speed command for the zoom motor 8 to the zoom control unit 10 in accordance with an operation signal related to zooming from the operation unit 14. Further, the system controller 13 sends a drive / stop command, a drive direction command, and a drive speed command for the focus motor 9 to the focus control unit 11 based on a calculation result related to AF (autofocus) in the system controller 13.

  In this embodiment, a DC motor is used as the zoom motor 8 and a stepping motor is used as the focus motor 9. Therefore, the zoom control unit 10 and the focus control unit 11 control the excitation voltage applied to the zoom motor 8 and the focus motor 9, respectively. The system controller 13, the zoom control unit 10, and the focus control unit 11 constitute a control means.

  A focus motor 9 that is a stepping motor includes a plurality of electromagnets (stators) arranged in a circumferential direction in a motor case, and permanent magnets (inside the stator, alternately having N and S poles in the circumferential direction). (Rotor) and an output shaft that rotates integrally with the rotor. When a current is sequentially passed through the coils of the plurality of stators (that is, an excitation voltage is applied), a magnetic force is generated in the energized stator. The rotor is attracted or repelled by the magnetic force, and the output shaft rotates together with the rotor. By changing the position and the number of stators to which the excitation voltage is applied, it is possible to increase the rotational torque of the rotor and the output shaft (hereinafter collectively referred to as the rotor) or to stop and maintain it. Moreover, the magnetic force generated in the stator can be changed by changing the excitation voltage, and the rotational torque and the stop holding force can be increased or decreased. In the following description, the excitation voltage applied to stop and hold the rotor is referred to as a holding excitation voltage.

  As shown in FIG. 1, a photo interrupter (PI) 12 for detecting that the focus lens 3 is located at a reference position for detecting the position of the focus lens 3 is disposed in the lens barrel 1. The photo interrupter 12 includes a light emitting element such as a photodiode and a light receiving element such as a phototransistor. Since a light shielding portion provided in a holding frame (not shown) that holds the focus lens 3 enters between the light emitting element and the light receiving element, the incidence of light from the light emitting element to the light receiving element is blocked, and the focus lens It is detected that 3 is located at the reference position. The system controller 13 resets the internal position counter by detecting the reference position of the focus lens 3. This process is called a reset process, and is performed at a predetermined timing such as when the power is turned on.

  Then, the system controller 13 counts a signal output from a position detector such as an encoder (not shown) every time the focus lens 3 is moved after the reset process, thereby detecting the position and controlling the position of the focus lens 3. I do. A similar reset process is performed for the variable magnification lens 2.

  Further, the system controller 13 is connected with an acceleration sensor (acceleration detection means) 15 for detecting acceleration acting on the camera due to impact or vibration. The acceleration sensor 15 in the present embodiment is a capacitance type acceleration sensor, and as shown in FIG. 2A, in the three-axis directions of the X axis, the Y axis, and the Z axis that are orthogonal to each other in a three-dimensional space. Can be detected respectively. The Z axis is an axis extending in parallel with the optical axis of the photographing optical system with the direction toward the subject being positive, and the X axis is an axis extending in the horizontal direction with the right direction when viewed from the back as a positive. The Y axis is an axis extending in the vertical direction with the upper direction being positive.

  Note that acceleration is also caused by so-called camera shake when taking a picture with the camera held in hand. However, the acceleration sensor 15 in this embodiment is not an acceleration due to a shake with a long period due to hand shake and a small amplitude but a level with a large amplitude in a short period due to a strong impact or vibration that causes a step out of the stepping motor. Detect acceleration due to shake.

  The system controller 13 uses the acceleration detected by the acceleration sensor 15 to perform arithmetic processing based on an arithmetic expression stored in a memory (not shown), and determines a command for the focus control unit 11.

  FIG. 2B shows the relationship between the lens barrel 1 and the acting direction of acceleration, which is a particular problem in this embodiment. Since the axis extending parallel to the optical axis is the Z-axis, the acceleration in the Z-axis direction is an acceleration acting on the focus lens 3 so as to be displaced in the movable direction of the focus lens 3 by an impact or vibration applied to the camera. It becomes a problem. Therefore, in the following description, acceleration means acceleration in the Z-axis direction.

  Next, processing performed by the camera of this embodiment will be described with reference to the flowchart of FIG. This process is executed by the system controller 13 according to the computer program.

  First, in step S301, the system controller 13 determines whether or not a power-on operation has been performed on the operation unit 14, and if a power-on operation has been performed, the process proceeds to step S302. If the power ON operation has not been performed, step S301 is repeated.

  In step S302, the system controller 13 performs activation processing including initialization of control variables and the like. In addition, reset processing of the positions of the zoom lens 2 and the focus lens 3 is performed.

  Next, in step S303, the system controller 13 stops holding the rotor of the focus motor 9 so that the focus lens 3 is not displaced in the movable direction, so that the holding excitation voltage is applied to the focus motor 9 via the focus control unit 11. Apply. The magnitude of the holding excitation voltage applied here is determined based on the weight of the focus lens 3 and the moving load, which will be described in detail later.

  Next, in step S304, the system controller 13 determines whether or not a power OFF operation has been performed using the operation unit 14, and if a power OFF operation has been performed, the system controller 13 proceeds to step S305. If the power OFF operation has not been performed, the process proceeds to step S306.

  In step S305, the system controller 13 drives the zoom motor 8 and the focus motor 9 via the zoom control unit 10 and the focus control unit 11, and moves the zoom lens 2 and the focus lens 3 to a predetermined storage position. Thereafter, a power shutdown process is performed.

  In step S306, the system controller 13 acquires the current acceleration (acceleration in the Z-axis direction) from the acceleration sensor 15.

  In step S307, the system controller 13 determines whether the acceleration acquired in step S306 is smaller than a predetermined value. If it is smaller than the predetermined value, the process proceeds to step S309. If it is equal to or larger than the predetermined value (or larger than the predetermined value), the process proceeds to step S308. The predetermined value here is determined as a threshold value that can cause the focus motor 9 to step out based on the weight, movement characteristics, and the like of the focus lens 3, and is stored in advance in a memory (not shown) as data.

  In step S308, the system controller 13 applies a holding excitation voltage that varies depending on the magnitude of the acceleration to the focus motor 9 so that the focus motor 9 does not step out due to an acceleration of a predetermined value or more and the focus lens 3 is not displaced. When the process of step S308 ends, the system controller 13 proceeds to step S309.

  FIG. 5A shows the relationship between the magnitude of acceleration and the holding excitation voltage in steps S303 and S308. When the acceleration is smaller than the predetermined value, the holding excitation voltage is set to a fixed value in step S303. That is, the holding excitation voltage is fixedly controlled. On the other hand, when the acceleration is equal to or greater than the predetermined value (greater than the predetermined value), the holding excitation voltage is increased (proportionally higher) in step S308 as the acceleration increases in the voltage range higher than the fixed value. To be changed). That is, variable control of the holding excitation voltage is performed.

  The holding excitation voltage to be applied can be calculated by substituting the detected acceleration into an arithmetic expression indicating the relationship between the acceleration and the holding excitation voltage shown in FIG. In addition, a plurality of holding excitation voltages corresponding to each of a plurality of accelerations are stored in the memory as table data in advance, and the holding excitation voltage corresponding to the acceleration detected from the table data or an acceleration close thereto is read out. May be. At this time, the holding excitation voltage to be applied may be determined by an interpolation calculation using two holding excitation voltages corresponding to two accelerations close to the detected acceleration.

  Thus, in this embodiment, when the focus motor 9 does not move the focus lens 3 and detects acceleration due to impact or vibration, the holding excitation voltage for holding the position of the focus lens 3 is used as the acceleration. Control according to. In particular, when the acceleration is greater than or equal to a predetermined value (greater than the predetermined value), the holding excitation voltage is changed so as to increase as the acceleration increases. Thereby, the step-out of the focus motor 9 and the displacement of the focus lens 3 associated therewith can be prevented regardless of the magnitude of acceleration, that is, the magnitude of impact or vibration. In addition, by changing the holding excitation voltage according to the acceleration, it is possible to reduce the power consumption compared to the case where the high holding excitation voltage corresponding to the large acceleration is continuously applied.

  In step S309, the system controller 13 determines whether or not a shooting start operation has been performed using the operation unit 14, and if a shooting start operation has been performed, the process proceeds to step S310. If the shooting start operation has not been performed, the process returns to step S304.

  In step S310, the system controller 13 performs a photographing process. In this photographing process, automatic exposure (AE) control and AF control are performed, and a photographed image is generated from an imaging signal obtained by photoelectrically converting a subject image by the image sensor 4.

  As described above, according to the present embodiment, it is possible to prevent the focus motor 9 from stepping out and the accompanying displacement of the focus lens 3 while suppressing an increase in power consumption.

  The flowchart of FIG. 4 shows processing performed by the digital camera that is Embodiment 2 of the present invention. The configuration of the camera of the present embodiment is the same as that of the first embodiment, and the same reference numerals as those of the first embodiment are assigned to components common to the first embodiment. The process shown in FIG. 4 is executed by the system controller 13 according to the computer program.

  First, in step S401, the system controller 13 determines whether or not a power-on operation has been performed on the operation unit 14, and if a power-on operation has been performed, the process proceeds to step S402. If the power ON operation has not been performed, step S401 is repeated.

  In step S402, the system controller 13 performs activation processing including initialization of control variables. In addition, reset processing of the positions of the zoom lens 2 and the focus lens 3 is performed.

  Next, in step S403, the system controller 13 applies a holding excitation voltage to the focus motor 9 in order to stop and hold the rotor of the focus motor 9 so that the focus lens 3 is not displaced in the movable direction. The magnitude of the holding excitation voltage applied here is determined based on the weight of the focus lens 3 and the moving load as in the first embodiment, and is a fixed value shown in FIG.

  Next, in step S404, the system controller 13 determines whether or not a power OFF operation has been performed on the operation unit 14, and if a power OFF operation has been performed, the system controller 13 proceeds to step S405. If the power OFF operation has not been performed, the process proceeds to step S406.

  In step S405, the system controller 13 drives the zoom motor 8 and the focus motor 9 to move the zoom lens 2 and the focus lens 3 to a predetermined storage position. Thereafter, a power shutdown process is performed.

  In step S406, the system controller 13 acquires the current acceleration (acceleration in the Z-axis direction) from the acceleration sensor 15.

  In step S407, the system controller 13 determines whether the acceleration acquired in step S406 is smaller than a predetermined value. If it is smaller than the predetermined value, the process proceeds to step S408. If it is equal to or larger than the predetermined value (or larger than the predetermined value), the process proceeds to step S410. The predetermined value here is determined as a threshold value that can cause the focus motor 9 to step out based on the weight, movement characteristics, and the like of the focus lens 3, and is stored in advance in a memory (not shown) as data.

  In step S <b> 408, the system controller 13 determines whether or not the focus lens 3 is moved in the direction of the acceleration, that is, in the optical axis direction (Z-axis direction) by driving the focus motor 9. If the focus lens 3 has been moved in the direction of the acceleration, the process proceeds to step S409, and if not, the process proceeds to step S411.

  In step S409, the system controller 13 stops driving the focus motor 9 (movement of the focus lens 3). At this time, the system controller 13 applies a holding excitation voltage having a fixed value shown in FIG. 5A to the focus motor 9 in order to hold the position of the focus lens 3 where the movement is interrupted. Then, the process proceeds to step S411.

  On the other hand, in step S410, the system controller 13 drives the focus motor 9 to move the focus lens 3 so that the focus motor 9 does not step out due to an acceleration of a predetermined value or more and the focus lens 3 is not displaced to an unexpected position. Move in the direction of acceleration action. That is, when the focus motor 9 detects an acceleration greater than (or greater than) a predetermined value in a state where the focus lens 3 is not moved, the focus motor 9 is moved so that the focus lens 3 is moved in the acting direction of the acceleration. To drive.

  FIG. 5B shows the relationship between the magnitude of acceleration and the driving speed of the focus motor 9 in steps S409 and S410. When the acceleration is smaller than the predetermined value, the drive of the focus motor 9 is stopped in step S409, and the holding excitation voltage is applied to the focus motor 9. On the other hand, when the acceleration is equal to or greater than the predetermined value (greater than the predetermined value), in step S410, the driving speed of the focus motor 9 (the moving speed of the focus lens 3) is increased as the acceleration increases (proportional). To be faster).

  The driving speed of the focus motor 9 can be calculated by substituting the detected acceleration into an arithmetic expression showing the relationship between the acceleration and the driving speed shown in FIG. Further, a plurality of driving speeds corresponding to each of the plurality of accelerations are stored in advance in a memory as table data, and determined by reading the driving speed corresponding to the acceleration detected from the table data or acceleration close thereto. Also good. At this time, the drive speed may be determined by an interpolation calculation using two drive speeds corresponding to two accelerations close to the detected acceleration.

  As described above, in this embodiment, when the focus motor 9 does not move the focus lens 3 and the acceleration of a predetermined value or more due to impact or vibration is detected, the focus lens 3 is moved in the direction in which the acceleration is applied. The focus motor 9 is driven so that the In particular, the drive speed (that is, the excitation voltage) of the focus motor 9 is changed so that the moving speed of the focus lens 3 increases as the acceleration increases. Thereby, regardless of the magnitude of acceleration, that is, the magnitude of impact or vibration, it is possible to prevent the step-out of the focus motor 9 and the accompanying displacement of the focus lens 3 to an unexpected position. In addition, by changing the excitation voltage according to the acceleration, it is possible to reduce power consumption compared to the case where a high excitation voltage corresponding to a large acceleration is continuously applied.

  In step S411, the system controller 13 determines whether or not a shooting start operation has been performed using the operation unit 14, and if a shooting start operation has been performed, the process proceeds to step S412. If the shooting start operation has not been performed, the process returns to step S404.

  In step S412, the system controller 13 performs a photographing process. In this photographing process, automatic exposure (AE) control and AF control are performed, and a photographed image is generated from an imaging signal obtained by photoelectrically converting a subject image by the image sensor 4.

  As described above, according to the present embodiment, it is possible to prevent the focus motor 9 from stepping out and accompanying displacement of the focus lens 3 to an unexpected position while suppressing an increase in power consumption.

The flowchart of FIG. 6 shows processing performed by the digital camera that is Embodiment 3 of the present invention. The configuration of the camera of the present embodiment is the same as that of the first embodiment, and the same reference numerals as those of the first embodiment are assigned to components common to the first embodiment. The process shown in FIG. 6 is executed by the system controller 13 according to the computer program.

  First, in step S501, the system controller 13 determines whether or not a power ON operation has been performed using the operation unit 14, and if a power ON operation has been performed, the system controller 13 proceeds to step S502. If the power ON operation has not been performed, step S501 is repeated.

  In step S502, the system controller 13 performs activation processing including initialization of control variables. In addition, reset processing of the positions of the zoom lens 2 and the focus lens 3 is performed.

  Next, in step S503, the system controller 13 applies a holding excitation voltage to the focus motor 9 in order to stop and hold the rotor of the focus motor 9 so that the focus lens 3 is not displaced in the movable direction. The magnitude of the holding excitation voltage applied here is determined based on the weight of the focus lens 3 and the moving load as in the first embodiment, and is a fixed value shown in FIG.

  Next, in step S504, the system controller 13 determines whether or not a power OFF operation has been performed using the operation unit 14, and if a power OFF operation has been performed, the process proceeds to step S505. If the power OFF operation has not been performed, the process proceeds to step S506.

  In step S505, the system controller 13 drives the zoom motor 8 and the focus motor 9 to move the zoom lens 2 and the focus lens 3 to a predetermined storage position. Thereafter, a power shutdown process is performed.

  In step S506, the system controller 13 acquires the current acceleration (acceleration in the Z-axis direction) from the acceleration sensor 15.

  In step S507, the system controller 13 determines whether the acceleration acquired in step S506 is smaller than a predetermined value. If it is smaller than the predetermined value, the process proceeds to step S513. If it is equal to or larger than the predetermined value (or larger than the predetermined value), the process proceeds to step S508. The predetermined value here is determined as a threshold value that can cause the focus motor 9 to step out based on the weight, movement characteristics, and the like of the focus lens 3, and is stored in advance in a memory (not shown) as data.

  In step S508, the system controller 13 considers that there is a high possibility that the focus motor 9 has stepped out due to an acceleration greater than or equal to a predetermined value, and accurate position control of the focus lens 3 cannot be performed, and performs processing for prohibiting shooting. . In other words, a process for prohibiting the use of the camera is performed. Specifically, as the photographing prohibition process, the system controller 13 displays a message indicating that photographing cannot be performed on the LCD 7 as shown in FIG. Further, even if an operation for starting photographing is performed by the operation unit 14, this is invalidated.

  Next, in step S509, the system controller 13 obtains the current acceleration (acceleration in the Z-axis direction) from the acceleration sensor 15 again.

  In step S510, the system controller 13 determines whether the magnitude of the acceleration acquired in step S509 is smaller than a predetermined value. If it is smaller than the predetermined value, the process proceeds to step S511, and if it is equal to or larger than the predetermined value (or larger than the predetermined value), the process returns to step S509 to repeat the acquisition of acceleration. The predetermined value in this step is basically the same as the predetermined value in step S506, but may be smaller than the predetermined value.

  In step S511, the system controller 13 drives the focus motor 9 via the focus control unit 11, and performs a reset process of the focus lens 3. That is, if the magnitude of the acceleration acquired in step S509 is greater than or equal to a predetermined value, the focus lens 3 is reset after the acceleration is smaller than the predetermined value. When this reset process is completed, in step S512, the system controller 13 cancels the photographing prohibition. Thereafter, the process returns to step S504.

  Even when the focus motor 9 steps out due to the acceleration generated by the impact or vibration applied to the camera, and the accurate position control of the focus lens 3 cannot be performed, the accurate position control of the focus lens 3 is performed by performing the reset process. Can be resumed.

  Further, until the reset process is completed, the focus lens 3 that cannot perform accurate position control causes a defocusing to prevent photographing, thereby preventing the generation of a defocused photographed image. it can.

  In step S513, the system controller 13 determines whether or not a shooting start operation has been performed using the operation unit 14, and if a shooting start operation has been performed, the process proceeds to step S514. If the shooting start operation has not been performed, the process returns to step S504.

  In step S514, the system controller 13 performs a shooting process. In this photographing process, automatic exposure (AE) control and AF control are performed, and a photographed image is generated from an imaging signal obtained by photoelectrically converting a subject image by the image sensor 4.

  As described above, according to the present embodiment, it is possible to perform normal position control of the focus lens 3 even when the camera receives an impact or vibration.

  The flowchart of FIG. 7 shows processing performed by the digital camera that is Embodiment 3 of the present invention. The configuration of the camera of the present embodiment is the same as that of the first embodiment, and the same reference numerals as those of the first embodiment are assigned to components common to the first embodiment. The process shown in FIG. 6 is executed by the system controller 13 according to the computer program.

  First, in step S701, the system controller 13 determines whether or not a power ON operation has been performed by the operation unit 14, and if a power ON operation has been performed, the process proceeds to step S702. If the power ON operation has not been performed, step S701 is repeated.

  In step S702, the system controller 13 performs a startup process including initialization of control variables. In addition, reset processing of the positions of the zoom lens 2 and the focus lens 3 is performed.

  Next, in step S703, the system controller 13 applies a holding excitation voltage to the focus motor 9 in order to stop and hold the rotor of the focus motor 9 so that the focus lens 3 is not displaced in the movable direction. The magnitude of the holding excitation voltage applied here is determined based on the weight of the focus lens 3 and the moving load as in the first embodiment, and is a fixed value shown in FIG.

  Next, in step S704, the system controller 13 determines whether or not a power OFF operation has been performed using the operation unit 14, and if a power OFF operation has been performed, the process proceeds to step S705. If the power OFF operation has not been performed, the process proceeds to step S706.

  In step S705, the system controller 13 drives the zoom motor 8 and the focus motor 9 to move the zoom lens 2 and the focus lens 3 to a predetermined storage position. Thereafter, a power shutdown process is performed.

  In step S <b> 706, the system controller 13 acquires the current acceleration (acceleration in the Z-axis direction) from the acceleration sensor 15.

  In step S707, the system controller 13 determines whether the acceleration acquired in step S706 is smaller than a predetermined value A. If it is smaller than the predetermined value A, the process proceeds to step S719, and if it is greater than or equal to the predetermined value A (or larger than the predetermined value A), the process proceeds to step S708. The predetermined value A here is determined as a threshold value that may cause the focus motor 9 to step out based on the weight and movement characteristics of the focus lens 3, and is stored in advance in a memory (not shown) as data.

  In step S708, the system controller 13 determines whether or not the magnitude of acceleration equal to or greater than the predetermined value A acquired in step S706 is smaller than a predetermined value B (first predetermined value) set larger than the predetermined value A. judge. If it is smaller than the predetermined value B, the process proceeds to step S709. If it is equal to or larger than the predetermined value B (or larger than the predetermined value B), the process proceeds to step S712. The predetermined value B here is determined on the basis of the weight and movement characteristics of the focus lens 3 and the amount of power that can be consumed, and is stored in advance in a memory (not shown) as data.

  In step S <b> 709, the system controller 13 determines whether or not the focus lens 3 is moved in the direction of the acceleration, that is, in the optical axis direction (Z-axis direction) by driving the focus motor 9. If the focus lens 3 has been moved in the direction of acceleration, the process proceeds to step S710, and if not, the process proceeds to step S711.

  In step S710, the system controller 13 stops driving the focus motor 9 (movement of the focus lens 3).

  In step S711, the system controller 13 applies a holding excitation voltage corresponding to the acceleration obtained in step S706 to the focus motor 9 in order to hold the position of the focus lens 3. That is, the holding excitation voltage is variably controlled as shown in FIG. Then, the process proceeds to step S719.

  In step S712, the system controller 13 determines whether the magnitude of the acceleration equal to or greater than the predetermined value B acquired in step S706 is smaller than the predetermined value C (second predetermined value) set larger than the predetermined value B. Determine whether. If it is smaller than the predetermined value C, the process proceeds to step S717. If it is equal to or larger than the predetermined value C (or larger than the predetermined value C), the process proceeds to step S714. The predetermined value C here is determined on the basis of the weight and movement characteristics of the focus lens 3, the amount of power that can be consumed, and the like, and is stored in advance in a memory (not shown) as data.

  In step S714, the system controller 13 considers that there is a high possibility that the focus motor 9 has stepped out due to acceleration equal to or greater than the predetermined value C, and accurate position control of the focus lens 3 cannot be performed, and performs processing for prohibiting shooting. Do. In other words, a process for prohibiting the use of the camera is performed. The photographing prohibition process is the same as the process described in the third embodiment.

  Next, in step S715, the system controller 13 acquires the current acceleration (acceleration in the Z-axis direction) from the acceleration sensor 15 again.

  In step S716, the system controller 13 determines whether the magnitude of the acceleration acquired in step S715 is smaller than a predetermined value C. If it is smaller than the predetermined value C, the process proceeds to step S717. If it is equal to or larger than the predetermined value C (or larger than the predetermined value C), the process returns to step S715, and the acceleration acquisition is repeated. The predetermined value C in this step may be a value smaller than the predetermined value C in step S712.

  In step S <b> 717, the system controller 13 drives the focus motor 9 via the focus control unit 11 and performs a reset process for the focus lens 3. That is, when the magnitude of the acceleration acquired in step S715 is equal to or greater than the predetermined value C, the focus lens 3 is reset after the acceleration is smaller than the predetermined value C. When this reset process is completed, the system controller 13 cancels the photographing prohibition in step S718. Thereafter, the process returns to step S704.

  Similarly to the third embodiment, even when the focus motor 9 steps out due to the acceleration generated by the impact applied to the camera and accurate position control of the focus lens 3 cannot be performed, the reset lens can accurately correct the focus lens 3. Position control can be resumed. Further, until the reset process is completed, the focus lens 3 that cannot perform accurate position control causes a defocusing to prevent photographing, thereby preventing the generation of a defocused photographed image. it can.

  In step S719, the system controller 13 determines whether or not a shooting start operation has been performed on the operation unit 14, and if a shooting start operation has been performed, the process proceeds to step S720. If the shooting start operation has not been performed, the process returns to step S704.

  In step S720, the system controller 13 performs shooting processing. In this photographing process, automatic exposure (AE) control and AF control are performed, and a photographed image is generated from an imaging signal obtained by photoelectrically converting a subject image by the image sensor 4.

  As described above, according to the present embodiment, even when the camera is subjected to shock or vibration, the focus motor 9 is stepped out and the unexpected position of the focus lens 3 is suppressed while suppressing an increase in power consumption. Can be prevented from being displaced. In addition, the position of the normal focus lens 3 can be controlled.

  Each embodiment described above is only a representative example, and various modifications and changes can be made to each embodiment in carrying out the present invention.

  It is possible to provide an optical device such as a camera that prevents the displacement of the optical element due to the stepping motor out of step even when subjected to an impact or vibration.

3 Focus lens 9 Focus motor 11 Focus control unit 13 System controller 15 Acceleration sensor

Claims (11)

An optical instrument having a movable optical element,
A stepping motor for moving the optical element;
Control means for controlling the driving of the stepping motor;
Acceleration detecting means for detecting acceleration acting on the optical device in a movable direction of the optical element;
The control means applies to the stepping motor to hold the position of the optical element in accordance with the acceleration detected by the acceleration detection means in a state where the stepping motor does not move the optical element. An optical device characterized by controlling an excitation voltage.   The control means sets the excitation voltage to a fixed value when the acceleration is smaller than a predetermined value, and sets the excitation voltage according to the acceleration in a voltage range higher than the fixed value when the acceleration is larger than the predetermined value. The optical apparatus according to claim 1, wherein the optical apparatus is changed. An optical instrument having a movable optical element,
A stepping motor for moving the optical element;
Control means for controlling the driving of the stepping motor;
Acceleration detecting means for detecting acceleration acting on the optical device in a movable direction of the optical element;
When the acceleration is detected by the acceleration detecting means in a state where the stepping motor does not move the optical element, the control means moves the optical element so as to move the optical element in the direction of the acceleration. An optical device that is driven.   4. The optical apparatus according to claim 3, wherein the control unit drives the stepping motor such that a moving speed of the optical element by the stepping motor increases as the acceleration increases. 5. An optical instrument having a movable optical element,
A stepping motor for moving the optical element;
Control means for controlling the driving of the stepping motor;
Acceleration detecting means for detecting acceleration acting on the optical device in a movable direction of the optical element;
The control means drives the stepping motor to move the optical element to a reference position for detecting the position of the optical element in response to the acceleration being detected by the acceleration detecting means. Optical equipment.   The optical device performs a process of prohibiting use of the optical device until the optical element is moved to the reference position by driving the stepping motor in response to detection of the acceleration by the acceleration detection unit. The optical apparatus according to claim 5. An optical instrument having a movable optical element,
A stepping motor for moving the optical element;
Control means for controlling the driving of the stepping motor;
Acceleration detecting means for detecting acceleration acting on the optical device in a movable direction of the optical element;
The control means includes
When the acceleration detected by the acceleration detecting means is smaller than a first predetermined value in a state where the stepping motor does not move the optical element, the position of the optical element is held according to the acceleration. In order to control the excitation voltage applied to the stepping motor for
When the stepping motor does not move the optical element, if the acceleration is larger than the first predetermined value and smaller than the second predetermined value, the optical element is moved in the acting direction of the acceleration. Drive the stepping motor as
When the acceleration is larger than the second predetermined value, the stepping motor is driven so as to move the optical element to a reference position for detecting the position of the optical element. A method for controlling an optical apparatus having a movable optical element and a stepping motor for moving the optical element,
Detecting an acceleration acting on the optical device in a movable direction of the optical element;
Controlling the excitation voltage applied to the stepping motor to maintain the position of the optical element in accordance with the detected acceleration in a state where the stepping motor is not moving the optical element. A method for controlling an optical instrument. A method for controlling an optical apparatus having a movable optical element and a stepping motor for moving the optical element,
Detecting an acceleration acting on the optical device in a movable direction of the optical element;
And driving the stepping motor to move the optical element in the direction of the acceleration when the acceleration is detected in a state where the optical element is not moved by the stepping motor. To control optical equipment. A method for controlling an optical apparatus having a movable optical element and a stepping motor for moving the optical element,
Detecting an acceleration acting on the optical device in a movable direction of the optical element;
And a step of driving the stepping motor to move the optical element to a reference position for detecting the position of the optical element in response to detection of the acceleration. Method. A method for controlling an optical apparatus having a movable optical element and a stepping motor for moving the optical element,
Detecting an acceleration acting on the optical device in a movable direction of the optical element;
When the acceleration detected by the acceleration detecting means is smaller than a first predetermined value in a state where the stepping motor does not move the optical element, the position of the optical element is held according to the acceleration. For controlling the excitation voltage applied to the stepping motor for
When the stepping motor does not move the optical element, if the acceleration is larger than the first predetermined value and smaller than the second predetermined value, the optical element is moved in the acting direction of the acceleration. Driving the stepping motor as follows:
And driving the stepping motor to move the optical element to a reference position for detecting the position of the optical element when the acceleration is greater than the second predetermined value. Device control method.