JP2014089471A - Optical device and method for controlling the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical device capable of preventing deterioration of image quality by suppressing camera shake in both of moving image shooting and still image shooting.SOLUTION: The optical device includes: a correction lens for correcting blur of an image formed by an imaging optical system; a shake detection part 201 for detecting the shake of the device; a position detection part 207 for detecting the position of the correction lens; a calculation part 204 for calculating a drive target position of the correction lens on the basis of the amount of the shake which is the output of the shake detection part 201 and the position of the correction lens; a driving part 206 for driving the correction lens to the drive target position; and a control part 104 for causing the position resolution of the correction lens in shooting a still image to be higher than that in shooting a moving image. The control part 104 also performs a control such that when shooting a moving image, the position resolution of the correction lens in the case where the output of the shake detection part 201 is a predetermined value or less becomes higher than that in the case where the output from the shake detection part 201 is greater than the predetermined value.

Description

  The present invention relates to an optical instrument and a control method thereof, and more particularly to an optical instrument having a camera shake correction function and a control method thereof.

  There is known an optical apparatus including a shake correction device that detects a shake of an optical apparatus such as a digital camera and drives a movable imaging lens so as to correct image blur caused by the shake. In recent years, there has also been known a technique for expanding the image stabilization range on the wide end side during moving image recording and enhancing the effect of image stabilization compared to the conventional method for large camera shake caused by shooting while walking (hereinafter referred to as large image stabilization). ).

  Further, for example, an optical apparatus that performs correction control for large camera shake is disclosed in Patent Document 1.

JP 2006-47742 A

  However, in the related art disclosed in Patent Document 1 described above, when the movable range is expanded in accordance with the posture information for holding the optical device, the drive resolution of the shift lens is lowered. In an imaging apparatus capable of shooting both a moving image and a still image, the effect is noticeable as deterioration of the camera shake correction effect at the time of still image shooting that requires higher resolution. In addition, due to the characteristics of the optical lens, there is a concern that the image quality may be degraded such as resolution degradation in the still image when the movable range of the shift lens is widened.

  The present invention has been made in view of the above-described problems, and an object thereof is to achieve both the effect of suppressing camera shake and the prevention of deterioration of image quality in both moving images and still image shooting.

  An optical apparatus according to the present invention includes a correction lens that corrects blurring of an image formed by the photographing optical system by moving in a first direction different from the optical axis, a shake detection unit that detects shake of the apparatus, Position detection means for detecting the position of the correction lens in the first direction; and conversion means for converting a voltage signal output from the position detection means and indicating position information of the correction lens in the first direction into a digital signal. Calculating means for calculating a drive target position of the correction lens based on a shake amount as an output of the shake detection means and a position of the correction lens; drive means for driving the correction lens to the drive target position; Control means for making the position resolution in the first direction of the correction lens at the time of still image shooting higher than the position resolution of the correction lens in the first direction at the time of moving image shooting, and the control means, Video The positional resolution in the first direction of the correction lens when the shake amount as the output of the shake detection means is less than or equal to a predetermined value, and when the shake amount as the output of the shake detection means is greater than a predetermined value. The correction lens is controlled to be higher than the position resolution in the first direction.

  According to the present invention, it is possible to achieve both the effect of suppressing camera shake and the prevention of deterioration of image quality in both moving image and still image shooting.

1 is a block diagram of an imaging apparatus according to an embodiment of the present invention. The block diagram of the vibration proof control part which concerns on one Embodiment of this invention. The schematic diagram of the hole adjustment which concerns on one Embodiment of this invention. FIG. 5 is a detailed explanatory diagram of AD resolution according to an embodiment of the present invention. The AD resolution switching figure of still picture mode and animation mode concerning one embodiment of the present invention. 6 is a flowchart of AD resolution switching according to an embodiment of the present invention.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of an optical apparatus according to an embodiment of the present invention. This optical device is a digital camera mainly for taking still images and moving images.

  In FIG. 1, reference numeral 101 denotes a zoom unit, which includes a zoom lens that performs zooming. Reference numeral 102 denotes a zoom drive control unit that controls the drive of the zoom unit 101. Reference numeral 103 denotes a correction lens (shift lens, correction member) whose position can be changed in a direction perpendicular to the optical axis. Reference numeral 104 denotes an image stabilization control unit that controls the driving of the correction lens 103.

  Reference numeral 105 denotes an aperture / shutter unit. Reference numeral 106 denotes an aperture / shutter drive control unit, which controls the drive of the aperture / shutter unit 105. A focus unit 107 includes a lens that performs focus adjustment. A focus drive control unit 108 controls the drive of the focus unit 107. The zoom unit 101, the correction lens 103, the aperture / shutter unit 105, and the focus unit 107 are disposed in a photographing lens that forms a subject image.

  Reference numeral 109 denotes an imaging unit that converts an optical image that has passed through each lens group into an electrical signal. Reference numeral 110 denotes an imaging signal processing unit that converts an electrical signal output from the imaging unit 109 into a video signal. A video signal processing unit 111 processes the video signal output from the imaging signal processing unit 110 according to the application. Reference numeral 112 denotes a display unit, which displays an image as necessary based on a signal output from the video signal processing unit 111. Reference numeral 113 denotes a power supply unit that supplies power to the entire system according to the application. An external input / output terminal unit 114 inputs / outputs communication signals and video signals to / from the outside. Reference numeral 115 denotes an operation unit for operating the system. Reference numeral 116 denotes a storage unit that stores various data such as video information. Reference numeral 117 denotes an attitude information control unit that determines the attitude of the imaging apparatus and provides attitude information. A camera system control unit 118 controls the entire system.

  Next, a schematic operation of the digital camera having the above configuration will be described.

  The operation unit 115 includes an anti-shake switch (switching means) that enables the user to select a shake correction (anti-shake) mode. When the shake correction mode is selected by the image stabilization switch, the camera system control unit 118 instructs the image stabilization control unit 104 to perform the image stabilization operation, and the image stabilization control unit 104 that receives the instruction instructs the image stabilization off. Anti-vibration operation is performed. In addition, the operation unit 115 includes a shooting mode selection switch that allows one of a still image shooting mode and a moving image shooting mode to be selected, and changes the operating condition of each actuator in each shooting mode. Can do.

  The operation unit 115 includes a shutter release button configured such that the first switch (SW1) and the second switch (SW2) are sequentially turned on according to the amount of pressing. The switch SW1 is turned on when the shutter release button is depressed approximately half, and the switch SW2 is turned on when the shutter release button is depressed to the end. When the switch SW1 is turned on, the focus drive control unit 108 drives the focus unit 107 to perform focus adjustment, and the aperture / shutter drive control unit 106 drives the aperture / shutter unit 105 to set an appropriate exposure amount. To do. When the switch SW2 is turned on, image data obtained from the light image exposed to the imaging unit 109 is stored in the storage unit 116.

  The operation unit 115 includes a moving image recording switch. Movie recording starts after the switch is pressed, and recording is ended when the switch is pressed again during recording. The operation unit 115 also includes a playback mode selection switch that can select a playback mode, and stops the image stabilization operation in the playback mode.

  Further, the operation unit 115 includes a zooming switch for instructing zoom zooming. When an instruction for zooming magnification is given by the zooming switch, the zoom drive control unit 102 that has received the instruction via the camera system control unit 118 drives the zoom unit 101 to move the zoom unit 101 to the instructed zoom position. Let At the same time, based on the image information sent from the imaging unit 109 and processed by each signal processing unit (110, 111), the focus drive control unit 108 drives the focus unit 107 to perform focus adjustment.

  FIG. 2 is a block diagram illustrating in more detail between the image stabilization control unit 104 and the camera system control unit 118. The configuration of FIG. 2 described below is a shake correction system for performing image blur correction control.

  Since the configuration is the same in the Pitch direction and the Yaw direction, only one axis will be described. Reference numeral 201 denotes an angular velocity detection unit (hereinafter referred to as a gyro), which detects angular velocity data and outputs it as a voltage. Reference numeral 202 denotes an angular velocity AD conversion unit that converts data output from the gyro 201 into digital data.

  Reference numeral 203 denotes a gyro gain unit, which is an output adjustment unit for aligning output variations of the gyro. A cancellation amount calculation unit 204 integrates angular velocity data and converts it into angle data. The direction opposite to the camera shake angle data is used as camera shake cancellation data, and the characteristics are changed in accordance with the driving range of the correction lens 103. Is calculated. At this time, the drive target value (command value) is obtained by adding the shake cancel amount to the command value center value 212. Here, the range of the command value is equivalent to the shift lens AD value. The data output by the cancellation amount calculation unit (target position calculation unit) is notified to the shift lens position control unit 205.

  A shift lens position detection unit 207 detects position information in a direction perpendicular to the optical axis of the shift lens and outputs it as a voltage. Although a Hall element is used here, other detection means may be used. A shift lens position AD conversion unit 208 converts data output from the shift lens position detection unit 207 into digital data.

  The shift lens position control unit 205 calculates a difference between the shake cancellation amount and the position data detected by the shift lens position AD conversion unit 208, and performs feedback control so that the deviation approaches zero. Finally, a signal for driving the correction lens 103 is notified to the shift lens driving driver unit 206. When notified of the drive signal, the shift lens drive driver unit 206 drives the correction lens 103 correspondingly.

  Reference numeral 209 denotes a hole offset portion. By applying a voltage to the amplification element of the Hall element output, a voltage offset is given to the amplified Hall output, and the shift lens position can be adjusted.

  Reference numeral 210 denotes a hall gain unit. The output of the Hall element is controlled by applying a predetermined voltage to the input part of the Hall element. Reference numeral 211 denotes an attitude detection unit. In this embodiment, the attitude of the optical device is determined from information from the shift lens position control unit 205. Note that the posture detection unit 211 may determine the posture of the device using a sensor such as an acceleration sensor or a posture sensor.

  Here, the details of the Hall offset adjustment using the Hall offset unit 209 and the Hall gain adjustment (shift lens position AD resolution setting) using the Hall gain unit 210 will be described. Hereinafter, the hall offset adjustment and the hall gain adjustment are collectively referred to as hall adjustment.

  The method of calculating the mechanical center of the shift lens movement using the hole offset unit 209 notifies the hole offset unit 209 of a movement command for driving the shift lens to the limit in the horizontal and vertical directions on the mechanical drive range surface, and shifts. Drive the lens. The middle point of each limit point of the driving range at this time is the mechanical center (the centering of the mechanism by the hole offset unit 209 is called hole offset adjustment). The center position of the shift lens obtained as a result is called the mechanical center, and becomes the driving center position during image stabilization. (See FIG. 3 (a)).

  A method of setting the shift lens position AD resolution (shift lens position detection accuracy) using the hall gain unit 210 will be described with reference to FIG. First, the shift lens position control unit 205 is notified of a movement command for driving the shift lens in the horizontal and vertical directions on the mechanical drive range surface by a predetermined amount (for example, 50 LSB), and the shift lens is driven. The value of the Hall gain unit 210 is set so that the amount of change in the angle of view at this time is 0.1 degree. The value obtained as a result is called a hall gain value, and this adjustment is called hall gain adjustment. In this Hall gain adjustment, the shift lens position AD resolution is determined by how many LSBs are driven with respect to the angle of view movement of 0.1 degrees. In this embodiment, this shift lens position AD resolution is used as control accuracy (detection accuracy). Here, the hole adjustment is performed at the tele end position.

  FIG. 4 shows an example of the shift lens AD resolution. The AD range of the shift lens is 0 to 600, and the center position is 300. When considering the still image mode as a reference as shown in FIG. 4A, it is assumed that the shift lens driving amount is set to 200 LSB when the 0.4 degree angle of view at the tele end is changed by the hall gain adjustment. . Here, since the higher resolution of the shift lens AD is advantageous for camera shake correction during still image shooting, the resolution at the telephoto end is set to be as high as possible.

  Here, the AD resolution at the wide end is determined by the difference of the shift lens movement amount per predetermined angle of view change between the tele end and the wide end (hereinafter, this movement amount is referred to as shift lens sensitivity). This shift lens sensitivity varies depending on the lens structure and type.

  For example, in the case of a certain low magnification lens, when the shift lens sensitivity ratio between the tele end and the wide end is 2: 1, when the shift lens AD resolution with an angle of view variation of 0.4 degree at the tele end is 200 LSB, 100LSB at the wide end. At this time, the movable range of the shift lens is ± 1.2 degrees at the wide end due to the limitation of the AD range. With this setting, when shake prevention is performed in the moving image mode, the AD range is insufficient, and it is not possible to cope with large shakes such as walking shots.

  Therefore, as shown in FIG. 4B, when the AD resolution is set so that the movable range is as wide as 4.8 degrees at the wide end in order to cope with the large shake prevention in the moving image mode (0.4 degrees). This time, the AD resolution at the tele end is lowered (50 LSB per 0.4 degree). If the setting is switched to the still image mode and still image shooting is performed, the camera shake correction effect is reduced.

  Here, the image stabilization when the shift lens AD resolution is lowered during the moving image mode is not noticeable when the moving image is recorded, but the deterioration of the image stabilization effect is less noticeable than when the still image is displayed. In reality, almost no deterioration is known. The reason is that a still image has a higher image quality required than a moving image, so that the number of recorded pixels is larger when recording a still image than when recording a moving image. In terms of image quality, the resolution of moving images is not as significant as that of still images.

  If the shift lens AD resolution is adjusted for still image shooting in this way, the movable range of the shift lens at the time of moving image recording cannot be secured, and if it is adjusted to the driving range required by the shake correction function at the time of moving image shooting, There arises a problem that the camera shake correction effect is lowered.

  Therefore, in this embodiment, as shown in FIG. 5, means (switching means) for switching the shift lens AD resolution when switching between the still image mode and the moving image mode is provided. Change the hall gain value (analog gain) as a switching method. Note that a first mode in which shake correction is performed using the shift lens AD resolution in the moving image shooting mode is a first mode in which shake correction is performed using the shift lens AD resolution in the still image shooting mode. The shift lens AD resolution in the second mode is set to be higher than the shift lens AD resolution in the first mode.

  Here, the AD resolution switching by the hall adjustment value is performed at the start of moving image recording and at the end of moving image recording, and may be set to the AD resolution for moving image shooting only during moving image recording. For digital cameras that do not switch between still image mode and movie mode, AD resolution for still image shooting is used during normal standby, and control resolution is switched at the start of movie recording and at the end of movie recording. It may be set to the AD resolution for use.

  Here, the reason for switching not only the Hall gain adjustment value but also the Hall offset adjustment value when switching the AD resolution will be described. The change in the Hall output voltage value when the Hall offset adjustment value is changed by 1 LSB is a constant value in terms of the circuit configuration. When the shift lens AD width per 0.4 degrees is set by the hall gain adjustment, the hall output voltage width per field angle of 0.4 degrees is also determined. Here, for example, when the AD width per 0.4 degrees is set to 200 LSB and 50 LSB, the voltage width is also four times different, and therefore the correction angle of view per hole offset value 1 LSB is also four times different. become. Therefore, when the Hall gain value is changed, the Hall offset value corresponding to the Hall gain value also differs. As a result, changing the AD resolution requires changing both the Hall gain adjustment value and the Hall offset adjustment value.

  Here, at the time of moving image shooting, it is not always the case that the AD resolution should be switched to moving image shooting. For example, in the anti-vibration off mode, the shift lens is fixed at the center position, so there is no need to widen the movable range and there is no need to change the AD resolution. Similarly, it is not necessary to widen the shift lens driving range even when the image stabilization is on and when the amount of shaking is small, such as when the camera is fixed on a tripod. In such a case, it is not necessary to lower the AD resolution to lower the controllability of the shift lens, and it is preferable not to switch the AD resolution unless it is necessary, because there is a discontinuity in the shift lens control due to switching. . In view of these circumstances, FIG. 6 shows an AD resolution switching flowchart when recording a moving image.

  In FIG. 6, the AD resolution for still image shooting is set at the normal standby time when still images and moving images are not recorded, and the AD resolution is switched at the start of moving image recording and at the end of moving image recording. Assume that the AD resolution is set.

  First, at the start of moving image recording, it is determined in S101 whether the image stabilization mode is off. If it is off, it is determined that there is no need to widen the vibration-proof drive range because the shift lens remains fixed at the center during video recording (switching determination), and the AD resolution holds the AD resolution for still image shooting. The moving image recording is performed until the moving image recording ends (S109).

  Next, if the image stabilization mode is on, it is determined whether the camera shake amount at that time is equal to or less than a predetermined value (S102). Here, as a threshold value of the shaking amount, a method of obtaining the shaking amount by detecting the magnitude, amplitude, and frequency of the shaking waveform is conceivable. For example, the magnitude of the hand shake waveform as the threshold value of the shake amount may be about the amount of hand shake (for example, 0.3 degrees) that occurs when the camera is held in a normal still image shooting, or the still image shooting AD resolution is It is good also as the amount of shaking which can be shake-proof in a state. Furthermore, by using a threshold value for entering the tripod processing, it may be possible to use a determination as to whether the amplitude and frequency of the hand movement waveform are equal to or less than the respective threshold values, and various settings can be made according to the application. In addition to using the shake amount as a determination criterion, a drive command value (drive target value of the correction lens 103) or a shift lens AD value (position of the correction lens 103) may be used.

  If the amount of shaking is larger than the predetermined value, the process proceeds to S107 and is switched to the moving picture shooting AD resolution. After switching, the moving image recording is performed until the moving image recording ends (S109).

  If the amount of shaking is equal to or smaller than the predetermined value in S102, the process proceeds to S103, and moving image shooting is started with the still image shooting AD resolution. If the moving image recording ends in S104 after the moving image recording starts, the moving image recording ends with the still image shooting AD resolution. In this case, the AD resolution is not switched at the start / end of moving image recording.

  If it is determined in S104 that the recording is not completed but the recording is continued, it is determined again in S105 whether or not the shaking amount is equal to or less than a predetermined value. Here, whether or not the shaking amount is equal to or less than a predetermined value may be determined periodically (for example, at a cycle of 1 ms), or may be determined while constantly observing. If the amount of shaking is less than the predetermined value, continue to observe the amount of shaking until the end of the video recording, and if the amount of shaking is less than the predetermined value until the end of the movie, the still image shooting AD resolution will remain. In this case as well, AD resolution switching is not performed during moving image recording. If the amount of shaking becomes larger than a predetermined value during moving image recording in S105, the process proceeds to S106 and the AD resolution for moving image shooting is set.

  Thereafter, the moving image recording is performed until the moving image recording ends (S109).

  With the above processing, when it is not necessary to switch the AD resolution at the time of moving image recording and during moving image recording, the moving image is recorded with the still image shooting AD resolution, so that the shift lens control at the time of unnecessary AD resolution switching is performed. There is no discontinuity. And it becomes possible to perform optimal vibration-proof control.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary. For example, a mechanism for driving the image sensor instead of the shift lens may be used. In the present invention, a digital camera is taken as an example of an optical device. However, the present invention may be an electronic device such as a digital video camera, a digital single lens reflex interchangeable lens, a mobile phone equipped with a shake correction mechanism, or a game. .

Claims (2)

A correction lens that corrects blurring of an image formed by the imaging optical system by moving in a first direction different from the optical axis;
Shake detection means for detecting the shake of the device;
Position detecting means for detecting the position of the correction lens in the first direction;
Conversion means for converting a voltage signal indicating position information in the first direction of the correction lens output from the position detection means into a digital signal;
Calculation means for calculating a drive target position of the correction lens based on a shake amount which is an output of the shake detection means and a position of the correction lens;
Drive means for driving the correction lens to the drive target position;
Control means for making the position resolution in the first direction of the correction lens at the time of still image shooting higher than the position resolution of the correction lens in the first direction at the time of moving image shooting;
The control means determines the positional resolution in the first direction of the correction lens when the shake amount, which is the output of the shake detection means, is equal to or less than a predetermined value during moving image shooting, and the shake amount, which is the output of the shake detection means. The optical apparatus is controlled so as to be higher than the position resolution in the first direction of the correction lens when is larger than a predetermined value. A method for controlling an optical instrument,
A shake detection step of detecting shake of the optical instrument;
A position detection step of detecting the position of the correction lens in the first direction for correcting the blur of the image formed by the photographing optical system by moving in a first direction different from the optical axis;
A conversion step of converting a voltage signal indicating position information in the first direction of the correction lens output in the position detection step into a digital signal;
A calculation step of calculating a drive target position of the correction lens based on the shake amount output in the shake detection step and the position of the correction lens;
A driving step of driving the correction lens to the driving target position;
A control step of making the position resolution in the first direction of the correction lens at the time of still image shooting higher than the position resolution of the correction lens in the first direction at the time of moving image shooting;
In the control step, the position resolution in the first direction of the correction lens when the shake amount, which is the output of the shake detection step, is equal to or less than a predetermined value during moving image shooting, is the shake amount, which is the output of the shake detection step. A control method for an optical apparatus, wherein control is performed so that the correction lens is higher than the position resolution in the first direction when the correction lens is larger than a predetermined value.

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