JP2012123065A - Optical device and control method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To compatibly achieve a suppression effect of camera shake and prevention of deterioration of image quality in both of photographing of a moving image and a still image.SOLUTION: An optical device includes: a correction part arranged in a photographic lens to correct blurring of an image formed by the photographic lens by moving in a direction perpendicular to an optical axis of the photographic lens; a shake detection part 201 for detecting shake of the optical device; a position detection part 207 for detecting the position of the correction part in a direction perpendicular to the optical axis; a drive control part 205 for calculating a drive target value of the correction part based on an output of the shake detection part and the positional information on the correction part; and a switching part for switching detection accuracy of the position detection means so that resolution in a state in which a still image is photographed is larger than that in a state in which a moving image is photographed when photographing a moving image and when photographing a still image by using the optical device. When the switching part switches the detection accuracy of the position detection part, the switching part aligns a drive center position of the correction part when photographing a moving image with a drive center position of the correction part when photographing a still image.

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.

  2. Description of the Related Art There is known an optical apparatus provided with a shake correction device that detects a shake of an optical apparatus such as a digital camera or an imaging apparatus and drives a movable imaging lens so as to correct an 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 image pickup apparatus that performs correction control for large camera shake is disclosed in Patent Document 1.

JP 2006-47742 A

  However, in the conventional technique disclosed in Patent Document 1 described above, when the movable range is expanded in accordance with the posture information for holding the imaging device, the driving resolution of the shift lens is lowered. In an imaging apparatus capable of shooting both moving images and still images, the effect is noticeable as deterioration of the camera shake correction effect during 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 is an optical apparatus that is disposed on a photographic lens and corrects blurring of an image formed by the photographic lens by moving in a direction perpendicular to the optical axis of the photographic lens. Means, a shake detection means for detecting shake of the optical apparatus, a position detection means for detecting a position of the correction means in a direction perpendicular to the optical axis, an output of the shake detection means, and detection by the position detection means A drive control unit that calculates a drive target value of the correction unit based on the position information of the correction unit, and a case where a moving image is shot using the optical device and a case where a still image is shot. Switching means for switching the detection accuracy of the position detection means so that the resolution is higher in the state of taking the still image than in the state of taking a picture, and the switching means includes the position detection When switching the detection accuracy of the stage, and wherein the match the driving center position of the correction means in the case of shooting a still image driving center position of the correction means when recording movies.

  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. The block diagram of the shift lens position control part 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. The AD resolution switching flowchart which concerns on one Embodiment of this invention. The flowchart of the hall | hole adjustment which concerns on one Embodiment of this 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 will be described as 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) 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 optical device 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 image stabilization switch that enables selection of a shake correction (image stabilization) 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.

  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 the angular velocity data and converts it into angle data, sets the reverse direction of the camera shake angle data as camera shake cancel data, changes the characteristics according to the driving range of the correction lens unit 103, and cancels the shake. The amount 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 unit 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 optical device using a sensor such as an acceleration sensor or a posture detection 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. 3A).

  The shift lens position AD resolution setting method using the hall gain unit 210 (see FIG. 3B) is a movement command for driving the shift lens in a horizontal and vertical direction on the mechanical drive range surface (for example, 50 LSB). Is sent to the shift lens position control unit 205 to drive the shift lens. 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 is a block diagram of the shift lens position control unit 205 in one embodiment. In FIG. 4, 301 is an integral compensator (Ki), 302 is a proportional compensator (Kp), and 303 is a differential compensator (Kd). Reference numeral 304 denotes an integral compensation value reading unit. A gain adjustment unit 305 amplifies a value with respect to the output.

  In the shift lens position control unit 205, an integral compensation value Evi that is an output value of the integral compensator (Ki) 301 is input to the integral compensation value reading unit 304. In this embodiment, the integral compensation value Evi is used for posture determination. Used.

  Here, assuming that the difference between the target position and the current position in the PID control is the deviation amount e, the feedback amount PIDout to be output is expressed as in Expression (1). Here, the integral compensation value Evi is Ki∫edt.

PIDout = Kp × e + Kd × de / dt + Ki∫edt (1)
In FIG. 4, the target position is a value calculated by the cancellation amount calculation unit 204, and the current position is a value of the shift lens position AD conversion unit 208. After the PID control calculation, the gain adjustment unit 305 notifies the shift lens drive DA conversion unit 206 of a product obtained by multiplying a predetermined amount of gain (usually 1).

  FIG. 5 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. 5A, 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. 5B, in order to cope with the large shake prevention in the moving image mode, when the AD resolution is set so that the movable range is wide as 4.8 degrees at the wide end (0.4 degrees). This time, the AD resolution at the telephoto end is reduced (50 LSB per 0.4 degree), and if the setting is switched to the still image mode and still image shooting is performed, the camera shake correction effect is remarkably reduced.

  Here, the image stabilization is reduced when the shift lens AD resolution is reduced in the moving image mode. However, when moving images are recorded, the deterioration of the image stabilization effect is not as conspicuous as that of the still image. In reality, almost no deterioration is known. The reason for this is that since still images require higher image quality than moving images, the number of recorded pixels is larger when recording still images than when recording moving images. 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 wide driving range required for moving images, the camera shake correction effect at the time of still image shooting is reduced. The problem of doing so will arise.

  Therefore, in the present embodiment, as shown in FIG. 6, 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. This state is shown in the flowchart of FIG.

  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, the AD resolution for still image shooting is set during normal standby, and the AD 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.

  Next, Hall adjustment for switching the AD resolution will be described. In order to switch the shift lens AD resolution when switching between the still image mode and the moving image mode, it is necessary to perform hall gain and hole offset adjustment suitable for each mode in the two modes of the still image mode and the moving image mode at the tele end. . FIG. 8 shows a flowchart of adjustment. Here, as an example, the AD width per 0.4 degrees is set to 200 LSB in the still image mode and 50 LSB in the moving image mode.

First, in S201, the hall gain adjustment of FIG. 3B is performed for still image shooting. Here, as an example, when the shift lens is driven by 200 LSB, the angle of view is adjusted to change by 0.4 degrees. Next, in S202, the hole offset adjustment shown in FIG. After completing the hole adjustment for still image shooting, the hall adjustment for moving image shooting is performed. (S203)
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 corresponding Hall offset value is also different. As a result, changing the AD resolution requires changing both the Hall gain adjustment value and the Hall offset adjustment value.

  In step S203, a hall gain adjustment for moving image shooting is performed. Here, the angle of view is adjusted to change by 0.4 degrees when the shift lens is driven by 50 LSB. In the hall gain adjustment for moving image shooting, the AD gain ratio for changing the angle of view of 0.4 degrees may be used as the hall gain adjustment value. The calculation formula in that case is shown in Formula (2).

Hall gain adjustment value for moving image shooting = Hall gain adjustment value for still image shooting × Movie AD width / Still image AD width (2)
In step S204, a hall offset adjustment for moving image shooting is performed. In the hall offset adjustment for moving image shooting, the mechanical center is not obtained again using the mechanical drive limit point as shown in FIG. 3A, but the moving image shooting is performed at the drive center position of the still image shooting hole offset adjustment obtained in S201. Make adjustments so that the drive center position matches. However, as described above, the correction field angle amount per hole offset value 1LSB is four times larger at the time of moving image shooting, so there are cases where the drive center position cannot be adjusted only by the hole offset.

  Here, if the drive center position is different between still image shooting and moving image shooting, a change in the angle of view occurs when the AD resolution is switched, resulting in deviation from the angle of view intended by the user.

  In such a case, the drive center alignment is performed using the command center value 212 of the shift lens control together with the hole offset. Compared with the hole offset, the shift lens control has a sufficiently finer change in the angle of view per LSB, so that the drive center position can be adjusted with higher accuracy. As described above, when the command center value is used together with the hall offset for the alignment of the drive center, both the hall adjustment value and the command center value are switched when the AD resolution is switched.

  In this flowchart, the hole adjustment for moving image shooting (S203) is performed after the hole adjustment for still image shooting (S202), but the hole adjustment for moving image shooting may be performed first.

  Next, switching of AD resolution will be described with reference to the flowchart of FIG.

  First, when the power of the digital camera is turned on in S101, the process proceeds to S102. If it is determined in S102 that the shooting mode switch has been switched, the process proceeds to S103. In S103, it is determined whether the still image mode or the moving image mode. If it is the still image mode, the process proceeds to S104. In S104, a still image hole adjustment value) is set. Thus, the shift lens AD resolution is set for the still image mode.

  Next, the process proceeds to S105. In S105, a still image command value is set. In the still image mode, the command value is expressed by the following equation (3).

Still image command value = shake cancel amount + still image command center value (3)
In step S106, various image stabilization parameters for a still image are set. Here, the various image stabilization parameters indicate parameters for controlling the appearance of an image during a panning operation, a gain value (gain adjustment unit 305) for shift lens control, an image stabilization movable range, and the like.

  Next, in S110, it is determined whether or not the power switch is ON. If the power switch is ON, the process returns to S102 to continue to monitor the image stabilization operation and the mode changeover switch. If there is no change in the mode change switch in S102, the process proceeds to S110 and the same operation is performed.

  If it is determined in S103 that the moving image mode is selected, the flow advances to S107 to set a moving image hall adjustment value. Then, the process proceeds to S108, and the moving image command value conversion and setting are performed according to the following equation (3).

Movie command value = (Still image command value-Still image command center value) x (Movie AD width / Still image AD width)
+ Movie command center value (3)
Next, the process proceeds to S109 to set a vibration isolation parameter for the moving image. The setting items are the same as those for the still image in S106.

  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 (6)

An optical instrument,
A correction unit that is disposed on the photographic lens and corrects blurring of an image formed by the photographic lens by moving in a direction perpendicular to the optical axis of the photographic lens;
Shake detection means for detecting shake of the optical instrument;
Position detecting means for detecting a position of the correcting means in a direction perpendicular to the optical axis;
Drive control means for calculating a drive target value of the correction means based on the output of the shake detection means and the position information of the correction means detected by the position detection means;
When the moving image is shot using the optical device and when the still image is shot, the position detection unit detects the resolution so that the still image shooting state is larger than the moving image shooting state. Switching means for switching the accuracy,
The switching means, when switching the detection accuracy of the position detection means, matches the drive center position of the correction means when shooting a moving image to the drive center position of the correction means when shooting a still image. Optical equipment.   The optical apparatus according to claim 1, wherein the switching unit switches an analog gain of the position detection unit.   3. The optical apparatus according to claim 1, wherein the switching unit switches the detection accuracy of the position detection unit when switching between a mode for capturing the moving image and a mode for capturing the still image. 4.   3. The switching unit according to claim 1, wherein the switching unit performs switching of detection accuracy of the position detection unit at the time of switching between the start of shooting of the moving image and the end of shooting of the moving image. 4. Optical equipment.   The switching means converts a command value of a target position calculation means for calculating a target position of the correction means when switching the detection accuracy of the position detection means, further controls parameters for controlling the appearance of the image, and the correction 5. The optical apparatus according to claim 1, wherein a gain for controlling the position of the means and a movable range of the correction means are changed. A correction unit that is disposed in the photographic lens and moves in a direction perpendicular to the optical axis of the photographic lens to correct blurring of an image formed by the photographic lens; and a shake detection unit that detects a shake of the optical device; The correction means based on position detection means for detecting a position of the correction means in a direction perpendicular to the optical axis, output from the shake detection means, and position information of the correction means detected by the position detection means. A method of controlling an optical apparatus comprising a drive control means for calculating a drive target value of
In the case where the switching unit captures a moving image and a still image using the optical device, the position is set so that the resolution is higher in the state of capturing the still image than in the state of capturing the moving image. When the detection accuracy of the detection means is switched and the detection accuracy of the position detection means is further switched, the drive center position of the correction means when shooting a moving image is changed to the drive center position of the correction means when shooting a still image. A method for controlling an optical apparatus, comprising:

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