JP5631063B2 - Tilt detection device, shake correction device, imaging device, and tilt detection method thereof - Google Patents

Description

  The present invention relates to an inclination detection device, a shake correction device, an imaging device, and a control method thereof, and more particularly to a technique for determining the level of the imaging device.

  2. Description of the Related Art An image pickup apparatus is known that is equipped with a level and has a function of notifying a photographer of the level of an image to be photographed in order to obtain a horizontal composition. For example, when photographing a person against the background of a building, even a slight inclination of the composition is often noticeable. In such a case, it is possible to perform photographing while maintaining level by performing photographing while checking the level with a level. Or, if you want to add an angle to the composition on purpose, the spirit level is a guideline and is often used to assist the photographer.

  Patent Document 1 discloses a method in which the level of an imaging device is detected, and this information is used by a photographer as an assist for photographing. Patent Document 2 discloses a method for improving the accuracy of posture determination by correcting a vertical integration error that occurs when calculating the posture of an imaging device based on the output of an angular velocity detection means. Patent Document 3 discloses a method of calculating a rotation radius from the output of an angular velocity sensor and the output of an acceleration sensor, and simultaneously correcting two types of shakes of rotation shake and parallel shake using the calculated rotation radius. ing.

JP 2002-271654 A JP 2002-090116 A JP 2010-025961 A

  However, when performing hand-held shooting using an imaging device equipped with a level, or when shooting while panning using a tripod, the level cannot be maintained correctly due to the effects of camera shake and panning shake. There is. Generally, a level built in an imaging apparatus determines the level by detecting a change in gravity applied to the imaging apparatus. A change in gravity applied to the imaging device is detected using an acceleration sensor. The output of the acceleration sensor changes according to the change in acceleration. Such an acceleration sensor detects components other than gravity, such as a shake that causes a change in direction, such as a camera shake, or a panning operation that involves a change in direction because it includes a stop even at a constant speed. It will be. For this reason, the level may not be able to determine the correct levelness due to camera shake or panning operation.

  Accordingly, an object of the present invention is to provide an imaging apparatus capable of performing a highly accurate determination of the level even when a camera shake, a panning operation, or the like is added.

One aspect of the present invention relates to an inclination detection device, angular velocity detection means for detecting an angular velocity of a shake applied to the device, acceleration detection means for detecting the acceleration of the shake, angular velocity detected by the angular velocity detection means, and the acceleration. based on the detected acceleration by the detection means, and the roll rate calculating means for calculating a rocking Re velocity, and acceleration detected by the acceleration detecting means, based on the speed calculated by the roll rate calculating means, Of the accelerations detected by the acceleration detection means, shake component removal means for calculating gravitational acceleration, and determination means for determining the level of the inclination detection device based on the gravitational acceleration calculated by the shake component removal means. It is characterized by having.

  According to the above-described configuration, erroneous determination of the level due to the influence of shaking accompanying a change in acceleration due to camera shake or panning operation applied to the imaging apparatus is reduced, and it is possible to notify the photographer of high accuracy levelness. Therefore, according to the present invention, it is possible to provide an imaging apparatus capable of performing high-precision level determination even when a camera shake, a panning operation, or the like is added.

The block diagram which shows the structure of the level determination part of the imaging device in embodiment. 1 is a block diagram illustrating a configuration of an imaging device according to an embodiment. FIG. 6 is a diagram for explaining an example of shaking applied to the imaging apparatus according to the embodiment. The figure explaining the horizontal determination in embodiment. The flowchart of the levelness determination process in embodiment. The flowchart of the levelness determination process in embodiment.

  FIG. 2 is a block diagram illustrating a configuration of the imaging apparatus 1. The zoom unit 201 constituting the imaging optical system includes a zoom lens capable of zooming. The zoom drive control unit 202 controls driving of the zoom unit 201. The shift lens 203 is a correction member as a correction optical system that corrects image blur of an optical image formed by the imaging optical system. Specifically, the position of the shift lens 203 on a plane substantially perpendicular to the optical axis is changed. Is possible. The shift lens drive control unit 204 controls the drive of the shift lens 203 as a correction control unit. In this embodiment, the shift lens drive control unit 204 further functions as a horizontality determination processing unit that determines the level of the imaging apparatus 1 and provides a function as a level. An aperture / shutter unit 205 is controlled by an aperture / shutter drive control unit 206. The focus unit 207 includes a lens that performs focus adjustment. A focus drive control unit 208 controls driving of the focus unit 207. The imaging unit 209 includes an imaging element, and converts an optical image that has passed through each lens group into an electrical signal. The imaging signal processing unit 210 converts the electrical signal output from the imaging unit 209 into a video signal. The video signal processing unit 211 processes the video signal output from the imaging signal processing unit 210 according to the application.

  The display control unit 213 performs display control of the image obtained by the video signal processing unit 211. The display unit 214 performs image display as necessary based on the signal output from the display control unit 213. The power supply unit 215 supplies power to the entire system according to the application. The operation unit 216 is a user interface for operating the imaging apparatus. The storage unit 217 stores various data such as video information. The control unit 212 controls the entire system. The imaging device 1 further includes an angular velocity detection unit 100 that detects the angular velocity of the shake applied to the imaging device 1 and an acceleration detection unit 106 that detects the acceleration of the shake applied to the imaging device 1.

  Next, an example of shaking applied to the imaging device 1 will be described with reference to FIG. As described above, the imaging apparatus 1 includes the angular velocity detection unit 100 and the acceleration detection unit 106. At the time of shooting, the image pickup apparatus 1 can be shaken in the vertical direction indicated by the arrow P. In FIG. 3, reference numeral 301 denotes a center of rotation of a swing that draws an arc applied to the imaging apparatus 1. Let L be the distance from the rotation center 301 to the acceleration detection unit 106 (ie, the rotation radius). The rotation angle is θ. The angular velocity detection unit 100 and the acceleration detection unit 106 detect such shaking applied to the imaging device 1. At this time, the acceleration detection unit 106 also detects a change in gravity.

FIG. 1 shows the configuration of the shift lens drive control unit 204. The angular velocity detected by the angular velocity detector 100 is expressed as ω _{S + N} (t). This indicates that the angular velocity is an analog continuous function with time t (t is a positive real number) as a variable. The subscript S represents a shaking component, and N represents a detection noise component. In other words, the angular velocity detected by the angular velocity detection unit 100 includes a noise component in addition to the shaking component applied to the imaging device 1.

An analog signal representing the angular velocity detected by the angular velocity detector 100 is converted into digital data by the AD converter 101. That is, ω _{S + N} (t), which is an analog continuous function, becomes ω _{S + N} (n), which is a discrete function. Here, n is a natural number representing a discrete sample time.

A BPF 102 serving as a first band pass filter is provided at the subsequent stage of the AD converter 101. The BPF 102 is a filter that passes only a predetermined frequency band assumed for the vibration applied to the imaging apparatus 1. In general, an angular velocity sensor or an acceleration sensor includes white noise at the time of detection, and therefore, a BPF that allows only a necessary frequency component to pass through is widely used in order to eliminate the influence of the subsequent calculation. Further, since the hand shake component is generally 1 Hz to 10 Hz, the pass band is set to 1 Hz to 10 Hz, for example. Other frequency components are suppressed. Therefore, the angular velocity that is the output signal of the BPF 102 is ω _S (n) after the noise component N is removed. The integrator 103 integrates the angular velocity output from the BPF 102 to obtain a swing angle θ _S (n).

The cancellation amount calculation unit 104 calculates a cancellation amount y _S (n) for canceling the swing angle. The PID control unit 105 performs feedback control for driving the shift lens 203. That is, the PID control unit 105 sends a command to the drive unit 115 based on the cancel amount y _S (n), and performs control to move the shift lens 203 in the direction opposite to the shake.

The acceleration detected by the acceleration detection unit 106 is expressed as a _{S + M + N} (t). This indicates that the acceleration is an analog continuous function with time t as a variable. The subscript M represents a gravity component. That is, the acceleration detected by the acceleration detection unit 106 includes a noise component and a gravity component in addition to the shaking component applied to the imaging device 1.

An analog signal representing the acceleration detected by the acceleration detection unit 106 is converted into digital data by the AD converter 107. That is, a _{S + M + N} (t), which is an analog continuous function, becomes a _{S + M + N} (n), which is a discrete function.

A BPF 108 as a second bandpass filter is provided at the subsequent stage of the AD converter 107. The configuration and function are the same as those of the BPF 102. Therefore, the acceleration which is the output signal of the BPF 108 is a _{S + M} (n) with the noise component removed. The integrator 109 integrates the acceleration output from the BPF 108 to obtain a velocity v _{S + M} (n).

  The rotation radius calculation unit 110 calculates the distance from the rotation center 301 to the acceleration detection unit 106, that is, the rotation radius L. As a method for calculating the rotation radius L, for example, the method described in Patent Document 3 can be used. In the following, the method will be shown conceptually.

The relationship between the velocity v _{S + M} (n), the angular velocity ω _S (n), and the turning radius L is expressed by the following equation.
v _{S + M} (n) = L · ω _S (n) (1)
From this relationship, L is expressed by the following equation.
L = α · v _{S + M} (n) / ω _S (n) (2)
However, α is a correction constant that is multiplied for the purpose of reducing the influence of gravity included in the velocity v when the rotation radius L is calculated. This correction constant is a parameter determined by tuning.

The shaking speed calculation unit 111 calculates a speed at which the shaking component becomes dominant according to the following equation.
v _S (n) = L · ω _S (n) (3)

The shaking component removal unit 112 removes the shaking component included in the acceleration component from the acceleration a _{S + M} (n) including the shaking component and the gravity component. Specifically, as shown in the following equation, the value obtained by differentiating the velocity in which the shaking component calculated by the equation (3) is dominant is subtracted from the acceleration a _{S + M} (n).
a _S (n) = a _{S + M} (n) −D _n v _S (n) (4)
However, D _n represents differentiation by n. Thereby, the acceleration (gravity acceleration) of only the gravity component is obtained.

  The level determination unit 113 determines the level of the imaging device 1 based on the acceleration of only the gravity component obtained by the equation (4). Determination processing by the horizontal determination unit 113 will be described with reference to FIG. As shown in FIG. 4A, the level of the output of the acceleration detection unit 106 changes due to the change in the level of the imaging device 1. This is because the gravity always detected by the acceleration detection unit 106 changes when the level changes. If this level is within the area between the broken lines, it is determined to be horizontal. However, conventionally, as shown in FIG. 4A, a component of shaking accompanied by acceleration has been superimposed. For this reason, there is a problem that the horizontal determination result frequently fluctuates due to the superimposed shake component even in a region where the level of the imaging apparatus 1 does not substantially change. On the other hand, when the shaking component is removed as described above, as shown in FIG. 4B, the horizontal determination result does not change frequently, and the photographer can be informed of a highly accurate level. .

  The frequency determination unit 114 determines the vibration frequency from the output data of the angular velocity detection unit 100. This will be described later.

  Hereinafter, an example of the levelness determination process by the shift lens drive control unit 204 functioning as the levelness determination processing unit will be described with reference to the flowchart of FIG. Note that the angular velocity detection unit 100 can detect shaking in the vertical direction (also referred to as PITCH) of the imaging apparatus 1 and shaking in the lateral direction (also referred to as YAW) of the imaging apparatus 1, but the same flowchart is applied in each direction. Since it can, only one direction will be described. The same applies to the acceleration detection unit 106.

  In S501, the levelness determination process is started. This levelness determination process may be started when the power of the imaging apparatus 1 is turned on, or may be started when the release button is pressed. In step S <b> 502, a value obtained by converting analog data, which is shake information detected by the angular velocity detection unit 100, into digital data via the AD converter 101 is acquired. In S503, the shaking data acquired in S502 is filtered by the BPF 102. The initial value of the cut-off frequency of the BPF is normally set to transmit 1 Hz to 10 Hz, which is a camera shake band, but can be finely adjusted by tuning.

  In parallel with the acquisition of angular velocity in S502, acceleration is also acquired (S504). In S504, a value obtained by converting the analog data detected by the acceleration detection unit 106 into digital data via the AD converter 107 is acquired. In S505, the data acquired in S504 is filtered by the BPF 108. The initial value of the cutoff frequency of the BPF here is basically the same as that of the BPF 102.

  In S506, the integrator 109 integrates the acceleration to calculate the speed. This is because the rotation radius calculation unit 110 calculates the distance L from the rotation center 301 to the acceleration detection unit 106, that is, the rotation radius. In S507, the turning radius calculation unit 110 calculates the turning radius according to the equation (2). As described above, the equation (2) is multiplied by the correction coefficient α, which is a parameter determined by tuning. As an example of the tuning method, a predetermined shake is forcibly applied to the imaging apparatus, the value of this correction coefficient is swung back and forth, and the value when the shake component is most removed from the acceleration component is determined as the correction coefficient. it can.

  In S508, the shaking speed calculation unit 111 calculates the shaking speed according to the equation (3). Since the angular velocity used when calculating here is the output of S503, the shaking component is dominant. In S509, the shaking component removal unit 112 differentiates the shaking speed calculated in S508, and obtains a difference from the acceleration that is the output of S505. As a result, the gravitational component is dominant in the acceleration, and the preparation for making the horizontal determination without the influence of the shaking is completed as shown in FIG.

  In S510, the horizontal determination unit 113 determines whether or not the acceleration calculated in S509 is within a predetermined range. When it is within the predetermined range, it is determined to be horizontal (S511). If it is out of the predetermined range, it is determined that it is not horizontal (S511). Note that the horizontal level is not a binary value indicating whether or not it is horizontal, but it is also possible to inform the photographer of more detailed information on the level of horizontality. In step S513, the horizontality determination process ends.

  Note that, when the imaging apparatus is performing a panning operation, that is, when the imaging apparatus 1 is operating in one horizontal direction, it is possible to remove only the vertical (PITCH) vibration of the angular velocity detection unit 100. . By doing so, no erroneous determination is caused in the horizontal direction (the direction in which the panning operation is performed).

  FIG. 6 shows a modification example related to the levelness determination processing. This is a flowchart in which processing for performing frequency determination is added to the flow of FIG. The same processing steps as the processing steps shown in FIG. In FIG. 6, after S502 and S504, the frequency determination unit 114 determines the frequency of shaking from the output data of the angular velocity detection unit 100 (S601). Various methods for determining the frequency can be used. For example, a method of counting the number of zero crossings can be used. In S602, the cutoff frequencies of the BPF 102 and the BPF 108 are determined according to the determined frequency. Thereby, it is possible to adjust the pass band of the BPF in accordance with the distribution of the camera shake band of the photographer.

(Modification)
In the above embodiment, the calculation result of the rotation radius calculation unit 110 is used for the horizontal determination. However, it is also possible to correct both the rotational component of the shake applied to the imaging device and the shift component by using it for shake correction of the imaging device. (Dotted line arrow from the rotation radius calculation unit 110 to the cancellation amount calculation unit 104 in FIG. 1) The principle of shift component shake correction using the rotation radius is disclosed in, for example, Japanese Patent Application Laid-Open No. 2010-025961.

In this case, the cancellation amount calculation unit 104 applies the rotation radius L calculated by the rotation radius calculation unit 110 to the swing angle θ _S (n) obtained by the integrator 103, thereby causing the imaging apparatus 1 to The shift component of the applied shaking can be calculated. The cancel amount calculation unit 104 calculates a swing angle corresponding to the rotational component of the swing applied to the imaging apparatus 1 and a cancel amount y _S2 (n) for canceling the calculated shift component. Then, the drive unit 115 performs shake correction by moving the shift lens 203 in a direction opposite to the shake in accordance with the calculated cancellation amount y _S2 (n).

(Other examples)
As described above, the preferred embodiment of the present invention has been described by taking the imaging apparatus as an example. However, an electronic apparatus, a shake correction apparatus, or an optical apparatus such as a single lens reflex lens having a tilt detection apparatus having the above-described configuration. It may be. In particular, in the case of an optical apparatus having a shake correction device or a shake correction function, it is possible to use both a shake detection sensor and a tilt detection sensor.

  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.

Claims (9)

A tilt detection device,
Angular velocity detection means for detecting the angular velocity of shaking applied to the device;
Acceleration detecting means for detecting acceleration of the shaking;
And roll rate calculating means based on the detected by the detected angular velocity and the acceleration detection unit acceleration, calculates the rocking Re speed by the angular velocity detecting means,
Based on the acceleration detected by the acceleration detecting means and the speed calculated by the shaking speed calculating means, a shaking component removing means for calculating a gravitational acceleration among the accelerations detected by the acceleration detecting means;
Determining means for determining the level of the inclination detecting device based on the gravitational acceleration calculated by the shaking component removing means;
An inclination detection apparatus comprising:   The shaking component removing means subtracts a value obtained by differentiating the speed calculated by the shaking speed calculating means from the acceleration detected by the acceleration detecting means, thereby obtaining the acceleration detected by the acceleration detecting means. The inclination detection apparatus according to claim 1, wherein the acceleration of only the gravity component is calculated.   The tilt detection apparatus according to claim 1, wherein when the tilt detection apparatus is performing a panning operation, only the vertical component of the shaking is detected. To provided after the angular velocity detecting means, of the output of said angular velocity detecting means, a first band pass filter for passing only a predetermined frequency band which is assumed for the shake,
Provided after the acceleration detecting means, of the output of said acceleration detecting means, the second band pass filter that passes only predetermined frequency band,
The tilt detection apparatus according to claim 1, further comprising: Frequency determining means for determining the frequency of the shaking;
Adjusting means for adjusting the passbands of the first and second bandpass filters according to the frequency determined by the frequency determining means;
The inclination detection apparatus according to claim 4, further comprising: An inclination detection apparatus according to any one of claims 1 to 5,
A correction member that corrects image shake of an optical image formed by the imaging optical system;
And correction control means for driving the correction member based on the angular velocity detected by said angular velocity detecting means,
A shake correction apparatus comprising: The shake correction apparatus according to claim 6;
Display means for displaying the level of the inclination detecting device determined by the determining means;
An imaging device comprising: An inclination detection apparatus according to any one of claims 1 to 5,
A correction member that corrects image shake of an optical image formed by the imaging optical system;
And correction control means for driving the correction member based on the angular velocity detected by said angular velocity detecting means,
Display means for displaying the level of the inclination detecting device determined by the determining means;
An imaging device comprising: An imaging apparatus tilt detection method comprising:
An angular velocity detection step of detecting an angular velocity of shaking applied to the imaging device;
An acceleration detection step of detecting acceleration of the shaking;
Based on the angular velocity detection step acceleration detected by the detected angular velocity and the acceleration detection step by a roll rate calculating process of calculating a rocking Re velocity,
Based on the acceleration detected by the acceleration detecting step and the velocity calculated by the shaking velocity calculating step, a shaking component removing step of calculating gravitational acceleration among the accelerations detected by the acceleration detecting step;
A determination step of determining the level of the imaging device based on the gravitational acceleration calculated by the shaking component removal step;
An inclination detection method for an imaging apparatus, comprising:

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