JP2019095630A - Optical instrument having image tremor correction device - Google Patents

Abstract

To make it possible to easily take effective panning photos.SOLUTION: An optical instrument having an image tremor correction device has: motion vector detection means that detects a movement speed of a subject in a photographing screen of a camera; offset calculation means that calculates an offset component of an angle velocity sensor 135 from the angle velocity sensor 135 and a signal of the motion vector detection means at a time when it is determined by panning determination means that the camera is not set to a panning state, and when tremor correction means is held at a prescribed position; and panning reference speed calculation means that, with a signal subtracting the offset component calculated by the offset calculation means from the angle velocity sensor 135 as a second tremor detection signal, calculates a panning reference speed of the camera from the second tremor detection signal and the signal of the motion vector detection means when it is determined by the panning determination means that the camera is panned. During exposure, on the basis of a difference between the panning reference speed and the second tremor detection signal, the tremor correction means is actuated to correct image tremors.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an imaging apparatus capable of easily realizing a follow shot technique which requires skill, in an imaging apparatus which improves the accuracy of a photographed image by detecting and correcting camera shake.

  In order to correct the image blur generated due to the influence of camera shake or the like generated in the camera, the vibration of the camera is detected, and the correction lens or the image sensor is moved according to the detection result to change the optical axis. Detection of camera vibration is basically a shake sensor for detecting angular acceleration, angular velocity, etc., and a means for electrically or mechanically integrating the output signal of the shake sensor and outputting angular displacement as the camera It can be done by mounting. Then, it has been proposed that the correction optical system for decentering the photographing optical axis is driven based on the detected information, and the position of the correction optical system is detected to perform feedback control, whereby accurate image blurring can be suppressed. (E.g., Patent Document 1).

  Also, one of the shooting methods with a camera is panning. This is a method of shooting while causing the camera to follow the movement of the main subject moving in the horizontal direction, for example. With a good follow-up photo, the main subject is stationary on the photo, and the background is the main subject. It is a photograph flowing in the moving direction. At this time, it is common to shoot at a slow shutter speed in order to make the subject feel dynamic. It is necessary to have experience to make the camera follow the movement of the subject accurately, and the shutter speed is slow, so it is prone to shake, and it is a relatively difficult shooting technique for beginners.

  Therefore, Patent Document 2 proposes a method for assisting the follow shot by using a correction optical system. As a specific method, the moving speed of the main subject on the imaging surface is detected, and the main subject moving angular velocity is calculated from the difference from the follow-up speed performed by the photographer. During exposure, the difference between the calculated main object movement angular velocity and the follow shot angular velocity performed by the photographer, that is, the follow shot angular velocity error is detected. By making the optical eccentricity so as to correct the error, the photographer is supposed to be able to take a beautiful follow-up photograph.

  Here, when calculating the subject moving speed, it is important to accurately remove the offset of the angular velocity sensor. In order to detect the offset, there is a method in which the offset component is extracted by setting the stationary state so that the vibration is not input to the angular velocity sensor. Patent Document 3 discloses, as a method of eliminating an offset of an angular velocity sensor, acquiring a shake signal of an object image by an AF sensor, and estimating and eliminating the offset of the angular velocity sensor.

Unexamined-Japanese-Patent No. 7-218967 gazette Japanese Patent Application Publication No. 2007-139952 JP 2001-356380 A

  In order to detect the offset, having the photographer perform the process of putting the camera in a stationary state before taking a picture is a burden for the photographer and it is difficult to do so when it is desired to take a picture quickly.

  The invention disclosed in Patent Document 3 discloses the contents of performing offset adjustment of an angular velocity sensor signal processing circuit based on an image blur signal from an AF sensor after the start of energization of the angular velocity sensor. However, the driving state of the image blur correction lens and the processing of the image blur signal after the offset adjustment are not disclosed. Depending on the operation state of the image blur correction lens, the image blur signal and the signal of the angular velocity sensor are not synchronized, and it is difficult to accurately adjust the offset.

In order to solve the above-mentioned problems, according to the invention described in claim 1 in the present application,
Shake detection means for detecting camera shake;
Let the signal of the shake detection means be a first shake detection signal,
Motion vector detection means for detecting the moving speed of the subject within the shooting screen of the camera;
Shake correction means capable of correcting the shake of a subject image by decentering the optical axis of the shooting lens;
Panning determination means for determining whether the camera is panned;
From the first shake detection signal and the signal from the motion vector detection means when it is determined that the panning determination means does not perform panning and the shake correction means is held at a predetermined position, Offset calculation means for calculating an offset component of the first shake detection signal;
A signal obtained by subtracting the offset component calculated by the offset calculation means from the first shake detection signal is taken as a second shake detection signal,
Having a panning reference speed computing means for calculating a panning reference speed of the camera from the second shake detection signal and the signal of the motion vector detection means when it is determined that the panning is judged by the panning judgment means; It features.

Further, in order to solve the above-mentioned problems, according to the invention described in claim 2 in the present application,
Shake detection means for detecting camera shake;
Let the signal of the shake detection means be a first shake detection signal,
Motion vector detection means for detecting the moving speed of the subject within the shooting screen of the camera;
Shake correction means capable of correcting the shake of a subject image by decentering the optical axis of the shooting lens;
Panning determination means for determining whether the camera is panned;
From the first shake detection signal and the signal from the motion vector detection means when it is determined that the panning determination means does not perform panning and the shake correction means is held at a predetermined position, Offset calculation means for calculating an offset component of the first shake detection signal;
A signal obtained by subtracting the offset component calculated by the offset calculation means from the first shake detection signal is taken as a second shake detection signal,
Panning reference speed calculation means for calculating a panning reference speed of the camera from the second shake detection signal and the signal of the motion vector detection means when it is determined that panning is performed by the panning determination means;
During exposure, the image pickup apparatus further comprises shake correction control means for driving the shake correction means based on a difference between the panning reference speed and the second shake detection signal.

  According to the present invention described above, the offset component of the shake detection means is calculated from the motion vector signal while the shake correction means is held at the predetermined position. Then, by calculating the panning reference speed, that is, the follow shot reference angular velocity, from the shake detection signal from which the offset component is subtracted and the motion vector signal, it is possible to calculate the correct follow shot reference speed. Then, during exposure, the follow shot angular velocity error is calculated from the difference between the detected follow shot reference velocity and the angular velocity obtained by subtracting the offset component from the signal of the shake detection means, and the calculated angular velocity error is corrected. By doing this, it is possible to accurately correct the subject shake during panning.

It is a block diagram showing the camera system of this invention. It is a figure showing the photography method at the time of the panning photography of this invention. It is a figure showing each signal waveform at the time of the follow shot imaging | photography of this invention. It is a figure showing each signal waveform at the time of the follow shot imaging | photography of this invention. It is a flowchart which shows operation | movement of the camera of this invention. It is a flowchart which shows operation | movement of the interchangeable lens of this invention. It is a flowchart which shows operation | movement of image blurring correction of this invention.

  Hereinafter, the present invention will be described in detail based on the illustrated embodiments.

[Example]
Hereinafter, the configuration of a camera system according to an embodiment of the present invention will be described with reference to FIG. The camera system comprises a camera body 111 and an interchangeable lens 112. The imaging light flux from the subject passes through the imaging optical system of the interchangeable lens 112 and forms an image on the imaging unit 113. The formed image is photoelectrically converted by the imaging unit 113 to be an imaging signal. The imaging signal is amplified by the gain control circuit 115, input to the A / D converter 116, and converted from analog to digital image data.

  A video signal processing circuit 117 performs filter processing, color conversion processing, gamma processing, and the like on the image data digitized by the A / D converter 116. The motion vector of the subject image is calculated by the video processing circuit 117. The image signal processed by the image signal processing circuit 117 is stored in the buffer memory 118 and displayed on the LCD 119 or recorded in the removable memory card 120.

  The operation unit 121 is a switch for setting the shooting mode of the camera, setting the size of the recorded image file, and releasing at the time of shooting. The camera system control MPU 114 controls the above-described operation of the camera body 111 and communicates with the lens MPU 124 via the interface circuit 122 on the camera body 111 side and the interface circuit 123 on the interchangeable lens 112 side. In this communication, various data are exchanged between the digital camera body 101 and the interchangeable lens 102.

  In the interchangeable lens 102, a focus lens 125, a zoom lens 126, an image blur correction lens 127, and a stop 128 are disposed as a part of the photographing optical system. The focus lens 125 is driven by the control signal from the lens MPU 124 via the focus control circuit 129 and the focus lens drive motor 130. The focus control circuit 129 includes, in addition to the focus lens drive circuit, a focus encoder that outputs a zone pattern signal and a pulse signal according to the movement of the focus lens. The subject distance can be detected by this focus encoder.

  The zoom lens 126 is moved by the photographer operating a zoom operation ring (not shown). The zoom encoder 131 outputs a zone pattern signal according to the movement of the zoom lens. The photographed image magnification is obtained by the lens MPU 124 reading signals from the focus encoder and the zoom encoder 131 and reading photographed image magnification data stored in advance by a combination of the subject distance and the focal distance.

  The image blur correction lens 127 is driven via the image blur correction control circuit 132 and the linear motor 133. Image blur correction is performed as follows. That is, the shake signal of the angular velocity sensor 135 that detects rotational shake is processed by the signal processing circuit 136 and input to the lens MPU 124. The lens MPU 124 calculates a correction lens drive target signal, and outputs a drive signal according to the difference between the correction lens drive target signal and the correction lens position signal output from the correction lens encoder 134 to the image blur correction control circuit 132 .

  The image blur correction is performed by feeding back the correction lens position signal output from the correction lens encoder 134 to the image blur correction control circuit 132 as described above. The above-described image blur correction control is performed on each of two axes of a pitch axis for detecting an inclination in the vertical direction and a yaw axis for detecting an inclination in the horizontal direction with the camera body 101 as a center.

  The diaphragm 128 is driven by a control signal from the lens MPU 124 via the diaphragm control circuit 137 and the stepping motor 138. A switch 139 is a switch for selecting the image blur correction ON / OFF and the image blur correction operation mode. The image blur correction mode can select a normal image blur correction operation and a follow shot operation mode.

  Next, the follow shot method of the present invention will be described with reference to FIGS. FIG. 2 shows the movements of the subject and the camera in time series of (a) and (b) when the subject passing by in front of the eyes is photographed by the panning method. By moving the camera to match the moving speed of the subject during the exposure period, the movement of the subject is stopped, and it is possible to take a picture with the background flowing. However, if the photographer is unfamiliar with the camera, the camera may aim at the center C0 of the subject and shift the camera to C1 in FIG. 2B, for example, even if the camera is intended to be shaken according to the movement of the subject.

  As described above, FIG. 3 shows the output of the angular velocity sensor 135 and the waveform of the motion vector amount of the subject image detected by the video signal processing circuit 117 when the aim is shifted in the follow shot photographing. FIG. 3A shows an output waveform of the angular velocity sensor 135, and FIG. 3B shows a motion vector signal waveform. In FIG. 3A, if the subject speed is constant, the ideal follow-up angular velocity that the subject keeps following without shaking becomes a constant angular velocity as shown by a dotted line. If the subject is kept following without shaking, the motion vector of the subject in FIG. 3B is "0". However, it is difficult to accurately keep track of moving objects, and in fact, it deviates from the ideal follow shot angular velocity as shown by the solid line in FIG. 3 (a). The motion vector at this time also deviates from "0" as shown in FIG. 3 (b).

  Therefore, by driving the image shake correction lens 127 so as to correct the deviation from the ideal follow shot angular velocity, the shake of the subject can be corrected. As an actual photographing operation, an image blur correction lens 127 is driven to calculate a follow shot reference angular velocity before exposure and correct a deviation from the follow shot reference angular velocity during exposure.

  FIGS. 4A, 4B, and 4C show the output of the angular velocity sensor 135 from the timing t1 at which the shooting starts before the camera starts and the shooting starts, the timing t2 at which the exposure starts, and the timing t3 at which the exposure ends. A waveform, a motion vector signal waveform, and a position signal of the image blur correction lens 127 are shown.

  The output signal of the angular velocity sensor 135 shown in FIG. 4A has an offset component, and the output waveform up to the timing t1 before holding the camera and starting to shoot is a waveform in which a camera shake component is superimposed on the offset component. It becomes. The motion vector signal waveform of FIG. 4B becomes a waveform of a camera shake component until timing t1. This is because the image blur correction lens 127 in FIG. 4C is held at a fixed position, and a camera shake component appears as a motion vector as it is.

  Therefore, when the signals of FIGS. 4A and 4B are added, only the offset component of the angular velocity signal is extracted. Thereafter, when the follow shot is started at timing t1, the angular velocity signal largely changes. At this time, by subtracting the offset component of the angular velocity signal calculated up to the timing t1, an accurate angular velocity signal can be obtained, and in the calculation of the motion vector, discrimination of the main subject from the background and calculation of the motion vector of the main subject It can be done precisely. Therefore, it is possible to accurately calculate the follow shot reference angular velocity by the timing t2 at which the exposure is started.

  Then, during the period from the exposure start to the end, that is, the period from timing t2 to t3, the difference between the follow shot reference angular velocity and the angular velocity signal is integrated to calculate an angular displacement signal which is a follow shot error, and the difference is canceled. Thus, the image blur correction lens 127 is driven as shown in the waveform of FIG.

  By operating in this manner, the error of the follow shot is corrected, and a beautiful follow shot can be taken.

  The above operation will be described according to the flowcharts of FIG. 5 to FIG. First, the photographing operation of the camera body 1 will be described with reference to the flowchart of FIG. When the main switch is turned on on the camera body 1 side, the operation is started from step 501.

  (Step 501) It is determined whether the release switch on the operation unit 121 of the camera body 101 has been half-pressed (SW1 ON). If it is half-pressed, the process proceeds to step 502, and if it is not half-pressed, the processing here ends.

  (Step 502) Camera lens status communication is performed with the lens MPU 124 via the interface circuits 122 and 123. Here, the camera status (release switch status SW1 ON, shooting mode, shutter speed, etc.) is sent to the lens, or the lens status (focal length, aperture status, focus lens drive status, etc.) is received. . Although the camera lens status communication is described in only the main part in the flowchart of this embodiment, it is performed as needed when the camera state changes or when the camera wants to check the lens state.

  (Step 503) Since the release switch has been half-pressed (SW1 ON), the focus lens driving amount for focusing on the subject is calculated.

  (Step 504) The focus lens driving amount is transmitted to the interchangeable lens 112. This data is transmitted, for example, as a drive target pulse amount of the focus encoder.

  (Step 505) When driving of the focus lens is completed, re-ranging is performed.

  (Step 506) It is determined whether or not it is within the in-focus depth, and if within the in-focus depth, the process proceeds to Step 507.

  (Step 507) The angular velocity information reception data is read out.

  (Step 508) The main subject is determined from the image signal of the video signal processing circuit 117 in consideration of angular velocity information.

  (Step 509) Motion vector information of the main subject is detected.

  (Step 510) The detected motion vector information of the main subject is transmitted to the lens MPU 124.

  (Step 511) It is determined whether the release switch on the operation unit 121 of the camera body 111 is full-pressed (SW2 ON). If it is full-pressed, the process proceeds to step 512.

  (Step 512) The shutter speed and the aperture value are calculated by photometry, the diaphragm drive amount is transmitted to the interchangeable lens 112, and the diaphragm 128 is driven.

  (Step 513) The charge of the imaging unit 113 is reset, and the electronic shutter is driven.

  (Step 514) The image of the subject is exposed to the imaging unit 113 and the charge is accumulated.

  (Step 515) When the exposure time has elapsed, the trailing shutter not shown is driven to complete the exposure.

  (Step 516) The charge transfer (reading) from the imaging unit 113 is performed.

  (Step 517) The captured image signal read out is converted into digital data through the gain control circuit 115 and the A / D converter 116, and is stored in the buffer memory 118.

  (Step 518) A diaphragm open command is sent to the interchangeable lens 112, and the diaphragm 128 is returned to the open state.

  (Step 519) Image correction processing such as gamma correction and compression processing is performed on the photographed image signal.

  (Step 520) The image data subjected to the image correction processing is displayed on the LCD 119 and recorded on the memory card 120, and a series of operations up to photographing are completed.

  Next, the operation of the interchangeable lens 112 will be described according to the flowcharts shown in FIGS. 6 and 7. When the lens is attached to the camera, serial communication is made from the camera to the lens, and the operation of FIG. 6 is started.

  In serial communication processing, communication command data is decoded, and lens processing such as aperture driving and focus lens driving is performed according to the decoding result. Then, by decoding the communication data, it is possible to determine SW1 ON, SW2 ON, shutter speed, camera model, and the like. When the communication from the camera is received, the operation starts from step 601.

  At step 601, a command from the camera is analyzed, and the process branches to a process corresponding to each command. In step 602, since the focus drive instruction has been received, in step 603, the speed setting of the focus lens drive motor 130 is performed according to the target drive pulse number, and focus lens drive is started. In step 604, since the diaphragm drive instruction is received, the drive pattern of the stepping motor 138 is set in step 605 to drive the diaphragm 128 based on the transmitted diaphragm drive data, and the set drive pattern is controlled for diaphragm control. The signal is output to the stepping motor 138 via the circuit 137 to drive the diaphragm 128.

  At step 606, since the camera lens status communication has been received, at step 607, the focal distance information of the lens and the IS operation status etc. are transmitted to the camera, and the camera status status (release switch status, shooting mode, shutter speed etc) To receive).

  In step 608, since the instruction to transmit and receive the motion vector information and the angular velocity information is received, the motion vector information of the subject received in step 609 is stored in the RAM in the lens MPU 124. Also, angular velocity information is transmitted to the camera. This angular velocity information is angular velocity information from which the offset component has been removed. In step 610, other instructions such as lens focus sensitivity data communication, lens optical data communication, and the like are performed. In step 611, their processing is performed.

  Next, image shake correction processing will be described using the flowchart of FIG. 7. When an image blur correction interrupt occurs during the main operation of the lens, the lens MPU 124 starts control of the image blur correction from step 701 in FIG.

  (Step 701) The output signal obtained by processing the signal of the angular velocity sensor 135 by the signal processing circuit 136 is A / D converted.

  (Step 702) The state of the switch 139 is determined to determine whether it is a follow shot mode or a normal anti-shake mode, and if it is a normal anti-shake mode, the process proceeds to step 703, and if it is a follow shot mode Go to 706.

  (Step 703) A high pass filter operation is performed to cut low frequency components.

  (Step 704) The integration operation is performed with the operation result of the high pass filter as an input. The result is angular displacement data.

  (Step 705) The image stabilization sensitivity corresponding to the zoom position and the focus position is read out, and the target drive amount of the shake correction lens 127 is calculated from the angular displacement data.

  (Step 706) Since the follow shot mode is selected, it is determined whether SW2 is ON, that is, whether the exposure operation has been selected. If SW2 is OFF, the process proceeds to step 707. If SW2 is ON, the process proceeds to step 713.

  (Step 707) It is determined whether or not the follow shot operation is in progress. If the follow shot operation is not in progress, it is in a state before the start of the follow shot operation up to time t1 in FIG. If the follow shot operation is not in progress, the process proceeds to step 708. If the follow shot operation is in progress, the process proceeds to step 711.

  (Step 708) The angular velocity signal W1 and the vector information transmitted from the camera are added. At this time, the image blur correction lens 127 is held at a constant position of the target drive amount “0”.

  (Step 709) From the calculation result of step 708, the offset amount OFST of the angular velocity signal W1 is calculated and stored in the RAM area in the lens MPU 124.

  (Step 710) The target drive amount is set to 0 in order to electrically maintain the image blur correction lens 127 in the center state.

  (Step 711) Since it is determined in step 707 that the follow shot operation is being performed, the angular velocity signal W2 is calculated by subtracting the offset OFST from the angular velocity signal W1.

  (Step 712) The angular velocity signal W2 from which the offset has been eliminated is added to the motion vector V of the main subject during follow-up to calculate the follow-up reference angular velocity W0.

  (Step 713) Since the exposure operation is detected in Step 706, the follow shot angular velocity error WE is calculated from the difference between the follow shot reference angular velocity W0 and the angular velocity signal W2.

  (Step 714) The angular velocity error WE is integrated and calculated to calculate angular displacement data. This is the angular displacement data of the panning error.

  (Step 715) The image stabilization sensitivity corresponding to the zoom position and the focus position is read, and the target drive amount of the image blur correction lens 127 is calculated from the angular displacement data.

  (Step 716) The signal of the correction lens encoder 134 for detecting the amount of eccentricity of the image blur correction lens 127 is A / D converted, and the A / D result is stored in the RAM area in the lens MPU 124.

  (Step 717) A feedback operation is performed.

  (Step 718) A phase compensation operation is performed to obtain a stable control system.

  (Step 719) The calculation result of Step 718 is output as PWM to the port of the lens MPU 124, and the image blur correction interrupt is ended. The output is input to a driver circuit in the IS control circuit 132, and the image blur correction lens 127 is driven by the linear motor 133 to correct the image blur.

  As described above, before the follow shot operation is started, the offset component of the angular velocity sensor is calculated from the signals of the angular velocity sensor and the motion vector while holding the image shake correction lens at a predetermined position. Then, by calculating the motion vector of the main subject and the follow shot reference angular velocity using the angular velocity signal from which the offset has been subtracted, it is possible to obtain the follow shot reference angular velocity with high accuracy. Then, during exposure, an angular velocity error from the follow shot reference angular velocity with high accuracy is calculated, and the image blur correction lens is driven to correct the error. Therefore, it is possible to easily take a clear follow shot photograph.

  In the above embodiment, an example of a camera for observing an object image in live view shooting has been described. However, similar effects can be obtained if vector information of the object can be calculated by a photometric sensor disposed in an optical finder. You can get it.

  Further, in the above embodiment, an example in which the follow shot angular velocity is calculated on the interchangeable lens side has been described, but it may be calculated on the camera body side and data may be transmitted to the interchangeable lens side. Further, although the example of the interchangeable lens type camera system is shown in the above embodiment, it may be a camera lens integrated type or compact digital camera.

  Although the preferred embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the present invention.

111 Camera Body 112 Interchangeable Lens 113 Imaging Unit 114 Camera System MPU
117 image signal processing circuit 122 camera side interface circuit 123 lens side interface circuit 124 lens MPU
125 focus lens 126 zoom lens 127 shake correction lens 133 shake correction lens drive motor 134 shake correction lens encoder 135 angular velocity sensor

Claims (4)

Shake detection means for detecting camera shake;
Let the signal of the shake detection means be a first shake detection signal,
Motion vector detection means for detecting the moving speed of the subject within the shooting screen of the camera;
Shake correction means capable of correcting the shake of a subject image by decentering the optical axis of the shooting lens;
Panning determination means for determining whether the camera is panned;
From the first shake detection signal and the signal from the motion vector detection means when it is determined that the panning determination means does not perform panning and the shake correction means is held at a predetermined position, Offset calculation means for calculating an offset component of the first shake detection signal;
A signal obtained by subtracting the offset component calculated by the offset calculation means from the first shake detection signal is taken as a second shake detection signal,
Having a panning reference speed computing means for calculating a panning reference speed of the camera from the second shake detection signal and the signal of the motion vector detection means when it is determined that the panning is judged by the panning judgment means; An optical apparatus having an image blur correction device as a feature. Shake detection means for detecting camera shake;
Let the signal of the shake detection means be a first shake detection signal,
Motion vector detection means for detecting the moving speed of the subject within the shooting screen of the camera;
Shake correction means capable of correcting the shake of a subject image by decentering the optical axis of the shooting lens;
Panning determination means for determining whether the camera is panned;
From the first shake detection signal and the signal from the motion vector detection means when it is determined that the panning determination means does not perform panning and the shake correction means is held at a predetermined position, Offset calculation means for calculating an offset component of the first shake detection signal;
A signal obtained by subtracting the offset component calculated by the offset calculation means from the first shake detection signal is taken as a second shake detection signal,
Panning reference speed calculation means for calculating a panning reference speed of the camera from the second shake detection signal and the signal of the motion vector detection means when it is determined that panning is performed by the panning determination means;
An optical apparatus having an image shake correction device, comprising: an image shake correction control unit configured to drive the shake correction unit based on a difference between the panning reference speed and the second shake detection signal during exposure. The optical apparatus having the image shake correction apparatus according to claim 1 or 2, wherein the image shake correction control means does not perform the image shake correction when the exposure is not in progress. 3. The image shake according to claim 2, wherein the image shake correction control means integrates a difference between the panning reference speed and the second shake detection signal and performs shake correction according to an integration result. Optical apparatus having a correction device.