JP2010224076A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress deterioration of detection accuracy of moving speed of a subject when an imaging apparatus sways. <P>SOLUTION: The imaging apparatus 100 includes: an image pickup device 2 which images an object; ranging means 13, 11 for detecting distance to the object; an operation means 11 for calculating the moving speed of the object based on first and second distance to the object under moving detected by the ranging means 13, 11 at first and second time, respectively and first and second image height of the object picked up at the first and second time by the image pickup device 2, respectively; detection means 19, 20 for detecting attitude change of the imaging apparatus 100 at the first and second time and for differentiating an orientation of an optical axis of a photography optical system 1 which forms a subject image to the image pickup device 2; and a control means 11 for controlling the operation means 11 so as to perform a correction operation according to the attitude change detected by the detection means 19, 20. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an imaging apparatus.

  A camera that detects the speed of a subject moving in a direction orthogonal to the optical axis is known (see Patent Document 1).

JP 2002-72059 A

  In the prior art, there is a problem that the measurement accuracy is poor when the subject moves in the optical axis direction of the camera or when the camera is held by hand.

  An image pickup apparatus according to the present invention includes an image pickup device for picking up an object, distance measuring means for detecting a distance to the object, and a moving object detected by the distance measuring means at the first time and the second time, respectively. The moving speed of the object is calculated based on the first distance and the second distance of the object, and the first image height and the second image height of the object imaged at the first time and the second time respectively by the image sensor. Calculating means, and detecting means for detecting a change in attitude of the imaging apparatus between the first time and the second time, wherein the attitude change of the optical axis of the imaging optical system for forming a subject image on the imaging element is different; And a control means for controlling the calculation means so as to perform a correction calculation according to the posture change detected by the detection means.

  In the imaging apparatus according to the present invention, it is possible to suppress a decrease in detection accuracy of the moving speed of the subject when the posture of the apparatus changes.

It is a figure which illustrates the relationship between a to-be-photographed object (moving object) and a camera. It is a block diagram explaining the structure of the electronic camera by one embodiment of this invention. It is a flowchart explaining the flow of a subject speed detection process.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. First, the principle of detecting the speed of a moving subject with a camera will be described with reference to FIG. FIG. 1 is a diagram illustrating the relationship between a subject (moving object) and a camera. In FIG. 1, a subject P is moving at a speed v in the camera direction along the optical axis Ax of the photographing lens of the camera.

  The camera measures the subject distance to the subject P at each of time t1 and time t2. The subject distance acquired at time t1 is D1, and the subject distance acquired at time t2 is D2. The angle between the light beam from the subject P and the optical axis Ax at time t1 is θ, and the angle between the light beam from the subject P ′ and the optical axis Ax at time t2 is θ ′.

When the focal length of the camera is f, the image height corresponding to the subject P is h1, and the image height corresponding to the subject P ′ is h2, the following equations (1) and (2) are established for the image heights h1 and h2.
h1 = f × tan θ (1)
h2 = f × tan θ ′ (2)

The component (distance x) in the optical axis Ax direction of the subject distance D1 is expressed by the following equation (3), and the component (distance y) in the optical axis Ax direction of the subject distance D2 is expressed by the following equation (4).
x = D1 × cos θ (3)
y = D2 × cos θ ′ (4)

The moving speed v in the optical axis direction of the subject P is expressed by the following equation (5).
v = (xy) / (t1-t2) (5)

  By calculating as described above, the moving speed v of the subject P in the optical axis direction is obtained. In FIG. 1, when the subject P exists above the center of the imaging range of the camera, the angles θ and θ ′ correspond to elevation angles. In addition, when the subject P exists below the center of the imaging range of the camera, the angles θ and θ ′ correspond to depression angles. Further, when the subject P exists to the left (or right) from the center of the imaging range of the camera, the angles θ and θ ′ correspond to azimuth angles. When the subject P is present at a position oblique to the center of the imaging range of the camera, the calculations for the elevation angle (the depression angle) and the azimuth angle are performed in combination.

  The configuration of a camera with a subject moving speed detection function using the above-described principle will be described below. FIG. 2 is a block diagram illustrating the configuration of the electronic camera 100 according to the embodiment of the present invention.

  In FIG. 2, the electronic camera 100 is controlled by the main CPU 11. The taking lens 1 forms a subject image on the image pickup surface of the image pickup device 2. The imaging device 2 is configured by a CCD image sensor or a CMOS image sensor, captures a subject image on the imaging surface, and outputs an imaging signal to the imaging circuit 3. The imaging circuit 3 performs analog processing (such as gain control) on the photoelectric conversion signal output from the imaging element 2 and converts the analog imaging signal into digital data by a built-in A / D conversion circuit.

  The main CPU 11 inputs a signal output from each block, performs a predetermined calculation, and outputs a control signal based on the calculation result to each block. The image processing circuit 12 is configured as an ASIC, for example, and performs predetermined image processing on the digital image signal input from the imaging circuit 3.

  The focus detection device 13 performs a known phase difference type focus detection calculation using a detection signal from a focus detection sensor (not shown). By this calculation, the focus adjustment state (defocus amount) by the photographing lens 1 is obtained, and the moving direction and the moving amount of the focus lens (not shown) constituting the photographing lens 1 are calculated according to the defocus amount. The movement amount information is sent to the main CPU 11.

  The lens driving mechanism 18 moves the focus lens forward and backward in the optical axis direction in response to an instruction from the main CPU 11.

  Further, the main CPU 11 obtains the subject distance to the main subject that is the focus detection target according to the defocus amount detected by the focus detection device 13. For example, by storing data indicating the relationship between the defocus amount and the subject distance in the flash memory 16 in advance, the subject distance is obtained with reference to the data.

  The display image creation circuit 14 generates a display signal for causing the liquid crystal monitor 22 to display a captured image, a menu screen, and the like. The liquid crystal monitor 22 includes a liquid crystal panel, and displays an image, an operation menu screen, and the like based on a display signal input from the display image creation circuit 14.

  The buffer memory 15 temporarily stores data before image processing, after image processing, and during image processing, and also stores an image file before being recorded on the recording medium 30 and an image file read from the recording medium 30. Used to remember.

  The flash memory 16 stores programs executed by the main CPU 11, data necessary for processing performed by the main CPU 11, and the like. The contents of the program and data stored in the flash memory 16 can be added or changed by an instruction from the main CPU 11.

  The card interface (I / F) 17 has a connector (not shown), and a recording medium 30 such as a memory card is connected to the connector. The card interface 17 writes data to the connected recording medium 30 and reads data from the recording medium 30 in accordance with an instruction from the main CPU 11. The recording medium 30 is configured by a memory card incorporating a semiconductor memory, a hard disk drive, or the like.

  The tilt sensor 19 generates a signal corresponding to the tilt angle of the electronic camera 100 (an angle when tilted in the pitch direction) and sends the signal to the main CPU 11. The inclination angle corresponds to the angle at which the optical axis Ax is inclined in the vertical direction. The angular velocity sensor 20 detects angular acceleration for detecting a shake generated in the electronic camera 100. For example, the angular acceleration generated in the pitch direction and the yaw direction of the electronic camera 100 is detected, and a detection signal is sent to the main CPU 11. The angular acceleration in the pitch direction corresponds to the vertical deflection of the optical axis Ax. The angular acceleration in the yaw direction corresponds to the horizontal shake of the optical axis Ax. The angular velocity sensor 20 is provided to realize a camera shake reduction function that reduces the swing of the subject image on the image sensor 2 caused by so-called camera shake. In this article, the details of the camera shake reduction processing are omitted.

  The operation member 21 includes various buttons and switches of the electronic camera 100 and outputs an operation signal according to the operation content of each operation member, such as a switching operation of a mode change switch, to the main CPU 11. The half-press switch 18a and the full-press switch 18b each output an ON signal to the main CPU 11 in conjunction with a pressing operation of a release button (not shown). The ON signal (half-press operation signal) from the half-push switch 18a is output when the release button is pushed down to about half of the normal stroke, and the output is released when the half-stroke push-down operation is released. The ON signal (full push operation signal) from the full push switch 18b is output when the release button is pushed down to the normal stroke, and the output is released when the normal stroke push down operation is released.

  FIG. 3 is a flowchart for explaining the flow of subject speed detection processing executed by the main CPU 11. For example, when an operation signal is input from a menu operation switch constituting the operation member 21, the main CPU 11 displays a menu operation screen for performing menu processing on the liquid crystal monitor 22. When an operation signal indicating an instruction to select a “speed measurement function on” item from the menu items is input from the operation member 21, the speed measurement function is turned on. The main CPU 11 repeatedly performs the process of FIG. 3 when the speed measurement function is on.

  In step S1 of FIG. 3, the main CPU 11 determines whether or not a half-press operation signal is input from the half-press switch 18a. When the half-press operation signal is input, the main CPU 11 makes a positive determination in step S1 and proceeds to step S2. If the half-press operation signal is not input, the main CPU 11 makes a negative determination in step S1 and repeats the determination process.

  In step S2, the main CPU 11 initializes detection information based on the angular velocity sensor 20 and detection information based on the tilt sensor 19 (zero point correction), and proceeds to step S3. Specifically, the rotation angles in both directions based on the angular acceleration detection signals in the pitch direction (up and down direction) and the yaw direction (left and right direction) are set to 0 degrees relative to each other, and the inclination angle α in the pitch direction based on the inclination detection signal is relatively 0 degrees. An angle (for example, an elevation angle) θ (θ ′) in FIG. 1 corresponds to an angle in the vertical direction.

  In step S <b> 3, the main CPU 11 captures and tracks the main subject from the subject image acquired by the image sensor 2, and causes the liquid crystal monitor 22 to display a frame indicating the main subject on the subject image. For example, a process of repeatedly capturing images by the image sensor 2, sequentially generating display images based on the acquired image signals, and reproducing and displaying the display images on the liquid crystal monitor 22 (live view display) is performed at predetermined time intervals (for example, , 30 frames / second).

  The main CPU 11 recognizes a specific image as the main subject P based on the image signal in the buffer memory 15 corresponding to each frame, and the position (position in the screen) and size (image) of the recognized subject P. Etc.) are specified. For the recognition of the subject, a technique such as template matching that calculates a similarity with a template image registered in advance and detects an image region having a similarity equal to or higher than a predetermined value as the position of the subject can be used. The main CPU 11 displays the above-described frame so as to overlap the display position of the recognized subject P.

  In step S4, the main CPU 11 detects the subject distance D1 and proceeds to step S5. Specifically, a focus detection region (focus detection position) that is a detection target of the defocus amount by the focus detection device 13 is set in correspondence with the recognized position of the subject P. The main CPU 11 obtains a subject distance D1 to the subject P according to the defocus amount detected by the focus detection device 13. The main CPU 11 stores the time t1 when the focus detection device 13 acquires the defocus amount. In addition, a series of operations are controlled so that imaging by the imaging device 2 is performed at time t1.

  In step S5, the main CPU 11 determines whether or not a full-press operation signal is input from the full-press switch 18b. When the full-press operation signal is input, the main CPU 11 makes a positive determination in step S5 and proceeds to step S6. When the full-press operation signal is not input, the main CPU 11 makes a negative determination in step S5, returns to step S2, and repeats the above-described processing.

  In step S6, the main CPU 11 determines whether or not the inclination angle α has changed. The main CPU 11 detects a change in the inclination angle α at times t1 and t2 based on the detection signal from the inclination sensor 19, and when the amount of change exceeds a predetermined value, the main CPU 11 makes an affirmative determination in step S6 and performs step S7. Proceed to When the change amount does not exceed the predetermined value, the main CPU 11 makes a negative determination in step S6 and proceeds to step S8.

In step S7, the main CPU 11 sets the angle (for example, the elevation angle) θ ′ in the above equation (4) to be corrected by the inclination angle α based on the detection signal of the inclination sensor 19 when calculating the moving speed v described later. Proceed to S8. Specifically, this corresponds to using the following equation (4 ′) instead of the above equation (4).
y = D2 × cos (θ′−Δα) (4 ′)
However, Δα is the difference between the inclination angles α at times t1 and t2.

  In step S8, the main CPU 11 detects the subject distance D2 and proceeds to step S9. The main CPU 11 sets a focus detection area (focus detection position) as a detection target of the defocus amount by the focus detection device 13 in correspondence with the position of the subject P ′ after movement. The main CPU 11 obtains a subject distance D2 to the subject P ′ according to the defocus amount detected by the focus detection device 13. The main CPU 11 stores the time t2 when the focus detection device 13 acquires the defocus amount. In addition, a series of operations are controlled so that imaging by the imaging device 2 is performed at time t2.

  In step S9, the main CPU 11 calculates the moving speed v based on the above equations (1) to (5), and proceeds to step S10. In addition, when going through step S7, the above equation (4 ′) is used. Here, the image heights h1 and h2 in FIG. 1 are calculated by the pixel pitch of the image sensor 2 × the number of pixels. The values of the pixel pitch and the focal distance f are stored in advance in the flash memory 16 as design information of the electronic camera 100.

  In step S10, the main CPU 11 displays the subject moving speed v calculated in step S9 on the liquid crystal monitor 22, and ends the process of FIG.

  In addition, when the electronic camera 100 shakes left and right (yaw direction) due to camera shake, the same correction can be performed in the horizontal direction in addition to the above-described correction in the vertical direction. However, a correction signal in the left-right direction uses a detection signal from the angular velocity sensor 20.

  In this case, the main CPU 11 determines whether or not the deflection angle β in the left-right direction has changed in step S6 of FIG. Based on the detection signal from the angular velocity sensor 20, the main CPU 11 detects a change in the lateral deflection angle β at times t1 and t2, and affirmatively determines step S6 if the amount of change exceeds a predetermined value. The process proceeds to step S7. When the change amount does not exceed the predetermined value, the main CPU 11 makes a negative determination in step S6 and proceeds to step S8.

In step S7, the main CPU 11 corrects the angle θ ′ (corresponding to the azimuth angle in the case of the left-right direction) θ ′ with the deflection angle β based on the detection signal of the angular velocity sensor 20 when calculating the moving speed v. Set so as to proceed to step S8. Specifically, this corresponds to using the following equation (4 ″) instead of the above equation (4).
y = D2 × cos (θ′−Δβ) (4 ″)
However, Δβ is the difference in yaw direction deflection angle β at times t1 and t2. The subsequent processing is the same as that in the case of vertical correction.

According to the embodiment described above, the following operational effects can be obtained.
(1) The electronic camera 100 includes an image sensor 2 that captures the subject P, which is an object, a distance measuring device (focus detection device 13, main CPU 11) that detects the distance to the subject P, and a distance measuring device at time t1. And the subject distances D1 and D2 to the moving subject P detected at time t2 and the image heights h1 and h2 of the subject P imaged at the time t1 and time t2 respectively by the image sensor 2. Of the optical axis Ax of the photographing lens 1 that forms a subject image on the image sensor 2, which is a change in posture of the electronic camera 100 at time t 1 and time t 2. Detected by a detection sensor (inclination sensor 19, angular velocity sensor 20) that detects a change in posture that changes the direction, and a detection sensor (inclination sensor 19, angular velocity sensor 20). Since the control circuit (main CPU 11) for controlling the arithmetic circuit (main CPU 11) so as to perform the correction calculation according to the change in the trend is provided, the subject P in the case where the posture of the electronic camera 100 is changed due to camera shake or the like. It is possible to suppress a decrease in the detection accuracy of the moving speed.

(2) The detection sensor includes a tilt sensor 19 that detects the tilt of the electronic camera 100, detects a tilt change of the electronic camera 100 that changes the imaging range of the image sensor 2 in the vertical direction, and an arithmetic circuit (main CPU 11). Since the correction calculation is performed using the inclination change, it is possible to suppress a decrease in the detection accuracy of the moving speed v of the subject P due to the vertical camera shake. Further, by using the tilt sensor 19, it is possible to suppress a decrease in detection accuracy to a smaller extent than when using an angular velocity sensor.

(3) The detection sensor includes an angular velocity sensor 20 that detects the shake of the electronic camera 100, detects a shake change of the electronic camera 100 that changes the imaging range of the imaging device 2 in the left-right direction, and an arithmetic circuit (main CPU 11). Since the correction calculation is performed using the shake change, it is possible to suppress a decrease in the detection accuracy of the moving speed v of the subject P due to the shake in the left-right direction.

(4) The arithmetic circuit (main CPU 11) calculates a distance x obtained by converting the subject distance D1 into a distance on the optical axis Ax and a distance y obtained by converting the subject distance D2 into a distance on the optical axis Ax. Since the quotient obtained by dividing the difference (x−y) between the distance y and the difference between the time t1 and the time t2 (t1−t2) is the moving speed v, it is not always necessary to capture the subject P at the center of the imaging range. Absent. Further, the detected moving speed can be compared with the moving speed of another subject.

(Modification 1)
In the above description, the configuration in which the obtained moving speed v is displayed on the liquid crystal monitor 22 and notified is exemplified. Instead of this, or in addition to this, data indicating the moving speed v may be recorded on the recording medium 30 together with the data of the photographed image.

  The above description is merely an example, and is not limited to the configuration of the above embodiment.

DESCRIPTION OF SYMBOLS 1 ... Shooting lens 2 ... Image sensor 11 ... Main CPU
DESCRIPTION OF SYMBOLS 13 ... Focus detection apparatus 19 ... Inclination sensor 20 ... Angular velocity sensor 21 ... Operation member 22 ... Liquid crystal monitor 100 ... Electronic camera

Claims (4)

An image sensor for imaging an object;
Ranging means for detecting the distance to the object;
The first and second distances to the moving object detected by the distance measuring unit at the first time and the second time, respectively, and the first and second times are imaged by the image sensor. Calculating means for calculating the moving speed of the object based on the first image height and the second image height of the object;
Detecting means for detecting a change in posture of the imaging apparatus between the first time and the second time, wherein the posture of the imaging optical system that forms a subject image on the image sensor is changed.
An imaging apparatus comprising: a control unit that controls the calculation unit so as to perform a correction calculation according to the posture change detected by the detection unit. The imaging device according to claim 1,
The detection means includes a tilt sensor that detects a tilt of the imaging device, detects a tilt change of the imaging device that changes an imaging range of the imaging device in the vertical direction,
The said calculating means performs the said correction calculation using the said inclination change, The imaging device characterized by the above-mentioned. The imaging device according to claim 1 or 2,
The detection means includes a shake sensor that detects a shake of the imaging device, detects a shake change of the imaging device that changes an imaging range of the imaging element in a left-right direction,
The image pickup apparatus, wherein the calculation means performs the correction calculation using the shake change. In the imaging device according to any one of claims 1 to 3,
The computing means calculates a third distance obtained by converting the first distance into a distance on the optical axis, and a fourth distance obtained by converting the second distance into a distance on the optical axis, and the third distance. And an quotient obtained by dividing the difference between the fourth distances by the difference between the first time and the second time is defined as the moving speed.

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