JP4974829B2 - Imaging device - Google Patents

Description

The present invention relates to an imaging apparatus.

  Most digital video cameras have optical zoom, electronic zoom, or both. There are many situations in which a digital video camera cannot be close to the subject, as can be seen when considering shooting at an athletic meet, one of the scenes where digital video cameras are often used. In such a scene, a high magnification zoom is useful. The equipped model is advantageous.

  The zoom function of the video camera includes an optical zoom and an electronic zoom. In the optical zoom, the focal length is changed by changing the zooming lens in the photographic lens in the optical axis direction, and the photographic angle of view is changed. On the other hand, in the electronic zoom, a part of the image signal of one screen is electronically extracted and enlarged to the original screen size to substantially change the shooting angle of view. In terms of image quality, optical zoom is superior to electronic zoom, and in terms of cost, electronic zoom is superior to optical zoom. Many video cameras are equipped with both optical zoom and electronic zoom.

  When shooting at a high magnification zoom, the angle of view (shooting range) is narrower than when the zoom magnification is low. Therefore, as schematically shown in FIG. 7, the image being photographed moves greatly due to slight movement of the video camera body. For this reason, in order to follow a subject that is moving at a high magnification zoom while keeping it within the photographing range, the photographer needs a suitable technique. In addition, when the video camera is shaken by an external impact and the subject is out of the shooting range, it is not easy to capture the subject again. If the subject is out of the shooting range, the photographer is forced to perform a troublesome operation of once capturing the subject after moving the zoom to the wide-angle side and returning it to the telephoto side again.

In order to solve such a problem, a technique has been proposed in which an enlarged image and a non-enlarged image can be selectively displayed on a viewfinder while recording an image enlarged by electronic zoom (see Patent Document 1). In this method, when the subject is lost, the non-enlarged image is switched to the finder display target, whereby the subject can be easily captured and the subject can be re-entered within the shooting angle of view. Zoom-out / zoom-in operations become unnecessary, and images magnified by electronic zoom are continuously recorded.
JP-A-11-289486

  The technique described in Patent Document 1 is applicable only when an electronic zoom is used, and a method applicable to optical zoom has been demanded.

  The present invention has been made in view of the above situation, and an object of the present invention is to provide an imaging apparatus that can easily capture a subject even when the subject is lost from the viewfinder due to an external impact.

Imaging device according to the present invention is an imaging apparatus having an imaging means for converting a photographic lens having's over beam function, the optical image of an object by the imaging lens into an image signal, detecting an acceleration of the imaging device an acceleration detecting means for, based on an output of the acceleration detecting means, when the blur in the photographed image is determined to have occurred by the imaging unit, have a control means for changing the photographing lens to the wide angle side, The control means increases the amount of change for changing the photographing lens to the wide-angle side as the focal length of the photographing lens increases .
Imaging device according to the present invention is an imaging apparatus having an imaging means for converting a photographic lens having's over beam function, the optical image of an object by the imaging lens into an image signal, detecting an acceleration of the imaging device An amount of movement of the imaging device is calculated from the output of the acceleration detection means , the acceleration detected by the acceleration detection means exceeds an acceleration threshold value, and the calculated amount of movement is the amount of movement if it exceeds the threshold, have a control means for changing the photographing lens to the wide angle side, the control means, as the focal length of the photographing lens is large, the change in order to change the imaging lens to the wide angle side It is characterized by increasing the amount .

  According to the present invention, when acceleration and movement corresponding to camera shake or external vibration are detected, the photographing lens is controlled to the wide angle side, so that the subject can be easily captured within the photographing field angle.

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

  FIG. 1 shows a schematic block diagram of a video camera which is an embodiment of an imaging apparatus according to the present invention.

  The photographing lens 12 of the video camera 10 has an optical zoom function, and forms an optical image of the subject on the imaging surface of the imaging unit 14. For example, the taking lens 12 has a 10 × zoom function with a focal length of 6 mm to 60 mm. A lens driving motor 16 drives the zoom lens of the photographing lens 12 in the optical axis direction.

  The imaging unit 14 converts an optical image from the photographing lens 12 into an image signal. The video signal processing unit 18 performs A / D conversion on the image signal from the imaging unit 14, performs well-known image processing (gamma correction, color balance adjustment, color conversion, etc.) in the video camera, and video data in a predetermined video signal format. Is output. The frame memory 20 temporarily stores video data having a predetermined video frame rate from the video signal processing unit 18. Video data stored in the frame memory 20 is read out, supplied to the display unit 22, and displayed as an image. The photographer can check an image being shot (recorded) from the display image on the display unit 22. That is, the display unit 22 functions as a so-called finder.

  The microphone 24 captures surrounding sounds. The audio signal processing unit 26 A / D-converts the analog audio signal from the microphone 24, compresses and encodes the analog audio signal using the PCM encoding method, and stores the PCM audio data in the PCM buffer 28.

  The DV codec 30 compresses the video data of the video frame stored in the frame memory 20 and the PCM audio data stored in the PCM buffer 28 by a moving image compression encoding method such as Motionn JPEG or MPEG2. The compressed video / audio data is recorded on the DV tape 34 by the tape interface 32.

  The tape interface 32 also reproduces the compressed video / audio data from the DV tape 34 during reproduction, and supplies the reproduction data to the DV codec 30. The DV codec 30 decompresses the compressed video data of the playback data and sequentially stores the playback video data in the frame memory 20. The DV codec 30 also decompresses the compressed audio data and stores the reproduced audio data in the PCM buffer 28. The reproduced video data stored in the frame memory 20 is read at the video frame rate and supplied to the display unit 22 (for example, a liquid crystal display panel). Thereby, the reproduced video is displayed on the screen of the display unit 22. The reproduced audio data stored in the PCM buffer 28 is converted into an analog signal and applied to a speaker (not shown). As a result, reproduced sound is output.

  The photographer or user can input various instructions to the video camera 10 through the operation unit 36 and can operate the video camera 10. A setting menu for the video camera 10, a recording time, a remaining battery level, and the like are displayed on the display unit 22. A CPU (Central Processing Unit) 38 controls each unit according to the operation and operation state of the operation unit 36. The CPU 38 is a so-called system control device.

  The acceleration sensor 40 as the acceleration detecting means is fixed to the video camera 10 so as to detect an acceleration in a direction parallel to the imaging surface of the imaging unit 14, that is, an orthogonal projection component on the imaging surface. Of course, the acceleration sensor 40 may detect acceleration of three or more axes.

With reference to FIG. 2, processing during moving image shooting will be described. If during recording (S1), C PU38 acquires the acceleration α from the detected output of the acceleration sensor 40 (S2), by using the acceleration data acquired in the past, the movement of the digital video camera 10 in the past fixed time period The amount d is calculated (S3). When the current acceleration α exceeds the acceleration threshold α _th (f _prev ) (S4) and the movement amount d exceeds the movement amount threshold d _th (f _prev ) (S5), the CPU 38 is caused by an external impact. Judge that blurring has occurred. The processing of steps S3 and S4 by the CPU 38 corresponds to the subject movement detection means in the claims.

The acceleration threshold value α _th (f _prev ) and the movement amount threshold value d _th (f _prev ) are set to be smaller as the focal length f _prev of the photographing lens 12 is closer to the telephoto side. This corresponds to the fact that the image displayed on the display unit 2 is greatly blurred with respect to the movement of the video camera toward the telephoto side. FIG. 3 shows a change example of the acceleration threshold value α _th (f _prev ) with respect to the focal distance f _prev . FIG. 4 shows an example of change in the movement amount threshold value d _th (f _prev ) with respect to the focal length f _prev . The acceleration threshold value α _th and the movement amount threshold value d _th depend on the focal length f _prev .

If it is determined that the shake has occurred due to the external impact, the CPU 38 calculates the lens driving amount Δf from the focal length f _prev and the moving amount d according to a certain relational expression (S6). FIG. 5 shows an example of the relationship between the focal length f _prev and the moving amount d and the lens driving amount Δf. The horizontal axis represents the focal length f _prev and the vertical axis represents the lens driving amount Δf. The case where d1, d2, and dth are shown as the movement amount d is shown. d1>d2> dth. The larger the movement amount d is, and the larger the current focal length (focal length before control) f _prev is, the larger the lens driving amount Δf is set. That is, the lens driving amount Δf depends on the focal length f _prev and the moving amount d before the control.

  The CPU 38 obtains a direction in which the user should pan in order to capture the subject in the finder, and displays an arrow indicating the direction on the display unit 22 (S7). The panning direction is a direction for canceling the movement amount d, and the panning amount is an amount for canceling the movement amount d. The CPU 38 also drives the focal length of the taking lens 12 to the wide angle side by the change amount Δf (S8). The processing of steps S6, S7, and S8 by the CPU 38 corresponds to the control means in the claims. FIG. 6 is a schematic view of the shooting angle of view and the arrow displayed on the display unit 22 after the shooting lens 12 is driven.

  As described above, by controlling the focal length of the photographing lens 12 to the wide-angle side and instructing the photographer to change the photographing direction, the photographer can quickly pick up a subject that is out of the photographing field angle due to camera shake or external vibration. Can be kept within the shooting angle of view.

  Although the DV tape 34 is exemplified as the recording medium, it is obvious that the recording medium may be an optical disk such as a DVD-R, a magnetic disk such as a hard disk, a nonvolatile semiconductor memory such as a flash memory, or the like.

It is a schematic block diagram of one Example of this invention. It is an operation | movement flowchart of a present Example. It is a figure which shows the relationship between an acceleration threshold value and a focal distance. It is a figure which shows the relationship between a movement amount threshold value and a focal distance. It is a figure which shows the example of a change of the focal distance variation | change_quantity with respect to a focal distance and the movement amount. It is a figure which shows the example of a display of the arrow which shows the change of the imaging | photography field angle before and behind control by a present Example, and a panning direction. FIG. 6 is a diagram illustrating a state in which a subject deviates from a shooting angle of view due to camera shake or external impact in a conventional example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Video camera 12 Shooting lens 14 Image pick-up part 16 Lens drive motor 18 Video signal processing part 20 Frame memory 22 Display part 24 Microphone 26 Audio signal processing part 28 PCM buffer 30 DV codec 32 Tape interface 34 DV tape 36 Operation part 38 CPU (center) Arithmetic processing unit)
40 Acceleration sensor

Claims (4)

An imaging lens having a's over non-functional,
An imaging device having imaging means for converting an optical image of a subject by the photographing lens into an image signal,
Acceleration detecting means for detecting acceleration of the imaging device;
Based on the output of the acceleration detecting means, when the blur in the photographed image is determined to have occurred by the imaging unit, it has a control means for changing the photographing lens to the wide angle side,
The imaging apparatus according to claim 1, wherein the control means increases the amount of change for changing the photographic lens to the wide-angle side as the focal length of the photographic lens increases . An imaging lens having a's over non-functional,
An imaging device having imaging means for converting an optical image of a subject by the photographing lens into an image signal,
Acceleration detecting means for detecting acceleration of the imaging device;
When the movement amount of the imaging device is calculated from the output of the acceleration detection unit , the acceleration detected by the acceleration detection unit exceeds the acceleration threshold value, and the calculated movement amount exceeds the movement amount threshold value , have a control means for changing the photographing lens to the wide angle side,
The imaging apparatus according to claim 1, wherein the control means increases the amount of change for changing the photographic lens to the wide-angle side as the focal length of the photographic lens increases . The imaging apparatus according to claim 2, wherein the control unit increases a change amount for changing the photographing lens to the wide-angle side as the calculated movement amount is larger. 4. The imaging apparatus according to claim 2 , wherein both the threshold value for acceleration and the threshold value for movement amount are set to be smaller as the focal length of the photographing lens is closer to the telephoto side.

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