JP2010171848A - Imaging device, and control method and control program of imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging device that increases the number of photographable pictures. <P>SOLUTION: The image device includes a movement determining means 111 of determining whether a subject is a moving body and a battery voltage detecting means 123 of detecting a battery voltage, and applies global shutter driving to an imaging element to photograph a still picture using a mechanical shutter when the voltage value detected by the battery voltage detecting means 123 is higher than a predetermined level and the determination means 111 determines that the subject is a moving body or applies rolling shutter driving to the imaging element to photograph a still picture when the voltage value detected by the battery voltage detecting means 123 is less than or equal to a predetermined level or when the movement determination means 111 determines that the subject is not a moving body. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an imaging apparatus, an imaging apparatus control method, and a control program.

  Conventionally, a CCD (Charge Coupled Device) has been mainly used as an image sensor of a digital still camera (hereinafter also referred to as a digital camera). However, in recent years, low power consumption and a simple manufacturing process are used. The number of models using CMOS (Complementary Metal Oxide Semiconductor) sensors is increasing due to advantages such as high-speed and high-speed signal readout.

  However, some unique problems that arise from using CMOS sensors are also known. One of the typical problems is called “rolling shutter problem”, “simultaneous accumulation”, etc. Specifically, “moving object distortion” that occurs when shooting a moving subject quickly, This is a phenomenon called “in-plane flicker” or the like that is observed under alternating-lighting illumination.

  With a CCD, pixel data used for imaging is read out simultaneously, and all pixels are simultaneously started by an electronic shutter, so such a problem does not occur. However, with a CMOS sensor, an electronic shutter and pixel data reading operation are performed in a pixel. The above-mentioned problems occur because the lines are sequentially shifted for each line.

  In order to deal with this problem, some CMOS sensors have a function of collectively resetting all rows and all pixels, like a CCD. However, since reading of pixel data is performed for each row (scanning line), it is necessary to use a mechanical shutter together to prevent an exposure difference for each row.

  As described above, the CMOS sensor has a driving mode for starting exposure and reading pixel data for each row (hereinafter referred to as rolling shutter driving) and a driving mode for starting exposure for all pixels at once (hereinafter referred to as global shutter driving). In general, it has become common to use rolling shutter drive for moving image shooting and global shutter drive for still image shooting.

  Japanese Patent Laid-Open No. 2004-268831 switches the image sensor driving method according to the imaging mode and subject conditions, and when the image sensor driving method is switched, the image sensor is initialized to quickly move to the next imaging state. An imaging apparatus to be transferred is disclosed. Further, in Patent Document 2, when flicker is detected by the flicker detection unit, flicker is generated by changing the photoelectric conversion characteristic of the image sensor to a photoelectric conversion characteristic in which the linear characteristic region is dominant. However, an imaging apparatus that removes the influence and performs imaging is disclosed.

  Further, in Patent Document 3, when the voltage of the battery is detected and this voltage value is higher than the end voltage value and smaller than the pre-end voltage value, the electronic shutter is not driven without driving the mechanical shutter during imaging. A digital camera that controls and captures an image is disclosed. Patent Document 4 discloses a first exposure control in which exposure is started by simultaneous reset of all rows of the image sensor and exposure is ended by closing the mechanical shutter, and exposure is started by reset in units of rows of the image sensor, and pixel signals The second exposure control for ending exposure by reading is performed, and one still image recording in the first exposure control and a plurality of still image recording in the second exposure control are continuously performed. An imaging apparatus is disclosed.

  However, in the technique described in Patent Document 1, since it is determined whether or not the mechanical shutter is used together depending only on the subject condition regardless of the battery voltage, it is desired to shoot even if some distortion occurs at the end of the battery. There is a problem that it is not possible to respond when there is. In addition, the technique described in Patent Document 2 has a problem of increasing the cost of the device because a special sensor having a logarithmic conversion circuit added in the pixel must be used.

  Furthermore, the technology described in Patent Document 3 does not use a mechanical shutter between the pre-end level and the end level, and the power consumption suppression effect cannot be obtained until the battery reaches the pre-end level. There is. In addition, the technique described in Patent Document 4 does not determine whether or not the subject is subject to moving body distortion, which leads to useless shooting with the mechanical shutter driven, and the number of shots cannot be increased. There's a problem.

  As described above, when the global shutter drive mode is used at the time of still image shooting, it is essential to use a mechanical shutter together. Here, in order to drive the mechanical shutter, a current of several hundred mA is generally required, and this current value needs to be increased as the shutter speed is increased.

  In a portable device such as a digital still camera using a battery, the current of several hundred mA is a very large ratio with respect to the amount of current consumed by the entire device. In particular, when the battery voltage is lowered, the mechanical Whether or not shooting is possible depends on whether or not the shutter is driven, and since the mechanical shutter must be driven, a photo opportunity may be missed. In addition, although a CMOS sensor with low power consumption is used, there may be a problem that the number of shootable images cannot be increased as compared with a model using a conventional CCD sensor.

  In view of this, the present invention provides a battery for an image pickup apparatus by taking a picture while selecting whether the drive mode of the image pickup element is a global shutter drive or a rolling shutter drive based on a subject condition and a battery voltage condition. It is an object of the present invention to provide an imaging apparatus, an imaging apparatus control method, and a control program that can reduce the consumption of the imaging apparatus and can significantly increase the number of images that can be captured.

  In order to achieve such an object, an imaging apparatus according to claim 1 includes an imaging optical system including a mechanical shutter, and an imaging element that can be driven by two driving methods of global shutter driving and rolling shutter driving. The image pickup apparatus includes a movement determination unit that determines whether or not the subject is a moving object and a battery voltage detection unit that detects a battery voltage, and the voltage value detected by the battery voltage detection unit exceeds a predetermined level, and the movement determination unit If the subject is determined to be a moving object, the image sensor is driven as a global shutter and a still image is shot using a mechanical shutter, and the voltage value detected by the battery voltage detection means is below a predetermined level, or the motion is determined. If it is determined by the means that the subject is not a moving object, the image sensor is used as a rolling shutter drive to take a still image. Than is.

  According to a second aspect of the present invention, there is provided the imaging apparatus according to the first aspect, further comprising flicker determining means for determining whether or not flicker is present in the light source, and the voltage value detected by the battery voltage detecting means. Is less than a predetermined level, or when the subject is not a moving object by the motion determination means, and when the flicker determination means determines that flicker is present in the light source, the image sensor is set to global shutter drive. Still image shooting is performed using a mechanical shutter.

  The invention according to claim 3 is the image pickup apparatus according to claim 1, further comprising shooting mode setting means for setting whether to permit still image shooting with a rolling shutter drive in advance. It is provided.

  According to a fourth aspect of the present invention, there is provided a method for controlling an image pickup apparatus including an imaging optical system including a mechanical shutter and an image pickup element capable of being driven by two drive methods of global shutter drive and rolling shutter drive. A method for controlling an apparatus, wherein a voltage value detected by a battery voltage detection process for detecting a battery voltage exceeds a predetermined level, and a subject is determined to be a moving object by a motion determination process for determining whether the subject is a moving object. If the image sensor is a global shutter drive and a mechanical shutter is used to take a still image, the voltage value detected by the battery voltage detection process is below a predetermined level, or the subject is not a moving object by the motion determination process In this case, still image shooting is performed by using the image pickup element as a rolling shutter drive.

  According to a fifth aspect of the present invention, there is provided a control program for an image pickup apparatus including an image pickup optical system including a mechanical shutter and an image pickup element capable of being driven by two drive methods of global shutter drive and rolling shutter drive. When the voltage value detected by the battery voltage detection process for detecting the battery voltage exceeds a predetermined level and the object is determined to be a moving object by the movement determination process for determining whether the object is a moving object When the element is operated as a global shutter and still image shooting is performed using a mechanical shutter and the voltage value detected by the battery voltage detection process is below a predetermined level, or when the subject is determined not to be a moving object by the motion determination process, Still image shooting is executed with the image sensor as a rolling shutter drive.

  According to the present invention, it is possible to suppress the battery consumption of the imaging apparatus and to greatly increase the number of images that can be shot as compared with the conventional technique.

It is an example of the external view of the imaging device which concerns on this invention, Comprising: (a) is a top view, (b) is a rear view, (c) is a front view. It is an example of a functional block diagram of an imaging device. It is a flowchart which shows an example of the imaging operation of an imaging device. 12 is a flowchart illustrating another example of the imaging operation of the imaging device. 12 is a flowchart illustrating another example of the imaging operation of the imaging device.

  Hereinafter, the configuration according to the present invention will be described in detail based on the embodiment shown in FIGS.

1. Configuration of Imaging Device A digital camera will be described below as an example of an imaging device according to the present invention. FIG. 1 shows an example of an external view of a digital camera. 1A is a top view, FIG. 1B is a rear view, and FIG. 1C is a front view.

  As shown in FIGS. 1A to 1C, a release key (button) 1, a mode switching dial 2, and a power key 3 are disposed on the upper surface of the digital camera body. An LCD monitor (display unit) 4, a cross key 5, and an optical viewfinder (back) 6 are provided on the back of the digital camera body. Further, an optical viewfinder (front surface) 6, a photographing lens 7 and a flash 8 are provided on the front surface of the digital camera body.

  FIG. 2 is a block diagram showing an example of functional blocks of the digital camera. The system configuration inside the digital camera will be described below.

  The optical unit (imaging optical system) 100 includes a lens 101, a diaphragm / shutter 102, an infrared cut filter 103, and a CMOS sensor 104. The lens 101 mechanically changes its position at the time of focusing, zooming, and starting / stopping. The aperture / shutter 102 switches to an appropriate aperture diameter at the time of shooting, or closes / opens the shutter at the time of still image shooting. The operation is performed.

  The optical system driving unit 105 operates the optical unit 100 to drive focus / zoom and shutter.

  The control / arithmetic unit 120 gives a driving instruction to the optical system driving unit 105 and executes the program stored in the program memory 121 and the operation content from the operation unit 122 by the user, thereby controlling each unit of the imaging apparatus. Control. The imaging apparatus control program according to the present invention is stored in, for example, the program memory 121, and the imaging program is read and executed by the control / calculation unit 120, so that the imaging apparatus will be described later. It is to function.

  The battery voltage detection unit 123 in the control / calculation unit 120 always monitors the voltage (battery voltage) of the battery 124 while the imaging apparatus is powered on. In the present embodiment, the monitoring level of the battery voltage by the battery voltage detection unit 123 is performed in two stages, a near end level (hereinafter also referred to as NE level) and an end level (hereinafter also referred to as E level). It is not limited to. When the battery voltage by the battery voltage detection unit 123 reaches the E level, it is determined that the photographing is impossible, and the control / calculation unit 120 performs the power-off process. The DC / DC converter 125 generates various DC voltages from the battery 124 in order to supply power for all units.

  The CMOS sensor (imaging device) 104 can be driven by two driving methods, global shutter driving and rolling shutter driving, and converts an optical image formed by the light receiving element portions arranged in two dimensions into a charge element. The electric signal is output to the outside according to the read timing transmitted from the drive unit. The signal output from the CMOS sensor 104 is subjected to image processing in a predetermined format in the subsequent image processing unit 110 in still image shooting, and the recorded image is an image memory 127 (SD card, Compact Flash (registered trademark) card, XD Saved on a picture card or other media). In the monitoring, the image processing unit 110 processes the image as a display image and updates and displays it on the LCD 4 as needed.

  The SDRAM 128 performs white balance processing, interpolation processing, γ processing, YUV processing, noise reduction processing, contour enhancement processing, compression processing, and the like, which are performed in the process of generating a recording image and a display image in the image processing unit 110. Used as a data buffer for temporary storage.

  The movement determination unit 111 of the image processing unit 110 determines the movement of the subject. Here, as a method for determining whether or not there is a moving subject, for example, in the monitoring state before entering the shooting process, an inter-frame difference is taken, and whether the difference is larger or smaller than a predetermined threshold value. And a method of mounting an AF module and using a function of detecting a moving object as a function of the AF module can be used. At this time, it is also preferable that the user can set a threshold value used for determining whether or not there is movement. Note that the motion determination method of the motion determination unit 111 in the present embodiment is not limited to the above-described example, and other known or new methods can be used.

  Similar to the motion determination unit 111, the flicker determination unit 112 of the image processing unit 110 determines whether or not the luminance level fluctuates within a certain period in the monitoring state before entering the shooting process. is there. At this time, it is also preferable that the user can set a threshold value used for determination of the presence or absence of flicker. Note that the determination method by the flicker determination unit 112 in the present embodiment is not limited to the above example, and other known or new methods can be used.

  The shooting mode selection unit 126 can set whether to allow still image shooting by driving the rolling shutter. For example, the shooting mode selection unit 126 displays a shooting mode selection screen on the LCD 4 and is set by the user through the operation unit 122. The contents are stored. For example, assuming shooting of an athlete race at an athletic meet, if it is before the start during monitoring, the motion determination means 111 may determine that the subject does not move, and if the runner starts running and releases the release, There is a possibility that photographing with the shutter is performed, and an image with moving body distortion is taken. In the present embodiment, in order to prevent this, when the user dislikes shooting with moving body distortion, the shooting mode setting means 126 can be set not to allow shooting with the rolling shutter.

2-1. First Embodiment Hereinafter, an operation of an imaging apparatus (an imaging apparatus control method according to the present invention) will be described.

  FIG. 3 is a flowchart showing an example (first embodiment) of an imaging operation executed by the imaging apparatus according to the present invention.

  First, when the release button 1 is pressed (S11: Yes), it is determined whether the battery voltage V detected by the battery voltage detector 123 is higher than the NE level or lower than the NE level (S12). Of course, when the battery voltage V is NE level or equal, it is possible to appropriately select which process is performed.

  If it is below the NE level (S12: No), the imaging process (S15) is performed by the rolling shutter without driving the mechanical shutter.

  On the other hand, when it is higher than the NE level (S12: Yes), the motion determination unit 111 determines whether or not there is a moving subject within the angle of view (S13).

  When the determination by the movement determination unit 111 determines that there is no moving subject within the angle of view (S13: No), there is no possibility of causing a moving body distortion, and therefore shooting by rolling shutter driving without driving the mechanical shutter is performed. Is done.

  On the other hand, if it is determined that there is a moving subject within the angle of view (S13: Yes), the image sensor is switched to global shutter drive in order to prevent the moving image from being distorted in the captured image, and the mechanical shutter. And taking a picture (S14).

  Image data photographed by the global shutter driving and mechanical shutter imaging processing (S14) and rolling shutter imaging processing (S15) methods are sent from the image sensor to the image processing unit 110, and an imaging processing block (not shown) White balance processing, interpolation processing, γ processing, YUV processing, noise reduction processing, contour enhancement processing, compression processing, and the like are performed and recorded in the image memory 127.

  In this manner, the motion detection unit 110 and the battery voltage detection unit 123 are provided, and the image sensor drive mode is selected as the global shutter drive or the rolling shutter drive based on the subject condition and the battery voltage condition. By taking a picture, it is possible to suppress the battery consumption of the image pickup apparatus, and it is possible to significantly increase the number of pictures that can be taken without increasing the battery capacity.

2-2. Second Embodiment FIG. 4 is a flowchart showing another example (second embodiment) of an imaging operation executed by the imaging apparatus according to the present invention. Note that the description of the same points as in the first embodiment will be omitted.

  First, when the release button 1 is pressed (S21: Yes), it is determined whether the voltage V detected by the battery voltage detector 123 is higher than the NE level or lower than that level (S22).

  When the level is below the NE level (S22: No), the flicker determination unit 112 determines whether flicker has occurred (S24). If the flicker determination unit 112 determines that there is flicker in the plane (S24: Yes), the image pickup element is switched to global shutter drive in order to prevent recording an image with in-plane flicker. The photographing process using the shutter together (S25) is performed.

  On the other hand, when it is determined that no flicker occurs in the plane (S24: No), the imaging process (S26) is performed by the rolling shutter without driving the mechanical shutter.

  If it is higher than the NE level (S22: Yes), the motion determination unit 111 determines whether there is a moving subject within the angle of view (S23).

  When the determination by the motion determination unit 111 determines that there is no moving subject within the angle of view (S23: No), the flicker determination unit 112 determines whether flicker has occurred (S24).

  On the other hand, if it is determined that there is a moving subject within the angle of view (S23: Yes), the image sensor is switched to the global shutter drive to prevent the moving image from being distorted in the captured image, and the mechanical shutter. A photographing process (S25) is performed in combination.

  That is, in the second embodiment, even if the battery voltage is equal to or lower than the NE level or there is no subject moving within the angle of view, if flicker occurs, an image with in-plane flicker is displayed. In order to prevent recording, the image sensor is driven by a global shutter, and photographing using a mechanical shutter is performed.

  In this manner, the flicker determination unit 112 is further provided, and in the case of shooting under a light source that causes uneven luminance in the surface by determining the presence or absence of flicker, the driving mode of the image sensor is set to the global shutter. By performing shooting using a mechanical shutter together with driving, it is possible to automatically capture an image without luminance unevenness.

2-3. Third Embodiment FIG. 5 is a flowchart illustrating another example (third embodiment) of an imaging operation performed by the imaging apparatus according to the present invention. Note that the description of the same points as in the first and second embodiments is omitted.

  First, when the release button 1 is pressed (S31: Yes), it is determined in advance by the shooting mode setting means 126 whether or not the user is set to permit still image shooting with the rolling shutter (S32).

  If the setting by the shooting mode setting means 126 does not permit still image shooting with the rolling shutter (S32: No), the imaging device is switched to global shutter drive, and shooting processing (S36) is performed using the mechanical shutter together. Is called.

  On the other hand, when the setting by the shooting mode setting means 126 permits still image shooting with the rolling shutter (S32: Yes), the process proceeds to S33 and subsequent steps. Note that the processing in S33 to S37 is the same as that in the second embodiment, and a description thereof will be omitted.

  In this manner, the photographing mode setting means 126 is further provided, and it is possible to set in advance whether or not photographing by the rolling shutter is permitted according to the user's intention, so that, for example, a frame is entered during photographing. An image free from moving object distortion can be taken even for a subject.

  The above-described embodiment is a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the gist of the present invention. For example, in the above-described embodiment, an example in which the imaging apparatus is applied to a digital still camera has been described. However, the imaging apparatus according to the present invention can be applied to, for example, a digital video camera, a mobile phone with a camera function, and the like.

1 Release key (button)
2 Mode switching dial 3 Power key 4 LCD monitor 4
5 Cross key 6 Optical viewfinder 7 Shooting lens 8 Flash 100 Optical unit 101 Lens 102 Aperture / shutter 103 Infrared cut filter 104 CMOS sensor 105 Optical system drive unit 110 Image processing unit 111 Motion determination unit 112 Flicker determination unit 120 Control / calculation unit 121 Program Memory 122 Operation Unit 123 Battery Voltage Detection Unit 124 Battery 125 DC / DC Converter 126 Shooting Mode Setting Unit 127 Image Memory 128 SDRAM

JP 2007-19706 A JP 2006-13593 A JP 2005-39417 A JP 2008-306684 A

Claims (5)

In an imaging apparatus including an imaging optical system including a mechanical shutter, and an imaging element that can be driven by two driving methods of global shutter driving and rolling shutter driving,
A movement determination means for determining whether or not the subject is a moving object and a battery voltage detection means for detecting a battery voltage;
When the voltage value detected by the battery voltage detection unit exceeds a predetermined level and the motion determination unit determines that the subject is a moving object, still image shooting is performed using a mechanical shutter with the image sensor as a global shutter drive. Done
When the voltage value detected by the battery voltage detection unit is a predetermined level or less, or when the motion determination unit determines that the subject is not a moving object, still image shooting is performed by driving the image sensor as a rolling shutter. An imaging device. Flicker determination means for determining whether flicker is present in the light source,
When the voltage value detected by the battery voltage detection means is below a predetermined level, or when the subject is determined not to be a moving object by the motion determination means, flicker exists in the light source by the flicker determination means If it is determined,
The image pickup apparatus according to claim 1, wherein still image shooting is performed using a mechanical shutter with the image pickup element as a global shutter drive.   The imaging apparatus according to claim 1, further comprising shooting mode setting means for setting whether to allow still image shooting with a rolling shutter drive in advance. A control method for an imaging apparatus comprising: an imaging optical system including a mechanical shutter; and an imaging element that can be driven by two driving methods of global shutter driving and rolling shutter driving.
If the voltage value detected by the battery voltage detection process for detecting the battery voltage exceeds a predetermined level and the object is determined to be a moving object by the motion determination process for determining whether the object is a moving object, the image sensor is Taking a still image using a mechanical shutter as the shutter drive,
When the voltage value detected by the battery voltage detection process is a predetermined level or less, or when it is determined by the motion determination process that the subject is not a moving object, still image shooting is performed with the image sensor as a rolling shutter drive. Control method for imaging apparatus. An imaging apparatus including an imaging optical system including a mechanical shutter and an imaging element that can be driven by two driving methods of global shutter driving and rolling shutter driving.
If the voltage value detected by the battery voltage detection process for detecting the battery voltage exceeds a predetermined level and the object is determined to be a moving object by the motion determination process for determining whether the object is a moving object, the image sensor is Use a mechanical shutter as a shutter drive to perform still image shooting,
When the voltage value detected by the battery voltage detection process is equal to or lower than a predetermined level, or when it is determined by the motion determination process that the subject is not a moving object, still image shooting is performed by driving the image sensor as a rolling shutter. An imaging device control program.

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