JP2017005291A - Imaging device, control method thereof, and control program - Google Patents

Abstract

Power consumption is suppressed, and a shutter time lag due to frame rate switching is shortened. A camera system control unit 101 drives and controls an image sensor 102 to selectively switch a frame rate between a first frame rate and a second frame rate faster than the first frame rate. The camera system control unit switches the frame rate from the first frame rate to the second frame rate when performing AF processing in accordance with the image. Photometry is performed according to the image obtained at the frame rate. [Selection] Figure 1

Description

  The present invention relates to an imaging apparatus, a control method thereof, and a control program, and more particularly to an imaging apparatus that performs imaging surface AF processing at a high frame rate.

  In general, in an imaging apparatus that uses an imaging surface AF as an autofocus (AF), a release time lag (also referred to as a sitter time lag) at the time of shooting is long due to the imaging surface AF process. The shutter time lag is after detecting the first shutter switch signal by half-pressing the shutter button to perform AF processing, and after detecting the second shutter switch signal by fully pressing the shutter button until releasing. Of time.

  In order to shorten such a shutter time lag, for example, there is an imaging apparatus in which the frame rate is set to a high speed during AF processing (see Patent Document 1). In Patent Document 1, during AF processing, the amount of information transmitted and received between the lens unit and the imaging apparatus main body is thinned out to maintain a high frame rate during AF processing.

  Furthermore, there is an imaging apparatus that reduces the processing load by increasing the frame rate during AF processing and outputting a thinned image to an electronic viewfinder (EVF) (see Patent Document 2). . In Patent Document 2, the frame rate is changed according to the brightness of the subject immediately before and during the AF process.

JP 2013-25107 A Japanese Patent No. 4558830

  As described above, in Patent Documents 1 and 2, the shutter time lag is shortened by using a frame rate higher than the normal frame rate during AF processing.

  By the way, when the frame rate is increased, the power consumption of the imaging apparatus increases as compared with the normal frame rate. For this reason, it is necessary to switch the frame rate to a normal frame rate after AF processing. If the frame rate is switched during the period from focusing to shooting, the shutter time lag becomes longer by the time required for switching the frame rate.

  Accordingly, an object of the present invention is to provide an imaging apparatus that suppresses power consumption and does not increase the shutter time lag by switching the frame rate, a control method thereof, and a control program.

  In order to achieve the above object, an imaging apparatus according to the present invention is an imaging apparatus including an imaging element that outputs an image corresponding to an optical image, and controls the driving of the imaging element to set a frame rate to a first frame rate. Switching means for selectively switching to a second frame rate faster than the first frame rate, and controlling the switching means when performing AF processing according to the image, the frame rate is set to the second frame rate. Switch from the first frame rate to the second frame rate, and if there is a shooting instruction after the AF process is brought into focus, photometry is performed according to the image obtained at the second frame rate. And a control means to execute.

  The control method according to the present invention is a control method for an image pickup apparatus including an image pickup device that outputs an image according to an optical image, and controls the drive of the image pickup device to change a frame rate between the first frame rate and the first frame rate. A switching step of selectively switching to a second frame rate that is faster than a frame rate, and the switching step when performing AF processing according to the image, the frame rate is changed from the first frame rate to the second frame rate. And a control step of performing photometry by performing photometry according to an image obtained at the second frame rate when a shooting instruction is issued after the AF process is in focus and the in-focus state is achieved. It is characterized by that.

  The control program according to the present invention is a control program used in an imaging apparatus including an imaging element that outputs an image corresponding to an optical image, and controls the drive of the imaging element to a computer included in the imaging apparatus to set a frame rate. A switching step of selectively switching between a first frame rate and a second frame rate faster than the first frame rate, and the switching step when performing AF processing according to the image, the frame rate is changed by the switching step. Switch from the first frame rate to the second frame rate, and if a shooting instruction is given after the AF process is in focus, photometry is performed according to the image obtained at the second frame rate. And a control step for performing photographing.

  According to the present invention, when a shooting instruction is given after the in-focus state is achieved by AF processing, photometry is performed according to an image obtained at a high-speed second frame rate, and shooting is performed. Accordingly, the release time lag can be shortened while suppressing power consumption.

1 is a block diagram illustrating a configuration of an example of an imaging apparatus according to a first embodiment of the present invention. 3 is a flowchart for explaining frame rate switching processing performed by the camera shown in FIG. 1. It is a flowchart for demonstrating the frame rate switching process performed with the camera by the 2nd Embodiment of this invention.

  Hereinafter, an example of an imaging apparatus according to an embodiment of the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 is a block diagram showing the configuration of an example of an imaging apparatus according to the first embodiment of the present invention.

  The illustrated imaging device is, for example, a digital camera (hereinafter simply referred to as a camera), and includes a photographing lens unit (hereinafter simply referred to as a lens unit) 200 and a camera body (imaging device body) 100.

  The camera body 100 includes an image sensor 102 such as a CCD or CMOS sensor, and a shutter 109 is disposed on the front side of the image sensor 102. An optical image (subject image) incident through the lens unit 200 and the shutter 109 is formed on the image sensor 102. The image sensor 102 outputs an electrical signal (analog signal) corresponding to the optical image.

  The A / D converter 103 converts an analog signal that is an output of the image sensor 102 into a digital signal by A / D conversion. The image processing unit 103 performs predetermined image interpolation, resizing processing such as reduction, and color conversion processing on the digital signal output from the A / D converter 103. Note that the image processing unit 103 also performs predetermined image interpolation, resizing processing, and color conversion processing on the image data sent from the memory control unit 105.

  A digital signal that is an output of the A / D converter 103 is written as image data in the memory 109 via the image processing unit 104 and the memory control unit 105 or via the memory control unit 105. The memory 110 stores image data and display image data to be displayed on the display unit 111. This display image data is converted into an analog image signal by the D / A converter 112 and displayed on the display unit 111 as an image.

  By displaying sequentially transferred images on the display unit 111, the display unit 111 can be used as an EVF (electronic viewfinder). As a result, the user can perform live view shooting.

  The nonvolatile memory 113 is an electrically erasable / recordable memory, and for example, an EEPROM is used. The nonvolatile memory 113 stores constants and programs for operation of the camera system control unit 101. And the camera system control part 101 performs the process which concerns on the below-mentioned flowchart by running the program memorize | stored in the non-volatile memory 113. FIG.

  The system memory 114 is, for example, a RAM. In the system memory 115, constants and variables for operation of the camera system control unit 101, a program read from the nonvolatile memory 113, and the like are expanded.

  The system timer 115 is a timer unit that measures the time used for various controls and the time of a built-in clock. The timing generator (TG) 116 sends a timing signal to the image sensor 102, the A / D converter 103, the memory control unit 105, and the D / A converter 112 under the control of the camera system control unit 101. Thereby, the readout timing of the image sensor 102 and the A / D conversion timing by the A / D converter 103 are synchronized. Further, the reading of display image data by the memory control unit 105 and the timing of D / A conversion by the D / A converter 112 are synchronized.

  The operation speed of the image sensor 102 is variable, and the camera system control unit 101 controls the TG 116 to selectively switch the operation speed of the image sensor 102, that is, the frame rate to 30 fps, 60 fps, 120 fps, or the like.

  When the shutter button 117 is pressed halfway (shooting preparation instruction), the first shutter switch (SW1) is turned on, and the first shutter switch signal SW1 is sent to the camera system control unit 101. In response to the first shutter switch signal SW1, the camera system control unit 101 starts operations such as AF (autofocus) processing and AE (automatic exposure) processing.

  When the shutter button 117 is fully pressed (shooting preparation instruction), the second shutter switch (SW2) is turned on, and the second shutter switch signal SW2 is sent to the camera system control unit 101. In response to the second shutter switch signal SW2, the camera system control unit 101 starts a series of shooting processes from reading a signal from the image sensor 102 to writing image data on the recording medium 300.

  The user can use the operation unit 119 to make various settings related to camera shooting such as switching between single shooting mode / continuous shooting mode. The recording medium 300 is a recording medium such as a memory card, and is composed of, for example, a semiconductor memory or a magnetic disk.

  The camera system control unit 101 controls the entire camera. In addition, the camera system control unit 101 performs AF (autofocus) processing by the distance measurement unit 106 and performs AE (automatic exposure) processing by the photometry unit 107 in accordance with the image data output from the image processing unit 104. .

  The AE (automatic exposure) process performed by the photometry unit 107 has a plurality of photometry modes. For example, in the evaluation metering mode, the entire image is metered on average. In the partial metering mode, metering is performed with a weight applied to the metering area set at the center of the image. In the spot photometry mode, photometry is performed with a greater weight on a photometry area that is narrower than that in the partial photometry mode.

  Further, the camera system control unit 101 uses the flicker detection unit 108 to detect 50 Hz / 60 Hz flicker using the image data output from the image processing unit 104. The shutter control unit 110 drives and controls the shutter 109 under the control of the camera system control unit 101.

  The camera body 100 and the lens unit 200 are connected via a lens mount (not shown) as an interface. The lens unit 200 includes a lens system control unit 201. The lens system control unit 201 communicates with the camera system control unit 101 via a lens mount to control the entire lens unit 200.

  The lens unit 200 includes a lens group 202 having a plurality of lenses and a diaphragm 203. The lens driving unit 204 drives a focus positioning lens (for example, a focus lens) along the optical axis under the control of the lens system control unit 201. For example, the lens drive amount is sent from the camera system control unit 101 to the lens system control unit 201, and the lens system control unit 201 controls the lens drive unit 204 according to the lens drive amount to move the lens to the in-focus position. Set to the in-focus state.

  The aperture driving unit 205 controls the aperture 203 under the control of the lens system control unit 201 to drive the aperture in the open direction or the small aperture direction. For example, the aperture drive amount is sent from the camera system control unit 101 to the lens system control unit 201, and the lens system control unit 201 controls the aperture drive unit 205 according to the aperture drive amount to drive the aperture 203.

  FIG. 2 is a flowchart for explaining frame rate switching processing performed by the camera shown in FIG. Note that the processing according to the illustrated flowchart is performed by the camera system control unit 101 developing a program stored in the non-volatile memory 113 in the system memory 114 and executing the program.

  When the camera is turned on, the camera system control unit 101 activates the live view mode and sets the frame rate to the normal operation frame rate (first frame rate, for example, 30 fps) (step S201). Then, the camera system control unit 101 performs photometry as described above (step S202). Thereafter, the camera system control unit 101 determines whether or not the shutter button 117 is half-pressed (half-pressed state) and the first shutter switch (SW1) is turned on (step S203). If SW1 is off (NO in step S203), the camera system control unit 101 returns to the process of step S202 and continues photometry.

  On the other hand, when SW1 is turned on (YES in step S203), the camera system control unit 101 changes the frame rate from the normal operation frame rate (first frame rate) to the high-speed frame rate (second frame rate, for example, 120 fps). (Step S204). Then, the camera system control unit 101 performs AF processing (ranging) (step S205). Here, for example, an imaging surface AF process is performed as the AF process.

  Subsequently, the camera system control unit 101 determines whether or not the peak position has been detected (step S206). That is, the camera system control unit 101 determines whether the in-focus position has been confirmed. If the in-focus position is not confirmed (NO in step S206), the camera system control unit 101 returns to the process of step S205 and continues the AF process.

  On the other hand, when the in-focus position is confirmed (YES in step S206), the camera system control unit 101 drives the lens to the in-focus position by the lens system control unit 201 as described above (step S207).

  Subsequently, the camera system control unit 101 determines whether or not the flicker is detected by the flicker detection unit 108 (step S208). If flicker is not detected (NO in step S208), the camera system control unit 101 determines whether or not the spot photometry mode is set as the photometry mode (step S209).

  If the spot photometry mode is not set (NO in step S209), the camera system control unit 101 determines whether or not the luminance of the subject obtained as a result of photometry is lower than a preset luminance threshold value. (Step S210). If the luminance of the subject is not low (NO in step S210), the camera system control unit 101 determines whether or not the second shutter switch (SW2) is turned on (step S211).

  When SW2 is turned on (YES in step S211), that is, when there is a shooting instruction, the camera system control unit 101 performs light measurement once at the focus range-finding point set in the image at a high frame rate (step S1). S212). When photometry is completed, the camera system control unit 101 captures a still image (step S213). Thereafter, the camera system control unit 101 ends the frame rate switching process.

  When SW2 is off (NO in step S211), the camera system control unit 101 switches the frame rate from the high frame rate to the normal operation frame rate (step S214). Next, the camera system control unit 101 performs photometry at the focus ranging point set in the image at the frame rate during normal operation (step S215). Then, the camera system control unit 101 determines whether SW2 is turned on (step S216).

  If SW2 is off (NO in step S216), camera system control unit 101 returns to the process in step S215 and continues photometry. On the other hand, when SW2 is turned on (YES in step S216), camera system control unit 101 proceeds to the process of step S213.

  If flicker is detected (YES in step S208), the camera system control unit 101 proceeds to the process of step S214, and switches the frame rate from the high frame rate to the normal operation frame rate. Similarly, when the spot photometry mode is set (YES in step S209), the camera system control unit 101 proceeds to the process of step S214. If the luminance of the subject is low (YES in step S210), the camera system control unit 101 proceeds to the process of step S214.

  By the way, when the frame rate is switched, that is, when the frame rate is changed, the usable shutter speed changes. As a result, the number of pixels read from the image sensor 102 in one frame changes. The above-described flicker detection determination and subject luminance determination are related to changes in usable shutter speed.

  When flicker is detected, the effect of flicker is reduced by limiting the shutter speed used for shooting according to the flicker frequency. In this case, since the shutter speed to be used may be one frame (8.3 msec) or more at a high frame rate (120 fps), the frame rate is switched from the high frame rate to the normal operation frame rate. The same applies to the case where the subject brightness after focusing is low.

  The determination of the photometric mode is related to the number of pixels that can be read in one frame. In a photometry mode in which a large weight is applied to a specific photometry area like spot photometry, accurate photometry can be performed when the number of pixels existing in the photometry area is large. Therefore, if the frame rate is switched from the high frame rate to the normal operation frame rate, the number of samples used for photometry can be increased and accurate photometry can be performed.

  In FIG. 2, the normal operation frame rate is set to 30 fps and the high speed frame rate is set to 120 fps. However, the frame rate is not limited to these, and the normal operation frame rate may be less than the high speed frame rate.

  Furthermore, in the above example, it is determined whether or not the metering mode is the spot metering mode. However, the metering area is not limited to the spot metering mode, and the metering area is limited to a specific metering area and weighting is performed. Any mode is acceptable. That is, any photometric mode in which the size of the photometric area is not more than a predetermined size may be used.

  As described above, in the first embodiment of the present invention, when the first and second shutter switches SW1 and SW2 are on at the time of focusing, for example, when the shutter button is pressed at the time of shooting. In addition, the frame rate changing process is not performed before shooting. Thereby, the release time lag can be shortened.

  Further, when the second shutter switch SW2 is not turned on before focusing, the frame rate is changed to the normal operation frame rate immediately after focusing. Thereby, power consumption can be suppressed.

[Second Embodiment]
Next, an example of a camera according to the second embodiment of the present invention will be described. The configuration of the camera according to the second embodiment is the same as that of the camera shown in FIG.

  FIG. 3 is a flowchart for explaining frame rate switching processing performed by the camera according to the second embodiment of the present invention.

  Note that the processing according to the illustrated flowchart is performed by the camera system control unit 101 developing a program stored in the non-volatile memory 113 in the system memory 114 and executing the program. In the illustrated flowchart, the same steps as those in the flowchart shown in FIG. 2 are denoted by the same reference numerals, and the description thereof is omitted.

  In step S210, if the subject is not low brightness, the camera system control unit 101 determines whether or not a predetermined time has elapsed since the lens was driven to the in-focus position (step S311). If the predetermined time has not elapsed (NO in step S311), the camera system control unit 101 performs photometry once at the focus range-finding point set in the image at the high-speed frame rate (step S312). When photometry is completed, the camera system control unit 101 determines whether or not SW2 is turned on (step S313).

  If SW2 is off (NO in step S313), the camera system control unit 101 returns to the process of step S311 and determines whether or not a predetermined time has elapsed. On the other hand, when SW2 is turned on (YES in step S313), the camera system control unit 101 captures a still image (step S314). Thereafter, the camera system control unit 101 ends the frame rate switching process.

  When the predetermined time has elapsed (YES in step S311), the camera system control unit 101 switches the frame rate from the high-speed frame rate to the normal operation frame rate (step S315). Thereafter, the camera system control unit 101 proceeds to the process of step S312, and performs photometry once at the focus ranging point set in the image at the frame rate during normal operation.

  When flicker is detected, when the spot photometry mode is set, or when the luminance of the subject is low, the camera system control unit 101 proceeds to the process of step S315.

  Thus, in the second embodiment of the present invention, the time-out period is provided when determining whether or not the second shutter switch SW2 is turned on. Also in the second embodiment, similarly to the first embodiment, the release time lag can be shortened, and the power consumption can be suppressed.

  As is clear from the above description, in the example shown in FIG. 1, the camera system control unit 101 and the TG 116 function as a switching unit, and the camera system control unit 101 and the photometry unit 106 function as a control unit.

  As mentioned above, although this invention was demonstrated based on embodiment, this invention is not limited to these embodiment, Various forms of the range which does not deviate from the summary of this invention are also contained in this invention. .

  Moreover, what is necessary is just to make an imaging device perform this control method by using the function of said embodiment as a control method. Further, a program having the functions of the above-described embodiments may be used as a control program, and the control program may be executed by a computer included in the imaging apparatus. The control program is recorded on a computer-readable recording medium, for example.

[Other Embodiments]
The present invention supplies a program that realizes one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and one or more processors in a computer of the system or apparatus read and execute the program This process can be realized. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

100 Imaging device body (camera body)
DESCRIPTION OF SYMBOLS 101 Camera system control part 102 Image pick-up element 104 Image processing part 106 Distance measurement part 107 Photometry part 108 Flicker detection part 200 Lens unit 201 Lens system control part 204 Lens drive part

Claims (11)

An imaging device including an imaging device that outputs an image according to an optical image,
Switching means for driving and controlling the image sensor to selectively switch the frame rate between a first frame rate and a second frame rate faster than the first frame rate;
When the AF process is performed in accordance with the image, the switching unit is controlled to switch the frame rate from the first frame rate to the second frame rate. Control means for performing photometry by performing photometry according to an image obtained at the second frame rate when instructed;
An imaging device comprising:   2. The imaging apparatus according to claim 1, wherein the control unit starts the AF process when the shutter button is in a half-pressed state, and the imaging instruction is given when the shutter button is fully pressed. . Equipped with flicker detection means to detect flicker during shooting,
When the flicker is detected by the flicker detection unit, the control unit controls the switching unit to switch the frame rate from the second frame rate to the first frame rate, and then The imaging apparatus according to claim 1, wherein the imaging is performed by performing photometry according to an image obtained at the frame rate.   When the predetermined photometry mode is set, the control unit controls the switching unit to switch the frame rate from the second frame rate to the first frame rate. 4. The imaging apparatus according to claim 1, wherein the imaging is performed by performing photometry according to an image obtained at a frame rate of 4.   The imaging apparatus according to claim 4, wherein the predetermined photometry mode is a photometry mode in which a size of a photometry area set in the image is equal to or smaller than a predetermined size.   The control means controls the switching means to set the frame rate when the luminance obtained as a result of performing photometry according to the image obtained at the second frame rate is equal to or lower than a predetermined luminance threshold value. 6. The method according to claim 1, wherein after switching from the second frame rate to the first frame rate, photometry is performed in accordance with an image obtained at the first frame rate to perform shooting. The imaging device according to any one of the above.   The control means controls the switching means to switch the frame rate from the second frame rate to the first frame rate when there is no shooting instruction after the in-focus state, The imaging apparatus according to claim 1, wherein photometry is performed according to an image obtained at a first frame rate, and imaging is performed when the imaging instruction is issued.   The control means determines whether or not a predetermined time has elapsed since the AF process has been brought into focus. If the predetermined time has not elapsed, an image obtained at the second frame rate is obtained. The imaging apparatus according to claim 1, wherein after performing photometry in response to the measurement, the imaging is performed when the imaging instruction is issued.   When the predetermined time has elapsed, the control unit controls the switching unit to switch the frame rate from the second frame rate to the first frame rate, and then obtains the frame rate at the first frame rate. 9. The imaging apparatus according to claim 8, wherein photometry is performed in accordance with the received image, and imaging is performed when the imaging instruction is issued. A method for controlling an imaging apparatus including an imaging device that outputs an image according to an optical image,
A switching step of driving and controlling the image sensor to selectively switch the frame rate between a first frame rate and a second frame rate faster than the first frame rate;
When performing AF processing according to the image, the switching step switches the frame rate from the first frame rate to the second frame rate, and there is a shooting instruction after the AF processing is in focus. And a control step for performing photometry according to the image obtained at the second frame rate and performing shooting,
A control method characterized by comprising: A control program used in an imaging device including an imaging device that outputs an image according to an optical image,
In the computer provided in the imaging device,
A switching step of driving and controlling the image sensor to selectively switch the frame rate between a first frame rate and a second frame rate faster than the first frame rate;
When performing AF processing according to the image, the switching step switches the frame rate from the first frame rate to the second frame rate, and there is a shooting instruction after the AF processing is in focus. And a control step for performing photometry according to the image obtained at the second frame rate and performing shooting,
A control program characterized by causing

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