JP2005117395A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging apparatus whereby an image obtained by exposure can be visually recognized during a long exposure time period. <P>SOLUTION: The imaging apparatus reads pixel signals from nearly the entire pixels of an imaging element for a prescribed period during a period of main exposure in a setting state of a long-second monitoring mode, summates the pixel signals at every reading, and displays an image configured by the summated pixel signals on an LCD. When the completion of the main exposure is instructed by full depression of a shutter button 9 again by a photographer or it is discriminated that a proper exposure is obtained on the basis of a pixel value of the summated pixel signals configuring the image, the imaging apparatus uses a newest summated image stored in a second image storage section for a recording image. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an imaging apparatus having a function of displaying an image of a subject during an exposure operation for generating a pixel signal for recording.

  As an imaging device equipped with an imaging device that photoelectrically converts a light image of a subject, a relatively long time (for example, 5 seconds), and a period for performing an exposure operation (hereinafter referred to as a main exposure operation) for obtaining a recording pixel signal In some cases, the pixel signal obtained by the exposure operation of the image sensor is used to generate a pixel signal to be recorded in a recording unit such as a memory card. In this case, since there is no pixel signal that can be used for purposes other than recording, the state of the subject is not displayed as a live view image on the display unit during the main exposure operation. Therefore, the photographer needs to visually recognize the subject and determine a subject image to be captured at a timing when the subject is in a desired state.

On the other hand, Patent Document 1 below discloses a plurality of video signals (images) generated by continuously exposing a CCD a plurality of times during long exposure for the purpose of obtaining a long exposure image with little deterioration in image quality. ) Are added to generate a long-exposure image.
JP 2002-27326 A

  By the way, in view of the need to determine the subject image by directly viewing the subject in the imaging device described above, even if the live view image is displayed on the display unit during the main exposure operation, When an image showing the state of the subject is displayed as a live view image, the displayed live view image is different from the recorded image, so what kind of image does not appear until a series of imaging operations of the imaging device is completed. It is unclear whether it was obtained, and the image recorded in the recording unit may be significantly different from the desired image. Therefore, it is preferable that the state of the recorded image can be viewed in real time during the main exposure operation.

  The cited document 1 has a configuration in which a long-time exposure image is generated by adding a plurality of video signals (images) obtained from a CCD during long-time exposure, but during a long-time exposure period, It does not have a configuration for displaying a long-exposure image formed by adding video signals on the display unit.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an imaging apparatus capable of visually recognizing an image obtained by the exposure during a long exposure period.

  According to the first aspect of the present invention, the image sensor includes a plurality of types of pixels that receive different colors, and an exposure operation for generating a recording pixel signal to be recorded in a predetermined recording unit. An input operation unit for instructing, and an imaging control unit that outputs a pixel signal at a predetermined time interval to substantially all of the plurality of pixels of the image sensor when the exposure start instruction is performed by the input operation unit; An addition processing unit that sequentially adds pixel signals obtained from substantially all the pixels every predetermined time, a recording unit that records pixel signals sequentially generated by the addition processing by the addition processing unit, and the addition processing And an image display unit that updates and displays pixel signals sequentially generated by addition processing by the unit as a display image.

  According to a second aspect of the present invention, in the imaging apparatus according to the first aspect, an exposure state deriving unit for deriving an exposure state of the image sensor based on pixel signals sequentially generated by the addition process, and the display image And an exposure status display control unit that displays the derived exposure status of the image sensor on the image display unit in synchronization with the display process.

The invention according to claim 3 is the imaging device according to claim 1 or 2, wherein an amplification unit that amplifies a pixel value of a pixel signal output from a pixel of the imaging element and outputs the pixel value to the addition processing unit;
A mode switching control unit for switching a mode between a first amplification mode in which an amplification factor of amplification processing by the amplification unit is constant and a second amplification mode in which the amplification factor is changed; When the exposure start instruction is given by the input operation unit, the switching control unit sets the first amplification mode, and the image display unit is configured by the pixel signal amplified at the constant amplification factor. An image is displayed.

  According to a fourth aspect of the present invention, the imaging apparatus according to any one of the first to third aspects further includes an input operation unit for inputting an instruction to cause the image display unit to perform display processing of the display image. It is characterized by.

  According to a fifth aspect of the present invention, in the imaging device according to any one of the first to third aspects, an instruction to start and end an exposure operation by the imaging element for generating the recording pixel signal can be given. A mode setting unit that sets the bulb shooting mode, and an exposure time calculation unit that calculates an exposure time based on the luminance of the subject, and the image display unit is set to the bulb shooting mode by the mode setting unit, Alternatively, the display image display process is performed when the exposure time calculated by the exposure time calculation unit is longer than a predetermined time.

  According to the first aspect of the present invention, when an exposure start instruction is given by the input operation unit, pixel signals are output at a predetermined time interval to substantially all of the plurality of pixels of the image sensor, and the predetermined time interval is set. The pixel signals obtained from almost all the pixels are sequentially added, and the pixel signals sequentially generated by this addition process are recorded and displayed renewably as a display image, so during a long exposure period, An image obtained by the exposure can be visually recognized.

  According to the second aspect of the present invention, the exposure state of the image sensor is derived based on the pixel signals sequentially generated by the addition process, and the derived exposure of the image sensor is synchronized with the display image display process. Since the state is displayed on the image display unit, the photographer can visually recognize the exposure state (exposure state) of the image sensor during the long exposure period.

  According to the third aspect of the present invention, when an exposure start instruction is given by the input operation unit, the first amplification mode in which the amplification factor of the amplification process by the amplification unit is constant is set, and the constant amplification factor is set. Since an image composed of the amplified pixel signals is displayed, an image having a brightness substantially corresponding to the exposure state of the image sensor is displayed on the image display unit. Thereby, the exposure state (exposure state) of the image sensor can be visually recognized by the image displayed on the image display unit.

  According to the fourth aspect of the present invention, since the image display unit is provided with the input operation unit for inputting an instruction to perform the display processing of the display image, when the photographer desires, a long exposure period is provided. The image obtained by the exposure can be confirmed inside.

  According to the fifth aspect of the present invention, when the bulb photographing mode is set by the mode setting unit, or when the exposure time calculated by the exposure time calculation unit is longer than a predetermined time, the display image is displayed. Since processing is performed, an image obtained by long exposure is automatically displayed.

  An embodiment of an imaging apparatus according to the present invention will be described.

  FIG. 1 is a front view of the imaging apparatus 1, and FIG. 2 is a rear view of the imaging apparatus 1.

  As shown in FIGS. 1 and 2, the imaging apparatus 1 includes a power button 2, an optical system 3, an LCD (Liquid Crystal Display) 4, an optical finder 5, a built-in flash 6, a mode setting switch 7, A quadruple switch 8, a shutter button 9, and a long-second monitoring switch 10 are provided.

  The power button 2 is used to switch on / off the power of the imaging apparatus 1.

  The optical system 3 includes a zoom lens, an unillustrated mechanical shutter, and the like, and forms an optical image of a subject on an imaging surface of an imaging element 11 (see FIG. 3) such as a CCD (Charge Coupled Device). is there.

  The LCD 4 displays a live view image and an image (recorded image) recorded on a memory card m (see FIG. 3), which will be described later, and reproduces and displays an image recorded on the memory card m.

  The live view image is an image picked up by the image pickup device 11 that is switched and displayed on the LCD 4 at a constant period (1/30 second) until the image of the subject is recorded. The state is displayed on the LCD 4 in substantially real time, and the photographer can check the state of the subject on the LCD 4.

  The optical viewfinder 5 enables optical observation of a range where a subject is photographed.

  The built-in flash 6 irradiates the subject with illumination light when the amount of exposure to the image sensor 11 is insufficient.

  The mode setting switch 7 is a “shooting mode” for shooting a subject image, a “playback mode” for playing back and displaying a shot image recorded on the memory card m on the LCD 4, and a “menu mode” for setting various functions. "Is a switch for setting the mode switching between the The mode setting switch 7 is composed of a three-contact slide switch that slides up and down. When the switch is set down, the image pickup apparatus 1 is set to the shooting mode. When the switch is set at the center, the playback mode is set. Is done.

  Although not described in detail, the quadruple switch 8 is a switch for performing movement of the zoom lens in the optical axis direction, exposure correction, frame advance of a recorded image to be reproduced on the LCD 4, and the like. Further, the imaging apparatus 1 of the present embodiment includes a program AE mode, an aperture priority AE mode, a shutter speed priority AE mode, and a manual mode as types of shooting modes, and a menu mode is set by the mode setting switch 7. These modes can be switched by operating the quadruple switch 8 in this state.

  The program AE mode is a mode in which a combination of an aperture value and a shutter speed is automatically set according to a preset AE (Auto Exposure) program. The aperture priority AE mode is an aperture value preset by a photographer. The shutter speed setting AE mode is a mode in which an image is taken by setting an aperture value at a shutter speed preset by the photographer, and the manual mode is a mode in which the photographer takes a picture. Is a mode in which imaging is performed with a shutter speed and an aperture value set in advance.

  The shutter button 9 is a button that is pressed in two stages, that is, a fully-pressed operation that is fully pressed and a half-pressed operation that is pressed halfway, and is used to indicate the timing of exposure control. In each of the shooting modes, when the shutter button 9 is not operated, an optical image of the subject is captured every 1/30 (second), and a live view image is displayed on the LCD 4. Further, in each of the above-described shooting modes, the imaging apparatus 1 is in an imaging standby state in which the shutter speed 9 and the aperture value are set in addition to the live view image display by performing a half-press operation of the shutter button 9. When the full-press operation is set and an exposure operation is performed, an exposure operation (hereinafter referred to as a main exposure operation) by the image sensor 11 described later for generating an image of a subject to be recorded on the memory card m is started.

  The imaging apparatus 1 according to the present embodiment is recorded in the memory card m during the main exposure operation when any one of the above-described shooting modes is set and the long-second monitoring mode described later is set. An image state (an image obtained by superimposing a subject state image obtained in each cycle) is displayed on the LCD 4 in real time as a live view image.

  The long-second monitoring switch 10 is used when the period of the main exposure operation is significantly longer than a preset display period (for example, 1/30 second) of the live view image when any of the above-described shooting modes is set. This is for setting a mode for displaying a live view image on the LCD 4 during the exposure operation period (long-second monitoring mode). Each time the button is pressed, setting / non-setting of the long-second monitoring mode is switched alternately.

  FIG. 3 is a block configuration diagram showing a system of the imaging apparatus 1. In the figure, the same members as those shown in FIGS. 1 and 2 are denoted by the same reference numerals.

  The imaging apparatus 1 includes an optical system 3, an LCD 4, an imaging device 11, a timing generator 12, a signal processing unit 13, an A / D conversion unit 14, an image memory 15, and a VRAM (Video Random Access Memory) 16. The operation unit 17 and the control unit 18 are provided.

  The optical system 3 corresponds to the optical system 3 shown in FIG. 1 and includes a mechanical shutter as described above. The LCD 4 corresponds to the LCD 4 shown in FIG.

  The imaging device 11 includes a plurality of photoelectric conversion elements, such as photodiodes, that are two-dimensionally arranged in a matrix. For example, R (red) and G (green) having different spectral characteristics are formed on the light receiving surface of each photoelectric conversion element. ), B (blue) color filter with Bayer arrangement in which color filters of 1: 2: 1 are arranged. Hereinafter, the photoelectric conversion element in which a color filter is provided is referred to as a pixel of the image sensor 11. The imaging device 11 converts the optical image of the subject formed by the optical system 3 into analog electrical signals (image signals) of R (red), G (green), and B (blue) color components. , B are output as image signals of respective colors.

  Although not described in detail, the image pickup device 11 is an interline type image pickup device including a light receiving unit made of a photodiode or the like, a vertical transfer unit, a horizontal transfer unit, and the like. The charge of each pixel is determined by a progressive transfer method. Is taken out. That is, the charges accumulated in each light receiving unit are transferred to the vertical transfer unit by a vertical synchronization signal, and the charges transferred to each vertical transfer unit are sequentially transferred from the pixels close to the horizontal transfer path by the horizontal synchronization signal to the horizontal transfer path. Is taken out as a pixel signal. The timing of starting and ending the imaging operation such as reading (horizontal synchronization and vertical synchronization) of the output signal of each pixel in the imaging device 11 and the exposure operation by the imaging device 11 is controlled by a timing generator 12 described later. The

  The image pickup apparatus 1 according to the present embodiment uses a long-second monitoring switch 10 to change the method for generating a recorded image depending on whether the long-second monitoring mode is set or not.

  That is, when the long-second monitoring mode is not set, if an instruction to start the main exposure operation (start generation of a recording pixel signal) is issued by fully pressing the shutter button 9, almost all the pixels of the image sensor 11 are Then, the exposure operation is continuously performed without taking out the pixel signal. For this reason, nothing is displayed on the LCD 4. After that, when the exposure time corresponding to the shutter speed calculated in advance elapses, the exposure operation is continued without taking out the pixel signal, so that the main exposure operation with almost all the pixels that have accumulated the charge is finished, and these exposure operations are completed. A pixel signal is extracted from the pixel, and a recorded image is generated using the extracted pixel signal.

  On the other hand, when the long second monitoring mode is set, if an instruction to start the main exposure operation is issued by starting the full pressing operation of the shutter button 9, pixel signals are extracted from almost all pixels of the image sensor 11 at a predetermined time interval. It is. The extracted pixel signals are sequentially added, and the pixel signals after the addition are stored in a second image storage unit 30 described later, and a live view image is sequentially generated using the pixel signals after the addition. . Thereby, the live view image is updated and displayed on the LCD 4 at regular time intervals. Thereafter, when the exposure time corresponding to the shutter speed calculated in advance elapses, the latest added image stored in the second image storage unit 30 is recorded in the memory card m as a recorded image.

  Based on the reference clock CLK0 transmitted from the control unit 18, the timing generator 12 controls the readout of the drive control signal for the image sensor 11, for example, the timing signal for integration start / end (exposure start / end), and the light reception signal of each pixel. A clock signal such as a signal (horizontal synchronization signal, vertical synchronization signal, etc.) is generated and output to the image sensor 11.

  The signal processing unit 13 performs predetermined analog signal processing on the analog pixel signal output from the image sensor 11. The signal processing unit 13 includes a CDS (correlated double sampling) circuit and an AGC (auto gain control) circuit. The CDS circuit reduces noise of the pixel signal. The AGC circuit Level adjustment is performed.

  In the present embodiment, the imaging apparatus 1 calculates the exposure time in advance so that the main exposure operation can be terminated at the photographer's intention and an image having the composition intended by the photographer can be obtained. In addition, the main exposure operation started by the full pressing operation of the shutter button 9 can be ended by the full pressing operation of the shutter button 9 again.

  The AGC circuit normally performs live by changing the gain in the amplification processing of the pixel value of the pixel signal (when the long-second monitoring mode is not set and before the main exposure operation is instructed when the long-second monitoring mode is set). The view image is always displayed with a constant brightness. When the long-second monitoring mode is set, the photographer visually recognizes the live view image displayed on the LCD 4 during the main exposure operation. Thus, the gain is fixed to a constant value during the period of the main exposure operation so that the timing at which a desired exposure amount can be obtained and the end of the main exposure operation can be instructed. As a result, as shown in FIG. 5, the live view image displayed on the LCD 4 becomes clear as time passes, and the exposure state of the image sensor 11 can be visually recognized. The gain setting by the AGC circuit is performed by a gain setting control unit 20 described later.

  The A / D conversion unit 14 converts the analog R, G, and B pixel signals output from the signal processing unit 13 into digital pixel signals composed of a plurality of bits, respectively.

  The image memory 15 is a memory that temporarily stores the pixel signal output from the A / D conversion unit 14 and is used as a work area for performing processing described later on the image signal by the control unit 18. .

  The VRAM 16 is a buffer memory for pixel signals of an image reproduced and displayed on the LCD 4, and has a pixel signal recording capacity corresponding to the number of pixels of the LCD 4.

  The operation unit 17 includes a switch for detecting a release operation of the shutter button 9, a mode setting switch 7, a quadruple switch 8, a long-second monitoring switch 10, and the like.

  The control unit 18 is composed of, for example, a microcomputer in which a storage unit (including first and second image storage units 29 and 30 described later) including a ROM that stores a control program and a RAM that temporarily stores data is incorporated. The drive of each member mentioned above is related and controlled.

  Here, the significance of displaying the live view image on the LCD 4 during the main exposure operation when the long second monitoring mode is set will be described.

  When the exposure time is long when the long-second monitoring mode is set, all pixel signals obtained by the exposure operation of the image sensor 11 performed after the start of the full-pressing operation of the shutter button 9 are used for recording on the memory card m. When configured to be used, since there is no pixel signal that can be used for live view image display, it is possible to display the state of the image recorded on the memory card m on the LCD 4 as a live view image during the main exposure operation. Can not.

  Further, even when the above-described configuration for displaying the live view image on the LCD 4 is provided during the main exposure operation, the configuration in which an image showing the state of the subject at each time point is displayed as a live view image is as follows. The following problems occur.

  FIG. 4 shows a live view image displayed on the LCD 4 at each time point in the 12-second period for three fireworks continuously launched for 12 seconds after the start of the main exposure operation. In FIG. 4, the state of the subject imaged 1/30 second before that is displayed as a live view image at each time point.

  In such a live view image display method, when the end of the main exposure operation is to be instructed at any timing within the 12 seconds, the fireworks locus is not displayed on the LCD 4 until the instructed timing. The person directly recognizes the state of the fireworks, and determines a subject image to be imaged at a timing when the desired state such as, for example, the state of the fireworks becomes the most vivid.

  However, in this case, it is unclear what image was obtained until a series of imaging operations of the imaging device 1 is completed, and the optical axis of the imaging device 1 is taken by taking a posture of directly viewing the subject. That is, the image recorded on the memory card m may differ greatly from the desired image due to factors such as a shift in the shooting range.

  In view of the above points, in the present embodiment, the imaging apparatus 1 is provided with the long-second monitoring mode as described above, and when the long-second monitoring mode is set, the period until the exposure time calculated in advance is passed. When the exposure time of the exposure operation is significantly longer than the display period (for example, 1/30 second) of the live view image, the live view image is displayed on the LCD 4 in real time during the main exposure operation period. It is assumed that the live view image displayed during this period displays the state of the image recorded on the memory card m.

  In order to realize such a configuration, as described above, when the long-second monitoring mode is set, an instruction to start a main exposure operation (start generation of a recording pixel signal) is issued by fully pressing the shutter button 9. When performed, pixel signals are extracted from almost all pixels of the image sensor 11 at a predetermined time interval (for example, 1/10 second). The extracted pixel signals are sequentially added, and the pixel signals after the addition are stored in the second image storage unit 30 and a live view image is sequentially generated using the pixel signals after the addition. As a result, live view images can be displayed on the LCD 4 at regular time intervals.

  For example, as shown in FIG. 5, 12 seconds after the start of the full-pressing operation of the shutter button 9, the image is superimposed as if the three fireworks launched with a time difference during the 12-second period were opened simultaneously. A live view image is generated, and the live view image is displayed on the LCD 4.

  Further, in the present embodiment, as described above, in order to be able to finish the main exposure operation at the photographer's intention, the main exposure operation started by the full pressing operation of the shutter button 9 is performed again. The main exposure operation can be completed by pressing the button 9 fully, and when the long second monitoring mode is set, the exposure time is calculated when the shutter button 9 is pressed halfway, regardless of the exposure time. The exposure operation of the image sensor 11 is automatically terminated when it is determined that an appropriate exposure amount has been obtained based on the pixel values of the pixel signals constituting the added image.

  Then, the imaging apparatus 1 is instructed to end the main exposure operation by a full-pressing operation of the shutter button 9 by the photographer again, or appropriate exposure based on the pixel value of the pixel signal constituting the added image. If it is determined that the amount has been obtained, the latest added image stored in the second image storage unit 30 is used as the recorded image.

  In order to realize the configuration as described above, as shown in FIG. 3, the control unit 18 functionally includes an exposure control unit 19, a gain setting control unit 20, a first imaging control unit 21, and a first recording control unit 22. , Addition processing unit 23, aspect correction processing unit 24, second imaging control unit 25, second recording control unit 26, recorded image generation unit 27, image processing unit 26, display control unit 27, image compression unit 28, first image A storage unit 29 and a second image storage unit 30 are provided.

  The exposure control unit 19 calculates an exposure control value (exposure value corresponding to the aperture value and shutter speed) based on the luminance of the image captured during the period when the shutter button 9 is half-pressed. .

  The gain setting control unit 20 performs gain setting for amplification processing by the AGC circuit of the signal processing unit 13. As described above, at the time of setting the long-second monitoring mode and during the main exposure operation, the gain setting control unit 20 sets the gain of amplification processing by the AGC circuit to a constant value. As a result, the exposure state of the image sensor 11 appears as the brightness of the live view image displayed on the LCD 4 as it is. That is, the live view image displayed on the LCD 4 becomes clear as time passes, and the exposure state of the image sensor 11 can be visually recognized on the LCD 4. The gain setting control unit 20 normally changes the gain according to the pixel value of the added image (when the long-second monitoring mode is not set and before the main exposure operation is instructed when the long-second monitoring mode is set). Yes.

  The first imaging control unit 21 performs the exposure operation on substantially all pixels in the image sensor 11 during the main exposure operation when the long second monitoring mode is set, and outputs a pixel signal at a predetermined cycle from all the pixels. The clock signal output from the timing generator 12 to the image sensor 11 is controlled so as to be output. Note that the first imaging control unit 21 causes all the pixels to perform the main exposure operation without taking out a pixel signal during the main exposure operation period when the long second monitoring mode is not set.

  When the long-second monitoring mode is set, the first recording control unit 22 temporarily outputs first pixel signals output from almost all pixels through the A / D conversion unit 14 and the like during the main exposure operation. It is recorded in the image storage unit 29.

  The addition processing unit 23 sets the long-second monitoring mode every time an image is recorded in the first image storage unit 29 by the first recording control unit 22 after the second period after the start of the main exposure operation. An added image obtained by adding these images is generated, and the added image is recorded in the first image storage unit 29. Assuming that an image made up of pixel signals obtained in the current cycle is represented as Pn (n = 1, 2,..., K−1, k), an exposure operation with almost all pixels and pixels obtained by this exposure operation. The added image Gn when the signal reading is repeated n times is Gn = P1 + P2 +... + Pn.

  When the addition image generated by the addition processing unit 23 is displayed on the LCD 4, the aspect correction processing unit 24 corrects the addition image to the aspect of the LCD 4 and records the aspect correction image in the second image storage unit 30. Is. As a result, when the long-second monitoring mode is set, a live view image (an image in which all moving object trajectories are displayed) can be displayed on the LCD 4 during the period of the main exposure operation and an image of the subject at each time point is superimposed. .

  The second imaging control unit 25 determines that the pixel value of the pixel signal constituting the addition image generated by the addition processing unit 23 has reached an appropriate value, or re-shoots the shutter button 9 by the photographer. When the end of the main exposure operation is instructed by the operation, the clock signal output from the timing generator 12 to the image sensor 11 is controlled so as to end the exposure operation of almost all pixels.

  The image processing unit 26 performs black level correction for correcting the black level to a reference black level for the added image subjected to the addition processing by the addition processing unit 23, R (red), White balance adjustment for level conversion of digital signals of G (green) and B (blue) color components, and correction of γ characteristics of digital signals of R (red), G (green), and B (blue) colors γ correction is performed.

  The display control unit 27 transfers pixel data of the image to the VRAM 16 so that the image output from the image processing unit 26 is displayed on the LCD 4. Thus, when the long second monitoring mode is not set, the period until the main exposure operation is started, and when the long second monitoring mode is set, the main exposure operation period is added to the period until the main exposure operation is started. Among them, the state of the subject (the state of the image recorded on the memory card m in the long-second monitoring mode) can be displayed on the LCD 4 in real time as a live view image.

  The image compression unit 28 uses the JPEG (Joint Picture Experts Group) method such as two-dimensional DCT (Discrete Cosine Transform) conversion and Huffman coding on the pixel data of the recorded image subjected to the above-described various processes by the image processing unit 26. Compressed image data is generated by performing a predetermined compression process, and an image file obtained by adding information (information such as a compression rate) relating to a captured image to the compressed image data is recorded in the memory card m.

  In the memory card m, image data is recorded in time series, and for each frame, the compressed image compressed by the JPEG method includes index information (frame number, exposure value, shutter speed, compression) about the captured image. Information such as rate, shooting date, flash on / off data at the time of shooting, and scene information).

  An imaging process at the time of setting the long-second monitoring mode, which is a characteristic part of the imaging apparatus 1 of the present embodiment, will be described with reference to a flowchart shown in FIG.

  As shown in FIG. 6, when the long-second monitoring switch 10 is turned on (YES in step # 1), the exposure controller 19 causes the shutter so that the exposure amount of the image sensor 11 becomes an appropriate value based on the luminance of the subject. The speed and aperture value are calculated (step # 2). When the calculated exposure time is equal to or longer than the predetermined value (YES in step # 3), the mode is set to the long second AE process (step # 4).

  When the shutter button 9 is fully pressed (YES in step # 5), the gain setting control unit 20 fixes the gain of amplification processing by the AGC circuit of the signal processing unit 13 to a constant value (step # 6). ). This is because, as described above, the live view image displayed on the LCD 4 becomes clear as time passes, and the exposure state of the image sensor 11 can be visually recognized. Then, the first imaging control unit 21 reads out pixel signals from almost all pixels of the imaging device 11, performs the above-described aspect correction (thinning) process, and starts generating a live view image (step # 7).

  When the first imaging control unit 21 reads out pixel signals from almost all pixels of the imaging element 11, the addition processing unit 23 sequentially outputs the pixel signals and pixel signals constituting the addition image generated in the previous cycle. The added image is displayed on the LCD 4 by the pixel signal after the addition process (step # 8).

  When the shutter button 9 is not fully depressed again, that is, when the end of the main exposure operation by the image sensor 11 is not instructed (NO in step # 9), the pixels constituting the generated live view image It is determined whether or not the pixel value of the signal has become an appropriate value (step # 10). As a result of the determination, when the pixel value of the pixel signal does not reach the appropriate value (NO in step # 10), pixel signals are read from substantially all pixels in the next cycle (step # 11), and step Returning to the process of # 8.

  On the other hand, when the pixel value of the pixel signal becomes the appropriate value in step # 10 (YES in step # 10), the latest added image is recorded as a recorded image on the memory card m (step # 12).

  In step # 9, when the full press operation of the shutter button 9 is performed again (YES in step # 9), the gain setting control unit 20 adds the added image stored in the second image storage unit 30 at that time. Is confirmed (step # 13), and the gain of amplification processing by the AGC circuit of the signal processing unit 13 is set to a gain that eliminates the difference between the pixel value and the appropriate value (step # 13). # 14). As a result, the pixel value of the pixel signal after addition obtained from substantially all the pixels when the full pressing operation of the shutter button 9 is performed again is amplified with the gain set in step # 14. Then, the image compression unit 28 records the recorded image subjected to the compression process on the memory card m (step # 11).

  When the exposure time calculated in step # 2 is less than the predetermined value (NO in step # 3), a mode for performing normal automatic exposure control (exposure operation based on the calculated exposure time) is set. The exposure time is temporarily stored (step # 15). Then, while the shutter button 9 is not fully pressed (NO in step # 16), the processes of steps # 2, # 3, and # 15 are repeated, and the shutter button 9 is fully pressed. (YES in step # 16), the second imaging control unit 25 performs the exposure operation of the image sensor 11 for the exposure time calculated in step # 2 (step # 17), and outputs the pixel signal obtained by this exposure operation. Recording is performed on the memory card m (step # 18).

  After the processing of step # 12 or # 18, it is determined whether or not imaging is continued (step # 19). If imaging is continued (YES in step # 19), the process returns to step # 2. On the other hand, if imaging is not continued (NO in step # 19), imaging is terminated (step # 20).

  As described above, when the long-second monitoring mode is set, the period of the main exposure operation is configured by reading out pixel signals from almost all pixels, adding each time the pixel signals are read out, and adding the pixel signals. Since the image is displayed on the LCD 4, the image obtained by the exposure can be visually recognized during the long exposure period.

  In addition, since exposure control is performed based on the pixel value of the added pixel signal, a recorded image with appropriate brightness can be obtained.

  In addition, since the pixel signal is amplified with a constant gain during the period of the main exposure operation when the long second monitoring mode is set, the live view image displayed on the LCD 4 becomes clear as time passes, and the image sensor 11 The exposure state can be visually confirmed.

  In addition, a function for ending the main exposure operation is provided by performing the full press operation of the shutter button 9 again during the main exposure operation, so that the main exposure operation can be ended at the intention of the photographer. The image of the composition (image of the composition intended by the photographer) can be obtained.

  Note that the present invention is not limited to the above-described embodiment, and the following modifications (1) to (7) can also be employed.

  (1) In the above-described embodiment, the live view image displayed on the LCD 4 becomes clear as time passes and the exposure state of the image sensor 11 is visually recognized during the main exposure operation when the long second monitoring mode is set. The gain of the pixel signal is fixed to a constant value so that the image pickup device 11 can be recognized. However, the present invention is not limited to this, and the exposure state of the image sensor 11 can be recognized by the photographer by the following configuration. it can.

  As shown in FIG. 7, a bar display unit 31 extending in the vertical direction is provided on the right side of the display screen of the LCD 4, and the exposure amount of the pixel derived based on the pixel signal constituting the added image is displayed as a bar. This is represented by the length of the bar B displayed on the part 31. When the length of the bar B is the longest, it indicates that the pixel exposure amount has reached an appropriate value. In this case, the control unit 18 displays the exposure amount deriving unit for deriving the exposure amount of the pixel based on the pixel signal constituting the added image and the exposure amount (exposure state) derived by the exposure amount deriving unit on the LCD 4. It is good to provide the exposure condition display control part displayed by display.

  As another form of displaying the exposure state of the image sensor 11 on the LCD 4, for example, two lighting sections having different display forms depending on written characters, colors, etc. are provided, and while the exposure amount of the pixel does not reach an appropriate value, Only the lighting section is lit, and when the exposure amount reaches an appropriate value, the other lighting section is switched to lighting to visually notify the photographer that the exposure status has become appropriate. You may make it do.

  (2) In the above embodiment, pixel signals are extracted from almost all pixels at preset time intervals, an added image is generated from these pixel signals, and is displayed on the LCD 4 as a live view image. The time interval for extracting pixel signals from substantially all the pixels may be set as follows.

  For example, when the set exposure time is in the range from 1 (s) to 2 (s), the time interval for extracting pixel signals from almost all pixels is set to 1/10 (s), and the calculated exposure is performed. When the time is in the range from 2 (s) to 5 (s), the time interval is set to 1/5 (s), and the calculated exposure time is in the range from 5 (s) to 10 (s). Is set to 1/3 (s), and when the calculated exposure time is 15 (s) or more, the time interval is set to 1/2 (s).

  In this way, the longer the set exposure time, the less the subject moves, so the longer the exposure time, the longer the time interval for extracting pixel signals from almost all pixels. This makes it easy to grasp the timing at which exposure should be finished to reduce the exposure error, and so-called offset (the black level (optical black) shift due to dark current (charge generated even when no light is applied to the image sensor)) ) And the power consumption required for displaying the live view image can be realized in a balanced manner. This process may be performed between the process of step # 6 and the process of # 7 in the flowchart shown in FIG.

  Further, with respect to this setting method, it is easier to grasp the timing at which the exposure should be ended, and the exposure error is further reduced. For example, among the exposure times set as described above, for example, the set exposure time Is in the range from 2 (s) to 5 (s), the time interval for extracting pixel signals from almost all pixels is 1/5 (s) in the first half period and 1/10 ( s), and when the set exposure time is in the range of 5 (s) to 10 (s), the first 1/3 period is set to 1/3 (s). The next 1/3 period is set to 1/5 (s), the last 1/3 period is set to 1/10 (s), and the set exposure time is in the range of 15 (s) or more. Sometimes the first ½ period of the time interval is ½ (s) and the next ¼ Period to 1/3 (s), the last quarter of the period may be set respectively to 1/10 (s).

  These time intervals may be set manually by, for example, the quadruple switch 8 or may be displayed in the image pickup apparatus 1 when the image signal is obtained by pressing the shutter button 9 halfway before the main exposure operation. May be automatically set based on the luminance of the subject calculated from the pixel signals constituting the live view image).

  (3) In the above embodiment, the case has been described in which the imaging apparatus 1 is set to the long-second monitoring mode in each of the above-described shooting modes. However, when the bulb shooting mode can be set, the bulb shooting mode is set. However, even when the long-second monitoring mode is set, during the main exposure operation, pixel signals are read from almost all pixels and added as described above, and the added image obtained by the addition processing is displayed live. While being displayed as a view image, an added image obtained at the end of the main exposure operation may be recorded on the memory card m as a recorded image.

  The bulb photographing mode is a mode for performing bulb photographing in which the photographer instructs the opening / closing timing of the mechanical shutter with the shutter button 9, and recording by the image sensor 11 is performed by the electronic shutter when the shutter button 9 is fully pressed. Is a mode in which the exposure operation is ended by releasing the shutter button 9 and releasing the full press of the shutter button 9, and the exposure operation is ended for a relatively long time (for example, 10 seconds). The subject can be photographed with exposure.

  (4) In the above embodiment, the LCD 4 is provided to display the image of the subject, and the live view image or the like is displayed on the LCD 4. However, the present invention is not limited to this, and an electronic viewfinder is provided instead of the optical viewfinder 5. In such a case, the live view image may be displayed on the electronic viewfinder.

  (5) In the above embodiment, the progressive transfer type image sensor is adopted from the viewpoint of easy generation of the drive control signal for driving the image sensor, but the image pickup apparatus adopts the interlace transfer type image sensor. The present invention can also be applied.

  (6) In the above embodiment, the memory card m is used as a means for recording an image. However, the present invention is not limited to this, and the imaging apparatus 1 is connected to a device having a storage capacity such as a computer, a communication cable, or a communication network. If it is configured to be communicable via a computer, an image may be recorded on a device such as the computer.

  (7) In the above-described embodiment, a CCD in which primary color filters (color filters of R (red), G (green), and B (blue)) are disposed on the light receiving surface of each photoelectric conversion element is employed as the image sensor 11. However, the present invention is not limited to this, and a CCD provided with complementary color filters (C (cyan), M (magenta), Y (yellow)) may be employed.

It is a front view of the imaging device concerning the present invention. It is a rear view of the imaging device concerning the present invention. It is a block block diagram which shows the system of an imaging device. It is a figure which shows an example of the conventional live view image. It is a figure which shows an example of the live view image displayed in the imaging device which concerns on this invention. It is a flowchart which shows the imaging process at the time of the setting of the long second monitoring mode of an imaging device. It is a figure which shows the other display form of the pixel value of an addition image.

Explanation of symbols

1 Imaging device 4 LCD
9 Shutter Button 10 Long Second Monitoring Switch 11 Image Sensor 12 Timing Generator 18 Control Unit 19 Exposure Control Unit 20 Gain Setting Control Unit 21 First Imaging Control Unit 22 First Recording Control Unit 23 Addition Processing Unit 24 Aspect Correction Processing Unit 25 Second Imaging control unit 26 Image processing unit 27 Display control unit 28 Image compression unit 29 First image storage unit 30 Second image storage unit

Claims (5)

An image sensor comprising a plurality of types of pixels that receive different colors, and
An input operation unit for instructing the image sensor to start an exposure operation for generating a recording pixel signal to be recorded in a predetermined recording unit;
When the exposure start instruction is performed by the input operation unit, an imaging control unit that outputs a pixel signal at a predetermined time interval to substantially all of the plurality of pixels of the imaging element;
An addition processing unit that sequentially adds pixel signals obtained from substantially all the pixels every predetermined time;
A recording unit that records pixel signals sequentially generated by the addition processing by the addition processing unit;
An image display apparatus, comprising: an image display unit that updates and displays pixel signals sequentially generated by the addition processing by the addition processing unit as a display image. An exposure condition deriving unit for deriving an exposure condition of the image sensor based on pixel signals sequentially generated by the addition process;
The imaging apparatus according to claim 1, further comprising: an exposure status display control unit configured to display the derived exposure status of the imaging element on the image display unit in synchronization with the display processing of the display image. An amplification unit that amplifies a pixel value of a pixel signal output from a pixel of the image sensor and outputs the amplified pixel value to the addition processing unit;
A mode switching control unit for switching a mode between a first amplification mode in which an amplification factor of amplification processing by the amplification unit is constant and a second amplification mode in which the amplification factor is changed;
When the exposure start instruction is given by the input operation unit, the mode switching control unit sets the first amplification mode, and the image display unit is configured by the pixel signal amplified at the constant amplification factor. The image pickup apparatus according to claim 1, wherein an image to be displayed is displayed.   The imaging apparatus according to claim 1, further comprising an input operation unit for inputting an instruction to cause the image display unit to perform display processing of the display image. A mode setting unit that sets a bulb photographing mode that allows an instruction to start and end an exposure operation by the image sensor to generate the recording pixel signal;
An exposure time calculation unit that calculates the exposure time based on the luminance of the subject,
The image display unit performs display processing of the display image when the bulb setting mode is set by the mode setting unit or when the exposure time calculated by the exposure time calculation unit is longer than a predetermined time. The imaging apparatus according to any one of claims 1 to 3.

Images