Source: https://patents.google.com/patent/JP5226552B2/en
Timestamp: 2020-08-10 00:40:23
Document Index: 36920107

Matched Legal Cases: ['art 2', 'art 10', 'art 11', 'art 12', 'art 21', 'art 23', 'art 24', 'art 25', 'art 26', 'art, 1', 'art, 2']

JP5226552B2 - Imaging device - Google Patents
JP5226552B2
JP5226552B2 JP2009023034A JP2009023034A JP5226552B2 JP 5226552 B2 JP5226552 B2 JP 5226552B2 JP 2009023034 A JP2009023034 A JP 2009023034A JP 2009023034 A JP2009023034 A JP 2009023034A JP 5226552 B2 JP5226552 B2 JP 5226552B2
JP2010183195A (en
2009-02-03 Application filed by オリンパスイメージング株式会社, オリンパス株式会社 filed Critical オリンパスイメージング株式会社
238000003384 imaging method Methods 0.000 title claims description 119
238000006243 chemical reaction Methods 0.000 claims description 96
The present invention relates to an imaging apparatus capable of acquiring still image recording image data and image display image data.
An imaging device such as a digital camera or a digital video camera is equipped with an imaging device that converts an optical image into an electrical signal. In recent years, the market share of this imaging device is shifting from CCD to CMOS.
A MOS type image pickup device such as a CMOS mounted on the image pickup apparatus sequentially reads out the charges of a large number of pixels arranged in a two-dimensional manner on the image pickup surface. Is different for each pixel (or for each line). Therefore, the MOS type image pickup device configured so that the exposure start time of all the pixels can be made the same and the exposure end time of all the pixels can be made the same (that is, control by the global shutter can be performed) In addition to a photoelectric conversion unit such as a photodiode that generates a signal corresponding to the exposure amount, a signal storage unit that temporarily stores signal charges generated in the photoelectric conversion unit, and when transferring or resetting charges In this configuration, a transistor functioning as a switch is provided.
An example of the configuration of the pixel of such an image sensor includes a configuration in which five transistors are provided in one pixel as shown in FIG. 3 according to the embodiment of the present invention. The configuration as shown in FIG. 3 enables control by a global shutter using the signal storage unit FD as an in-pixel memory. For example, Japanese Patent Application Laid-Open No. 2005-65184 discloses a technique for driving in the following sequence in order to suppress KTC noise (reset noise) when this image sensor is used in a digital camera.
(1) The signal storage unit FD is reset by the transistor Mr, and the reset data is sequentially scanned and read for each line and stored.
(2) The photoelectric conversion units PD of all the pixels are collectively reset, and after a predetermined exposure time has elapsed, the pixel data of the photoelectric conversion units PD are collectively transferred to the signal storage unit FD.
(3) The pixel data transferred to the signal accumulation unit FD is sequentially scanned and read for each line, and the reset data stored in (1) is subtracted (takes a difference).
JP 2005-65184 A
However, when the image sensor is driven in the sequence as described above, the live view (image display) cannot be updated during a series of operations for obtaining an image, and the same image is displayed on the display unit. The phenomenon that the display is continued or the display portion is blacked out and the image is not displayed occurs.
In particular, in the above-described sequence, both the all-pixel signal readout operation for reset data before exposure and the all-pixel signal readout operation for pixel data after exposure are necessary, so that one sequence period is long. Will be. In particular, recent image sensors tend to have a longer period during which images for live view cannot be acquired because the number of pixels increases and the time required to read out all pixel signals tends to increase. It is becoming an important issue.
In addition, the live view image is used not only for display on the display unit but also for autofocus (AF), automatic exposure control (AE), and the like. It is desirable to be able to acquire the image.
The present invention has been made in view of the above circumstances, and an object thereof is to provide an imaging apparatus capable of shortening a time during which a live view image is not updated when a still image is captured.
In order to achieve the above object, an imaging apparatus according to a first aspect of the present invention includes a pixel unit in which pixels including a photoelectric conversion unit that generates a signal charge corresponding to an exposure amount are two-dimensionally arranged, and A reset unit that collectively resets the photoelectric conversion unit, an exposure control unit that controls the photoelectric conversion unit to be exposed for a predetermined time from the reset by the reset unit, and a signal charge generated by the photoelectric conversion unit The first charge storage unit shielded from light and the signal charge of a predetermined pixel group among the signal charges stored in the first charge storage unit are transferred to other pixel groups. A first signal charge readout unit that reads out the signal charges before the signal charges, and then reads out the signal charges of the other pixel groups, and for recording a still image based on the signal charges read out by the first signal charge readout unit. The first image data of And a second signal for reading the signal charges generated by the predetermined pixel group one or more times within a time interval for reading the signal charges of the other pixel group by the first image processing unit and the first signal charge reading unit. A charge reading unit; a second image processing unit for generating second image data for image display based on the signal charge read by the second signal charge reading unit; and the first image for recording a still image. A camera control unit for controlling whether data is acquired by single shooting or continuous shooting, and when acquiring data by single shooting, the second signal charge reading unit and the second image When acquiring by continuous shooting without performing the operation of the processing unit, the operation of the second signal charge reading unit and the second image processing unit is performed .
An imaging apparatus according to a second aspect of the present invention collectively resets a pixel unit in which pixels including a photoelectric conversion unit that generates a signal charge according to an exposure amount are arranged in a two-dimensional manner, and the photoelectric conversion unit. A reset unit, an exposure control unit that controls the photoelectric conversion unit to be exposed for a predetermined time from a reset by the reset unit, and a unit that collectively transfers and accumulates signal charges generated by the photoelectric conversion unit The signal charges of a predetermined pixel group out of the signal charge accumulated in the first charge accumulation unit and the first charge accumulation unit that are shielded from light are read before the signal charges of the other pixel groups, and then In addition, a first signal charge reading unit for reading signal charges of the other pixel group and a first image data for still image recording are generated based on the signal charges read by the first signal charge reading unit. An image processing unit; A second signal charge reading unit that reads the signal charge generated by the predetermined pixel group one or more times within a time interval in which the signal charge of the other pixel group is read by the one signal charge reading unit; and the second signal charge A second image processing unit that generates second image data for image display based on the signal charge read by the reading unit, wherein the pixel functions as the photoelectric conversion unit and the reset unit. A first transistor for transferring, a second transistor for transferring the charge generated by the photoelectric conversion unit to the first charge storage unit, and for transferring and storing the charge stored in the first charge storage unit A light-shielded second charge storage unit, a third transistor for transferring the charge stored in the first charge storage unit to the second charge storage unit, and resetting the second charge storage unit The A fourth transistor, a fifth transistor for amplifying the voltage of the second charge storage unit, and a sixth transistor for selecting an output signal of the fifth transistor, and the imaging device includes: A reset signal reading unit that reads a voltage of the second charge storage unit when the second charge storage unit is reset by the fourth transistor as a reset signal after exposing the photoelectric conversion unit; The image processing unit generates the first image data based on a difference between the signal charge read by the first signal charge reading unit and the reset signal read by the reset signal reading unit, At least from the batch reset of the photoelectric conversion unit by the first transistor to the end of reading of the signal charge by the first signal charge reading unit. The image processing apparatus further includes a blur correction unit that reduces the blur of the optical image exposed to the element part.
An imaging apparatus according to a third aspect of the present invention collectively resets a pixel unit in which pixels including a photoelectric conversion unit that generates a signal charge corresponding to an exposure amount are arranged in a two-dimensional manner, and the photoelectric conversion unit. A reset unit, an exposure control unit that controls the photoelectric conversion unit to be exposed for a predetermined time from a reset by the reset unit, and a unit that collectively transfers and accumulates signal charges generated by the photoelectric conversion unit The signal charges of a predetermined pixel group out of the signal charge accumulated in the first charge accumulation unit and the first charge accumulation unit that are shielded from light are read before the signal charges of the other pixel groups, and then In addition, a first signal charge reading unit for reading signal charges of the other pixel group and a first image data for still image recording are generated based on the signal charges read by the first signal charge reading unit. An image processing unit; A second signal charge reading unit that reads the signal charge generated by the predetermined pixel group one or more times within a time interval in which the signal charge of the other pixel group is read by the one signal charge reading unit; and the second signal charge A second image processing unit that generates second image data for image display based on the signal charge read by the reading unit, wherein the pixel functions as the photoelectric conversion unit and the reset unit. A second transistor for transferring the charge generated by the photoelectric conversion unit to the first charge storage unit, a third transistor for resetting the first charge storage unit, and the first transistor A fourth transistor for amplifying the voltage of one charge storage unit; and a fifth transistor for selecting an output signal of the fourth transistor, wherein the imaging device includes the third transistor A reset signal reading unit that reads out a voltage of the first charge storage unit when the first charge storage unit is reset by a transistor as a reset signal before exposing the photoelectric conversion unit; Generates the first image data based on the difference between the signal charge read by the first signal charge reading unit and the reset signal read by the reset signal reading unit, and at least the From the start of resetting of the first charge storage unit by the third transistor to the end of reading of the signal charge by the first signal charge reading unit, a blur correction unit that reduces blurring of the optical image exposed to the pixel unit Is further provided.
An imaging device according to a fourth aspect of the present invention collectively resets a pixel unit in which pixels including a photoelectric conversion unit that generates a signal charge corresponding to an exposure amount are arranged in a two-dimensional manner, and the photoelectric conversion unit. A reset unit, an exposure control unit that controls the photoelectric conversion unit to be exposed for a predetermined time from a reset by the reset unit, and a unit that collectively transfers and accumulates signal charges generated by the photoelectric conversion unit The signal charges of a predetermined pixel group out of the signal charge accumulated in the first charge accumulation unit and the first charge accumulation unit that are shielded from light are read before the signal charges of the other pixel groups, and then In addition, a first signal charge reading unit for reading signal charges of the other pixel group and a first image data for still image recording are generated based on the signal charges read by the first signal charge reading unit. An image processing unit; A second signal charge reading unit that reads the signal charge generated by the predetermined pixel group one or more times within a time interval in which the signal charge of the other pixel group is read by the one signal charge reading unit; and the second signal charge A second image processing unit that generates second image data for image display based on the signal charges read by the reading unit, a photographing lens, an AF control unit that performs autofocus control on the photographing lens, and a still image When acquiring the first image data for recording, including a camera control unit for controlling the AF control unit by either single AF or continuous AF, and performing control by single AF In the case where the second signal charge reading unit and the second image processing unit are not operated and controlled by continuous AF, the second signal charge reading unit and the second image charge reading unit It performs an operation of second image processing section.
According to the imaging apparatus of the present invention, it is possible to reduce the time during which a live view image is not updated when capturing a still image.
1 is a block diagram illustrating a configuration of an imaging apparatus according to Embodiment 1 of the present invention. FIG. 3 is a diagram illustrating a more detailed configuration of an imaging unit in the first embodiment. FIG. 3 is a circuit diagram illustrating in more detail a configuration example of a pixel in a pixel portion of the image sensor of the first embodiment. In the said Embodiment 1, the figure which shows the structure of the pixel in a semiconductor substrate in a substrate thickness direction. 4 is a timing chart illustrating a global shutter operation of the imaging apparatus according to the first embodiment. FIG. 3 is a diagram showing an example of lines read for use in live view in the pixel unit of the first embodiment. FIG. 4 is a diagram illustrating an example when a still image is captured by driving an imaging unit by a first driving method during live view in the first embodiment. FIG. 4 is a diagram illustrating an example when a still image is captured by driving the imaging unit with a second driving method during live view in the first embodiment. FIG. 10 is a diagram illustrating another example of capturing a still image by driving the imaging unit with the second driving method during live view in the first embodiment. The timing chart which shows the process shown in FIG. 7 of the said Embodiment 1 in detail. FIG. 9 is a timing chart showing an example of processing for acquiring LV image data only in a reset data reading period in the processing shown in FIG. 8 of the first embodiment. 9 is a timing chart showing a more detailed example of the process shown in FIG. 8 of the first embodiment. 6 is a flowchart illustrating processing according to a shooting mode of the imaging apparatus according to the first embodiment. 6 is a flowchart illustrating processing according to an AF mode of the imaging apparatus according to the first embodiment. The circuit diagram which shows the structural example of the pixel in the pixel part of the image pick-up element of Embodiment 2 of this invention. In the said Embodiment 2, a timing chart which shows the operation | movement when an imaging part is driven with the 1st drive method, and the still image by a global shutter is imaged. In the said Embodiment 2, the figure which shows the example when driving an imaging part with the 2nd drive method in the middle of performing live view, and images a still image. The figure which shows the structure of the imaging part in Embodiment 3 of this invention. FIG. 5 is a circuit diagram illustrating a configuration example of a pixel in a pixel portion of the imaging element according to the third embodiment. In the said Embodiment 3, a timing chart which shows the 1st example of operation when an imaging part is driven with the 2nd drive method, and the still image by a global shutter is imaged. In the said Embodiment 3, the timing chart which shows the 2nd operation example when the imaging part is driven with the 2nd drive method, and the still image by a global shutter is imaged. FIG. 6 is a circuit diagram illustrating a configuration example of a pixel in a pixel portion of an image sensor according to a fourth embodiment of the present invention. In the said Embodiment 4, the figure which shows the example when driving an imaging part with the 2nd drive method in the middle of performing live view, and images a still image.
1 to 14 show Embodiment 1 of the present invention, and FIG. 1 is a block diagram showing a configuration of an imaging apparatus.
As shown in FIG. 1, the imaging apparatus includes a lens 1, an imaging unit 2, an image processing unit 3, an AF evaluation value calculation unit 4, a display unit 5, a camera shake detection unit 7, and a camera shake correction unit 8. An exposure control unit 9, an AF control unit 10, a camera operation unit 11, and a camera control unit 12. In addition, although the memory card 6 is also described in the drawings, the memory card 6 is configured to be detachable from the imaging device, and therefore, the configuration may not be unique to the imaging device.
The lens 1 is a photographing lens for forming an optical image of a subject on an imaging surface of an imaging element 21 (see FIG. 2) of the imaging unit 2.
The imaging unit 2 photoelectrically converts an optical image of a subject formed by the lens 1 and converts it into a digital signal as will be described later, and then outputs it. The imaging unit 2 is configured to be able to perform at least an operation by a global shutter having the same exposure start time and exposure end time for all pixels (in addition to this, for example, in line units (or pixel units)). It may be configured to be able to perform an operation by a rolling shutter that performs sequential exposure).
The image processing unit 3 performs various digital image processing on the image signal output from the imaging unit 2. The image processing unit 3 includes a first image processing unit 3a that processes image data for recording, and a second image processing unit 3b that also processes image data for display (also serves as a third image processing unit). ing.
The AF evaluation value calculation unit 4 calculates an AF evaluation value indicating the degree of focus on the subject based on an image signal output from the imaging unit 2 (for example, a luminance signal (or luminance equivalent signal) in the image signal). It is to calculate. The AF evaluation value calculated by the AF evaluation value calculation unit 4 is output to the camera control unit 12.
The display unit 5 displays an image on the basis of a signal image-processed for display by the second image processing unit 3b of the image processing unit 3. The display unit 5 can reproduce and display a still image, and can perform live view (LV) display that displays an imaging range in real time.
The memory card 6 is a recording medium for storing a signal image-processed for recording by the first image processing unit 3a of the image processing unit 3.
The camera shake detection unit 7 detects camera shake of the imaging apparatus.
The camera shake correction unit 8 drives the lens 1 and the imaging unit 2 so as to cancel the influence of the camera shake on the captured image based on the camera shake information detected by the camera shake detection unit 7 (shake correction unit). It is.
The exposure control unit 9 drives the imaging unit 2 based on a command from the camera control unit 12 to perform exposure control.
The AF control unit 10 drives the focus lens included in the lens 1 based on the control of the camera control unit 12 that has received the AF evaluation value from the AF evaluation value calculation unit 4, and the subject image formed on the imaging unit 2 Is to be focused.
The camera operation unit 11 is for performing various operation inputs to the imaging apparatus. Examples of operation members included in the camera operation unit 11 include a power switch for turning on / off the power of the imaging apparatus, a release button including a two-stage press button for inputting an instruction for still image shooting, and a shooting mode. Shooting mode switch for switching between single shooting mode and continuous shooting mode, and AF mode switch for switching AF mode between single AF mode and continuous AF mode.
Based on the AF evaluation value from the AF evaluation value calculation unit 4, camera shake information from the camera shake detection unit 7, operation input from the camera operation unit 11, and the like, the camera control unit 12 performs image processing unit 3, memory card 6, camera shake, and the like. The entire imaging apparatus including the correction unit 8, the exposure control unit 9, the AF control unit 10 and the like is controlled.
Next, FIG. 2 is a diagram illustrating a more detailed configuration of the imaging unit 2.
The imaging unit 2 includes an imaging device 21 configured as, for example, a MOS solid-state imaging device, an A / D conversion unit 22, and a KTC noise removal unit 23.
Among these, the imaging device 21 includes a pixel unit 24, a CDS unit 25, a vertical control circuit 26, and a horizontal scanning circuit 27.
The pixel unit 24 is configured by two-dimensionally arranging a plurality of pixels 28 in the row direction and the column direction.
The vertical control circuit 26 applies various signals to the pixels arranged in the pixel unit 24 in units of rows (lines), and serves as a vertical scanning circuit, a reset control unit, and a signal readout control unit. Yes. A signal from a pixel in a row selected by the vertical control circuit 26 is output to a vertical transfer line VTL (see FIG. 3) provided for each column.
The CDS unit 25 performs correlated double sampling on the pixel signal transferred from the vertical transfer line VTL when the imaging unit 2 is operated by the rolling shutter.
The horizontal scanning circuit 27 takes in a pixel signal of one row that is selected by the vertical control circuit 26 and transferred from the vertical transfer line VTL through the CDS unit 25 with or without CDS, and the pixel signal of that row. Are output in time series in the order of the horizontal pixel arrangement.
The A / D converter 22 converts the analog image signal output from the image sensor 21 into a digital image signal.
The KTC noise removal unit 23 performs a KTC noise removal process on the digital image signal output from the A / D conversion unit 22 when the imaging unit 2 operates with a global shutter.
Next, FIG. 3 is a circuit diagram illustrating in more detail a configuration example of the pixel 28 in the pixel unit 24 of the image sensor 21.
In FIG. 3, PD (photodiode) is a photoelectric conversion unit, and FD (floating diffusion) is a signal storage unit (storage unit, first charge storage unit) that temporarily holds a signal of the photoelectric conversion unit PD.
Mtx2 is a transistor that functions as a first reset unit that resets the photoelectric conversion unit PD, and is connected to a current source VDD and to a signal line TX2 for applying a PD reset pulse.
Mtx1 is a transistor that functions as a transfer unit and a gate unit for transferring the signal of the photoelectric conversion unit PD to the signal storage unit FD, and is connected to a signal line TX1 for applying a transfer pulse.
Ma is an amplifying transistor that functions as an amplifying unit, and forms a source follower amplifier with the current source VDD. The signal in the signal storage unit FD is amplified by the amplifying transistor Ma, and functions as a signal charge reading unit (first signal charge reading unit, second signal charge reading unit, reset signal reading unit, third signal charge reading unit). It is output to the vertical transfer line VTL via the selection transistor Mb. The selection transistor Mb is connected to a signal line SEL for applying a selection pulse.
Mr is a transistor that functions as a second reset unit that resets the signal storage unit FD and the input unit of the amplifying transistor Ma, and is connected to a signal line RES for applying an FD reset pulse. If the transfer pulse is applied to the transistor Mtx1 and the FD reset pulse is applied to the transistor Mr at the same time, the signal storage unit FD can be reset, and at the same time, the photoelectric conversion unit PD. Can be reset. Therefore, the combination of the transistor Mtx1 and the transistor Mr functions also as a first reset unit for the photoelectric conversion unit PD.
Next, FIG. 4 is a diagram showing the configuration of the pixel 28 in the semiconductor substrate in the substrate thickness direction.
In the example shown in FIG. 4, a P-type substrate is used as the semiconductor substrate.
The photoelectric conversion part PD is formed as an n− region, and a p region is formed on the wiring layer side. The signal line TX2 is connected to the p region. As a result, the photoelectric conversion portion PD is formed as a buried type, and the dark current can be reduced. Further, the substrate surface other than the portion corresponding to the photoelectric conversion portion PD is shielded from light by a light shielding film having a predetermined light shielding performance.
The signal accumulation unit FD is formed as an n + region at a predetermined interval from the photoelectric conversion unit PD. This n + region is connected to the amplification transistor Ma side. Thus, since the signal storage unit FD is directly connected to the wiring layer, it is difficult to reduce the dark current.
Further, a gate electrode is formed on the substrate surface between the photoelectric conversion unit PD and the signal storage unit FD, and the transistor Mtx1 is configured. The gate electrode of the transistor Mtx1 is connected to the signal line TX1.
Further, another n + region is formed at a position spaced apart from the n + region constituting the signal storage unit FD by a predetermined distance, and the current source VDD is connected to the latter n + region. A gate electrode is formed on the surface of the substrate between these two n + regions, thereby forming a transistor Mr. The gate electrode of the transistor Mr is connected to the signal line RES.
Next, FIG. 5 is a timing chart showing the global shutter operation of the imaging apparatus.
Before performing exposure by the global shutter operation, first, in the reset data reading period, the signal storage unit FD is reset and reset noise is read. That is, first, a reset pulse is applied from the signal line RES to the transistors Mr of the pixels 28 arranged in the first row of the pixel unit 24 to reset the signal accumulation unit FD in the first row. Further, by applying a selection pulse from the signal line SEL to the selection transistor Mb of each pixel 28 arranged in the first row of the pixel unit 24, the reset noise is read out from the signal accumulation unit FD in the first row. Do.
By sequentially performing such an operation from the first row to the n-th row (final row) of the pixel unit 24, the reset noise of all the pixels is read out. The reset noise read out here is stored in the KTC noise removal unit 23 through the CDS unit 25 (without CDS operation), the horizontal scanning circuit 27, and the A / D conversion unit 22 in this order.
Next, at the time of this global shutter operation, by simultaneously turning off the transistors Mtx2 of all the pixels of all the lines via the signal line TX2, accumulation of charges in the photoelectric conversion units PD of all the pixels is started, that is, all the pixels Are simultaneously started.
When a predetermined exposure period (this exposure period corresponds to the shutter speed determined by the AE calculation) has elapsed since the start of exposure, a transfer pulse is transmitted to the transistors Mtx1 of all pixels of all lines via the signal line TX1. Are simultaneously applied, the charges accumulated in the photoelectric conversion unit PD are transferred to the signal accumulation unit FD, that is, the exposure of all the pixels is completed simultaneously.
Thereafter, the pixel data reading period starts, and the electric charge accumulated in the signal accumulation unit FD passes through the amplification transistor Ma and the selection transistor Mb from the first row to the n-th row (final row). Toward the vertical transfer line VTL in line units.
At least from the start of the reset data reading period (at the start of resetting by the transistor Mr as the second reset unit) to the end of the pixel data reading period, the camera shake correction unit 8 based on the detection result of the camera shake detection unit 7 Correction is made. The reason for performing camera shake correction in this way is that when there is a high-brightness subject in the object field, the range of influence due to leakage light or leakage current in the high-brightness part at the position where the high-brightness subject is imaged expands. This is to prevent it.
That is, it is considered that a normal high-brightness subject has an upper limit of a BV value of about 12 to 13, for example, and the light-shielding performance of the light-shielding film of the image sensor 21 can also shield light from such a high-brightness subject. Designed to. On the other hand, when the subject is, for example, the sun, the BV value may reach 27, and it can be said that the subject is a high-intensity subject that exceeds the normally conceivable range. In such a case, even if the signal storage unit FD is shielded by the light shielding film, it must be considered that a certain amount of leakage light or leakage current is generated. If this occurs, there is a possibility that the influence of leakage light or leakage current spreads over a wide range.
Therefore, as shown in FIG. 5, at least from the start of the reset data reading period (at the start of resetting by the second reset unit) to the end of the pixel data reading period, camera shake correction based on the detection result of the camera shake detecting unit 7 The camera shake correction by the unit 8 is performed. Thereby, it is possible to suppress the influence of leakage light and leakage current and to prevent image quality from further deteriorating.
Next, FIG. 6 is a diagram illustrating an example of lines read out for use in the live view in the pixel unit 24.
In the example shown in FIG. 6, the total number of lines configured in the pixel unit 24 is 1200 lines. An example is shown in which pixel data for live view (LV) is read out from all these lines at a rate of one line per six lines. However, when the image pickup device 21 is a single-plate color image pickup device, for example, a Bayer array color filter is arranged on the front surface of the pixel unit 24. In this case, since the color components to be generated are only G and R, or only G and B, here, as odd lines for LV, (12m-6) lines (where m is 1 to 3) in all the lines. 100 (integer of 100) is read out, and (12m-1) lines (where m is an integer of 1 to 100) of all the lines are read out as even lines for LV, thereby obtaining all RGB color components. To be able to
Next, FIG. 7 is a diagram illustrating an example when a still image is captured by driving the imaging unit 2 by the first driving method during live view.
When all the 1200 lines of pixel data illustrated in FIG. 6 are read out, it takes 60 ms, for example, but if only 200 lines of LV pixel data are read out, for example, about 17 ms ( More precisely, it can be read out in 16.67 ms, for example (see also FIG. 10 described later). In the former case, it is at most to read 16 still images per second, but in the latter case, image data of 60 frames per second can be acquired.
Accordingly, during live view, image data is acquired at, for example, 60 frames per second and displayed on the display unit 5 until the release button is pressed (here, the second step). At this time, as shown in the figure, when image data is acquired in a certain frame, the image data acquired in the next frame is displayed in live view.
When the release button is pressed during the live view, in the case shown in FIG. 7, that is, when the imaging unit 2 is driven by the first driving method to capture a still image. Then, the capturing of the live view image data is stopped, and the imaging operation as shown in FIG. 5 is performed. During the imaging operation, since live view image data is not acquired, a process of continuously displaying the last captured live view image data F as shown in FIG. 7 is performed. Note that instead of continuing to display the last captured live view image data F, the live view display may not be performed during the imaging operation.
Then, when the still image capturing operation as shown in FIG. 5 is completed, image data for live view is acquired again, and the image data acquired in the next frame is displayed in live view. In the example shown in FIG. 7, in order to reduce the period during which the live view is not performed even by one frame, it is acquired for the still image in the next frame after the still image capturing operation indicated by the thick solid line is completed. Live view image data α is generated from the image data to perform live view display.
Next, FIG. 8 is a diagram illustrating an example of capturing a still image by driving the imaging unit 2 by the second driving method during live view.
When the imaging unit 2 is driven by the first driving method as shown in FIG. 7, since the live view image is not acquired from when the release button is pressed until the imaging operation is completed, the display is performed. It will not be updated. On the other hand, when the imaging unit 2 is driven by the second driving method shown in FIG. 8, a live view image is acquired even after the release button is pressed until the imaging operation ends. The live view display is updated.
The operation shown in FIG. 8 is the same as that shown in FIG. 7 until the release button is pressed.
Then, when the release button is pressed, the reset data reading starts, but when the reset data of several lines is read, the live view image is acquired from the line from which the reset data has not yet been read. I do. The live view image is acquired one or more times until reading of the reset data is completed, and the reset data of each line used for acquiring the live view image is acquired at the end of the reset data reading period. In addition, when a live view image is acquired two or more times, the reset data is read between them. The live view image acquired during the reset data reading period in this way has a lower frame rate than the normal live view image, so the same live view image is displayed over a plurality of display frames. The display is updated and the display is updated when a new live view image is obtained.
Thereafter, the exposure period is started by resetting the photoelectric conversion unit PD, and the exposure period ends when the charge of the photoelectric conversion unit PD is transferred to the signal storage unit FD, which is the same as the operation shown in FIG.
Subsequently, a pixel data reading period is started. At this time, first, pixel data of each line used for acquiring a live view image is read, and thereafter pixel data of other lines is read. Do. Then, the live view image is acquired once or more at an appropriate time point (appropriate time point in the pixel data reading period) after the reading of the pixel data of each line used for acquiring the live view image is completed. At this time, when the live view image is acquired two or more times, the pixel data is read between them.
In the example shown in FIG. 8 as well, each line used for acquiring a live view image in order to reduce the period during which live view is not performed even by one frame, as in the example shown in FIG. In the next frame after the still image pixel data has been acquired, live view image data α is generated from the image data acquired for the still image to perform live view display.
Then, when the pixel data reading period ends, the normal live view is returned again in the same manner as in the example shown in FIG.
Next, FIG. 9 is a diagram illustrating another example when a still image is captured by driving the imaging unit 2 by the second driving method during live view.
The example shown in FIG. 9 is devised so as to further shorten the period during which the live view image is not acquired, compared to the example shown in FIG.
That is, in the example shown in FIG. 8, after the reset data reading is completed for all lines, the photoelectric conversion unit PD is reset and exposure is started. On the other hand, in the example shown in FIG. 9, after the acquisition of the last live view image in the reset data reading period, the photoelectric conversion unit PD is reset immediately, and after the exposure period is started, The remaining reset data is continuously read out. As can be seen by referring to the pixel configuration as shown in FIG. 3, when the transistor Mtx1 is turned off, the reset data can be read from the signal storage unit FD via the amplifying transistor Ma and the selection transistor Mb. This does not affect the accumulation of pixel charges in the photoelectric conversion unit PD that is started by turning off the signal. Therefore, it is possible to simultaneously perform exposure and readout of reset data in this way.
By performing such processing, it is possible to shorten the period during which the live view image cannot be acquired by the time t1 as shown in the figure as compared with the example shown in FIG. In addition, when such processing is performed, the time required from reading the reset data to reading the pixel data is shortened by time t1 as compared with the example shown in FIG. As shown in FIG. 4, the signal storage unit FD is directly connected to the wiring layer, and it is difficult to reduce the dark current. Therefore, shortening the time required from reading reset data to reading pixel data leads to a reduction in the amount of dark current generated, and it is possible to reduce the influence of reset data on pixel data. There is also an advantage of becoming.
Next, FIG. 10 is a timing chart showing the processing shown in FIG. 7 in more detail.
As described in FIG. 7, FIG. 10 also shows processing when the imaging unit 2 is driven by the first driving method to capture a still image during live view.
In the live view display period before the release button is turned on, for example, for the LV line shown in FIG. 6, the LV exposure start and the LV exposure end are performed for each display frame, and the next display frame is displayed. Is displayed.
When the release button is pressed, the reset data is read out, but the reset data for the still image is read out for all the lines of the pixel unit 24 (all 1200 lines in the example shown in FIG. 6). For this reason, the time required for reading the reset data is, for example, 60 ms as described above. Then, after the LV display of the LV image data (image data C in the illustrated example) acquired last before the reset data reading period is started, the period BL is entered. As described above, the period BL is a period in which the LV display is not performed (blackout) or the image data C is continuously displayed in the LV without being updated.
Then, after an exposure period (shutter speed Tex) and a pixel data readout period (for example, 60 ms as in the reset data readout period), acquisition of LV image data is started again, and the next after acquisition LV display is performed in the display frame. In the example shown in FIG. 10, the LV display is first updated after acquisition of the still image is the image data D. However, as described with reference to FIG. Based on the acquired image data, LV image data α may be generated and displayed in LV before the image data D.
Next, FIG. 11 is a timing chart showing an example of processing for acquiring LV image data only in the reset data reading period in the processing shown in FIG. That is, in the example shown in FIG. 11, unlike the example shown in FIG. 8, the acquisition of LV image data is not performed during the pixel data reading period.
In the example shown in FIG. 11, reading of reset data and acquisition of LV image data after the release button is pressed are performed based on the following principle.
First, as described above, each line used to acquire a live view image (hereinafter, referred to as an “LV line”. In addition, lines other than the LV line among all the lines are described below. The reset data of “non-LV line” is performed at the end of the reset data reading period.
Acquisition of LV image data is performed, for example, at a rate of once per a plurality of display frames (in the example shown in FIG. 11, LV image data C, D is acquired at a rate of once per two display frames. In this case, the LV image data B acquired last before the release button is pressed is displayed twice in LV, and similarly, the image data C is also displayed in LV twice. The LV image data D acquired last before resetting the part PD is displayed LV only once in the example shown in FIG. 11, but may be repeatedly displayed in the period BL as described above. Absent.). Note that acquisition of LV image data is not necessarily performed at a timing synchronized with a display frame.
Then, the period during which the LV image data is not acquired (in the example shown in FIG. 11, the period from when the release button is pressed until the reading of the LV image data C is started). In the period from the end of the reading to the start of reading out the LV image data D and the period after the end of reading out the LV image data D), the reset data of the non-LV line is read, for example, Do the numbers in ascending order.
Thereafter, as described above, the reset data of the LV line is read at the end of the reset data reading period.
Subsequently, the live view is started again after the exposure period and the pixel data reading period. In the example shown in FIG. 11, the live view is performed by the same LV line as before the release button is pressed.
In the example shown in FIG. 11 as well, live view display is performed by generating image data α for live view from image data acquired for still images in the next display frame after the still image capturing operation is completed. The period when the live view is not performed is reduced even by one frame.
Next, FIG. 12 is a timing chart showing a more detailed example of the process shown in FIG. In the example shown in FIG. 12, unlike the example shown in FIG. 11, LV image data is acquired in both the reset data reading period and the pixel data reading period.
Furthermore, in the example shown in FIG. 12, the LV line from which the LV image data is acquired before the exposure period is different from the LV line from which the LV image data is acquired after the exposure period (particularly, Different so that they do not overlap).
In the example shown in FIG. 12, reading of reset data and acquisition of LV image data after the release button is pressed is performed based on the following principle.
First, the reset data of the LV line after the exposure period is read out at the beginning of the reset data reading period (in the example shown in FIG. 12, the reading of the LV image data C is started after the release button is pressed. For the period).
In addition, acquisition of LV image data is performed at a rate of once per a plurality of display frames, for example. As described above, acquisition of LV image data does not necessarily have to be performed at a timing synchronized with a display frame.
A period during which the LV image data is not acquired (in the example shown in FIG. 12, a period from the end of reading the LV image data C to the start of reading out the LV image data D, and During the period after the end of reading of the LV image data D), the non-LV line (in the description of FIG. 12, the LV line before the exposure period and the LV line after the exposure period Lines that do not correspond to any of them are referred to as non-LV lines).
Thereafter, the reset data read from the LV line before the exposure period is read at the end of the reset data read period (in the example shown in FIG. 12, after the end of the reading of the LV image data D and the non-LV For a period after the completion of reading the reset data of the main line).
Subsequently, after an exposure period, a pixel data reading period is started. Then, first, in the example shown in FIG. 12, the pixel data of the LV line after the exposure period is read out after the exposure period ends until the reading of the LV image data E starts. . After this reading is completed, the LV image data can be read from the LV line after the exposure period even within the pixel data reading period.
Also in the example shown in FIG. 12, live view image data α is generated based on the pixel data read out for the still image from the LV line after the exposure period, and the live view display is performed in the immediately subsequent display frame. Is going.
Thereafter, the acquisition of the LV image data is performed at a rate of, for example, once for a plurality of display frames (the acquisition of the LV image data is not necessarily performed at a timing synchronized with the display frame, as described above. Is).
Next, a period during which the LV image data is not acquired (in the example shown in FIG. 12, a period from the end of reading out the LV image data E to the start of reading out the LV image data F, and In the period after the completion of the reading of the LV image data F), the reset data of the non-LV lines is read, for example, in ascending order of the line numbers.
Further, at the end of the pixel data reading period (in the example shown in FIG. 12, the period after the reading of the LV image data F is completed and after the reading of the reset data of the non-LV line is completed). In addition, the pixel data of the LV line before the exposure period is read out.
As a result, the imaging of the still image is completed, and thereafter normal live view display is performed.
In the example shown in FIG. 12, the time from the reset data read time to the pixel data read time is basically the same for each line (although some exceptions may occur depending on the timing). It is trying to become. This allows the amount of noise due to dark current to be the same for any line (with some exceptions as described above). Therefore, it is possible to prevent deterioration in image quality due to a difference in noise amount depending on the line.
In FIG. 12, LV image data is read in both the reset data reading period and the pixel data reading period, and in FIG. 11, LV image data is read only in one of the reset data reading periods. Further, it is of course possible to read out the LV image data only in the other pixel data reading period. That is, it is possible to read out the LV image data within at least one of the reset data reading period and the pixel data reading period.
In addition, when the processing shown in FIG. 12 is performed, an image displayed in live view is shifted up and down by several lines before and after the exposure period, but when the imaging apparatus is a digital camera or the like, Since the screen size of the display unit 5 is smaller than that of a display unit such as a personal computer, this shift is not so noticeable when displayed, and practical problems are hardly caused.
Next, FIG. 13 is a flowchart illustrating processing according to the shooting mode of the imaging apparatus.
For example, when the process is shifted to when the release button of the camera operation unit 11 is pressed, first, a photographing operation by the imaging device is started (step S1).
Subsequently, the camera control unit 12 determines whether the shooting mode is set to the single shooting mode or the continuous shooting mode (step S2).
If it is determined that the mode is the single shooting mode, the imaging unit 2 is driven by the first driving method (see FIG. 5, FIG. 7, FIG. 10, etc.) to capture a still image (step S3). This process ends.
If it is determined in step S2 that the continuous shooting mode is selected, the imaging unit 2 is driven by the second driving method (see FIGS. 8, 9, 11, 12, etc.) to display a still image. A picture is taken (step S4), and this process is terminated.
In the continuous shooting mode, it is desirable that AF data and AE data can be acquired and the photographer can check the subject in order to capture the next image even if one image has been captured. The LV image data is not only used for live view display on the display unit 5 but also used as AF data and AE data. Therefore, the second driving method is used during continuous shooting. Thus, the imaging unit 2 is driven. As a result, when continuous shooting is performed, the LV image is not updated or the time for blackout can be shortened. Even if the subject is a moving subject, the photographer places the subject within the shooting range. It is easy to change the shooting direction of the imaging device so as to be accommodated. Furthermore, each image captured during continuous shooting can be an image focused with higher accuracy based on AF tracking and an image with more appropriate exposure based on AE tracking. On the other hand, since it is sufficient to perform a normal AF operation or AE operation in the single shooting mode, the image pickup unit 2 is driven by the first driving method, and recording to the memory card 6 is performed after the release button is pressed. The time until completion is shortened.
Next, FIG. 14 is a flowchart illustrating processing according to the AF mode of the imaging apparatus.
Subsequently, the camera control unit 12 determines whether the AF mode is set to the single AF mode or the continuous AF mode (step S5).
Here, when it is determined that the single AF mode is selected, the imaging unit 2 is driven by the first driving method (see FIG. 5, FIG. 7, FIG. 10, etc.) to capture a still image (step S3). This process ends.
If it is determined in step S5 that the continuous AF mode is set, the imaging unit 2 is driven and stopped by the second driving method (see FIGS. 8, 9, 11, and 12). An image is taken (step S4), and this process ends.
In the continuous AF mode, it is desirable that AF data (if possible, AE data if possible) can be acquired immediately before the exposure period starts even after the release button is pressed halfway. Since the LV image data is used as AF data or AE data, the imaging unit 2 is driven by the second driving method in the continuous AF mode. As a result, an image shot in the continuous AF mode becomes an image shot with high AF tracking ability, and it is possible to focus with high accuracy even when shooting an object moving at high speed. On the other hand, in the single AF mode, since it is sufficient to perform a normal AF operation (and a normal AE operation), the image pickup unit 2 is driven by the first driving method, and the memory card 6 is pressed after the release button is pressed. The time until recording is completed is shortened.
In the above description, whether the imaging unit 2 is driven by the first driving method or the second driving method is selected according to the shooting mode or the AF mode. However, the selection is not limited to these, and the selection may be made according to other factors.
According to the first embodiment, when the LV image data is read by the second driving method in at least one of the reset data reading period and the pixel data reading period, the LV display is not displayed or updated. It is possible to shorten the period during which no operation is performed.
In addition, since the LV image data is acquired by the second driving method in the continuous shooting mode or the continuous AF mode, it is possible to ensure high AF tracking performance and high AE tracking performance. On the other hand, in the single shooting mode or the single AF mode, since the imaging unit 2 is driven by the first driving method, the time from when the release button is pressed until the recording to the memory card 6 is completed is shortened. It becomes possible to do.
At least during the period from when the release button is pressed until the reading of the pixel data is completed, the image formed on the image sensor is prevented from being blurred. Even when an image is formed as a luminance portion, it is possible to prevent an unnatural trajectory from being generated due to electric charge leaking into a light-shielded portion. Thereby, it is possible to acquire a natural image in which deterioration of image quality is prevented.
FIGS. 15 to 17 show Embodiment 2 of the present invention. FIG. 15 is a circuit diagram showing a configuration example of the pixel 28 in the pixel unit 24 of the image sensor 21, and FIG. FIG. 17 is a timing chart illustrating an operation when a still image is captured by a global shutter driven by a driving method. FIG. 17 illustrates a still image obtained by driving the imaging unit 2 by a second driving method during live view. It is a figure which shows the example when imaging.
In the second embodiment, parts that are the same as those in the first embodiment are given the same reference numerals and description thereof is omitted, and only differences are mainly described.
First, the configuration of the pixel 28 of the present embodiment will be described with reference to FIG. In FIG. 15, a pixel 28 surrounded by a dotted line indicates a pixel area for two pixels. That is, the image pickup device 21 shown in FIG. 15 has a configuration as shown in the drawing for every two adjacent pixels, for example.
The first photoelectric conversion unit PD positioned on the upper side of the drawing is connected to the transistor Mtx2 functioning as the first reset unit, and the second photoelectric conversion unit PD positioned on the lower side of the drawing is set to the transistor Mtx2 ′ functioning as the first reset unit. Are respectively connected to a signal line TX2 for applying a PD reset pulse. In the configuration shown in FIG. 15, the reset of the first photoelectric conversion unit PD is performed by the transistor Mtx2, and the reset of the second photoelectric conversion unit PD is performed by the transistor Mtx2 '.
The first photoelectric conversion unit PD is connected to a first charge storage unit C1 (which is a specific example of the first charge storage unit in the claims) via a transistor Mtx1 that functions as a gate unit. The second photoelectric conversion unit PD is a second charge storage unit C2 (a specific example of the first charge storage unit in the claims) via a transistor Mtx1 ′ functioning as a transfer unit and a gate unit. Connected to. The transistors Mtx1 and Mtx1 'are connected to a signal line TX1 for applying a transfer pulse.
The first charge storage unit C1 is connected to the signal storage unit FD (in this embodiment, a specific example of the second charge storage unit in the claims) via the transistor Mtx3 functioning as a gate unit. ing. Here, the transistor Mtx3 is connected to a signal line TX3 for applying a transfer pulse. The second charge storage unit C2 is connected to the signal storage unit FD via a transistor Mtx4 that functions as a gate unit. Here, the transistor Mtx4 is connected to a signal line TX4 for applying a transfer pulse.
The configuration after this signal storage unit FD is the same as that shown in FIG.
Next, with reference to FIG. 16, the imaging operation by the first driving method will be described. The image sensor 21 having the pixel configuration as shown in FIG. 15 is controlled to perform exposure first and then read out reset data and pixel data during the global shutter operation.
That is, when the release button of the camera operation unit 11 is pressed, the transistors Mtx2 and Mtx2 ′ of all the pixels of all the lines are simultaneously turned off via the signal line TX2, thereby charging the photoelectric conversion unit PD of all the pixels. Is started, that is, exposure of all pixels is started simultaneously (exposure period starts).
When a predetermined exposure period has elapsed after the start of exposure, a transfer pulse is simultaneously applied to the transistors Mtx1 and Mtx1 ′ of all the pixels of all lines via the signal line TX1, thereby accumulating in the photoelectric conversion unit PD. The pixel charges thus transferred are transferred to the first charge accumulation unit C1 and the second charge accumulation unit C2, that is, the exposure of all the pixels is completed simultaneously (end of the exposure period).
Subsequently, a readout period of reset data and pixel data is started.
That is, first, a reset pulse is applied from the signal line RES to the transistors Mr provided in common in the first row and the second row of the pixel portion 24, so that signals common to the first row and the second row are applied. The storage unit FD is reset. Further, the reset noise is read from the signal accumulation unit FD by applying a selection pulse from the signal line SEL to the selection transistors Mb provided in common in the first row and the second row of the pixel unit 24.
Immediately thereafter, by applying a transfer pulse to the transistor Mtx3 provided in the first row of the pixel portion 24 via the signal line TX3, the pixel charge accumulated in the first charge accumulation portion C1 is signal accumulated. Forward to the unit FD. Further, pixel data is read out from the signal accumulation unit FD by applying a selection pulse from the signal line SEL to the selection transistors Mb provided in common in the first row and the second row of the pixel unit 24.
Then, the CDS unit 25 performs a process of subtracting reset noise from the pixel data and outputs the result to the horizontal scanning circuit 27. Therefore, when the pixel configuration as shown in FIG. 15 is adopted, the KTC noise removing unit 23 in FIG. 2 is not necessarily required.
Such operations are sequentially performed from the first row to the n-th row (final row) for odd-numbered rows of the pixel unit 24, so that pixel data of odd-numbered lines from which reset noise has been removed is output. .
Next, the same operation is performed on even lines.
Immediately thereafter, by applying a transfer pulse to the transistor Mtx4 provided in the second row of the pixel portion 24 via the signal line TX4, the pixel charge accumulated in the second charge accumulation portion C2 is signal accumulated. Forward to the unit FD. Further, pixel data is read out from the signal accumulation unit FD by applying a selection pulse from the signal line SEL to the selection transistors Mb provided in common in the first row and the second row of the pixel unit 24.
Then, the CDS unit 25 performs a process of subtracting reset noise from the pixel data and outputs the result to the horizontal scanning circuit 27.
By sequentially performing such an operation from the second row to the n-th row (final row) for even-numbered rows of the pixel unit 24, pixel data of even-numbered lines from which reset noise has been removed is output. .
Then, at least from the start of the exposure period (at the start of resetting by the first reset unit) to the end of the pixel data reading period, camera shake correction by the camera shake correction unit 8 based on the detection result of the camera shake detection unit 7 is performed. ing.
Considering both the second embodiment and the first embodiment described above, the camera control unit 12 starts resetting by the first reset unit (at the start of the exposure period) and resetting by the second reset unit (reset). It can be said that at least the camera shake correction is controlled from the later of the data reading period) to the end of the pixel data reading period.
Next, with reference to FIG. 17, a process for capturing a still image by driving the imaging unit 2 by the second driving method during live view will be described.
In the present embodiment, when the release button is pressed during live view, the exposure period is started by resetting the photoelectric conversion units PD of all pixels, and the photoelectric conversion units PD of all pixels are started. Is transferred to the charge accumulating units C1 and C2 at the same time, thereby completing the exposure period.
Subsequently, as described above, the readout of the reset data and the readout of the pixel data are first performed on the LV line.
In the example shown in FIG. 17, live view image data α is generated based on the pixel data read out for the still image from the LV line, and live view display is performed in the immediately subsequent display frame.
Thereafter, the acquisition of the LV image data is performed at a rate of, for example, once for a plurality of display frames (however, as described above, the acquisition of the LV image data is performed on the display frame in the reset data and pixel data reading period) You don't have to do it at the same time).
Next, during the period when the LV image data is not acquired, the reset data and pixel data of the non-LV line are read in a predetermined order (for example, in order of increasing line number, the odd line is first, the even line is later). , Etc.).
When still image capturing is completed, normal live view display is performed thereafter.
In this embodiment, whether the imaging unit 2 is driven by the first driving method as shown in FIG. 16 or the imaging unit 2 is driven by the second driving method as shown in FIG. As in the above-described first embodiment, it is preferable to select according to the shooting mode, the AF mode, or other factors.
According to the second embodiment as described above, it is possible to obtain substantially the same effects as those of the first embodiment described above even in an image sensor having a pixel configuration as shown in FIG.
FIG. 18 to FIG. 21 show Embodiment 3 of the present invention, FIG. 18 is a diagram showing the configuration of the imaging unit 2, and FIG. 19 is a circuit that shows a configuration example of the pixel 28 in the pixel unit 24 of the imaging device 21. FIG. 20 is a timing chart showing a first operation example when the imaging unit 2 is driven by the second driving method to capture a still image by the global shutter. FIG. 21 is a timing chart showing the imaging unit 2 by the second driving method. 6 is a timing chart showing a second operation example when driving a still image to capture a still image using a global shutter.
In the third embodiment, parts that are the same as those in the first and second embodiments are given the same reference numerals, description thereof is omitted, and only differences are mainly described.
The imaging unit 2 of the present embodiment is configured to be able to read out pixel data and reset data from the pixel unit 24 from two output circuits, and is configured as a so-called multi-line readout imaging unit. It has become.
In other words, the pixel unit 24 in which the plurality of pixels 28 are arranged in a two-dimensional manner is applied with a signal in units of rows by a vertical control circuit 36 that also serves as a vertical scanning circuit, a reset control unit, and a signal readout control unit. The signals from the pixels in the selected row are output to the selected one of the vertical transfer lines VTL1 and VTL2 (see also FIG. 19) provided for each column.
All the vertical transfer lines VTL 1 configured in the pixel unit 24 are connected to the first output circuit 31. The first output circuit 31 includes, for example, a horizontal scanning circuit 27, an A / D conversion unit 22, and a KTC noise removal unit 23 in the configuration shown in FIG. 2 (however, further includes a CDS unit 25). It does not prevent it). The first output circuit 31 outputs a still image.
All the vertical transfer lines VTL <b> 2 configured in the pixel unit 24 are connected to the second output circuit 32. The second output circuit 32 includes, for example, the CDS unit 25, the horizontal scanning circuit 27, and the A / D conversion unit 22 in the configuration shown in FIG. 2 (however, further includes the KTC noise removal unit 23). It does not prevent it). The second output circuit 32 performs live view output.
Thus, the vertical control circuit 36 serves as both a live view data read control unit and a reset data / pixel data read control unit.
Next, a more detailed configuration of the pixel 28 will be described with reference to FIG.
First, as described above, the image sensor 21 of the present embodiment is provided with the vertical transfer line VTL1 and the vertical transfer line VTL2 in each column.
In the pixel 28 shown in FIG. 19, the configuration of the photoelectric conversion unit PD, the transistor Mtx2, the transistor Mtx1, the signal storage unit FD, the transistor Mr, and the amplification transistor Ma is the same as that of the pixel 28 shown in FIG.
However, the pixel 28 shown in FIG. 19 has a first selection transistor Mb1 (first signal charge readout unit, reset signal readout unit) and a second selection transistor Mb2 as signal charge readout units connected to the amplifying transistor Ma. (Second signal charge reading unit, third signal charge reading unit). The first selection transistor Mb1 is connected to the vertical transfer line VTL1 and to the signal line SEL1 for applying the first selection pulse. The second selection transistor Mb2 is connected to the vertical transfer line VTL2 and to the signal line SEL2 for applying the second selection pulse.
Accordingly, the charges accumulated in the signal accumulation unit FD are output to the vertical transfer line VTL1 by applying a selection pulse to the signal line SEL1, and are output to the vertical transfer line VTL2 by applying a selection pulse to the signal line SEL2. It has come to be. For two different lines, output to the vertical transfer line VTL1 and output to the vertical transfer line VTL2 can be performed simultaneously.
Next, a first operation example when the imaging unit 2 is driven by the second driving method to capture a still image using a global shutter will be described with reference to FIG. In FIG. 20 and the next FIG. 21, for the sake of simplicity, the total number of horizontal lines provided in the pixel unit 24 is 9 lines (in order of the lines L01 to L09 from the upper end side to the lower end side of the pixel unit 24). It is assumed that they are in line.
In the example shown in FIG. 20, the LV line is fixed to L03, L06, and L09. Accordingly, the non-LV lines are lines L01, L02, L04, L05, L07, and L08.
When the reset data reading period is started by pressing the release button, first, for the line L01, the transistor Mr is turned on to reset the signal storage unit FD, and the first selection transistor Mb1 is turned on to reset data. Is read. At the same time, for the line L03, the transistor Mr is turned on to reset the signal storage unit FD, the second selection transistor Mb2 is turned on to read the reset data, and the transistor Mtx1 is turned on to convert the pixel data into a photoelectric conversion unit. The data is transferred from the PD to the signal storage unit FD, and the second selection transistor Mb2 is turned on to read out pixel data.
Accordingly, by this operation, the first output circuit 31 outputs the still image reset data for the line L01 as the still image output, and the second output circuit 32 outputs the LV image data for the line L03 as the live view output. The Here, the reading of the LV image data from the line L03 is more specifically performed by successively reading the reset data and reading the pixel data, and the CDS unit 25 included in the second output circuit 32 performs the latter from the latter. Will be subtracted.
Subsequently, similar processing is performed to read out still image reset data from the line L02 and read out LV image data from the line L06.
Subsequently, similarly, the still image reset data is read from the line L04 (the line L03 is not yet read because the line L03 is an LV line), and the LV image data is read from the line L09.
Accordingly, since the LV image data A for one frame is output, the display unit 5 can perform live view display in the next display frame.
Similarly, the still image reset data is read from the line L05, the image data for LV is read from the line L03, the reset data for still image is read from the line L07, the image data for LV is read from the line L06, and the line L08 is read. The image data B for LV for the next one frame is output by reading the reset data for still image from LV and the image data for LV from line L09.
Since reading of the still image reset data for the non-LV line is completed at this point, reading of the still image reset data for the LV line is started next. Therefore, after this time point, the live view display is not updated or enters the blackout period BL until the exposure period ends and the LV image data can be acquired from the LV line in the pixel data reading period. (However, the period BL shown in FIG. 20 is displayed on the time chart of the live view output, but the actual LV display is performed in the next display frame from which the LV image data is acquired. This means that it is shifted by about one display frame from the display period BL in the display unit 5. The same applies to the following description.) That is, at the end of the reset data reading period, still image reset data is read from line L03, still image reset data is read from line L06, and still image reset data is read from line L09.
After that, by simultaneously turning off the transistors Mtx2 of all the pixels in all the lines via the signal line TX2, exposure of all the pixels is started simultaneously.
When a predetermined exposure period has elapsed, a transfer pulse is simultaneously applied to the transistors Mtx1 of all the pixels of all lines via the signal line TX1, thereby transferring the pixel charges to the signal storage unit FD and exposing all the pixels. At the same time.
Subsequently, a pixel data reading period is started.
Then, in order to make it possible to acquire LV image data from the LV line at the earliest possible time, first, reading of still image pixel data of the LV line is started. That is, at the beginning of this pixel data reading period, still image pixel data is read from line L03, still image pixel data is read from line L06, and still image pixel data is read from line L09. Therefore, the period BL ends when the reading is completed, and LV image data can be acquired after this point.
In the present embodiment, since it is assumed that the output image is different between the still image and the live view image, in the flow shown in FIG. 20, the LV line is displayed at the beginning of the pixel data reading period. The image data α for live view is not generated based on the still image pixel data read out from the image data, but the image data α is generated so that live view display is performed from the point earlier by one display frame. It doesn't matter.
Next, the still image pixel data is read from the line L01, the LV image data is read from the line L03, the still image pixel data is read from the line L02, the LV image data is read from the line L06, and the line L04 is read. The LV image data C for one frame is output by reading out the still image pixel data and the LV image data from the lines L09.
Similarly, still image pixel data is read from line L05, image data for LV is read from line L03, still image pixel data is read from line L07, and image data for LV is read from line L06, and line L08 is read. The image data D for LV for the next one frame is output by reading the pixel data for still image from LV and the image data for LV from line L09.
Since the readout of the still image pixel data of all lines is completed at this time, the still image has been captured, and normal live view display is performed after this time.
Next, a second operation example when the imaging unit 2 is driven by the second driving method and a still image is captured by the global shutter will be described with reference to FIG.
In the first embodiment described above, as described with reference to FIGS. 11 and 12, if the time from the reset data read time to the pixel data read time differs for each line, the amount of noise caused by dark current Will be different for each line. This also applies to the processing flow as shown in FIG. Therefore, the processing flow shown in FIG. 21 is such that the processing flow shown in FIG. 20 is changed so that the noise amount of each line is basically constant.
That is, in the example shown in FIG. 21, unlike the example shown in FIG. 20, the LV line (lines L03, L06, L09) from which the LV image data is acquired before the exposure period and the LV after the exposure period. The LV lines (lines L01, L04, L07) from which the image data is acquired are differentiated so as not to overlap. Here, the LV line before the exposure period and the LV line after the exposure period are lines selected at a constant line interval so as to cover the entire surface of the pixel portion 24 as evenly as possible.
When the reset data reading period is started by pressing the release button, first, the reset data of the LV line after the exposure period is read. Specifically, the still image reset data is read from the line L01, the image data for LV is read from the line L03, the reset data for still image is read from the line L04, the image data for LV is read from the line L06, and the still image is read from the line L07. By reading out the image reset data and the LV image data from the lines L09 to LV, the LV line reset data after the exposure period is output and the LV image data A for one frame is output.
Subsequently, the still image reset data is read from the line L02, the image data for LV is read from the line L03, the reset data for still image is read from the line L05, the image data for LV is read from the line L06, and the image data is read from the line L08. By reading the still image reset data and the LV image data from the lines L09, the reset data and the LV image data B for the next one frame are output.
Then, at the end of the reset data reading period, still image reset data is read from line L03, still image reset data is read from line L06, and still image reset data is read from line L09.
The processing in the subsequent exposure period is the same as the processing shown in FIG.
When the exposure period ends, a pixel data read period starts next.
Then, first, the still image pixel data of the LV lines (lines L01, L04, and L07) after the exposure period in which the reset data is first read out in the reset data reading period is sequentially read. From this point on, it is possible to acquire LV image data from the LV line after the exposure period.
Also in the flow shown in FIG. 21, live view image data α is generated based on still image pixel data read from the LV line at the beginning of the pixel data read period, and from one point earlier by one display frame. Live view display may be used.
Next, the still image pixel data is read from the line L02, the image data for LV is read from the line L01, the still image pixel data is read from the line L05, the image data for LV is read from the line L04, and the line L08 is read. The LV image data C for one frame is output by reading the still image pixel data and the LV image data from the lines L07.
Similarly, the still image pixel data is read from the line L03, the image data for LV is read from the line L01, the pixel data for still image is read from the line L06, the image data for LV is read from the line L04, and the line L09 is read. The image data D for LV for the next one frame is output by reading out the pixel data for still image from LV and the image data for LV from line L07.
As can be seen with reference to FIG. 21, the process as shown in FIG. 21 is performed by dividing the pixel unit 24 into a plurality of fields (line groups or pixel groups) and reading out at a certain time. It can be seen that, for example, one of the plurality of fields is used for LV reading. That is, in the reset data reading period before exposure, when reset data of another field is read, the last read field is used to read LV pixel data. In the pixel data read period after exposure, when pixel data of another field is read, the first read field is used to read LV pixel data.
If the processing as shown in FIG. 21 is performed, it is possible to prevent deterioration in image quality due to a difference in noise amount depending on the line.
In this embodiment, since the still image is read from one output system for multi-line readout and the live view image is read from the other output system, simultaneous readout is possible if the lines are different. The reset data reading period and the pixel data reading period do not become longer than in the first driving method of the first embodiment. Therefore, it is not necessary to select the first driving method and the second driving method according to the shooting mode or the AF mode.
However, when the first output circuit 31 and the second output circuit 32 have the same configuration (that is, as described above, the first output circuit 31 includes the CDS section 25 and the second output circuit 32 includes the KTC). In the case of including the noise removal unit 23, it is possible to perform either live view output from the first output circuit 31 or still image output from the second output circuit 32. is there. Therefore, in this embodiment, when outputting for a still image by the first driving method, it is possible to perform two-line readout from the first output circuit 31 and the second output circuit 32, thereby speeding up the readout. be able to. Therefore, when reading by the first driving method is two-line reading, it is effective to select the first driving method and the second driving method according to the photographing mode or the AF mode.
In the above description, two-line readout is given as an example of multi-line readout. Of course, 3-line readout or more multi-line readout may be used.
According to the third embodiment, in the configuration including the multi-line readout imaging unit, it is possible to achieve substantially the same effect as the first embodiment described above. Furthermore, since multi-line readout is employed, the readout period (reset data readout period and / or pixel data readout period) can be shortened as compared with the first embodiment. Unlike the first embodiment, the acquisition of LV image data in the reset data reading period and the pixel data reading period can be performed once per display frame.
22 and FIG. 23 show Embodiment 4 of the present invention. FIG. 22 is a circuit diagram showing a configuration example of the pixel 28 in the pixel portion 24 of the image sensor 21, and FIG. It is a figure which shows the example when driving the image pick-up part 2 by the 2nd drive method inside, and imaging a still image.
In the fourth embodiment, the same parts as those in the first to third embodiments are denoted by the same reference numerals, description thereof is omitted, and only different points will be mainly described.
First, the configuration of the pixel 28 will be described with reference to FIG. The pixel 28 of this embodiment is obtained by changing the pixel 28 as shown in the second embodiment to multi-line readout (specifically, two-line readout). Therefore, the configuration of the imaging unit 2 is the same as that shown in FIG. Also in FIG. 22, the pixel 28 surrounded by a dotted line indicates a pixel area for two pixels.
In the pixel 28 shown in FIG. 22, the photoelectric conversion unit PD, the transistors Mtx2 and Mtx2 ′, the transistors Mtx1 and Mtx1 ′, the charge storage units C1 and C2, the transistors Mtx3 and Mtx4, the signal storage unit FD, the transistor Mr, and the amplification transistor The configuration of Ma is the same as that of the pixel 28 shown in FIG.
However, the pixel 28 shown in FIG. 22 has two signal charge reading sections connected to the amplifying transistor Ma: a first selection transistor Mb1 and a second selection transistor Mb2. The first selection transistor Mb1 is connected to the vertical transfer line VTL1 and to the signal line SEL1 for applying the first selection pulse. The second selection transistor Mb2 is connected to the vertical transfer line VTL2 and to the signal line SEL2 for applying the second selection pulse.
Accordingly, the charges accumulated in the signal accumulation unit FD are output to the vertical transfer line VTL1 by applying a selection pulse to the signal line SEL1, and are output to the vertical transfer line VTL2 by applying a selection pulse to the signal line SEL2. It has come to be. Then, as shown in FIG. 22, two continuous lines having a common signal accumulation unit FD are one readout group (line m and line (m + 1) are one readout group when m is an integer. , When the lines 1 and 2 are the first readout group, the lines 3 and 4 are the second readout group,...), The two lines with different readout groups are transferred to the vertical transfer line VTL1. And the output to the vertical transfer line VTL2 can be performed simultaneously.
Next, with reference to FIG. 23, a process for capturing a still image by driving the imaging unit 2 by the second driving method during live view will be described.
When the release button is pressed during live view, first, the exposure period is started by resetting the photoelectric conversion parts PD of all the pixels, and the charge of the photoelectric conversion parts PD of all the pixels is transferred to the charge storage part. The exposure period is completed by transferring all the data to C1 and C2.
Subsequently, the reset data reading and the pixel data reading are successively performed for the LV line.
Thereafter, the reset data reading and the pixel data reading are continuously performed for the LV line, and the reset data reading and the pixel data reading are continuously performed for the non-LV line at the same time. Do it in parallel.
At this time, even if a certain LV line and a read group are the same non-LV line, when reading LV pixel data from another LV line, they can be read in parallel at the same time. A specific example will be described with reference to FIG. 6 of the first embodiment described above. When the LV pixel data is read from the LV line 6 of the third readout group consisting of the lines 5 and 6, the lines 11 and 12 are read out. It is possible to simultaneously read out the pixel data for still images from the non-LV line 12 of the sixth readout group.
Note that, in the present embodiment, similarly to the above-described third embodiment, since the output system is different between the still image and the live view image, the pixel data read in the flow shown in FIG. The live view image data α is not generated based on the still image pixel data read from the LV line at the beginning of the period. However, it is of course possible to generate the image data α and perform live view display from a point earlier by one display frame.
In this embodiment as well, as in each of the above-described embodiments, whether the imaging unit 2 is driven by the first driving method or the imaging unit 2 is driven by the second driving method is determined according to the shooting mode or You may select according to AF mode or other factors.
Also in this embodiment, two-line readout is given as an example of multi-line readout, but of course, multi-line readout with three or more lines may be used.
According to the fourth embodiment, in the configuration including the multi-line readout type imaging unit, it is possible to achieve substantially the same effect as the second embodiment described above. Furthermore, since multi-line readout is employed, the readout period (reset data and pixel data readout period) can be shortened as compared with the second embodiment. Unlike the second embodiment, the LV image data can be acquired once per display frame in the reset data and pixel data readout period.
In each of the above-described embodiments, the imaging device is mainly described. However, the present invention is not limited to the imaging device. For example, the live view image and the still image are described above in the imaging device. The image capturing method may be an image capturing method of the image capturing apparatus, or an image capturing process program of the image capturing apparatus, a recording medium that records the image capturing process program of the image capturing apparatus, or the like.
Further, the present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the constituent elements without departing from the scope in the implementation stage. Moreover, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, you may delete some components from all the components shown by embodiment. Furthermore, the constituent elements over different embodiments may be appropriately combined. Thus, it goes without saying that various modifications and applications are possible without departing from the spirit of the invention.
1. Lens (photographing lens)
2 ... Imaging unit 3 ... Image processing unit 3a ... First image processing unit 3b ... Second image processing unit (also serves as third image processing unit)
4 ... AF evaluation value calculation unit 5 ... Display unit 6 ... Memory card 7 ... Camera shake detection unit 8 ... Camera shake correction unit (shake correction unit)
DESCRIPTION OF SYMBOLS 9 ... Exposure control part 10 ... AF control part 11 ... Camera operation part 12 ... Camera control part 21 ... Image pick-up element 22 ... A / D conversion part 23 ... KTC noise removal part 24 ... Pixel part 25 ... CDS part 26 ... Vertical control circuit DESCRIPTION OF SYMBOLS 27 ... Horizontal scanning circuit 28 ... Pixel 31 ... 1st output circuit 32 ... 2nd output circuit 36 ... Vertical control circuit PD ... Photoelectric conversion part FD ... Signal storage part (Storage part, 1st charge storage part, 2nd charge storage part) )
C1... Charge storage unit (first charge storage unit)
C2: Charge storage unit (first charge storage unit)
Ma ... amplifying transistor Mb ... selection transistor (first signal charge reading unit, second signal charge reading unit, reset signal reading unit, third signal charge reading unit)
Mb1... Selection transistor (first signal charge reading unit, reset signal reading unit)
Mb2... Selection transistor (second signal charge reading unit, third signal charge reading unit)
Mr: Transistor (second reset unit)
Mtx1, Mtx1 ′... Transistor (transfer unit, gate unit)
Mtx2, Mtx2 ′... Transistor (first reset unit)
Mtx3 ... Transistor (gate part)
Mtx4 ... Transistor (gate part)
A pixel unit in which pixels including a photoelectric conversion unit that generates a signal charge according to an exposure amount are two-dimensionally arranged;
A reset unit that collectively resets the photoelectric conversion unit;
An exposure control unit that controls the photoelectric conversion unit to be exposed for a predetermined time from the reset by the reset unit;
The signal charges generated by the photoelectric conversion unit are collectively transferred and accumulated, and the light-shielded first charge accumulation unit,
A signal charge of a predetermined pixel group out of signal charges stored in the first charge storage section is read out before a signal charge of another pixel group, and then a signal charge of the other pixel group is read out first. A signal charge readout unit;
A first image processing unit that generates first image data for still image recording based on the signal charge read by the first signal charge reading unit;
A second signal charge reading unit that reads the signal charge generated by the predetermined pixel group one or more times within a time interval in which the signal charge of the other pixel group is read by the first signal charge reading unit;
A second image processing unit for generating second image data for image display based on the signal charge read by the second signal charge reading unit;
A camera control unit for controlling whether the first image data for still image recording is acquired by single shooting or continuous shooting;
When acquiring by single shooting, the second signal charge reading unit and the second image processing unit are not operated. When acquiring by continuous shooting, the second signal charge reading unit and the second image are acquired. An image pickup apparatus that performs an operation of a processing unit .
The photoelectric conversion unit;
A first transistor functioning as the reset unit;
A second transistor for transferring the charge generated by the photoelectric conversion unit to the first charge storage unit;
Transferring and accumulating charges accumulated in the first charge accumulating portion, and shielding the second charge accumulating portion;
A third transistor for transferring the charge accumulated in the first charge accumulation unit to the second charge accumulation unit;
A fourth transistor for resetting the second charge storage unit;
A fifth transistor for amplifying the voltage of the second charge storage unit;
A sixth transistor for selecting an output signal of the fifth transistor;
The imaging apparatus further includes a reset signal reading unit that reads a voltage of the second charge storage unit when the second charge storage unit is reset by the fourth transistor as a reset signal after exposing the photoelectric conversion unit. And
The first image processing unit converts the first image data based on a difference between the signal charge read by the first signal charge reading unit and the reset signal read by the reset signal reading unit. The imaging device according to claim 1, wherein the imaging device is generated.
A third transistor for resetting the first charge storage unit;
A fourth transistor for amplifying the voltage of the first charge storage unit;
A fifth transistor for selecting an output signal of the fourth transistor;
The imaging apparatus further includes a reset signal reading unit that reads a voltage of the first charge storage unit when the first charge storage unit is reset by the third transistor as a reset signal before exposing the photoelectric conversion unit. And
The pixel includes the photoelectric conversion unit, a first transistor functioning as the reset unit, a second transistor for transferring charges generated by the photoelectric conversion unit to the first charge storage unit, and the first transistor Transferring and accumulating charges accumulated in the charge accumulating unit for transferring the light-shielded second charge accumulating unit and charges accumulated in the first charge accumulating unit to the second charge accumulating unit A third transistor, a fourth transistor for resetting the second charge storage unit, a fifth transistor for amplifying the voltage of the second charge storage unit, and an output signal of the fifth transistor A sixth transistor for
The first image processing unit converts the first image data based on a difference between the signal charge read by the first signal charge reading unit and the reset signal read by the reset signal reading unit. Generate
At least from the time of batch reset of the photoelectric conversion unit by the first transistor to the end of reading of the signal charge by the first signal charge reading unit, the blur correction that reduces the blur of the optical image exposed to the pixel unit part you wherein, further provided with the imaging device.
The pixel includes the photoelectric conversion unit, a first transistor functioning as the reset unit, a second transistor for transferring charges generated by the photoelectric conversion unit to the first charge storage unit, and the first transistor A third transistor for resetting the charge storage unit; a fourth transistor for amplifying the voltage of the first charge storage unit; a fifth transistor for selecting an output signal of the fourth transistor;
At least from the start of resetting of the first charge storage unit by the third transistor to the end of reading of the signal charge by the first signal charge reading unit, blurring of the optical image exposed to the pixel unit is reduced. imaging device characterized by comprising shake correction unit further.
An AF control unit for performing autofocus control on the photographing lens;
A camera control unit for controlling the AF control unit by single AF or continuous AF when acquiring the first image data for still image recording;
When controlling by single AF, the second signal charge reading unit and the second image processing unit are not operated. When controlling by continuous AF, the second signal charge reading unit and the second image processing unit are not operated. you and performs operation of the second image processing section imaging device.
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