Patent Description:
With an imaging device such as a digital single-lens camera or a compact digital camera, for example, a user checks an image displayed on a display unit such as an LCD or an electric viewfinder (EVF), determines an image capturing timing, and captures an image by pressing a release button (shutter button). The image displayed on the display unit at this time is called a live view image, a through image, or the like. There may be a case where a phenomenon of what is called a blackout occurs in the imaging device, in which a live view image is not displayed on the display unit due to exposure preparation processing starting by the release button being pressed.

In order to avoid an occurrence of a blackout, for example, there is a configuration in which an image for display stored in a frame memory is displayed on a display unit until display of an image for recording is enabled (refer to Patent Document <NUM>, for example).

Although the occurrence of the blackout can be avoided by increasing image read-out speed, a circuit for high-speed read-out increases in scale and power consumption also increases.

The present technology has been developed to solve such a problem mentioned above and to enable avoidance of an occurrence of a blackout by using low-speed read-out.

A mode for carrying out the present technology (hereinafter, referred to as an embodiment) will be described below. Note that the description will be made in the following order.

<FIG> is a block diagram illustrating an embodiment of an imaging device including a solid-state imaging device to which the present technology is applied.

An imaging device <NUM> in <FIG> includes, for example, a digital single-lens camera, a compact digital camera, or the like, captures an image of a subject to generate the captured image, and records the captured image as a still image or a moving image. Hereinafter, it is assumed that a still image is mainly recorded.

The imaging device <NUM> includes a lens unit <NUM>, an operation unit <NUM>, a control unit <NUM>, a solid-state imaging device <NUM>, a signal processing unit <NUM>, a recording unit <NUM>, a display unit <NUM>, an AF control unit <NUM>, and a drive unit <NUM>.

The lens unit <NUM> collects light from the subject (subject light). The subject light collected by the lens unit <NUM> is incident on the solid-state imaging device <NUM>.

The lens unit <NUM> includes a zoom lens <NUM>, a diaphragm <NUM>, and a focus lens <NUM>.

The zoom lens <NUM> moves in an optical axis direction by being driven by the drive unit <NUM> to vary a focal length and adjust a magnification of the subject included in the captured image. The diaphragm <NUM> changes a degree of aperture by being driven by the drive unit <NUM> to adjust an amount of subject light incident on the solid-state imaging device <NUM>. The focus lens <NUM> moves in the optical axis direction by being driven by the drive unit <NUM> to adjust focus. Note that the zoom lens <NUM> may be omitted.

The operation unit <NUM> receives operation by a user. The user performs, for example, operation of changing an imaging mode, pressing a release button (not illustrated), or the like with the operation unit <NUM>. For example, in a case where the release button is pressed, the operation unit <NUM> supplies the control unit <NUM> with an operation signal indicating that the release button has been pressed.

The control unit <NUM> controls operation of each of the units of the imaging device <NUM>.

For example, in a case where the control unit <NUM> receives an operation signal indicating that the release button has been pressed, the control unit supplies the signal processing unit <NUM> with an instruction to record a still image. Furthermore, in a case where a live view image, which is a real-time image of a subject, is to be displayed on the display unit <NUM>, the control unit <NUM> supplies the signal processing unit <NUM> with an instruction to generate the live view image.

Furthermore, in a case where in-focus judgment is to be performed, the control unit <NUM> supplies the signal processing unit <NUM> with an instruction to operate the in-focus judgment. Although examples of the focus control method include a contrast method, a phase-difference detection method, and the like, the focus control method is not limited.

The solid-state imaging device <NUM> photoelectrically converts received subject light and outputs the subject light as an electric signal. The solid-state imaging device <NUM> is implemented by, for example, a complementary metal oxide semiconductor (CMOS) image sensor. The solid-state imaging device <NUM> has a pixel array unit in which a plurality of pixels is two-dimensionally arranged in a matrix, and supplies the signal processing unit <NUM> with pixel signals obtained as a result of receiving light in the respective pixels. Details of the solid-state imaging device <NUM> will be described later with reference to <FIG> and subsequent drawings.

The signal processing unit <NUM> performs various types of signal processing on a pixel signal supplied from the solid-state imaging device <NUM>. For example, in a case where an instruction to record a still image is supplied from the control unit <NUM>, the signal processing unit <NUM> generates, on the basis of the pixel signal from the solid-state imaging device <NUM>, data of a still image (still image data) as an image for recording, and supplies the data to the recording unit <NUM>. Furthermore, in a case where an instruction to generate a live view image, which is an image for display, is supplied from the control unit <NUM>, the signal processing unit <NUM> generates, on the basis of the pixel signal from the solid-state imaging device <NUM>, data of a live view image (live view image data), and supplies the data to the display unit <NUM>. The signal processing unit <NUM> can perform predetermined image processing such as, for example, demosaic processing, shading correction, or color mixture correction, as necessary.

Furthermore, the signal processing unit <NUM> generates a signal for focus control on the basis of a pixel signal supplied from the solid-state imaging device <NUM>, and supplies the generated signal to the AF control unit <NUM>.

The recording unit <NUM> records (stores) the image data of the image for recording (still image) supplied from the signal processing unit <NUM>. The recording unit <NUM> includes, for example, one or a plurality of removable recording media, such as a disk such as a digital versatile disc (DVD), or a semiconductor memory such as a memory card. These recording media may be incorporated in the imaging device <NUM> or may be detachable from the imaging device <NUM>.

The display unit <NUM> displays an image on the basis of the image data of the image for display supplied from the signal processing unit <NUM>. The display unit <NUM> displays, for example, a live view image, a still image read from the recording unit <NUM>, or the like. The display unit <NUM> is implemented by, for example, a liquid crystal display (LCD), an organic electro-luminescence (EL) display, an electric viewfinder (EVF), or the like.

The AF control unit <NUM> calculates a focus shift amount (defocus amount) on the basis of the signal for focus control supplied from the signal processing unit <NUM>, and judges whether or not an object to be focused (focus target object) is in focus. In a case where an object in a focus area is in focus, the AF control unit <NUM> supplies the drive unit <NUM> with information indicating the in-focus state as an in-focus judgment result. Furthermore, in a case where the focus target object is out of focus, the AF control unit <NUM> supplies the drive unit <NUM> with information indicating the calculated defocus amount as an in-focus judgment result.

The drive unit <NUM> drives the zoom lens <NUM>, the diaphragm <NUM>, and the focus lens <NUM>. For example, the drive unit <NUM> calculates a drive amount of the focus lens <NUM> on the basis of the in-focus judgment result supplied from the AF control unit <NUM>, and causes the focus lens <NUM> to move according to the calculated drive amount.

Specifically, in a case where focus is achieved, the drive unit <NUM> maintains a current position of the focus lens <NUM>. Furthermore, in a case where focus is not achieved, the drive unit <NUM> calculates a drive amount (moving distance) on the basis of the in-focus judgment result indicating the defocus amount and the position of the focus lens <NUM>, and causes the focus lens <NUM> to move according to the drive amount.

In the imaging device <NUM> configured as described above, the user checks an image displayed on the display unit <NUM>, determines an image capturing timing, and presses the release button (shutter button) to capture an image. At this time, a live view image, which is an image for checking, is displayed on the display unit <NUM>, and image data of the still image as the image for recording is recorded in the recording unit <NUM> at the timing of pressing the release button.

The solid-state imaging device <NUM> of the imaging device <NUM> can perform driving that achieves blackout free not only until the user checks the live view image displayed on the display unit <NUM> and confirms a release timing, but also after the user presses the release button. Here, the blackout refers to a phenomenon in which a live view image is not displayed on the display unit <NUM>, and the blackout free refers to a state where no blackout occurs.

Hereinafter, details of the solid-state imaging device <NUM> will be described.

<FIG> is a block diagram illustrating a schematic configuration of the solid-state imaging device <NUM>.

The solid-state imaging device <NUM> in <FIG> has a pixel array unit <NUM> in which pixels <NUM> are two-dimensionally arranged in a matrix on a semiconductor substrate using, for example, silicon (Si) as a semiconductor, and a peripheral circuit unit around the pixel array unit <NUM>. The peripheral circuit unit includes a vertical drive circuit <NUM>, column signal processing circuits <NUM>, a horizontal drive circuit <NUM>, an output circuit <NUM>, a control circuit <NUM>, or the like.

In the pixel array unit <NUM>, for example, pixels <NUM> on which red, green, and blue color filters are arranged in a Bayer pattern are two-dimensionally arranged in a matrix. A pixel <NUM> has a photodiode as a photoelectric conversion unit and a plurality of pixel transistors. The plurality of pixel transistors includes, for example, four MOS transistors, which are a transfer transistor, a selection transistor, a reset transistor, and an amplification transistor.

Furthermore, the pixel <NUM> may have a shared pixel structure. This shared pixel structure includes a plurality of photodiodes, a plurality of transfer transistors, one shared floating diffusion (floating diffusion region), and another each one of shared pixel transistors. That is, in the shared pixel structure, photodiodes and transfer transistors that constitute a plurality of unit pixels are configured to share another each one of pixel transistors.

The vertical drive circuit <NUM> includes, for example, a shift register or an address decoder, selects a predetermined pixel drive wiring <NUM>, supplies the selected pixel drive wiring <NUM> with a pulse for driving the pixels <NUM>, and drives the pixels <NUM> row by row. That is, the vertical drive circuit <NUM> sequentially selects and scans each of the pixels <NUM> of the pixel array unit <NUM> in a vertical direction row by row, and supplies a column signal processing circuit <NUM> via a vertical signal line <NUM> with a pixel signal based on a signal charge generated according to an amount of received light in the photoelectric conversion unit of each of the pixels <NUM>. Note that, although each of the pixel drive wiring <NUM> is illustrated with a single line in <FIG>, the pixel drive wiring <NUM> actually includes a plurality of lines.

A column signal processing circuit <NUM> is arranged for each column of the pixels <NUM>, and performs signal processing such as noise removal on signals output from the pixels <NUM> of one row with respect to each pixel column. For example, the column signal processing circuit <NUM> performs signal processing such as correlated double sampling (CDS) for removing pixel-specific fixed pattern noise, or AD conversion.

The horizontal drive circuit <NUM> includes, for example, a shift register, selects each of the column signal processing circuits <NUM> in order by sequentially outputting horizontal scanning pulses, and causes each of the column signal processing circuits <NUM> to output a pixel signal to a horizontal signal line <NUM>.

The output circuit <NUM> performs predetermined signal processing on the signals sequentially supplied from each of the column signal processing circuits <NUM> through the horizontal signal line <NUM>, and outputs the processed signals. For example, the output circuit <NUM> may perform only buffering or may perform various types of digital signal processing such as black level adjustment or column variation correction.

The control circuit <NUM> receives an input clock and data that orders an operation mode or the like, and outputs data such as internal information about the solid-state imaging device <NUM>. That is, the control circuit <NUM> generates a clock signal or a control signal serving as a reference of operation of the vertical drive circuit <NUM>, the column signal processing circuit <NUM>, the horizontal drive circuit <NUM>, or the like, on the basis of a vertical synchronization signal, a horizontal synchronization signal, and a master clock. Then, the control circuit <NUM> outputs the generated clock signal and control signal to the vertical drive circuit <NUM>, the column signal processing circuits <NUM>, the horizontal drive circuit <NUM>, or the like. An input/output terminal <NUM> includes, for example, a solder ball or the like, and exchanges signals with an outside.

The solid-state imaging device <NUM> configured as described above is a CMOS image sensor called a column AD method in which the column signal processing circuits <NUM> that perform CDS processing and AD conversion processing are arranged with respect to each pixel column.

<FIG> illustrates an equivalent circuit of a pixel <NUM>.

The pixel <NUM> has a photodiode <NUM>, a first transfer transistor <NUM>, a memory unit (MEM) <NUM>, a second transfer transistor <NUM>, a floating diffusion (FD) <NUM>, a reset transistor <NUM>, an amplification transistor <NUM>, a selection transistor <NUM>, and a discharge transistor <NUM>.

The photodiode <NUM> is a photoelectric conversion unit that receives and photoelectrically converts incident light to generate and accumulate an electric charge (signal charge). An anode terminal of the photodiode <NUM> is grounded, and a cathode terminal of the photodiode <NUM> is connected to the memory unit <NUM> via the first transfer transistor <NUM>. Furthermore, the cathode terminal of the photodiode <NUM> is also connected to the discharge transistor <NUM>.

When turned on by a transfer signal TRX, the first transfer transistor <NUM> reads an electric charge generated by the photodiode <NUM> and transfers the electric charge to the memory unit <NUM>. The memory unit <NUM> is a charge holding unit that temporarily holds an electric charge until a read-out timing comes and the electric charge is transferred to the FD <NUM>. When turned on by a transfer signal TRG, the second transfer transistor <NUM> transfers the electric charge held in the memory unit <NUM> to the FD <NUM>.

The FD <NUM> is a charge holding unit that holds the electric charge read from the memory unit <NUM> in order to read the electric charge as a signal. When the reset transistor <NUM> is turned on by a reset signal RST, the electric charge held in the FD <NUM> is discharged to a constant voltage source VDD to reset an electric potential of the FD <NUM>.

The amplification transistor <NUM> outputs a pixel signal corresponding to an electric potential of the FD <NUM>. That is, along with a load MOS <NUM> as a constant current source, the amplification transistor <NUM> constitutes a source follower circuit, and a pixel signal indicating a level corresponding to the electric charge held in the FD <NUM> is output from the amplification transistor <NUM> to a column signal processing circuit <NUM> (<FIG>) via the selection transistor <NUM>. The load MOS <NUM> is provided in the column signal processing circuit <NUM>, for example.

The selection transistor <NUM> is turned on when the pixel <NUM> is selected by a selection signal SEL, and outputs a pixel signal of the pixel <NUM> to the column signal processing circuit <NUM> via the vertical signal line <NUM>. When turned on by a discharge signal OFG, the discharge transistor <NUM> discharges unnecessary electric charge accumulated in the photodiode <NUM> to the constant voltage source VDD. The transfer signals TRX and TRG, the reset signal RST, the selection signal SEL, and the discharge signal OFG are controlled by the vertical drive circuit <NUM> and supplied via the pixel drive wiring <NUM> (<FIG>).

The pixel <NUM> has a pixel circuit as described above, and the solid-state imaging device <NUM> can capture an image with the global shutter method.

<FIG> is a conceptual diagram illustrating imaging methods, which are the global shutter method and a rolling shutter method.

As illustrated on a left side in <FIG>, the rolling shutter method is a method for executing exposure start, exposure end, and read-out of accumulated electric charge row by row in order from an upper part (first row) of the pixel array unit <NUM>. Even if exposure periods are the same across the respective rows, exposure periods of all the pixels for accumulating electric charge cannot coincide with one another because exposure and read-out operation are executed row by row in order, and therefore, in a case where the subject is moving, or the like, distortion occurs when capturing an image.

Meanwhile, as illustrated on a right side in <FIG>, the global shutter method is a method for performing operation covering from exposure start to exposure end on all the pixels of the pixel array unit <NUM> simultaneously, and performing reading in order from the upper part of the pixel array unit <NUM> after the exposure end. With the global shutter method, the exposure periods of all the pixels coincide with one another, and therefore, distortion does not occur even in a case such as where the subject is moving.

Operation of a pixel <NUM> by the global shutter method will be briefly described with reference to <FIG>.

First, before exposure is started, the discharge transistor <NUM> is turned on by a discharge signal OFG at High level being supplied to the discharge transistor <NUM>, and electric charge accumulated in the photodiode <NUM> is discharged to the constant voltage source VDD, by which the photodiode <NUM> is reset.

After the photodiode <NUM> is reset, when the discharge transistor <NUM> is turned off by a discharge signal OFG at a Low level, exposure is started in all the pixels.

When a predetermined exposure time has elapsed, as illustrated in A of <FIG>, electric charge corresponding to an amount of received light is generated and accumulated in the photodiode <NUM>. Then, as illustrated in B of <FIG>, in all the pixels of the pixel array unit <NUM>, the first transfer transistor <NUM> is turned on by the transfer signal TRX, and the electric charge accumulated in the photodiode <NUM> is transferred to the memory unit <NUM>.

After the first transfer transistor <NUM> is turned off, the electric charge held in the memory unit <NUM> of each of the pixels <NUM> is sequentially read to a column signal processing circuits <NUM> row by row. In read-out operation, as illustrated in C of <FIG>, the second transfer transistor <NUM> of the pixel <NUM> on a read row is turned on by a transfer signal TRG, and electric charge held in the memory unit <NUM> is transferred to the FD <NUM>. Then, when the selection transistor <NUM> is turned on by a selection signal SEL, a signal indicating a level corresponding to the electric charge held in the FD <NUM> is output from the amplification transistor <NUM> to the column signal processing circuit <NUM> via the selection transistor <NUM>.

Before describing driving of the solid-state imaging device <NUM> that achieves blackout free, other drivings that achieve blackout free will be briefly described as comparative examples.

Note that the drivings described with reference to <FIG> and <FIG> can also be executed by the solid-state imaging device <NUM> under a certain condition such as a set frame rate, and therefore will be described as being executed by the solid-state imaging device <NUM>.

Hereinafter, it is assumed that a vertical synchronization signal corresponding to a frame rate of <NUM> fps is supplied to the pixel array unit <NUM>, and exposure and read-out of all the pixels of the pixel array unit <NUM> are performed on the basis of the vertical synchronization signal.

<FIG> is a conceptual diagram illustrating a first driving method as a comparative example that achieves blackout free.

The first driving method is a method for simply generating a still image as an image for recording by exposure and read-out of all the pixels of the pixel array unit <NUM> at a frame rate of <NUM> fps, and causing the display unit <NUM> to display (LV display) the still image as a live view image at the same speed. Although there is no problem with this driving method in a case where the frame rate is relatively low, such as <NUM> fps, the circuit increases in scale and power consumption also increases as the frame rate increases, such as <NUM> fps or <NUM> fps. Furthermore, in a case where the frame rate is too low, such as <NUM> fps, the live view image seems to be discontinuous images in frame-by-frame advance.

<FIG> is a conceptual diagram illustrating a second driving method as a comparative example that achieves blackout free.

The second driving method is a method for generating a live view image by thinned read-out and displaying the live view image on the display unit <NUM> separately from a still image as an image for recording to be recorded in the recording unit <NUM>. Although both a still image obtained by exposure and read-out of all the pixels and an image for a live view image obtained by thinned read-out can be displayed on the display unit <NUM> by this driving method, it is necessary to switch between driving for an image for recording and driving for the live view image, and an image cannot be generated at a time of mode switching. Therefore, as illustrated in <FIG>, an image is not generated one in every two vertical synchronization timings, and therefore, a frame rate for the live view image displayed on the display unit <NUM> is <NUM> fps, which corresponds to half of the frame rate of the vertical synchronization signal. If an image is to be displayed on the display unit <NUM> at a frame rate (<NUM> fps) similar to the frame rate in the first driving method, pixel read-out at twice speed is required, and also power consumption increases due to high-speed driving.

Accordingly, because it is necessary to read an image with high-speed driving in both the first driving method and the second driving method in <FIG> and <FIG> respectively, a circuit for high-speed read-out is required, and power consumption increases.

Next, a driving method by the solid-state imaging device <NUM> that achieves blackout free will be described with reference to <FIG>. The driving method described below will be referred to as a third driving method.

In the third driving method, the solid-state imaging device <NUM> exposes all the pixels of the pixel array unit <NUM> at the same exposure timing and performs thinned read-out <NUM>(N -<NUM>) times in which all the pixels are thinned to <NUM>/N (N is a natural number), by which the solid-state imaging device <NUM> reads electric charge in all the pixels of the pixel array unit <NUM>, the electric charge being generated at the same exposure timing, and records the electric charge in the recording unit <NUM> as a still image.

<FIG> illustrates an example of a case where N = <NUM>, that is <NUM>/<NUM> thinned read-out, which thins out electric charge in all the pixels exposed at the same exposure timing to <NUM>/<NUM>, is performed eight times, by which a still image is output and recorded in the recording unit <NUM>. In the <NUM>/<NUM> thinned read-out, <NUM>/<NUM> thinned read-out is performed eight times as one sequence, by which one still image exposed at the same exposure timing is output to the imaging device <NUM>.

In <FIG>, time t1, t2, t3,. indicate read-out timings of the pixel array unit <NUM> according to a vertical synchronization signal of the frame rate of <NUM> fps.

First, the solid-state imaging device <NUM> performs exposure on all pixel rows of the pixel array unit <NUM> for the same exposure period in one vertical scanning period from time t1 to t2. Pixel data <NUM> illustrated on a leftmost side in <FIG> indicates that electric charge is accumulated in each of the pixels <NUM> of the pixel array unit <NUM> after an exposure period ends in time t1 to t2.

After the exposure period ends, the solid-state imaging device <NUM> performs <NUM>/<NUM> thinned read-out in which all the pixel rows of the pixel array unit <NUM> are read at intervals of five rows (every five rows). By the <NUM>/<NUM> thinned read-out in the period from the time t1 to t2, (<NUM> + 5p)-th pixel rows (p = <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. , and so on) of the pixel array unit <NUM> are sequentially read row by row from a first pixel row. Pixel data <NUM> indicates pixel rows read by the <NUM>/<NUM> thinned read-out during the time t1 to t2.

In the imaging device <NUM>, pixel signals on the respective pixel rows read by the <NUM>/<NUM> thinned read-out during the time t1 to t2 are utilized as parts of a still image as an image for recording, and as a live view image as an image for display.

In next one vertical scanning period from the time t2 to t3, the solid-state imaging device <NUM> performs next <NUM>/<NUM> thinned read-out. By the <NUM>/<NUM> thinned read-out during this period, (<NUM> + 5p)-th pixel rows of the pixel array unit <NUM> are sequentially read row by row from a second pixel row. Pixel data <NUM> indicates pixel rows read by the <NUM>/<NUM> thinned read-out during the time t2 to t3.

In the imaging device <NUM>, pixel signals on the respective pixel rows read by the <NUM>/<NUM> thinned read-out during the time t2 to t3 are utilized as parts of a still image as an image for recording.

In next one vertical scanning period from the time t3 to t4, the solid-state imaging device <NUM> performs exposure and read-out of (<NUM> + 5p)-th pixel rows, which are the same as the rows read at the time t1. That is, the solid-state imaging device <NUM> performs exposure and read-out by using only pixel rows, among all the pixel rows of the pixel array unit <NUM>, from which pixel signals for the still image have already been read. Pixel data <NUM> indicates pixel rows read by the <NUM>/<NUM> thinned read-out during the time t3 to t4. In the pixel data <NUM>, each of the pixels are represented by a pattern (dots) different from hatching. This indicates that read pixel signals are pixel signals different from the pixel signals for the still image generated at the time t1.

In the imaging device <NUM>, pixel signals on the respective pixel rows read by the <NUM>/<NUM> thinned read-out during the time t3 to t4 are utilized as parts of the live view image as the image for display.

In next one vertical scanning period from the time t4 to t5, the solid-state imaging device <NUM> performs next <NUM>/<NUM> thinned read-out. By the <NUM>/<NUM> thinned read-out during this period, (<NUM> + 5p)-th pixel rows of the pixel array unit <NUM> are sequentially read row by row from a third pixel row. Pixel data <NUM> indicates pixel rows read by the <NUM>/<NUM> thinned read-out during the time t4 to t5.

In the imaging device <NUM>, pixel signals on the respective pixel rows read by the <NUM>/<NUM> thinned read-out during the time t4 to t5 are utilized as parts of a still image as an image for recording.

In next one vertical scanning period from the time t5 to t6, the solid-state imaging device <NUM> performs exposure and read-out of (<NUM> + 5p)-th pixel rows, which are the same as the rows read at the time t1. That is, the solid-state imaging device <NUM> performs exposure and read-out by using only pixel rows, among all the pixel rows of the pixel array unit <NUM>, from which pixel signals for the still image have already been read. Pixel data <NUM> indicates pixel rows read by the <NUM>/<NUM> thinned read-out during the time t5 to t6. In the pixel data <NUM>, each of the pixels are represented by a pattern (diagonal lattice) different from hatching. This indicates that read pixel signals are pixel signals different from the pixel signals for the still image generated at the time t1.

In the imaging device <NUM>, pixel signals on the respective pixel rows read by the <NUM>/<NUM> thinned read-out during the time t5 to t6 are utilized as parts of the live view image as the image for display.

In next one vertical scanning period from the time t6 to t7, the solid-state imaging device <NUM> performs next <NUM>/<NUM> thinned read-out. By the <NUM>/<NUM> thinned read-out during this period, (<NUM> + 5p)-th pixel rows of the pixel array unit <NUM> are sequentially read row by row from a fourth pixel row. Pixel data <NUM> indicates pixel rows read by the <NUM>/<NUM> thinned read-out during the time t6 to t7.

In the imaging device <NUM>, pixel signals on the respective pixel rows read by the <NUM>/<NUM> thinned read-out during the time t6 to t7 are utilized as parts of a still image as an image for recording.

In next one vertical scanning period from the time t7 to t8, the solid-state imaging device <NUM> performs exposure and read-out of (<NUM> + 5p)-th pixel rows, which are the same as the rows read at the time t1. That is, the solid-state imaging device <NUM> performs exposure and read-out by using only pixel rows, among all the pixel rows of the pixel array unit <NUM>, from which pixel signals for the still image have already been read. Pixel data <NUM> indicates pixel rows read by the <NUM>/<NUM> thinned read-out during the time t7 to t8. In the pixel data <NUM>, each of the pixels are represented by a pattern (lattice) different from hatching. This indicates that read pixel signals are pixel signals different from the pixel signals for the still image generated at the time t1.

In the imaging device <NUM>, pixel signals on the respective pixel rows read by the <NUM>/<NUM> thinned read-out during the time t7 to t8 are utilized as parts of the live view image as the image for display.

In next one vertical scanning period from the time t8 to t9, the solid-state imaging device <NUM> performs next <NUM>/<NUM> thinned read-out. By the <NUM>/<NUM> thinned read-out during this period, (<NUM> + 5p)-th pixel rows of the pixel array unit <NUM> are sequentially read row by row from a fifth pixel row. Pixel data <NUM> indicates pixel rows read by the <NUM>/<NUM> thinned read-out during the time t8 to t9.

In the imaging device <NUM>, pixel signals on the respective pixel rows read by the <NUM>/<NUM> thinned read-out during the time t8 to t9 are utilized as parts of a still image as an image for recording.

As described above, in the <NUM>/<NUM> thinned read-out, <NUM>/<NUM> thinned read-out is performed eight times as one sequence, by which one still image exposed at the same exposure timing is output to the imaging device <NUM>.

In one sequence, the solid-state imaging device <NUM> repeats exposure at a frame rate of <NUM> fps, which is half of <NUM> fps, for <NUM>/<NUM> of the pixel rows of the pixel array unit <NUM>. Then, the solid-state imaging device <NUM> performs reading of electric charge in pixel rows exposed at the same exposure timing in a first one vertical scanning period (time t1 to t2) of one sequence, and read-out of electric charge in a pixel row exposed at a frame rate of <NUM> fps alternately in the one vertical scanning period. The pixel rows on which exposure is repeated at the frame rate of <NUM> fps are pixel rows read at an odd-numbered time among the eight times of <NUM>/<NUM> thinned read-out from time t1 to t9, and are the same pixel rows.

In each of the pixels <NUM> in the (<NUM> + 5p)-th pixel rows on which exposure is repeatedly performed at a frame rate of <NUM> fps, resetting of the photodiode <NUM> and the FD <NUM>, generation of electric charge corresponding to an amount of received light, transfer to and holding in the memory unit <NUM>, and transfer to and read-out from the FD <NUM> are executed in one vertical scanning period.

In each of the pixels <NUM> in the pixel rows read at an even-numbered time in one sequence, after electric charge corresponding to the amount of received light is transferred to the memory unit <NUM> in one vertical scanning period from time t1 to t2, the electric charge is held as is in the memory unit <NUM> until one vertical scanning period of a read-out timing. Then, when the one vertical scanning period of the read-out timing has come, the electric charge held in the memory unit <NUM> is transferred to the FD <NUM> and read.

As illustrated in <FIG>, the recording unit <NUM> of the imaging device <NUM> records a still image <NUM> generated by being output in five parts at a frame rate of <NUM> fps, which is half of <NUM> fps, by signal output from the solid-state imaging device <NUM> during the above-described eight vertical scanning periods of time t1 to t9 (one sequence).

Furthermore, the display unit <NUM> of the imaging device <NUM> sequentially displays live view images <NUM> to <NUM> having resolution of <NUM>/<NUM> of full resolution of the pixel array unit <NUM> and being updated at a frame rate of <NUM> fps, which is half of <NUM> fps.

<FIG> illustrates an example of a case where N = <NUM>, that is <NUM>/<NUM> thinned read-out, which thins out electric charge in all the pixels exposed at the same exposure timing to <NUM>/<NUM>, is performed six times, by which a still image is output.

In the <NUM>/<NUM> thinned read-out, one sequence includes six times of <NUM>/<NUM> thinned read-out, and one still image exposed at the same exposure timing is output to the imaging device <NUM> by performing <NUM>/<NUM> thinned read-out six times.

Pixel data <NUM> obtained by exposure in one vertical scanning period from time t11 to t12 is divided into pixel data <NUM> obtained by <NUM>/<NUM> thinned read-out during a first time period from the time t11 to t12, pixel data <NUM> obtained by <NUM>/<NUM> thinned read-out during a second time period from the time t12 to t13, pixel data <NUM> obtained by <NUM>/<NUM> thinned read-out during a fourth time period from time t14 to t15, and pixel data <NUM> obtained by <NUM>/<NUM> thinned read-out during a sixth time period from time t16 to t17, output to the imaging device <NUM> in order, and recorded as one still image in the recording unit <NUM> of the imaging device <NUM>.

Meanwhile, the pixel data <NUM> obtained by the <NUM>/<NUM> thinned read-out during the first time period from the time t11 to t12, pixel data <NUM> obtained by <NUM>/<NUM> thinned read-out during a third time period from the time t13 to t14, and pixel data <NUM> obtained by <NUM>/<NUM> thinned read-out during a fifth time period from the time t15 to t16 are sequentially output to the imaging device <NUM>, and displayed as a live view image on the display unit <NUM> of the imaging device <NUM>.

Here, the pixel rows are read at intervals of five rows during one vertical scanning period in the <NUM>/<NUM> thinned read-out illustrated in <FIG>, whereas intervals of two rows and intervals of four rows are alternately arranged in the <NUM>/<NUM> thinned read-out in <FIG>. In other words, in the <NUM>/<NUM> thinned read-out illustrated in <FIG>, the <NUM>/<NUM> thinned read-out is repeatedly executed in the vertical direction, whereas, in the <NUM>/<NUM> thinned read-out in <FIG>, <FIG>/<FIG> thinned read-out and <NUM>/<NUM> thinned read-out are alternately repeatedly executed in the vertical direction, achieving <NUM>/<NUM> thinned read-out. This is because of the following reasons.

In an image sensor with the Bayer pattern, if read-out is performed at intervals of N rows in a case where N in <NUM>/N thinning is an even number as in the <NUM>/<NUM> thinned read-out or <NUM>/<NUM> thinned read-out, only either RG pixel rows, which are pixel rows of red pixels and green pixels, or GB pixel rows, which are pixel rows of green pixels and blue pixels, are read, and unevenness occurs in color information for a live view image. Therefore, in <NUM>/N thinned read-out in a case where N is an even number, the solid-state imaging device <NUM> performs the <NUM>/N thinned read-out on the pixel array unit <NUM> as a whole by alternately performing <NUM>/(N -<NUM>) thinned read-out and <NUM>/(N + <NUM>) thinned read-out. With this arrangement, the RG pixel rows and the GB pixel rows can be alternately read, and unevenness of color information in the live view image can be prevented from occurring.

<FIG> illustrates an example of a case where N = <NUM>, that is <NUM>/<NUM> thinned read-out, which thins out electric charge in all the pixels exposed at the same exposure timing to <NUM>/<NUM>, is performed four times, by which a still image is output.

In the <NUM>/<NUM> thinned read-out, one sequence includes four times of <NUM>/<NUM> thinned read-out, and one still image exposed at the same exposure timing is output to the imaging device <NUM> by performing <NUM>/<NUM> thinned read-out four times.

Pixel data <NUM> obtained by exposure in one vertical scanning period from time t21 to t22 is divided into pixel data <NUM> obtained by <NUM>/<NUM> thinned read-out during a first time period from the time t21 to t22, pixel data <NUM> obtained by <NUM>/<NUM> thinned read-out during a second time period from the time t22 to t23, and pixel data <NUM> obtained by <NUM>/<NUM> thinned read-out during a fourth time period from time t24 to t25, output to the imaging device <NUM> in order, and recorded as one still image in the recording unit <NUM> of the imaging device <NUM>.

Meanwhile, the pixel data <NUM> obtained by the <NUM>/<NUM> thinned read-out during the first time period from the time t21 to t22 and pixel data <NUM> obtained by <NUM>/<NUM> thinned read-out during a third time period from the time t33 to t34 are sequentially output to the imaging device <NUM>, and displayed as a live view image on the display unit <NUM> of the imaging device <NUM>.

Because the <NUM>/<NUM> thinned read-out in <FIG> is <NUM>/N thinned read-out in a case where N is an odd number, pixel rows are read at intervals of three rows during one vertical scanning period similar to the <NUM>/<NUM> thinned read-out illustrated in <FIG>.

As described above, in the <NUM>/N thinned read-out, one sequence includes <NUM>/N thinned read-out of <NUM>(N - <NUM>) times, and one still image exposed at the same exposure timing is output to the imaging device <NUM> by performing <NUM>/N thinned read-out <NUM>(N - <NUM>) times. In <NUM>/N thinned read-out in a case where N is an odd number, the solid-state imaging device <NUM> repeats read-out at intervals of N rows in the vertical direction, and in <NUM>/N thinned read-out in a case where N is an even number, the solid-state imaging device <NUM> alternately performs reading at intervals of (N -<NUM>) rows and reading at intervals of (N + <NUM>) rows in the vertical direction.

Furthermore, every other one vertical scanning period, the solid-state imaging device <NUM> alternately performs reading of electric charge in a pixel row exposed at the same exposure timing and reading of electric charge in a pixel row repeatedly exposed at a frame rate of <NUM> fps, which is half of <NUM> fps, for <NUM>/N pixel rows of the pixel array unit <NUM>. The pixel rows on which exposure is repeated at the frame rate of <NUM> fps, which is half of <NUM> fps, are pixel rows read at an odd-numbered time among the <NUM>/N thinned read-out of <NUM>(N -<NUM>) times, and are the same pixel rows.

<FIG> is a table comparing read-out speeds of the first to third driving methods.

As illustrated in <FIG>, cases where a frame rate for a live view image displayed on the display unit <NUM> of the imaging device <NUM> (displayed frame rate) is set to, for example, <NUM> fps, <NUM> fps, and <NUM> fps are compared.

According to the first driving method, the solid-state imaging device <NUM> needs to read and output an image at the same speed as a displayed frame rate. That is, in the first driving method, read-out speeds corresponding to the displayed frame rates of <NUM> fps, <NUM> fps, and <NUM> fps are <NUM> fps, <NUM> fps, and <NUM> fps, respectively.

According to the second driving method, the solid-state imaging device <NUM> needs to read and output an image at twice speed of a displayed frame rate. That is, in the second driving method, read-out speeds corresponding to the displayed frame rates of <NUM> fps, <NUM> fps, and <NUM> fps are <NUM> fps, <NUM> fps, and <NUM> fps, respectively.

Meanwhile, according to the third driving method, as described with reference to <FIG>, in a case of <NUM>/<NUM> thinned read-out, display is performed at a frame rate of <NUM> fps, which is half of <NUM> fps, and the read-out speed corresponds to <NUM>/<NUM> = <NUM> fps at this time, because <NUM>/<NUM> thinned read-out is performed,. That is, read-out speed corresponding to the displayed frame rate of <NUM> fps is <NUM> fps. Accordingly, in the third driving method, read-out frame rates corresponding to the displayed frame rates of <NUM> fps, <NUM> fps, and <NUM> fps are <NUM> fps, <NUM> fps, and <NUM> fps, respectively.

As described above, according to the third driving method, it is not necessary to perform reading at an excessively high speed, and blackout free can be achieved by low-speed read-out. Because high-speed read-out is not required, power consumption can be reduced, and a circuit for high-speed read-out can be eliminated, by which the solid-state imaging device <NUM> can be manufactured at a low cost.

Processing by the imaging device <NUM> corresponding to output of a still image and live view image from the solid-state imaging device <NUM> according to the third driving method will be described.

According to the imaging mode or the like set in the operation unit <NUM> by the user, the control unit <NUM> of the imaging device <NUM> designates an operation mode in accordance with the third driving method to the solid-state imaging device <NUM> and the signal processing unit <NUM>. The operation mode in accordance with the third driving method may be designated by the control unit <NUM> to the signal processing unit <NUM>, and the signal processing unit <NUM> may designate the third driving method to the solid-state imaging device <NUM>.

When the operation mode in accordance with the third driving method is designated, as described above, the solid-state imaging device <NUM> performs all-pixel exposure at the same exposure timing in the first one vertical scanning period of one sequence. Then, the solid-state imaging device <NUM> performs <NUM>/N thinned read-out for a live view image as an image for display in one vertical scanning period at an odd-numbered time in one sequence, and performs <NUM>/N thinned read-out for a still image as an image for recording in one vertical scanning period at an even-numbered time in the one sequence. However, first data for the live view image in the one sequence also serves as data for the still image.

When the operation mode in accordance with the third driving method is designated, the signal processing unit <NUM> identifies that data for the still image and live view image is supplied from the solid-state imaging device <NUM> in the above-described order, and performs processing corresponding to the supplied image data. Specifically, in a case where data for the live view image is supplied from the solid-state imaging device <NUM>, the signal processing unit <NUM> supplies the data to the display unit <NUM> and causes the display unit <NUM> to display the data. Furthermore, in a case where data for the still image is supplied from the solid-state imaging device <NUM>, the signal processing unit <NUM> supplies the data to the recording unit <NUM> and causes the recording medium to record the data. Data for both the live view image and the still image is supplied to both the display unit <NUM> and the recording unit <NUM>.

By using the solid-state imaging device <NUM> to which the above-described embodiment is applied, blackout free can be achieved in the imaging device <NUM>.

Depending on the imaging mode or the like designated with the operation unit <NUM> by the user, the control unit <NUM> of the imaging device <NUM> can also designate an operation mode in accordance with the above-described first driving method or second driving method to the solid-state imaging device <NUM> and the signal processing unit <NUM> to cause the solid-state imaging device <NUM> and the signal processing unit <NUM> to operate.

Although the above-described pixel circuit of a pixel <NUM> includes the memory unit <NUM> that holds electric charge generated by the photodiode <NUM> until a read-out timing comes, the above-described third driving method may be executed by using a circuit configuration not including the memory unit <NUM> as the pixel circuit of the pixel <NUM>. In this case, electric charge generated by the photodiode <NUM> is held in the FD <NUM> until the read-out timing comes.

Although an embodiment of an imaging device including a solid-state imaging device to which the present technology is applied has been described above, the present technology can be applied to an electronic apparatus other than an imaging device including a solid-state imaging device, which is for example, a mobile terminal device having an imaging function such as a smartphone, a personal computer, a game machine, a wearable terminal, or the like.

Embodiments of the present technology are not limited to the above-described embodiments, and various changes can be made without departing from the scope of the present technology.

For example, parts of the embodiment described above may be used in combination as appropriate.

Claim 1:
A solid-state imaging device (<NUM>) comprising:
a pixel array unit (<NUM>) in which a plurality of pixels (<NUM>) is two-dimensionally arranged in a matrix; and
a control unit (<NUM>) that exposes all pixels of the pixel array unit at a same exposure period and performs thinned read-out <NUM>(N -<NUM>) times in which all the pixels are thinned to <NUM>/N in a vertical direction, where N is a natural number >= <NUM>, so as to read electric charge in all the pixels of the pixel array unit, the electric charge being generated at the same exposure period;
wherein, every other one vertical scanning period, the control unit alternately performs reading of electric charge in a first pixel row exposed at the same exposure period and reading of electric charge in a second pixel row repeatedly exposed at a predetermined frame rate;
and wherein the control unit repeats exposure at the predetermined frame rate on the second pixel row of the pixel array unit.