Imaging device

Abstract

To solve a problem that AF / AE accuracy of a dark part in output channels for evaluation value acquisition deteriorates.SOLUTION: The present invention comprises a pixel unit that includes a first and a second pixel group composed of a plurality of pixels, a first output channel that outputs an image signal obtained from the first pixel group, and a second output channel that outputs an image signal obtained from the second pixel group, means for determining a saturation state of the second image from an evaluation value obtained from the first or the second image read out respectively via the first or the second output channel, and means for determining storage time and read-out counts of the second channel so as to avoid the saturation of the second image, in accordance with the saturation determination results.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an imaging device.

Background Art

[0002] In imaging devices typified by digital cameras and the like, in order to confirm in advance the angle of view, brightness, etc. of the subject to be photographed, the images continuously read out from the imaging element are processed and output to a display device such as an LCD panel for live view (LV) display. This has become common practice. For the brightness displayed in LV, automatic exposure (AE) is generally performed so that it is the same as when shooting a still image. As a result, the shooting operation can be performed with an image as intended by the user.

[0003] For example, if you want to set the exposure to be slightly darker than the AE result, by performing a -2 stop setting for exposure correction, the LV display will also change to a display with an exposure about 2 stops darker than the proper exposure.

[0004] Thus, when deliberately shooting with underexposure, when starting the autofocus (AF) operation by half-pressing the release button, the LV display image may momentarily brighten. This is because control is performed to increase the amount of signal obtained from the imaging element in order to ensure AF accuracy. That is, this phenomenon occurs because the charge accumulation time is extended to prevent a decrease in AF and AE accuracy when performing imaging surface AF to obtain an AF evaluation value based on the image read out from the imaging element for LV display.

[0005] In order to perform AF and AE without significantly changing the LV display brightness, an evaluation value may be obtained from an image different from the image for LV display. In Japanese Patent Laid-Open No. 2020-80512, an imaging device has been proposed that obtains an AF / AE evaluation value acquisition image using pixels not used for LV display and simultaneously performs flicker detection without stopping the LV display. By applying this, it is possible to prevent a decrease in AF and AE accuracy without changing the LV display brightness.

[0006] [[ID=2,7]] Furthermore, in Japanese Patent Publication No. 2016-92692, rows for image generation and rows for evaluation value acquisition are arranged alternately, and control is implemented to prevent the pixels in the focus detection row from becoming saturated and leaking charge into the image generation row. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2020-80512 [Patent Document 2] Japanese Patent Publication No. 2016-92692 [Overview of the project] [Problems that the invention aims to solve]

[0008] However, when obtaining AF evaluation values ​​using pixels not used for LV display, as in Patent Document 1, extending the accumulation time can lead to pixel saturation at a certain point. This not only prevents obtaining correct AF / AE evaluation values, but can also cause charge leakage, where the charge from saturated pixels leaks to pixels in adjacent rows. This charge leakage can degrade the display quality of the LV display image.

[0009] Furthermore, in the configuration of Patent Document 2, the adjacent focus detection row is also reset at the same time as the image generation row is reset, thereby preventing charge leakage from the focus detection row to the image generation row. However, this requires a special configuration for the reset operation in the image sensor itself.

[0010] The present invention has been made in view of the above-mentioned problems, and its objective is to provide an imaging device that can maintain AF / AE accuracy while reducing image quality degradation caused by discontinuously selecting and reading out physically adjacent rows of the image sensor. [Means for solving the problem]

[0011] The imaging apparatus of the present invention comprises a pixel section including a first pixel group and a second pixel group different from the first pixel group, and obtained from the first pixel group For display A first output channel that outputs an image signal, and obtained from the second pixel group For obtaining evaluation values A second output channel that outputs an image signal, and the For display Image signal or the above For obtaining evaluation values Image signal By comparing the brightness level with a predetermined threshold The aforementioned For obtaining evaluation values A saturation determination means for determining the saturation state of an image signal, and the saturation determination means If the aforementioned image signal for acquiring evaluation values ​​is close to saturation, Determined In some cases , the above For obtaining evaluation values To avoid saturation of the image signal, the second Image signal for acquiring the evaluation value in the pixel group Determine the storage time and number of read operations. Furthermore, during the blanking period when the display image signal is not read out, the second pixel group is controlled to divide the evaluation value acquisition image signal into multiple parts for storage and reading. Control means and It is characterized by having the following features. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide an imaging device that can maintain AF / AE accuracy while reducing image quality degradation caused by discontinuously selecting and reading out physically adjacent rows of the image sensor. [Brief explanation of the drawing]

[0013] [Figure 1] A schematic diagram of the imaging device in an embodiment of the present invention. [Figure 2] Pixel arrangement diagram of an image sensor in an embodiment of the present invention. [Figure 3] A schematic diagram of the LV readout row of the image sensor in an embodiment of the present invention. [Figure 4] Schematic diagram of the LV readout row and evaluation value readout row of the image sensor in an embodiment of the present invention. [Figure 5] Timing chart during AF operation in an embodiment of the present invention. [Figure 6] Flowchart for LV display in an embodiment of the present invention. [Modes for carrying out the invention]

[0014] (Embodiment) FIG. 1 shows an overview of an imaging device according to an embodiment of the present invention.

[0015] In FIG. 1, a lens unit 101 is driven by a lens driving unit 102, and controls such as zooming and focusing are performed. A mechanical shutter (referred to as a mechanical shutter) 103 and an aperture 104 are driven and controlled by a mechanical shutter - aperture driving unit (referred to as a shutter - aperture driving unit) 105. An overall control arithmetic unit 109 is a central unit that performs control and various arithmetic operations for the entire imaging device.

[0016] [[ID=K]] The subject image that has passed through the lens unit! 01 is adjusted to an appropriate amount of light by the aperture 104 and is formed on the imaging surface of the imaging element 106. The subject image formed on the imaging surface on the imaging element 106 is photoelectrically converted by the pixel 201, and further A / D conversion is performed to perform gain adjustment and conversion from an analog signal to a digital signal. Then, it is taken in as signals of R, Gr, Gb, and B and sent to the imaging signal processing circuit 107.

[0017] <00000M> The imaging signal processing circuit 107 processes the output signal of the imaging element 106. In the imaging signal processing circuit 107, predetermined arithmetic processing is performed using the captured image signal, and based on the obtained arithmetic result, the overall control arithmetic unit 109 performs exposure control and distance measurement control. In this embodiment, a saturation determination circuit that determines whether pixel saturation is likely to occur from the pixel data obtained from the imaging element 106 is included in the imaging signal processing circuit 107.

[0018] Thereby, TTL (through - the - lens) - type AE (automatic exposure) processing and EF (flash automatic light - control emission) processing are performed. By lengthening or shortening the VD signal period applied to the imaging element 106 by the AE processing, it is possible to change the frame rate. [[ID=P]]

[0019] Furthermore, the imaging signal processing circuit 107 performs predetermined calculations using the captured image signal, and TTL-type AWB (auto white balance) processing is performed based on the obtained calculation results. In addition, the imaging signal processing circuit 107 performs scratch pixel correction and shading processing on the image sensor 106, and then performs development processing. In the development processing, low-pass filtering is performed to reduce noise, sharpness correction is performed to correct subject blur, contrast correction is performed to adjust the contrast of the image, and false color correction is performed to correct false colors.

[0020] The memory unit 108 temporarily stores the image signal. The recording medium control interface unit (referred to as the recording medium control I / F unit) 110 records the image signal to the recording medium 112 or reads the image signal from the recording medium 112.

[0021] The display unit 111 displays image signals. The display unit 111 consists of two types: an EVF (Electronic View Finder) and an LCD (Liquid Crystal Display).

[0022] The recording medium 112 is a removable storage medium such as a semiconductor memory, and the recording medium control I / F unit 110 records or reads image signals.

[0023] The external interface unit 113 (referred to as the external I / F unit) is an interface for communicating with an external computer or the like. The memory unit 114 stores the calculation results from the overall control calculation unit 109.

[0024] The control unit 115 is equipped with operating elements such as menu buttons for the user to configure the imaging device and playback buttons for checking captured images. Information regarding the driving conditions of the imaging device set by the user in the control unit 115 is sent to the overall control calculation unit 109, and the entire imaging device is controlled based on this information.

[0025] In this embodiment, the imaging signal processing circuit 107 and the overall control calculation unit 109 are configured separately, but this is not the only configuration; they may be configured on the same circuit including the CPU.

[0026] Figure 2 shows an example of the configuration of the image sensor 106 in this embodiment. In the example shown in Figure 2, the image sensor 106 comprises a first semiconductor substrate (imaging layer) 20 and a second semiconductor substrate (circuit layer) 21. The first semiconductor substrate 20 is stacked on the second semiconductor substrate 21.

[0027] Multiple pixel units 201 are arranged in a two-dimensional array (matrix) on the first semiconductor substrate 20, and are positioned on the light incident side. In other words, the first semiconductor substrate 20 is located on the incident side that receives light from the subject. Each pixel unit 201 is connected to a transfer signal line 203, a reset signal line 204, and a row selection signal line 205 in the horizontal direction (row direction), and to a vertical output line 202 in the vertical direction (column direction). Note that the vertical output line 202 is connected to different destinations depending on the read row unit.

[0028] The second semiconductor substrate 21 has pixel driving circuits such as a column ADC block 211, a row scanning circuit 212, a column scanning circuit 213, and a timing control circuit 214, as well as a switching unit 216, a frame memory 217, an in-element calculation unit 218, and a P / S conversion unit 219.

[0029] In this way, the image sensor 106 has multiple pixel sections 201 formed on the first semiconductor substrate 20, and pixel driving circuits, memory circuits, arithmetic circuits, etc., formed on the second semiconductor substrate 21. Since the manufacturing process can be separated for the imaging layer and the circuit layer of the image sensor 106, it is possible to achieve higher speed, miniaturization, and enhanced functionality by making the wiring in the circuit layer thinner and denser. In addition, some of the circuits on the second semiconductor substrate 21 may be provided on the first semiconductor substrate 20.

[0030] The column ADC block 211 outputs an analog-to-digital (A / D) converted signal to the signal output from the vertical output lines 202 connected to the multiple pixel units 201. Here, signal amplification may be performed in the column ADC block 211 using the conversion gain used for digital conversion, or signal amplification may be performed after digital conversion using a digital gain circuit (not shown).

[0031] The row scanning circuit 212 is connected to each pixel unit 201 via the transfer signal line 203, the reset signal line 204, and the row selection signal line 205. Multiple column scanning circuits 213 are connected to the horizontal signal lines 215-a and 215-b. The timing control circuit 214 outputs timing control signals to the column ADC block 211 and the column scanning circuits 213, respectively, and controls them.

[0032] The switching unit 216 switches the signals from the horizontal signal lines 215-a and 215-b, which are provided for each output channel, and selectively outputs the image signals output from the horizontal signal lines 215-a and 215-b to the frame memory 217 and the in-element processing unit 218 in sequence. The frame memory 217 temporarily stores the image signals output from the horizontal signal lines 215-a and 215-b.

[0033] The in-element calculation unit 218 performs calculations such as exposure control within the image sensor 106. The in-element calculation unit 218 receives a target brightness value from the overall control calculation unit 509 and calculates the storage time of the pixel unit 201 and its gain for that output signal based on the signal output by the switching unit 216 and the received target brightness value.

[0034] The parallel / serial conversion unit (hereinafter referred to as the P / S conversion unit) 219 performs parallel / serial conversion on the image information processed by the in-element calculation unit 218 in accordance with the timing control signal from the timing control circuit 214. The serially converted image information is then output to the imaging signal processing circuit 107 outside the image sensor 106.

[0035] Next, referring to Figure 3, the readout operation of the image signal for LV display and the readout operation of the image signal for evaluation value acquisition of the image sensor 106 while it is in standby mode will be explained. Figure 3 shows a part of the arrangement of the pixel units 201 in the image sensor 106, and each subscript indicates the color of the color filter provided in each of the pixel units 201 (R: Red, Gr / Gb: Green, B: Blue).

[0036] Figure 3 also shows the arrangement of the pixel units 201 and which row of signals is targeted for reading during the LV display image signal readout operation. In the actual image sensor 106, there are pixel units 201 corresponding to the number of pixels, but for explanatory purposes only, only 2 columns and 15 rows are shown here.

[0037] The LV display image signal readout operation refers to the operation of continuously reading out image signals for display on the LCD or EVF included in the display unit 111, and is used for the user to determine the angle of view and shooting conditions such as exposure conditions. In other words, it is not stored on the recording medium 112, and since the number of pixels in the rear LCD, etc. is less than the number of pixels in the image sensor 106, it is not necessary to read out image signals from all pixels 201.

[0038] Therefore, it is common practice to reduce the number of pixels to a level comparable to the number of pixels or rows on an LCD or similar display before reading the image. For example, if the image sensor 106 has an effective number of pixels of 6000 horizontally and 4000 vertically, the number of pixels in the vertical direction is reduced to one-fifth in order to obtain sufficient resolution for display on the display unit 111.

[0039] In this embodiment, an example is shown in which three rows of readout are downsampled in a five-row cycle, and the pixel signals of the remaining two rows are added together for output. More specifically, in Figure 3, the pixel count is reduced by downsampling in the row direction in each of the Red row, which includes a pixel section 201 with an R color filter, and the Blue row, which includes a pixel section 201 with a B color filter, in a five-row cycle.

[0040] The 5-row period and the method of reading out by averaging two of those rows are just examples; other periods are also acceptable, such as reading out by averaging two of the pixel signals with a 3-row period. Furthermore, the pixel signal summing method can be simple summing or averaging. While the method of summing two rows of signals assumes an averaging method where different rows are simultaneously connected to the vertical output line 202, the averaging method between rows is not limited to this.

[0041] Next, we will describe the pixel rows that are read when the user performs a half-press operation of the release button (not shown) on the control unit 115 as a release preparation operation (hereinafter referred to as SW1 press).

[0042] When SW1 is pressed, the autofocus operation is performed to focus on a predetermined AF frame. While I won't go into detail here, there are various methods for autofocus operation.

[0043] For example, there is a contrast method that considers the position where the contrast of a certain region in the image signal of the image sensor, or the high-frequency component of the spatial frequency, is maximum as the in-focus position, and controls the focusing lens so that the image is in focus at that position.

[0044] Another example is the phase-detection autofocus system, which captures two images that have passed through different points on the photographic lens using an AF sensor, and recognizes the amount of focus shift as the difference in distance between the images on the AF sensor.

[0045] Furthermore, more recently, there is a further evolution of the phase-detection method called the image sensor-plane phase-detection method, which performs phase-detection AF by acquiring two different data points on the image sensor surface. In this embodiment, it is assumed that AF is performed using either the contrast method or the image sensor-plane phase-detection method.

[0046] In this embodiment, evaluation values ​​used for AF and AE are obtained based on an image signal separate from the LV display image signal during shooting standby. For example, when shooting with underexposure, by extending the charge accumulation time when SW1 is pressed to ensure AF / AE accuracy and obtain appropriate AF / AE evaluation values, the phenomenon of the displayed LV image becoming momentarily bright can be avoided.

[0047] In other words, in this embodiment, in order to avoid a decrease in AF / AE accuracy without changing the LV display brightness when SW1 is pressed, the image signal for acquiring AF / AE evaluation values ​​is read out in parallel with the image signal for LV display.

[0048] Figure 4 shows which row of signals will be read out in order to read out the image signal for LV display and the image signal for acquiring AF / AE evaluation values ​​in parallel after pressing SW1.

[0049] The pixel section 201 shown by the shaded area in Figure 4 is a portion of the non-readout row in the LV during shooting standby in Figure 3, which has been changed to a readout row. This allows for parallel reading of the image signal for LV display and the image signal for acquiring AF / AE evaluation values. Of the three consecutive rows that were non-readout rows in Figure 3, the pixel section 201 of the central row is designated as the pixel row for acquiring AF / AE evaluation values. Therefore, even if pixel saturation occurs in this row, the pixel sections 201 of the adjacent row are non-readout rows, minimizing the impact of charge leakage on the LV display image.

[0050] In this embodiment, the pixel signals output from the pixel row for LV display images (first pixel group) and the pixel row for AF / AE evaluation value acquisition (second pixel group) are processed using a common column scanning circuit 213. Therefore, the readout timing to the column scanning circuit 213 is controlled mutually. Then, during the blanking period, when readout scanning of the LV display image signal is not being performed, the image signals of the pixel rows that are not readout for LV display are readout, so that two images acquired at almost the same timing can be obtained within a 1V period.

[0051] Figure 5 shows the timing chart for when SW1 is pressed to perform AF operation via image sensor AF while the LV display is in standby mode for shooting. For simplicity, this explanation assumes that there is no change in subject brightness before and after pressing SW1, but if, for example, the subject brightness increases, underexposure compensation may be applied to the image signal for LV display.

[0052] Ch1_VD is the vertical synchronization signal used when reading the LV display image signal Ch1 from the image sensor 106, and is read out at, for example, 16.7ms (equivalent to 60fps). The LV display image signal Ch1 is read out from the image sensor 106 in synchronization with this vertical synchronization signal Ch1_VD. The storage time within the image sensor 106 is controlled according to the instructions of the overall control calculation unit 109, but since the subject brightness does not change, the storage time remains e1 before and after pressing SW1 and does not change.

[0053] Ch2_VD is the vertical synchronization signal used when reading out the AF / AE evaluation value acquisition image signal Ch2 from the image sensor 106, and can operate at a period of 4.2ms, which is one-quarter the period of the vertical synchronization signal Ch1_VD. In this embodiment, due to the circuit configuration of the image sensor shown in Figure 2, it is possible to read out the AF / AE evaluation value acquisition image signal Ch2 during the period when the LV display image signal Ch1 is not being read out, i.e., during the V blanking period of the LV display image signal Ch1. However, it is not possible to read out the LV display image signal Ch1 and the AF / AE evaluation value acquisition image signal Ch2 simultaneously.

[0054] Figure 6 shows a flowchart illustrating the process of performing autofocus (AF) operation via image sensor AF when SW1 is pressed while the LV display is in standby mode for shooting.

[0055] When the user powers on the imaging device using the control unit 115 and starts it up, the system performs initialization operations before the LV display starts in S501. Specifically, these operations include opening and closing the mechanical shutter 103, resetting the lens 101, and moving it to its initial position. This process is executed by the built-in program based on instructions from the overall control calculation unit 109, but the subsequent processes are similar, so a detailed explanation is omitted.

[0056] In S502, the storage time of the LV display image signal Ch1 of the image sensor 106 is set to e1 in order to output an image for LV display.

[0057] In S503, the LV display image signal Ch1 is continuously read out, calculations are performed in the imaging signal processing circuit 107 and the overall control calculation unit 109, and then output to the display unit 111 to start the LV display during the shooting standby.

[0058] In S504, it is determined whether to terminate the LV display by the user turning off the power switch from the control unit 115. If there is an instruction to terminate the LV display, the LV display is terminated. If the LV display is not terminated, the process proceeds to S505, where it is determined whether or not SW1 was pressed.

[0059] If SW1 is not pressed, the process proceeds to S506, stopping the accumulation and reading of the AF / AE evaluation value image signal Ch2, and returns to S505. Also, in S505, if SW1 is pressed, the process proceeds to S507, where the settings for reading the AF / AE evaluation value image signal Ch2 are made to the image sensor 106.

[0060] In S507, the storage time for the AF / AE evaluation value image signal Ch2 is set to e1, similar to the LV display image signal Ch1, and the number of readouts n for the AF / AE evaluation value image signal Ch2 is set to 1. This process results in a state where the AF / AE evaluation value image signal is acquired using pixel rows not used for LV display while LV display is being performed.

[0061] When SW1 is pressed at time t0 in Figure 5, the overall control calculation unit 109 controls the accumulation of the AF / AE evaluation value image signal Ch2 at time t1, and the accumulation is performed for the same accumulation time e1 as the LV display image signal Ch1, after which the accumulated image signal Ch2 is read out.

[0062] In S508, exposure control is performed for the AF / AE evaluation value image signal Ch2. Specifically, brightness information is acquired from the AF / AE evaluation value image signal Ch2, which has been accumulated and read out since time t1 in Figure 5, by predetermined calculation processing in the imaging signal processing circuit 107 and the overall control calculation unit 109. The brightness information acquired here may be within a preset AF frame, or within a frame of the subject position estimated by calculation from the entire image. Then, exposure control of the AF / AE evaluation value image signal Ch2 is performed based on the acquired brightness information.

[0063] In S509, based on the exposure control result in S508, the accumulation time of the AF / AE evaluation value image signal Ch2 is set to e2. That is, the overall control calculation unit 109 performs control to extend the accumulation time of the AF / AE evaluation value image signal Ch2, which is accumulated from time t2 in Figure 5, to e2.

[0064] In S510, the AF / AE evaluation value image signal Ch2 is read once, and predetermined calculations are performed in the imaging signal processing circuit 107 and the overall control calculation unit 109. If the storage time is long, there is a high risk that charge will leak to adjacent LV display pixel rows, degrading the LV display image quality. Therefore, the saturation determination unit in the imaging signal processing circuit 107 determines whether the read AF / AE evaluation value image signal Ch2 is close to saturation.

[0065] As a method of determination, for example, the value of the image signal (RAW data) itself, read from the image sensor 106 before signal processing, can be compared with a predetermined threshold, and if it exceeds the threshold, it can be determined that the image is close to pixel saturation. Alternatively, the image signal for one screen can be divided, and the average level of the RAW data for each division can be compared with the threshold, or an evaluation value obtained by performing a predetermined calculation on the RAW data can be compared with the threshold. However, when determining the saturation state, it is preferable to use the RAW data before any corrections are applied within the image signal processing circuit 107.

[0066] In Figure 5, the dotted line shows the threshold for pixel saturation detection of the AF / AE evaluation value image signal Ch2. Since the AF / AE evaluation value image signal Ch2, which has been accumulated and read out from time t1, is below the threshold, it is determined that it is not in a saturated state. Note that, in this case, since the accumulation time of the AF / AE evaluation value image signal Ch2 is the same as the accumulation time of the LV display image signal Ch1, the saturation detection itself may be omitted.

[0067] In S511, the brightness level of the AF / AE evaluation image signal Ch2 is compared with a threshold (Y-th) that has been predetermined as the output level at which saturation is a concern. If the brightness level of the AF / AE evaluation image signal Ch2 is lower than the threshold Y-th, the process returns to S504. On the other hand, if the brightness level of the AF / AE evaluation image signal Ch2 is equal to or greater than the threshold Y-th, the process proceeds to S512.

[0068] The brightness level of the AF / AE evaluation image signal Ch2, which was accumulated and read out from time t2 in Figure 5, exceeds the threshold (Y-th) and is determined to be close to saturation.

[0069] In S512, it is checked whether the accumulation timings of the LV display image signal Ch1 and the AF / AE evaluation value image signal Ch2 overlap. If they do not overlap, the process returns to S504. If they do overlap, the process proceeds to S513.

[0070] In S513, the storage time for the AF / AE evaluation value image signal Ch2 is changed from e2 to half of e2, i.e., to e3, and the number of readouts n for the AF / AE evaluation value image signal Ch2 is doubled (divided storage is performed and readout is performed multiple times). The initial value of the number of readouts n for the AF / AE evaluation value image signal Ch2 was 1, so at this stage n=2.

[0071] Then, as shown in Figure 5, during the blanking period of the LV display image signal Ch1, at times t3 and t4, the AF / AE evaluation value image signal Ch2 is continuously stored and read out, and the process proceeds to S514.

[0072] In S514, the image signals of the AF / AE evaluation value image signal Ch2, which have been divided, stored, and read out, are combined in the overall control calculation unit 109 to generate the AF / AE evaluation value image, and the process proceeds to S515.

[0073] In S515, AF control is performed using the image signal synthesized in S514, and the process returns to S504.

[0074] In this way, by combining the AF / AE evaluation value image signal Ch2 after splitting and reading it out, the pixels from which the AF / AE evaluation value image signal Ch2 is read out are controlled to prevent saturation. Therefore, it is possible to prevent deterioration of LV display image quality due to charge leakage into the LV display image signal Ch1.

[0075] Furthermore, the image signals obtained by continuously reading out the accumulated AF / AE evaluation signal Ch2 are combined to generate an AF / AE evaluation image. Compared to obtaining the evaluation value from a single frame image acquired over an accumulation time e2, a more accurate AF / AE evaluation value can be obtained.

[0076] While there are various methods for image synthesis, as described above, by dividing the accumulation time per step by half and adding the results of two separate steps, it is possible to obtain an image with nearly correct exposure, which is also suitable for maintaining the accuracy of the AF evaluation value.

[0077] Note that, depending on the shooting conditions, the accumulation of the LV display image signal Ch1 and the AF / AE evaluation value image signal Ch2 may not necessarily overlap as described above. Therefore, if it can be determined in advance that there is no overlap in accumulation, there is no risk of charge leakage to the other output channel, and it is possible to change the control so as not to perform the saturation state determination shown in this embodiment. In this case, the degree of freedom for the accumulation time of the AF / AE evaluation value image signal Ch2 increases, and since there is no need to perform image synthesis, the time lag from pressing SW1 to shooting can be shortened.

[0078] In this embodiment, when the brightness level of the AF / AE evaluation image signal Ch2 exceeds a predetermined threshold, the storage time is halved and the number of readouts is doubled to ensure that the brightness level remains unchanged after the data is combined after split storage. However, this method is not necessarily the only way to achieve this.

[0079] For example, by changing the number of divisions depending on how much the brightness level of the AF / AE evaluation image signal Ch2 exceeds the threshold Y-th, it is possible to reduce the risk of charge leakage into the LV display image.

[0080] In this embodiment, when determining saturation, the brightness level of the AF / AE evaluation value image signal Ch2 is compared with a threshold. However, the threshold may also be used to compare the threshold with the LV display image signal Ch1, or with both the LV display image signal Ch1 and the AF / AE evaluation value image signal Ch2. With such a configuration, saturation of the LV display image signal prevents charge leakage into the AF / AE evaluation value image signal, thereby preventing a decrease in AF / AE accuracy.

[0081] Furthermore, a check is performed to determine whether the accumulation timings of the LV display image signal Ch1 and the AF / AE evaluation value image signal Ch2 overlap. This is because the possibility of charge leakage from the AF / AE evaluation value image signal to the LV display image signal differs depending on whether the accumulation timings of the LV display image signal Ch1 and the AF / AE evaluation value image signal Ch2 overlap. If the accumulation timings of the two are different, there is no risk of charge leakage, and the process of separate accumulation can be omitted.

[0082] As described above, the imaging device of this embodiment can prevent a decrease in AF / AE accuracy while avoiding flickering and image quality degradation of the LV display image when performing AF, regardless of the LV display brightness. [Explanation of symbols]

[0083] 106 Image sensor 107 Imaging signal processing circuit 109 Overall Control Calculation Unit

Claims

1. A pixel section including a first pixel group and a second pixel group different from the first pixel group, A first output channel that outputs a display image signal obtained from the first pixel group, A second output channel that outputs an image signal for acquiring evaluation values ​​obtained from the second pixel group, A saturation determination means for determining the saturation state of the evaluation value acquisition image signal by comparing the brightness level of the display image signal or the evaluation value acquisition image signal with a predetermined threshold, When the saturation determination means determines that the image signal for acquiring the evaluation value is close to saturation, the control means determines the storage time and number of readouts of the image signal for acquiring the evaluation value in the second pixel group in order to avoid saturation of the image signal for acquiring the evaluation value, and controls the second pixel group to divide the image signal for acquiring the evaluation value into multiple portions for storage and readout during the blanking period when the display image signal is not read out. An imaging device characterized by having the following features.

2. Furthermore, the imaging apparatus according to claim 1 is characterized by having a synthesis means for synthesizing the evaluation value acquisition image signals read out in multiple segments from the second pixel group.

3. The imaging apparatus according to claim 2, characterized in that the control means determines the storage time and the number of readouts of the evaluation value acquisition image signal in the second pixel group so that the evaluation value acquisition image signal read out in multiple segments from the second pixel group is combined by the combining means to obtain a predetermined brightness.

4. The imaging apparatus according to any one of claims 1 to 3, characterized in that the control means determines the storage time and readout count of the evaluation value acquisition image signal in the second pixel group to avoid saturation of the evaluation value acquisition image signal when the storage timing of the display image signal in the first pixel group and the storage timing of the evaluation value acquisition image signal in the second pixel group overlap, and the saturation determination means determines that the evaluation value acquisition image signal is close to saturation.

Images