JP2013121138A - Imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging device which obtains a high-quality image signal by preventing black level depression caused by infra-red optical black (OB) float generated in an OB part and by appropriately clamping a change in the OB part generated by a dark current.SOLUTION: An imaging device has: a first photoelectric converter 108 for acquiring an imaging signal; a clamp section for clamping an optical black (OB) output from a shielded pixel in the imaging signal to a set level; and a second photoelectric converter 113 for detecting an infra-red object in the vicinity of an OB region of the first photoelectric converter 108. On the basis of an output of the second photoelectric converter 113, it is determined whether or not float caused by leakage of infra-red light in the OB of the first photoelectric converter 108 occurs. In a horizontal row determined that the infra-red OB float occurs, clamp is performed by using a preset output without performing clamp by using the OB output.

Description

  The present invention relates to an imaging apparatus including an imaging element.

  In general, an image sensor such as a CMOS sensor has an aperture pixel that outputs an image signal and a signal for obtaining an optical black level (hereinafter abbreviated as OB) that is an optical black level that is a reference of the image signal. A plurality of light-shielding pixels to be output are provided. Usually, the light-shielding pixels that output a signal for obtaining the OB level are provided in several pixels at the horizontal pixel number line at the top of the image sensor and at the head part or the last part of each horizontal line, or both. ing. Each shading pixel is called a vertical OB pixel and a horizontal OB pixel. In the signal processing circuit that processes the sensor output signal, the OB level is clamped to a predetermined level, and the subsequent signal processing such as conversion into a digital value is performed.

  An example of a signal processing circuit that clamps the OB level to a predetermined level will be described with reference to FIG. In FIG. 9, an AFE (Analog Front End) 202 performs processing of an analog signal from the image sensor 108. The AFE 202 mainly includes analog signal processing blocks such as a CDS circuit that performs correlated double sampling of a video signal and a variable gain control circuit (PGA circuit) that adjusts the amplitude level of the signal. The output of the analog signal processing block 012 is input to an adder / subtracter circuit 013 for adjusting the DC level, and then input to an A / D converter 014 for conversion into a digital value. The signal converted into a digital value is output to the outside and input to a feedback loop for OB level adjustment. In the feedback loop, first, the OB pixel output converted by the A / D converter 014 in the OB level calculation block 015 is averaged for the number of pixels in the preset OB area, and the OB level is calculated. The calculated OB level is compared with a preset OB target level, and the output value of the D / A converter 016 for DC level adjustment is set according to the comparison result. Then, the output of the D / A converter 016 is input to the addition / subtraction circuit 013 and is added / subtracted to / from the output of the analog signal processing block 012 to clamp the OB level to the OB target level.

  Here, consider the case of photographing a subject that contains a lot of infrared light. Light that enters the image sensor perpendicularly does not enter the OB pixel because the light shielding member is provided, but light that has a long reach within the image sensor, such as infrared light, is incident from a pixel that is not shielded. Is reflected by the back surface of the image sensor until it disappears due to photoelectric conversion, and the possibility of reaching the OB pixel increases.

  FIG. 10 shows an OB output when a subject including a large amount of infrared light is photographed. As shown in FIG. 10, the OB output when photographing a subject 61 containing a lot of infrared light peaks at the output level of the OB pixel closest to the subject, and gradually decreases to the normal OB level as the distance increases. . This is called infrared OB floating. In this way, when the output signal of the image sensor that has captured a subject that contains a lot of infrared light is clamped, the OB level is constant, but the image output before and after the subject that contains a lot of infrared light sinks in the black direction, The image deteriorates. This is called black sun. There are the following methods as countermeasures against black sinking due to such infrared OB floating. That is, the infrared OB float, which is a gentle change in the OB pixel output, is discriminated for each horizontal line, and when the infrared OB float is detected, clamping is performed based on the already held differential output, so A method for preventing black sink has been devised (see, for example, Patent Document 1).

JP 2006-157242 A

  However, in the technique disclosed in Patent Document 1 described above, the same processing is uniformly applied when a gentle change occurs in the OB portion. As a factor that causes a gentle change in the OB portion, dark current unevenness due to a temperature rise can be considered besides the infrared OB floating. Regarding the change in the OB portion caused by the dark current unevenness, the same unevenness also occurs in the effective pixel region. Therefore, it is desirable to clamp using the output of the OB portion. However, the technique disclosed in Patent Document 1 has a problem that it cannot be determined whether the change in the OB portion is caused by floating infrared OB or other factors.

  The present invention is an image pickup apparatus that can prevent black sink due to infrared OB floating, and can obtain a high-quality image signal by appropriately clamping the change of the OB portion caused by dark current. The purpose is to provide.

  The present invention has been made to solve the above-described problems, and is provided independently of the first photoelectric conversion means provided with a plurality of aperture pixels and light-shielding pixels, and the first photoelectric conversion means. , Second photoelectric conversion means for detecting infrared light incident on the first photoelectric conversion means, clamp means for clamping the output signal of the light-shielded pixel to a predetermined level, and output of the second photoelectric conversion means A determination unit that determines whether a signal level variation due to the infrared light has occurred in an output signal of the light-shielded pixel of the first photoelectric conversion unit based on the signal; and an output of the light-shielded pixel by the determination unit Control means for controlling the clamping means so as not to change the clamping level based on the output signal of the light-shielding pixel when it is determined that a signal level fluctuation due to the infrared light has occurred in the signal; Characterized by comprising.

  In addition, a first photoelectric conversion unit provided with a plurality of aperture pixel regions and a plurality of light-shielding pixel regions, and an infrared ray provided independently of the first photoelectric conversion unit and incident on the first photoelectric conversion unit Second photoelectric conversion means for detecting light, clamping means for clamping the output signal of the light-shielded pixel to a predetermined level, and light shielding of the first photoelectric conversion means based on the output signal of the second photoelectric conversion means A first determination unit that determines whether or not a signal level variation due to the infrared light has occurred in an output signal of a pixel, and a signal level variation due to the infrared light is generated by the first determination unit. A second determination for determining whether or not a signal level fluctuation due to the infrared light actually occurs based on an output signal of a light-shielded pixel of the first photoelectric conversion means Means and the second judgment hand Control means for controlling the clamping means so as not to change the clamping level based on the output signal of the light-shielding pixel when it is determined that the fluctuation of the signal level due to the infrared light has actually occurred. It is provided with.

  According to the present invention, it is possible to prevent black sink due to floating of infrared OB, and to obtain a high-quality image signal by appropriately clamping the change of the OB portion caused by dark current. Become.

It is sectional drawing of the digital single-lens reflex camera in Example 1 of this invention. It is a figure which shows the spectral sensitivity of the photometric sensor for light source detection in Example 1 of this invention. It is a figure which shows the photometry area of the photometry sensor for light source detection in Example 1 of this invention. It is a block diagram of the digital single-lens reflex camera in Example 1 of the present invention. It is a flowchart for demonstrating the infrared OB floating determination operation | movement in Example 1 of this invention. It is a block diagram for demonstrating the OB clamp operation | movement in Example 1 of this invention. It is a flowchart for demonstrating the OB clamp operation | movement in Example 1 of this invention. It is a block diagram for demonstrating the OB clamp operation | movement in Example 2 of this invention. It is a block diagram for demonstrating the conventional clamp operation | movement. It is an image figure for demonstrating infrared OB floating.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a cross-sectional view of the digital single-lens reflex camera according to the first embodiment. In FIG. 1, a photographing lens 102 is attached to the front surface of a camera body 101 that is an imaging device. The photographing lens 102 can be exchanged, and the camera body 101 and the photographing lens 102 are electrically connected via a mount contact group 112. Further, the photographing lens 102 has an aperture 110 so that the amount of light taken into the camera can be adjusted.

  The main mirror 103 is a half mirror, and is obliquely arranged on the photographing optical path in the finder observation state, and reflects the photographing light flux from the photographing lens 102 to the finder optical system, while the transmitted light is AF through the sub mirror 104. The light enters the unit 105. In the photographing state, the evacuation is taken out of the photographing optical path.

  The AF unit 105 is a phase difference detection type AF sensor, and since focus detection by the phase difference method is a known technique, specific control is omitted here. Briefly, the in-focus state (defocus amount) of the photographic lens 102 is detected by forming a secondary imaging surface of the photographic lens 102 on the focus detection line sensor and obtaining a phase difference signal. Based on the detection result, a focusing lens (not shown) is driven to perform focus detection.

  The image sensor 108 serving as the first photoelectric conversion means receives reflected light (subject image) from the subject, photoelectrically converts it into an electrical signal (video signal), and outputs it. As described in the background art, the imaging element 108 is provided with a plurality of pixels each having an aperture pixel that outputs an imaging signal and a light-shielding pixel that outputs a signal for obtaining an OB level as a reference of the imaging signal. Yes. A low-pass filter 106 and a focal plane shutter 107 are provided on the front surface of the image sensor 108.

  Further, a focusing plate 109 is disposed on the planned imaging plane of the taking lens 102 constituting the finder optical system, and the photographer observes the focusing plate 109 from the eyepiece 114 via the finder optical path changing pentaprism 115. , You can check the shooting screen. A photometric sensor 111 for AE and a photometric sensor 113 for light source detection, which is a second photoelectric conversion means, are photometric sensors for performing photometry, respectively. The light source detection photometric sensor 113 has spectral sensitivity characteristics different from those of the AE photometry sensor 111, and the type of the light source is determined using the output of the light source detection photometry sensor 113 and the output of the AE photometry sensor. The light source information obtained by the type discrimination of the light source is used for correcting the focus position due to the difference in the light source. Here, since the light source detection method and the focus position correction using the photometric sensors having different spectral characteristics are known techniques, a detailed description is omitted.

  In this embodiment, based on the output signal of the light source detection photometric sensor 113 provided independently of the image sensor 108, an infrared subject (subject that contains a lot of infrared light) in the shooting screen of the image sensor 108 is used. Is used for clamp control. That is, infrared light incident on the image sensor 108 is detected. Details of infrared object detection and clamp control will be described later.

  Next, the light source detection photometric sensor 113 will be described with reference to FIGS. FIG. 2 is a diagram showing the spectral sensitivity characteristics of the light source detection photometric sensor 113. The light source detection photometric sensor 113 includes an optical filter for achieving desired spectral sensitivity characteristics. That is, only the infrared light that affects the image sensor for image capture needs to be detected, so the spectral sensitivity characteristics of the photometric sensor for light source detection are set according to the spectral sensitivity characteristics on the infrared side of the image sensor. Is done. As shown in FIG. 2, the spectral sensitivity characteristic of the light source detection photometric sensor 113 has a spectral sensitivity characteristic capable of capturing light having a wavelength in the vicinity of 600 nm to 800 nm in the infrared region.

  FIG. 3 is a diagram showing a photometric area of the photometric sensor 113 for light source detection. In this embodiment, a total of 36 areas can be photometrically divided into 6 parts in the vertical direction and 6 parts in the horizontal direction. Here, the photometric range of the photometric sensor 113 for detecting the light source can be measured in an area substantially coincident with the imaging area of the imaging device for image capturing shown in FIG.

  Next, the configuration of the camera of this embodiment will be described with reference to the block diagram of FIG. In addition, the same number is attached | subjected about the same member as another drawing. In FIG. 4, the light incident from the taking lens 102 passes through the stop 110 and reaches the mirror box 201. The mirror box 201 includes the main mirror 103 and the sub mirror 104 described above, and divides incident light into transmitted light and reflected light. The divided transmitted light and reflected light can be switched between a state in which the transmitted light and the reflected light are respectively guided to the AF unit 105 and the AE photometric sensor 111 and a state in which the incident light is directly guided to the image sensor 108.

  The taking lens 102 is driven by a lens driving unit 212 for focus adjustment. The diaphragm 110 is driven by the diaphragm driver 211, and the mirror box 201 is driven by the mirror driver 210. The shutter 107 is driven by a shutter driving unit 209.

  The CPU 205 controls each part of the camera body. For example, the CPU 205 controls a DSP (Digital Signal Processor) 204, a TG (Timing generator) 203, and a camera function using each unit (not shown). Further, the CPU 205 determines the aperture value and shutter speed at the time of exposure based on the photometric information from the AE photometric sensor 111 and controls the shutter drive unit 209 and the aperture drive unit 211. Further, based on the outputs of the light source detection photometric sensor 113 and the AE photometry sensor 111, a correction value for the focus position due to the difference in the light source is calculated. Further, based on the signal from the AF unit 105 and the correction value of the focus position due to the difference in the light source, the lens driving amount necessary for focusing is determined, and the lens driving unit 212 is controlled.

  In this embodiment, at the time of metering by the light source detection metering sensor 113, the metering value of the metering area near the horizontal OB region provided in the image sensor 108 is recorded, and the infrared OB floating determination is performed using the output value. carry out.

  At the time of exposure, the mirror drive unit 210 retracts the main mirror 103 and the sub mirror 104 from the photographing optical path. Then, the shutter 107 is driven by the shutter driving unit 209, and exposure is performed for a predetermined exposure time, whereby the light flux from the photographing lens 102 is imaged on the image sensor 108. Here, the image sensor 108 is composed of a photoelectric conversion element such as a CMOS or a CCD.

  An AFE (Analog Front End) 202 receives an image signal from the image sensor 108 and performs predetermined analog processing on the received image signal. The predetermined analog processing includes amplification processing, analog-digital conversion processing (A / D conversion processing), and OB clamp processing. The AFE 202 outputs the processed image signal (digital signal) to the DSP 204.

  The TG 203 is controlled by the CPU 205 and supplies a clock signal and a control signal to the image sensor 108, the AFE 202, and the DSP 204. Then, a control signal is supplied to the AFE 202 in accordance with the determination result of the infrared OB floating to change the control of the OB clamping process. Details thereof will be described later.

  The ROM 213 stores a control program for the image pickup apparatus 101, a correction table, and the like. The RAM 214 temporarily stores image data and correction data processed by the DSP 204. The RAM 214 can be accessed at a higher speed than the ROM 213. The recording medium 207 is connected to the DSP 204 via a connector (not shown) and stores captured image data. The recording medium 207 is, for example, a compact flash (registered trademark) card (hereinafter CF).

  The display unit 206 receives image data from the DSP 204, converts the received image data into a display signal, and displays an image. The release switch 208 is a two-stage push-in switch having a half-pressed state and a fully-pressed state. When the release switch 208 is pressed halfway, preparatory operations such as AE, AF, and light source detection are performed. When the release switch 208 is fully pressed, the image sensor 108 is exposed and shooting processing is performed. Hereinafter, the half-pressed state is referred to as a state where SW1 is turned on, and the fully-pressed state is referred to as a state where SW2 is turned on.

  Next, the infrared OB floating determination operation of the camera system in the present embodiment will be described with reference to the flowchart of FIG. When the release switch 208 shown in FIG. 4 is pressed halfway and SW1 is turned on, AF operation and AE operation are performed, and then an infrared OB floating determination operation using the light source detection photometric sensor 113 is started.

  In step S <b> 701, photometry is performed by the light source detection photometric sensor 113, and the photometric values of the respective areas shown in FIG. 3 are stored in the RAM 214. In step S702, the count value i of the counter is set to the initial value 1. Thereafter, the count value of the counter is increased, and it is determined whether or not the photometric value is greater than or equal to a predetermined value for the regions A11 to A61 in the vicinity of the horizontal OB. In step S703, when the photometric value of the area Ai1 of the light source detection photometric sensor is equal to or greater than a predetermined value, the horizontal OB pixel corresponding to the vicinity of the area Ai1 floats in the infrared OB, that is, the output signal of the horizontal OB pixel that is a light-shielded pixel. It is determined that a change in signal level due to infrared light has occurred, and the process proceeds to step S704. In step S704, the area information P is stored in the RAM 214. Here, the region information stored in the RAM 214 is the row information of the horizontal OB of the image sensor 108 corresponding to the region Ai1 of the light source detection photometric sensor. For example, it is stored as the start line Ri_start and the end line Ri_end. Here, Ri_start and Ri_end need not exactly match the region Ai1. For example, it is possible to set a line that surely includes Ai1 by setting with a margin of about 50 lines.

  Next, in step S705, it is determined whether or not the count value i of the counter is equal to 6. That is, it is determined whether infrared OB floating determination has been performed for all regions A11 to A61 in the vicinity of the horizontal OB. If the count value is equal to 6, the infrared OB floating determination flow is terminated. If the count value is not equal to 6, in step S706, 1 is added to the count value of the counter, the process proceeds to step S703, and the infrared OB floating determination process is continued.

  The above is the flow of the infrared OB floating determination, and it is determined whether or not there is an infrared subject that causes the infrared OB floating using the output value of the light source detection photometric sensor near the horizontal OB. This infrared OB floating determination flow is performed under the control of the CPU 205.

  Next, the OB clamping operation at the time of detecting the infrared subject in the present embodiment will be described with reference to the flowcharts of FIGS.

  In FIG. 6, an analog signal processing block 012 first receives an image signal from the image sensor 108 and mainly performs correlated double sampling, or a variable gain control circuit (PGA circuit) that adjusts the amplitude level of the signal. Consists of. The output of the analog signal processing block 012 is input to an adder / subtractor circuit 013 for adjusting the OB level, and then input to an A / D converter 014 for conversion into a digital value.

  The signal converted into the digital value is output to the outside and input to the feedback loop for OB level adjustment. In the feedback loop, first, in the OB level calculation block 015, the OB level converted by the A / D converter 014 is compared with the target OB level setting value which is the clamp level. Then, the comparison result is input as a difference output to a D / A converter 016 that is a holding unit for setting an adjustment value via a switch 018. The output of the D / A converter 016 is input to the adder / subtracter circuit 013, and the OB level is clamped to the set value which is the clamp level by adding / subtracting to the output of the analog signal processing block 012.

  Here, the difference from the clamping operation by the signal processing circuit of FIG. 9 is that the switch 018 is opened and closed based on the result of the infrared OB floating determination unit 017. The infrared OB floating determination unit 017 is included in the CPU of FIG. FIG. 7 is a flowchart for explaining the OB clamping operation in the first embodiment. Hereinafter, a description will be given with reference to the flowchart of FIG.

  When the horizontal OB clamping operation is started, in step S601, it is determined whether or not the row in which the infrared OB float is generated in the row during the clamping operation. Specifically, it is included in the region information (Ri_start to Ri_end) of the horizontal OB pixel region that is determined and stored as the infrared OB floating when the infrared OB floating determination is performed when the horizontal OB pixel is clamped. It is determined whether it is a row to be processed.

  If it is determined that the line is in the region where the infrared OB float occurs, the process proceeds to step S603, and the infrared OB float determination unit 017 in the CPU 205 outputs a signal for turning off the switch 018. Then, the switch 018 of FIG. 6 is shut off and control is performed so as not to change the clamp level. In this case, the value held in the D / A converter 016 serving as a holding unit is output to the adder / subtracter circuit 013 as a clamp level. A signal for turning off the switch 018 is supplied from the CPU 205 via the TG 203.

  If it is determined in step S601 that the line is not in the region where the infrared OB float occurs, the process proceeds to step S602, and the clamp is performed based on the calculation result of the OB level calculation block 015 in FIG. To be implemented. When the clamping operation in step S602 or step S604 is completed, the process proceeds to step S604, where it is determined whether or not the OB clamping operation has been completed for all rows. If it is determined that the process has not been completed, the process returns to step S601 to start the OB clamping operation for the next line. If it is determined that all the lines have been completed, the OB clamping process is terminated.

  By controlling as described above, it is possible to prevent the malfunction of the clamp due to the infrared OB floating and to maintain the quality of the image signal. In this embodiment, the example in which the photometric sensor used for detecting the AF light source is used as the second photoelectric conversion means for detecting the infrared OB float has been described. However, other photoelectric conversion elements are used. It is good also as a structure.

  Next, FIG. 8 is a block diagram for explaining the OB clamping operation in the second embodiment. The OB clamping operation in the second embodiment of the present invention will be described using the block diagram of FIG. Since the configuration other than the OB clamping operation is the same as that of the first embodiment described with reference to FIGS. 1 to 5, the description thereof will be omitted, and only the OB clamping operation different from that of the first embodiment will be described.

  In FIG. 8, an analog signal processing block 012 first receives an image signal from the image sensor 108 and mainly performs correlated double sampling, and a variable gain control circuit (PGA circuit) that adjusts the amplitude level of the signal. Consists of. The output of the analog signal processing block 012 is input to an adder / subtractor circuit 013 for adjusting the OB level, and then input to an A / D converter 014 for conversion into a digital value.

  The signal converted into the digital value is output to the outside and input to the feedback loop for OB level adjustment. In the feedback loop, first, in the OB level calculation block 015, the OB level converted by the A / D converter 014 is compared with the target OB level setting value which is the clamp level. Then, the comparison result is input as a difference output to a D / A converter 016 which is an adjustment value setting holding unit via a switch 025. The output of the D / A converter 016 is input to the adder / subtracter circuit 013, and the OB level is clamped to the set value which is the clamp level by adding / subtracting to the output of the analog signal processing block 012. Here, the difference from the clamping operation by the signal processing circuit of FIG. 6 is that the switch 021 is opened / closed based on the determination result of the infrared OB floating determination unit 017 and the determination result of the OB floating amount determination unit 024. Thus, the switch 025 is opened and closed.

  When the infrared OB floating determination is not performed, a signal for controlling the switch 021 to be turned off is transmitted from the infrared OB floating determination unit 017. In this case, a control signal is sent from the OB floating determination unit 024 so that the switch 025 is turned on, and a normal OB clamping operation is performed.

  When the infrared OB floating determination is made, a signal for controlling the switch 021 to be turned on is sent from the infrared OB floating determination unit 017, and the output of the A / D converter 014 is output. This is input to the OB floating determination unit 024.

  The OB floating determination unit 024 determines whether or not infrared OB floating actually occurs based on the output signal of the horizontal OB pixel. For example, the comparator 022 and the counter 023 are incorporated, and the comparator 022 compares the output signal level of each horizontal OB pixel with a comparison value set for each row in which the OB clamping is performed. Then, the counter 023 counts the number of horizontal OB pixels that output an output level larger than the comparison value, and when the counted number of horizontal OB pixels is equal to or greater than a predetermined value, the infrared OB float is actually generated in that row. It is determined that it has occurred.

  When the OB float amount determination unit 024 determines that infrared OB float has occurred, a signal for turning off the switch 025 is output to shut off the switch 025 so that the clamp level is not changed. To control. In this case, the value held in the D / A converter 016 serving as a holding unit is output to the adder / subtractor circuit 013 as a clamp level, and the clamp operation using the output of the horizontal OB pixel in this row is not performed. On the other hand, when the OB float amount determination unit 024 determines that the infrared OB float of a predetermined amount or more has not occurred, the switch 025 is turned on, and the normal result is based on the calculation result of the OB level calculation block 015. OB clamping operation is performed.

  In the second embodiment described above, the infrared OB floating determination is performed by the light source detection photometric sensor 113 which is the second photoelectric conversion means, and it is further determined that the infrared OB floating may occur. For a row, it is configured to determine whether or not an OB level float has actually occurred. With such a configuration, it is possible to further improve the detection accuracy of the infrared OB floating, to prevent the malfunction of the clamp due to the infrared OB floating, and to maintain the quality of the image signal.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

(Other examples)
The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, or the like) of the system or apparatus reads the program. It is a process to be executed.

012 Analog signal processing block 013 Addition / subtraction circuit 014 A / D converter 015 OB level calculation unit 016 D / A converter 017 Infrared OB floating determination unit 018 Switch 108 Imaging element 202 AFE

Claims (4)

First photoelectric conversion means provided with a plurality of aperture pixels and a plurality of light-shielding pixels,
A second photoelectric conversion means that is provided independently of the first photoelectric conversion means and detects infrared light incident on the first photoelectric conversion means;
Clamping means for clamping the output signal of the light-shielding pixel to a predetermined level;
A determination unit that determines whether or not a signal level variation due to the infrared light occurs in the output signal of the light-shielded pixel of the first photoelectric conversion unit based on the output signal of the second photoelectric conversion unit;
When it is determined by the determination means that a signal level variation due to the infrared light has occurred in the output signal of the light-shielded pixel, the clamp level is not changed based on the output signal of the light-shielded pixel. Control means for controlling the clamping means;
An imaging apparatus comprising: A first photoelectric conversion means provided with a plurality of aperture pixel areas and a plurality of light-shielding pixel areas,
A second photoelectric conversion means that is provided independently of the first photoelectric conversion means and detects infrared light incident on the first photoelectric conversion means;
Clamping means for clamping the output signal of the light-shielding pixel to a predetermined level;
First determination for determining whether a signal level variation due to the infrared light occurs in the output signal of the light-shielded pixel of the first photoelectric conversion unit based on the output signal of the second photoelectric conversion unit Means,
When it is determined by the first determination means that a change in signal level due to the infrared light has occurred, the signal due to the infrared light based on the output signal of the light-shielded pixel of the first photoelectric conversion means A second determination means for determining whether or not a level fluctuation has actually occurred;
The clamp means so as not to change the clamp level based on the output signal of the light-shielded pixel when it is determined by the second determination means that the fluctuation of the signal level due to the infrared light has actually occurred. Control means for controlling
An imaging apparatus comprising:   The second determination unit includes a comparison unit that compares a signal level of an output signal of the light-shielded pixel with a predetermined value, and a counter that counts the number of light-shielded pixels that output a higher signal level than the comparison unit. And determining that the fluctuation of the signal level due to the infrared light actually occurs when the number of light-shielding pixels counted by the counter is equal to or greater than a predetermined value. The imaging device described.   The imaging apparatus according to claim 1, wherein the second photoelectric conversion unit is a photometric sensor for detecting a light source.

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