JP2015029195A - Imaging device and control method for imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and reliably reduce noise recorded in a photographed image.SOLUTION: Timing of starting to output a reference voltage Vslop in a D-phase period is adjusted so that concerning a period of noise, a temporal difference ΔT between timing of P-phase output and timing of D-phase output becomes an integer multiple of the inverse of a noise frequency f.

Description

  The present invention relates to an imaging apparatus and an imaging apparatus control method, and is particularly suitable for use in capturing an image.

In recent years, electronic devices such as mobile phones and PDAs are increasing in number having a photographing function in addition to the original functions of the electronic device. Such an electronic device with a photographing function is equipped with a small imaging device called a camera module. In addition, downsizing of an imaging apparatus such as a digital camera or a video camera whose main function is an imaging function is still in progress.
A small imaging device such as a camera module is an image obtained by photoelectrically converting an optical system composed of a plurality of optical components, an actuator for moving the optical components for zoom adjustment, etc., and a subject image formed by the optical system. An image sensor for generating a signal. Typical image sensors include image sensors such as CCD sensors and CMOS sensors.

  Conventionally, when a PWM driving stepping motor is used as an actuator for driving a lens, there is a problem that noise is added to an image signal output from an image sensor. In particular, when a CMOS sensor is used as the image sensor, noise (electromagnetic waves) generated from the stepping motor may spatially affect the output of the CMOS sensor when the physical distance between the CMOS sensor and the stepping motor is short. This is due to an operation peculiar to a CMOS sensor in which charges accumulated in the photodiode are converted into a voltage for each pixel and a signal is read out. In order not to generate noise, a fundamental measure is to increase the physical distance between the CMOS sensor and the stepping motor.

However, in order to meet the demand for miniaturization in camera modules and small imaging devices, it is necessary to reduce the distance between a stepping motor that drives a driving object such as an optical component and a CMOS sensor that is susceptible to noise from the stepping motor. There are many cases where it cannot be obtained.
Therefore, the techniques of Patent Documents 1 to 3 have been proposed.
In Patent Document 1, by changing the PWM drive frequency of the actuator at the timing of reading out a charge signal from the image sensor, the magnetic force generated by driving the actuator is prevented from affecting the output signal of the image sensor.
In Patent Document 2, when a charge signal is read from an image sensor, the time difference between the read timing of the noise component and the read timing of the signal component is set to be an integral multiple of the reciprocal of the PWM drive frequency f of the actuator.
In Patent Document 3, first, information indicating the correspondence between the frequency of noise generated in accordance with the operation of the power supply circuit and the temperature is stored in a memory. Thereafter, the noise frequency is estimated based on the detection result of the temperature detection unit and the information indicating the correspondence relationship between the noise frequency and the temperature, and the drive frequency of the drive signal is changed according to the estimated noise frequency. .

JP 2012-28841 A JP 2010-50636 A JP 2010-141799 A

  However, in the technique described in Patent Document 1, if only the PWM drive frequency is changed, there is a possibility that the desired operation may be hindered due to oscillation of the actuator. For this reason, when the PWM drive frequency is changed, the servo characteristics of the actuator must be changed at the same time. Also, when setting different PWM drive frequencies depending on the drive mode of the image sensor, it is necessary to know in advance the servo characteristics corresponding to each PWM drive frequency. For this reason, a great examination load is generated in the development process of the imaging apparatus.

Japanese Patent Laid-Open No. 2004-228561 discloses a countermeasure for a case where the operating frequency of a noise generation source varies from individual to individual, such as switching noise of a power supply circuit, or the operating frequency varies due to factors such as temperature. Absent. Further, Patent Document 2 does not disclose a method in the case where there are a plurality of lens driving units each having a plurality of different driving frequencies. In addition, there is no disclosure of a method in which one lens driving unit is driven at a different driving frequency depending on time.
In addition, when performing single slope integration type AD conversion used in a column AD type image sensor that is generally used, if the gain setting is changed, the slope of the ramp waveform serving as the reference signal changes. For this reason, the timing for AD conversion of the image signal changes for each gain setting. However, Patent Document 2 does not disclose the correspondence of the configuration of the column AD type image sensor, and cannot cope with the gain change.

  In the technique described in Patent Document 3, it is necessary to measure the temperature characteristic of the noise frequency in advance and store it in the memory. The temperature dependence of the noise frequency varies from individual to individual, and the accuracy of temperature detection by the temperature sensor also varies from individual to individual. For this reason, it is not realistic to store information covering all of them in the memory.

  The present invention has been made in view of the above problems, and an object thereof is to easily and reliably reduce noise recorded in a captured image.

According to a first aspect of the imaging apparatus of the present invention, a pixel unit configured by arranging a plurality of pixels each having a photoelectric conversion unit that photoelectrically converts incident light and arranged in a matrix, and the pixel, Reading means for reading a reset signal that is a signal when the potential is reset and reading of an accumulation signal that is a signal accumulated in the pixel, and timing control means for controlling the timing of the reading by the reading means An imaging device that generates image data based on a signal read by the reading unit, the frequency analyzing unit performing frequency analysis on the image data, and the frequency Based on the result of the frequency analysis by the analysis means, the switching operation frequency of the circuit including the transistor that performs the switching operation is calculated. Output frequency deriving means, signal readout timing when resetting the potential of the pixel so as to correspond to the switching operation frequency derived by the frequency deriving means, and readout of the signal accumulated in the pixel Control means for determining an interval with respect to timing.
According to a second aspect of the imaging apparatus of the present invention, a pixel unit configured by a plurality of pixels each having photoelectric conversion means for photoelectrically converting incident light is arranged in a matrix, and the pixel includes: Reading means for reading a reset signal that is a signal when the potential is reset and reading of an accumulation signal that is a signal accumulated in the pixel, and timing control means for controlling the timing of the reading by the reading means And a plurality of lens driving means for driving the lenses at different driving frequencies, respectively, and generating image data based on a signal read by the reading means And a signal readout timing when the pixel potential is reset so as to correspond to the least common multiple of the reciprocal of the different driving frequencies. And having a grayed, and control means for determining the distance between the timing of the read of the stored signal to the pixel.
According to a third aspect of the imaging apparatus of the present invention, a pixel unit configured by arranging a plurality of pixels each having photoelectric conversion means for photoelectrically converting incident light and arranged in a matrix, and the pixel, Reading means for reading a reset signal that is a signal when the potential is reset and reading of an accumulation signal that is a signal accumulated in the pixel, and timing control means for controlling the timing of the reading by the reading means And an image pickup device that generates image data based on a signal read by the reading unit, wherein the lens driving frequency is changed over time, and the lens Lens driving means for driving the lens, determination means for determining information relating to the current driving frequency of the lens, and before the determination by the determination means Control means for determining an interval between a signal readout timing when the potential of the pixel is reset and a readout timing of the signal accumulated in the pixel so as to correspond to the driving frequency of the lens obtained from information It is characterized by having.
According to a fourth aspect of the imaging apparatus of the present invention, there is provided a pixel portion configured by arranging a plurality of pixels each having photoelectric conversion means for photoelectrically converting incident light in a matrix, and from the pixels, Reading means for reading a reset signal that is a signal when the potential is reset and reading of an accumulation signal that is a signal accumulated in the pixel, and timing control means for controlling the timing of the reading by the reading means And an image pickup apparatus that generates image data based on a signal read by the reading unit, and determines the read timing controlled by the timing control unit An analog-to-digital signal that is converted from the analog signal output from the pixel into a digital signal; The AD conversion means starts to output the reference signal and a comparison means for comparing the analog signal output from the pixel with a reference signal whose value changes with time. Count means for performing a counting operation until the value of the analog signal and the value of the reference signal become the same, and the control means is configured to determine a value per unit time of the reference signal. A gain in the AD conversion is set by changing a change amount. Based on the set gain, a timing at which the value of the analog reset signal and the value of the reference signal become the same, and the analog The interval between the value of the accumulated signal and the timing at which the value of the reference signal becomes the same is determined.

  According to the present invention, it is an object to easily and reliably reduce noise recorded in a captured image.

It is a figure which shows the 1st example of a structure of an imaging device. It is a figure which shows the pixel circuit of a CMOS image sensor. It is a figure which shows the structure of the solid-state image sensor which mounts column parallel type ADC. It is a figure which shows the pixel and ADC of 1 row contained in a pixel part. It is a figure which shows an output waveform when noise cannot be removed. It is a figure which shows an output waveform in case noise can be removed. It is a flowchart which shows the 1st example of the method of removing a magnetic noise. It is a figure which shows the 2nd example of a structure of an imaging device. It is a flowchart which shows the 2nd example of the method of removing a magnetic noise. It is a figure which shows the time transition of the time difference of the time transition of a noise frequency, and the timing of a P-phase output and D-phase output timing. It is a flowchart which shows the 3rd example of the method of removing a magnetic noise. 5 is a flowchart illustrating a method for deriving a switching operating frequency. It is a figure which shows the frequency where a peak appears by discrete Fourier transform. It is a figure which shows the structure of a solid-state image sensor and a control part. It is a figure which shows an example of the output waveform of DAC. It is a figure which shows the output timing of the reference voltage in case noise cannot be removed. It is a figure which shows the output timing of the reference voltage in case noise can be removed. It is a flowchart which shows the method of changing the output timing of a reference voltage. It is a figure which shows a picked-up image notionally. It is a figure which shows the histogram of the luminance value of a picked-up image, and the relationship between a luminance value and the S / N ratio of a pixel signal.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
First, a first embodiment of the present invention will be described.
FIG. 1 is a diagram illustrating an example of the configuration of the imaging apparatus according to the present embodiment. As an example of the imaging apparatus, there are a digital still camera, a digital video camera, and the like.
In FIG. 1, the imaging apparatus includes an imaging optical system 101, an imaging element unit 107, a lens driving unit 114, an imaging optical system sensor (position sensor) 113, and a signal processing unit 111. In addition, the imaging apparatus includes a display unit 119, a recording / reproducing unit 120, a motion detection sensor 118, and a control unit 115.
The imaging optical system 101 includes a lens 102 that changes magnification, a focus lens 104 that performs focusing, a correction lens driving unit 105 that moves the position of an optical image formed on the imaging surface of the solid-state imaging device, and an imaging surface. . Further, the imaging optical system 101 includes a mechanical shutter 106 that mechanically adjusts the exposure amount on the imaging surface of the solid-state imaging device, and a diaphragm mechanism 103 that adjusts the light amount of an optical image formed on the imaging surface of the solid-state imaging device. And.

  For example, the correction lens driving unit 105 displaces the correction lens 105 a provided so that the optical axis coincides with the optical axis of the imaging optical system 101, and the correction lens 105 a in a direction orthogonal to the optical axis of the imaging optical system 101. And an actuator 105b to be operated. The correction lens driving unit 105 moves the correction lens 105a in a direction orthogonal to the optical axis of the imaging optical system 101 by the actuator 105b, and the relative positions of the lens 101, the focus lens 104, and the solid-state imaging device. The relationship is displaced with respect to the optical axis. Specifically, the correction lens driving unit 105 displaces the inclination angle of the output end plate with respect to the incident end plate, for example, and sets the position of the optical image formed on the image pickup surface of the solid-state image pickup device on the image pickup surface of the solid-state image pickup device. Move with.

The actuator 105b that drives the correction lens 105a or the variable apex angle prism unit mainly includes a magnet and a coil. The actuator 105b drives the correction lens 105a by passing an electric current through the coil and generating an electromagnetic force with respect to the coil by a magnetic field generated from the coil. Electromagnetism generated at this time causes horizontal streak noise in the image to be taken.
The lens driving unit 114 includes, for example, a stepping motor, and drives the lens 101, the focus lens 104, and the actuator 105b of the correction lens driving unit 105 based on a lens control signal from the control unit 115 described later. The lens driving unit 114 drives the diaphragm mechanism 103 based on the diaphragm control signal from the control unit 115. For example, a PWM (Pulse Width Modulation) method can be used as a driving method when driving the lens 101, the focus lens 104, and the correction lens driving unit 105. The control by the PWM method is a pulse control method in which the amplitude of the drive voltage is made constant and the time width of the pulse changing in a rectangular wave shape is changed within a fixed period.

In this embodiment, the focus lens 104 and the correction lens driving unit 105 are both driven by the PWM method. However, the driving method of the focus lens 104 and the correction lens driving unit 105 is described here. It is not limited. Further, in the present embodiment, the description will focus on the case where the influence of noise generated by the lens driving unit 114 that generates magnetism, such as a coil, on the image is suppressed. However, in addition to the coil, for example, noise having periodicity generated from a power system DD converter, a liquid crystal panel, or the like can be avoided by the same method. The reason why noise is easily affected in the case of PWM drive is that the change in magnetic flux is maximized in the rise or fall operation of the voltage in PWM drive, and as a result, the fluctuation of the induced voltage due to electromagnetic induction becomes large. Because. The position sensor 113 detects the lens position of the lens 101 and the focus lens 104, the displacement state of the correction lens driving unit 105 (the displacement position and correction angle of the correction lens 105a), and the set position of the diaphragm mechanism 103, and outputs a position signal. This is supplied to the control unit 115.
The mechanical shutter driver 112 opens and closes the mechanical shutter 106 based on a shutter open / close signal sent from the control unit 115 in order to obtain an appropriate exposure amount at the time of still image shooting.

The imaging element unit 107 includes a solid-state imaging element, and converts an optical image formed on the imaging surface of the solid-state imaging element by the imaging optical system 101 into an electrical signal. The image sensor unit 107 generates various drive pulses in order to output an electrical signal corresponding to the image data captured by the solid-state image sensor. The image sensor unit 107 also generates an electronic shutter pulse that controls the charge accumulation time of the solid-state image sensor.
The image sensor unit 107 performs CDS (Correlated Double Sampling) processing on the electrical signal (image signal) output from the solid-state image sensor to remove noise. In addition, the image sensor unit 107 performs gain control processing (AGC (Automatic Gain Control)) processing for setting the electrical signal output from the solid-state image sensor to a desired signal level. In this method, the signal level (reset level) immediately before sampling is read once and stored, then the signal level after sampling is read and subtracted to remove noise. Furthermore, the image sensor unit 107 converts an analog electric signal subjected to noise removal processing and gain control into a digital image signal and outputs the digital image signal to the signal processing unit 111.

  The signal processing unit 111 performs camera signal processing such as resolution conversion processing and compression / decompression processing. Specifically, for the image signal supplied from the image sensor unit 107, a defect correction process for correcting a signal of a defective pixel in the solid-state image sensor, a shading correction process for correcting a decrease in the amount of light around the lens, and a white Processing such as balance adjustment and luminance correction is performed. In the resolution conversion process, the signal processing unit 111 converts the image signal that has been subjected to camera signal processing or the image signal that has been subjected to decompression decoding into a predetermined resolution. In the compression / decompression process, the signal processing unit 111 compresses and encodes the image signal after the camera signal process and the image signal subjected to the resolution conversion process to generate, for example, a JPEG encoded signal. Further, the signal processing unit 111 decompresses and decodes the JPEG encoded signal in the compression / decompression process. In the compression / decompression process, a still image signal may be compressed and encoded by a method different from the JPEG method.

The control unit 115 controls each component of the imaging device. The control unit 115 sends a control signal for driving the actuator 105 b of the correction lens driving unit 105 to the lens driving unit 114 based on the motion detected by the motion detection sensor 118. Based on this control signal, the lens driving unit 114 drives the actuator 105b to move the correction lens 105a in a direction orthogonal to the optical axis of the imaging optical system 101, thereby correcting image blur due to camera shake. Can do. In the present embodiment, the control unit 115 acquires the driving frequency from the lens driving unit 114 and temporarily stores it in the information recording unit 116. In the present embodiment, the driving frequency in the lens driving unit 114 is a noise frequency.
Information on the noise frequency is delivered to a timing control circuit in the image sensor unit 107. Thereafter, magnetic noise is removed by changing the readout timing of the pixel signal. Details of this point will be described later.

The display unit 119 is a display for displaying the image data sent from the signal processing unit 111. The recording / playback unit 120 records image data and performs processing for playing back the recorded image data. The operation unit 117 includes various operation units such as a shutter button. The operation unit 117 also includes mode switching buttons such as a still image mode and a moving image mode. The motion detection sensor 118 is a sensor that detects a motion of the imaging apparatus such as a camera shake.
As a solid-state image sensor provided in the image sensor unit 107, for example, there is a CCD (Charge Coupled Devices) type image sensor. Moreover, as a solid-state image sensor with which the image sensor section 107 is provided, there is an image sensor such as a CMOS (Complementary Metal Oxide Semiconductor) type image sensor. In the present embodiment, a case where a CMOS image sensor is used as a solid-state image sensor included in the image sensor unit 107 will be described as an example.

In recent years, a CMOS image sensor has attracted attention as a solid-state imaging device that replaces a CCD image sensor.
In general, a CCD image sensor requires a dedicated process for manufacturing a CCD pixel, requires a plurality of power supply voltages for its operation, and requires a plurality of peripheral ICs to be operated in combination. This complicates the system. One reason why CMOS image sensors are attracting attention is that CMOS image sensors overcome these problems.
In addition, the CMOS image sensor can use the same manufacturing process as a general CMOS integrated circuit as its manufacturing process, and can be driven by a single power source. In addition, since analog circuits and logic circuits using a CMOS process can be mixed in the same chip as the CMOS image sensor, the number of peripheral ICs can be reduced.

The output circuit of the CCD image sensor is mainly output in one channel (ch) using an FD amplifier having a floating diffusion (floating diffusion layer). On the other hand, the CMOS image sensor has an FD amplifier for each pixel, and its output is a column that selects one row in the pixel array and simultaneously reads out the signals of the pixels in the selected row in the column direction. Parallel output type is the mainstream. Since the FD amplifier arranged in the pixel may not be able to obtain sufficient driving capability, the data rate is lowered. Therefore, a column parallel output type output is advantageous. Various signal output circuits for column parallel output type CMOS image sensors have been proposed. On the other hand, in order to read out the charge of the CCD image sensor, it is necessary to transfer the charge to the amplifier by a bucket relay, so that it takes some time to read out the signal from the pixel.
As described above, the CMOS image sensor has a plurality of significant advantages.

As a technique used for reading an image signal of a CMOS image sensor, there is the following technique. That is, there is a method in which a signal charge, which is an optical signal generated by a photoelectric conversion element such as a photodiode, is temporarily sampled in a capacitor (capacitor) via a MOS switch arranged in the vicinity thereof, and the sampled capacitance is read out.
In the sampling circuit, noise having an inverse correlation with the value of the sampled capacitance is usually included. In the pixel circuit, when the signal charge is transferred to the capacitor (capacitor) for sampling, the signal charge is completely transferred using the potential gradient, so that no noise is generated in this sampling process. However, noise occurs when the voltage level of the capacitor before the sampling process is reset to a certain reference value.

FIG. 2 is a diagram illustrating an example of a pixel circuit of a CMOS image sensor including four transistors.
The pixel circuit includes, for example, a photodiode 201 as a photoelectric conversion element. The pixel circuit has four transistors, which are a transfer transistor 202, an amplification transistor 203, a selection transistor 204, and a reset transistor 205, as active elements, for one photodiode 201. In the pixel circuit, pixels having photodiodes 201 and active elements (transfer transistors 202, amplification transistors 203, selection transistors 204, reset transistors 205) corresponding to the photodiodes 201 are arranged in a matrix (matrix). .

The photodiode 201 photoelectrically converts incident light into electric charges.
The transfer transistor 202 is connected between the photodiode 201 and the floating diffusion FD. The transfer transistor 202 transfers a charge photoelectrically converted by the photodiode 201 to the floating diffusion FD when a drive signal is given to its gate (transfer gate) through the transfer control line LTx.
The reset transistor 205 is connected between the power supply line LVDD and the floating diffusion FD. The reset transistor 205 resets the potential of the floating diffusion FD to the potential of the power supply line LVDD when a reset signal is given to its gate through the reset control line LRST. More specifically, when resetting the pixel, the transfer transistor 202 is turned on, the charge accumulated in the photodiode 201 is swept out, and then the transfer transistor 202 is turned off, so that the photodiode 201 converts the optical signal into a charge. And accumulate.

The gate of the amplification transistor 203 is connected to the floating diffusion FD. The amplification transistor 203 is connected to the signal line LSGN via the selection transistor 204, and constitutes a constant current source 206 and a source follower outside the pixel.
When an address signal is applied to the gate of the selection transistor 204 through the selection control line LSEL, the selection transistor 204 is turned on. When the selection transistor 204 is turned on, the amplification transistor 203 amplifies the potential of the floating diffusion FD and outputs a voltage corresponding to the potential to the output (vertical) signal line LSGN. The signal voltage output from each pixel through the vertical signal line LSGN is output to the pixel signal readout circuit.

When the actual pixel signal is read, the reset transistor 205 is turned on to reset the floating diffusion FD. Thereafter, the reset transistor 205 is turned off, and the voltage of the floating diffusion FD at that time is output as a reset signal through the amplification transistor 203 and the selection transistor 204. The output at this time is referred to as a P-phase output.
Next, the transfer transistor 202 is turned on to transfer the charge accumulated in the photodiode 201 to the floating diffusion FD. Then, the voltage of the floating diffusion FD at that time is output as an accumulation signal through the amplification transistor 203 and the selection transistor 204. The output at this time is referred to as a D-phase output.
These operations are performed simultaneously in parallel for each pixel of one row because, for example, the gates of the transfer transistor 202, the reset transistor 205, and the selection transistor 204 are connected in units of rows.
One of the most advanced forms of the pixel signal readout circuit of such a column parallel output type CMOS image sensor is a type in which an analog-digital conversion device is provided for each column and a pixel signal is taken out as a digital signal. In the following description, this analog-digital converter is referred to as a column parallel ADC (Analog Digital Converter) as necessary.

FIG. 3 is a diagram illustrating an example of a configuration of a solid-state imaging device 300 (CMOS image sensor) on which a column parallel ADC is mounted.
As shown in FIG. 3, the solid-state imaging device 300 includes a pixel unit 301, a vertical scanning circuit 302, a horizontal transfer scanning circuit 303, a timing control circuit 304, and an ADC group 305. The solid-state imaging device 300 includes a digital-analog converter (DAC (Digital-Analog Converter)) 306, an amplifier circuit (S / A) 307, and a signal processing circuit 308. In the following description, the digital-analog conversion device 306 is referred to as a DAC 306 as necessary.

The pixel unit 301 is configured by arranging pixels as described in FIG. 2 in a matrix, for example. The pixel unit 301 is provided with the following circuit as a control circuit for sequentially reading out signals from the pixel unit 301. That is, the pixel unit 301 includes a timing control circuit 304 that generates an internal clock, a vertical scanning circuit 302 that controls row addresses and row scanning, and a horizontal transfer scanning circuit 303 that controls column addresses and column scanning. Is done.
As described above, when the pixel signal is read, the reset transistor 205 is turned on to reset the floating diffusion FD. Then, the reset transistor 205 is turned off, and the voltage of the floating diffusion FD at that time is output as a P-phase output through the amplification transistor 203 and the selection transistor 204. Next, the transfer transistor 202 is turned on to transfer the charge accumulated in the photodiode 201 to the floating diffusion FD. Then, the voltage of the floating diffusion FD at that time is output as a D-phase output through the amplification transistor 203 and the selection transistor 204.

In the ADC group 305, by using the difference between the D-phase output and the P-phase output as an image signal, not only the variation of the DC component of the output for each pixel but also the reset noise of the floating diffusion FD can be removed from the pixel signal. it can.
In the ADC group 305, ADCs having a comparator 305a, a counter 305b, and a latch 305c are arranged for each column of a pixel matrix in the pixel portion 301. The comparator 305a generates a reference voltage Vslop, which is a ramp waveform obtained by changing the reference voltage generated by the DAC 306 in a stepped manner, and an analog pixel signal Vsl obtained from the pixel via the output signal line LSGN for each row line. Compare. The counter 305b counts the comparison time in the comparator 305a. The latch 305c holds the count result by the counter 305b.

The ADC group 305 has an n-bit digital signal conversion function. An ADC including a comparator 305a, a counter 305b, and a latch 305c is arranged for each vertical signal line LSGN, thereby forming a column parallel ADC block. The output of each latch 305c is connected to the horizontal transfer line 309. The same number of amplifier circuits 307 and signal processing circuits 308 as the bit width of the horizontal transfer line 309 are arranged.
FIG. 4 is a diagram illustrating (a part of) one column of pixels included in the pixel unit 301 of FIG. 3 and one of the ADCs included in the ADC group 305. 5A is a diagram illustrating an example of an output waveform of the main signal in FIG. 4 when noise cannot be removed, and FIG. 5B illustrates an example of an output waveform of the main signal in FIG. 4 when noise can be removed. FIG.

  As shown in FIGS. 5A and 5B, the time difference between the P-phase output timing and the D-phase output timing is ΔT, and in the following description, it is simply referred to as the time difference ΔT as necessary. In the ADC group 305, the pixel output (potential Vsl) that is an analog image signal read to the vertical signal line LSGN is compared with the reference voltage Vslop by the comparator 305a arranged for each column. 5A and 5B, the reference voltage Vslop has a slope waveform (ramp waveform) that changes linearly with a certain slope. At this time, like the comparator 305a, the counter 305b arranged for each column operates. The reference voltage Vslop having a ramp waveform and the count value of the counter 305b change while taking a one-to-one correspondence, whereby the potential (analog pixel signal) Vsl of the vertical signal line LSGN is converted into a digital pixel signal. The change in the reference voltage Vslop converts the change in voltage into a change in time, and the analog value is converted into a digital value by counting the time in a certain period (clock). When the potential Vsl of the vertical signal line LSGN, which is an analog signal, and the reference voltage Vslop intersect, the output of the comparator 305a is inverted. Thereby, the input clock of the counter 305b is stopped and AD conversion is completed.

In the P-phase period of FIG. 5A, when the potential Vsl of the vertical signal line LSGN, which is an analog signal, becomes equal to the reference voltage Vslop, the output of the comparator 305a is inverted from the “H” level to the “L” level. In response to the polarity inversion of the comparator 305a, the counter 305b stops the counting operation, and the latch 305c holds the count value corresponding to the P-phase output (ΔV).
Next, in the D phase period, when the potential Vsl of the vertical signal line LSGN, which is an analog signal, becomes equal to the reference voltage Vslop, the output of the comparator 305a is inverted from the “H” level to the “L” level. In response to the polarity inversion of the comparator 305a, the counter 305b stops the count operation, and the latch 305c holds the count value corresponding to the output voltage Vout shown in FIG. 5A. As shown in FIG. 5A, the output voltage Vout is a value obtained by subtracting the P-phase output (= ΔV) from the D-phase output when the polarity of the comparator 305a is inverted in the D-phase period. Thereby, the output voltage Vout which is the difference between the D-phase output and the P-phase output can be obtained.

After the above AD conversion period is completed, the data (output voltage) held in the latch 305c by the horizontal transfer scanning circuit 303 is input to the signal processing circuit 308 via the horizontal transfer line 309 and the amplifier circuit 307, and two-dimensionally. An image is generated. In this way, column parallel output processing is performed.
However, there is a case where magnetism generated from the actuator 105b of the correction lens driving unit 105 or the lens driving unit 114 for driving the lens 101 and the focus lens 104 is applied to the vertical signal line LSGN as noise. Specifically, when an arbitrary driving device is PWM-driven, the magnetic flux generated from the coil of the driving device penetrates the signal line of the CMOS image sensor. Thereby, magnetism by electromagnetic induction is generated in the signal line, and noise is generated in the signal line.

  Since the solid-state imaging device 300 equipped with the column parallel ADC simultaneously performs AD conversion for one horizontal line, when this noise is added, the influence of noise is generated on all signals for one horizontal line. At this time, since the image appears as horizontal streak noise, the influence of the noise is conspicuous visually and the image quality is degraded. In this embodiment, by changing the AD conversion timing so that noise is generated at the same level in the P-phase output and the D-phase output, the influence of the noise is removed from the pixel signal, and the generation of the horizontal streak noise is suppressed. To do.

5A and 5B show a noise waveform N due to driving of the actuator as an example. In the case shown in FIG. 5A, since the level (phase) of the noise waveform N differs between the P-phase output timing and the D-phase output timing, the difference between the P-phase output timing and the D-phase output timing is the noise level. The impact is greatly included.
Therefore, in the present embodiment, as shown in FIG. 5B, the level (phase) of the noise waveform N is matched between the P-phase output timing and the D-phase output timing by shifting the D-phase output timing. That is, the time difference ΔT between the timing of the P-phase output and the timing of the D-phase output is matched with an integer multiple of the reciprocal of the noise frequency. Then, the influence of noise on the P-phase output timing and the D-phase output timing is the same phase. Therefore, if the difference between the P-phase output timing and the D-phase output timing is taken, the influence of the noise is canceled. Can do. Even when the time difference ΔT between the timing of the P-phase output and the timing of the D-phase output cannot be completely matched with an integer multiple of the reciprocal of the noise frequency, the time difference ΔT is made close to an integer multiple of the reciprocal of the noise frequency. Noise can be reduced.
That is, noise can be removed when the following expression (1) is satisfied.
ΔT = n / f (1)
Here, n is an integer, and f is a noise frequency of the lens driving unit 114 and the like.

FIG. 6 is a flowchart for explaining an example of a method for removing magnetic noise when there is one lens driving unit 114 and one noise frequency.
First, in step S <b> 601, the control unit 115 reads “a value of a known noise frequency f generated by the lens driving unit 114” stored in the information recording unit 116.
Next, in step S602, the control unit 115 calculates the equation (1) to calculate a time difference ΔT between the P-phase output timing and the D-phase output timing.
Next, in step S603, the control unit 115 ensures that the interval between the P-phase output timing and the D-phase output timing output by the timing control circuit 304 becomes (or approaches) the time difference ΔT calculated in step S602. A synchronization pulse is set (see FIG. 5B). The timing control circuit 304 sends the synchronization pulse set in this way to the DAC 306, the vertical scanning circuit 302, and the horizontal transfer scanning circuit 303.

  As described above, in this embodiment, the reference voltage in the D-phase period is such that the period of noise is a time difference ΔT between the P-phase output timing and the D-phase output timing, which is an integral multiple of the reciprocal of the noise frequency f. The timing for starting the output of Vslop was adjusted. Therefore, the output voltage Vout can be output while the time difference ΔT between the P-phase output timing and the D-phase output timing is maintained as an integer multiple of the reciprocal of the noise frequency f. Therefore, it is possible to reduce noise recorded in a captured image without performing settings that assume various situations in advance. Further, as shown in the following embodiments, it is possible to reduce noise generated in various situations in a captured image. Therefore, it is possible to easily and reliably reduce the noise recorded in the photographed image.

In the present embodiment, the control unit 115 performs the calculation of the time difference ΔT. However, the result of the calculation of the time difference ΔT is stored in the information recording unit 116 in advance, and may be read and executed. Good. For example, the calculation of the time difference ΔT may be executed by the timing control circuit 304. In any method, the output voltage Vout can be output while the time difference ΔT between the P-phase output timing and the D-phase output timing is maintained as an integer multiple of the reciprocal of the noise frequency f.
In the present embodiment, the case where the lens driving unit 114 is driven by a PWM driving method has been described as an example. However, the driving method of the lens driving unit 114 is not limited to this, and other driving methods may be used. For example, even if the driving method of the lens driving unit 114 is a phase difference detection method, PZD (Piezo Drive), or the like, noise can be removed in the same manner as described in the present embodiment.

  The imaging device is not limited to a digital camera or a digital video camera. For example, the imaging apparatus described in the present embodiment is configured as a small camera module, and is used in various portable devices such as a mobile phone, a PDA, a portable game machine, a portable video or audio player / recorder, a voice recorder, and an electronic notebook. Can be installed. In addition, such a small camera module includes an information processing device such as a PC and a PDA, an audio device, a recording / playback device, an information home appliance, a door phone device, an authentication device, a robot, a toy, a remote controller, etc. Can be mounted on electronic equipment. In addition, the imaging apparatus according to the present embodiment can be applied to a camera that mainly functions as an imaging function, such as a digital camera (a still camera, a single-lens reflex camera, or the like), a digital video camera, or a surveillance camera.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. In the first embodiment described above, the case where there is one lens driving unit 114 has been described as an example. On the other hand, in this embodiment, a case where a plurality of different lens driving units are driven at different noise frequencies will be described. Thus, the present embodiment and the first embodiment are mainly different in configuration and operation by driving a plurality of different lens driving units at different noise frequencies. Therefore, in the description of the present embodiment, the same portions as those in the first embodiment are denoted by the same reference numerals as those in FIGS.

  FIG. 7 is a diagram illustrating an example of the configuration of the imaging apparatus according to the present embodiment. The imaging apparatus of this embodiment includes two lens driving units 114a and 114b instead of the lens driving unit 114 of the imaging apparatus of the first embodiment shown in FIG. FIG. 8 is a flowchart for explaining an example of a method for removing magnetic noise when two lens driving units 114a and 114b are driven at different noise frequencies. In the description of the present embodiment, the time difference ΔT between the P-phase output timing and the D-phase output timing is expressed as ΔT ′. Further, it is assumed that the lens driving units 114a and 114b operate at known noise frequencies f1 and f2, respectively.

First, in step S801, the control unit 115 reads “values of known noise frequencies f1 and f2 generated by the lens driving unit 114a and the lens driving unit 114b” stored in the information recording unit 116.
Next, in step S802, the control unit 115 sets the time difference ΔT ′ between the P-phase output timing and the D-phase output timing to the reciprocals 1 / f1 and 1 / f2 of the noise frequencies f1 and f2 acquired in step S801. Calculated as the least common multiple.

Next, in step S803, the control unit 115 ensures that the relationship between the timing of the P-phase output and the timing of the D-phase output output from the timing control circuit 304 becomes (or approaches) the time difference ΔT ′ calculated in step S802. A synchronization pulse is set (see FIG. 5B). The timing control circuit 304 sends the synchronization pulse set in this way to the DAC 306, the vertical scanning circuit 302, and the horizontal transfer scanning circuit 303.
Here, the case where there are two lens driving units 114a and 114b, which are driven at different noise frequencies, has been described as an example. However, these numbers are not limited to two. That is, even when there are n different lens driving units (n is an arbitrary natural number) and driving is performed at different noise frequencies f1, f2,..., Fn, synchronization is performed in the same manner as in the flowchart of FIG. Pulse can be set. In this case, first, in step S801, known noise frequencies f1, f2,..., Fn generated by the respective lens driving units 114 are acquired. In step S802, the time difference ΔT ′ between the P-phase output timing and the D-phase output timing is set to the reciprocals 1 / f1, 1 / f2,..., 1 of the noise frequencies f1, f2,. Calculated as the least common multiple of / fn.

  As described above, according to the present embodiment, even when there are a plurality of lens driving units that are driven at different noise frequencies, the recorded image is recorded as described in the first embodiment. Noise can be easily and reliably reduced.

In the present embodiment, the description has been made on the assumption that the control unit 115 performs the calculation of the time difference ΔT ′. However, the result of the calculation of the time difference ΔT ′ is stored in the information recording unit 116 in advance, and is read and executed. May be. For example, the calculation of the time difference ΔT ′ may be executed by the timing control circuit 304. In any method, the time difference ΔT ′ between the P-phase output timing and the D-phase output timing remains an integral multiple of the least common multiple of the reciprocals of the noise frequencies f1, f2,. The output voltage Vout can be output.
In the present embodiment, the time difference ΔT ′ is the least common multiple of the inverses 1 / f1, 1 / f2,..., 1 / fn of the noise frequencies f1, f2,. However, the time difference ΔT ′ may be an integer multiple of the least common multiple of the reciprocals 1 / f1, 1 / f2,..., 1 / fn of the noise frequencies f1, f2,.
Also in the present embodiment, various modifications described in the first embodiment can be employed.

(Third embodiment)
Next, a third embodiment of the present invention will be described. In the second embodiment, the case where a plurality of different lens driving units are driven at different noise frequencies has been described as an example. In contrast, in the present embodiment, a case where one lens driving unit is driven at a plurality of noise frequencies that vary with time will be described. As described above, the present embodiment and the first and second embodiments are mainly different in configuration and operation by driving one lens driving unit with a plurality of noise frequencies that vary with time. Therefore, in the description of the present embodiment, the same parts as those in the first and second embodiments are denoted by the same reference numerals as those in FIGS.

An example of the configuration of the imaging apparatus of the present embodiment is the same as that shown in FIG. Here, for example, the case where the noise frequency of the lens driving unit 114 changes by switching the operation mode will be described as an example.
FIG. 9 is a diagram illustrating an example of the time transition of the noise frequency and the time transition of the time difference ΔT between the P-phase output timing and the D-phase output timing. In FIG. 9A, the horizontal axis represents time, and the vertical axis represents noise frequency. In FIG. 9B, the horizontal axis represents time and the vertical axis represents time difference ΔT.

In the example shown in FIG. 9, the lens driving unit 114 is driven in the mode A that operates at the noise frequency f from the start of operation to time t1, and from time t1 to t2, the noise frequency f is 2 from time 0 to t1. It is assumed that the driving is performed in the mode B operating at the double noise frequency 2 × f. The time difference ΔT1 in mode A is expressed by the following equation (2), and the time difference ΔT2 in mode B is expressed by the following equation (3). It becomes.
ΔT1 = n / f (2)
ΔT2 = m / (2 × f) (3)
Here, n and m are each an arbitrary integer.

FIG. 10 is a flowchart for explaining an example of a method for removing magnetic noise when one lens driving unit 114 is driven at a plurality of noise frequencies f1 and f2 that vary with time. In FIG. 10, it is assumed that the operation is in the A mode at the start of the operation due to the setting of the input mode changeover switch of the operation unit 117 or the like.
First, in step S1001, the control unit 115 determines whether the current mode of the imaging apparatus (lens driving unit 114) is the A mode or the B mode. As a result of this determination, if the current mode is mode A, that is, if the time t1 has not elapsed since the power was turned on, it is determined that the current mode is the A mode, and the process proceeds to step S1002.

In step S <b> 1002, the control unit 115 reads “a value of the known noise frequency f generated by the lens driving unit 114” stored in the information recording unit 116.
Next, in step S1103, the control unit 115 calculates (2) to calculate the time difference ΔT1 between the P-phase output timing and the D-phase output timing.

  Next, in step S1004, the control unit 115 causes the interval between the P-phase output timing and the D-phase output timing output by the timing control circuit 304 to be (or approach) the time difference ΔT1 calculated in step S1003. Set the sync pulse. The timing control circuit 304 sends the synchronization pulse set in this way to the DAC 306, the vertical scanning circuit 302, and the horizontal transfer scanning circuit 303.

Thereafter, the process returns to step S1001, and the control unit 115 determines the mode again, and repeats the processes of steps S1001 to S1004 until the mode is switched. If it is determined in step S1001 that the current mode has been switched to mode B after the time t1 has elapsed since the power was turned on, the process proceeds to step S1005.
In step S1005, the control unit 115 reads the “value of the known noise frequency 2 × f generated by the lens driving unit 114” stored in the information recording unit 116.
Next, in step S1006, the control unit 115 calculates Formula (3) to calculate a time difference ΔT2 between the P-phase output timing and the D-phase output timing.

Next, in step S1007, the control unit 115 causes the interval between the P-phase output timing and the D-phase output timing output from the timing control circuit 304 to be (or approach) the time difference ΔT2 calculated in step S1006. Set the sync pulse. The timing control circuit 304 sends the synchronization pulse set in this way to the DAC 306, the vertical scanning circuit 302, and the horizontal transfer scanning circuit 303.
Thereafter, the process returns to step S1001, and the control unit 115 determines the mode again, and repeats the processes of steps S1001, S1005 to S1107 until the mode is switched.

  As described above, according to the present embodiment, even when one lens driving unit is driven at a plurality of noise frequencies that vary depending on time, the captured image is the same as described in the first and second embodiments. Can be easily and reliably reduced.

  In the present embodiment, description has been made on the assumption that the control unit 115 performs the calculation of the time differences ΔT1 and ΔT2, but the result of the calculation of the time differences ΔT1 and ΔT2 is stored in the information recording unit 116 in advance and is read out. May be executed. For example, the timing control circuit 304 may execute the calculation of the time differences ΔT1 and ΔT2. In any method, the output voltage Vout is output while the time differences ΔT1 and ΔT2 between the timing of the P-phase output and the timing of the D-phase output remain an integer multiple of the reciprocal of the noise frequency f, 2 × f. Things are possible.

In the present embodiment, the case of switching between two modes has been described. However, even when the number of mode switching is k (k: any integer), the same method as described in the present embodiment is used. be able to. For example, in step S1001 in FIG. 10, it is determined which of the k modes is the current mode, an integer multiple of the reciprocal of the noise frequency for the determined mode is calculated, and the value is calculated as the P-phase output. The time difference between the timing and the D-phase output timing may be used.
Also in this embodiment, various modifications described in the first and second embodiments can be adopted.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described. In the first to third embodiments, the case where the driving frequency of the lens driving unit 114 is a noise frequency has been described as an example. However, in addition to the actuator for driving the lens, similar noise may be generated by the switching operation of the voltage control transistor of the power supply circuit. Specifically, when the power supply circuit performs a switching operation, the magnetic flux generated from the coil of the power supply circuit penetrates the signal line of the CMOS image sensor. Thereby, magnetism by electromagnetic induction is generated in the signal line, and noise is generated in the signal line.

The switching operation frequency of the power supply circuit varies from individual to individual, and fluctuates due to factors such as temperature. For this reason, the timing of the P-phase output and the timing of the D-phase output that can cancel the influence of noise cannot be uniquely determined.
Therefore, in the present embodiment, an image is picked up by the image pickup apparatus itself, and the frequency of the data of the image is analyzed to specify the switching operation frequency of the power supply circuit as the noise frequency f. If the noise frequency f can be identified, as described in the first embodiment, the time difference ΔT is calculated by the equation (1), and the interval between the P-phase output timing and the D-phase output timing is calculated as the calculated time difference ΔT. The synchronization pulse can be set to be (or approach). Thereby, the noise recorded on an image can be reduced.
As described above, the present embodiment and the first to third embodiments are mainly different in configuration and operation due to different sources of noise. Therefore, in the description of the present embodiment, the same parts as those in the first to third embodiments are denoted by the same reference numerals as those in FIGS.

FIG. 11 is a flowchart for explaining an example of a method for deriving the switching operation frequency of the power supply circuit as the noise frequency f. Here, the nominal value of the switching operation frequency of the power supply circuit is 2.5 MHz (2500 kHz), and there is an individual variation of 10%.
First, the control unit 115 instructs photographing in the first drive mode for noise frequency detection. When shooting is performed based on this instruction, an image signal is output from the solid-state imaging device 300 and temporarily stored in the signal processing unit 111 (memory). Noise is mixed in the image signal due to the influence of the switching operation of the power supply circuit. Therefore, the control unit 115 specifies the noise frequency f by performing frequency analysis on the image signal. Here, in order to suppress other influences, it is desirable to capture a black image by blocking light input to the solid-state imaging device 300 (each pixel). In a normal imaging apparatus, light can be blocked by closing the mechanical shutter 106.

  As the data of the image signal for noise frequency detection, it is sufficient that the data for one column in the vertical direction of the solid-state imaging device 300 is at least. This is because the solid-state imaging device 300 mounted with the column parallel ADC simultaneously performs AD conversion for one line in the horizontal direction, so that when this noise is added, the noise is similarly applied to all signals for one line in the horizontal direction. This is because of the influence of. In addition, after averaging the data for one line in the horizontal direction using the data of the two-dimensional image signal, the discrete data in the vertical direction may be generated.

In the first drive mode, the HD cycle (horizontal synchronization period) is 500 kHz. Therefore, image signal data obtained when the power supply circuit performs a switching operation in the first drive mode is discrete data having a sampling frequency of 500 kHz. Therefore, in step S1102, the control unit 115 performs a discrete Fourier transform (DFT) on the discrete data to derive a frequency at which a peak appears.
FIG. 12 is a diagram illustrating an example of a relationship between a switching operation frequency and a frequency at which a peak appears in the discrete Fourier transform. Here, description will be made assuming that a peak of 150 kHz appears as a result of performing discrete Fourier transform on the image signal data obtained when the switching of the power supply circuit performs the switching operation in the first drive mode.

  The image signal is mixed with noise of the switching operation frequency of the power supply circuit, and as described above, it is known that the switching operation frequency is around 2500 kHz. Since the Nyquist frequency is 250 kHz, it can be considered that the 150 kHz peak is visible. Therefore, the control unit 115 can determine that the switching operation frequency is 2350 kHz or 2650 kHz from the data of the image signal obtained when the switching of the power supply circuit performs the switching operation in the first drive mode.

Next, in step S1103, the control unit 115 instructs shooting in the second drive mode for noise frequency detection. When shooting is performed based on this instruction, image signal data is output from the solid-state imaging device 300 and temporarily stored in the signal processing unit 111 (memory), as described above.
In the second drive mode, the HD cycle (horizontal synchronization period) is 490 kHz. Therefore, image signal data obtained when the power supply circuit performs a switching operation in the second drive mode is discrete data having a sampling frequency of 490 kHz. Therefore, in step S1104, the control unit 115 performs a discrete Fourier transform (DFT) on the discrete data to derive a frequency at which a peak appears. Here, it is assumed that a peak of 100 kHz appears as a result of performing discrete Fourier transform on image data obtained when the switching of the power supply circuit performs a switching operation in the second drive mode. Then, the control unit 115 can determine that the switching operation frequency is 2350 kHz from the image data obtained when the switching of the power supply circuit performs the switching operation in the second drive mode.

  Next, in step S1105, the control unit 115 derives a switching operation frequency from the results of steps S1102 and S1104. In the example described above, the control unit 115 can determine that the switching operation frequency is 2350 kHz by combining the results when the first and second driving modes are taken. In the present embodiment, the frequency derivation process is realized in this way. Then, for example, the processing of steps S602 and S603 in FIG. 6 is performed using the switching operation frequency thus derived as the noise frequency f.

  Here, imaging for detecting a noise frequency (switching operation frequency) is performed for each imaging device at least once in the manufacturing process of the imaging device. However, it is not always necessary to do this. For example, it may be executed every time the imaging apparatus is activated. Further, the user may be able to set the shooting timing at an arbitrary timing. In addition, in the case of an imaging apparatus including a temperature sensor attached to a power supply circuit or the vicinity thereof, for example, according to the temperature sensor temperature detection result (for example, the temperature of the temperature sensor fluctuates beyond a predetermined range). Shooting) may be performed.

  As described above, in the present embodiment, the imaging device itself captures an image (black image) with a different horizontal synchronization period, specifies the switching operation frequency of the power supply circuit by analyzing the frequency of the image data, The switching operation frequency is a noise frequency f. Therefore, it is possible to suppress the noise generated by the switching operation of the power supply circuit from being recorded in the image even when the switching operation frequency is changed due to individual differences of the power supply circuits (switching elements).

(Fifth embodiment)
Next, a fifth embodiment of the present invention will be described. In the present embodiment, a case will be described in which noise recorded in an image is suppressed when the gain setting in the AD conversion circuit of the solid-state imaging device 300 is changed. Thus, the present embodiment and the first to fourth embodiments are mainly different in configuration and operation due to different sources of noise. Therefore, in the description of the present embodiment, the same parts as those in the first to fourth embodiments are denoted by the same reference numerals as those in FIGS.

In the AD conversion method referred to as a single slope integration type, the result of applying gain adjustment to an analog signal to be processed by AD conversion by changing the slope of the reference signal (reference voltage Vslop) supplied to the comparator 305a. A signal can be obtained.
The reference voltage Vslop only needs to have a waveform that changes linearly with a certain slope as a whole. The reference voltage Vslop may have a smooth slope shape or change sequentially on the stairs. It may be.

FIG. 13 is a diagram illustrating an example of the configuration of the solid-state imaging device 300 according to the present embodiment and the configuration of the control unit 115 for adjusting the gain of the AD conversion circuit of the solid-state imaging device 300. In FIG. 13, a part of the configuration is omitted for the convenience of description.
The timing control circuit 304 has a function of a timing generator TG that supplies a clock signal necessary for the operation of each unit and a pulse signal having a predetermined timing. In addition, the timing control circuit 304 has a function of a communication interface for inputting the master clock CLK, data data for instructing an operation mode, and the like, and outputting data data including information on the solid-state imaging device 300.

  The timing control circuit 304 generates an internal clock based on the input clock (master clock) CLK and the high-speed clock generated by the clock conversion circuit 1301. By using a signal derived from the high-speed clock generated by the clock conversion circuit 1301, AD conversion processing or the like can be operated at high speed. Also, motion extraction and compression processing requiring high-speed calculation can be performed using a high-speed clock. Also, parallel data output from a column processing unit (not shown) can be converted into serial data and image data can be output outside the device. By doing so, it is possible to adopt a configuration in which high-speed operation output is performed with a smaller number of terminals than the number of bits of AD-converted digital data.

  The clock conversion circuit 1301 includes a multiplication circuit that generates a pulse signal having a clock frequency faster than the frequency of the master clock CLK input to the timing control circuit 304. For example, the clock conversion circuit 1301 receives a low-speed clock from the timing control circuit 304, and generates a clock having a frequency twice or more higher based on the low-speed clock. Various known circuits can be used as the multiplication circuit of the clock conversion circuit 1301.

The timing setting unit 1302 determines the start timing of the output of the reference signal (reference voltage Vslop) for performing periodic noise reduction. Details of this will be described later.
The noise information storage unit 1303 stores noise information of a noise source that affects the solid-state imaging device 300. In the present embodiment, the noise information includes each noise frequency (or period) generated inside the imaging apparatus, a known noise frequency (or period) generated outside the imaging apparatus, and noise calculated based on each noise information. Timing information for reduction and the like.

The noise detection unit 1304 detects periodic noise that appears in the captured image. Noise information relating to noise detected by the noise detection unit 1304 is held in the noise information storage unit 1303.
The gain setting unit 1305 determines the gain of the AD conversion circuit of the solid-state imaging device 300 based on the captured image. Further, when the manual mode is set in the imaging apparatus, the gain setting unit 1305 sets a gain value instructed by the operation of the operation unit 117 by the user.
The target luminance setting unit 1306 determines the luminance value of the image that reduces noise.

FIG. 14 is a diagram illustrating an example of an output waveform of the DAC 306.
The DAC 306 is supplied with a count clock DAC_CLK for driving DA conversion from the timing control circuit 304. The DAC 306 generates, for example, a linear ramp waveform that decreases linearly in synchronization with the count clock DAC_CLK, and supplies the reference voltage Vslop for AD conversion to the comparator 305a of the column AD circuit.
Here, the DAC 306 sets the initial voltage based on “information indicating the initial value of the reference voltage Vslop” from the gain setting unit 1305. Further, the DAC 306 sets a step width ΔRAMP, which is a voltage change per clock, based on information indicating the slope (change amount per unit time) of the reference voltage Vslop, and is 1 for each unit time (count clock). Change the count value step by step. Actually, the maximum voltage width with respect to the maximum count number (for example, 1024 in 10 bits) of the count clock DAC_CLK is set. Note that any circuit configuration for setting the initial voltage may be used.

As shown in FIG. 14, the step width ΔRAMP of the reference voltage Vslop per count clock CNT_CLK is 1-bit resolution.
When the frequency of the count clock DAC_CLK is constant, the 1-bit resolution becomes rough when the slope of the reference voltage Vslop is steep, but when the slope of the reference voltage Vslop is gentle, the step width ΔRAMP is small and the 1-bit resolution is precise. Become. That is, when the slope of the reference voltage Vslop is steep, the number of count clocks with respect to the step width ΔRAMP decreases, and the gain of the AD conversion circuit decreases. On the other hand, when the slope of the reference voltage Vslop is gentle, the number of count clocks with respect to the step width ΔRAMP increases, and the gain of the AD conversion circuit increases.

On the other hand, when the slope of the reference voltage Vslop is constant, the step width ΔRAMP is small and the 1-bit resolution is precise when the frequency of the count clock DAC_CLK is high. That is, when the frequency of the count clock DAC_CLK is low, the number of count clocks with respect to the step width ΔRAMP is reduced, and the gain of the AD conversion circuit is reduced. On the other hand, when the frequency of the count clock DAC_CLK is high, the number of count clocks for the step width ΔRAMP increases, and the gain of the AD conversion circuit increases.
In any of the above methods, the gain can be adjusted during AD conversion by adjusting the number of count clocks with respect to the change amount of the reference voltage Vslop per unit time. Although not shown, both methods may be combined. Thus, the gain of the AD converter circuit can be increased by increasing the frequency of the count clock DAC_CLK. Further, the gain of the AD converter circuit may be increased by changing the change rate of the reference voltage Vslop per unit count clock DAC_CLK to change the slope of the reference voltage Vslop. In this embodiment, any method can be adopted.

FIG. 15A is a diagram illustrating an example of the output start timing of the reference voltage Vslop when the noise cannot be removed, and FIG. 15B is a diagram illustrating an example of the output start timing of the reference voltage Vslop when the noise can be removed.
In FIG. 15, times t0 and t3 are timings for starting output of the reference voltage Vslop in each of the P phase and the D phase. Times t1 and t2 are timings for determining the P-phase output (the potential Vsl of the vertical signal line LSGN in the P-phase) at each of the gains G1 and G2. Times t4 and t5 are timings for determining the D-phase output (the potential Vsl of the vertical signal line LSGN in the D-phase) in each of the gains G1 and G2.
The reference voltage 1501 indicates the reference voltage Vslop (waveform) at the gain G1, and the reference voltage 1502 indicates the reference voltage Vslop (waveform) at the gain G2.
The signal value VP is a P-phase output (the potential Vsl of the vertical signal line LSGN in the P phase), and the signal value VD is a D-phase output (the potential Vsl of the vertical signal line LSGN in the P phase). The initial voltage setting value V0 is an initial value (initial voltage) of the reference voltage Vslop.

When the reference voltages 1501 and 1502 match the signal values VP and VD, the output of the comparator 305a is inverted and the signal value is determined.
As shown in FIG. 15A, when the output start timings of the reference voltages 1501 and 1502 are the same, the comparator 305a outputs signal values VD and VP (D-phase output and P-phase output) when the gain is G1 and when the gain is G2. The timing interval for determining the difference is different. Further, the level (phase) of the noise waveform N differs between the P-phase output timing and the D-phase output timing depending on the signal value and the gain setting (see the differences Y1 and Y2 in FIG. 15A). For this reason, the difference between the P-phase output and the D-phase output is greatly affected by noise.

  Therefore, as shown in FIG. 15B, by shifting the output start timing of the reference voltages 1501 and 1502 in the D phase, the level (phase) of the noise waveform N with respect to an arbitrary signal value is changed from the P phase output timing and the D phase output timing. Match the output timing. In this case, since the influence of noise on the P-phase output and the D-phase output is the same phase, the influence of the noise can be canceled by taking the difference between the P-phase output and the D-phase output.

In FIG. 15B, time tDG1 (0) is the timing of starting to output the reference voltage Vslop in the D phase. Time tDG1 (VD) is a timing for determining the D-phase output. In order to reduce the noise in accordance with the gain value of the AD conversion circuit, the following relationship (4) should be satisfied with respect to the period TN of the noise waveform N.
tDG1 (VD) −tPG1 (VP) = TN × n (4)
However, n is an integer. In FIG. 15B, n is “3”.

In the case of the gain G1, the timing tPG1 (VP) for determining the P-phase output and the timing tDG1 (VP) for determining the D-phase output have the following relations (5) and (6), respectively.
tPG1 (VP) = t0 + (VP−V0) / ΔRAMP (G1) + (VN−VP) / ΔRAMP (G1) (5)
tDG1 (VD) = tDG1 (0) + (VP−V0) / ΔRAMP (G1) + (VD−VP) / ΔRAMP (G1) + (VN−VD) / ΔRAMP (G1) (6)
However, ΔRAMP (G1) is the step width ΔRAMP of the reference voltage Vslop when the gain is G1. Further, VN is a fluctuation voltage due to the influence of the target periodic noise, for example, a signal fluctuation voltage due to the influence of magnetic noise.

When coincident with the period TN of the noise waveform N, the following expression (7) is established.
VN−VD = VN−VP (7)
Therefore, the output start timing of the reference voltage Vslop in the D phase is expressed by the following equation (8).
tDG1 (0) = TN × n− (VD−VP) / ΔRAMP (G1) (8)
Formula (8) represents the following. That is, after the elapse of time of (n × noise waveform period− (target luminance value / rate of change of reference signal per unit clock (gain setting))) from the timing of starting the output of the reference voltage Vslop in the P phase (time t0). The output of the reference voltage Vslop in the D phase may be started.

The timing for starting the output of the reference voltage Vslop in the D phase (time tDG1 (0)) can be calculated each time the gain is changed by the timing setting unit 1302. In addition, for example, the output start timing (time tDG1 (0)) of the reference voltage Vslop in the D phase may be stored in advance as a table for each target luminance value in the noise information storage unit 1303. If the target luminance value is known in advance, “output start timing of the reference voltage Vslop in D phase (time tDG1 (0))” corresponding to the target luminance value is stored in the noise information storage unit 1303 in advance. May be.
When the target brightness value is changed according to the captured image, the target brightness value is calculated from the immediately preceding captured image, and the output start timing of the reference voltage Vslop in the D phase (time tDG1 (0 )) May be calculated.

  Here, the case where the reference signal Vslop is common for each row of the image has been described as an example. However, a different reference signal Vslop may be generated for each specific area of the pixel. For example, depending on the configuration of the sensor, a different reference signal Vslop may be generated for each of RGB pixels having different sensitivities. In this case, the delay amount of the output start timing (time tDG1 (0)) of the reference voltage Vslop in the D phase may be changed for each reference signal Vslop.

Next, an example of changing the output start timing of the reference voltage Vslop when the imaging apparatus is operating will be described.
FIG. 16 is a flowchart for explaining an example of a method for changing the output start timing of the reference voltage Vslop when the imaging apparatus is operating.
When the operation of the imaging apparatus starts, first, in step S1601, the gain setting unit 1305 sets a gain. When the shooting mode of the imaging apparatus is set to auto, the gain setting unit 1305 sets an optimum gain based on, for example, luminance information of the shot image. Further, when the shooting mode of the imaging apparatus is set manually, for example, the gain is set in accordance with the ISO sensitivity setting and the like selected by the user by operating the operation unit 117. In the present embodiment, the gain information acquisition process is performed in this way.

  Next, in step S1602, the target luminance setting unit 1306 sets a target luminance value for reducing periodic noise. The target luminance value may be a fixed value for each gain setting, or may be changed for each captured image. When the target luminance value is changed for each captured image, the target luminance value detection area may be the entire captured image or a predetermined part of the captured image. For example, an integral value, average value, maximum value, minimum value, or the like of the luminance of each pixel in such a detection area can be calculated as the target luminance value.

FIG. 17 is a diagram conceptually illustrating an example of a captured image. FIG. 18 is a diagram illustrating a histogram (FIG. 18A) of luminance values of the captured image shown in FIG. 17 and a relationship (FIG. 18B) between the luminance value and the S / N ratio of the pixel signal.
In FIG. 17, a photographed image 1701 includes a subject 1702 of uniform color and brightness, such as a wall, and a main subject 1703 such as a human face.
In this case, the luminance value (integral value, average value, maximum value, minimum value, etc.) of the main subject 1703 selected by the user can be set as the target luminance value.
Further, for example, as shown in FIG. 18A, a histogram of the entire captured image 1701 can be acquired for the captured image 1701, and the peak luminance value can be set as the target luminance value.

In general, as shown in FIG. 18B, since the S / N ratio of the pixel signal decreases as the luminance value decreases, the influence of noise is conspicuous at low luminance. Further, when the gain is large, the noise amount also increases at a magnification corresponding to the increase in gain, so that the influence of noise becomes more prominent. In the histogram, when peaks occur at a plurality of luminance values, the luminance value with the lowest S / N ratio may be selected as the target luminance value.
Further, as described above, the solid-state imaging device 300 equipped with the column parallel ADC simultaneously performs AD conversion for one line in the horizontal direction. Therefore, when noise is added, noise is applied to all signals for one line in the horizontal direction. Impact will occur. At this time, since the image appears as horizontal stripe noise, the influence of the noise is conspicuous visually and the image quality is degraded.

Here, since the AD conversion timing depends on the luminance value, in the case of a subject in which the luminance value is dispersed, the amount of noise to be superimposed is also distributed according to the luminance value. As a result, noise appearing in the image is close to random noise, and is less noticeable as a fixed pattern.
However, since the amount of noise is uniform in the horizontal direction on a uniform surface having the same luminance value, the noise appears as a fixed pattern in the image and is easily recognized by the user. Therefore, a uniform surface of color and luminance in the image may be extracted, and the luminance value (integrated value, average value, maximum value, minimum value, etc.) of this region may be set as a target luminance value for reducing noise. . Note that a pixel area extraction method for obtaining a target luminance value by extracting a uniform luminance surface from a captured image is omitted because it is out of the scope of the present invention, but can be easily realized by a known image processing method.
In the present embodiment, the target luminance value acquisition process is performed as described above.

Returning to the description of FIG. 16, when the timing setting unit 1302 receives a gain change command from the gain setting unit 1305 in step S1603, the timing setting unit 1302 acquires noise frequency information from the noise information storage unit 1303. In addition, the timing setting unit 1302 acquires information on DAC_CLK and CNT_CLK from the timing control circuit 304 through communication / timing control. Then, the timing setting unit 1302 determines the output start timing of the reference voltage Vslop in the D phase based on these pieces of information.
What is stored in the noise information storage unit 1303 may be not the noise frequency but the period of noise. Further, “the timing of starting to output the reference voltage Vslop in the D phase according to the target brightness value and the set value of the gain may be used. Here, the frequency information of the noise source is stored in the noise information storage unit 1303 in advance. Although stored, for example, the noise detection unit 1304 may detect the noise frequency from the captured image, and the timing setting unit 1302 may acquire information on the noise frequency.
In the present embodiment, the noise frequency information acquisition process is performed as described above.

In step S1604, the timing setting unit 1302 changes the output start timing of the reference signal Vslop in the D phase based on the gain and the target luminance value set in steps S1602 and S1603. As described above, this timing can be obtained by “n × noise waveform cycle TN−target luminance value Y / reference signal change rate per unit clock”.
Next, in step S1605, the control unit 115 instructs shooting. Shooting is performed based on this instruction. The image to be taken may be a moving image or a still image.

Next, in step S1606, the control unit 115 determines whether or not the noise frequency has been changed. If the noise frequency is changed as a result of this determination, the process returns to step S1603, and the noise frequency is acquired again.
When there are a plurality of noise sources that affect the solid-state imaging device 300, the output start timing of the reference signal Vslop is reset according to the target noise frequency.
When the device to be driven for each shooting mode is determined, it may be determined that the noise frequency has been changed depending on whether the shooting mode has been changed. The noise information storage unit 1303 may have a noise frequency for each shooting mode in a table. For example, the switching frequency of the switching circuit at the time of strobe charging is stored in the noise information storage unit 1303 as a noise frequency, and this noise frequency is acquired in the strobe shooting mode. Also, for example, the PWM drive frequency of the drive coil of the lens for camera shake correction is stored in the noise information storage unit 1303 as a noise frequency, and this noise frequency is acquired in the still image shooting mode.

If the result of determination in step S1606 is that the noise frequency has not been changed, processing proceeds to step S1607 and the control unit 115 determines whether or not the target luminance value has been changed. If the target brightness value is changed as a result of this determination, the process returns to step S1602 to set the target brightness value again. If it is determined that the target luminance value has not been changed, the process proceeds to step S1608.
In step S1608, the control unit 115 determines whether the gain setting has been changed. If the gain is changed as a result of this determination, the process returns to step S1601 to set the gain again. On the other hand, if the gain has not been changed, the process advances to step S1609, and the control unit 115 determines whether or not shooting has been completed. If the result of this determination is that photography has not ended, processing returns to step S1605 and processing continues until photography ends.

  Such setting of the gain of the AD conversion circuit of the solid-state imaging device 300, setting of the target luminance value, and change of the output start timing of the reference voltage Vslop corresponding thereto are repeatedly performed until photographing is completed. As a result, the output timing of the reference voltage in accordance with the period of the noise waveform is dynamically set and changed according to the gain setting. Therefore, it is possible to suppress the noise from the noise source from being mixed into the image data output from the solid-state imaging device 300.

As described above, in the present embodiment, even if the gain of the AD conversion circuit of the solid-state imaging device 300 is changed, the P-phase output timing and the D-phase are set by setting the gain, noise frequency, and target luminance value. The output timing can be matched to the period of the noise waveform. Thereby, even when the gain is changed, the noise recorded in the photographed image can be easily and reliably reduced as described in the first to third embodiments.
Also in the present embodiment, various modifications described in the first to third embodiments can be employed.

  The above-described embodiments are merely examples of implementation in carrying out the present invention, and the technical scope of the present invention should not be construed in a limited manner. That is, the present invention can be implemented in various forms without departing from the technical idea or the main features thereof.

(Other examples)
The present invention is also realized by executing the following processing. That is, first, software (computer program) for realizing the functions of the above embodiments is supplied to a system or apparatus via a network or various storage media. Then, the computer (or CPU, MPU, etc.) of the system or apparatus reads and executes the computer program.

101 imaging optical system, 115 control unit, 300 solid-state imaging device

Claims (20)

A pixel unit configured by arranging a plurality of pixels each having photoelectric conversion means for photoelectrically converting incident light; and
Reading means for reading out a reset signal that is a signal when the potential of the pixel is reset from the pixel, and reading out an accumulated signal that is a signal accumulated in the pixel;
Timing control means for controlling the timing of the reading by the reading means, and a solid-state imaging device,
An imaging device that generates image data based on a signal read by the reading unit,
Frequency analysis means for performing frequency analysis on the image data;
A frequency deriving unit for deriving a switching operation frequency of a circuit including a transistor performing a switching operation based on the result of the frequency analysis by the frequency analyzing unit;
The interval between the signal readout timing when the pixel potential is reset and the readout timing of the signal accumulated in the pixel is determined so as to correspond to the switching operation frequency derived by the frequency deriving means. And an imaging device.   The frequency analysis unit performs frequency analysis on image data generated based on a signal obtained by the solid-state imaging device in a state where light input to the pixel is blocked. The imaging device described. The frequency analysis means performs frequency analysis for each of the image data obtained in different horizontal synchronization periods,
The frequency deriving means derives a switching operation frequency of the circuit based on a result of frequency analysis for each of the image data obtained in the plurality of different horizontal synchronization periods. The imaging device described in 1. A pixel unit configured by arranging a plurality of pixels each having photoelectric conversion means for photoelectrically converting incident light; and
Reading means for reading out a reset signal that is a signal when the potential of the pixel is reset from the pixel, and reading out an accumulated signal that is a signal accumulated in the pixel;
Timing control means for controlling the timing of the reading by the reading means, and a solid-state imaging device,
An imaging device that generates image data based on a signal read by the reading unit,
A plurality of lens driving means for driving the lenses at different driving frequencies;
Control means for determining an interval between the signal readout timing when the potential of the pixel is reset and the readout timing of the signal accumulated in the pixel so as to correspond to the least common multiple of the reciprocal of the different driving frequencies An imaging device comprising: A pixel unit configured by arranging a plurality of pixels each having photoelectric conversion means for photoelectrically converting incident light; and
Reading means for reading out a reset signal that is a signal when the potential of the pixel is reset from the pixel, and reading out an accumulated signal that is a signal accumulated in the pixel;
Timing control means for controlling the timing of the reading by the reading means, and a solid-state imaging device,
An imaging device that generates image data based on a signal read by the reading unit,
Lens driving means for driving the lens by changing the driving frequency of the lens over time;
Determining means for determining information relating to a current driving frequency of the lens;
The timing of reading the signal when the potential of the pixel is reset and the timing of reading the signal accumulated in the pixel so as to correspond to the driving frequency of the lens obtained from the information determined by the determining means And a control means for determining an interval between the imaging device and the image pickup apparatus. The readout means includes AD conversion means for converting the analog signal output from the pixel into a digital signal for each column of the pixels arranged in a matrix.
The imaging apparatus according to claim 1, wherein the analog signals output from the pixels arranged in the same row are converted into digital signals in parallel. The AD conversion means compares the analog signal output from the pixel with a reference signal whose value changes with time, and
Counting means for performing a counting operation until the value of the analog signal and the value of the reference signal are the same after the output of the reference signal is started;
For each column of pixels arranged in the matrix,
The interval is a timing at which the value of the analog reset signal and the value of the reference signal are the same; a timing at which the value of the analog accumulated signal and the value of the reference signal are the same; The imaging apparatus according to claim 6, wherein the imaging apparatus is an interval of A pixel unit configured by arranging a plurality of pixels each having photoelectric conversion means for photoelectrically converting incident light; and
Reading means for reading out a reset signal that is a signal when the potential of the pixel is reset from the pixel, and reading out an accumulated signal that is a signal accumulated in the pixel;
Timing control means for controlling the timing of the reading by the reading means, and a solid-state imaging device,
An imaging device that generates image data based on a signal read by the reading unit,
Control means for determining the timing of the reading controlled by the timing control means;
The readout means has AD conversion means for AD converting the analog signal output from the pixel into a digital signal,
The AD conversion means compares the analog signal output from the pixel with a reference signal whose value changes with time, and
Counting means for performing a counting operation until the value of the analog signal and the value of the reference signal are the same after the output of the reference signal is started,
The control means sets a gain in the AD conversion by changing a change amount of a value per unit time of the reference signal, and based on the set gain, the value of the analog reset signal, and the reference An image pickup apparatus characterized by determining an interval between a timing at which a signal value becomes the same, a timing at which the analog accumulated signal value and the reference signal value become the same. Gain information acquisition means for acquiring information relating to the gain;
Noise frequency information acquisition means for acquiring information related to the frequency of noise mixed in the signal;
Target luminance value acquisition means for acquiring information relating to the target luminance value of the image data,
Based on the information on the target luminance value, the information on the noise frequency, and the information on the gain, the control means determines whether the value of the analog reset signal and the value of the reference signal are The imaging apparatus according to claim 8, wherein an interval between the same timing and the timing at which the analog accumulated signal value and the reference signal value become the same is determined. The comparing means and the counting means are arranged for each column of pixels arranged in the matrix,
The imaging apparatus according to claim 8, wherein the AD conversion unit converts the analog signal output from the pixels arranged in the same row into a digital signal in parallel. A pixel unit configured by arranging a plurality of pixels each having photoelectric conversion means for photoelectrically converting incident light; and
Reading means for reading out a reset signal that is a signal when the potential of the pixel is reset from the pixel, and reading out an accumulated signal that is a signal accumulated in the pixel;
Timing control means for controlling the timing of the reading by the reading means, and a solid-state imaging device,
A method for controlling an imaging apparatus that generates image data based on a signal read by the reading unit,
A frequency analysis step for performing frequency analysis on the image data;
A frequency deriving step of deriving a switching operation frequency of a circuit including a transistor that performs a switching operation based on the result of the frequency analysis by the frequency analysis step;
The interval between the signal readout timing when the pixel potential is reset and the readout timing of the signal accumulated in the pixel is determined so as to correspond to the switching operation frequency derived by the frequency deriving step. A method for controlling the imaging apparatus.   The frequency analysis step performs frequency analysis on image data generated based on a signal obtained by the solid-state imaging device in a state where light input to the pixel is blocked. A control method for the imaging apparatus according to the description. The frequency analysis step performs frequency analysis for each of the image data obtained in different horizontal synchronization periods,
13. The frequency deriving step derives a switching operation frequency of the circuit based on a result of frequency analysis for each of the image data obtained in the plurality of different horizontal synchronization periods. The control method of the imaging device described in 1. A pixel unit configured by arranging a plurality of pixels each having photoelectric conversion means for photoelectrically converting incident light; and
Reading means for reading out a reset signal that is a signal when the potential of the pixel is reset from the pixel, and reading out an accumulated signal that is a signal accumulated in the pixel;
Timing control means for controlling the timing of the reading by the reading means, and a solid-state imaging device,
A method for controlling an imaging apparatus that generates image data based on a signal read by the reading unit,
A plurality of lens driving steps for driving the lenses at different driving frequencies;
A control step for determining an interval between a signal readout timing when the potential of the pixel is reset and a readout timing of the signal accumulated in the pixel so as to correspond to the least common multiple of the reciprocal of the different driving frequencies. And a method for controlling the imaging apparatus. A pixel unit configured by arranging a plurality of pixels each having photoelectric conversion means for photoelectrically converting incident light; and
Reading means for reading out a reset signal that is a signal when the potential of the pixel is reset from the pixel, and reading out an accumulated signal that is a signal accumulated in the pixel;
Timing control means for controlling the timing of the reading by the reading means, and a solid-state imaging device,
A method for controlling an imaging apparatus that generates image data based on a signal read by the reading unit,
A lens driving step of driving the lens by changing the driving frequency of the lens over time; and
Determining means for determining information relating to a current driving frequency of the lens;
The timing of reading the signal when the potential of the pixel is reset and the timing of reading the signal accumulated in the pixel so as to correspond to the driving frequency of the lens obtained from the information determined by the determining means And a control step of determining an interval between the imaging device and the imaging device. The readout step includes an AD conversion step of converting the analog signal output from the pixel into a digital signal for each column of pixels arranged in a matrix.
16. The method of controlling an imaging apparatus according to claim 11, wherein the analog signals output from the pixels arranged in the same row are converted into digital signals in parallel. . In the AD conversion step, for each column of pixels arranged in a matrix, a comparison step of comparing the analog signal output from the pixel with a reference signal whose value changes with time,
A counting step of performing a counting operation until the value of the analog signal and the value of the reference signal are the same after the output of the reference signal is started for each column of pixels arranged in a matrix And having
The interval is a timing at which the value of the analog reset signal and the value of the reference signal are the same; a timing at which the value of the analog accumulated signal and the value of the reference signal are the same; The image pickup apparatus control method according to claim 16, wherein the image pickup apparatus has an interval of A pixel unit configured by arranging a plurality of pixels each having photoelectric conversion means for photoelectrically converting incident light; and
Reading means for reading out a reset signal that is a signal when the potential of the pixel is reset from the pixel, and reading out an accumulated signal that is a signal accumulated in the pixel;
Timing control means for controlling the timing of the reading by the reading means, and a solid-state imaging device,
A method for controlling an imaging apparatus that generates image data based on a signal read by the reading unit,
A control step of determining the timing of the reading controlled by the timing control means;
The readout step includes an AD conversion step of AD converting the analog signal output from the pixel into a digital signal,
The AD conversion step compares the analog signal output from the pixel with a reference signal whose value changes with time, and
A counting step of performing a counting operation until the value of the analog signal is the same as the value of the reference signal after the output of the reference signal is started,
The control step sets a gain in the AD conversion by changing a change amount of a value per unit time of the reference signal, and based on the set gain, the value of the analog reset signal, and the reference An imaging apparatus control method, comprising: determining an interval between a timing at which a signal value is the same, a timing at which the analog accumulated signal value and the reference signal value are the same. A gain information acquisition step of acquiring information relating to the gain;
A noise frequency information acquisition step of acquiring information relating to a frequency of noise mixed in the signal;
A target luminance value acquisition step of acquiring information related to the target luminance value of the image data,
In the control step, the value of the analog reset signal and the value of the reference signal are based on information on the target luminance value, information on the frequency of the noise, and information on the gain. 19. The method of controlling an image pickup apparatus according to claim 18, wherein an interval between the same timing and a timing at which the analog accumulated signal value and the reference signal value become the same is determined. . In the comparison step, for each column of pixels arranged in a matrix, the analog signal output from the pixel is compared with a reference signal whose value changes over time,
The counting step counts until the value of the analog signal and the value of the reference signal become the same after the output of the reference signal is started for each column of pixels arranged in a matrix. Perform the action
The control of an imaging apparatus according to claim 18 or 19, wherein the AD conversion step converts the analog signal output from the pixels arranged in the same row into a digital signal in parallel. Method.

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