JP2001358994A - Image pickup area sensor and image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image pickup area sensor where charge storage timing differs from each pixel that senses flicker caused in a frame and eliminates the flicker. SOLUTION: The image pickup device of this invention is provided with the image pickup area sensor (1) that sequentially outputs signals by respective photoelectric conversion elements in a 1st mode, allows the photoelectric conversion elements of a line to start storage of electric charges at the same time, allows the photoelectric conversion elements of each line to start storage of electric charges at the same time, sums the stored electric charges of the photoelectric conversion elements at the same time and reads them, and sequentially outputs the summed signal of the respective lines in a 2nd mode, with a flicker detection means (5a) that detects flicker from the summed video signal of each line in the 2nd mode, and with a control means (5b) that sets the charge storage time of the image pickup area sensor to be a multiple of the period of flicker when the flicker is detected and activates the image pickup area sensor in the 1st mode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a MOS (Metal Ox
ide Semiconductor Device) area sensor and CMOS
(Complimentary Metal Oxide Semiconductor Device)
Regarding an imaging area sensor, such as an area sensor, in which charge accumulation timing at the time of imaging differs for each photoelectric conversion element and the charge accumulation time of the photoelectric conversion element can be adjusted, and an imaging device including the imaging area sensor, a commercial power supply ( When an object is imaged under illumination that is AC-lit at a frequency of 50 [Hz] or 60 [Hz], the above-described charge accumulation time is the AC lighting cycle (frequency 1/100 [s] or 1).
TECHNICAL FIELD The present invention relates to an imaging area sensor for detecting flicker generated when not synchronized with / 120 [Hz] and removing the flicker, and an imaging apparatus using the imaging area sensor.

[0002]

2. Description of the Related Art FIG. 15 shows a CCD (Charge Coupled Device).
e) is a configuration diagram of a conventional imaging device including an area sensor. In FIG. 15, 13 is a CCD imaging area sensor,
14 is a pre-signal processing means, 15 is a gain adjusting means, 16 is a signal processing means, 17 is a first integrating means, 18 is a second integrating means, 19 is a third integrating means, 20 is an iris, 21
Is an iris driver, 22 is a timing generator (TG), and 23 is a calculating means.

[0005] The operation of the conventional imaging apparatus shown in FIG. 15 will be described below. The iris 20 is a CCD area sensor 1
3. Control the amount of light condensed on 3 (perform exposure control).
The CCD area sensor 13 is operated by a driving pulse output from the TG 22, converts an incident light image into an electric signal, and outputs the electric signal to the front signal processing unit 14 as an image pickup signal.

FIG. 16 is a principle diagram of the CCD area sensor 13. The CCD area sensor 13 includes a plurality of photoelectric conversion elements (PD: Photo Diode) 24 arranged two-dimensionally,
A plurality of CCD vertical registers 25 and a CCD horizontal register 26 are provided for each column of the PD 24.

[0005] The PD 24 accumulates electric charges generated according to the amount of incident light for a predetermined time, transfers the electric charges to the corresponding CCD vertical register 25, and then starts electric charge accumulation again.
All PDs 24 simultaneously start accumulating electric charges, and simultaneously transfer the accumulated electric charges to the CCD vertical register 25 as a signal amount. Therefore, in the CCD area sensor 13, the charge accumulation time and the charge accumulation timing of all PDs 24 are the same.

The electric charge transferred from the PD 24 to the CCD vertical register 25 is transferred by the CCD vertical register 25 as shown in FIG.
The data is transferred in the vertical direction as indicated by an arrow 6 and reaches the CCD horizontal register 26, is transferred in the horizontal direction by the CCD horizontal register 26, and is output as an image pickup signal. Since the CCD vertical register 25 and the CCD horizontal register 26 are completely shielded from light, the CCD area sensor 13
The charge accumulation time and charge accumulation timing of all PDs 24 can be made the same.

As described above, the CCD area sensor 13 is
By accumulating the electric charge for each electric charge accumulation time, one frame (corresponding to one imaged image) is taken every frame period. In the CCD area sensor 13, the above-described charge accumulation time is the same as the frame period (the time interval for imaging one frame), except for the case where the electronic shutter described later is caused to function. Note that, since the above-mentioned frame corresponds to a captured image, NTSC (Na
(National Television System Committee). The above frame corresponds to a field in the NTSC video signal. Therefore, the above-mentioned frame period is set to NTSC (National Television Sy
In the stem committee) method, it is 1/60 [s].

In FIG. 15, the pre-signal processing means 14
Removes noise from the image pickup signal of the CCD area sensor 13 by processing such as correlated double sampling, and sends it to the gain control means 15 and the first integration means 17 as a video signal. The first integrating means 17 integrates the video signal from the pre-signal processing means 14 for each frame or every several frames, sends a control signal to the iris driver 21 so that the integrated value is constant, and Open and close.

The gain adjusting means 15 includes the pre-signal processing means 1
4 is amplified and sent to the signal processing means 16, the second integrating means 18, and the third integrating means 19. The signal processing means 16 performs signal processing such as image quality adjustment processing (for example, white balance adjustment, gamma correction, enhancement correction (contour correction), etc.) and conversion processing on the video signal input from the gain adjustment means 15, Encode to get the required signal format. Second integrating means 18
Accumulates the video signal from the gain adjusting means 15 every one frame or every several frames, and adjusts the signal gain of the gain adjusting means 15 so that the integrated value becomes constant. Normally, the level of the video signal input to the gain adjusting means 15 is previously adjusted to a constant level by exposure control by the iris 20, so that the signal gain of the gain adjusting means 15 is also constant, but the illuminance of the subject is low. When the required exposure amount cannot be obtained even when the iris 20 is fully opened, the video signal is amplified by the gain adjusting means 15 so that a video signal of a constant level is obtained.

The third integrating means 19 is provided for detecting flicker. The third integrating means 19 integrates the video signal for each frame and outputs the integrated value to the calculating means 23. The calculating means 23 detects whether or not flicker has occurred based on the above integrated value, and when detecting flicker, sends a control signal to the TG 22 to change the charge accumulation time of the CCD area sensor 13; Reduces flicker.

The procedure for detecting flicker will be described below.
FIG. 17 is a view for explaining the principle of generating flicker in the CCD area sensor 13. The frequency of illumination such as a fluorescent lamp that is AC-lit by a commercial power supply is twice the commercial frequency as shown in FIG. That is, the commercial frequency is 50 [Hz]
In this case, the lighting frequency is 100 [Hz], and the AC lighting cycle (interval time between AC lighting) is 1/100 [s]. When the commercial frequency is 60 [Hz], the lighting frequency is 120 [Hz], and the AC lighting cycle is 1/12.
0 [s]. FIG. 17 shows a commercial frequency of 50 [Hz].
3 shows a case where an image is captured in a charge accumulation time of 1/60 [s] under the illumination of FIG. The charge accumulation time is between a and b and cd in FIG. At b, the accumulated charges are transferred, and charge accumulation of the next frame is started from c. At this time, the amount of illumination light between a and b and between c and b (the area of the shaded portion in FIG. 17) is different. Therefore, the brightness differs between the captured images between a and b and between c and b. Therefore, an image pickup signal having a different signal level is generated for each frame, and flicker occurs. 1 under illumination of AC lighting frequency 100 [Hz]
20 [H] when the image is captured in the charge accumulation time of / 60 [s]
z] flicker occurs.

The calculating means 23 calculates the above 20 [H] from the integrated value of the video signal for each frame by the third integrating means 19.
When the frequency component of z] is detected, it is determined that flicker has occurred.

In the image pickup apparatus shown in FIG. 15, the time constant of the feedback for controlling the iris 20 from the first integrating means 17 and the time constant of the feedback for controlling the gain adjusting means 15 from the second integrating means 18 are hunting (oscillation). For prevention, it is set sufficiently longer than the above 20 [Hz]. For this reason, it is difficult to sufficiently suppress flicker by the above-mentioned feedback means. Therefore,
In the imaging device of FIG. 15, flicker is suppressed as follows.

When the calculation means 23 determines that flicker has occurred, it sends a control signal to the TG 22 to change the charge accumulation time of the CCD area sensor 13 by the TG 22. When the flicker of 20 [Hz] is detected, the charge accumulation time is changed to 1/100 [s]. CC
The D area sensor 13 has a function of an electronic shutter that changes the charge storage time by discharging the stored charges of all PDs 24 once at the same time during the charge storage and then starting the charge storage again. TG22
When the above control signal is input from the calculating means 23,
The above-mentioned electronic shutter is operated to reduce the charge storage time to 1/1.
The drive pulse for setting the speed to 00 [s] is applied to the CCD area sensor 13
Output to Thus, the charge accumulation time of the CCD area sensor 13 is changed to 1/100 [s] as shown in FIG. In the charge storage time of 1/100 [s], the light quantity between a and b and cd in FIG. 18 is the same, so that flicker does not occur.

As described above, in an image pickup apparatus using a CCD area sensor, flicker is detected from an integrated value of one frame of a video signal, and when flicker occurs,
The charge storage time is determined by the AC lighting cycle (1/100 [s])
Alternatively, flicker can be suppressed by synchronizing with flicker.

However, in recent years, mobile applications for low power consumption (PDA: Personal Digital Assistants)
Is not the above CCD area sensor,
An imaging area sensor called a CMOS area sensor or a MOS area sensor is often used. The CMOS area sensor and the MOS area sensor are different from the CCD area sensor in that the timing of charge accumulation differs for each photoelectric conversion element. Therefore, the flicker detection method and the suppression method of the CCD area sensor described above use the flicker detection and suppression methods. Can't suppress.

The principle of the CMOS area sensor will be described.
The same applies to the principle of the MOS area sensor. FIG.
1 is a configuration diagram of a CMOS area sensor. In FIG. 19, 1a, 1b, 1c, 1d are photoelectric conversion elements (PD),
1e, 1f, 1g, 1h are amplifiers, 1i, 1j, 1k,
1m is a pixel selection transistor, 1n and 1p are column selection transistors, 1q is a vertical shift register, 1y is a horizontal shift register, 1s is an output terminal of an imaging signal, 1z is a drive pulse generating means, 1u, 1v, 1w, and 1x are reset. The circuit 10 is a CMOS area sensor.

The area sensor 10 shown in FIG. 19 has M × N PDs (1a, 1b, 1c, M, N are integers of 3 or more).
1d,...) And M × N amplifiers (1e, 1f, 1g,
1h,...) And M × N reset circuits (1u, 1v,
1w, 1x,...), M × N pixel selection transistors (1i, 1j, 1k, 1m,...), N column selection transistors (1n, 1p,.
z, a vertical shift register 1q, a horizontal shift register 1y, and an output terminal 1s. In the area sensor of FIG. 19, the PD 1a, the amplifier 1e, the reset circuit 1u, and the pixel selection transistor 1i constitute one pixel. The area sensor 10 includes M × N pixels having the above configuration. PD1a, 1b,
1c, 1d,... Generate charges corresponding to the amount of incident light. These charges are accumulated in the capacitance between the PDs 1a, 1b, 1c, 1d,... And the amplifiers 1e, 1f, 1g, 1h,.
The vertical shift register 1q includes the pixel selection transistor 1
select ON / OFF of i, 1j, 1k, 1m,..., and the horizontal shift register 1y includes column selection transistors 1n, 1
Select ON / OFF of p, ... The drive pulse generating means 1z outputs a drive pulse to the vertical shift register 1q and the horizontal shift register 1y, and controls an operation of reading an image signal by the electric charge accumulated in the PD and a reset operation of the PD.

The area sensor 10 configured as described above
In this case, the PDs 1a, 1 are arranged by the horizontal shift register 1y and the vertical shift register 1q in the order of arrows in FIG.
b,..., 1c, 1d,.
Are sequentially read out as imaging signals, and the output terminal 1
Output from s. For example, the vertical shift register 1q controls the pixel selection transistors 1i, 1j,.
Is turned on, and the column shift transistor 1n in the first column is turned on by the horizontal shift register 1y, so that the charge in the PD1a in the first column of the first line is read out via the transistors 1i and 1n.

In the area sensor 10, the readout timing differs for each PD as described above. However, in order to make the charge accumulation time of all PDs the same, a horizontal shift register 1y and a vertical shift register 1q are used. The reset circuits 1u, 1v,.
.., 1c, 1d,... are sequentially reset by the selected reset circuit, and charge accumulation is sequentially started at different timings for each PD.

The above CMOS area sensor 10 and MOS
In an imaging device including an imaging area sensor having different charge accumulation timings for each PD, such as an area sensor, unlike a CCD area sensor in which the charge accumulation timings of all PDs are the same, flicker is as follows. Occurs.

FIG. 21 is a diagram for explaining the principle of generating flicker in the area sensor 10. Area sensor 1
In the case of 0, as described above, the charge accumulation timing differs for each pixel, and therefore the charge accumulation start timing and the completion timing of each line (row) of the area sensor 10 also differ as shown in FIG. Therefore, the image signal has a different signal level for each line as shown in FIG. As a result, as shown in FIG. 23, the luminance becomes uneven in the vertical direction within one frame image, and flicker appears. In FIG. 23, the part A is a low luminance part, and the part B is a high luminance part.

[0023]

As described above, in a conventional image pickup apparatus having an image pickup area sensor such as a CMOS area sensor or a MOS area sensor in which the charge accumulation timing differs for each pixel, the AC lighting frequency of the illumination, If the charge accumulation time of the area sensor is not synchronized, FIG.
Flicker occurs as luminance unevenness in a frame as shown in FIG.

However, in an image pickup apparatus using an image pickup area sensor whose charge accumulation timing differs for each pixel, flicker occurs as uneven brightness in a frame. Therefore, unlike an image pickup apparatus using a CCD area sensor, a flicker occurs. There is a problem that the flicker cannot be detected from the integrated value for each frame.

The present invention has been made in order to solve such a conventional problem, and it is possible to detect flicker occurring in a frame in an imaging area sensor in which charge accumulation timing differs for each pixel, and remove the flicker. It is an object of the present invention to provide an imaging area sensor and an imaging device that can perform the imaging.

[0026]

According to a first aspect of the present invention, there is provided an imaging area sensor for individually resetting photoelectric conversion elements and starting charge accumulation, and a photoelectric conversion element. Readout means for individually reading out the charges accumulated in the elements and outputting the readouts to the outside; driving means for driving the reset means and the readout means to control the start timing and the readout timing of the charge accumulation of each photoelectric conversion element; and Wherein the charge accumulation timing at the time of imaging is different for each photoelectric conversion element and the charge storage time of the photoelectric conversion element can be adjusted. In the imaging area sensor, when the driving unit is in the first mode, The charge accumulation is started sequentially, the accumulated charges are sequentially read, and the signals from the respective photoelectric conversion elements are sequentially output, and In the mode, the charge accumulation of a plurality of photoelectric conversion elements on the same line (including all photoelectric conversion elements on the same line) is started simultaneously, and the charge accumulation is sequentially started for each line. It is characterized in that the electric charges accumulated in the elements are added simultaneously and read out, and the added signals of the respective lines are sequentially output.

According to a second aspect of the present invention, there is provided an imaging apparatus comprising: an imaging area sensor according to the first aspect; and a video signal added for each line by the imaging area sensor when operated in the second mode. When the flicker detecting means for detecting flicker and the imaging area sensor are operated in the second mode, and when flicker is detected, the charge accumulation time of the imaging area sensor is set to a multiple of a flicker cycle (including the flicker cycle). ), And control means for operating the imaging area sensor in the first mode.

According to a third aspect of the present invention, in the image pickup apparatus, the flicker detecting means detects a flicker frequency component from the video signal in the second mode, and a signal level of the flicker frequency component. Comparing means for comparing with a set reference value, wherein when the flicker frequency component is larger than the reference value, flicker is detected.

According to a fourth aspect of the present invention, in the image pickup apparatus, the first flicker detecting means detects a first frequency component which is a flicker frequency component from the video signal in the second mode. A second frequency detecting means for detecting a second frequency component which is not a flicker frequency component from the image signal, and a comparing means for comparing a signal level of the first frequency component with a signal level of the second frequency component. A flicker is detected when the first frequency component is larger than the second frequency component by a predetermined value or more.

According to a fifth aspect of the present invention, in the image pickup apparatus, the flicker detecting means detects a first flicker frequency component from the video signal in the second mode, and the video signal A second frequency detecting means for detecting a second flicker frequency component from the first signal, a first comparing means for comparing a signal level of the first flicker frequency component with a preset reference value, A second comparing means for comparing the signal level of the frequency component with the reference value, wherein when the first flicker frequency component is larger than the reference value, the flicker of the first frequency is detected; When the second flicker frequency component is larger than the reference value, flicker of the second frequency is detected.

According to a sixth aspect of the present invention, in the imaging apparatus, the frequency detecting means includes a band-pass filter that allows only a flicker frequency component to pass, and an integrating means that integrates an output signal of the band-pass filter. Features.

According to a seventh aspect of the present invention, there is provided an image pickup apparatus, comprising: a gain adjusting means for adjusting a gain of a video signal by the imaging area sensor; an integrating means for integrating the gain-adjusted video signal; Signal level determining means for determining whether the integrated value is within a predetermined range,
The control means controls the charge accumulation time and the signal gain of the gain adjustment means so that the integrated value of the video signal is within the predetermined range in the imaging operation in the first mode when flicker is detected. Is controlled.

The image pickup apparatus according to claim 8 of the present invention provides a look-up table listing combinations of charge accumulation times and signal gains that can be set in an image pickup operation in the first mode when flicker is detected. Further comprising
The control means controls the charge accumulation time and the signal gain with reference to the look-up table in the imaging operation in the first mode when flicker is detected.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a configuration diagram of an imaging device according to Embodiment 1 of the present invention. In FIG.
1 is an area sensor (imaging area sensor), 2 is a pre-signal processing means, 3 is a gain adjusting means, 4 is an A / D converter,
5 is a computing means, 5a is a flicker detecting means, 5b is a control means, 5c is a specific frequency detecting means, 5d is a comparing means,
e is reference value setting means, 5h is LUT (Look Up Tabl)
e) 5i is a signal level detecting means, 6 is an integrating means, 7 is an output terminal, and 8 is a signal processing means.

[Area Sensor 1] The area sensor 1 is a CMOS area sensor that captures an incident light image, converts it into an electric signal, and outputs this captured signal to the pre-signal processing means 2. FIG. 2 is a configuration diagram of the area sensor 1. In FIG. 2, the same components as those in FIG.
a, 1b, 1c, 1d are photoelectric conversion elements (PD), 1e,
1f, 1g, 1h are amplifiers, 1i, 1j, 1k, 1m are pixel selection transistors, 1n, 1p are column selection transistors, 1q is a vertical shift register, 1r is a horizontal shift register, 1s is an image signal output terminal, and 1t is Drive pulse generating means, 1u, 1v, 1w, and 1x are reset circuits.

The area sensor 1 according to the first embodiment shown in FIG.
In the conventional CMOS area sensor shown in FIG. 19, the horizontal shift register 1y and the drive pulse generator 1z are respectively a horizontal shift register 1r and a drive pulse generator 1t. The operation is performed in a flicker detection mode in which the charges of all PDs on the same line are added and read at the same time, and the added charges are sequentially read line by line. In the imaging mode, the charge accumulation timing differs for each PD, but in the flicker detection mode, the charge accumulation timing of all PDs on the same line is the same, and the charge accumulation timing differs for each line.

As shown in FIG. 2, the area sensor 1 of the first embodiment has M × N (M and N are integers of 3 or more) PDs (1
a, 1b, 1c, 1d,...) and M × N amplifiers (1
, 1f, 1g, 1h,...), M × N reset circuits (1u, 1v, 1w, 1x,...), and M × N pixel selection transistors (1i, 1j, 1k, 1m,. )When,
It includes N column selection transistors (1n, 1p,...), Drive pulse generation means 1t, a vertical shift register 1q, a horizontal shift register 1r, and an output terminal 1s.

Each of the PDs 1a, 1b, 1c, 1d,... Accumulates a charge corresponding to the amount of incident light during the charge accumulation time. The amplifiers 1e, 1f, 1g, 1h,... Amplify (convert the charges into voltage signals) the signals based on the charges accumulated in the PDs 1a, 1b, 1c, 1d,. The reset circuits 1u, 1v, 1w, 1x,.
Are reset (the charge accumulated in the PD is discarded), and the charge accumulation is started. The reset timing by this reset circuit becomes the charge accumulation start timing of the PD. The charge accumulation time of the PD is from the charge accumulation start timing (reset timing) to the charge readout timing. The charge accumulation start timing differs for each PD in the imaging mode.
In the flicker detection mode, although different for each line, the charge accumulation time is the same for all PDs.

The horizontal shift register 1r sequentially selects columns in the imaging mode in accordance with the driving pulse from the driving pulse generating means 1t, turns on the column selection transistor (1n or 1p) of the selected column, and in the flicker detection mode. , All the column selection transistors (1n and 1p) are simultaneously turned on. The vertical shift register 1q sequentially selects one line according to the driving pulse from the driving pulse generating means 1t, and all the pixel selection transistors (1i and 1j, or 1g and 1h) of the selected line.
Is turned on. In the imaging mode, the horizontal shift register 1r and the vertical shift register 1q sequentially select one reset circuit in accordance with the driving pulse from the driving pulse generating means 1t, and the selected reset circuit selects P.
D is sequentially reset, and in the flicker detection mode, all reset circuits of the same line are simultaneously selected, and reset circuits of different lines are sequentially selected. Reset.

The drive pulse generating means 1t supplies a drive pulse to the horizontal shift register 1r and the vertical shift register 1q in accordance with the control signal from the arithmetic means 5, and operates the area sensor 1 in the imaging mode or the flicker detection mode. The drive pulse generator 1t adjusts the charge accumulation time of the PD by adjusting the reset timing of the PD with respect to the read timing.

As described above, in the area sensor 1 of the first embodiment, the charge accumulation timing at the time of imaging differs for each photoelectric conversion element, and the charge accumulation time of the photoelectric conversion element can be adjusted.
In the MOS imaging area sensor, charge accumulation is sequentially started at different timings for each photoelectric conversion element, and the charges accumulated in each photoelectric conversion element are sequentially read out individually.
In addition to the imaging mode (first mode) in which the photoelectric conversion elements are sequentially output as imaging signals, the charge accumulation of all photoelectric conversion elements on the same line is started simultaneously, and the charge accumulation is started at a different timing for each line. Let
The operation is performed in a flicker detection mode (second mode) in which charges accumulated in the plurality of photoelectric conversion elements are simultaneously read out and added, and the added charges are sequentially output as imaging signals of respective lines in a line-by-line manner. Things.

[Pre-signal processing means 2, gain adjustment means 3,
A / D Converter 4] In FIG. 1, the pre-signal processing means 2 removes noise such as switching noise of a transistor included in the image signal input from the area sensor 1 and sends it to the gain adjusting means 3. The gain control unit 3 converts the video signal input from the pre-signal processing unit 2 into an arithmetic unit 5
And amplifies the signal with a signal gain corresponding to the control signal from the A / D converter 4. The A / D converter 4 converts the analog video signal input from the gain control unit 3 into a digital signal, and (the flicker detection unit 5 of the arithmetic unit 5).
a), is sent to the integrating means 6 and the signal processing means 8.

[Integrating means 6, signal processing means 8] The integrating means 6 integrates the video signal every frame or every several frames, and sends the integrated value of the video signal to the calculating means 5 (signal level detecting means 5i). . The signal processing unit 8 performs signal processing such as image quality adjustment processing and conversion processing on the video signal input from the A / D converter 4, encodes the video signal into a video signal of a required format, and outputs the video signal from the output terminal 7. For example, it adjusts the white balance of the input video signal, performs image quality adjustment such as gamma correction and enhancement correction (contour correction), encodes the video signal into a required format video signal, and outputs the video signal from the output terminal 7.

[Calculating means 5] The calculating means 5 includes a flicker detecting means 5a, a control means 5b, and an LUT (Look Up Ta).
ble) 5h and signal level detecting means 5i.

[Flicker detecting means 5a] The flicker detecting means 5a is used in the flicker detecting mode on the basis of the video signal added from the A / D converter 4 of the signal processing means and added for each line. Is detected, and the detection result is sent to the control means 5b.
This flicker detection means 5a is, for example, as shown in FIG.
It comprises a specific frequency detecting means 5c, a comparing means 5d, and a reference value setting means 5e.

[Specific Frequency Detecting Means 5c] The specific frequency detecting means 5c detects only a flicker frequency component (a frequency component included in the video signal when flicker occurs) from the video signal added for each line. The frequency component is sent to the comparison means 5d. The flicker frequency component described above is 1 under illumination of a commercial frequency of 50 [Hz].
00 [Hz] and a commercial frequency of 60 [H
Under the illumination of [z], the frequency component is 120 [Hz].

The specific frequency detecting means 5c can be realized by a BPF (Band Pass Filter) 5f and an integrating means 5g as shown in FIG. 3, for example. The BPF 5f converts a flicker frequency component (100 [H
z] or only the frequency component of 120 [Hz] is passed and sent to the integrating means 5g. The integrating means 5g integrates the flicker frequency component for one frame period, for example, and sends the integrated value of the flicker frequency component to the comparing means 5d.

[Reference value setting means 5e, comparison means 5d] The reference value setting means 5e supplies a reference value set in advance to the comparison means 5d. The comparing means 5d compares the value of the flicker frequency component detected by the specific frequency detecting means 5c with the reference value. If the flicker frequency component is larger than the reference value, it is assumed that flicker has been detected, and the flicker frequency component is detected. Is smaller than the reference value, it is determined that flicker has not been detected, and the detection result is sent to the control unit 5b.

[Signal Level Detecting Means 5i] The signal level detecting means 5i determines whether or not the integrated value of the video signal input from the integrating means 6 is within a preset reference value range. The level of the video signal is detected, and the detection result is sent to the control unit 5b.

[Control Unit 5b] The control unit 5b controls the operation mode (image pickup mode or flicker detection mode) of the area sensor 1 and the charge accumulation time, and also controls the signal gain of the gain adjustment unit 3. This control means 5b
Operates the area sensor 1 in the flicker detection mode, detects whether or not flicker is generated by the flicker detection means 5a, and then switches the area sensor 1 to the imaging mode. If there is no flicker,
In the imaging mode, the control unit 5b adjusts the level of the video signal within a predetermined range by continuously adjusting the charge accumulation time according to the detection result of the video signal level by the signal level detection unit 5i. The signal level is adjusted by adjusting the signal gain of the gain adjusting means 3 only when the signal level cannot be adjusted with time. In the imaging mode after flicker is detected, the control means 5b sets the charge accumulation time of the area sensor 1 to a multiple (including the flicker cycle) of the flicker cycle (= AC lighting cycle by commercial power supply), and The signal level is adjusted by adjusting the signal gain of the gain adjusting means 3.

[LUT5h] In the LUT5h, a combination of a set value of the charge accumulation time of the area sensor 1 and a set value of the signal gain of the gain adjusting means 3 in the imaging mode after the flicker is detected is tabulated in advance. In the imaging mode after flicker is detected, the control unit 5b refers to the LUT 5h and sets the charge accumulation time of the area sensor 1 and the signal gain of the gain adjustment unit 3,
The charge accumulation time and the signal gain are changed according to the level of the detected video signal.

[Operation of Area Sensor 1 in Imaging Mode]
The operation of the area sensor 1 in the imaging mode will be described below with reference to FIG. Drive pulse generating means 1t
When the control signal for operating in the imaging mode is input from the control means 5b of the arithmetic means 5, the horizontal shift register 1
r and the vertical shift register 1q to operate the area sensor 1 in the imaging mode as described below.

Assuming that the time (timing) is t and the timing at which the PD 1a in the first column of the first line is reset to start charge accumulation is t = 0, in the imaging mode, t =
At ΔT (> 0), the PD 1b is reset to start charge accumulation, and thereafter, t = 2ΔT, 3ΔT,..., (N−1)
At ΔT, PDs in the third and subsequent columns of the first line are sequentially reset. At t = NΔT, PD1c in the first column of the second line is reset. At t = (N + 1) ΔT, PD1d is reset. (N + 2) ΔT,
(N + 3) ΔT,..., (2N−1) ΔT, 2NΔT,
.., (MN−1) ΔT, from the third column of the second line to
The PDs in the Nth column of the Mth line are sequentially reset. First
The PD1a in the first column of the line is reset again
This is after the PD in the Nth column of the Mth line has been reset.

Here, the frame period of the video signal is Tf,
If the charge accumulation time in the imaging mode of the area sensor 1 (the same time in all PDs) is T, then M × N × ΔTa ≦ Tf T ≦ Tf.

The following read operation is performed together with the above reset operation. First, when t = T, the pixel selection transistors 1i, 1j,... Of the first line are turned on, the column selection transistor 1n is turned on, and t = 0 to t.
= T, an imaging signal based on the electric charge accumulated in the PD 1a is read out, output from the output terminal 1s via the transistors 1i and 1n, and thereafter, the column selection transistor 1
n turns off. Next, when t = ΔT + T, the column selection transistor 1p is turned on, and an imaging signal due to the electric charge accumulated in the PD 1b during t = ΔT to t = ΔT + T is read out and output via the transistors 1j and 1p. ,
The column selection transistor 1p turns off. Hereinafter, similarly, t = 2ΔT + T, 3ΔT + T,..., (N−1)
In ΔT + T, PDs in the third to Nth columns of the first line
Are sequentially read out, and after the image pickup signals of the PDs in the Nth column are read out, the pixel selection transistors 1i, 1j,... Of the first line are turned off.

Next, when t = NΔT + T, the pixel selection transistors 1k, 1m,... Of the second line are turned on, the column selection transistor 1n is turned on, and t = N × Δ
During the period from T to t = NΔT + T, the imaging signal based on the electric charge stored in the PD 1c is read, and the column selection transistor 1n is turned off. Next, when t = (N + 1) ΔT + T,
The column selection transistor 1p is turned on, and the time t = (N + 1)
During the time period ΔT to t = (N + 1) ΔT + T, the imaging signal due to the charge accumulated in the PD 1d is read, and the column selection transistor 1p is turned off. Hereinafter, in the same manner, t =
(N + 2) ΔT + T, (N + 3) ΔT + T,..., (2N
−1) ΔT + T, 2NΔT + T,..., (MN−1) ΔT
+ T, the third column of the second line to the Nth line of the Mth line
The imaging signals of the PDs in the column are sequentially read. The reason why the image pickup signal of the PD1a in the first column of the first line is read again is as follows.
This is after the imaging signal of the PD in the Nth column of the Mth line is read. Thus, in the imaging mode, M × N PDs 1a, 1b, 1c, 1d,
Are sequentially read out and output.

[Operation of Area Sensor 1 in Flicker Detection Mode] The operation of the area sensor 1 in the flicker detection mode will be described below with reference to FIG. When a control signal for operating in the flicker detection mode is input from the control unit 5b of the arithmetic unit 5, the drive pulse generation unit 1t controls the horizontal shift register 1r and the vertical shift register 1q, and sets the area sensor 1 to Operate in imaging mode as described.

When the time (timing) is t, and the timing at which the N PDs 1a, 1b,... Of the first line are simultaneously reset to start charge accumulation is t = 0, in the flicker detection mode, t = ΔU ( > 0), the second
.. Of the line are simultaneously reset to start charge accumulation, and thereafter, t = 2Δ
In U, 3ΔU,..., (M−1) ΔU, the N PDs in the third to Mth lines are sequentially reset. First
The line PDs 1a, 1b,... Are reset again after the M-th line PD is reset.

In addition to the above-described reset operation for simultaneously resetting all PDs on the same line, the following read operation is performed in which the image pickup signals of all PDs on the same line are added and output as an image pickup signal for each line. The charge storage time of the area sensor 1 in the flicker detection mode (all P
U is the same time in D). First, when t = U, the pixel selection transistors 1i, 1j,.
Is turned on, and all the column selection transistors 1n,
Are turned on, and the imaging signals of the N PDs 1a, 1b,... On the first line due to the charges accumulated during t = 0 to t = U are simultaneously displayed as indicated by the bold arrows in FIG. The added and read out signal is output to the output terminal 1s as an image signal of the first line.
From the pixel selection transistors 1i, 1
j,... and the column selection transistors 1n, 1p,.
F.

Next, when t = ΔU + U, the pixel selection transistors 1k, 1m,... Of the second line are turned on, and all the column selection transistors 1n, 1p,.
The imaging signals of the N PDs 1c, 1d,... Of the second line due to the charges accumulated during t = ΔU to t = ΔU + U are simultaneously added and read out, and output as the imaging signal of the second line. Are output from the terminal 1s, and then the pixel selection transistors 1k, 1m,.
.. are turned off.

Hereinafter, similarly, t = 2ΔU + U,
At 3ΔU + U,..., (M−1) ΔU + T, the imaging signals of the N PDs on the third line to the Mth line are simultaneously added and sequentially read out, and output terminals are output as the imaging signals of the third line to the Mth line. It is sequentially output from 1s.

Here, the charge storage time U in the flicker detection mode is the same as the charge storage time T in the imaging mode, for example. The above ΔU is the output time interval of the added image signal for each line, and the above ΔU is the output time interval of the image signal for each PD in the imaging mode.
Using T, for example, ΔU = NΔT. The charge accumulation time U in the flicker detection mode needs to be not a multiple (including the AC lighting cycle) of the AC lighting cycle by the commercial power supply in order to detect flicker. That is, it is necessary that the AC lighting cycle is not a multiple of 1/100 [s] under the illumination of the commercial frequency 50 [Hz], and the AC lighting cycle 1/12 under the illumination of the commercial frequency 60 [Hz].
It must be not a multiple of 0 [s]. Further, for example, U = T / N and ΔU = ΔT, and the frame period Tf can be reduced to 1 / N in the imaging mode.

[Pre-signal processing means 2, gain adjustment means 3,
Operation of A / D Converter 4] The imaging signal output from the area sensor 1 in the imaging mode or the flicker detection mode is subjected to pre-signal processing means 2 in which noise such as switching noise of the transistor of the area sensor 1 is removed, and the image is displayed. The signal is sent to the gain adjusting means 3, amplified by the gain adjusting means 3, sent to the A / D converter 4, converted into a digital signal by the A / D converter 4, and flicker detecting means 5 a (flicker detecting In the case of the mode), it is sent to the integrating means 6 and the signal processing means 8.

[Operation of Signal Processing Means 8 and Integrating Means 6]
The image signal is subjected to signal processing such as image quality adjustment processing (for example, white balance adjustment, gamma correction, enhancement correction, etc.) and conversion processing, is encoded into a video signal of a required format, and is output from the output terminal 7. The integrating means 6 integrates the video signal by one frame or several frames, and sends the integrated value to the calculating means 5.

[Flicker detection operation] Control means 5b
First, the drive pulse generating means 1t of the area sensor 1
Then, a control signal for operating in the flicker detection mode is sent to operate the area sensor 1 in the flicker detection mode. The imaging signal output from the area sensor 1 and added for each line is converted to a digital signal in the A / D converter 4 via the pre-signal processing means 2 and the gain adjusting means 3 and the flicker detecting means 5a is specified. It is input to the frequency detecting means 5c.

When flicker occurs in the area sensor 1, a component having the same frequency as the AC lighting frequency of the illumination is included in the image signal. Hereinafter, this frequency component is called a flicker frequency. That is, the commercial frequency 50 [Hz]
Since the AC lighting frequency of the lighting is 100 [Hz],
When flicker occurs under this illumination, 1
A flicker frequency component of 00 [Hz] is included. In addition, since the alternating-current lighting frequency of the commercial frequency 60 [Hz] illumination is 120 [Hz], when flicker occurs under this illumination, the imaging signal includes a 120 [Hz] flicker frequency component.

The flicker detecting means 5a detects the flicker frequency component from the video signal added for each input line, and determines whether or not flicker has occurred based on the magnitude of the flicker frequency component. Determine.
In the flicker detecting means 5a, the BPF 5f of the specific frequency detecting means 5c outputs the flicker frequency component (100 [Hz] or 120 [H]) contained in the video signal.
z]), and sends this flicker frequency component to the integrating means 5g. The integrating means 5g integrates the flicker frequency component for each frame, and sends the integrated value of the flicker frequency component to the comparing means 5d. If flicker occurs, the integrated value of the flicker frequency component becomes large. The comparing means 5d compares the integrated value of the flicker frequency component with the reference value of the reference value setting means 5e. If the integrated value is larger than the reference value, it is assumed that flicker has been detected. Is smaller than the reference value, it is determined that flicker has not been detected, and the detection result is sent to the control unit 1b.

FIG. 4 is a waveform diagram of a flicker frequency component included in an image pickup signal by M PDs in a certain column in the area sensor 1. In FIG. 4, the column direction of the area sensor 1 is the Y direction, and the scanning lines of the area sensor 1 are indicated by arrows. Further, the Y axis in the waveform diagram of FIG. 4 is also a time axis. The flicker frequency component in FIG.
Under illumination of a commercial frequency of [Hz], the frequency is 100 [H].
z], and becomes a signal with a frequency of 120 [Hz] under illumination of a commercial frequency of 60 [Hz].

In the imaging mode, since the charge accumulation timing is different for each column, the imaging signals from the PDs in different columns (for example, the imaging signals from the M PDs in the first column,
In the image signals by the M PDs in the center row), the phases of the flicker frequency components in FIG. 4 included in these video signals are different. For this reason, the video signal output from the area sensor 1 in the imaging mode or the video signal obtained by integrating this video signal for each line contains flicker frequency components having different phases, and the configuration of the specific frequency detection unit 5c is complicated. become.

However, in the flicker detection mode, the charge accumulation timings of all PDs on the same line are the same, and therefore the charge accumulation timings of all columns are the same. The frequency components have the same phase. As a result, the image signal added for each line in the flicker detection mode simply includes N flicker frequency components of FIG. 4 (for the number of columns).
The added flicker frequency component will be included.
Therefore, the video signal added for each line in the flicker detection mode contains a flicker frequency component having a large single-phase level, so that the configuration of the specific frequency detecting means 5c can be simplified and the flicker frequency can be reduced. The components can be easily detected.

FIG. 5 is a diagram for explaining the charge accumulation time of the area sensor 1 when flicker occurs. In FIG. 5, f (t) is a time function of illuminance. Area sensor 1
In, the charge accumulation time of all pixels is the same, but the charge accumulation timing differs for each pixel. Therefore, a pixel having a charge storage time between a and b in FIG.
The amount of light irradiated during the charge accumulation time differs between pixels having a charge accumulation time between d. As a result, the amount of charge stored differs, causing flicker. That is, when flicker occurs, the following equation (1) is obtained. In equation (1), f (t) is a time function of illuminance (see FIG. 5).

(Equation 1) In order to prevent flicker, the charge accumulation time (the time between a and b and the time between cd in FIG. 5) is determined by the following equation (2).
It is necessary to satisfy

(Equation 2) The value of the charge accumulation time that satisfies the expression (2) is a multiple (including the flicker cycle) of the flicker cycle (the cycle of the flicker frequency component) of the illumination AC lighting cycle (including the AC lighting cycle). . That is, when the flicker cycle (AC lighting cycle) is 1/100 [s], the charge accumulation time without flicker is 1/100 [s],
2/100 [s], 3/100 [s],... Also, the flicker cycle (AC lighting cycle) is 1/120.
In the case of [s], the charge accumulation time in which flicker does not occur is 1/120 [s], 2/120 [s], and 3/120.
[S], ... However, the charge accumulation time in which these flickers do not occur needs to be shorter than the frame period of the video signal. For example, when the charge accumulation time is equal to the flicker cycle (AC lighting cycle), as shown in FIG. 6, the amount of light applied to each pixel becomes equal, and no flicker occurs.

When the flicker is not detected, the control means 5b switches the operation mode of the area sensor 1 to the imaging mode. When flicker is detected, the control unit 5b sets the charge accumulation time of the area sensor 1 to a multiple of a flicker cycle in which flicker does not occur, and switches the operation mode of the area sensor 1 to the imaging mode. For example, when flicker is detected by the flicker detection unit 5a that detects a flicker frequency component of 100 [Hz], the control unit 5b sets the charge accumulation time of the area sensor 1 to 1/100 [s], which is the same as the flicker cycle. And
The operation mode of the area sensor 1 is switched to the imaging mode.

In the imaging mode, the signal level detecting means 5i compares the integrated value of the video signal by the integrating means 6 with a preset reference value range, and when the integrated value is larger than the reference value range. Is overexposed,
When the integrated value is smaller than the reference value range, it is determined that the exposure is insufficient, and the comparison result is sent to the control unit 5b. The control means 5b adjusts the charge storage time of the area sensor 1 so that the integrated value falls within the reference value range (so that the level of the video signal is constant) when the exposure is excessive or insufficient, and The signal gain of the gain adjusting means 3 is adjusted.

In the imaging mode after the flicker is not detected, the charge accumulation time can be continuously adjusted. Therefore, the adjustment of the video signal level is sufficient if the charge accumulation time of the area sensor 1 is adjusted. Only when the adjustment cannot be performed by the charge accumulation time, the gain of the gain adjusting means 3 is adjusted.

However, in the imaging mode after the flicker is detected, the charge accumulation time needs to be set to a multiple of the flicker cycle, and the charge accumulation time can be adjusted only by a discrete value. For this reason, exposure control with a coarse resolution is performed, and an image when the charge accumulation time is switched becomes unnatural.

Therefore, in the image pickup mode after the flicker is detected, the control means 5b operates as shown in FIGS.
As described above, the charge accumulation time T of the area sensor 1 and the signal gain G of the gain control means 3 are controlled. FIG. 7 shows an illumination having a flicker frequency component of 100 [Hz] (commercial frequency of 50 Hz).
8A and 8B are diagrams illustrating control of a charge accumulation time T and a signal gain G under illumination ([Hz] illumination). FIG.
(B) is a set value of the signal gain G of the gain adjusting means 3 with respect to the subject illuminance L. FIG. 8 shows an illumination in which the flicker frequency component is 120 [Hz] (commercial frequency 60 [H]).
FIGS. 7A and 7B are diagrams illustrating control of a charge accumulation time T and a signal gain G under illumination of [z], wherein FIG. 9A illustrates a set value of the charge accumulation time T of the area sensor 1 with respect to the subject illuminance L, and FIG. This is a set value of the signal gain G of the gain adjustment unit 3 with respect to the illuminance L.

In the imaging mode under illumination causing flicker, as shown in FIGS. 7A and 8A, the charge accumulation time T can be controlled only with a discontinuous value with respect to the subject illuminance L. 7B and 8 in the range of the subject illuminance L where the same value of the charge accumulation time T is set.
As shown in (b), discontinuous exposure control is compensated for by continuously changing the value of the signal gain G, and the level of the video signal is kept constant. By controlling the charge accumulation time T and the signal gain G as shown in FIGS. 7 and 8, it is possible to obtain a video signal of a constant level without discontinuity regardless of the brightness of the subject at any time.

For a list of combinations of the set values of the charge accumulation time T and the signal gain G under illumination that causes flicker, see LU.
T5h is provided in the arithmetic means 5 in advance. FIG. 9 is a structural diagram of the LUT 5h. FIG. 9A shows a configuration of the LUT 5h under illumination of a commercial frequency of 50 [Hz].
(B) LUT5 under illumination of commercial frequency 60 [Hz]
h. The control means 5b refers to the LUT 5h according to the comparison result between the integrated value of the video signal from the signal level detection means 5i (the integrated value by the integration means 6) and the reference value range, and according to the LUT 5h, the charge accumulation time T and the signal gain G Set.

For example, if the flicker detecting means 5a is 100
When detecting the flicker frequency component of [Hz], if the initial reference address of the LUT 5h is n = 4, the control unit 5b detects the flicker, and
Referring to the address n = 4 of 5h, the charge accumulation time T of the area sensor 1 is set to 1/100 [s], and the signal gain G of the gain adjusting means 3 is set to 5 (maximum value).
In this initial setting, if the integrated value of the video signal is larger than the reference value range, the control means 5b decrements the reference address n (n = 3) and sets the address n =
3, the signal gain G of the gain adjusting means 3 is changed to 4. Also in this setting, if the integrated value of the video signal is larger than the reference value range, the control unit 5b further decrements the reference address n (n = 2), refers to the address n = 2 of the LUT 5h, and adjusts the gain. Signal gain G of means 3
To 3. In the above initial setting, if the integrated value of the video signal is smaller than the reference value range, the control unit 5b increments the reference address n (n =
5) Referring to the address n = 5 of the LUT 5h, change the signal gain G of the gain adjusting means 3 to 2 (minimum value), and set the charge storage time T of the area sensor 1 to 2/100.
Change to [s]. In this way, by providing the set values of the charge accumulation time T and the signal gain G of FIGS. 7 and 8 as the LUT 5h in the arithmetic means 5 as shown in FIG. 9, exposure control and signal gain control can be easily performed. Become.

As described above, according to the first embodiment, the charge accumulation of all PDs on the same line is started simultaneously, and the charge accumulation is sequentially started line by line. By simultaneously adding and reading, the added image signal of each line is sequentially output from the area sensor 1, flicker is detected from the added video signal of each line, and when flicker is detected, the charge accumulation is performed. By setting the time to be a multiple of the flicker cycle (flicker cycle), it is possible to detect flicker occurring in the frame in the imaging area sensor in which the charge accumulation timing is different for each pixel, and remove this flicker.

The method of incrementing or decrementing the reference address of the LUT 5h according to the detection result of the video signal level by the signal level detecting means 5i is as follows.
This is an example of a video signal level control method, and the LUT 5h can be referred to by another method. In the first embodiment, in the flicker detection mode,
Although the accumulated charges of all PDs on the same line are added and read, flicker can also be detected by adding and reading accumulated charges of a predetermined plurality of PDs of PDs on the same line. It is also possible to adopt a configuration in which an analog video signal (a video signal added for each line) output from the gain adjustment unit 3 or the pre-signal processing unit 2 is input to the flicker detection unit 5a. The detecting means 5c and the comparing means 5d can be realized by analog circuits. In these cases, it is necessary to provide an A / D converter in the flicker detection means 5a.

Embodiment 2 The imaging device according to the second embodiment is the same as the imaging device according to the first embodiment, except that
Is changed. FIG. 10 is a configuration diagram of the calculating means 5 in the imaging device according to the second embodiment of the present invention.
In FIG. 10, the same components as those in FIG. 1 are denoted by the same reference numerals.

As shown in FIG. 10, the calculating means 5 according to the second embodiment comprises a flicker detecting means 5j, a control means 5b,
It has a UT 5h and signal level detecting means 5i. The flicker detecting means 5j includes the specific frequency detecting means 5c and 5k.
And comparison means 5d.

The specific frequency detecting means 5c converts the flicker frequency component (100
[Hz] or 120 [Hz], and the specific frequency detecting unit 5k detects a frequency component other than the flicker frequency component from the video signal.
The specific frequency detecting means 5k can be realized by a BPF and an integrating means, for example, like the specific frequency detecting means 5c (see FIG. 3).

The comparator 5d compares the value of the flicker frequency component (first frequency component) detected by the specific frequency detecting means 5c with the frequency component (second frequency component) which is not the flicker frequency component detected by the specific frequency detecting means 5k. Frequency component), and when the first frequency component is larger than the second frequency component by a predetermined value or more, it is assumed that flicker has been detected.

As described above, according to the second embodiment, in addition to the specific frequency detecting means 5c for detecting a flicker frequency component (first frequency component), a frequency component (second frequency component) which is not a flicker frequency component is detected. Providing a specific frequency detecting means 5k for detection, comparing the values of the respective wave number components in the comparator 5d, and detecting flicker when the first frequency component is larger than the second frequency component by a predetermined value or more. Accordingly, the flicker detecting means can be realized with a simple configuration.

Embodiment 3 The imaging device according to the third embodiment is the same as the imaging device according to the first embodiment, except that
Is changed. FIG. 11 is a configuration diagram of the calculating means 5 in the imaging device according to the third embodiment of the present invention.
In FIG. 11, the same components as those in FIG. 1 are denoted by the same reference numerals.

As shown in FIG. 11, the calculating means 5 of the third embodiment includes a flicker detecting means 5m, a control means 5b,
It has a UT 5h and signal level detecting means 5i. The flicker detecting means 5m includes the specific frequency detecting means 5c and 5n.
, Comparing means 5d and 5p, and reference value setting means 5e.

The specific frequency detecting means 5c detects a flicker frequency component of 100 [Hz] from the added video signal for each line, and the specific frequency detecting means 5n detects a frequency component of 120 [Hz] from the video signal. Is detected.

The comparing means 5d is provided with a specific frequency detecting means 5c.
The value of the flicker frequency component (first flicker frequency component) of 100 [Hz] detected by the above is compared with the reference value of the reference value setting means 5e, and when the first flicker frequency component is larger than the reference value , Commercial frequency 50 [H
It is assumed that flicker with a flicker cycle of 1/100 [s] due to illumination of z] is detected. Also, the comparison means 5p
Is 120 detected by the specific frequency detecting means 5n.
The value of the flicker frequency component (second flicker frequency component) of [Hz] is compared with the reference value of the reference value setting means 5e, and when the first flicker frequency component is larger than the reference value, the commercial frequency 60 [ [Hz], and flicker with a flicker cycle of 1/120 [s] due to illumination of [Hz] is detected.

In the third embodiment, the LUT 5h includes:
A table for a commercial frequency of 50 [Hz] in FIG. 9A and a table for a commercial frequency of 60 [Hz] in FIG. 9B are provided. The control means 5b controls the flicker cycle 1
/ 100 [s] is detected when flicker is detected.
The charge storage time of the area sensor 1 and the signal gain of the gain control means 3 are set with reference to the table for the commercial frequency 50 [Hz] of the UT 5h, and the flicker cycle is 1/100.
When the flicker of [s] is detected, LUT5h
The charge accumulation time of the area sensor 1 and the signal gain of the gain control means 3 are set with reference to the table for the commercial frequency 50 [Hz].

As described above, according to the third embodiment, 100
A specific frequency detecting means 5c for detecting a flicker frequency component of [Hz] (first flicker frequency component);
A specific frequency detecting means 5n for detecting a flicker frequency component of 0 [Hz] (a second flicker frequency component), and a comparator 5 for comparing the first flicker frequency component with a reference value
and a comparator 5p for comparing the second flicker frequency component with a reference value. When the first flicker frequency component is larger than the reference value, a flicker period of 1/100 is provided.
When the flicker of [s] is detected, and when the second flicker frequency component is larger than the reference value, the flicker of the flicker cycle 1/120 [s] is detected. Flicker generated under illumination of 50 [Hz] and commercial frequency 60 [H]
z], it is possible to detect both flickers generated under the illumination, and it is possible to determine which commercial frequency flicker is occurring.

Embodiment 4 The calculation means 5 of the first embodiment can be realized using a microcomputer or the like. The imaging device according to the fourth embodiment described below is realized by using the microcomputer in the imaging device according to the first embodiment. FIG. 12 shows Embodiment 4 of the present invention.
FIG. 2 is a configuration diagram of a calculation unit 5 in the imaging device of FIG.

As shown in FIG. 11, the operation means 5 of the microcomputer according to the fourth embodiment has a CPU 5q and a ROM 5r. The CPU 5q is a flicker detecting unit 5a of FIG.
(Excluding the reference value setting unit 5e), the control unit 5b, and the signal level detection unit 5i. In ROM5r,
The reference value set by the reference value setting means 5e and the data of the LUT 5h are recorded. The ROM 5r stores a program for a flicker detection procedure by the flicker detection unit 5a, a signal level detection procedure by the signal level detection unit 5i, and a control procedure by the control unit 5b.

As described above, according to the fourth embodiment, the arithmetic means 5 is realized by a microcomputer, so that the arithmetic means 5 can be realized with a simple configuration.

Embodiment 5 Since the area sensor 1 according to the first embodiment is configured by CMOS, the area sensor 1 includes a pre-signal processing unit 2, a gain adjustment unit 3, an A /
It is technically possible to incorporate a circuit such as the D converter 4. The imaging device according to the fifth embodiment is the same as the imaging device according to the first embodiment except that the area sensor 1 has the above-described circuit built therein. FIG. 13 is a configuration diagram of an imaging apparatus according to Embodiment 5 of the present invention. FIG. 14 is a configuration diagram of the area sensor 11 of FIG. 13 and 14
, The same components as those in FIG. 1 or FIG. 2 are denoted by the same reference numerals.

As shown in FIG. 13, the imaging apparatus according to the fifth embodiment includes an area sensor 11, an arithmetic unit 5, and an integrating unit 6.
And signal processing means 8. As shown in FIG. 14, the area sensor 11 includes a pixel array 11a, a vertical shift register 1q, a horizontal shift register 1r, a driving pulse generating unit 1t, a pre-signal processing unit 2, a gain adjusting unit 3, , A / D converter 4, register file 11h, input terminal 11i, and register value input terminal 1.
1j and an output terminal 11k. Pixel array 11a
Are the PDs (1a, 1b, 1c, PD) of the area sensor 1 in FIG.
1d, ...), amplifiers (1e, 1f, 1g, 1h, ...),
.., The pixel selection transistors (1i, 1j, 1k, 1m,...), And the column selection transistors (1n, 1p,...).

The input terminal 11i is connected to the control means 5b (see FIG. 1) of the arithmetic means 5. The control means 5b
By sending a control signal to the input terminal 11i, the operation mode of the area sensor 11 is switched to the imaging mode or the flicker detection mode, and the charge accumulation time is set.

The output terminal 11i is connected to the integrating means 6, the signal processing means calculating means 8, and the flicker detecting means 5a (see FIG. 1) of the calculating means 4. Pixel array 11
The image pickup signal output from a is subjected to noise removal in the pre-signal processing means 2, amplified in the gain adjustment means 3, converted into a digital signal in the A / D converter 4, and output from the output terminal 11i to the integration means 6, the signal processing means. It is input to the means calculating means 8 and the flicker detecting means 5a.

The register file 11h sets a signal gain value of the gain adjusting means 3 and supplies a reference voltage value to the A / D converter 4. The register setting of the register file 11h is input from the register value input terminal 11j.
It is connected to the. When it is desired to change the signal gain of the gain adjusting means 3, the calculating means 5 outputs the signal gain value to the register value input terminal 11j, and changes the signal gain value by the register file 11h.

As described above, according to the fifth embodiment, the configuration of the image pickup apparatus can be realized by using the area sensor 11 including circuits such as the pre-signal processing means 2, the gain adjustment means 3, and the A / D converter 4. It can be simplified as shown in FIG.

[0102]

As described above, according to the imaging area sensor of the present invention, it is possible to output a signal which can easily detect flicker occurring in a frame in an imaging area sensor whose charge accumulation timing differs for each photoelectric conversion element. There is an effect that can be.

Further, according to the image pickup apparatus of the present invention, it is possible to easily detect flicker occurring in a frame in an image pickup area sensor having different charge accumulation timing for each photoelectric conversion element, and to remove the flicker. is there.

Further, according to the image pickup apparatus of the present invention, there is an effect that the flicker detecting means can be realized with a simple configuration.

According to the imaging apparatus of the present invention, both flicker at a commercial frequency of 50 [Hz] and flicker at a commercial frequency of 60 [Hz] can be detected with a simple configuration. Thus, it is possible to determine which commercial frequency causes flicker.

Further, according to the imaging device of the present invention, there is an effect that the specific frequency detecting means can be realized with a simple configuration.

Further, according to the imaging device of the present invention, there is an effect that flicker can be removed and a video signal level can be smoothly adjusted.

Further, according to the imaging apparatus of the present invention, the charge accumulation time and the signal gain value that do not cause flicker are converted into LUTs, so that the first mode after the flicker is detected can be obtained. This has the effect that the control of the charge storage time and the signal gain becomes easier.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an imaging device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of the area sensor of FIG. 1;

FIG. 3 is a configuration diagram of a specific frequency detection unit of FIG. 1;

FIG. 4 is a waveform diagram of a flicker frequency component included in an image pickup signal by a certain column of PDs in the area sensor of FIG. 2;

5 is a diagram illustrating a charge accumulation time of the area sensor of FIG. 2 when flicker occurs.

FIG. 6 is a diagram illustrating a charge accumulation time of the area sensor of FIG. 2 when flicker does not occur.

FIG. 7 illustrates an illumination (a commercial frequency of 50 [H]) in which the flicker frequency component is 100 [Hz] in the imaging apparatus of FIG.
FIG. 9 is a diagram for explaining control of a charge accumulation time and a signal gain under (illumination of z]).

8 shows an illumination (a commercial frequency of 60 [H]) with a flicker frequency component of 120 [Hz] in the imaging apparatus of FIG.
FIG. 9 is a diagram for explaining control of a charge accumulation time and a signal gain under (illumination of z]).

FIG. 9 is a structural diagram of the LUT of FIG. 1;

FIG. 10 is a configuration diagram of a calculation unit in the imaging device according to the second embodiment of the present invention.

FIG. 11 is a configuration diagram of a calculation unit in the imaging device according to the third embodiment of the present invention.

FIG. 12 is a configuration diagram of a calculation unit in the imaging device according to the fourth embodiment of the present invention.

FIG. 13 is a configuration diagram of an imaging device according to a fifth embodiment of the present invention.

FIG. 14 is a configuration diagram of the area sensor of FIG. 13;

FIG. 15 is a configuration diagram of a conventional imaging device including a CCD area sensor.

FIG. 16 is a principle diagram of a CCD area sensor.

FIG. 17 is a diagram illustrating the principle of generating flicker in a CCD area sensor.

FIG. 18 is a diagram illustrating a method of suppressing flicker in a CCD area sensor.

FIG. 19 is a configuration diagram of a conventional CMOS area sensor.

20 is a diagram illustrating scanning of the area sensor of FIG.

21 is a diagram illustrating the principle of generating flicker in the area sensor of FIG.

FIG. 22 is a diagram illustrating signal levels for respective lines when flicker occurs in the area sensor of FIG. 19;

FIG. 23 is a diagram showing a screen on which flicker has occurred due to the area sensor of FIG. 19;

[Explanation of symbols]

1 area sensor, 1a, 1b, 1c, 1d photoelectric conversion element (photodiode), 1e, 1f, 1g, 1
h amplifier, 1i, 1j, 1k, 1m, 1n, 1p
Transistor, 1q vertical shift register, 1r
Horizontal shift register, 1s output terminal, 1t drive pulse generation means, 1u, 1v, 1w, 1x reset circuit, 2 pre-signal processing means, 3 gain adjustment means,
4 A / D converter, 5 arithmetic means, 5a, 5
i, 5m flicker detection means, 5b control means, 5
c, 5k, 5n specific frequency detecting means, 5d, 5p comparing means, 5e reference value setting means, 5f BPF,
5g integrating means, 5h LUT, 5q CPU,
5r ROM, 6 integrating means, 7 output terminals, 8
Signal processing means, 11 area sensor, 11a pixel array, 11h register file, 11i input terminal, 11j register value input terminal, 11k output terminal.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Kenichi Tanaka, 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Co., Ltd. (72) Inventor Shigehiro Matoba 2-3-2, Marunouchi, Chiyoda-ku, Tokyo Inside Mitsubishi Electric Corporation (72) Inventor Yoshio Fujita 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation (72) Shinya Oeda 2-2-2 Marunouchi, Chiyoda-ku, Tokyo F term (reference) in Mitsubishi Electric Corporation 4M118 AA08 AA10 AB01 BA14 CA02 DB01 DD12 FA06 5C021 PA17 PA35 PA53 PA76 PA85 YA07 5C024 CX15 CX51 CX61 GY31 GZ26 HX07 HX18 HX23 HX31 HX55

Claims (8)

[Claims] A resetting means for individually resetting the photoelectric conversion elements and starting charge accumulation; a reading means for individually reading out the charges accumulated in the photoelectric conversion elements and outputting the charges to the outside; Driving means for controlling the start timing and the readout timing of the charge storage of each photoelectric conversion element. The charge storage timing at the time of imaging differs for each photoelectric conversion element, and the charge storage time of the photoelectric conversion element is reduced. In the adjustable imaging area sensor, in the first mode, the driving unit sequentially starts charge accumulation for each photoelectric conversion element, sequentially reads out the accumulated charge, and sequentially outputs a signal from each photoelectric conversion element. In the second mode, a plurality of photoelectric conversion elements on the same line (all photoelectric conversion elements on the same line) At the same time, the charge accumulation is started sequentially for each line, and the charges accumulated in the plurality of photoelectric conversion elements are simultaneously added and read out, and the added signal of each line is read. An imaging area sensor for sequentially outputting. 2. An image pickup area sensor according to claim 1, further comprising: a flicker detection unit for detecting flicker from a video signal added for each line by the image pickup area sensor when operated in the second mode; Operating the imaging area sensor in the second mode,
Control means for setting the charge accumulation time of the imaging area sensor to a multiple of the flicker cycle (including the flicker cycle) when the flicker is detected, and operating the imaging area sensor in the first mode. An imaging device characterized in that: 3. A flicker detecting means, comprising: a frequency detecting means for detecting a flicker frequency component from a video signal in a second mode; and a comparing means for comparing a signal level of the flicker frequency component with a preset reference value. 3. The imaging apparatus according to claim 2, further comprising: means for detecting flicker when the flicker frequency component is larger than the reference value. 4. A flicker detecting means for detecting a first frequency component which is a flicker frequency component from a video signal in a second mode, and a first flicker frequency component which is not a flicker frequency component from the image signal. Second frequency detecting means for detecting the second frequency component, and comparing means for comparing the signal level of the first frequency component and the signal level of the second frequency component, wherein the first frequency component is the second frequency component. 3. The image pickup apparatus according to claim 2, wherein flicker is detected when the frequency component is larger than a predetermined frequency component by more than a predetermined value. 5. A flicker detecting means, comprising: first frequency detecting means for detecting a first flicker frequency component from a video signal in the second mode; and detecting a second flicker frequency component from the video signal. A second frequency detecting means, a first comparing means for comparing a signal level of the first flicker frequency component with a preset reference value, a signal level of the second frequency component and the reference value And a second comparing means for comparing the first flicker frequency component with the first flicker frequency component when the first flicker frequency component is larger than the reference value.
3. The image pickup apparatus according to claim 2, wherein when the second flicker-frequency component is larger than the reference value, flicker of the second frequency is detected. 6. The frequency detecting means according to claim 3, further comprising: a band-pass filter for passing only a flicker frequency component; and an integrating means for integrating an output signal of the band-pass filter. The imaging device according to any one of the above. 7. A gain adjusting means for adjusting a gain of a video signal by the imaging area sensor; an integrating means for integrating the gain-adjusted video signal; and whether an integrated value of the video signal is within a predetermined range. Signal level determining means for determining whether or not the integrated value of the video signal is within the predetermined range in the imaging operation in the first mode when flicker is detected. 3. The imaging apparatus according to claim 2, wherein the charge accumulation time and the signal gain of the gain adjusting means are controlled. 8. A look-up table that lists combinations of charge accumulation times and signal gains that can be set in an imaging operation in the first mode when flicker is detected, wherein the control unit includes: 8. The imaging apparatus according to claim 7, wherein in the imaging operation in the first mode when is detected, the charge accumulation time and the signal gain are controlled with reference to the look-up table.