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From the background information supplied by the inventors, news correspondents obtained the following quote: "The present invention relates to solid-state imaging devices and driving methods therefor, and in particular, to a complementary metal-oxide semiconductor (CMOS) or metal-oxide semiconductor (MOS) solid-state imaging device and a driving method therefor.
"CMOS solid-state imaging devices (hereinafter referred to as 'CMOS image sensors'), which can be produced in a process similar to that for CMOS integrated circuits, are known as solid-state imaging devices (see, for example, Japanese Patent Specification No. 3000782). Regarding the CMOS image sensors, by using miniaturization technology related to a CMOS process, an active structure having an amplifying function for each pixel can be easily produced. In addition, the CMOS image sensors have a feature in that peripheral circuits, such as driving circuits for driving a pixel array and a signal processing circuit for processing signals output from the pixel array, are integrated on the same chip (substrate) for the pixel array. Accordingly, in recent years, the CMOS image sensors have attracted attention, and many researches and developments concerning the CMOS image sensors have been performed."
Supplementing the background information on this patent, VerticalNews reporters also obtained the inventors' summary information for this patent: "Analysis by the inventors of the present invention has indicated that, in a solid-state imaging device such as a CMOS image sensor, one of causes of image deterioration is based on the following mechanism. Specifically, when a signal is output from each pixel to a vertical signal line, the potential of the vertical signal line changes. Even if, at this time, the signal is read from the pixel in each row, the potentials of vertical signal lines in the entirety of the pixel array change. Accordingly, the potentials of wells in the pixel array are fluctuated by capacitive coupling in the entirety of the pixel array. When the potential of one well in the pixel array fluctuates while the signal is being read from the pixel, the fluctuation in potential is superimposed on the signal from the pixel. The superimposed fluctuation causes noise and shading (broad unevenness on a captured image on the screen).
"The present invention has been made in view of the above circumstance. Accordingly, there is a need for providing a solid-state imaging device and driving method therefor that, by suppressing a fluctuation in well potential of a pixel array while a signal is being read from a pixel, prevent generation of noise and shading caused by the fluctuation in well potential.
"According to an embodiment of the present invention, there is provided a solid-state imaging device including a pixel array including pixels arranged two-dimensionally, with a signal line provided in each column of the arranged pixels, each pixel including a photoelectric conversion element, and a fixing unit for fixing the potential of the signal line, which is obtained before the pixel has an operating period, to an intermediate potential between a first power-supply potential and a second power-supply potential.
"In the above solid-state imaging device, before the pixel has the operating period, by fixing the potential of the signal line to the intermediate potential, the potential of the signal line changes from the intermediate potential to a reset level if the reset level is output from the pixel to the signal line. Thus, the potential of the signal line has a small change. This minimizes a fluctuation (change) in the potential of the signal line when the reset level is output. Therefore, a fluctuation in well potential of a pixel array due to the fluctuation in the potential of the signal line is suppressed.
"According to another embodiment of the present invention, there is provided a driving method for a solid-state imaging device including pixels two-dimensionally arranged in matrix form, with a signal line provided in each column of the arranged pixels, each pixel including a photoelectric conversion element, wherein, before the pixel has an operating period, the potential of the signal line is fixed to an intermediate potential between a first power-supply potential and a second power-supply potential.
"According to an embodiment of the present invention, by suppressing a fluctuation in well potential in a pixel array, caused by a fluctuation in potential of a signal line, it is ensured that the fluctuation in well potential is prevented from affecting a reset level and a signal level. Therefore, this prevents generation of noise and shading caused by the fluctuation in well potential."
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Keywords for this news article include: Electronics, Semiconductor,
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