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Patent Issued for Solid-State Imaging Device, Drive Method Therefor, and Electronic Device

February 26, 2014



By a News Reporter-Staff News Editor at Electronics Newsweekly -- From Alexandria, Virginia, VerticalNews journalists report that a patent by the inventor Okuno, Jun (Kanagawa, JP), filed on July 15, 2010, was published online on February 11, 2014.

The patent's assignee for patent number 8648939 is Sony Corporation (Tokyo, JP).

News editors obtained the following quote from the background information supplied by the inventors: "The present invention relates to a solid-state imaging device, a drive method therefor, and an electronic device equipped with the solid-state imaging device.

"Solid-state imaging devices are roughly classified into two types of solid-state imaging devices typified by a CCD (Charge Coupled Device) image sensor and a CMOS (Complementary Metal Oxide Semiconductor) image sensor. Those solid-state imaging devices are widely used in digital still cameras, digital video cameras, and so forth. Recently, from the viewpoints of a lower supply voltage and lower power consumption, MOS type image sensors are used more as solid-state imaging devices to be installed in mobile devices, such as camera-equipped cellular phones.

"As a CMOS solid-state imaging device which achieves simultaneous storage in the individual pixels, a CMOS solid-state imaging device has been proposed which has a memory element (capacitor) provided for each pixel to ensure global shutter imaging. Since a CCD solid-state imaging device has a vertical transfer register and simultaneously into reads electric charges in all the pixels therein, the global shutter imaging can be implemented.

"In the CCD solid-state imaging device having a vertical transfer register to ensure global shutter imaging, light leaks into the vertical transfer register, causing a smear. The CCD solid-state imaging device can detect a smear at an optical black pixel region (so-called optical black (OPB) region) for each column. Accordingly, the CCD solid-state imaging device can correct a smear by performing a process of subtracting a signal (OPB data) obtained from the optical black pixel region on from a signal acquired from a pixel (see, for example, JP-A-2006-210560 (Patent Document 1))."

As a supplement to the background information on this patent, VerticalNews correspondents also obtained the inventor's summary information for this patent: "The CMOS solid-state imaging device which has a memory element provided for each pixel to ensure global shutter imaging needs to cope with occurrence of a smear originated from light leaking into the memory element holding an electric charge and degradation of the image quality caused by the smear. Since a signal (smear) originated from light leaked into each pixel is not transferred to an optical black pixel region in the CMOS solid-state imaging device, leak light for each pixel cannot be detected. As a result, the CMOS solid-state imaging device capable of implement global shutter imaging has a problem that the degraded image quality originated from the leak light cannot be corrected.

"Thus, it is desirable to provide a solid-state imaging device which can correct a signal originated from leak light leaked into a memory part in a CMOS solid-state imaging device which can implement global shutter imaging, and a drive method for the solid-state imaging device.

"It is also desirable to provide an electronic device, such as a camera, equipped with such a solid-state imaging device.

"A solid-state imaging device according to an embodiment of the present invention has a normal pixel and a leak-light correcting pixel disposed in a pixel section capable of performing a global shutter. The normal pixel includes at least a photoelectric conversion part and a memory part adjacent to the photoelectric conversion part. The leak-light correcting pixel corrects degradation of an image quality originated from leak light leaked into the memory part.

"In the solid-state imaging device according to the embodiment of the invention, an electric charge corresponding to a combined signal of a normal pixel and a leak signal is stored in the memory part of the normal pixel, and the combined signal is output from the normal pixel. The leak-light correcting pixel outputs only a leak signal. Thereafter, the combined signal and the leak signal are subjected to a subtraction process to acquire a normal signal.

"A drive method for a solid-state imaging device according to another embodiment of the invention uses a solid-state imaging device which has a normal pixel and a leak-light correcting pixel disposed in a pixel section having a plurality of pixels and capable of performing a global shutter. The normal pixel includes at least a photoelectric conversion part and a memory part adjacent to the photoelectric conversion part. The leak-light correcting pixel has at least a light receiving region and a memory part adjacent to the light receiving region.

"According to the embodiments of the invention, a combined signal of a normal signal and a leak signal originated from leak light leaked into the memory part are output from the normal pixel, and only the leak signal originated from leak light leaked into the memory part is output from the leak-light correcting pixel. A subtraction process is performed on the combined signal from the normal pixel and the leak signal from the leak-light correcting pixel to correct a leak signal from the normal pixel.

"Since the drive method for a solid-state imaging device according to the embodiment of the invention subtracts the normal signal from the normal pixel the leak signal originated from leak light into the memory part in subsequent signal processing, the leak signal in the normal pixel is corrected.

"An electronic device according to still another embodiment of the invention includes an optical system, a solid-state imaging device, and a signal processing circuit that processes an output signal of the solid-state imaging device. The solid-state imaging device has a normal pixel and a leak-light correcting pixel disposed in a pixel section capable of performing a global shutter. The normal pixel includes at least a photoelectric conversion part and a memory part adjacent to the photoelectric conversion part. The leak-light correcting pixel corrects degradation of an image quality originated from leak light leaked into the memory part. Further, the solid-state imaging device has a function of performing a subtraction process on a signal acquired from the leak-light correcting pixel and a signal acquired from the normal pixel around the leak-light correcting pixel to correct the signal acquired from the normal pixel around the leak-light correcting pixel.

"Since the electronic device according to the embodiment of the invention has the leak-light correcting pixel disposed in the pixel section of the solid-state imaging device, a leak signal can be detected. A leak signal in the normal pixel can be corrected by performing a subtraction process on the leak signal and a combined signal of the normal signal in the normal pixel and the leak signal.

"As apparent from the above, the solid-state imaging device and drive method therefor according to the embodiments of the invention can correct a signal originated from leak light leaked into the memory part in the solid-state imaging device which can implement global shutter imaging.

"Equipped with this solid-state imaging device, the electronic device according to the embodiment of the invention can correct a signal originated from leak light leaked into the memory part in the solid-state imaging device which can implement global shutter imaging, thus providing an electronic device with a high image quality and high quality."

For additional information on this patent, see: Okuno, Jun. Solid-State Imaging Device, Drive Method Therefor, and Electronic Device. U.S. Patent Number 8648939, filed July 15, 2010, and published online on February 11, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=44&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=2154&f=G&l=50&co1=AND&d=PTXT&s1=20140211.PD.&OS=ISD/20140211&RS=ISD/20140211

Keywords for this news article include: Electronics, Sony Corporation, Signal Processing.

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Source: Electronics Newsweekly


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