Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
  • H04N25/60—Noise processing, e.g. detecting, correcting, reducing or removing noise
  • H04N25/68—Noise processing, e.g. detecting, correcting, reducing or removing noise applied to defects
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
  • H04N23/80—Camera processing pipelines; Components thereof
  • H04N23/84—Camera processing pipelines; Components thereof for processing colour signals
  • H04N23/843—Demosaicing, e.g. interpolating colour pixel values
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
  • H04N25/70—SSIS architectures; Circuits associated therewith
  • H04N25/702—SSIS architectures characterised by non-identical, non-equidistant or non-planar pixel layout
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F39/00—Integrated devices, or assemblies of multiple devices, comprising at least one element covered by group H10F30/00, e.g. radiation detectors comprising photodiode arrays
  • H10F39/80—Constructional details of image sensors
  • H10F39/802—Geometry or disposition of elements in pixels, e.g. address-lines or gate electrodes
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
  • H04N25/10—Circuitry of solid-state image sensors [SSIS]; Control thereof for transforming different wavelengths into image signals
  • H04N25/11—Arrangement of colour filter arrays [CFA]; Filter mosaics
  • H04N25/13—Arrangement of colour filter arrays [CFA]; Filter mosaics characterised by the spectral characteristics of the filter elements
  • H04N25/134—Arrangement of colour filter arrays [CFA]; Filter mosaics characterised by the spectral characteristics of the filter elements based on three different wavelength filter elements

Definitions

• the invention relates generally to the field of image sensors having an array of active imaging pixels, and in particular to interspersing substitutional pixels that are substantially different in design from the imaging pixels in the array of pixels for providing information or functions and the like for improving performance.
• image sensors are manufactured within a certain tolerance specification in which a few pixels have somewhat undesirable characteristics. These pixels are commonly referred to as “defective pixels” because, although they are operational, they do not have the same desired performance characteristics as the other pixels. Given a sufficiently low density, these defective pixels do not substantially degrade the quality of a captured image because they are typically replaced by calculated substitute values, which closely approximate the value if the pixel was not defective.
• One such technique is to replace the defective pixel value with the average of a predetermined number of nearest neighbor values. This predetermined number of nearest neighbor could be two immediate adjacent pixels or four immediate adjacent pixels.
• image sensors are also formed from an array of identical cells (typically four immediate adjacent pixels) so that the imaging characteristics of the sensor are substantially uniform across the array. Design of these cells are often a trade-off or compromise of several competing imaging performance parameters, such as read-out rate, photosensitivity, and photo-response non-uniformity. Consequently, a technique or method is needed to provide improvements in a specific imaging performance parameter without substantial degradation of other aspects. One such improvement is to use the knowledge that defective pixels do not substantially degrade image quality for enhancing other imaging parameters.
• the present invention is directed to overcoming one or more of the problems set forth above.
• the invention resides in an image sensor including (a) a plurality of photosensitive sites which convert incident light into a charge for forming a bounded array of active imaging pixels; (b) one or more substitutional pixel sites arranged in predetermined locations and interspersed amongst the boundary of the array of active imaging pixels; wherein the substitutional pixels are of a different design from the active imaging pixels which provides data, information or function different from the active pixels for improving performance, operation, manufacture, and/or assembly of the image sensor.
• Fig. 1 is a top view of the image sensor of the present invention
• Fig. 2 is a camera for implementing a preferred commercial embodiment for the image sensor of Fig. 1
• Fig. 3 is an illustration of a technique for computing an average of nearest neighbors that may be used as a pixel value for the substitutional pixels.
• image sensors may be formed using a CCD (charge coupled device) technology or using a CMOS (complementary metal oxide semiconductor) technology.
• Image sensors made with CMOS technology use an "active element” such as a transistor in each pixel. This is typically referred to as an “active CMOS” image sensor.
• active CMOS imagers one or more active elements in the pixel converts the signal charge into a voltage, thereby providing a voltage which is representative of the light intensity upon that pixel.
• a plurality of pixels 20 is arranged in an array of N by M pixels for forming a bounded active imaging array or area, where N and M are any predetermined number of pixels such as, for example, 200 to 4,000.
• Each pixel 20 captures incident light that is converted into a charge representative of the intensity of the incident light. For clarity, it is noted that these pixels collectively form the active imaging pixels.
• the active imaging pixels 20 are energized for operation via a plurality of supply buses 30 that are energized to a predetermined voltage level as is well known in the art.
• a predetermined number of the active imaging pixels 20 are replaced by pixels 40 that are used for an entirely or substantially different purpose than the active imaging pixels.
• These pixels 40 are referred to hereinafter as substitutional pixels. These substitutional pixels 40 are used to provide data, information and/or function different from the active pixels 20 for improving performance, operation, manufacture, and/or assembly of the image sensor 10.
• the substitutional pixels 40 may be used as amplifier circuits or buffer circuits for improving distribution of current or voltage across the array of active imaging pixels.
• amplifier circuits and buffer circuits are well known in the art and are not described in detail herein.
• amplifier circuits or buffer circuits may also be used for improving signal integrity within or across the array of pixels.
• the voltage provided by the active elements in the pixel must be supplied over a long metal output line that has some resistance and capacitance.
• the resistance and capacitance of the metal line may increase the time required to establish that voltage along the entire line.
• a buffer amplifier may be used in a substitutional pixel to decrease the time required to establish the voltage along the entire line.
• these substitutional pixels may be used for determining alternate image parameters including alternate color, infrared constituents or other photo-metric parameters. For example, a filter that allows only infrared light through to the photosensitive region of the pixel may be placed over a pixel so that a sampling of the infrared component of the incident radiation may be obtained.
• substitutional pixel sites may be used to provide a ground contact within the image sensor to maintain a more uniform ground potential in the well.
• substitutional pixels may also be used as fiducial elements, which can be used for a mechanism for aligning the image sensor.
• substitutional pixels may provide dark reference levels for image processing. Dark reference signals are taken with the pixel covered in some manner so that it is not exposed to light. The value from this "dark" exposure is then used for calibration during image processing.
• This dark reference signal from the substitutional pixels can be in lieu of or in additional to the usual dark reference pixel values.
• a digital camera 50 for implementing the image sensor 10 of the present invention in a typical commercial embodiment to which an ordinary consumer is accustomed.
• the camera 50 also includes a mechanism, preferably an algorithm, for correcting the image created by the plurality of active imaging pixels by providing a signal level for an image site at a substitutional pixel location.
• the processor 60 of the camera 50 may compute this correction value by well-known programming techniques. This algorithm, for example, could be by computing the average of a predetermined number of nearest neighbors. Referring to Fig.
• the nearest neighbors could be the two immediately adjacent nearest neighbors (A and B) of the pixel of interest (X) or the four immediately adjacent nearest neighbors (C, D, E and F) of the pixel of interest (Y).
• color filters are typically arranged on top of the active pixels in an alternating RGBG pattern, known as the Bayer pattern, where R indicates a red filter, B a blue filter, and G a green filter, as shown in Fig. 4a.
• the correction value could use the closest neighboring color pixels.
• the nearest neighbors could be A and B for a green pixel of interest X or neighbors C, D, E, F for green pixel of interest Y.

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• Engineering & Computer Science (AREA)
• Multimedia (AREA)
• Signal Processing (AREA)
• Physics & Mathematics (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Solid State Image Pick-Up Elements (AREA)
• Transforming Light Signals Into Electric Signals (AREA)

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• 2003
  • 2003-10-22 US US10/691,047 patent/US7304673B2/en not_active Expired - Lifetime
• 2004
  • 2004-10-19 WO PCT/US2004/034324 patent/WO2005043894A1/en not_active Ceased
  • 2004-10-19 DE DE602004026462T patent/DE602004026462D1/de not_active Expired - Lifetime
  • 2004-10-19 KR KR1020067007623A patent/KR101103956B1/ko not_active Expired - Lifetime
  • 2004-10-19 EP EP04795482A patent/EP1676435B1/en not_active Expired - Lifetime
  • 2004-10-19 JP JP2006536687A patent/JP2007509580A/ja active Pending
  • 2004-10-19 CN CNB2004800310549A patent/CN100550994C/zh not_active Expired - Lifetime

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