Pixel array, imaging sensor including the pixel array and digital camera including the imaging sensor

• US 7,821,553 B2
• Filed: 12/30/2005
• Issued: 10/26/2010
• Est. Priority Date: 12/30/2005
• Status: Active Grant

• Current Assignee: Globalfoundries US Incorporated (GlobalFoundries, Inc.)
• Original Assignee: International Business Machines Corporation
• Inventors: Loiseau, Alain, Rassel, Richard J., Ellis-Monaghan, John J., Jaffe, Mark D.
• Primary Examiner(s): Whipkey; Jason
• Assistant Examiner(s): HOGUE, DENNIS A
• Application Number:
  US11/275,417
• Publication Number:
  US 20070153104A1
• Time in Patent Office: 1,761 Days
• Field of Search: 348/234, 348/273, 348/276, 348/277, 348/279, 348/280, 348/308, 348/275, 345/589
• US Class Current: 348/277
• CPC Class Codes: H04N 25/133 including elements passing panchromatic light, e.g. filters passing white light
• CPC Class Codes: H04N 25/135 based on four or more different wavelength filter elements

Abstract

A pixel array in an image sensor, the image sensor and a digital camera including the image sensor. The image sensor includes a pixel array with colored pixels and unfiltered (color filter-free) pixels. Each unfiltered pixel occupies one or more array locations. The colored pixels may be arranged in uninterrupted rows and columns with unfiltered pixels disposed between the uninterrupted rows and columns. The image sensor may in CMOS with the unfiltered pixels reducing low-light noise and improving low-light sensitivity.

Claims

1. An imaging sensor structure comprising:

a plurality of pixels arranged in at least one row, wherein said plurality of pixels is an array of pixels; and

a first type pixel located adjacent to a second type pixel in said at least one row, wherein said first type pixel includes a color filter, said second type pixel is a color filter-free light efficient cell (LEC) collecting three times the per unit area energy of the first type pixel, LECs having at least twice the light sensing area of the first type pixels, each LEC not sharing a common boundary with any other LEC and sensing all light to the respective light sensing area independently of light sensed by each other LEC, wherein said surface area of said second type pixel is L-shaped occupying two rows in one column and two columns in one row and being greater than said surface area of said first type pixel, and wherein said imaging sensor is a CMOS imaging sensor comprises diagonals of green pixels interleaved with diagonals of alternating blue pixels and red pixels, said diagonals being periodically interrupted by said plurality of L-shaped LECs.

2. A CMOS imaging sensor comprising:

a two dimensional pixel array of photodiodes;

a plurality of pixels in said pixel array being color pixels, each of said color pixels being sensitive to light within a selected color frequency band, wherein said pixel array comprises diagonals of green pixels and diagonals of blue pixels and red pixels; and

remaining pixels in said pixel array being occupied by light efficient cells (LECs), said LECs being non-contiguous and sensitive to light in a frequency range including each said selected color frequency band, and collecting three times the per array location energy of the first type pixel and having at least twice the light sensing area of the first type pixels, each LEC sensing all light to the respective light sensing area independent from each other LEC, wherein said LECs are L-shaped occupying two rows in one column and two columns in one row, and wherein pixels in said pixel array are arranged in diagonals of green pixels interleaved with diagonals of alternating blue pixels and red pixels, said diagonals of green pixels being periodically interrupted by said plurality of L-shaped LECs.

3. A CMOS imaging sensor as in claim 2, wherein said color pixels include red, green and blue pixels, each color pixel occupying a single array location.

4. A digital camera including a CMOS imaging sensor, said CMOS imaging sensor comprising:

a two dimensional pixel array of photodiodes;

a plurality of pixels in said pixel array occupying single array locations and being color pixels;

a first plurality of said color pixels being red pixels;

a second plurality of said color pixels being green pixels;

remaining ones of said color pixels being blue pixels; and

remaining pixels in said pixel array being occupied by light efficient cells (LECs) having at least twice the light sensing area of said color pixels, said LECs being non-contiguous and sensitive to light in a frequency range including the red, green and blue visible frequency band, each LEC sensing all light to the respective light sensing area independent from each other LEC, wherein said LECs are L-shaped occupying two rows in one column and two columns in one row, wherein pixels in said pixel array are arranged in diagonals of green pixels interleaved with diagonals of alternating blue pixels and red pixels, said diagonals being periodically interrupted by said plurality of L-shaped LECs.

5. A digital camera including an imaging sensor, said imaging sensor comprising:

a pixel array of a plurality of color filtered pixels arranged a plurality of rows and columns, wherein said plurality of color filtered pixels comprises a plurality of red, green and blue color filtered pixels, each occupying one array location; and

a plurality of light efficient cells (LECs) non-contiguous and distributed throughout said pixel array, each of said plurality of LECs occupying at least two array locations, each LEC collecting three times the per array location energy of the first type pixel and having at least twice the light sensing area of the first type pixels, each LEC sensing all light to the respective light sensing area independent from each other LEC, wherein said imaging sensor is a CMOS imaging sensor comprising diagonals of green pixels interleaved with diagonals of alternating blue pixels and red pixels, said diagonals being periodically interrupted by said plurality of LECs, each of said LECs being L-shaped and occupying two rows in one column and two columns in one row.