High dynamic range segmented pixel sensor array

• US 5,789,737 A
• Filed: 01/22/1997
• Issued: 08/04/1998
• Est. Priority Date: 01/22/1997
• Status: Expired due to Term

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Street, Robert A.
• Primary Examiner(s): Westin, Edward P.
• Assistant Examiner(s): PYO, KEVIN K
• Application Number:
  US08/787,461
• Time in Patent Office: 559 Days
• Field of Search: 250/208.1, 250/214.1, 257/290, 257/291, 257/292, 257/440, 257/443, 257/444
• US Class Current: 250/208.1
• CPC Class Codes: H01L 27/14643 Photodiode arrays; MOS imagers

Abstract

A photodiode sensor for use as a pixel element of a sensor array includes the sensor area segmented into a plurality of discrete portions. Each discrete portion has a distinctive responsiveness to incident illumination, either with regard to capacitance or sensitivity. The portions are in common communication with a data line for generating a sum charged output representative of the illumination on the cumulative sensor portions. Since the dynamic range of the cumulative discrete portions is greater than any single one sensor portion, a wider dynamic range for sensor operability is achieved.

Claims

1. An image sensor array comprised of a plurality of high dynamic range sensors disposed as matrix addressable pixel elements each associated with a gate line, a data line and a bias voltage line,

wherein each of the pixel elements comprises an amorphous silicon sensor segregated into a plurality of discrete sensor portions, each portion having a distinctive responsiveness to incident illumination, wherein the portions are in common communication with the data line for generating a summed charge output representative of the illumination;

and,

read-out electronics for selectively addressing the data line and generating an electrical signal representative of the illumination.

2. The sensor array as defined in claim 1 wherein the distinctive responsiveness of each sensor portion comprises different sensitivities.

3. The sensor array as defined in claim 2 wherein the discrete sensor portions have differently sized active areas causing the different sensitivities.

4. The sensor array as defined in claim 3 wherein the sensor portions have different charge saturations.

5. The sensor array as defined in claim 1 wherein each sensor portion bus has approximately a same capacitance.

6. The sensor array as defined in claim 5 wherein the capacitance results from a capacitor formed by a gate metal pad connected to a common voltage or ground.

7. The sensor array as defined in claim 1 wherein the sensor comprises an amorphous silicon photodiode.

8. The sensor array as defined in claim 1 wherein the sensor portions have terminal ends in parallel connection to a switch pad of a switch wherein the switch includes means for simultaneous discharge of the sensor portions for the summed charge output by control of the read-out electronics.

9. A pixel element for use in a sensor array comprising an hydrogenated amorphous silicon sensor for integrating an accumulated charge representative of energy incident to the sensor, including:

a plurality of discrete sensor regions comprising the sensor wherein the regions each individually consume a different percentage of available fill for a cumulative wide dynamic range, the sensor regions being in parallel connection to a single discharge switch for simultaneous discharge of integrated charge; and

,

a capacitor formed between a one of the sensor regions and a metallization line of the element for increasing a capacitance of the one region beyond an inherent region capacitance.

10. The pixel element as claimed in claim 9 wherein the sensor consists of three of said discrete sensor regions, said three comprising approximately 50%, 25% and 10% of the fill factor, respectively.