Read-out circuit for active matrix imaging arrays

• US 6,300,977 B1
• Filed: 12/02/1997
• Issued: 10/09/2001
• Est. Priority Date: 04/07/1995
• Status: Expired due to Fees

• Current Assignee: Hanger Solutions, LLC (IP Investments Group LLC)
• Original Assignee: iFire Technology Inc.
• Inventors: Huang, Zhong Shou, Waechter, David
• Primary Examiner(s): Garber, Wendy R.
• Assistant Examiner(s): White, Mitchell
• Application Number:
  US08/930,749
• Time in Patent Office: 1,407 Days
• Field of Search: 348/301, 348/302, 348/303, 348/304, 348/305, 348/308, 378/98.8, 250/208.1
• US Class Current: 348/300
• CPC Class Codes: H04N 25/766 comprising control or output lines used for a plurality of functions, e.g. for pixel output, driving, reset or power

Abstract

Improved circuitry for active matrix image arrays which, in one application reduces the number of source or gate lines for a given number of pixels, and in another application extends the dynamic range of the imaging array without reducing the number of source or gate lines. Each circuit includes multiple electrodes per pixel and multiple thin film transistors for switching charge from the pixel electrodes to the data line.

Claims

1. A method of operating an imaging array including a plurality of pixels arranged in rows and columns, each of said pixels being bounded by at least one data line and at least two control lines connected to a scanning control circuit, and each of said pixels including at least two pixel electrodes and at least two switching means, a first one of said pixel electrodes being connected to said at least one data line via a first one of said switching means, said first one of said switching means having a control input thereof connected to a first one of said control lines for receiving a first scanning pulse from said scanning control circuit for transferring charge on said first one of said pixel electrodes to said at least one data line, a second one of said pixel electrodes being connected to said first one of said pixel electrodes via a second one of said switching means, said second one of said switching means having a control input thereof connected to a second one of said control lines for receiving a second scanning pulse from said control circuit for transferring charge on said second one of said pixel electrodes to said first one of said pixel electrodes after said charge on said first one of said pixel electrodes has been transferred to said at least one data line, the method comprising the steps of:

a) scanning successive ones of said control lines such that for each of said pixels charge carried by said first one of said pixel electrodes is transferred to said at least one data line in response to scanning said first one of said at least two control lines, and a portion of charge carried by said second one of said pixel electrodes is transferred to said first one of said pixel electrodes in response to scanning said second one of said control lines;

b) scanning successive ones of said control lines a second time such that said portion of charge transferred from said second one of said pixel electrodes to said first one of said pixel electrodes is transferred to said at least one data line; and

c) multiplying said portion of charge transferred to said at least one data line by a correction factor proportional to capacitance ratio between said first and second pixel electrodes, whereby each of said pixels functions as a pixel pair defined by said first and second pixel electrodes.

2. The method of claim 1, further comprising the steps of repeatedly further scanning successive ones of said control lines for clearing charge from said second one of said pixel electrodes.

3. The method of claim 1, further comprising the step of simultaneously scanning all of said control lines for clearing charge from said second one of said pixel electrodes.

4. In an imaging array comprising a plurality of pixels arranged in rows and columns, each of said pixels being bounded by at least one data line and at least two control lines connected to a scanning control circuit, the improvement wherein each of said pixels comprises at least two pixel electrodes and at least two switching means, a first one of said pixel electrodes being connected to said at least one data line via a first one of said switching means, said first one of said switching means having a control input thereof connected to a first one of said control lines for receiving a first scanning pulse from said scanning control circuit for transferring charge on said first one of said pixel electrodes to said at least one data line, a second one of said pixel electrodes being connected to said first one of said pixel electrodes via a second one of said switching means, said second one of said switching means having a control input thereof connected to a second one of said control lines for receiving a second scanning pulse from said control circuit for transferring charge on said second one of said pixel electrodes to said first one of said pixel electrodes after said charge on said first one of said pixel electrodes has been transferred to said at least one data line;

and wherein each of said switching means further comprises a thin-film-transistor (TFT), and each said thin-film-transistor (TFT) is a dual gate device.

5. The improvement of claim 4, wherein a source terminal of said first switching means is connected to said at least one data line, a gate terminal of said first switching means is connected to said first one of said control lines, and a drain terminal of said first switching means is connected to said first one of said pixel electrodes.

6. The improvement of claim 4, wherein a source terminal of said second switching means is connected to said first one of said pixel electrodes, a gate terminal of said second switching means is connected to said second one of said control lines, and a drain terminal of said second switching means is connected to said second one of said pixel electrodes.

7. A method of operating an imaging array including a plurality of pixels arranged in rows and columns, each of said pixels being bounded by at least one data line and at least two control lines connected to a scanning control circuit, and each of said pixels including at least two pixel electrodes and at least two switching means, a first one of said pixel electrodes being connected to said at least one data line via a first one of said switching means, said first one of said switching means having a control input thereof connected to a first one of said control lines for receiving a first scanning pulse from said scanning control circuit for transferring charge on said first one of said pixel electrodes to said at least one data line, a second one of said pixel electrodes being connected to said first one of said pixel electrodes via a second one of said switching means, said second one of said switching means having a control input thereof connected to a second one of said control lines for receiving a second scanning pulse from said control circuit for transferring charge on said second one of said pixel electrodes to said first one of said pixel electrodes after said charge on said first one of said pixel electrodes has been transferred to said at least one data line, the method comprising the steps of:

a) scanning successive ones of said control lines such that for each of said pixels charge carried by said first one of said pixel electrodes is transferred to said at least one data line in response to scanning said first one of said at least two control lines, and charge carried by said second one of said pixel electrodes is redistributed to both said first one of said pixel electrodes and said second one of said pixel electrodes in response to scanning said second one of said control lines; and

b) scanning successive adjacent pairs of said control lines a second time such that all remaining charge on said first and second ones of said pixel electrodes is transferred to said at least one data line.