System and methods for extraction of parasitic parameters in AMOLED displays

• US 9,171,500 B2
• Filed: 11/11/2013
• Issued: 10/27/2015
• Est. Priority Date: 05/20/2011
• Status: Active Grant

• Current Assignee: IGNIS Innovation Incorporated
• Original Assignee: IGNIS Innovation Incorporated
• Inventors: Chaji, Gholamreza, Azizi, Yaser
• Primary Examiner(s): LEE, NICHOLAS J
• Application Number:
  US14/076,336
• Publication Number:
  US 20140062993A1
• Time in Patent Office: 715 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G09G 2230/00 Details of flat display driving waveforms
• CPC Class Codes: G09G 2300/0426 Layout of electrodes and connections
• CPC Class Codes: G09G 2300/0819 used for counteracting undesired variations, e.g. feedback or autozeroing
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2300/0861 with additional control of the display period without amending the charge stored in a pixel memory, e.g. by means of additional select electrodes
• CPC Class Codes: G09G 2310/0248 Precharge or discharge of column electrodes before or after applying exact column voltages
• CPC Class Codes: G09G 2310/0289 Details of voltage level shifters arranged for use in a driving circuit
• CPC Class Codes: G09G 2310/0291 Details of output amplifiers or buffers arranged for use in a driving circuit
• CPC Class Codes: G09G 2310/061 for resetting or blanking
• CPC Class Codes: G09G 2320/029 by monitoring one or more pixels in the display panel, e.g. by monitoring a fixed reference pixel
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 3/3225 using an active matrix
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element

Abstract

A system reads a desired circuit parameter from a pixel circuit that includes a light emitting device, a drive device to provide a programmable drive current to the light emitting device, a programming input, and a storage device to store a programming signal. One embodiment of the extraction system extracts a parasitic capacitance value from a pixel circuit by measuring at least one parameter of the pixel circuit when in a first state having a first set of operating voltages and currents, measuring at least one parameter of the pixel circuit when in a second state having a second set of operating voltages and currents different from the first set, and extracting the value of a selected parasitic capacitance from the measurements.

Claims

1. A method of extracting a parasitic capacitance value from a pixel circuit including a light emitting device, a drive device to provide a programmable drive current to the light emitting device, a programming input, and a storage device to store a programming signal, the method comprising:

measuring at least one parameter of the pixel circuit when in a first state having a first set of operating voltages and currents,

measuring at least one parameter of the pixel circuit when in a second state having a second set of operating voltages and currents different from said first set,

modeling the effect of parasitic capacitance on measured parameters at different sets of operating conditions, said modeling being done before or after said measuring of said parameters of the pixel circuit when in said first and second states, and

extracting the value of a selected parasitic capacitance from said measurements and said modeling.

2. The method of claim 1 in which said measured parameter is a current in said pixel circuit.

3. The method of claim 1 in which said measured parameter is a charge in said pixel circuit.

4. A method of extracting a parasitic capacitance value from a pixel circuit including a light emitting device, a drive device to provide a programmable drive current to the light emitting device, a programming input, and a storage device to store a programming signal, the method comprising:

measuring at least one parameter of the pixel circuit when in a first state having a first set of operating voltages and currents,

measuring at least one parameter of the pixel circuit when in a second state having a second set of operating voltages and currents different from said first set,

determining the difference between the two measurements, and

measuring at least one parameter of the pixel circuit when in a third state having a known set of operating voltages and currents, and modifying this measurement by a gain based on said determined difference.

5. The method of claim 4 in which said pixel circuit is part of a display having a prescribed specification, and said gain is adjusted to make said pixel circuit match said prescribed specification.