System and methods for power conservation for AMOLED pixel drivers

• US 9,262,965 B2
• Filed: 10/21/2013
• Issued: 02/16/2016
• Est. Priority Date: 12/06/2009
• Status: Active Grant

• Current Assignee: IGNIS Innovation Incorporated
• Original Assignee: IGNIS Innovation Incorporated
• Inventors: Chaji, Gholamreza, Soni, Jaimal
• Primary Examiner(s): Sharifi-Tafreshi, Koosha
• Assistant Examiner(s): Lin, Chun-Nan
• Application Number:
  US14/058,623
• Publication Number:
  US 20140043316A1
• Time in Patent Office: 848 Days
• Field of Search: 345/76, 345/204, 345/690
• US Class Current: 1/1
• CPC Class Codes: G09G 2310/0254 Control of polarity reversal in general, other than for liquid crystal displays
• CPC Class Codes: G09G 2310/066 Waveforms comprising a gently increasing or decreasing portion, e.g. ramp
• 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 2320/0673 for control of gamma adjustment, e.g. selecting another gamma curve
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 3/3258 with pixel circuitry controlling the voltage across the light-emitting element
• CPC Class Codes: G09G 3/3291 in which the data driver supplies a variable data voltage for setting the current through, or the voltage across, the light-emitting elements

Abstract

A system is provided for conserving energy in an AMOLED display having pixels that include a drive transistor and an organic light emitting device, and an adjustable source of a supply voltage for the drive transistor. The system monitors the content of a selected segment of the display, sets the supply voltage to the minimum supply voltage required for the current content of the selected segment of the display, determines whether the number of pixels requiring a supply voltage larger than the set value is greater than a predetermined threshold number, and, when the answer is negative, reduces the supply voltage by a predetermined step amount.

Claims

1. A method of conserving energy in an AMOLED display having pixels that include a drive transistor and an organic light emitting device, and an adjustable source of a supply voltage for the drive transistor, the method comprising

monitoring the content of a selected segment of the display,

setting the supply voltage to the minimum supply voltage required for the current content of said selected segment of the display, and

determining whether the number of pixels in said selected segment that require a supply voltage larger than the set value, is greater than a predetermined threshold number and, when the answer is negative, reducing the supply voltage by a predetermined step amount.

2. The method of claim 1 in which said monitoring of said content of said selected segment of the display comprises monitoring the voltage supplied to the gate input of said drive transistor input.

3. An active matrix organic light emitting device display, comprising:

an adjustable supply voltage source;

a plurality of pixels, each coupled to the adjustable supply voltage source, each pixel including;

an organic light emitting device;

a drive transistor having a source and a drain, one of which is coupled to the organic light emitting device and the other of which is coupled to the adjustable supply voltage source;

a plurality of programming voltage inputs coupled to the gates of the drive transistors of the plurality of pixels, the programming voltage inputs providing a programming voltage indicative of a desired brightness of each of the plurality of pixels; and

a supply voltage controller coupled to the adjustable voltage source to regulate the level of a supply voltage supplied to each of the drive transistors, the supply voltage controller

monitoring the content of a selected segment of the display,

setting the supply voltage to the minimum supply voltage required for the current content of said selected segment of the display, and

reducing the supply voltage by a predetermined step amount when the number of pixels in the selected segment that require a supply voltage larger than the set value, is greater than a predetermined threshold number.

4. The active matrix organic light emitting device display of claim 3 in which said content of said selected segment of the display is monitored by monitoring the voltage supplied to the gate input of said drive transistor input.