Method for saving power in an organic electroluminescent display using white light emitting elements

• US 7,012,588 B2
• Filed: 06/05/2001
• Issued: 03/14/2006
• Est. Priority Date: 06/05/2001
• Status: Expired due to Term

• Current Assignee: Global OLED Technology LLC (LG Display Co., Ltd.)
• Original Assignee: Eastman Kodak Company
• Inventors: Siwinski, Michael J.
• Primary Examiner(s): Awad, Amr A.
• Application Number:
  US09/874,128
• Publication Number:
  US 20020186214A1
• Time in Patent Office: 1,743 Days
• Field of Search: 345/82, 345/83, 345/76, 345/211, 315/169.1, 315/169.2, 315/169.3
• US Class Current: 345/83
• CPC Class Codes: G09G 2300/0452 Details of colour pixel setup, e.g. pixel composed of a red, a blue and two green components
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2340/0428 Gradation resolution change
• CPC Class Codes: G09G 3/20 for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
• CPC Class Codes: G09G 3/3208 organic, e.g. using organic light-emitting diodes [OLED]
• CPC Class Codes: G09G 3/3225 using an active matrix
• CPC Class Codes: G09G 5/028 Circuits for converting colour display signals into monochrome display signals
• CPC Class Codes: H04W 52/0261 managing power supply demand, e.g. depending on battery level
• CPC Class Codes: H04W 52/027 by controlling a display operation or backlight unit
• CPC Class Codes: H10K 59/351 comprising more than three subpixels, e.g. red-green-blue-white [RGBW]
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A method of saving power in a color organic electroluminescent display of the type having color emitting elements with different light emitting efficiencies, includes the steps of: providing a organic electroluminescent color display having colored light emitting elements and white light emitting elements; converting at least a portion of a color digital image to be displayed on the display to a monochrome image; and displaying the monochrome image portion using only the white light emitting elements.

Claims

1. A method of saving power in a color organic electroluminescent display of the type having color emitting elements with different light emitting efficiencies, comprising the steps of:

a) providing an organic electroluminescent color display having colored light emitting elements and white light emitting elements having light emitting efficiencies greater than at least one of the colored light emitting elements;

b) converting at least a portion of a color digital image to be displayed on the display to a monochrome image; and

c) displaying the monochrome image portion using only the white light emitting elements whereby power is saved.

2. The method claimed in claim 1, wherein the display is in a battery powered device, and further comprising the step of monitoring the power level of the battery, and converting to a power saving mode of operation when the battery power reaches a predetermined level.

3. The method claimed in claim 1, further comprising the steps of:

providing a battery saving mode switch on a device that includes the color organic electroluminescent display, and switching to a battery saving mode using the mode switch.

4. The method claimed in claim 1, wherein the step of converting a color digital image to a monochrome digital image comprises combining 5/16, 9/16, and 2/16 of the red, green and blue color signals, respectively.

5. A color organic electroluminescent display, comprising:

a) a plurality of differently colored light emitting elements having different light emitting efficiencies and white light emitting elements having light emitting efficiencies greater than at least one of the colored light emitting elements;

b) a digital image processing circuit for converting at least a portion of a color digital image to be displayed on the display to a monochrome image; and

c) means for displaying the monochrome portion of the image using only the white light emitting elements whereby power is saved.

6. The display claimed in claim 5, wherein the display is in a battery powered device, and further comprising a power monitor for monitoring the power level of the battery, and a control circuit connected to power monitor for converting the display to a power saving mode of operation when the battery power reaches a predetermined level.

7. The display claimed in claim 5, further comprising a battery saving mode switch connected to the control circuit for switching to a battery saving mode.

8. The display claimed in claim 5, wherein the digital image processing circuit converts a color digital image to a monochrome digital image by combining 5/16, 9/16, and 2/16 of the red, green and blue color signals, respectively.

9. An OLED device, comprising:

a) a pixel site including a plurality of individually addressable light emitting elements including a light emitting element for emitting white light and one or more light emitting elements for emitting colored light; and

b) the white light emitting element having a light emitting efficiency at least twice that of at least one of the colored light emitting elements.

10. A method of saving power in an OLED display device, comprising:

a) providing an OLED display having pixel sites with colored light emitting elements and white light emitting elements, the white light emitting element having a light emitting efficiency at least twice that of at least one of the colored light emitting elements;

b) converting at least a portion of a digital color image signal to a power saving digital image signal using the white light emitting elements; and

c) driving the OLED display with the power saving digital image signal.