Light emitting display device with current control

• Main Author: TAISUKE NAKAMURA
• Format: Patent
• Language: English
• Published: 26.07.2000
• Edition: 7
• Subjects: ADVERTISING; ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICESUSING STATIC MEANS TO PRESENT VARIABLE INFORMATION; CRYPTOGRAPHY; DEVICES OR ARRANGEMENTS, THE OPTICAL OPERATION OF WHICH ISMODIFIED BY CHANGING THE OPTICAL PROPERTIES OF THE MEDIUM OF THEDEVICES OR ARRANGEMENTS FOR THE CONTROL OF THE INTENSITY,COLOUR, PHASE, POLARISATION OR DIRECTION OF LIGHT, e.g.SWITCHING, GATING, MODULATING OR DEMODULATING; DISPLAY; DISPLAYING; EDUCATION; ELECTRIC HEATING; ELECTRIC LIGHTING NOT OTHERWISE PROVIDED FOR; ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; FREQUENCY-CHANGING; LABELS OR NAME-PLATES; NON-LINEAR OPTICS; OPTICAL ANALOGUE/DIGITAL CONVERTERS; OPTICAL LOGIC ELEMENTS; OPTICS; PHYSICS; SEALS; SIGNS; TECHNIQUES OR PROCEDURES FOR THE OPERATION THEREOF

A display device comprises a plurality of light emitters 1, 2, 3, each of which is a different colour. A current controller 14 is used to ensure that the sum of currents flowing through the light emitters is maintained at a constant level. This ensures that the brightness of the image is maintained at a constant level. A method of controlling such a display device is disclosed. A further method is also disclosed where two out of three light emitters are used to create a fourth colour and the fourth colour is changed by controlling the current flowing through at least one of the emitters. The light emitters may be light emitting diodes. The display may be used as a back-light, or may be part of a portable electronic device.