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Browse Prior Art Database

Brightness and Color Temperature Control on Thin Film Transistor/Liquid Crystal Display

IP.com Disclosure Number: IPCOM000118844D
Original Publication Date: 1997-Aug-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 1 page(s) / 21K

Publishing Venue

IBM

Related People

Matino, H: AUTHOR

Abstract

Disclosed is a control method of brightness and/or color temperature Thin Film Transistor/Liquid Crystal Display (TFT/LCD) by duty cycle control of Red/Green/Blue (R/G/B) light emitting diodes using fusing for the back light.

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Brightness and Color Temperature Control on Thin Film Transistor/Liquid
Crystal Display

      Disclosed is a control method of brightness and/or color
temperature Thin Film Transistor/Liquid Crystal Display (TFT/LCD) by
duty cycle control of Red/Green/Blue (R/G/B) light emitting diodes
using fusing for the back light.

      The Figure shows an example of the current waveform of Light
Emitting Diodes (LEDs) in which R/LED is the red light emitting
diode, G/LED is the green light emitting diode, and B/LED is the blue
light emitting diode.  Total brightness is controlled by the duty
which is 33.3% maximum for each diode.  Lower brightness is given by
the lower duty cycle.  The ratio of R/G/B chooses the color
temperature and white  balance.  Thus, the color temperature would be
changed by the controlling  of R/G/B ratio.