Backlight driver circuit and liquid crystal display device having the same

Abstract

In a backlight driver circuit and a liquid crystal display (LCD) device employing the same, separate forward driving currents are applied to red (R), green (G) and blue (B) backlights, respectively, thereby overcoming the problem of brightness variation resulting from forward voltage Vf variation in a light emitting diode (LED). The LCD includes: a backlight unit provided with R, G and B backlights for emitting light toward an LCD panel in sequence; and a backlight driver for supplying driving currents and pulse width modulation (PWM) signals to the backlight unit so as to control brightness and chromaticity of the R, G and B backlights. The backlight driver includes: a driving current generator for supplying R, G and B driving currents to the respective R, G and B backlights, and for causing the respective R, G and B backlights to emit light with predetermined brightness; and a PWM signal generator for supplying R, G and B PWM signals to the R, G and B backlights, respectively, so as to adjust the chromaticity of the light emitted from the R, G and B backlights, respectively.

Description

CLAIM OF PRIORITY[0001]This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from an application earlier filed in the Korean Intellectual Property Office on Feb. 22, 2005 and there duly assigned Ser. No. 2005-14698.BACKGROUND OF THE INVENTION[0002]1. Technical Field of the Invention[0003]The present invention relates to a liquid crystal display (LCD) device, and more particularly, to a backlight driver circuit and an LCD device having the same, in which a forward driving current is applied to red (R), green (G), and blue (B) backlights, thereby improving brightness variation in response to a forward voltage Vf applied to a light emitting diode (LED).[0004]2. Related Art[0005]In general, a color liquid crystal display (LCD) device includes: an LCD panel having an upper substrate, a lower substrate, and a liquid crystal disposed between the upper and lower substrates; a driver circuit for driving the LCD panel; and a b...

AI Technical Summary

Benefits of technology

[0011]The present invention also provides a field sequential LCD device having a backlight driver circuit capable of supplying driving currents suitable for respective light emitting diodes, and of reducing power consumption.

[0012]The present invention also provides a filed sequential LCD device having a backlight driver circuit capable of supplying driving currents suitable for respective light emitting diodes, and of maximizing power efficiency.

Problems solved by technology

In this regard, since the same driving voltage is supplied during three sub-frames corresponding to one frame for driving the R, G and B light emitting diodes, the driving voltage generator should generate the highest driving voltage among the driving voltages needed for the R, G and B light emitting diodes, and thus power consumption increases.

Furthermore, since the forward driving voltages supplied to the R, G and B light emitting diodes in each sub-frame vary with temperature, the brightness of each backlight also varies somewhat with temperature, thereby upsetting white balance.