Back lighting device, its driving method, and liquid crystal display with said device
A technology for backlighting and equipment, applied in the field of backlighting equipment, its driver, and liquid crystal displays equipped with the equipment, can solve the problems of low thermal efficiency, electromagnetic interference, and low brightness, and achieve high thermal efficiency, uniform brightness, and high brightness. Effect
Inactive Publication Date: 2003-11-26
SAMSUNG DISPLAY CO LTD
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Problems solved by technology
[0055] However, since the above-mentioned EEFL is driven by a high-frequency signal of several megahertz, problems of electromagnetic interference (EMI) due to high frequency, low thermal efficiency and problems due to high-frequency power supply occur, and these EEFLs cannot be used as backlights. light source in the device
[0056] In other words, when the EEFL is driven by an inverter generating a sine wave to drive a CCFL, since the wall current cannot be effectively controlled, the EEFL has very low brightness and very low thermal efficiency compared to an EEFL with a glass tube
[0057] Similarly, when LC resonant converter is used in EEFL to drive CCFL, EEFL cannot be used as the light source of backlighting equipment because the brightness is very low and the thermal efficiency is very low
Method used
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[0103] Hereinafter, a floating type lamp driving method and a ground type lamp driving method will be briefly explained.
[0104] Generally speaking, when driving an EIFL in which an external electrode is formed at one end of a glass tube, or an EEFL in which an external electrode is formed at both ends of the glass tube, depending on the power supply section, that is, the converter for applying an AC power signal to the lamp, use Floating or grounded fluorescent lamp driving method. When the lamps are driven by applying the same tube current to the lamps in both fluorescent lamp driving methods, the voltage across each lamp is the same, as shown in Table 2.
[0105] voltage across the lamp
between (+) and (-) in the hot electrode
potential difference between
Between (+) and (-) in the cold electrode
potential difference between
grounded
1000V
2000V
0V
floating
1000V
1000V
1000V
[0106] Hereinafte...
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A backlight assembly has a lamp driving device for driving external electrode fluorescent lamps (EEFLs) parallel connected each other. The lamp driving device includes a power switch transistor, a diode, an inverter and a PWM controller. The transistor converts external DC power signal into pulse power signal based on switching signal, the diode prevents rush current from flowing into the transistor. The inverter converts the pulse power signal into AC power signal, raises voltage level of the AC power signal, and provides the lamps with the raised AC power signal. The PWM controller is activated by external on / off signal to provide the transistor with the switching signal so as to regulate voltage level of the AC power signal. The EEFLs can maintain a constant current level, and the backlight assembly can have characteristics of uniform luminance, high luminance and high heat efficiency.
Description
[0001] Cross-application of related applications [0002] This application claims priority from Korean Patent Application No. 2002-27461 filed on May 17, 2002, the entire contents of which are incorporated herein by reference. technical field [0003] The present invention relates to a backlight equipped with an external electrode fluorescent lamp, a driving method thereof, and a liquid crystal display equipped with the same. Background technique [0004] Generally, flat panel displays are classified into emissive display devices and non-emissive display devices. Emissive display devices include cathode ray tubes (CRTs), plasma display panels (PDPs), electroluminescence display devices (ELDs), vacuum fluorescent display devices (VFDs), light emitting diodes (LEDs), and the like. Non-emissive display devices include liquid crystal display (LCD) devices. [0005] LCD devices are passive flat panel display devices in which images are displayed using light from an external lig...
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IPC IPC(8): G02F1/13357F21V8/00F21Y103/00G02F1/133G09G3/34H01J65/00H05B41/24H05B41/282H05B41/392
CPCH05B41/2824G02F1/133604H01J65/046Y02B20/186G02F2001/133612G02F1/133612Y02B20/00G02F1/133
Inventor 俞炯硕姜圣哲姜文拭李正焕李根雨
Owner SAMSUNG DISPLAY CO LTD