Backlight assembly having external electrode fluorescent lamp, method of driving thereof and liquid crystal display having the same
First Claim
1. A backlight assembly having an external electrode fluorescent lamp, the backlight assembly comprising:
- a lamp driving means for receiving an external DC power signal and an external dimming signal, converting the external DC power signal into an AC power signal, controlling a voltage level of the AC power signal using the external dimming signal, and raising a voltage level of the AC power signal having the controlled voltage level to produce a raised AC power signal;
a light emitting means having a lamp unit, for generating a light based on the raised AC power signal, the lamp unit including a plurality of parallel-connected external electrode fluorescent lamps, and at least one end of each of the external electrode fluorescent lamps having an external electrode; and
an optical distribution changing means for changing an optical distribution of the light generated from the light emitting means.
1 Assignment
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Accused Products
Abstract
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.
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Citations
44 Claims
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1. A backlight assembly having an external electrode fluorescent lamp, the backlight assembly comprising:
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a lamp driving means for receiving an external DC power signal and an external dimming signal, converting the external DC power signal into an AC power signal, controlling a voltage level of the AC power signal using the external dimming signal, and raising a voltage level of the AC power signal having the controlled voltage level to produce a raised AC power signal;
a light emitting means having a lamp unit, for generating a light based on the raised AC power signal, the lamp unit including a plurality of parallel-connected external electrode fluorescent lamps, and at least one end of each of the external electrode fluorescent lamps having an external electrode; and
an optical distribution changing means for changing an optical distribution of the light generated from the light emitting means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16, 17)
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15. A backlight assembly having an external electrode fluorescent lamp, the backlight assembly comprising:
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a light emitting means having a lamp unit for generating a light, the lamp unit including a plurality of parallel-connected external electrode fluorescent lamps, and an external electrode disposed at least one end of each of the external electrode fluorescent lamps;
a lamp driving means for receiving an external DC power signal and an external dimming signal, converting the external DC power signal into an AC power signal, detecting a level of a current supplied to the lamp unit, controlling a level of a voltage of the AC power signal supplied to the lamp unit based on the external dimming signal and the detected current level, raising a voltage level of the AC power signal having the controlled voltage level to provide the lamp unit with the raised AC power signal so as to control the lamp unit to generate the light using the raised AC power signal; and
an optical distribution changing means for changing an optical distribution of the light generated from the light emitting means. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25)
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26. A backlight assembly having an external electrode fluorescent lamp, the backlight assembly comprising:
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a light emitting means having a lamp unit for generating a light, the lamp unit including a plurality of parallel-connected external electrode fluorescent lamps, an external electrode being disposed at least one end of each of the external electrode fluorescent lamps, and a first end of the lamp unit being connected to a ground;
a lamp driving means for receiving an external DC power signal, converting the external DC power signal into an AC power signal, detecting a level of a current supplied to the lamp unit, controlling a level of a voltage of the AC power signal supplied to the lamp unit based on the detected current level, raising a voltage level of the AC power signal having the controlled voltage level to provide the lamp unit with the raised AC power signal so as to control the lamp unit to generate the light using the raised AC power signal; and
an optical distribution changing means for changing an optical distribution of the light generated from the light emitting means. - View Dependent Claims (27, 28, 29, 30, 31, 33)
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32. A method of driving an external electrode fluorescent lamp in a lamp unit, the lamp unit including a plurality of parallel-connected external electrode fluorescent lamps, and an external electrode disposed at least one end of each of the external electrode fluorescent lamps, the method comprising:
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(a) converting an external dimming signal into an analogue dimming signal;
(b) generating a switching signal based on an external on-off control signal and the analogue dimming signal;
(c) converting an external DC power signal into a pulse power signal based on the switching signal;
(d) converting the pulse power signal into an AC power signal;
(e) raising a voltage level of the AC power signal to produce a raised AC power signal; and
(f) providing the lamp unit with the raised AC power signal. - View Dependent Claims (34, 35)
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36. A method of driving an external electrode fluorescent lamp in a lamp unit, the lamp unit including a plurality of parallel-connected external electrode fluorescent lamps, and an external electrode disposed at least one end of each of the external electrode fluorescent lamps, the method comprising:
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(a) converting an external dimming signal into an analogue dimming signal;
(b) generating a first switching signal based on an external on-off control signal and the analogue dimming signal;
(c) converting an external DC power signal into a pulse power signal based on the first switching signal;
(d) converting the pulse power signal into an AC power signal;
(e) raising a voltage level of the AC power signal to produce a raised AC power signal;
(f) providing a first end of the lamp unit with a first raised AC power signal of the raised AC power signal;
(g) providing a second end of the lamp unit with a second raised AC power signal of the raised AC power signal, the second raised AC power signal having a phase difference of about 180°
with respect to the first raised AC power signal;
(h) detecting a current level of a current supplied to the lamp unit to produce a current level signal; and
(i) generating a second switching signal based on the current level signal, the on-off control signal and the first switching signal, and then returning back to the step (c). - View Dependent Claims (37)
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38. A method of driving an external electrode fluorescent lamp in a lamp unit, the lamp unit including a plurality of parallel-connected external electrode fluorescent lamps, an external electrode disposed at least one end of each of the external electrode fluorescent lamps, and a first end of the lamp unit being connected to a ground, the method comprising:
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(a) converting an external dimming signal into an analogue dimming signal;
(b) generating a first switching signal based on an external on-off control signal and the analogue dimming signal;
(c) converting an external DC power signal into a pulse power signal based on the first switching signal;
(d) converting the pulse power signal into an AC power signal;
(e) raising a voltage level of the AC power signal to produce a raised AC power signal;
(f) providing a second end of the lamp unit with the raised AC power signal;
(g) detecting a current level of a current supplied to the lamp unit to produce a current level signal; and
(h) generating a second switching signal based on the current level signal, the on-off control signal and the first switching signal, and then returning back to the step (c).
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39. A liquid crystal display apparatus comprising:
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a backlight assembly including i) a lamp driving means for receiving an external DC power signal and an external dimming signal, converting the external DC power signal into an AC power signal, controlling a voltage level of the AC power signal using the external dimming signal, and raising a voltage level of the AC power signal having the controlled voltage level to produce a raised AC power signal, ii) a light emitting means having a lamp unit, for generating a light based on the raised AC power signal, the lamp unit including a plurality of parallel-connected external electrode fluorescent lamps, and at least one end of each of the external electrode fluorescent lamps having an external electrode, and iii) an optical distribution changing means for changing an optical distribution of the light generated from the light emitting means; and
a display unit, disposed on the optical distribution changing means, for displaying an image by receiving the light from the light emitting means. - View Dependent Claims (40, 42)
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41. A liquid crystal display apparatus comprising:
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a backlight assembly including i) a light emitting means having a lamp unit for generating a light, the lamp unit including a plurality of parallel-connected external electrode fluorescent lamps, and an external electrode disposed at least one end of each of the external electrode fluorescent lamps ii) a lamp driving means for receiving an external DC power signal and an external dimming signal, converting the external DC power signal into an AC power signal, detecting a level of a current supplied to the lamp unit, controlling a level of a voltage of the AC power signal supplied to the lamp unit based on the external dimming signal and the detected current level, raising a voltage level of the AC power signal having the controlled voltage level to provide the lamp unit with the raised AC power signal so as to control the lamp unit to generate the light using the raised AC power signal, and iii) an optical distribution changing means for changing an optical distribution of the light generated from the light emitting means; and
a display unit, disposed on the optical distribution changing means, for displaying an image by receiving the light from the light emitting means.
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43. A liquid crystal display apparatus comprising:
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a backlight assembly including i) a light emitting means having a lamp unit for generating a light, the lamp unit including a plurality of parallel-connected external electrode fluorescent lamps, an external electrode being disposed at least one end of each of the external electrode fluorescent lamps, and a first end of the lamp unit being connected to a ground, ii) a lamp driving means for receiving an external DC power signal, converting the external DC power signal into an AC power signal, detecting a level of a current supplied to the lamp unit, controlling a level of a voltage of the AC power signal supplied to the lamp unit based on the detected current level, raising a voltage level of the AC power signal having the controlled voltage level to provide the lamp unit with the raised AC power signal so as to control the lamp unit to generate the light using the raised AC power signal, and iii) an optical distribution changing means for changing an optical distribution of the light generated from the light emitting means; and
a display unit, disposed on the optical distribution changing means, for displaying an image by receiving the light from the light emitting means. - View Dependent Claims (44)
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Specification