Source: http://www.google.com/patents/US7652655?dq=6,205,432
Timestamp: 2017-12-16 17:07:16
Document Index: 665652748

Matched Legal Cases: ['§119', 'Application No. 200410103347', 'Application No. 10', 'Application No. 2005', 'Application No. 2005', 'Application No. 200410103347', 'Application No. 2005']

Patent US7652655 - Backlight driver circuit and liquid crystal display device having the same - Google Patents
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...http://www.google.com/patents/US7652655?utm_source=gb-gplus-sharePatent US7652655 - Backlight driver circuit and liquid crystal display device having the same
Publication number US7652655 B2
Application number US 11/322,261
Also published as US20060187181
Publication number 11322261, 322261, US 7652655 B2, US 7652655B2, US-B2-7652655, US7652655 B2, US7652655B2
Patent Citations (24), Non-Patent Citations (6), Referenced by (8), Classifications (13), Legal Events (5)
US 7652655 B2
a backlight driver for supplying R, G and B driving currents and R, G and B pulse width modulation (PWM) signals to the backlight unit so as to selectively cause generation of a previous state, activation of the R backlight, activation of the G backlight and activation of the B backlight, and controlling brightness and chromaticity of the R, G and B backlights; and
a driving current generator for supplying R, G and B driving currents to the R, G and B backlights, respectively, so as to cause the R, G and B backlights, respectively, to emit light with predetermined brightness;
a pulse width modulation (PWM) signal generator for supplying R, G and B PWM signals to the R, G and B backlights, respectively, to adjust chromaticity of the light emitted from the R, G and B backlights, respectively; and
a light emitting diode (LED) controller for supplying a control signal to the PWM signal generator so as to selectively cause generation of a previous state, activation of the R backlight to emit light in a first sub-frame, activation of the G backlight to emit light in a second sub-frame, and activation of the B backlight to emit light in a third sub-frame.
12. The backlight driver circuit according to claim 8, wherein the R backlight comprises two red light emitting diodes connected in series with each other, the G backlight comprises one green light emitting diode, and the B backlight comprises two blue light emitting diodes connected in parallel with each other.
13. The backlight driver circuit according to claim 8, wherein the control signal is a two-digit binary signal having four states, each corresponding to a respective one of the generation of a previous state, the activation of the R backlight, the activation of the G backlight, and the activation of the B backlight.
a backlight unit for having R, G and B backlights for sequentially emitting light toward the LCD panel in one frame divided into at least two sub-frames; and
a backlight driver for supplying R, G and B driving currents and R, G and B pulse width modulation (PWM) signals to the backlight unit, and controlling brightness and chromaticity of the R, G and B backlights;
wherein the backlight driver comprises:
a PWM signal generator for supplying the R, G and B PWM signals to the R, G and B backlights, respectively, and for adjusting the chromaticity of the light emitted from each of the R, G and B backlights; and
15. The LCD device according to claim 14, wherein the backlight driver further comprises a driving current generator for supplying R, G and B driving currents to the R, G and B backlights, respectively, so as to cause the R, G and B backlights, respectively, to emit light with predetermined brightness.
16. The LCD device according to claim 15, wherein the driving current generator comprises a register for storing R, G and B data corresponding to the R, G and B driving currents, respectively.
17. The LCD device according to claim 14, wherein the PWM signal generator comprises a register for storing R, G and B data corresponding to the R, G and B PWM signals, respectively.
18. The LCD device according to claim 14, wherein the R, G and B PWM signals are used in adjusting the chromaticity of the R, G and B backlights, respectively, so as to adjust a white balance.
19. The LCD device according to claim 14, further comprising a timing controller directly connected to the scan driver, the source driver and the backlight driver for directly controlling the scan driver, the source driver and the backlight driver.
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.
Typically, one frame driven at 60 Hz has a period of 16.7 ms (i.e., 1/60 s). In the field sequential LCD, one frame is divided into three sub-frames, and thus one sub-frame has a period of 5.56 ms (i.e., 1/180 s). This period corresponding to one sub-frame is so short that the human eyes cannot detect a field change. Consequently, a viewer merely recognizes a mixture of R, G and B colored lights in the period of 16.7 ms corresponding to one frame.
Red light −20~−5 20 32.5 2.2
emitting −5~25 20 32.5 2.0
Green light −20~−5 45 37.5 3.1
emitting −5~25 45 37.5 3.0
Blue light −20~−5 15 40 3.3
emitting −5~25 15 40 3.25
Referring to FIG. 5, the driving current generator 510 supplies a driving current, e.g., a forward driving current ILED of 35 mA, to the R backlight 410 in the R sub-frame. At this 11 point, the first control signal CT0 having a high level and the second control signal CT1 having a low level (i.e., ‘10’, refer to FIG. 5) are transmitted to the LED controller 530 so as to cause the R backlight 410 to emit light. Then, the LED controller 530 supplies an output signal for driving the R backlight 410 of the backlight unit 400 to the PWM signal generator 520. Then, the PWM signal generator 520 generates the PWM signal RPWM for driving the R backlight 410 according to the output signal of the LED controller 530. Thus, the R backlight 410 receives the forward current ILED applied to the R light emitting diodes RLED1 and RLED2 and the driving current RIf corresponding to the PWM signal RPWM, as shown in FIG. 5, thereby emitting red light having predetermined chromaticity and brightness. In this embodiment, the R backlight 410 includes two R light emitting diodes RLED1 and RLED2 connected in series with each other, and the driving current generator 510 supplies a current of 35 mA to the R backlight 410. Alternatively, the R backlight 410 may include two R light emitting diodes RLED1 and RLED2 connected in parallel with each other, in which case the driving current generator 510 supplies a current of 70 mA to the R backlight 410.
JP2000206486A Title not available
JP2000214435A Title not available
JP2002111786A Title not available
JP2003107424A Title not available
JP2004309509A Title not available
JP2004341206A Title not available
KR19990076777A Title not available
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WO2004090997A1 * Mar 26, 2004 Oct 21, 2004 Hunet Inc. Led drive device and led drive method
1 Certificate of Patent from the Chinese Patent Office issued in corresponding Applicant's Chinese Patent Application No. 200410103347.5 dated Dec. 31, 2008 with Request for Entry of the Accompanying Document.
2 Korean Notice of Allowability corresponding to Korean Patent Application No. 10-2005-0014698, mailed on Jun. 8, 2007.
3 Korean Office Action for Korean Patent Application No. 2005-0014698 issued on Aug. 2, 2006.
4 Korean Office Action for Korean Patent Application No. 2005-0014698 issued on Dec. 13, 2006.
5 Office action from the Patent Office of the People's Republic of China issued in corresponding Applicant's Chinese Patent Application No. 200410103347.5 dated Apr. 6, 2007.
6 The Office Action from the Japanese Patent Office issued in Applicant's corresponding Japanese Patent Application No. 2005-234809 dated Sep. 24, 2008.
US8154507 * Jan 22, 2009 Apr 10, 2012 Rohm Co., Ltd. Back light system and liquid crystal display device using the back light system
US20090189844 * Jan 22, 2009 Jul 30, 2009 Rohm Co., Ltd. Back light system and liquid crystal display device using the back light system
U.S. Classification 345/102, 345/100, 345/98, 345/204
Cooperative Classification G09G2320/0666, G09G2310/0235, G09G2330/021, G09G2320/0633, G09G2320/064, G09G3/3413, G09G2320/041