An exemplary backlight control circuit ( 20 ) includes at least two sampling circuits ( 21 ), at least two feedback circuits ( 22 ), and a PWM IC ( 23 ). Each of the sampling circuits includes a sampling output ( 210 ) and a backlight lamp ( 211 ). The PWM IC includes a current sense pin ( 230 ). The at least two feedback circuits correspond to the at least two sampling circuits, respectively. Each of the feedback circuits includes a resistor ( 222 ) and a diode ( 223 ) electrically coupled in parallel. The sampling output is configured to output a first voltage when the backlight lamp is in a normal working state, and output a second voltage when the backlight lamp has an open circuit. One terminal of the diode is electrically coupled to the sampling output of a corresponding one of the sampling circuits, and an opposite terminal of the diode is electrically coupled to the current sense pin.

Claims

13 · 1 independent · depth 5

13 granted claims

›1.independentA backlight control circuit, comprising:nat least two sampling circuits, each of the sampling circuits comprising a sampling output and a first backli…+12

›2.↳ 1The backlight control circuit as claimed in claim 1, wherein each of the sampling circuits further comprises a second backlight lamp, and the first an…d2+5

›3.↳ 2The backlight control circuit as claimed in claim 2, wherein each of the sampling circuits further comprises a first diode and a sampling resistor, an…d3+3

›7.↳ 2The backlight control circuit as claimed in claim 2, wherein each of the sampling circuits further comprises a coupling capacitor, and in each of the …d3

›8.↳ 1The backlight control circuit as claimed in claim 1, further comprising an integrating capacitor, wherein the current sense pin of the PWM IC is groun…d2+1

›10.↳ 1The backlight control circuit as claimed in claim 1, wherein the first voltage is a high voltage and the second voltage is a low voltage.d2

›11.↳ 1The backlight control circuit as claimed in claim 1, wherein said one terminal of the diode of each of the feedback circuits that is electrically coup…d2

›12.↳ 1The backlight control circuit as claimed in claim 1, wherein a resistance of the resistor of each of the feedback circuits is in the range from 0.1 KΩ…d2

›13.↳ 1The backlight control circuit as claimed in claim 1, wherein a breakdown voltage of the diode of each of the feedback circuits is greater than 10V.d2

Classifications

4 codes

IPC · International Patent Classification

Section G — Physics

G05F1/00

USPC · US Patent Classification

315/307305/291305/308

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2.5 y

911 days filing → grant

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non-final + final

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1 RCE

Examiner

Douglas W Owens

art unit 2821 · TC 2800

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1 priority documents

›Priority documents — 1

Type	Document	Date
related publication	US 20080001555 A1	3 Jan 2008

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