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AssigneeOrise Technology Co., Ltd.
InventorHung Jen Chien
Estimating the term…
The present invention relates to an LED driver, power control circuit and display panel using the same. The LED driver has the function of spread spectrum frequency modulation (SSFM). The circuit topology of the driver includes a power converter, an error amplifier, a feedback circuit, a saw-tooth generator and a driving circuit. The present invention adds the SSFM circuit in the saw-tooth generator to generate a time variant current according to time variant function, so that the saw-tooth wave could be changed by the time variant current as mentioned above. Therefore, the frequency of the driving pulse generated by the LED driver will be varied as time. As the result, the reduction of the electro-magnetic interference (EMI) can be achieved.
A power control circuit, adapted for controlling a power converter to drive a light emitting diode series, wherein the power converter receives a driving pulse outputted from the power control circuit to generate a driving voltage to a first terminal of the light emitting diode series, the power control circuit comprising:
A light emitting diode driver, adapted for driving a light emitting diode series, the light emitting diode driver comprising:
Dependencies are inferred from the claim text.
Drawings are temporarily unavailable. Open the PDF at USPTO
From the US filing history. Foreign family members aren’t listed.
Pulse-control circuits: pulse-width modulation [PWM]
With an active control inside an LED matrix: having LEDs disposed in parallel lines
Switched mode power supply [SMPS]: using boost topology
Driver circuits: dynamic headroom control [DHC]
About 3 years 7 months of term left · ends 10 Jun 2030 (estimated)
This application claims priority of No. 097129991 filed in Taiwan R.O.C. on Aug. 8, 2008 under 35 USC 119, the entire content of which is hereby incorporated by reference.
1. Field of Invention
The invention relates to a power supply technology, more particular to a power supply control circuit with frequency expansion modulation, a light emitting diode (hereinafter referring to as LED) driver and a display module using the same.
The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention.
FIG. 1 is a circuit diagram showing the conventional LED driver circuit.
FIG. 2 is a system block diagram depicting a display module according to an embodiment of the present invention.
The present invention will be apparent from the following detailed description, which proceeds with reference to the accompanying drawings, wherein the same references relate to the same elements.
FIG. 2 is a system block diagram depicting a display module according to an embodiment of the present invention. Referring to the FIG. 2, the display module comprises a transmissive display panel 201 and a backlight module 202. The backlight module 202 is disposed on the back side of the transmissive display panel 201 to provide the transmissive display panel 201 a backlight source. The backlight module 202 usually comprises a light source, a light guide, a diffuser, and so on. The discussion is mainly focused on the light source. In this embodiment, the light source of the backlight module 202 comprises a light emitting diode series and an LED driver of the embodiment of the present invention. The followings are based on the LED driver of the embodiment of the present invention to illustrate the spirit of the present invention.
FIG. 3 is the LED driver circuit diagram according to an embodiment of the present invention. Referring to the FIG. 3, a boost type power converter is an example of the LED driver circuit. The boost type converter has been mentioned in the prior art and will not be discussed here repeatedly. One having ordinary skills in the art may easily understand that the primary difference between the present invention and the traditional circuit is the saw-tooth generator S301. The saw-tooth generator S301 can be mainly divided into a variable current source S302 and a peak detector S303. The variable current source S302 generates a time variant current according to a time variant function. The peak detector S303 generates a time variant saw-tooth voltage according to the value of the time variant current. The following diagrams illustrate a more detailed circuit, so that one having ordinary skills in the art could implement the spirit of the present invention.