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Researchers Submit Patent Application, "Led Driving Apparatus and Operating Method Thereof", for Approval

June 18, 2014



By a News Reporter-Staff News Editor at Electronics Newsweekly -- From Washington, D.C., VerticalNews journalists report that a patent application by the inventors Chu, Chih-Wei (New Taipei, TW); Lee, Yu-En (New Taipei, TW); Chou, Shu-Kuang (New Taipei, TW), filed on November 20, 2013, was made available online on June 5, 2014.

The patent's assignee is Raydium Semiconductor Corporation.

News editors obtained the following quote from the background information supplied by the inventors: "The invention relates to the driving of a light-emitting diode (LED); in particular, to an AC-to-DC LED driving apparatus for illumination and operating method thereof.

"Recently, LED has been widely used in many applications. In a conventional linear LED driving circuit, no matter single segment driving or multiple segments driving is used, when the input voltage is smaller than a forward voltage of the LED, the current passing through the LED will be zero. In order to reach average current having best illumination efficiency, the LED current should be increased and the power and temperature will be also increased.

"If a LED string has a first light-emitting diode, a second light-emitting diode, and a third light-emitting diode coupled in series, as shown in FIG. 1, in the periods of .DELTA.T1, .DELTA.T2, and .DELTA.T3, a first LED current I.sub.LED1, a second LED current I.sub.LED2, and a third LED current I.sub.LED3 are zero respectively. Because the first LED current I.sub.LED1, the second LED current I.sub.LED2, and the third LED current I.sub.LED3 are all zero in the period of .DELTA.T1, it means that the first light-emitting diode LED1, the second light-emitting diode LED2, and the third light-emitting diode LED3 fail to illuminate in the period of .DELTA.T1, so that the LED string will generate flicker of 120 Hz.

"Therefore, the invention provides a LED driving apparatus and operating method thereof to solve the above-mentioned problems occurred in the prior arts."

As a supplement to the background information on this patent application, VerticalNews correspondents also obtained the inventors' summary information for this patent application: "An embodiment of the invention is a LED driving apparatus. In this embodiment, the LED driving apparatus includes a power, at least one LED string, a LED control unit, and an input voltage detection circuit. The at least one LED string is coupled to the power and includes a plurality of LEDs coupled in series. The LED control unit is coupled to the at least one LED string and used for controlling the operation of the plurality of LEDs.

"The input voltage detection circuit is coupled to two ends of at least one LED of the plurality of LEDs respectively and used to judge whether an input voltage is lower than a LED conducting voltage. The input voltage detection circuit includes a charging capacitance to be charged when the at least one LED string is conducted. If the judged result of the input voltage detection circuit is yes, the input voltage detection circuit will control the charging capacitance having a charging voltage to discharge to the at least one LED string.

"Another embodiment of the invention is a method of operating a LED driving apparatus. In this embodiment, the LED driving apparatus includes a power, at least one LED string, a LED control unit, and an input voltage detection circuit. The at least one LED string includes a plurality of LEDs coupled in series. The input voltage detection circuit is coupled to two ends of at least one LED of the plurality of LEDs respectively.

"The method includes steps of: (a) the LED control unit controlling the operation of the plurality of LEDs; (b) the input voltage detection circuit judging whether an input voltage is lower than a LED conducting voltage; if the judged result of the input voltage detection circuit is yes, the input voltage detection circuit will control the charging capacitance having a charging voltage to discharge to the at least one LED string.

"Compared to the prior art, the LED driving apparatus and the LED driving apparatus operating method of the invention can detect whether an input voltage is lower than a LED conducting voltage through the input voltage detection circuit, if yes, the charging capacitance having a charging voltage will be controlled to discharge to a part of the LEDs, so that there is still some current passing through the part of the LEDs and the part of the LEDs will continuously illuminate instead of no LED illuminating during certain period of time as prior art. Therefore, the LED driving apparatus of the invention can effectively improve the flicker occurred in the LED string of the prior art and enhance the illumination efficiency of the LED string in every AC cycle.

"The advantage and spirit of the invention may be understood by the following detailed descriptions together with the appended drawings.

BRIEF DESCRIPTION OF THE APPENDED DRAWINGS

"FIG. 1 illustrates a timing diagram of the LED currents of the first LED, the second LED, and the third LED coupled in series in the LED string of the prior art.

"FIG. 2 illustrates a schematic diagram of the LED driving apparatus in an embodiment of the invention.

"FIG. 3 illustrates a schematic diagram of the LED driving apparatus in another embodiment of the invention.

"FIG. 4 illustrates a timing diagram of the LED currents of the first LED, the second LED, and the third LED coupled in series in the LED string of the invention.

"FIG. 5 illustrates a flow chart of the LED driving apparatus operating method in another embodiment of the invention.

"FIG. 6 illustrates a flow chart of the LED driving apparatus operating method in another embodiment of the invention.

"FIG. 7 illustrates a flow chart of the LED driving apparatus operating method in another embodiment of the invention."

For additional information on this patent application, see: Chu, Chih-Wei; Lee, Yu-En; Chou, Shu-Kuang. Led Driving Apparatus and Operating Method Thereof. Filed November 20, 2013 and posted June 5, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=4524&p=91&f=G&l=50&d=PG01&S1=20140529.PD.&OS=PD/20140529&RS=PD/20140529

Keywords for this news article include: Electronics, Light-emitting Diode, Raydium Semiconductor Corporation.

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Source: Electronics Newsweekly


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