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Patent Issued for Driving Circuit of Light Emitting Diode and Ghost Phenomenon Elimination Circuit

July 23, 2014



By a News Reporter-Staff News Editor at Electronics Newsweekly -- From Alexandria, Virginia, VerticalNews journalists report that a patent by the inventors Lin, Chun-Fu (Hsinchu, TW); Kuo, Chun-Ting (Pingtung County, TW); Hsieh, Cheng-Han (Hsinchu County, TW), filed on July 20, 2012, was published online on July 8, 2014.

The patent's assignee for patent number 8773414 is My-Semi Inc. (Hsinchu County, TW).

News editors obtained the following quote from the background information supplied by the inventors: "The present invention relates to a driving circuit of a light emitting diode; in particular, to a driving circuit having the function of eliminating ghost phenomenon.

"Light emitting diodes (LEDs) are small, power saving, and durable components. Along with the maturity of the manufacturing processes and cost reducing, more and more products are using light emitting diode as a light source. The light emitting diode is used in several kinds of equipments, such as headlight lamp of a vehicle, traffic light, word displayer, signboard, large screen video display, simple and building illumination, and LCD backlight.

"Please refer to FIG. 1. FIG. 1 shows a schematic diagram of a conventional driving device of a light emitting diode. The driving device of the light emitting diode mainly includes a driving line selector 110 and a driving circuit 120. The driving line selector 110 may select the conducted driving lines L1 and L2. Every driving line L1 or L2 is connected with several respective light emitting diodes D1.about.D4, as shown in FIG. 1. The driving circuit 120 is for controlling driving currents of the light emitting diodes D1.about.D4, and has several current driving terminals OUT1 and OUT2 which correspond to different light emitting diodes D1.about.D4. In detail, the driving circuit 120 has a current source circuit for controlling the currents flowing into the current driving terminals OUT1 and OUT2, in order to control the brightness of the light emitting diodes D1.about.D4.

"In the multi scanning driving structure, such as two scanning or four scanning, the driving line selector 110 must scan several sets of light emitting diodes in one single frame period. When the scanning processes are switching, a ghost phenomenon may occur because of the parasitic capacitance of the light emitting diodes, and the phenomenon may get worse due to the increase of the switch actions."

As a supplement to the background information on this patent, VerticalNews correspondents also obtained the inventors' summary information for this patent: "The object of the present invention is to provide a driving circuit of a light emitting diode (LED) and a ghost phenomenon elimination circuit thereof. The driving circuit may pull up the voltage level of a current driving terminal to a high voltage level during a black insertion period, in order to reduce the problem of ghost phenomenon of the light emitting diode.

"In order to achieve the aforementioned objects, according to an embodiment of the present invention, a driving circuit of the light emitting diode is disclosed. The driving circuit includes a current driving unit and a ghost phenomenon elimination circuit. The current driving unit has at least one current driving terminal, and the ghost phenomenon elimination circuit includes a ghost phenomenon elimination unit and a counter unit. The ghost phenomenon elimination unit is coupled to the current driving terminal, for adjusting the voltage level of the current driving terminal according to an enable signal. The counter unit is coupled to the ghost phenomenon elimination unit, for counting a gray scale clock signal, in order to determine a black insertion period and output the enable signal to the ghost phenomenon elimination unit during the black insertion period. After that, the ghost phenomenon elimination unit may pull up the voltage level of the current driving terminal to a high voltage level according to the enable signal.

"Seeing from another aspect, the present invention provides a ghost phenomenon elimination circuit which is associated with a driving circuit of a light emitting diode. A current driving unit of the driving circuit has at least one current driving terminal, and an output timing of the current driving terminal corresponds to a gray scale clock signal. The ghost phenomenon elimination circuit includes a ghost phenomenon elimination unit and a counter unit. The ghost phenomenon elimination unit is coupled to the current driving terminal, for adjusting the voltage level of the current driving terminal according to an enable signal. The counter unit is coupled to the ghost phenomenon elimination unit for counting a gray scale clock signal, in order to determine a black insertion period and output the enable signal to the ghost phenomenon elimination unit during the black insertion period. After that, the ghost phenomenon elimination unit may pull up the voltage level of the current driving terminal to a high voltage level according to the enable signal.

"On the basis of the above, the present invention determines the black insertion period by counting the gray scale clock signal, and pulls up the voltage of the current driving terminal during the black insertion period, for speeding up the time of turning off the light emitting diode, in order to eliminate the problem of ghost phenomenon.

"For further understanding of the present disclosure, reference is made to the following detailed description illustrating the embodiments and examples of the present disclosure. The description is only for illustrating the present disclosure, not for limiting the scope of the claim."

For additional information on this patent, see: Lin, Chun-Fu; Kuo, Chun-Ting; Hsieh, Cheng-Han. Driving Circuit of Light Emitting Diode and Ghost Phenomenon Elimination Circuit. U.S. Patent Number 8773414, filed July 20, 2012, and published online on July 8, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=8773414.PN.&OS=PN/8773414RS=PN/8773414

Keywords for this news article include: Electronics, My-Semi Inc, High Voltage, Light-emitting Diode.

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Source: Electronics Newsweekly


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