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Patent Issued for Optical Touch Circuit and Liquid Crystal Display Device Using Same

June 4, 2014



By a News Reporter-Staff News Editor at Journal of Engineering -- From Alexandria, Virginia, VerticalNews journalists report that a patent by the inventors Cheng, Yi-Ru (Hsin-Chu, TW); Hsu, Ya-Ling (Hsin-Chu, TW); Chung, Yueh-Hung (Hsin-Chu, TW); Huang, Hsueh-Ying (Hsin-Chu, TW), filed on June 7, 2012, was published online on May 20, 2014.

The patent's assignee for patent number 8730211 is AU Optronics Corp. (Hsin-Chu, TW).

News editors obtained the following quote from the background information supplied by the inventors: "At present, the touch panel generally has several types, such as a resistive type, a capacitive type, an optical type, an electromagnetic type, an ultrasonic wave type, and a LCD in-cell type that has three types of resistive, capacitive and optical. In a display device with an in-cell optical touch panel, a leakage current difference caused by different irradiation light intensities is used to determine that optical sensing elements in the in-cell optical touch panel whether are turned on or not and then serves as a basis for judging the in-cell optical touch panel whether is touched or not.

"For example, the optical sensing element may include a thin film transistor (TFT). A TFT leakage current of the optical sensing element in cases that being touched by finger, being irradiated by ambient light and being touched (also being irradiated) by an light pen correspondingly may have a first current value, a second current value and a third current value. Thus, when the optical sensing element receives a large irradiated light intensity, the TFT leakage current Ids is consequently large, that is, the first current value is less than the second current value, and further less than the third current value. The charge difference generated by the difference of the TFT leakage currents is converted to be an output voltage through an integrator, and the output voltage value then is judged for determining whether the in-cell optical touch panel is touched or not.

"Some of the present touch sensing manners still adopt(s) a differential sensing principle for judgment. Referring to FIG. 1, a source driver 12, touch sensors 16, gate drivers 14 and scanning sensors 18 are respectively disposed at the upside, the underside, the left side and the right side of the LCD. Generally, when a light stylus/pen 101 irradiates at an area of a liquid crystal panel 10, the touch sensors 16 would sense the change of voltage levels at the irradiated area with a high level and a low level, and the high level and the low level together form a group of judging signal as a basis for judging if the LCD device is touched or not by the light pen 10. However, when the light pen 10 irradiates at an edge of the liquid crystal panel 10, the touch sensors 16 only can sense the high level which would cause that the touch sensor 16 misjudges resulting from the incomplete judging signal."

As a supplement to the background information on this patent, VerticalNews correspondents also obtained the inventors' summary information for this patent: "An optical touch circuit includes an optical sensing unit, a first signal readout unit, a touch reference unit, a second signal readout unit, and a touch sensing unit. The optical sensing unit is turned on or turned off according to an irradiation light intensity and accordingly generates a first signal including a first voltage and a second voltage. The first signal readout unit is electrically coupled to the optical sensing unit. The first signal readout unit is turned on or turned off according to a first operation timing sequence and accordingly outputs the first signal. The touch reference unit is disposed at a side of the optical sensing unit and is used for providing a reference voltage. The second signal readout unit is electrically coupled to the touch reference unit. The second signal readout unit is turned on or turned off according to a second operation timing sequence and accordingly outputs the reference voltage. The touch sensing unit is electrically coupled to the first signal readout unit and the second signal readout unit. The touch sensing unit uses a voltage difference between the first signal and the reference voltage as a basis to determine that whether the optical touch circuit is touched or not.

"In another aspect, a liquid crystal display device includes a frame, a plurality of scan lines, a plurality of data lines, a plurality of display pixel units, optical touch circuits, a gate driving unit and a scan sensing unit. The frame is used for defining a border of the liquid crystal display device. The plurality of scan lines are disposed in a region surrounded by the frame. The plurality of data lines are disposed in the region surrounded by the frame and arranged crossing over with the plurality of scan lines. The plurality of display pixel units are disposed in the region surrounded by the frame and electrically coupled to the respective scan lines and data lines. The optical touch circuit(s) is/are disposed in the region surrounded by the frame. The optical touch circuit each include an optical sensing unit, a first signal readout unit, a touch reference unit, a second signal readout unit, and a touch sensing unit. The optical sensing unit is turned on or turned off according to an irradiation light intensity and accordingly generates a first signal. The first signal includes a first voltage and a second voltage. The first signal readout unit is electrically coupled to the optical sensing unit. The first signal readout unit is turned on or turned off according to a first operation timing sequence and accordingly outputs the first signal. The touch reference unit is disposed at a side of the optical sensing unit and is used for providing a reference voltage. The second signal readout unit is electrically coupled to the touch reference unit. The second signal readout unit is turned on or turned off according to a second operation timing sequence and accordingly outputs the reference voltage. The touch sensing unit is electrically coupled to the first signal readout unit and the second signal readout unit. The touch sensing unit uses a voltage difference between the first signal and the reference voltage as a basis to determine that if the corresponding optical touch circuit is touched or not. At least one of the touch reference units of the optical touch circuits is disposed at a position closer to the frame than the optical sensing units of the optical touch circuits. The gate driving unit is disposed in the region surrounded by the frame and electrically coupled to the plurality of scan lines. The scan sensing unit is disposed in the region surrounded by the frame. The scan sensing unit is electrically coupled to the optical touch circuits so as to provide a first operation timing sequence and a second operation timing sequence for each of the optical touch circuits.

"For above and another objectives, features, and advantages of the present disclosure being better understood and legibly, accompanying embodiments together with the drawings are particularized."

For additional information on this patent, see: Cheng, Yi-Ru; Hsu, Ya-Ling; Chung, Yueh-Hung; Huang, Hsueh-Ying. Optical Touch Circuit and Liquid Crystal Display Device Using Same. U.S. Patent Number 8730211, filed June 7, 2012, and published online on May 20, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=66&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=3273&f=G&l=50&co1=AND&d=PTXT&s1=20140520.PD.&OS=ISD/20140520&RS=ISD/20140520

Keywords for this news article include: AU Optronics Corp.

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Source: Journal of Engineering


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