Display device including sensing elements and driving method thereof

A display device includes a plurality of touch sensors and a touch sensor controller. The touch sensor controller defines sensing units. Each of the sensing units includes at least two touch sensors. The touch sensor controller generates coordinates information of the sensing unit when all of the touch sensors of the sensing unit are generating an output signal or at least one of the touch sensors of the sensing unit is generating an output signal.

This application claims priority to Korean Patent Application No. 2006-0114022 filed on Nov. 17, 2006, and all the benefits accruing therefrom under 35 U.S.C. §119, the contents of which are herein incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a display device and a driving method thereof and in particular, a display device including sensing elements and a driving method thereof.

2. Description of the Related Art

A touch panel is disposed on a display device, so that a user may touch the touch panel with a hand or other objects so as to select an article displayed via the display device. A selected position is perceived via the touch panel. The display device drives the display panel according to the article corresponding to the position.

The display device including the touch panel needs no input device such as a keyboard or a mouse. Therefore, the display device including the touch panel becomes widely used.

The touch panel includes a first substrate, a second substrate, a first transparent electrode and a second transparent electrode. The first substrate is spaced apart from the second substrate. The first transparent electrode is formed on the first substrate. The second transparent electrode is formed on the second substrate. The first transparent electrode faces the second transparent electrode.

When the touch panel generates the information on touch, it sequentially reads electrical signals from the area where the first transparent electrode and the second transparent electrode contact with each other.

SUMMARY OF THE INVENTION

Accordingly, the present invention is provided to substantially solve one or more problems due to limitations and disadvantages of the related art.

It is a feature of the present invention to provide a touch panel display device with good sensitivity.

In one exemplary embodiment of the present invention, a liquid crystal display device having a liquid crystal display panel and a backlight assembly is provided. The liquid crystal display panel includes a plurality of touch sensors and a touch sensor controller. Each of the touch sensors is divided into two parts spaced apart from each other and generates an output signal in response to a compression of the liquid crystal display panel. A conductive pad and a conductive column spacer may be used as the two parts of a touch sensor. The distance between the conductive pad and the column spacer is about 0.01 to 0.1 times the distance between the first and second substrates of the liquid crystal display panel. One of the two substrates includes at least two sensing lines substantially perpendicular to each other, and at least one of the two sensing lines is connected to the touch sensors of the liquid crystal display panel. The touch sensor controller defines sensing units. Each of the sensing units includes at least two touch sensors. The touch sensor controller receives the output signal and generates coordinate information of the sensing unit when all of the touch sensors of the sensing unit are generating an output signal or at least one of the touch sensors of the sensing unit is generating an output signal.

In another exemplary embodiment of the present invention, a flat panel display device includes a display panel, and a touch sensor controller. The display panel includes at least two substrates spaced apart and a plurality of touch sensors. Each of the touch sensors generates an output signal containing location information in response to a touch to the first substrate and is disposed between the two substrates. The touch sensor controller defines at least one sensing unit including at least two touch sensors. Each of the touch sensors is divided into two conductive sections disposed on the two substrates separately. One of the two substrates includes at least two sensing lines substantially perpendicular to each other, and at least one of the two sensing lines is connected to a touch sensor. The touch sensor controller receives the output signal and generates coordinate information of the sensing unit when all of the touch sensors of the sensing unit are generating an output signal or at least one of the touch sensors of the sensing unit is generating an output signal.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter the preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1is a schematic cross-sectional view showing a liquid crystal display panel according to a first embodiment of the present invention.

Referring toFIG. 1, a liquid crystal display panel1000includes a color filter substrate100, an array substrate200, a touch sensor310, a liquid crystal layer400and polarizing film500.

The color filter substrate100includes a transparent insulating substrate110, a black matrix layer120, a color filter layer130, a common electrode layer140and a conductive column spacer320. The array substrate200includes a transparent insulating substrate210, a thin film transistor (TFT) layer, and a pixel electrode layer290. A liquid crystal layer400is disposed between the color filter substrate100and the array substrate200. The first polarizing film510and the second polarizing film520are disposed outside the color filter substrate100and the array substrate200separately. A spacer450is disposed between the color filter substrate100and the array substrate200for spacing apart said substrates. Various kinds of spacers can be used for this purpose, such as column spacers and ball spacers.

The touch sensor310is divided into two parts, a conductive column spacer320disposed on the color filter substrate100and a conductive pad330disposed on the array substrate200opposed to the conductive column spacer320. The conductive column spacer320and the conductive pad330are not connected electrically to each other whenever there is no touching of the display panel.

The touch sensor310senses a change in the voltage caused by a change in the distance between the conductive column spacer320and the conductive pad330and sends a signal containing location information to a touch sensor controller via sensing lines. When a touch to the display panel is made, the conductive column spacer320close to the touching point contacts the conductive pad330opposed to the column spacer320because of the pressure made by the touch. And when the touch is removed, the conductive column spacer320is spaced apart from the conductive pad330because of the removal of the pressure made by the touch. So it is possible to determine the point that a touch to the panel is made by sensing the voltage changes between the conductive column spacer320and the conductive pad330.

FIG. 2is a layout showing an array substrate of a liquid crystal display panel according to a first embodiment of the present invention.FIG. 3andFIG. 4are cross-sectional views showing a liquid crystal display panel ofFIG. 2.

Referring toFIG. 2, a liquid crystal display panel according to a first embodiment of the present invention includes a color filter substrate100and an array substrate.

The color filter substrate100includes color filters130including red, green and blue color filters, a black matrix layer and conductive column spacers320. The conductive column spacers320are disposed on every dot defined by three color filters including a red, a green and a blue color filter to form a conductive column spacer array. The number of conductive column spacers320and array method thereof are not limited to the embodiment described herein above. Various kinds of arrangement methods may be used by those skilled in the present art.

The array substrate200disposed opposite of the color filter substrate100includes gate lines220, data lines270, pixel electrodes290and thin film transistors (TFTs). The gate lines220transporting a gate signal are extended in a first direction and the data lines270transporting a data signal are extended in a second direction. The array substrate200further includes first sensing lines351and second sensing lines352. The direction of the first sensing lines351are substantially parallel to the direction of gate lines220and the direction of the second sensing lines352are substantially parallel to the direction of data lines270. Conductive pads330are disposed on each point where first sensing lines351and second sensing lines352meet. Conductive pads330are electrically connected to the two sensing lines and spaced apart from the conductive column spacers320opposed to the conductive pads330.

A touch to the liquid crystal display panel according to the present embodiment causes compression between the area of the color filter substrate100opposed to the touch and the array substrate200opposite the color filter substrate100. A conductive column spacer320disposed on the area of the color filter substrate100contacts a conductive pad330opposite the conductive column spacer320because of the compression caused by the touch. The contact between the conductive column spacer320and the conductive pad330changes the electric resistance and the voltage of the touch sensor including the conductive column spacer320and the conductive pad330. The first sensing line351and the second sensing line352connected to the touch sensor transport changes in the voltage in the sensor to the touch sensor controller600. The touch sensor controller600perceives the changes in voltage and generates coordinates corresponding to the area where the voltage has changed.

The conductive pads330are disposed at the intersection of the first sensing lines351and the second sensing lines352and are isolated from the pixel electrodes290according to this embodiment. The arrangement methods of the conductive pads330are not limited in this embodiment. Various kinds of arrangement methods may be used by those skilled in the present art.

Referring toFIG. 3, a black matrix layer120is disposed on a transparent insulating substrate110. A glass substrate may be used as the transparent insulating substrate110and metallic materials such as chrome or carbonic materials or organic materials may be used to form the black matrix layer120. A plurality of color filters are disposed on the substrate110after forming the black matrix layer. A plurality of bumps321are formed on the black matrix layer120. The bumps may be formed through the following process. First, an organic or inorganic non-conductive layer is deposited on the color filters disposed on the substrate110and then the bumps321are formed by a photolithography process using a mask. A transparent conductive layer is disposed on the color filters130and bumps321to form a common electrode140and conductive column spacers320. Indium-Tin-Oxide (ITO) or Indium-Zinc-Oxide (IZO) may be used as a material for forming the common electrode140and conductive column spacers320. The conductive column spacers320can be formed by the process described above or can be formed by dot printing without photolithography.

Referring toFIG. 4, gate lines220and first sensing lines351are formed on the transparent insulating substrate210. A gate insulating layer240, an amorphous silicon layer250and an amorphous silicon layer doped with impurities260are deposited respectively and form thin film transistors. Data lines270, which include source electrodes271protruding therefrom, drain electrodes273, and second sensing lines352are formed on the substrate210. The passivation layer280is deposited on the substrate210and covers most areas of the substrate including data line270and second sensing lines352. Pixel electrodes290and conductive pads330are disposed on the passivation layer280. The pixel electrodes290contact the drain electrodes273via a contact hole formed in the passivation layer280, and conductive pads330contact the first and the second sensing lines351and352via a contact hole formed in the passivation layer280. The pixel electrodes290and the conductive pads330are formed of transparent conductive materials such as ITO or IZO. The conductive pads330are disposed at the intersection of the first sensing lines351and the second sensing lines352, and are isolated from the pixel electrodes290.

FIG. 5is a block diagram showing a liquid crystal display device according to an embodiment of the present invention.

Referring toFIG. 5, a liquid crystal display device1000includes a touch sensor part300including touch sensors and sensing lines, a touch sensor controller part600and a driving part1200.

The touch sensing part300includes conductive column spacers on the color filter substrate, conductive pads on the array substrate, first sensing lines and second sensing lines. The touch sensors of the touch sensor part300senses the changes of the voltage between the conductive column spacers and the conductive pads opposed to the conductive column spacers. Sensing lines350transport the signals made by the changes of the voltage to the touch sensor controller part600. The touch sensor controller part600receives the signals, senses where the voltage has changed, and generates coordinates of the area where the voltage has changed. The touch sensor controller part600can control the pointer in the screen of the liquid crystal display panel by the coordinates generated. The touch sensor controller part600may be disposed on the liquid crystal panel or a driving circuit separated from the liquid crystal panel.

FIG. 6,FIG. 7AandFIG. 7Bare layouts showing sensing units according to an embodiment of the present invention.

Referring toFIG. 6the touch sensing part300includes first sensing lines351extended in a first direction substantially parallel to the longitudinal direction of the liquid crystal display panel, second sensing lines352extended in a second direction substantially perpendicular to the first direction and touch sensors310. The touch sensors are disposed in array of a m×n matrix and on every dot defined by three pixels including a red, a green and a blue pixel. The number of touch sensors310and array method thereof is not limited to this embodiment described herein above. Various kinds of arrangements and methods may be used by those skilled in the present art.

The touch sensing part300of this embodiment is divided into a plurality of sensing units. Each of the sensing units310uinclude two touch sensor310(x, y) adjacent to each other. The shape of the sensing unit310uis not limited to a particular form. Two touch sensors in a sensing unit may be adjacent to each other in the first direction (310(3,1),310(4,1)) or the second direction (310(1,1),310(1,2)) as shown in the first sensing unit310u1or the second sensing unit310u2. Also two touch sensors in a sensing unit may be adjacent to each other in a diagonal direction (310(1, n),310(2, n−1)), (310(m−1, n−1),310(m, n)) as shown in the third sensing unit310u3or the forth sensing unit310u4. One of the patterns for a sensing unit with two touch sensors described above may be used as a pattern for a sensing unit in the touch sensing part300. Also various kinds of patterns for a sensing unit with two touch sensors including the patterns described above may be used in the touch sensing part300together.

Referring toFIG. 7A and 7B, there are three touch sensors in one sensing unit.FIG. 7Ashows three touch sensors adjacent to each other forming a line andFIG. 7Bshows three touch sensors adjacent to each other have an ‘L’ shape.

The patterns of the sensing unit are not limited to those described above and various kinds of patterns may be used by those skilled in the present art.

FIG. 8Ais a cross-sectional view showing a liquid crystal display panel with touch sensors having high sensitivity.FIG. 8Bis a flow chart illustrating a driving method of a liquid crystal display shown inFIG. 8B.

Referring toFIG. 8A, a liquid crystal display panel includes a color filter substrate100, an array substrate200, a liquid crystal layer disposed between the two substrates, a spacer450and a touch sensor310. The spacer is disposed between the color filter substrate100and the array substrate200for keeping a space between the two substrates. The touch sensor310includes a conductive column spacer320and a conductive pad330opposed to and spaced apart from the conductive column spacer320. When a distance between the conductive pad and the conductive column spacer d2is within 0.01 to 0.1 times the distance between the two substrates d1, the conductive pad330and the conductive column spacer320easily contact each other even under very low pressure. Also the probability of causing a short in sensor310by a small particle is increased because the distance d2is too small.

FIG. 8Billustrates a driving method for successfully decreasing the probability of causing the problems to a liquid crystal display panel described above. A liquid crystal display panel illustrated inFIG. 8Bincludes a touch sensing part including a plurality of touch sensors and a touch sensor controlling part (S810). A plurality of sensing units, each of the units including at least two of the touch sensors, is defined (S820). The touch sensor controller is set up to control each sensing unit when all touch sensors of the unit sense an input signal (S830). When a touch to the liquid crystal display panel is made (S840), the touch sensor controller part decides whether all the touch sensors of the unit opposite the touched position of the liquid crystal display panel sense the input signal made by the touch (S850). If all the touch sensors of the sensing unit sense the input signal, the touch sensor controller part controls the sensing unit (S860). If at least one of the touch sensors of the sensing unit does not sense any signal, the touch sensor controller part does not control the sensing unit (S870).

FIG. 9Ais a cross-sectional view showing a liquid crystal display panel with touch sensors having low sensitivity.FIG. 9Bis a flow chart illustrating a driving method of a liquid crystal display panel showed inFIG. 9B.

Referring toFIG. 9A, the structure of a liquid crystal display panel is the same as the structure of the liquid crystal display panel shown inFIG. 8Aexcept for the distance between the conductive column spacer320and the conductive pad330. The distance between the conductive pad330and the conductive column spacer d3is longer than the distance d2showed shown inFIG. 8A. Thus, the probability for the conductive pad330and the conductive column spacer320to contact each other under low pressure is not high. However, the longer distance d3may cause less sensitivity of the touch sensor310.

FIG. 9Billustrates a driving method for successfully increasing the sensitivity of the liquid crystal display panel shown inFIG. 9Ato a touch. A liquid crystal display panel illustrated inFIG. 9Bincludes a touch sensing part including a plurality of touch sensors and a touch sensor controlling part (S910). A plurality of sensing units, each of the units including at least two of the touch sensors, is defined (S920). The touch sensor controller is set up to control each sensing unit when at least one of the touch sensors of the each unit senses an input signal (S930). When a touch to the liquid crystal display panel is made (S940), the touch sensor controller part decides whether at least one of the touch sensors of the unit opposite the touched position of the liquid crystal display panel senses the input signal made by the touch (S950). If at least one of the touch sensors of the sensing unit senses the input signal, the touch sensor controller part controls the sensing unit (S960). If at least one of the touch sensors of the sensing unit does not sense any signal, the touch sensor controller part does not control the sensing unit (S970).

FIG. 10is a table that compares the probability of causing an electrical fault for a liquid crystal display panel with touch sensors according to the embodiments of the present invention and prior art.

The table inFIG. 10compares liquid crystal display panels having an array of 1368×768 including touch sensors according to the present invention and prior art. Touch sensors are disposed every twelve pixels in each of the liquid crystal display panels. So each panel has 3,151,872 pixels and 262,656 touch sensors. The probability of causing an electrical fault for the liquid crystal display panel according to the prior art is 7.61452E-06 (2/262,656). The probability of causing an electrical fault for a liquid crystal display panel including a plurality of sensing units according to the present invention is 5.7981E-11 ((2/262656)2) if each of the sensing units has two touch sensors and 1.9492E-31 if each of the sensing units has three touch sensors.

FIG. 11is an exploded perspective view showing a liquid crystal display device with touch sensors according to the present invention.

Referring toFIG. 11, a liquid crystal display device2000includes a top frame1300, a liquid crystal display panel1000, driving circuit parts1220,1240and a back light unit including a mold frame1800, optical sheets1700, an optical plate1500, a lamp unit1400and a bottom frame1900. The liquid display panel1000is disposed between the top frame1300and the backlight assembly and includes a color filter substrate100, an array substrate200, a touch sensor part, a liquid crystal layer and polarizing film. The driving circuit parts1220,1240applying a gate and a data signals to the liquid crystal display panel are connected to the liquid crystal display panel and include printed circuit boards (PCB)1224,1244and tape carrier packages (TCP)1222,1242. The lamp unit1400includes a lamp1410and a lamp reflector1411. The optical plate1500and the optical sheets1700are disposed between the bottom frame1900and the liquid crystal display panel1000to change an optical path while guiding the light emitted from the lamp unit toward the liquid crystal display panel to improve the brightness and the uniformity of the light emitted from the lamp unit. A reflective film1600is disposed on the bottom frame1900to reflect the light emitted toward the reflective film. This embodiment shows an edge shaped backlight using a lamp, but various kinds of backlight assemblies may be used. The top frame1300includes first to fourth barrier ribs and is combined with the mold frame1800.

The above-described exemplary methods may be employed to other display devices including, but not limited to organic light emitting diode (OLED) display, plasma display panel (PDP), and the like.

Having described the embodiments of the present invention and its advantages, it is noted that various changes, substitutions and alternations can be made herein without departing from the sprit and scope of the invention as defined by appended claims.