WO2010140770A1

WO2010140770A1 - Input / output device

Info

Publication number: WO2010140770A1
Application number: PCT/KR2010/002553
Authority: WO
Inventors: Dong Hyun Kim
Original assignee: Lg Display Co., Ltd.
Priority date: 2009-06-02
Filing date: 2010-04-23
Publication date: 2010-12-09
Also published as: KR101560408B1; KR20100130057A

Abstract

An input / output device is disclosed, the device characterized by: a light source for generating a light; and a panel for displaying an image by receiving the light and having a touch panel function, where the panel includes a green pixel for converting the light to a green light in a case the touch function is implemented, and a color filter formed with a sensing device for sensing the light reflected in a case the touch function is implemented.

Description

INPUT/OUTPUT DEVICE

The present invention relates to an input/output device, and more particularly to an input/output device configured to have a touch sensor function.

Concomitant with development and popularization of a GUI (graphic user interface), an input-convenient touch screen is widely used these days. Furthermore, in accordance with development of information process technology, display devices such as an LCD, a PDP and an AMOLED are also widely used. Particularly, an optical touch integrated LCD in which an LCD panel is incorporated with an optical sensor is used.

The present invention is disclosed to provide an input/output device configured to have an improved touch sensitivity and to minimize an error caused by noise from outside.

In one general aspect of the present invention, there is provided an input/output device, characterized by: a light source for generating a light; and a panel for displaying an image by receiving the light and having a touch panel function, where the panel includes a green pixel for converting the light to a green light in a case the touch function is implemented, and a color filter formed with a sensing device for sensing the light reflected in a case the touch function is implemented.

In some exemplary embodiments of the present invention, the converted green light may have a wavelength in the range of 500nm to 600nm.

In some exemplary embodiments of the present invention, the sensing device may be configured with amorphous silicon.

In some exemplary embodiments of the present invention, the sensing device may be configured to correspond to the numbers of RGB pixels formed on the color filter.

In some exemplary embodiments of the present invention, the display panel may be characterized by: a gate wiring extended to a first direction; a data wiring crossed at the gate wiring; a pixel electrode facing the color filter; a first switching unit selectively connecting the data wiring and the pixel electrode; a driving unit for receiving an electrical sensing signal formed by converting the green light from the sensing device; and a second switching unit selectively connecting the driving unit and the sensing device.

In some exemplary embodiments of the present invention, the first and secons switching units may be driven by a driving signal applied through the gate wiring.

In another general aspect of the present invention, there is provided an input/output device, characterized by: a panel configured to have a touch panel function; and a light source configured to provide a white light during display of an image and generate a green light during an operation expected region in which the touch function is to be implemented.

In some exemplary embodiments of the present invention, the green light may have a wavelength in the range of 500nm to 600nm.

In some exemplary embodiments of the present invention, the panel may further include a sensing device for sensing a light reflected in a case the touch function is implemented, and the sensing device may be configured with amorphous silicon.

The input/output device according to the present invention is advantageous in that a green light is employed to sense a signal such as a touch input/outputted from outside. At this time, the input/output device may include a sensing device containing amorphous silicon, where the sensing device including the amorphous silicon has an excellent sensitivity relative to the green light. That is, the amorphous silicon has a linear optical absorption coefficient relative to a light of green wavelength. Therefore, the input/output device according to the present invention can have an improved touch sensitivity and easily distinguish the noise from outside because the green light is used and a touch sensing operation is implemented.

FIG. 1 is a cross-sectional view illustrating a cross-section of a liquid crystal display device according to an exemplary embodiment of the present invention.

FIG.2 is a circuit diagram illustrating a green pixel of a liquid crystal display device according to an exemplary embodiment of the present invention. .

FIG.3 is a cross-sectional view of a photo TFT.

FIG.4 is a schematic view illustrating an outside signal-sensing process by a liquid crystal display device according to an exemplary embodiment of the present invention.

FIGS.5 and 6 are waveform diagrams illustrating signals applied to a first line and a second line.

FIG.7 is a schematic view illustrating a liquid crystal display device according to another exemplary embodiment of the present invention.

FIG.8 is a schematic view illustrating a finger position sensing process by a liquid crystal display device according to another exemplary embodiment of the present invention.

FIG.9 is a waveform diagram illustrating signals applied to a first line.

FIG.10 is a circuit diagram illustrating a green pixel according to another exemplary embodiment of the present invention.

FIG.11 is a block diagram illustrating a driving method of a liquid crystal display device according to the present invention.

FIG.12 is a graph illustrating an optical absorption coefficient of amorphous silicon.

Hereinafter, embodiments of the present invention are described in detail with reference to the accompanying drawings. Detailed descriptions of well-known functions, configurations or constructions are omitted for brevity and clarity so as not to obscure the description of the present invention with unnecessary detail. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

It will be understood that when an element (each substrate, device, member, electrode, pattern or layer) is referred to as being "on" or "under" another element, it means that the element can be directly connected or coupled to the other element or intervening elements may be present. Phases of each element or the following refereneces are explained based on the given figures. In the drawings, the size or relative sizes of elements in the drawings may be exaggerated for clarity and do not constitute the actual sizes. Like reference numerals refer to like elements throughout the specification.

FIG. 1 is a cross-sectional view illustrating a cross-section of a liquid crystal display device according to an exemplary embodiment of the present invention, FIG.2 is a circuit diagram illustrating a green pixel of a liquid crystal display device according to an exemplary embodiment of the present invention, FIG.3 is a cross-sectional view of a photo TFT, FIG.4 is a schematic view illustrating an outside signal-sensing process by a liquid crystal display device according to an exemplary embodiment of the present invention and FIGS.5 and 6 are waveform diagrams illustrating signals applied to a first line and a second line.

Referring to FIGS. 1 through 6, a liquid crystal display device may include a backlight unit (10) and a liquid crystal panel (20).

The backlight unit (10) generates light and emits the light toward the crystal liquid panel (20). For example, the backlight unit (10) may generate white light and emits the white light evenly to a rear surface of the liquid crystal panel (20). The backlight unit (10) may include a lightguide plate formed under the liquid crystal panel (20), a light emitting diode (11) generating light and emits the light to a lateral surface of the lightguide plate, and an optical sheet interposed between the light emitting diode (11) and the liquid crystal panel (20).

Furthermore, the backlight unit (10) may include a reflective sheet and the lightguide plate formed under the lightguide plate, the light emitting diode (11), and a frame accommodating the optical sheet and reflective sheet.

The liquid crystal panel (20) may receive the light emitted by the backlight unit (10) and display an image thereon. To be more specific, the liquid crystal panel (20) may receive the light generated by the light emitting diode (11), adjust the intensity of light transmissive for each pixel unit and display an image thereon.

As shown in FIG.1, the liquid crystal panel (20) may include an upper substrate (100), a bottom substrate (200) and a liquid crystal layer (300). The upper substrate (100) is formed opposite to the bottom substrate (200).The upper substrate (100) may include a first transparent substrate (110), a color filter layer (120) and a common electrode layer (130).

The transparent substrate (110) is a transparent insulating substrate. The transparent substrate (110) may be, for instance, a glass substrate, a plastic substrate or a quartz substrate. The first transparent substrate (110) supports the color filter layer (120) and the common electrode layer (130). The color filter layer (120) may filter the light passing through the liquid crystal layer (300) and converts the filtered light to a colored light. The color filter layer (120) may include a black matrix pattern (121) blocking the passing light, a red color filter (122), a green color filter (123) and a blue color filter (124).

The red color filter (122) may filter the passing white light and convert the filtered light to red light. The green color filter (123) may filter the passing white light and convert the filtered light to green light. For example, the green color filter (123) may filter the passing white light and convert the filtered light to a light having a wavelength in the range of approximately 500nm to 600nm. The blue color filter (124) may filter the passing white light and convert the filtered light to blue light.

The common electrode layer (130) may be formed under the color filter layer (120). The common electrode layer (130) may include a common electrode applying an electromagnetic field to the liquid crystal layer (300). The bottom substrate (200) is formed opposite to the upper substrate (100). The bottom substrate (200) may include a second transparent substrate (210) and a TFT (thin film transistor) layer (220).

The second transparent substrate (210) is a transparent insulating substrate. The second transparent substrate (210) may be, for instance, a glass substrate, a plastic substrate or a quartz substrate. The second transparent substrate (210) supports the transparent substrate (210) and the TFT layer (220).

The TFT layer (220) may be formed on the second transparent substrate (210). The TFT layer (220) may apply an electromagnetic field to the liquid crystal layer (300). The TFT layer (220) may include a plurality of wirings, a plurality of switching elements, a plurality of electrodes and a plurality of sensing devices (230). The TFT layer (220) may include a plurality of gate wirings (221) extended to one direction, and a plurality of data wirings (222) crossed with the gate wirings (221) to be extended to a second direction.

At this time, a plurality of pixels are defined by the gate wirings (221) and the data wirings (222). The pixels may be divided into a red pixel (PX1), a green pixel (PX2) and a blue pixel (PX3) by the color filters (122, 123, 124). That is, the red pixel (PX1) may display a red image in opposition to the red color filter (122). The green pixel (PX2) may display a green image in opposition to the green color filter (123). The blue pixel (PX3) may display a blue image in opposition to the blue color filter (124).

The TFT layer (220) may include a first TFT (223) arranged at a region on which the gate wirings (221) and the data wirings (222) are crossed, and a pixel electrode (224) arranged on each pixel and selectively connected to the data wirings (222) by the first TFT ((223). That is, the first TFT (223) is a switching element selectively connecting the pixel electrode (224) and the data wirings (222). The pixel electrode (224) forms an electromagnetic field in response to a data signal applied through the data wirings (222), and the electromagnetic field formed between the common electrode and the pixel electrode (224) changes the optical characteristics of the liquid crystal layer (300).

As illustrated in FIGS. 1 and 2, the TFT layer (220) may include a sensing element (230), a lead-out wiring (226), first/second driving voltage wirings (227, 228) and a second TFT (229) arranged on the green pixel (PX2).

The sensing element (230) is formed opposite to the green color filter (123). The sensing element (230) may be so arranged as to correspond to a through hole (125) formed at the green color filter (123). The sensing element (230) senses the light incident from the outside.

Referring to FIG.3, the sensing element (230) may be a photo TFT (230) sensing the light incident from the outside, for example. The photo TFT (230) may include a gate electrode (231), a gate insulating film (232), an active layer (233), a source electrode (234), a drain electrode (235) and a protective film (237).

The gate electrode (231) is arranged on the second transparent substrate (210) and connected to the second driving voltage wiring (228). The gate insulating film (232) covers the gate electrode (231) to insulate the gate insulating film (232) and the active layer (233). The gate insulating film (232) covers the gate wiring (221). The active layer (233) is arranged on the gate insulating film (232). That is, the active layer (233) may receive an outside light to adjust the intensity of a current flowing between the source electrode (234) and the drain electrode (235) in response to the intensity of the outside light.

The active layer (233) may include an amorphous silicon. To be more specific, the active layer (233) is comprised of amorphous silicon. The source electrode (234) and the drain electrode (235) are connected to the active layer (233), where the source electrode (234) and the drain electrode (235) are discretely arranged. To be more specific, the source electrode (234) and the drain electrode (235) are connected to the active layer (233) through an ohmic contact layer (236).

The source electrode (234) is connected to the first driving voltage wiring (227) and the drain electrode (235) is connected to the second TFT (229). The protective film (237) covers the source electrode (234) and the drain electrode (235).

The photo TFT (230) senses the light incident from outside. That is, the photo TFT (230) adjusts the intensity of current flowing between the source electrode (234) and the drain electrode (235) responsive to the intensity of light input/outputted from the outside. As a result, the intensity of light input/outputted from the photo TFT (230) may be measured through the intensity of current flowing in the photo TFT (230). A photo diode including the amorphous silicon and the photo TFT (230) may be used for the sensing diode (230).

The lead-out wiring (226) transmits to a driving unit the electrical signal formed by converting the intensity of light, i.e., the intensity of current sensed by the photo TFT (230). The driving unit reads out the input/outputted electrical signal to determine a position on which a signal such as the touch is input/outputted.

The first and second driving voltage wirings (227, 228) apply a driving voltage to the photo TFT (230). As mentioned in the foregoing, the first driving voltage wiring (227) is connected to the source electrode (234) while the second driving voltage wiring (228) is connnected to the gate electrode (231).

The second TFT (229) selectively transmits the electrical signal sensed by the photo TFT (230) to the lead-out wiring (226). That is, the second TFT (229) selectively connects the photo TFT (230) and the lead-out wiring (226). To be more specific, the second TFT (229) is a switching unit selectively connecting the photo TFT (230) and the lead-out wiring (226). Furthermore, the second TFT (229) is connected to the gate wiring (221) to be driven by a signal applied through the gate wiring (221).

Unlike what is shown in FIG.2, the second TFT (229) may be driven by a driving signal applied through the gate wiring (221) and another wiring. The TFT layer (220) may further include a first storage capacitor (Cst1) temporarily storing a data signal applied to the pixel electrode (224) and a second storage capacitor (Cst2) temporarily storing a signal generated by the photo TFT (230). The liquid crystal layer (300) is interposed between the upper substrate (100) and the bottom substrate (200). The liquid crystal layer (300) is driven by an electromagnetic field formed between the pixel electrode (224) and the common electrode.

The upper substrate (100) and the bottom substrate (200) may further include an alignment layer that is adjacent to the liquid crystal layer (300). Furthermore, the liquid crystal panel (20) may include a polarization sheet that is aligned under the bottom substrate (200) and on the upper substrate (100).

A liquid crystal display device according to the exemplary embodiment of the present invention uses the green light to sense a signal such as a touch as shown in FIG.4.

Now, referring to FIG.5, an image is displayed on the gate wiring of a first line, and a first gate signal (GS1) for emitting light for sensing an outside touch is applied. The first gate signal (GS1) may include a first period (PD1) for displaying an image, and a second period (PD2) for emitting green light.

During the first period (PD1), signals (DS1, DS2, DS3....) for displaying image on the entire data wiring (222) is applied, while during the second period (PD2), a predetermined signal (DS2) is applied only to the data wiring corresponding to the green pixel (PX2).

Likewise, as shown in FIG.6, an image is displayed to the gate wiring of second line and a second signal (GS2) for emitting light for sensing the outside touch is applied. The second gate signal (GS2) may include a third period (PD3) for displaying an image and a fourth period (PD4) for emitting the green light.

During the third period (PD3), signals (DS1, DS2, DS3....) for displaying image on the entire data wiring (222) is applied, while during the fourth period (PD4), a predetermined signal (DS2) is applied only to the data wiring corresponding to the green pixel (PX2).

In the same manner, gate signals are applied to the entire line of the gate wirings (221), whereby a green light of apredetermined size and wavelength is emitted through the green pixel (PX2) during the second period (PD2) and the fourth period (PD4), and part of the emitted green light is reflected by fingers and incident again.

Each length of the second period (PD2) and the fourth period (PD4) may be less than approximately 1ms. At this time, the green light is sensed by the sensing diode (230), and a position such as a finger is input/outputted by the sensing diode (230) and the driving unit. Because the sensing diode (230) includes amorphous silicon, the sensing diode (230) generates electrical signals of mutually different sizes in response to the green light incident by being reflected by the finger and the green light incident from the outside.

At this time, the amorphouse silicon has a linear optical absorption coefficient relative to light of green wavelength, whereby the sensing diode (230) generates an electrical signal whose intensity is linearly changed responsive to a difference of wavelength in the green light. Therefore, the driving unit can easily determine the electrical signal input/outputted from the sensing diode (230), whereby the position of a finger can be easily determined. Therefore, the liquid crystal display device according to the exemplary embodiment is an input/output device capable of minimizing an error caused by the outside noise with an improved touch sensitivity.

FIG.7 is a schematic view illustrating a liquid crystal display device according to another exemplary embodiment of the present invention, FIG.8 is a schematic view illustrating a finger position sensing process by a liquid crystal display device according to another exemplary embodiment of the present invention, and FIG.9 is a waveform diagram illustrating signals applied to a first line.

In another exemplary embodiment of the present invention, a backlight unit and a color filter layer will be additionally described with reference to the first embodiment. The explanation of the present embodiment may be basically coupled to that of the first embodiment.

Referring to FIGS. 7 through 9, a backlight unit (30) includes a red light source (31), a green light source (32) and a blue light source (33). For example, the backlight unit (30) may include a red light emitting diode (31), a green light emitting diode (32) and a blue light emitting diode (33).

The backlight unit (30) sequentially emits red light, green light and blue light to the liquid crystal panel (40). More particularly, the backlight unit (30) uniformly emits the red light generated by the red light source (31) to a rear surface of the liquid crystal panel (40), and then uniformly emits the green light generated by the green light source (32) to the rear surface of the liquid crystal panel (40). Successively, the blue light generated by the blue light source (33) is uniformly emitted to the rear surface of the liquid crystal panel (40).

The liquid crystal panel (40) does not include a color filter. That is, the liquid crystal panel (40) uses the red light, the green light and the blue light to display an image having the colors.

As illustrated in FIG.8, the liquid crystal display device according to the present exemplary embodiment uses the green light to sense a signal such as touch, that is, a position of a finger.

Referring to FIG.9, a liquid crystal display device according to the present exemplary embodiment sequentially turns on the red light source (31), the green light source (32) and the blue light source (33) to display an image, whereby the green light source (32) is turned on again to generate a green light for sensing the position of the finger.

At this time, the green light source (32) emits a green light for sensing the signal such as touch for a very short period of time, for example, approximately 10 s to 16 s. The green light emitted by the green light source (32) is reflected by the finger, and a sensing diode (430) included in the liquid crystal panel (40) senses the light reflected by the finger. The sensing diode (430) includes the amorphous silicon, such that a avelength of green light emitted by the green light source (32) and a wavelength of green light input/outputted from outside can be easily distinguished. Therefore, the liquid crystal display device according to the present exemplary embodiment is an input/output device capable of minimizing the error caused by the outside noise with improved touch sensitivity.

FIG.10 is a circuit diagram illustrating a green pixel according to another exemplary embodiment of the present invention. The previously explained embodiment may be fundamentally incorporated with the present exemplary embodiment.

Referring to FIG.10, a TFT layer includes a third storage capacity (Cst3) and a third driving voltage wiring (Vdd). The third storage capacitor (Cst3) is connected to a pixel electrode (224) to store charge for driving the photo TFT. In addition, tfhe third storage capacitor (Cst3) is connected to a gate of the photo TFT.

The third driving voltage wiring (Vdd) is arranged in parallel with the data wiring (m). The third driving voltage wiring (Vdd) supplies a driving voltage to a source of the photo TFT.

A difference of photo leakage current generated by the photo TFT occurs in response to the intensity of light irradiated to the photo TFT. That is, the intensity of light leakage current of the photo TFT touched by the finger may be greater than or smaller than the intensity of light leakage current of another photo TFT.

As noted above, the second storage capacity (Cst2) is stored with charge based on the light leakage current generated by the photo TFT. The charge stored in the second storage capacity (Cst2) is transmitted to a driving unit in an analog signal through a lead-out wiring (RO) responsive to the operation of the second TFT. At this time, the driving unit converts the analog signal transmitted through the lead-out wiring (RO) to a digital signal.

The driving unit calculates the touched position in a coordinate based on the digital signal. As noted above, the liquid crystal display device according to another exemplary embodiment can sense the touch signal input/outputted by the method in which the charge is stored in the storage capacitor.

FIG.11 is a block diagram illustrating a driving method of a liquid crystal display device according to the present invention. FIG.12 is a graph illustrating an optical absorption coefficient of amorphous silicon.

As can be noted from the illustrated graph, the optical absorption coefficient of amorphous silicon has a linear characteristic at a B region. Therefore, if the touch function of touch panel is utilized by making good use of the region, it can be more reliably implemented. B region corresponds to a light of green series. Therefore, in a case the touch function is implemented while the green light is provided, an input/output sensitivity can be further enhanced.

The present invention exemplifies two methods of providing green light. First, only G pixels in the RGB pixels are operated while the touch function is implemented. Because only G pixels are operated while the touch function is implemented, such that a same effect as that of the panel being provided with green light can be expected. The light reflected from the touch may be absorbed by a sensing diode so installed as to correspond to the pixel. At this time, the green light may have the wavelength in the range of 500nm to 600nm. The sensing diode includes the amorphous silicon.

Furthermore, as illustrated in FIG.11, in performing the touch function, instead of providing the green light to the entire region of the panel at one time, the green light may be provided per line. In a case the green light is provided to an entire region of the panel at one time, a user can recognize the green light even if the panel is provided with an image at a fast speed. To cope with this, if the green light is provided per line, there is no possibility that user can recognize the green light. Furthermore, the present embodiment can be applied to where the panel is operated by a dot inversion and a frame inversion in addition to the line inversion operation.

Secondly, the backlight unit is so configured as to allow the white light and green light to be selectively provided to the panel, and the green light is provided to the panel while the touch function is being implemented.

The light reflected from the touch may be absorbed by a sensing diode so installed as to correspond to the pixel. At this time, the green light may have the wavelength in the range of 500nm to 600nm. The sensing diode may include the amorphous silicon. The sensing diode may be arranged in numbers corresponding to those of RGB pixels provided at the color filter.

While the present disclosure has been particularly shown and described with reference to exemplary embodiments thereof, the general inventive concept is not limited to the above-described embodiments. It will be understood by those of ordinary skill in the art that various changes and variations in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.

The input/output device according to the present invention has an industrial applicability in that a green light is employed to sense a signal such as a touch input/outputted from outside, at this time, the input/output device includes a sensing device containing amorphous silicon, where the sensing device including the amorphous silicon has an excellent sensitivity relative to the green light. That is, the amorphous silicon has a linear optical absorption coefficient relative to a light of green wavelength. Therefore, the input/output device according to the present invention can have an improved touch sensitivity and easily distinguish the noise from outside because the green light is used and a touch sensing operation is implemented.

Claims

An input/output device, characterized by: a light source for generating a light; and a panel for displaying an image by receiving the light and having a touch panel function, where the panel includes a green pixel for converting the light to a green light in a case the touch function is implemented, and a color filter formed with a sensing device for sensing the light reflected in a case the touch function is implemented.
The device of claim 1, characterized in that the converted green light has a wavelength in the range of 500nm to 600nm.
The device of claim 1, characterized in that the sensing device is configured with amorphous silicon.
The device of claim 1, characterized in that the sensing device is configured to correspond to the numbers of RGB pixels formed on the color filter.
The device of claim 1, characterized in that the display panel is characterized by: a gate wiring extended to a first direction; a data wiring crossed at the gate wiring; a pixel electrode facing the color filter; a first switching unit selectively connecting the data wiring and the pixel electrode; a driving unit for receiving an electrical sensing signal formed by converting the green light from the sensing device; and a second switching unit selectively connecting the driving unit and the sensing device.
The device of claim 5, characterized in that the first and secons switching units are driven by a driving signal applied through the gate wiring.
An input/output device, characterized by: a panel configured to have a touch panel function; and a light source configured to provide a white light during display of an image and generate a green light during an operation expected region in which the touch function is to be implemented.
The device of claim 7, characterized in that the green light has a wavelength in the range of 500nm to 600nm.
The device of claim 7, characterized in that the panel further includes a sensing device for sensing a light reflected in a case the touch function is implemented, and the sensing device may be configured with amorphous silicon.
The device of claim 9, characterized in that the sensing device is configured to correspond to the numbers of RGB pixels formed on the color filter.