Patent Publication Number: US-2007109472-A1

Title: Thin film transistor array, transflective thin film transistor liquid crystal display, LCD device and electronic device

Description:
BACKGROUND OF THE INVENTION  
      1. Field of Invention  
      The present invention relates to a thin film transistor array (TFT array). More particularly, the present invention relates to a transflective thin film transistor liquid crystal display (TFT-LCD) with high aperture ratio.  
      2. Description of Related Art  
      To match the life style of modern people, video or imaging equipment is becoming lighter and slimmer. Although the conventional cathode ray tube (CRT) has many advantages, the design of the electron gun renders it heavy and bulky. Moreover, there is always some danger of hurting viewer&#39;s eyes due to the production of a little radiation. With big leaps in the techniques in manufacturing semiconductor devices and opto-electronic devices, flat panel displays such as liquid crystal displays (LCD), organic light-emitting displays (OLED) and plasma display panels (PDP) has gradually become the mainstream display products.  
      Depending on the light source, a liquid crystal display can be classified as three types: the reflective LCD, the transmissive LCD and the transflective LCD. Taking a transflective LCD as an example, the transflective LCD mainly includes a liquid crystal panel and a back light module. The transflective LCD panel includes two transparent substrates and a liquid crystal layer sandwiched therebetween. The back light module provides a surface light source to illuminate the liquid crystal panel for displaying some images. More specifically, the transflective LCD panel includes a plurality of pixels each having a transmissive region and a reflective region respectively, wherein the transmissive region and the reflective region have different cell-gaps.  
       FIG. 1  is a schematic top view of a conventional transflective LCD panel;  FIG. 2  is schematic sectional view taken along line A-A of the conventional transflective LCD panel in  FIG. 1 . Referring  FIG. 1  and  FIG. 2 , the conventional transflective LCD panel  100  includes a thin film transistor array  110 , a color filter  120  and a liquid crystal layer  130 . The color filter  120  is disposed above the thin film transistor array  110 , and the liquid crystal layer  130  is sandwiched between the thin film transistor array  110  and the color filter  120 .  
      Referring  FIG. 1  and  FIG. 2 , in the conventional thin film transistor array  110 , a plurality of transflective pixels P are defined thereon. Each transflective pixel P includes a transmissive region T and a reflective region R. Since a protrusion layer  122  is formed on a surface of the color filter  120 , a cell-gap G/2 is formed between the reflective region R of the transflective pixel P and the color filter  120 , while a cell-gap G is formed between the transmissive region T of the transflective pixel P and the color filter  120 .  
      As shown in  FIG. 1  and  FIG. 2 , in the same column of the thin film transistor array  110 , since the reflective region R and the transmissive region T of the pixels P are arranged alternatively, reverse tilt domains D 1 , D 2  are not only generated at an area within the pixel P, but also generated at the edge of each pixel P. More specifically, since thickness-transition areas are formed at the edge of the protrusion layer  122 , the reverse tilt domains D 1 , D 2  are generated at the edge of each pixel P and the area within the pixel P that is corresponding to an area between the transmissive region T and the reflective region R of the thin film transistor array  110 . Therefore, aperture ratio of the conventional transflective LCD panel  100  is limited by the reverse tilt domains D 1  that are generated at the edge of each pixel P. For high definition LCD panels having high aperture ratio, reverse tilt domains must be reduced.  
     SUMMARY OF THE INVENTION  
      The present invention provides a transflective thin film transistor liquid crystal display with high aperture ratio, by structuring the transmissive regions of adjacent pixels to be adjacent. In one embodiment of the present invention, the adjacent transmissive regions are contiguous.  
      As embodied and broadly described herein, the present invention provides a thin film transistor array substrate including a substrate, a first pixel groups and a second pixel groups disposed on the substrate and arranged along a first direction. The first pixel group has a first reflective region and a first transmissive region, the second pixel group has a second transmissive region and a second region, which are arranged along a second direction, wherein the first direction is perpendicular to the second direction and the first transmissive region is contiguous to the second transmissive region.  
      As embodied and broadly described herein, the invention provides a transflective thin film transistor liquid crystal display includes the thin film transistor array substrate mentioned above, a color filter substrate disposed above the thin film transistor array substrate, and a liquid crystal layer located between the color filter substrate and the thin film transistor array substrate.  
      As embodied and broadly described herein, the invention provides a liquid crystal display device comprising the transflective thin film transistor liquid crystal display mentioned above.  
      As embodied and broadly described herein, the invention provides an electronic device comprising the transflective thin film transistor liquid crystal display mentioned above.  
      One or part or all of these and other features and advantages of the present invention will become readily apparent to those skilled in this art from the following description wherein there is shown and described a preferred embodiment of this invention, simply by way of illustration of one of the modes best suited to carry out the invention. As it will be realized, the invention is capable of different embodiments, and its several details are capable of modifications in various, obvious aspects all without departing from the invention. Accordingly, the drawings and descriptions will be regarded as illustrative in nature and not as restrictive. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The accompanying drawings are included to provide a further understanding of the present invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.  
       FIG. 1  is a schematic top view of a conventional transflective LCD panel.  
       FIG. 2  is schematic sectional view taken along line A-A of the conventional transflective LCD panel in  FIG. 1 .  
       FIG. 3  is a schematic top view of a transflective LCD panel according to one embodiment of the present invention.  
       FIG. 4  is a schematic sectional view taken along line B-B of the transflective LCD panel in  FIG. 3  according to one embodiment of the present invention.  
       FIG. 5  is a schematic top view of another transflective LCD panel according to one embodiment of the present invention.  
       FIG. 6  is a schematic sectional view taken along line C-C of another transflective LCD panel in  FIG. 5  according to one embodiment of the present invention.  
       FIG. 7  is a schematic view of an LCD device according to one embodiment of the present invention.  
       FIG. 8  is a schematic view of an electronic device according to one embodiment of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       FIG. 3  is a schematic top view of a transflective LCD panel according to one embodiment of the present invention;  FIG. 4  is a schematic sectional view taken along line B-B of the transflective LCD panel in  FIG. 3  according to one embodiment of the present invention. Referring to  FIG. 3  and  FIG. 4 , the transflective LCD panel  200  of the present invention includes a thin film transistor array substrate  210 , a color filter substrate  220  and a liquid crystal layer  230 . The color filter substrate  220  is disposed above the thin film transistor array substrate  210 , and the liquid crystal layer  230  is sandwiched between the thin film transistor array substrate  210  and the color filter substrate  220 .  
      Referring to  FIG. 3  and  FIG. 4 , in this illustrated embodiment of the present invention, the thin film transistor array substrate  210  includes a substrate  212 , a plurality of scan lines  214  disposed on the substrate  212 , a plurality of data lines  216  disposed on the substrate  212 , a first pixel groups  218   a  disposed on the substrate  212  and a second pixel groups  218   b  disposed on the substrate  212 . The arrangement of the scan lines  214 , the data lines  216 , the first pixel groups  218   a  and the second pixel groups  218   b  is well-known to skilled artisans, therefore further elaboration is not required for an understanding of the present invention. The first pixel group  218   a  has a first reflective region R 1  and a first transmissive region T 1 . The second pixel group  218   b  has a second transmissive region T 2  and a second reflective region R 2 . The first pixel groups  218   a  and the second pixel groups  218   b  are controlled by the scan lines  214  and the data lines  216  and arranged alternatively along a column direction. As shown in  FIG. 3  and  FIG. 4 , in the thin film transistor array substrate  210 , a sequence of the first reflective regions R 1 , the first transmissive regions T 1 , the second transmissive regions T 2  and the second reflective regions R 2  is arranged along the column direction.  
      As shown in  FIG. 3  and  FIG. 4 , the first pixel group  218   a  includes a plurality of first pixels P 1  arranged along the row direction, and each first pixel P 1  includes a first thin film transistor  219   a  electrically connected to one of the scan lines  214  and one of the data lines  216 , a first reflective electrode  219   b  electrically connected to the first thin film transistor  219   a , and a first transmissive electrode  219   c  electrically connected to the first reflective electrode  219   b , wherein the first reflective electrode  219   b  and first transmissive electrode  219   c  are arranged along the column direction.  
      As shown in  FIG. 3  and  FIG. 4 , the second pixel group  218   b  includes a plurality of second pixels P 2  arranged along the row direction, and each second pixel P 2  includes a second thin film transistor  219   d  electrically connected to one of the scan lines  214  and one of the data lines  216 , a second transmissive electrode  219   e  electrically connected to the second thin film transistor  219   d , and a second reflective electrode  219   f  electrically connected to the second transmissive electrode  219   e , wherein the second transmissive electrode  219   e  and second reflective electrode  219   f  are arranged along the column direction.  
      As shown in  FIG. 3  and  FIG. 4 , the color filter substrate  220  includes a second substrate  222 , a plurality of color filter films  223  disposed on the second substrate  222 , a protrusion layer  224  disposed on the substrate  222  and a common electrode  226  disposed over the second substrate  222 . The protrusion layer  224  that comprises a plurality of protrusions is located above the first reflective region R 1  and the second reflective region R 2 . Each protrusion narrows the spacing between the color filter substrate  220  and the thin film transistor array substrate  210 . According to various embodiments, a thickness of the spacing located above the first reflective region R 1  and the second reflective region R 2  can be equal to half thickness of the spacing located above the first transmissive region T 1  and the second transmissive region T 2 . The common electrode  226  covers the color filter films  223  and the protrusion layer  224 .  
      In the same column of the thin film transistor array substrate  210 , since the first transmissive region T 1  of the first pixels P 1  and the second transmissive region T 2  of the second pixels P 2  are arranged contiguous only reverse tilt domains D 2  are generated at an area within the first pixel P 1  and the second pixel P 2 . Therefore, aperture ratio of the transflective LCD panel  200  can be further enhanced because the reverse tilt domains D 1  are eliminated at the edge of each first pixel P 1  and the second pixel P 2 , as compared to D 1  in  FIG. 2 .  
       FIG. 5  is a schematic top view of another transflective LCD panel according to one embodiment of the present invention;  FIG. 6  is a schematic sectional view taken along line C-C of another transflective LCD panel in  FIG. 5  according to one embodiment of the present invention. Referring to  FIG. 5  and  FIG. 6 , the transflective LCD panel  300  of the present invention includes a thin film transistor array substrate  310 , a color filter substrate  320  and a liquid crystal layer  330 . The color filter substrate  320  is disposed above the thin film transistor array substrate  310 , and the liquid crystal layer  330  is sandwiched between the thin film transistor array substrate  310  and the color filter substrate  320 .  
      Referring  FIG. 5  and  FIG. 6 , in the present invention, the thin film transistor array substrate  310  includes a substrate  312 , a plurality of scan lines  314  disposed on the substrate  312 , a plurality of data lines  316  disposed on the substrate  312 , and a first pixel groups  318   a  disposed on the substrate  312 . The first pixel group  318   a  has a first reflective region R 1  and a first transmissive region T 1 , and a second pixel groups  318   b  disposed on the substrate  312 , the second pixel group  318   b  has a second transmissive region T 2  and a second reflective region R 2 . The arrangement of the scan lines  314 , the data lines  316 , the first pixel groups  318   a  and the second pixel groups  318   b  is well-known to skilled artisans, therefore detail description is omitted. The first pixel groups  318   a  and the second pixel groups  318   b  are controlled by the scan lines  314  and the data lines  316  and arranged alternatively along the row direction. As shown in  FIG. 5  and  FIG. 6 , in the thin film transistor array substrate  310 , a sequence of the first reflective regions R 1 , the first transmissive regions T 1 , the second transmissive regions T 2  and the second reflective regions R 2  is arranged along the row direction.  
      As shown in  FIG. 5  and  FIG. 6 , the first pixel group  318   a  includes a plurality of third pixels P 3  arranged along the column direction, and the third pixel P 3  includes a third thin film transistor  319   a  electrically connected to one of the scan lines  314  and one of the data lines  316 , a third reflective electrode  319   b  electrically connected to the third thin film transistor  319   a  and a third transmissive electrode  319   c  electrically connected to the third reflective electrode  319   b , wherein the third reflective electrode  319   b  and third transmissive electrode  319   c  are arranged along the row direction.  
      As shown in  FIG. 5  and  FIG. 6 , each second pixel group  318   b  includes a plurality of fourth pixels P 4  arranged along the column direction, and each fourth pixel P 4  includes a fourth thin film transistor  319   d  electrically connected to one of the scan lines  314  and one of the data lines  316 , a fourth transmissive electrode  319   e  electrically connected to the fourth thin film transistor  319   d , and a fourth reflective electrode  319   f  electrically connected to the fourth transmissive electrode  319   e , wherein the fourth transmissive electrode  319   e  and fourth reflective electrode  319   f  are arranged along the row direction.  
      As shown in  FIG. 5  and  FIG. 6 , the color filter substrate  320  includes a second substrate  322 , a plurality of color filter films  323  disposed on the second substrate  322 , a protrusion layer  324  disposed on the substrate  322 , and a common electrode  326  disposed over the second substrate  322 . The protrusion layer  324  is located above the first reflective region R 1  and the second reflective region R 2 . The common electrode  326  covers the color filter films  323  and the protrusion layer  324 .  
      In the same group of the thin film transistor array substrate  310 , since the first transmissive region T 1  of the third pixels P 3  and the second transmissive region T 2  of the fourth pixels P 4  are arranged together, only reverse tilt domains D 2  are generated at an area within the third pixel P 3  and the fourth pixel P 4 . Therefore, aperture ratio of the transflective LCD panel  300  can be further enhanced because the reverse tilt domains D 1  are eliminated at the edge of each third pixel P 3  and the fourth pixel P 4 .  
       FIG. 7  is a schematic view of an LCD device (e.g., a display monitor) according to one embodiment of the present invention. Referring to  FIG. 7 , an LCD device  400  including the transflective LCD panel  200  or  300  is provided. For example, the LCD device  400  of the present invention comprises the transflective LCD panel  200  or  300  mentioned above, a back light unit  410 , a frame  420 , a bezel  430  and an image controller  440 . The transflective LCD panel  200  or  300  and the back light unit  410  are carried by the frame  420 . The transflective LCD panel  200  or  300 , the back light unit  410  and the frame  420  are fastened by the bezel  430 . In addition, the image controller  440  is electrically coupled with the transflective LCD panel  200  or  300  and the back light unit  410  by appropriate manners.  
       FIG. 8  is a schematic view of an electronic device (e.g., a notebook computer, personal digital assistant, digital camera, etc.) according to one embodiment of the present invention. Referring to  FIG. 8 , an electronic device  500  including the transflective LCD panel  200  or  300  is provided. For example, the electronic device  500  of the present invention comprises the transflective LCD panel  200  or  300  mentioned above, a back light unit  510 , a frame  520 , a bezel  530 , an image controller  540  and a system controller  550  implementing the control functions for the particular electronic device. The system controller may include components such as a data source, a data interface, etc. The transflective LCD panel  200  or  300  and the back light unit  510  are carried by the frame  520 . The transflective LCD panel  200  or  300 , the back light unit  510  and the frame  520  are fastened by the bezel  530 . In addition, the image controller  540  and the system controller  550  are electrically coupled with the transflective LCD panel  200  or  300  and the back light unit  510  directly or in directly by appropriate manners.  
      The foregoing description of the preferred embodiment of the present invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form or to exemplary embodiments disclosed. Accordingly, the foregoing description should be regarded as illustrative rather than restrictive. Obviously, many modifications and variations will be apparent to practitioners skilled in this art. The embodiments are chosen and described in order to best explain the principles of the invention and its best mode practical application, thereby to enable persons skilled in the art to understand the invention for various embodiments and with various modifications as are suited to the particular use or implementation contemplated. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents in which all terms are meant in their broadest reasonable sense unless otherwise indicated. It should be appreciated that variations may be made in the embodiments described by persons skilled in the art without departing from the scope of the present invention as defined by the following claims. Moreover, no element and component in the present disclosure is intended to be dedicated to the public regardless of whether the element or component is explicitly recited in the following claims.