Patent Publication Number: US-2021191193-A1

Title: Liquid crystal display device

Description:
FIELD OF INVENTION 
     The present disclosure relates to a liquid crystal display device, and more particularly to a liquid crystal display device in which a sensor is disposed in a visible area of a liquid crystal panel. 
     BACKGROUND OF INVENTION 
     Liquid crystal display devices generally refer to various devices which use liquid crystal panels, such as displays and various mobile devices, wherein mobile phones are the most representative mobile devices. 
     With continuous improvement of manufacturing process of mobile phones, mobile phone screens of the mobile phone tends toward larger sizes and larger screen-to-body ratio. The screen-to-body ratio is used to indicate a ratio of the area of the mobile phone screen and the front panel of the mobile phone, and the current screen-to-body ratio of the mobile phone has gradually increased from 80% to more than 90%. 
     However, in order to further improve the screen-to-body ratio of the mobile phone, in the prior art, the front sensor portion of the mobile phone is included in a visible area of the mobile phone screen, that is, the screen-to-body ratio is increased by digging a hole in the mobile phone screen, thereby improve the overall aesthetic design of the mobile phone. 
     Referring to  FIG. 1 , which is a schematic partial cross-sectional view of a conventional liquid crystal display device. A conventional liquid crystal display device  100 , for example a mobile phone, is mainly includes a liquid crystal panel  110 . The liquid crystal panel  110  includes a first transparent substrate  111 , a second transparent substrate  112 , and a liquid crystal layer  113 . A plurality of thin film transistors  111   a  are disposed on the first transparent substrate  111 . A plurality of color resist unit  112   a  are disposed on the second transparent substrate  112 . The liquid crystal layer  113  is filled in an enclosed structure formed by the first transparent substrate  111  and the second transparent substrate  112 . 
     Furthermore, the liquid crystal display device  100  further includes a first polarizer  120  disposed under the liquid crystal panel  110 , a second polarizer  130  disposed above the liquid crystal panel  110 , a backlight module  140  disposed under the first polarizer  120 , an optical adhesive layer (OCA: optical clear adhesive)  150  disposed above the second polarizer  130 , and a transparent cover  160  disposed above the optical adhesive layer  150 . 
     Furthermore, the liquid crystal display device  100  further includes a sensor  170 . In order to include the sensor  170  into the visible area of the liquid crystal panel  110 , the liquid crystal display device  100  is provided with a sensing area A, and in the sensing area A, the first polarizer  120 , the second polarizer  130 , and the backlight module  140  are provided with openings, respectively, and the sensor  170  is disposed under the openings. Therefore, an external light (as indicated by an arrow in  FIG. 1 ) can pass through the sensing area A of the liquid crystal display device  100 , so that the sensor  170  can perform a sensing operation. The sensor  170  such as a camera, a photosensitive sensor, an infrared sensor, and a fingerprint sensor. When the sensor  170  is a camera, a photo or film work can be performed through the sensing area A. 
     However, because such method of digging hole is adopted, a user can see the sensor  170  disposed under the liquid crystal panel  110  from outside no matter the liquid crystal display device  100  is in power-on or power-off state, so that the screen-to-body ratio of the liquid crystal display device  100  can be increased, but that also influences the overall aesthetic feeling of the liquid crystal display device  100  to a certain degree. 
     Therefore, it is necessary to provide an improved liquid crystal display device to solve the above technical problems. 
     SUMMARY OF INVENTION 
     A primary object of the present disclosure is to provide a liquid crystal display device including a sensor disposed in a visible area of a liquid crystal display panel. When the liquid crystal display device is in a power-off state, a user cannot see the sensor disposed under a liquid crystal panel from outside, and when the liquid crystal display device is in a power-on state, the user can see the sensor disposed under the liquid crystal panel from outside. 
     To achieve the above object, the present disclosure provides a liquid crystal display device, which comprises: a liquid crystal panel comprising a first transparent substrate, a second transparent substrate and a liquid crystal layer, wherein the liquid crystal layer is filled in an enclosed structure formed by the first transparent substrate and the second transparent substrate, and the liquid crystal panel is provided with a plurality of thin film transistors and a plurality of color resist units; a first polarizer disposed under the liquid crystal panel; and a second polarizer disposed above the liquid crystal panel; wherein the liquid crystal display device further includes a sensing area, and the plurality of thin film transistors are disposed in the sensing area, and wherein a backlight module is disposed under the first polarizer, and the backlight module has an opening corresponding to the sensing area; a polarization direction of the first polarizer is perpendicular to a polarization direction of the second polarizer; and the first transparent substrate is provided with the thin film transistors and a plurality of pixel units, and the second transparent substrate is provided with the color resist units, wherein in the sensing area, one of the thin film transistors is configured to drive one or more of the pixel units. 
     In one embodiment of the present disclosure, a sensor is disposed inside or below the opening of the backlight module. 
     In one embodiment of the present disclosure, the liquid crystal display device has a power-off state and a power-on state, and when the liquid crystal display device is in the power-off state, because the polarization direction of the first polarizer is perpendicular to the polarization direction of the second polarizer, an external light cannot pass through the sensing area of the liquid crystal panel, and when the liquid crystal display device is in the power-on state, because the thin film transistors control rotation of liquid crystal within the liquid crystal layer, the external light passes through the sensing area of the liquid crystal panel. 
     In one embodiment of the present disclosure, the pixel units are arranged in an array, and the thin film transistors are disposed among the pixel units driven thereby. 
     In one embodiment of the present disclosure, the pixel units are arranged in a row, and the thin film transistors are disposed on a side of the pixel units driven thereby. 
     In one embodiment of the present disclosure, the liquid crystal panel further comprises a frame area, and the thin film transistors are positioned in the frame area. 
     In one embodiment of the present disclosure, the first transparent substrate is an array substrate, and the second transparent substrate is a color filter substrate. 
     In one embodiment of the present disclosure, the liquid crystal display device further comprises a transparent cover plate, and the transparent cover plate is attached on the second polarizer by an optical adhesive layer. 
     To achieve the above object, the present disclosure further provides a liquid crystal display device, which comprises: a liquid crystal panel comprising a first transparent substrate, a second transparent substrate and a liquid crystal layer, wherein the liquid crystal layer is filled in an enclosed structure formed by the first transparent substrate and the second transparent substrate, and the liquid crystal panel is provided with a plurality of thin film transistors and a plurality of color resist units; a first polarizer disposed under the liquid crystal panel; and a second polarizer disposed above the liquid crystal panel; wherein the liquid crystal display device further includes a sensing area, and the plurality of thin film transistors are disposed in the sensing area, and wherein a backlight module is disposed under the first polarizer, and the backlight module has an opening corresponding to the sensing area. 
     In one embodiment of the present disclosure, a polarization direction of the first polarizer is perpendicular to a polarization direction of the second polarizer. 
     In one embodiment of the present disclosure, a sensor is disposed inside or below the opening of the backlight module. 
     In one embodiment of the present disclosure, the liquid crystal display device has a power-off state and a power-on state, and when the liquid crystal display device is in the power-off state, because the polarization direction of the first polarizer is perpendicular to the polarization direction of the second polarizer, an external light cannot pass through the sensing area of the liquid crystal panel, and when the liquid crystal display device is in the power-on state, because the thin film transistors control rotation of liquid crystal within the liquid crystal layer, the external light passes through the sensing area of the liquid crystal panel. 
     In one embodiment of the present disclosure, the first transparent substrate is provided with the thin film transistors and a plurality of pixel units, and the second transparent substrate is provided with the color resist units, wherein in the sensing area, one of the thin film transistors is configured to drive one or more of the pixel units. 
     In one embodiment of the present disclosure, the pixel units are arranged in an array, and the thin film transistors are disposed among the pixel units driven thereby. 
     In one embodiment of the present disclosure, the pixel units are arranged in a row, and the thin film transistors are disposed on a side of the pixel units driven thereby. 
     In one embodiment of the present disclosure, the liquid crystal panel further comprises a frame area, and the thin film transistors are positioned in the frame area. 
     In one embodiment of the present disclosure, the first transparent substrate is an array substrate, and the second transparent substrate is a color filter substrate. 
     In one embodiment of the present disclosure, the liquid crystal display device further comprises a transparent cover plate, and the transparent cover plate is attached on the second polarizer by an optical adhesive layer. 
     In the present disclosure, the sensing area is not used to display images, the liquid crystal display device does not have the plurality of color resist units disposed within the sensing area, and the polarization direction of the first polarizer is perpendicular to the polarization direction of the second polarizer, so that when the liquid crystal display device is in the power-off state, the user cannot see the sensor disposed under the liquid crystal panel from outside, and when the liquid crystal display device is in the power-on state, the user can see the sensor disposed under the liquid crystal panel from outside. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic partial cross-sectional view of a conventional liquid crystal display device. 
         FIG. 2  is a schematic partial cross-sectional view of a liquid crystal display device according to an embodiment of the present disclosure. 
         FIG. 3  is a schematic top view of a sensing area according to another embodiment of the present disclosure. 
         FIG. 4  is a schematic top view of a sensing area according to a further embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The foregoing objects, features, and advantages adopted by the present invention can be best understood by referring to the following detailed description of the preferred embodiments and the accompanying drawings. Furthermore, the directional terms described in the present invention, such as upper, lower, front, rear, left, right, inside, outer, side, etc., are only directions with reference to the accompanying drawings, so that the used directional terms are used to describe and understand the present invention, but the present invention is not limited thereto. 
     Referring to  FIG. 2 , which is a schematic partial cross-sectional view of a liquid crystal display device according to an embodiment of the present disclosure. A liquid crystal display device  200  of the present disclosure, for example a mobile phone, is mainly includes a liquid crystal panel  210 . The liquid crystal panel  210  includes a first transparent substrate  211 , a second transparent substrate  212 , and a liquid crystal layer  213 . The layer  213  is filled in an enclosed structure formed by the first transparent substrate  211  and the second transparent substrate  212 . 
     As shown in  FIG. 2 , the first transparent substrate  211 , for example, is an array substrate, and the second transparent substrate  212 , for example, is a color filter substrate. The first transparent substrate  211  is provided with a plurality of thin film transistors  211   a,  and the second transparent substrate  212  is provided with a plurality of color resist units  212   a.  However, the present disclosure is not limited thereto. In other possible embodiments, the plurality of thin film transistors  211   a  may also be disposed on the second transparent substrate  212 , and the plurality of color resist units  212   a  may also be disposed on the first transparent substrate  211 . 
     Furthermore, the liquid crystal display device  200  further includes a first polarizer  220  disposed under the liquid crystal panel  210 , a second polarizer  230  disposed above the liquid crystal panel  210 , a backlight module  240  disposed under the liquid crystal panel  210 , an optical layer (OCA: optical clear adhesive)  250  disposed above the second polarizer  230 , and a transparent cover  260  disposed above the optical adhesive layer  250 . A polarization direction of the first polarizer  220  is perpendicular to a polarization direction of the second polarizer  230 . The transparent cover  260 , for example, is a glass cover plate, and is attached on the second polarizer  230  by the optical adhesive layer. 
     Furthermore, the liquid crystal display device  200  further includes a sensor  270 . In order to include the sensor  270  into a visible area of the liquid crystal panel  210 , the liquid crystal display device  200  is provided with a sensing area B. The backlight module  240  in the sensing area B is correspondingly provided with an opening, and the sensor  270  is disposed inside or below the opening of the backlight module  240 . 
     In the present disclosure, because the sensing area B is not used to display images, the liquid crystal display device  200  does not have the plurality of color resist units  212   a  disposed within the sensing area B. 
     Furthermore, because the polarization direction of the first polarizer  220  is perpendicular to the polarization direction of the second polarizer  230 , and there is no opening in the sensing area B as in the prior art, when the liquid crystal the display device  200  is in a power-off state, an external light cannot pass through the sensing area B of the liquid crystal panel  210 . Conversely, when the liquid crystal display device  200  is in a power-on state, liquid crystal in the liquid crystal layer  213  can be control to rotate by the plurality of thin film transistors  211   a  on the first transparent substrate  211 , thereby allowing the external light to pass through the sensing area B of the liquid crystal panel  210 . 
     As mentioned above, when the liquid crystal display device  200  is in the power-off state, the user cannot see the sensor  270  disposed under the liquid crystal panel  210  from outside, and when the liquid crystal display device  200  is in the power-on state, the user can see the sensor  270  disposed under the liquid crystal panel  210  from outside, that is, the external light as indicated by an arrow in  FIG. 2  can pass through the sensing area B of the liquid crystal display device  200 , so that the sensor  270 , for example a camera, can perform a photo or film work. 
     Referring to  FIG. 3 , which is a schematic top view of a sensing area according to another embodiment of the present disclosure. In the present embodiment, a thin film transistor  211   a  is used to drive four pixel units  211   b  in a sensing area B. 
     As shown in  FIG. 3 , the plurality of pixel units  211   b  are arranged in an array, and the thin film transistor  211   a  is disposed among the four pixel units  211   b  driven thereby. Therefore, the present embodiment can reduce the number of the thin film transistors  211   a  in the sensing area B, and further increase a light entering amount by increasing an aperture ratio of the sensing area B. 
     Furthermore, the present disclosure is not limited thereto, and the thin film transistor  211   a  may be selectively used to drive  1  to N of the pixel units  211   b.    
     Referring to  FIG. 4 , which is a schematic top view of a sensing area according to a further embodiment of the present disclosure. The liquid crystal display device  200  and the sensing area B of the present embodiment are substantially similar to the above-mentioned embodiments, and therefore the same component names are continuously used, but the difference is that, in the embodiment, the plurality of pixel units  211   b  are arranged in a row and a plurality of The thin film transistor  211   a  is disposed on one side of the plurality of pixel units  211   b  driven thereby. Because the liquid crystal panel  210  further includes a frame area C, the thin film transistor  211   a  may be located in the frame area C. 
     Therefore, the present embodiment can reduce the number of the thin film transistors  211   a  in the sensing area B, and increase an aperture ratio of the sensing area B by moving the thin film transistor  211   a  to the frame area C of the liquid crystal panel  210 . 
     As mentioned above, in the prior art, a user can see the sensor disposed under the liquid crystal panel from outside no matter the liquid crystal display device is in power-on or power-off state. In the present disclosure, the sensing area B is not used to display images, the liquid crystal display device  200  does not have the plurality of color resist units  212   a  disposed within the sensing area B, and the polarization direction of the first polarizer  220  is perpendicular to the polarization direction of the second polarizer  230 , so that when the liquid crystal display device  200  is in the power-off state, the user cannot see the sensor  270  disposed under the liquid crystal panel  210  from outside, and when the liquid crystal display device  200  is in the power-on state, the user can see the sensor  270  disposed under the liquid crystal panel  210  from outside. 
     The present disclosure has been described with preferred embodiments thereof and it is understood that many changes and modifications to the described embodiment can be carried out without departing from the scope and the spirit of the invention that is intended to be limited only by the appended claims.