Patent Publication Number: US-2011050661-A1

Title: Liquid crystal display device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No(s). 098128729 filed in Taiwan, R.O.C. on Aug. 26, 2009, the entire contents of which are hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     The present invention relates to a liquid crystal display (LCD) device, and more particularly to an LCD device capable of adjusting a display parameter according to external light. 
     2. Related Art 
     LCD screens have been widely applied to various types of electronic devices such as mobile phones, digital cameras, and notebooks. Most LCD screens may have their display parameters, such as brightness, contrast, and color saturation, adjusted by users, so as to enable the users to obtain a color information presentation suitable for their own visual perception. 
     Taking portable electronic devices such as the notebooks as an example, the user may carry a notebook to different environments and occasions for use, for example, outdoors with sufficient light, in a coffee shop with darker light, or in an office with medium light intensity. Under different light conditions, the display parameter adjusted by the LCD screen may not be suitable for all the light conditions, for example, the brightness of the LCD screen should be raised in a darker environment or lowered in an environment with medium light intensity. However, in the prior art, the brightness of external light may be detected with a photosensitive element such as an photoresistor, thereby automatically adjusting the brightness of the LCD screen according to the detected brightness of the external light. 
     However, the actual operating environment of the user is not only featured in brightness with different intensities, but also in other aspects such as the difference between indoor and outdoor ambient light source colors (red, green, and blue (RGB) values) and the light source color difference between indoor illuminators like fluorescent lamps and light bulbs. Therefore, the color display parameter (such as the RGB values, warm colors, and cold colors) adjusted by the LCD screen may not satisfy all the light source color differences. In other words, although the conventional LCD screen can automatically adjust the brightness of the LCD screen with a photosensitive element, the user still needs to manually control the color display parameter, i.e., the color display parameter of the LCD screen cannot be automatically adjusted according to the ambient light source color. 
     SUMMARY OF THE INVENTION 
     Although the conventional LCD screen is capable of obtaining the brightness of external light with a photosensitive element and automatically adjusting the brightness of the LCD screen according to the brightness of the external light, the photosensitive element may not directly obtain light source color information about the external light. Therefore, the present invention is an LCD device capable of automatically adjusting a color display parameter according to light source color information. 
     The LCD device of the present invention comprises an LCD panel, a backlight module, a photosensitive module, and a controller. The LCD panel has a display region and a light-incident region. The backlight module is disposed below the LCD panel and corresponding to the display region. The photosensitive module is disposed below the LCD panel and corresponding to the light-incident region. The controller is electrically connected to the LCD panel and the photosensitive module. The backlight module provides a light source for the display of the LCD panel, and the photosensitive module receives an optical signal generated by the external light passing through the LCD panel. The external light is separated by a color filter in the LCD panel into an optical signal of RGB, and is received by the photosensitive module. The photosensitive module receives and converts the optical signal into an electrical signal, and transmits the electrical signal to the controller. Thereby, the controller is enabled to automatically adjust a color display parameter of the LCD panel according to the electrical signal. 
     In the LCD device of the present invention, a display region and a light-incident region are formed on the LCD panel, and a backlight module and a photosensitive module are respectively disposed in the two regions, so that the LCD panel may sense the color of the external light with the photosensitive module and adjust the color display parameter of the LCD panel according to the change of the color of the external light, in addition to maintaining the original LCD function with the light source projection of the backlight module. In this manner, the contrast effect between the display color of the LCD panel and the color of the external light as well as the display quality of the frame color can be improved. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description given herein below for illustration only, and thus are not limitative of the present invention, and wherein: 
         FIG. 1  is a schematic cross-sectional top view of an LCD device according to an embodiment of the present invention; 
         FIG. 2  is a schematic front view of the LCD device according to the embodiment of the present invention; 
         FIG. 3  is a schematic view illustrating an operation of the LCD device according to the embodiment of the present invention; 
         FIG. 4  is a schematic cross-sectional top view of the LCD device with two light-incident regions and two photosensitive modules according to the embodiment of the present invention; and 
         FIG. 5  is a schematic front view of the LCD device with two light-incident regions and two photosensitive modules according to the embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The detailed features and advantages of the present invention are described below in great detail through the following embodiments, the content of the detailed description is sufficient for those skilled in the art to understand the technical content of the present invention and to implement the present invention there accordingly. Based upon the content of the specification, the claims, and the drawings, those skilled in the art can easily understand the relevant objectives and advantages of the present invention. The following embodiments are intended to describe the present invention in further detail, but not intended to limit the scope of the present invention in any way. 
     Referring to  FIG. 1 , the LCD device of the present invention comprises an LCD panel  10 , a backlight module  20 , a photosensitive module  30 , and a controller  40 . The controller  40  is a microcontroller unit (MCU), and electrically connected to the LCD panel  10  and the photosensitive module  30 . The LCD panel  10  substantially comprises a first polarization plate  102  and a second polarization plate  110 , and a color filter  104 , a liquid crystal layer  106 , and a thin-film transistor (TFT) module  108  are disposed between the first and second polarization plates  102  and  110 . The liquid crystal layer  106  comprises a plurality of liquid crystal molecules, and the TFT module  108  comprises electronic elements (not shown) such as a drive integrated circuit (IC) and a printed circuit board (PCB). 
     Referring to  FIGS. 1 and 2 , a display region A 1  and a light-incident region A 2  are respectively defined on the LCD panel  10 . The backlight module  20  and the photosensitive module  30  are disposed below the LCD panel  10  (i.e., at a side adjacent to the second polarization plate  110 ). The backlight module  20  is disposed corresponding to the display region A 1  of the LCD panel  10 , and the photosensitive module  30  is disposed corresponding to the light-incident region A 2  of the LCD panel  10 . The photosensitive module  30  is formed by light sensor elements which are capable of receiving an optical signal and converting the optical signal into an electrical signal, such as a charge coupled device (CCD), a complementary metal-oxide-semiconductor (CMOS), or a light sensor array composed of a plurality of photoelectric sensors. 
     Referring to  FIG. 3 , when the LCD device of the present invention is in use, the backlight module  20  provides a uniform light source L 1  with sufficient brightness and projects the light source onto the LCD panel  10 . Non-polarized light is converted into polarized light by the second polarization plate  110 . Meanwhile, a voltage of the drive IC in the TFT module  108  is changed, so as to enable the liquid crystal molecules in the liquid crystal layer  106  to generate a motion and alter their original arrangement accordingly by controlling the electric field of the drive IC. For example, the liquid crystal molecules stand upright or twist in the liquid crystal layer  106 , so as to control the transmittance of the light source L 1  provided by the backlight module  20 . Therefore, when the light emitted by the light source L 1  passes through the liquid crystal layer  106 , the advancing direction of a part of the light is rotated to smoothly pass through the color filter  104  and the first polarization plate  102 , and the other part of the light that is not rotated is blocked, thereby controlling the presentation of color frames on the LCD panel  10 . This is a common frame display mode of the LCD panel  10 , and is not a technical feature that the present invention is intended to emphasize, so the detailed structures and operating principle thereof will not be described again herein. 
     Referring to  FIGS. 1 to 3 , when the LCD device provides the light source L 1  on the LCD panel  10  by using the backlight module  20  and performs a frame display operation in the display region A 1  of the LCD panel  10 , external light L 2  present in the operating environment of the LCD device enters the LCD panel  10  through the light-incident region A 2  of the LCD panel  10  at the same time. Similarly, when the external light L 2  enters the LCD panel  10 , non-polarized light is converted into polarized light by the first polarization plate  102 , then separated by the color filter  104  and implemented by color processing of RGB, and finally passes through the TFT module  108  and the second polarization plate  110  to generate an optical signal of RGB of the external light L 2 . The optical signal is received by the photosensitive module  30 . 
     After receiving the optical signal, the photosensitive module  30  converts the optical signal into an electrical signal based on intensities of the RGB of the external light L 2  in the optical signal, and transmits the electrical signal to the controller  40 . The controller  40  adjusts a color display parameter of the LCD panel  10  according to the electrical signal, so that the display frame color presented by the LCD panel  10  can be automatically adjusted to the optimal with the light source color of the external environment of the LCD device. For example, when the user operates the LCD device in an environment with a yellowish light color, the external light in a yellowish color passes through the LCD panel  10  from the light-incident region A 2  of the LCD panel  10 , and is received and converted by the photosensitive module  30  into an electrical signal. The photosensitive module  30  then transmits the electrical signal to the controller  40 . The controller  40  adjusts the color display parameter of the LCD panel  10  based on the information about the yellowish color conveyed by the electrical signal, so that a contrast effect between the frame color displayed by the LCD panel  10  and the color of the external light is generated. 
     Further, in order to increase the light color sensing speed of the photosensitive module  30  to the operating environment of the LCD device and more accurately grasp the change and uniformity of the color of the external light, a plurality of photosensitive modules  30  is disposed in the LCD device and a plurality of light-incident regions A 2  is disposed on the LCD panel  10 . For example, the above purpose can be realized by disposing two photosensitive modules  30  in the LCD device and disposing two light-incident regions A 2  on the LCD panel  10  (as shown in  FIGS. 4 and 5 ). The number of the photosensitive module  30  and the light-incident region A 2  is for illustration only, instead of limiting the present invention. 
     In the LCD device of the present invention, a light-incident region is formed on the LCD panel and a photosensitive module is disposed corresponding to the light-incident region by properly reducing the size of the backlight module in the display region (light transmission range) on the LCD panel. In this manner, the LCD device may sense the color of the external light with the photosensitive module and adjust the color display parameter of the LCD panel according to the detected photoelectric signal, in addition to maintaining the original color frame display function. Thereby, the contrast effect between the display color of the LCD panel and the color of the external light as well as the display quality of the frame color can be improved.