Patent Publication Number: US-2010109997-A1

Title: Display device with backlight local area illumination control circuit

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a radio frequency identification system that is capable of preventing signal collision, in particular, to a radio frequency identification system with multi-band transmission for preventing signal collision. 
     2. Related Art 
     A conventional liquid crystal displays (LCD) is generally comprised of a displaying panel and a backlight module. The displaying panel displays an image thereon by controlling pixels thereof. The backlight module is positioned at the rear side of the display device to provide a backlight source. The illuminants that are ordinarily used in a backlight module include a cold cathode fluorescent lamps (CCFL) and light-emitting diodes (LEDs). For all the applications currently known, for image pre-displaying in an electronic device, the backlight module is set in a completely activated condition and switches that control the pixels in the displaying panel determine if to pass the light from the backlight source. Thus, for many electronic devices, such as a notebook computer, a liquid crystal displaying screen, a mobile phone, and personal digital assistant (PDA), the backlight module is a high power consumption component and it remains a challenge to be solved to put the backlight module in an operation of best performance. 
     For example, U.S. Pat. No. 6,457,279 discloses a touch panel structure that has a backlight module using a CCFL as an illuminant, together with a reflector board, a light guide, a diffuser board, and a polarization conversion board, which reflect, guide, and uniformly distribute the light for projection onto the liquid crystal panel to provide brightness for image displayed on the liquid crystal panel. 
     However, the illuminant of the conventional backlight module can only be set in a full-screen-area-on condition. In other words, even only a local area that is a portion of the full screen is needed to be set in operation, the illuminant of the backlight module still has to be turned on for the whole screen area and it is in generally impossible to make any adjustment in response to a desired area for displaying operation, and consequently, unnecessary power consumption occurs. For a portable electronic device, such as mobile phone, the capacity of a battery pack is very limited and unnecessary consumption of power will directly affect the usable time of the mobile phone. For the illuminant used in the conventional backlight module, both a CCFL and an LED, is subjected to a limitation imposed by the lifespan thereof that is closely relevant to the time period that it is set in operation to give off light. 
     SUMMARY OF THE INVENTION 
     In view of the above discussed problems of the known techniques, the present invention provides a display device that eliminates unnecessary power consumption by employing a backlight local area illumination control circuit to control the driving and thus light emission of each illuminant of a backlight module so that the backlight module of a display device is operated to selectively only illuminate a local illumination zone thereof corresponding to a global or local displaying area of the display device. 
     In an embodiment of the present invention, a display device with a backlight local area illumination control circuit is provided, which employs a backlight local area illumination control circuit to control an illumination zone of the backlight module of the display device. The backlight local area illumination control circuit includes a plurality of illuminants, an illuminant controller, and an illuminant driving circuit, and the illuminant driving circuit includes a first driving circuit and a second driving circuit. Based on a backlight illumination zone selection signal received, the illuminant controller selectively drives the illuminants of the backlight module by means of the first driving circuit and the second driving circuit so as to form a local illumination zone in the backlight module corresponding to a local displaying area in which a target image is to be displayed on the global displaying area to have the target image displayed in the local displaying area of the display device. 
     The present invention uses a backlight local area illumination control circuit to control an illumination zone of a backlight module of a display device in order to prevent the illuminants of the backlight module from being set in an activated condition for a long while for the purposes of effectively reducing unnecessary power consumption and to prevent the illuminants of the backlight module from unnecessary activation for the purposes of extending the service life of the illuminants. 
     These and other features, aspects, and advantages of the present invention will become better understood with reference to the following description and appended claims. It is to be understood that both the foregoing general description and the following detailed description are examples, and are intended to provide further explanation of the invention as claimed. 
    
    
     
       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 is not limitative of the present invention, and wherein: 
         FIG. 1  shows a system block diagram in accordance with a first embodiment of the present invention; 
         FIG. 2  is an exploded view showing a display device in accordance with the first embodiment of the present invention; 
         FIG. 3  is a schematic view illustrating a backlight local area illumination control circuit in accordance with the first embodiment of the present invention; 
         FIG. 4  is a schematic view illustrating a global illumination zone in accordance with the first embodiment of the present invention; 
         FIG. 5  is a schematic view illustrating a local illumination zone in accordance with the first embodiment of the present invention; and 
         FIG. 6  is a schematic view illustrating a backlight local area illumination control circuit in accordance with a second embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description refers to the same or the like parts. 
     With reference to  FIGS. 1 and 2 , wherein  FIG. 1  shows a system block diagram in accordance with a first embodiment of the present invention and  FIG. 2  shows an exploded view of a display device in accordance with the first embodiment of the present invention, as shown, an image data source  10  applies a RGB analog signal that is comprised of red, green, and blue components to an analog to digital converter (ADC)  11  for conversion of the analog signal into a digital signal, which is then applied to a scaler  12 . The scaler  12  performs adjustment with respect to image-related parameters regarding to image resolution or shape and size contained in the digital signal provided by the analog to digital converter  11 . 
     The scaler  12  is connected to a microprocessor unit  13  and an on-screen display (OSD)  14 . The OSD  14  allows for fine adjustment of displaying-related parameters, such as brightness and contrast of screen displaying and horizontal and vertical positioning, of the image data that have been subjected to adjustment realized through the scaler  12 . Further, the OSD  14  can be embedded or optional according to the numbers of language and font that the system can support. 
     During the processing of image data, the microprocessor unit  13  carries out reception and conversion of the image signal and interlaced scanning. In addition, it also helps the OSD  14  in appearance adjustment and font conversion. The scaler  12  transmits the adjusted and integrated image data as an image data signal s 1  to a display panel driving circuit  100 . The a display panel driving circuit  100  comprises a timing controller  2 , a data driving circuit  31 , and a gate driving circuit  32  and functions to control the pixel units of a display panel  41  of a display device  4 . 
     The timing controller  2  comprises an image signal source connection portion  21 , a data driving circuit connection port  22 , and a gate driving circuit connection port  23 . The image signal source connection portion  21  of the timing controller  2  receives the image data signal s 1  and in turn provides a data driving circuit control signal s 2  through the data driving circuit connection port  22  thereof to the data driving circuit  31 . The data driving circuit  31  comprises a plurality of data lines S 1 -S 10  connected to the display panel  41  for transmitting the RGB-indicative digital signals to desired pixel units. 
     The timing controller  2  further provides a gate control signal s 3  through the gate driving circuit connection port  23  thereof to the gate driving circuit  32 . The gate driving circuit  32  comprises a plurality of gate lines G 1 -G 10  connected to the pixel units on the display panel  41  of the display device  4  for controlling and driving a desired image displaying area on the display panel  41  through the gate control signal s 3 . 
     The display device  4  comprises a backlight module  42  to serve as a backlight source for the display device  4 . A diffusion board  43  is arranged between the backlight module  42  and the display panel  41 . The display device  4  controls an illumination zone of the backlight module  42  through a backlight local area illumination control circuit  200 . The backlight local area illumination control circuit  200  comprises a plurality of illuminants  421 , an illuminant controller  5 , and an illuminant driving circuit  6 . The illuminant controller  5  is connected to the illuminant driving circuit  6  and selectively drives each illuminant  421  of the backlight module  42  in accordance with a backlight illumination zone selection signal s 4  provided by the microprocessor unit  13 . 
     Referring to  FIG. 3 , which is a schematic view of the backlight local area illumination control circuit in accordance with a first embodiment of the present invention, as shown, the illuminants  421  are arranged in a matrix in the backlight module  42  and are set corresponding to the display panel  4  so that the light generated by each illuminant  421  is projected toward and thus illuminates the display panel  41  and a global illumination zone W that corresponds to a full displaying area of the display panel  41  is defined. 
     In the embodiment illustrated, the illuminant driving circuit  6  comprises a first driving circuit  61  and a second driving circuit  62 . The first driving circuit  61  comprises a plurality of first driving control lines C 1 -C 10 , each being connected to a terminal of a corresponding one of the illuminants  421  in each column of the matrix. The second driving circuit  62  comprises a plurality of second driving control lines L 1 -L 10 , each being connected to an opposite terminal of a corresponding one of the illuminants  421  in each row of the matrix. 
     The illuminant controller  5  receives the backlight illumination zone selection signal s 4  and generates a first driving signal s 41  to the first driving circuit  61  to provide a driving voltage to the illuminants  421  through the first driving control lines C 1 -C 10 . The illuminant controller  5  also generates a second driving signal s 42  to the second driving circuit  62  to provide a driving voltage to the illuminants  421  through second driving control lines L 1 -L 10 . When an illuminant  421  is simultaneously driven by both the first driving circuit  61  and the second driving circuit  62 , the illuminant  421  is enabled and gives off light. 
     Also referring to  FIG. 4 , which is a schematic view illustrating a global illumination zone in accordance with the first embodiment of the present invention, when the display panel  41  of the display device  4  needs to display images in the global illumination zone thereof, the backlight module  42  enables all the illuminants  421  that are covered in the global illumination zone W to give off light. By simultaneously driving all the illuminants  421  through both the first driving control lines C 1 -C 10  of the first driving circuit  61  and the second driving control lines L 1 -L 10  of the second driving circuit  62 , the global illumination zone W is made illuminating simultaneously. 
     Referring to  FIG. 5 , which is a schematic view illustrating a local illumination zone in accordance with the first embodiment of the present invention, to display an image in a local displaying area, the illuminant controller  5  selectively drives the illuminants  421  of the backlight module  42  in accordance with the backlight illumination zone selection signal s 4 . 
     As shown, by activating the first driving control lines C 4 -C 7  of the first driving circuit  61  and the second driving control lines L 4 -L 7  of the second driving circuit  62  to simultaneously drive the illuminants  421  associated therewith, the backlight module  42  allows the formation of a local illumination zone W 1  in accordance with a local displaying area of the global displaying area in which a target image is to be displayed so that the local illumination zone W 1  is made illuminating to display the target image on the selected local displaying area. 
       FIG. 6  shows a backlight local area illumination control circuit in accordance with a second embodiment of the present invention, as shown, the operation of the second embodiment is similar to that of the first embodiment so that identical components bear the same reference numerals and will not be repeatedly described. A difference between the two embodiment resides in that the illuminants  421 ′ of the backlight local area illumination control circuit  200  in the second embodiment are arranged at location close to and along two side edges of the backlight module  42  and are respectively connected to the first driving circuit  61  and the second driving circuit  62  of the illuminant controller  5 . 
     When the illuminant controller  5  controls the first driving control lines C 4 -C 7  of the first driving circuit  61  and the second driving control lines L 4 -L 7  of the second driving circuit  62  in accordance with the received backlight illumination zone selection signal s 4  so as to simultaneously drive the illuminants  421  covered by the control lines for giving off light, the illuminants  421 ′ that are thus driven give off lights that are projected to and intersect in the corresponding local illumination zone W 2 . 
     Additional advantages and modifications will readily occur to those proficient in the relevant fields. The invention in its broader aspects is therefore not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.