Abstract:
A backlight module of a display provides a backlight controlled by a switch. A first electrochromic film comprises a plurality of first electrochromic devices which may each be powered on to appear white or transparent, and a first power supply module. A second electrochromic film comprises a plurality of second electrochromic devices which may each be powered to appear black or transparent, and a second power supply module. The first electrochromic film is positioned between the backlight module and the second electrochromic film. A controller applies voltages to the first electrochromic devices and to the second electrochromic devices to control appearances of each individual first electrochromic devices and each individual second electrochromic devices.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    The present disclosure relates to a display, and particularly to a power saving display. 
         [0003]    2. Description of Related Art 
         [0004]    An electronic display device (such as a mobile phone or e-book) is generally provided with a backlight module, but if the backlight module is turned off, user cannot see the display. Therefore, the backlight module must remain turned on all the time, which consumes a large amount of power. 
         [0005]    Therefore, it is necessary to provide an effective power saving display. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    Many aspects of the display can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present display. In the drawings, all the views are schematic. 
           [0007]      FIG. 1  is a schematic view of the display structure including first and second power supply modules. 
           [0008]      FIG. 2  is a schematic view of the first power supply module of the display of  FIG. 1 . 
           [0009]      FIG. 3  is a schematic view of the second power supply module of the display of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0010]    Referring to  FIG. 1 , the present disclosure provides a display  100  which includes a microprocessor  10 , a backlight module  20 , a switch  30 , a first electrochromic film  40 , a first power supply module  50 , a second electrochromic film  60 , a second power supply module  70 , and a controller  90 . The first electrochromic film  40  is positioned between the backlight module  20  and the second electrochromic film  60 . The microprocessor  10  receives an image, the image including luminance information governing brightness of each pixel in the display. The microprocessor  10  can recognize a luminance value of each pixel in the display from the image data. Classified according to the luminance values, the information for plurality of pixels of an image includes a plurality of white pixels and a plurality of black pixels. For example, a luminance value of 255 would be completely white; a luminance value of 0 would be a completely black. The backlight module  20  provides a backlight. The switch  30  controls turning on and turning off of the backlight module  20 . Specifically, when the switch  30  is in a first state, the backlight module  20  is on and when the switch  30  is in a second state, the backlight module is off 
         [0011]    The first electrochromic film  40  is set on the backlight module  20 . The first electrochromic film  40  includes a matrix-like arrangement of a plurality of first electrochromic devices  41 . Each of the plurality of first electrochromic devices  41  corresponds to a plurality of pixels of the image. In the present embodiment, the first electrochromic device  41  is capable of changing its ability to refract or reflect light under the influence of an applied voltage. The first power supply module  50  electrically connected to the first electrochromic film  40 . As shown in  FIG. 2 , the first power supply module  50  includes a plurality of first power connections  51  corresponding to the plurality of first electrochromic devices  41 . Each of the first power connections  51  electrically connected to the first electrochromic device  41  provides two different values of voltage, so that a first electrochromic device  41  exhibits transparency or blackness after being switched on. The second electrochromic film  60  is set on the first electrochromic film  40  farthest from the backlight module  20 . The second electrochromic film  60  includes a matrix-like arrangement of a plurality of second electrochromic devices  61 . Each of the second electrochromic devices  61  corresponds to the first electrochromic devices  41  and corresponds to a plurality of pixels of the image. In the present embodiment, the second electrochromic device  61  has properties similar to those of the first electrochromic device  41 . The second power supply module  70  electrically connected to the second electrochromic film  60 , as shown in  FIG. 3 . Each of a second power connections  71  supplies power to the second electrochromic device  61 , in providing two different voltage values, so that the second electrochromic device  61  exhibits transparency or whiteness after switched on. The optical properties (reflectance, transmittance, absorptance) of the first electrochromic device  41  and of the second electrochromic device  61 , under the action of an electric field allow stable and reversible appearances. 
         [0012]    Specifically, as shown in  FIG. 4 , the first electrochromic device  41  includes a sequential stacking, in the following orders, a first transparent base layer  401 , a first transparent conductive layer  402 , an electrochromic layer  403 , an electrolyte layer  404 , an ion storage layer  405 , a second transparent conductive layer  406  and a second transparent base layer  407 . In the present embodiment, the first transparent base layer  401  and the second transparent base layer  407  are made of glass; the first transparent conductive layer  402  and the second conductive layer  406  are made of indium tin oxide (ITO); the electrochromic layer  403  is made of electrochromic materials; the electrolyte layer  404  is made of conductive materials, such as lithium perchlorate or sodium perchlorate solutions or solid electrolytic materials; the ion storage layer  405  is made of electrochromic materials, wherein an electrochromic properties of the electrochromic materials is in contrast to the electrochromic layer; if anodic oxidation electrochromic materials are used in the electrochromic layer  403 , then the ion storage layer  405  uses cathodic reduction electrochromic materials. 
         [0013]    An operating principle of the first electrochromic device  41  is as follows: when a certain potential difference exists between the first transparent conductive layer  402  and second transparent conductive layer  406 , since the electrochromic layer  403  is made of electrochromic materials, an oxidation-reduction reaction occurs under an influence of the voltage, and an appearance of the electrochromic layer changes. The ion storage layer  405  stores balancing counter-ions when the oxidation-reduction reaction occurs in the electrochromic layer  403 , to maintain the whole system charge balance. The ion storage layer  405  and the electrochromic layer  403  play either an appearance overlay or a complementary role. That is, the first electrochromic device  41  subjected to the electric field allows an electrochemical oxidation-reduction reaction, and gains or loses electrons, changing an appearance of the first electrochromic device  41 . 
         [0014]    The second electrochromic device  61  and the first electrochromic device  41  have basically the same structure, but the material of the electrochromic layer of the second electrochromic device  61  is different to the first electrochromic device  41 . The controller  90  and the microprocessor  10  and switch  30  carry out electrical functions, thus the backlight module  20  may be on or off depending on a luminance values. The voltage of the first power supply module  50  applied to the first electrochromic device  41  and the voltage of the second power supply module  70  applied to the second electrochromic device  61  is changed in accordance with the luminance values of the pixels, to make the display  100  display a legible image. Specifically, when the switch  30  in the first state, the backlight module  20  turns on. At this moment, the controller  90  controls the second electrochromic devices  61  corresponding to the white pixels of the image, to switch on and become transparent, and the first electrochromic devices  41  corresponding to the white pixels of the image to switch on and become transparent; simultaneously, the controller  90  controls the second electrochromic devices  61  corresponding to the black pixels of the image to switch on and become transparent, the first electrochromic devices  41  corresponding to the black pixels of the image to switch on and become black. When the switch  30  in the second state, the backlight module  20  turns off. At this moment, the controller  90  controls the second electrochromic devices  61  corresponding to the white pixels of the image to switch on and turn white, and the first electrochromic devices  41  corresponding to the white pixels of the image to switch on and turn transparent; simultaneously, the controller  90  controls the second electrochromic devices  61  corresponding to the black pixels of the image to switch on and turn transparent, and the first electrochromic devices  41  corresponding to the black pixels of the image to switch on and become black. 
         [0015]    The working process of the display  100  is as follows: when an external lighting is not sufficient, user turns on the backlight module  20  to see a page better. The second electrochromic devices  61  corresponding to the white pixels of the image to switch on and turn transparent, simultaneously the first electrochromic devices  41  corresponding to the white pixels of the image are also turned transparent, enabling an emitted light of the backlight module  20  to pass through both first and second devices  41  and  61 , making background of the display  100  appears white, as a result of emitted color of the backlight. The second electrochromic devices  61  corresponding to the black pixels of the image are switched on and turn transparent, simultaneously the first electrochromic devices  41  corresponding to the black pixels of the image are switched on and turn black, enabling the emitted light of the backlight module  20  to pass through the second electrochromic devices  61  corresponding to the black pixels of the image, then absorbed by the first electrochromic devices  41 , thus no light from those points enters into the eye of user, the display  100  displaying black constituting the image. The white and the black together compose the image. 
         [0016]    When the external lighting is sufficient, the user may turn off the backlight module  20 . The second electrochromic devices  61  corresponding to the white pixels of the image to switch on and turn white, simultaneously the first electrochromic devices  41  corresponding to the white pixels of the image to switch on and turn transparent. The external lighting is reflected by the second electrochromic devices  61  corresponding to the white pixels of the image, making the background of the display  100  appears white. The second electrochromic devices  61  corresponding to the black pixels of the image to switch on and turn transparent, simultaneously the first electrochromic devices  41  corresponding to the black pixels of the image to switch on and turn black, the external lighting to pass through the second electrochromic devices  61  corresponding to the black pixels of the image is absorbed by the first electrochromic devices  41 , and thus no light enters into the eye of user, the display  100  displaying black. The white and the black compose the image. 
         [0017]    Compared to a prior art, the display  100  of the present disclosure allows the user to make use of ambient or external lighting to see and read the display when the external lighting is strong enough. When the external lighting is not sufficient, the user may always turn on the backlight module  20  to observe the image. 
         [0018]    In the present embodiment, boost and buck circuits are provided inside the first power connections  51  and the second power connections  71 , so that voltages of the first power connections  51  and of the second power connections  71  can be directly adjusted in accordance with an instructions of the controller  90 . In another embodiment, the first power connections  51  and the second power connections  71  include two sub-power supplies, enabling output different voltage values. 
         [0019]    Although the present disclosure has been specifically described on the basis of this exemplary embodiment, the disclosure is not to be construed as being limited thereto. Various changes or modifications may be made to the embodiment without departing from the scope and spirit of the disclosure.