Abstract:
A multi-mode Liquid Crystal Display (LCD) capable of functioning in a multi-mode, a monochrome reflective mode and a color transmissive mode. One embodiment provides an LCD with color filters only over most or all of the transmissive part of a pixel but only part of the reflective portion of a pixel, enabling readability in the ambient light. Embodiments eliminate the black matrix mask used typically in color filter creation. Additionally, an embodiment provides diagonal pixels to improve the resolution of the LCD in the color transmissive mode. Further, an embodiment enables the light to switch between two colors, while a third color (typically green) is always on, thereby decreasing the required frame rate of the LCD, when used in the hybrid field sequential approach. Yet another embodiment creates colors from the backlight, eliminating the need for color filters. Another embodiment involves use of color filters over only the green pixels, eliminating the need for using additional masks for making the color filter array.

Description:
BENEFIT CLAIM 
       [0001]    This application claims the benefit, under 35 U.S.C. 119(e), of prior provisional application 61/081,076, filed Jul. 16, 2008, the entire contents of which is hereby incorporated by reference as if fully set forth herein. 
     
    
     TECHNICAL FIELD 
       [0002]    The present disclosure relates, in general, to a display. More specifically, the disclosure relates to a multi-mode Liquid Crystal Display (LCD). 
       BACKGROUND 
       [0003]    The approaches described in this section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section. 
         [0004]    The increase in the use of displays in various electronic components has increased the pressure on display manufacturers to provide components that provide better performance. The performance parameters include readability, power consumption, resolution, cost, and sunlight readability. Display manufacturers employ various techniques to improve performance based on these parameters. 
         [0005]    One such technique is used in transflective LCDs. Each pixel of the transflective LCD has a reflective part and a transmissive part. The transmissive part and the reflective part also comprise sub-pixels. Each of the sub-pixels has color filters that impart color to the pixel. Additionally, each of the sub-pixels is arranged horizontally or vertically. This requires three or more sub-pixels to represent a color in the LCD. 
         [0006]    In the above-mentioned approach, color filters are placed over both the transmissive part and the reflective part. Therefore, the light passing through the color filters is attenuated, making the reflective mode, with the backlight off, dim and difficult to read. Further, the backlight, in the transmissive mode, requires more power to achieve a high-resolution display. Further, this practice reduces the resolution when white, black or shades of grey are displayed, as it takes multiple color subpixels to represent a shade of neutral grey, or white. Text is most often depicted in black, white and grey and higher resolution text has been shown to dramatically improve readability and legibility. See, for example, Steven L. Wright, Ian L. Bailey, Kuang-Mon Tuan, Richard T. Wacker, “Resolution and Legibility: A comparison of TFTLCDs and CRTs” SID Digest, 24-03, 1999; Yoshitake, Ryoji and Kubota, Satoru, “The Relationship between Pixel Density and Readability on Computer Displays—Effectiveness of an Anti-aliased Font on a High Density LCD” SID 2003 Digest, pp 296-299. 
         [0007]    In view of the foregoing discussion, there exists a need for a technique that produces a high resolution in LCDs that are roomlight readable with the backlight off, and sunlight readable. Additionally, a need exists to develop an LCD that shows a high resolution in black, white and shades of grey. 
       SUMMARY 
       [0008]    In an embodiment, an LCD provides better resolution and readability as compared to existing LCDs. 
         [0009]    In an embodiment, the power required by the LCD is reduced. 
         [0010]    In an embodiment, a sunlight readable display in the LCD is provided. 
         [0011]    In an embodiment, a roomlight readable display in the LCD is provided. 
         [0012]    In an embodiment, an LCD comprises color filters over the transmissive part of a pixel, and color filters only over a portion of the reflective part of the pixel, enabling shifting of the monochrome white-point and a strong readability in ambient light. In an embodiment, the black matrix mask used typically in color filter creation is eliminated. Additionally, an embodiment provides diagonal pixels to improve the resolution of the LCD in the color transmissive mode. Further, an embodiment enables the light to switch between two colors, while a third color (typically green) is always on, thereby, decreasing the required frame rate of the LCD, when used in the hybrid field sequential approach. In an embodiment, colors are created from the backlight, thereby eliminating the need for color filters. In an embodiment, color filters are used over only the green pixels, thereby eliminating the need for using additional masks for making the color filter array. 
         [0013]    In an embodiment, a multi-mode Liquid Crystal Display comprises a light source for illuminating the multi-mode display; a first polarizer for aligning the plane of polarization of light from the light source to a first plane; a second polarizer for aligning the plane of polarization of the light from the light source to a pre-defined second plane; a first substrate and a second substrate, the first substrate and the second substrate being interposed between the first polarizer and the second polarizer; and a plurality of pixels, each of the plurality of pixels being positioned at the first substrate, each of the plurality of pixels comprising a reflective part and a transmissive part, wherein the reflective part has only part of a color filter, and at least part of the transmissive part comprises one or more color-filters that mostly or completely cover the transmissive part of the pixel. 
         [0014]    In an embodiment, the reflective part occupies opposite corners of the plurality of pixels. In an embodiment, the color filter associated with the reflective part of the pixel creates a monochrome white point for the entire pixel. In an embodiment, the transmissive part occupies a center of the plurality of pixels. In an embodiment, a spectrum of color is generated from the light from the light source using a diffractive or a micro-optical film. 
         [0015]    In an embodiment, the transmissive part is diagonally arranged. In an embodiment, the one or more color-filters are of different thicknesses. In an embodiment, the one or more color-filters are of a same thickness. 
         [0016]    In an embodiment, the multi-mode Liquid Crystal Display further comprises one or more colorless spacers placed over the reflective part. In an embodiment, the one or more colorless spacers are of a same thickness. In an embodiment, the one or more colorless spacers are of different thicknesses. 
         [0017]    In an embodiment, the multi-mode Liquid Crystal Display further comprises a driver circuit to provide pixel values to a plurality of switching elements, wherein the plurality of switching elements determines the light transmitting through the transmissive part. In an embodiment, the driver circuit further comprises a Transistor-Transistor-Logic interface. In an embodiment, the multi-mode Liquid Crystal Display further comprises a timing control circuit to refresh the pixel values of the multi-mode Liquid Crystal Display. 
         [0018]    In an embodiment, the multi-mode Liquid Crystal Display as described herein forms a part of a computer, including but not limited to a laptop computer, notebook computer, and netbook computer. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    Various embodiments of the present invention will herein after be described in conjunction with the appended drawings, provided to illustrate and not to limit the present invention, wherein like designations denote like elements, and in which: 
           [0020]      FIG. 1  is a schematic of a cross section of a pixel of a LCD; 
           [0021]      FIG. 2  illustrates the arrangement of nine pixels of the LCD; 
           [0022]      FIG. 3  illustrates the functioning of the LCD in a monochrome reflective mode; 
           [0023]      FIG. 4  illustrates the functioning of the LCD in a color transmissive mode by using a partial color filtered approach; 
           [0024]      FIG. 5  illustrates the functioning of the LCD in a color transmissive mode by using a hybrid field sequential approach; and 
           [0025]      FIG. 6  illustrates the functioning of the LCD in a color transmissive mode by using a diffractive approach. 
       
    
    
     DETAILED DESCRIPTION 
       [0026]    Various embodiments of the present invention relate to a Liquid Crystal Display (LCD) that is capable of functioning in multi-mode, a monochrome reflective mode and a color transmissive mode. Various modifications to the preferred embodiments and the generic principles and features described herein will be readily apparent to those skilled in the art. Thus, the present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features described herein. 
         [0027]      FIG. 1  is a schematic of a cross section of a pixel  100  of a LCD. Pixel  100  comprises a liquid crystal material  104 , a pixel electrode  106 , a common electrode  108 , a reflective part  110 , a transmissive part  112 , substrates  114  and  116 , spacers  118   a  and  118   b , a first polarizer  120 , and a second polarizer  122 . In an embodiment, a light source  102  or an ambient light  124  illuminates pixel  100 . Examples of light source  102  include, but are not limited to, Light Emitting Diodes backlights (LEDs), Cold-Cathode Fluorescent Lamps backlights (CCFLs), and the like. Ambient light  124  can be sunlight or any external source of light. In an embodiment, liquid crystal material  104 , which is an optically active material, rotates the axis of the polarization of the light from light source  102  or ambient light  124 . Liquid crystal  104  can be a Twisted Nematic (TN), an Electrically Controlled Birefringence (ECB) and the like. In an embodiment, the rotation of the plane of the light is determined by the potential difference applied between pixel electrode  106 , and common electrode  108 . In an embodiment, pixel electrode  106  and common electrode  108  can be made of Indium Tin Oxide (ITO). Further, each pixel is provided with a pixel electrode  106 , while common electrode  108  is common to all the pixels present in the LCD. 
         [0028]    In an embodiment, reflective part  110  is electrically conductive and reflects ambient light  124  to illuminate pixel  100 . Reflective part  110  is made of metal and is electrically coupled to pixel electrode  106  thereby providing the potential difference between reflective part  110  and common electrode  108 . Transmissive part  112  transmits light from light source  102  to illuminate pixel  100 . Substrates  114  and  116  enclose liquid crystal material  104 , pixel electrode  106  and common electrode  108 . In an embodiment, pixel electrode  106  is located at substrate  114 , and common electrode  108  is located at substrate  116 . Additionally, substrate  114  comprises switching elements (not shown in  FIG. 1 ). In an embodiment, the switching elements can be Thin Film Transistors (TFTs). Further, a driver circuit  130  sends signals related to pixel values to the switching elements. In an embodiment, driver circuit  130  uses low voltage differential signaling (LVDS) drivers. In another embodiment, a transistor-transistor logic (TTL) interface that senses both increase and decrease in voltages is used in driver circuit  130 . Additionally, a timing controller  140  encodes the signals related to pixel values into the signals needed by the diagonal transmissive parts of the pixels. Furthermore, timing controller  140  has a memory to allow self-refresh of the LCD when the signals related to the pixels are removed from timing controller  140 . 
         [0029]    In an embodiment, spacers  118   a  and  118   b  are placed over reflective part  110  to maintain a uniform distance between substrates  114  and  116 . Additionally, pixel  100  comprises first polarizer  120  and second polarizer  122 . In an embodiment, the axes of polarity of first polarizer  120  and second polarizer  122  are perpendicular to each other. In another embodiment, the axes of polarity of first polarizer  120  and second polarizer  122  are parallel to each other. 
         [0030]    Pixel  100  is illuminated by light source  102  or ambient light  124 . The intensity of light passing through pixel  100  is determined by the potential difference between pixel electrode  106 , and common electrode  108 . In an embodiment, liquid crystal material  104  is in a disoriented state and the light passing through first polarizer  120  is blocked by second polarizer  122  when no potential difference is applied between pixel electrode  106 , and common electrode  108 . Liquid crystal material  104  is oriented when the potential difference is applied between pixel electrode  106 , and common electrode  108 . The orientation of liquid crystal material  104  allows the light to pass through second polarizer  122 . 
         [0031]      FIG. 2  illustrates the arrangement of nine pixels  100  of the LCD, in accordance with an embodiment of the present invention. Pixel  100  comprises transmissive part  112   b  and reflective part  110 . In an embodiment, transmissive parts  112   a - c  impart green, blue and red color components respectively to form a color pixel, if the (Red-Blue-Green) RBG color system is followed. Additionally, transmissive parts  112   a - c  can impart different colors such as red, green, blue and white or other color combinations, if other color systems are chosen. Furthermore, transmissive part  113   a  and  114   a  impart green color, transmissive part  113   b  and  114   b  impart blue color, and transmissive part  113   a  and  114   c  impart red color to the color pixel. Additionally, color filters of different thicknesses can be placed over transmissive parts  112   a - c  to decrease or increase the saturation of the color imparted to the color pixel. Saturation is defined as intensity of a specific gradation of color within the visible spectrum. Further, a colorless filter  202   d  can be placed over reflective part  110 . In various embodiments, the thickness of colorless filter  202   d  can vary from zero to the thickness of other color filters placed over transmissive parts  112   a - c . In an embodiment, transmissive parts  112   a  represent a diagonal strip of one of the three colors of the color pixel. Similarly, transmissive parts  112   b  and  112   c  represent a diagonal strip of other two colors of the color pixel. The diagonal strips are used so that the resolution in the color transmissive mode can be close to the resolution in the monochrome (black and white) reflective mode. The resolution in color transmissive mode is high because the human visual system can detect horizontal and vertical lines while visualizing images. In another embodiment, vertical stripes of color can be used that change the resolution more in the horizontal direction and less in the vertical direction when compared to the use of diagonal stripes. The amount of light from light source  102  transmitting through each of the transmissive parts  112   a - c  is determined by the switching elements (not shown in  FIG. 2 ). The amount of light transmitting through each transmissive parts  112   a - c , in turn, determines the color of the color pixel. Further, the shape of transmissive parts  112   a - c  and the color filters can be hexagonal, rectangular, octagonal, circular or so forth. Additionally, the shape of reflective part  110  can be rectangular, circular, octagonal, and the like. Further, reflective part  110  blocks light delivered to diagonal stripes from transmitting to pixels of different colors, for example reflective part  110  blocks light along transmissive parts  112   c  and  113   c  from entering to transmissive parts  112   b  or  112   a . Alternatively, a black matrix mask  203 , a covering between pixels and light sensitive areas of pixels, can be used. In an embodiment, black matrix mask  203  is eliminated to improve the reflectivity of the pixels. 
         [0032]      FIG. 3  illustrates the functioning of pixel  100  in the monochrome reflective mode. Since the monochrome reflective embodiment is explained with reference to  FIG. 3 , only reflective part  110  is shown in the figure. Pixel  100  can be used in the monochrome reflective mode in the presence of an external source of light. In an embodiment, ambient light  124  passes through colorless filter  202   d , and liquid crystal material  104  and is incident on reflective part  110 . Colorless filter  202   d  is used to maintain the attenuation and the path difference of ambient light  124  the same as the attenuation and the path difference of the light in the color transmissive mode. The colorless color filter  202   d  can also be omitted by modifying the design. Reflective part  110  of pixel  100  reflects ambient light  124  to substrate  116 . In an embodiment, a potential difference (v) is applied to pixel electrode  106 , which is electronically coupled to the reflective part  110  and common electrode  108 . Liquid crystal material  104  is oriented, depending on the potential difference (v). Consequently, the orientation of liquid crystal material  104  rotates the plane of ambient light  124 , allowing the light to pass through second polarizer  122 . The degree of orientation of liquid crystal material  104  therefore determines the brightness of pixel  100  and consequently, the luminance of pixel  100 . 
         [0033]    In an embodiment, a normally white liquid crystal embodiment can be employed in pixel  100 . In this embodiment, axes of first polarizer  120  and second polarizer  122  are parallel to each other. The maximum threshold voltage is applied across pixel electrode  106 , and common electrode  108  to block the light reflected by reflective part  110 . Pixel  100  therefore appears black. Alternatively, a normally black liquid crystal embodiment can be used. In this embodiment, axes of first polarizer  120  and second polarizer  122  are perpendicular to each other. The maximum threshold voltage is applied across pixel electrode  106 , and common electrode  108  to illuminate pixel  100 . 
         [0034]      FIG. 4  illustrates the functioning of the LCD in the color transmissive mode by using a partial color filtered approach. Since the color transmissive embodiment is being explained, only transmissive parts of the pixel:  112   a - c  are shown in  FIG. 4 . On substrate  116 , color filters  404   a ,  404   b  and  404   c  are respectively placed in transmissive pixel parts  112   a ,  112   b  and  112   c , as shown in  FIG. 4 . Pixel parts  112   a ,  112   b  and  112   c  refer to the pixel optical value. Part  112   a  has optical contributions from part  102 ,  402 ,  120 ,  114 ,  106   a ,  104 ,  404   a    108 ,  116  and  122 . Part  112   b  has optical contributions from part  102 ,  402 ,  120 ,  114 ,  106   b ,  104 ,  404   b ,  108 ,  116 , and  122 . Part  112   c  has optical contributions from part  102 ,  402 .  120 ,  114 ,  106   c ,  104 ,  404   c ,  108 ,  116 , and  122 . Color filters  404   a ,  404   b , and  404   c  are also spread partially over the reflective area of the pixel. In various embodiments, the color filters cover any amount that is less than half the reflective area of the pixel (e.g., 1% to 50% of the area) and in one particular embodiment the color filters cover about 14% to 18% of the area. Light source  102  is a standard backlight source. Light  402  from light source  102  can be collimated by using a collimating light guide or lens. In an embodiment, light  402 , coming from light source  102 , is passed through first polarizer  120 . This aligns the plane of light  402  in a particular plane. In an embodiment, the plane of light  402  is aligned in the horizontal direction. Additionally, second polarizer  122  has an axis of polarization in the vertical direction. Transmissive parts  112   a - c  transmit light  402 . In an embodiment, each of transmissive parts  112   a - c  has an individual switching element. The switching element controls the intensity of light  402  passing through the corresponding transmissive part. Further, light  402 , after transmitting through transmissive parts  112   a - c , passes through liquid crystal material  104 . Transmissive parts  112   a ,  112   b , and  112   c  are provided with pixel electrodes  106   a - c  respectively. The potential differences applied between pixel electrode  106   a - c , and common electrode  108  determine the orientation of liquid crystal material  104 . The orientation of liquid crystal material  104 , in turn, determines the intensity of light  402  incident on each color filter  404   a - c.    
         [0035]    In an embodiment, a green color filter  404   a  is placed mostly or completely over transmissive part  112   a  and partially the reflective portion  110  (shown in  FIGS. 2 and 3 ), a blue color filter  404   b  is placed mostly or completely over transmissive part  112   b  and partially over the reflective portion  110  (shown in  FIGS. 2 and 3 ) and a red color filter  404   c  is placed mostly or completely over transmissive part  112   c  and partially over the reflective part  110  (shown in  FIGS. 2 and 3 ). Each of color filters  404   a - c  imparts the corresponding color to the color pixel. The colors imparted by color filters  404   a - c  determine the chrominance value of the color pixel. Chrominance contains the color information such as hue and saturation for a pixel. Further, if there is ambient light  124 , the light reflected by reflective part  110  (shown in  FIGS. 2 and 3 ) provides luminance to the color pixel and imparts a monochrome adjustment to the white reflectance of the pixel which can compensate for the greenish look of the LC mode. This luminance therefore increases the resolution in the color transmissive mode. Luminance is a measure of the brightness of a pixel. 
         [0036]      FIG. 5  illustrates the functioning of the LCD in the color transmissive mode by using a hybrid field sequential approach, in accordance with various embodiments. Since the color transmissive embodiment is being explained, only transmissive parts  112   a - c  are shown in  FIG. 5 . In an embodiment, light source  102  comprises strips of LEDs such as LED group 1, LED group 2 and so on (not shown). In an embodiment, the LEDs that are arranged horizontally are grouped together, one LED group below the other, to illuminate the LCD. Alternatively, the LEDs that are arranged vertically can be grouped. The LEDs groups are illuminated in a sequential manner. The frequency of illumination of an LED group can be between 30 frames to 540 frames per second. In an embodiment, each LED group comprises red LEDs  506   a , white LEDs  506   b  and blue LEDs  506   c . Further, red LEDs  506   a  and white LEDs  506   b  of LED group 1 are on from time t=0 to t=5 and red LEDs  506   a  and white LEDs  506   b  of LED group 2 are on from time t=1 to t=6. Similarly, all the red and white LEDs of other LED groups function in a sequential manner. In an embodiment, each LED group illuminates a horizontal row of pixels of the LCD, in case the LED groups are arranged vertically. Similarly blue LEDs  506   c  and white LEDs  506   b  of LED group 1 are on from time t=5 to t=10, and blue LEDs  506   c  and white LEDs  506   b  of LED group 2 are on from time t=6 to t=11. Similarly, all the blue and white LEDs of other LED groups are on in a sequential manner. Red LEDs  506   a , white LEDs  506   b  and blue LEDs  506   b  are arranged so that red LEDs  506   a  and blue LEDs  506   b  illuminate transmissive parts  112   a  and  112   c  and white LEDs  506   b  illuminate transmissive part  112   b . In another embodiment, the LED groups may comprise red, green and blue LEDs. Red, green and blue LEDs are so arranged that green LEDs illuminate transmissive part  112   b  and red and blue LEDs illuminate transmissive parts  112   a  and  112   c , respectively. 
         [0037]    In an embodiment, light  502  from light source  102  is passed through first polarizer  120 . First polarizer  120  aligns the plane of light  502  in a particular plane. In an embodiment, the plane of light  502  is aligned in a horizontal direction. Additionally, second polarizer  122  has the axis of polarization in the vertical direction. Transmissive parts  112   a - c  transmit light  502 . In an embodiment, each of transmissive parts  112   a - c  has an individual switching element. Further, switching elements control the intensity of light passing through each of transmissive parts  112   a - c , thereby controlling the intensity of the color component. Further, light  502 , after passing through transmissive parts  112   a - c , passes through liquid crystal material  104 . Each of transmissive parts  112   a - c  has its own pixel electrode  106   a - c  respectively. The potential differences applied between pixel electrodes  106   a - c , and common electrode  108  determines the orientation of liquid crystal material  104 . In the embodiment in which red, white, and blue LEDs are used, the orientation of liquid crystal material  104 , in turn, determines the intensity of light  502  incident on a green color filter  504 , and transparent spacers  508   a  and  508   b . The intensity of light  502  passing though green filter  504 , and transparent spacers  508   a  and  508   b  determines the chrominance value of the color pixel. In an embodiment, green color filter  504 , is placed corresponding to transmissive part  112   b . Transmissive part  112   a  and  112   c  do not have a color filter. Alternatively, transmissive parts  112   a  and  112   c  can use transparent spacers  508   a  and  508   b  respectively. Green color filter  504 , transparent spacers  508   a  and  508   b  are located on substrate  116 . In another embodiment, magenta color filters can be placed over transparent spacers  508   a  and  508   b . In an embodiment, during time t=0 to t=5, when red LED  506   a  and white LED  506   b  are on, transmissive parts  112   a  and  112   c  are red and green filter  504  imparts a green color to transmissive part  112   b . Similarly, during time t=6 to t=11, when blue LED  506   c  and white LEDs  506   b  are on, transmissive parts  112   a  and  112   c  are blue, and green filter  504  imparts a green color to transmissive part  112   b . The color imparted to the color pixel is formed by the combination of colors from transmissive parts  112   a - c . Further, if ambient light  124  is available, the light reflected by reflective part  110  (shown in  FIGS. 2 and 3 ) provides luminance to the color pixel. This luminance therefore increases the resolution in the color transmissive mode. 
         [0038]      FIG. 6  illustrates the functioning of the LCD in the color transmissive mode by using a diffractive approach. Since the color transmissive embodiment is being explained, only transmissive parts  112   a - c  are shown in  FIG. 6 . Light source  102  can be a standard backlight source. In an embodiment, light  602  from light source  102  is split into a green component  602   a , a blue component  602   b  and a red component  602   c  by using a diffraction grating  604 . Alternatively, light  602  can be split into a spectrum of colors with a different part of the spectrum going through each of transmissive parts  112   a - c  using a micro-optical structure. In an embodiment, the micro-optical structure is a flat film optical structure with small lensets that can be stamped or imparted into the film. Green component  602   a , blue component  602   b  and red component  602   c  are directed to transmissive parts  112   a ,  112   b  and  112   c , respectively, using diffraction grating  604 . Further, the components of light  602  are passed through first polarizer  120 . This aligns the plane of light components  602   a - c  in a particular plane. In an embodiment, the plane of light components  602   a - c  is aligned in the horizontal direction. Additionally, second polarizer  122  has its axis of polarization in the vertical direction. Transmissive parts  112   a - c  allow light components  602   a - c  to be transmitted through them. In an embodiment, each of transmissive parts  112   a - c  has an individual switching element. Switching elements control the intensity of light passing through each of transmissive parts  112   a - c , thereby controlling the intensity of the color component. Further, light components  602   a - c , after passing through transmissive parts  112   a - c , passes through liquid crystal material  104 . Transmissive parts  112   a ,  112   b  and  112   c  respectively have pixel electrodes  106   a ,  106   b  and  106   c . The potential differences applied between pixel electrodes  106   a - c , and common electrode  108  determines the orientation of liquid crystal material  104 . The orientation of liquid crystal material  104 , in turn, determines the intensity of light components  602   a - c  passing through second polarizer  122 . The intensity of color components passing through second polarizer  122  in turn decides the chrominance of the color pixel. Further, if ambient light is available, the light reflected by reflective part  110  (shown in  FIGS. 2 and 3 ) provides luminance to the color pixel. This luminance therefore increases the resolution in the color transmissive mode. 
         [0039]    As presented herein, transmissive part of the pixel is arranged diagonally rather than vertically or horizontally, as in the case of prior known LCDs. The diagonal arrangement of the transmissive part increases the resolution, as compared to prior known LCDs and therefore provides a better display. 
         [0040]    Additionally, the presence of ambient light enhances the luminance of the color pixel in the color transmissive mode. Therefore, each pixel has both luminance and chrominance. This increases the resolution of the LCD. Consequently, the number of pixels required for a particular resolution is lower than in prior known LCDs, thereby decreasing the power consumption of the LCD. Further, a Transistor-Transistor Logic (TTL) based interface can be used that lowers the power consumption of the LCD as compared to the power consumed by the interfaces used in prior known LCDs. Additionally, because the timing controller stores the signals related to pixel values, the LCD is optimized for using the self refresh property, thereby decreasing the power consumption. In various embodiments, thinner color filters which transmit less saturated color and more light can be used. Hence, various embodiments facilitate the process of reducing the power consumption, as compared to prior known LCDs. 
         [0041]    Further, in an embodiment (described in  FIG. 5 ), green or white color light is always visible on pixel  100 , and only the red and blue color lights are switched. Therefore, a lower frame rate is required as compared to the frame rate of prior known field sequential displays. 
         [0042]    While the preferred embodiments of the invention have been illustrated and described, it will be clear that the invention is not limited to these embodiments only. Numerous modifications, changes, variations, substitutions and equivalents will be apparent to those skilled in the art without departing from the spirit and scope of the invention, as described in the claims.