Abstract:
The present invention relates to a liquid crystal display, more specifically, relates to a full color cholesteric display employing circularly polarized micro-color filter which is composed of polymeric cholesteric thin film. The display has a long time memory and excellent characteristics of brightness and contrast. A built-in cholesteric color filter structure provides a full color gamut of circular polarization. A cholesteric liquid crystal cell structure, as a circular polarization modulator, provides optical ON and OFF states respectively with its one texture as a circular polarizer and the other texture as a depolarizer. Both of those two textures are electric field controllable.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to a liquid crystal display, more specifically, relates to a reflective full color cholesteric display employing reflective circularly polarizing micro-color filter which is composed of polymeric cholesteric thin film. The display has a long time memory and an excellent characteristics of brightness and contrast.  
         BACKGROUND OF THE INVENTION  
         [0002]    Liquid crystal display devices comprising polarizers and micro-color filter components are utilized in various flat panel displays. Reflective displays with full color capability are currently top-of-the-line products for portable electronics. Such reflective full color performance meets its basic requirement of high-information-content displays for a simple reason of less power consumption and thinner structure compared with the backlit counterparts. The typical reflective displays, nowadays, are reflective thin film transistor (TFT) display and reflective STN display. However, the overall performances of the reflective displays are still not as good as the transmissive backlit mode in terms of brightness, contrast ratio and viewing angle. And it is difficult to achieve the same contrast practically available for a transmission backlit display. These disadvantages result mainly from light-loss by the absorptive polarizers and from the angular dependency of the axis of polarization. In general, there is more than 60% optical loss. In the case of color display, light-loss is further aggravated due to the absorptive color filter which will cut off at least 60% incoming light. Current full color display is achieved by micro-color filter element made by organic dye or pigment which involves multiple patterning manufacturing process. It will take more challenge to produce the reflective color filter than that of the transmissive one.  
           [0003]    U.S. Pat. No. 4,032,218 introduces a cholesteric color reflector and TN cell to display monochrome information on the black background. A quarter-wave plate is positioned between the cholesteric film and the TN display to convert circular polarization into linear polarization. A black coating is attached on the back of the device to absorb all the residual light passing from the cholesteric film. As a result, a viewer will sense a bright color light generated by the cholesteric color film on a black background.  
           [0004]    U.S. Pat. No. 5,555,114 teaches cholesteric color selection layer, which selectively reflecting circularly polarized light of a specific wavelength and an optical layer formed on the color selection layer and having a liquid crystal and means for applying an electric field to the liquid crystal layer. A linear optical shifting layer on the top of cholesteric color filter convert circularly polarized light into linear polarization. This approach is not sufficient for a STN cell, a non-wave-guiding mode display, because of its non-linear optical performance due to the super twist dispersion to the incoming light The color is actually the combination of color dispersion of birefringence of display cell and Bragg reflection from cholesteric color selection layer In order to eliminate the color dispersion, the different voltage will apply to the different color pixels to convert the elliptical polarization into circular polarization, yet this make driving scheme very complicate or even impracticable.  
           [0005]    U.S. Pat. No. 5,949,513 teaches a method of manufacturing a multi-color cholesteric display. The method include the steps of (1) deposition a twist agent on a first substrate, the twist agent becoming an in situ twist agent, (2) bringing a second substrate into proximity with the first substrate to form at least one interstitial region between the second and first substrates, (3) introducing liquid crystal having an initial pitch into the at least one interstitial region proximate the in situ twist agent and (4) stimulating the LC and the in situ twist agent to cause the LC and the in situ twist agent to mix in situ, the in situ twist agent to mix in situ, the in situ twist agent changing the initial pitch of the LC. A permanent polymer wall is necessary to isolate the LC of different pitch from flowing around. It is difficult to make defect-free product Furthermore, the color cholesteric display has different threshold voltage of each color due to the pitch difference which makes the driving very complicated.  
         SUMMARY OF THE INVENTION  
         [0006]    To address the above-mentioned deficiencies of the prior art, it is a primary object of the present invention to provide a full color reflective cholesteric display while maintaining the cholesteric display&#39;s superiority such as high environmental contrast ratio, hemispheric viewing angle, zero-field long time memory and so on.  
           [0007]    It is another object of the present invention to provide the cholesteric liquid crystal cell structure as a circular polarization modulator, i.e., with its one texture as a circular polarizer and the other texture as a depolarizer. Both of those two textures are electric field controllable.  
           [0008]    It is a further object of the present invention to provide a built-in cholesteric color filter with highly saturated circularly polarized color covering the whole visible wavelength. The cholesteric liquid crystal cell structure allows such a cholesteric film to be the coloring elements to reproduce a vivid image or displayable information.  
           [0009]    It is again another object of the present invention to provide an ultra-thin cholesteric coloring element positioned on the top of the conductive patterning and inside the display cell, thus simplifies the display manufacturing process.  
           [0010]    It is still a further object of the present invention to provide a transflective cholesteric color filter structure, which is capable of reflecting a full gamut visible circular polarization with one polarity and of transmitting a full gamut visible circular polarization with the other polarity.  
           [0011]    It is another object of the present invention to provide a dual-working mode color display. During the day or in a bright ambient light, the display works as a reflective display while during the night or in a dark ambient light condition, the display works as a transmissive backlit display.  
           [0012]    It is again another object of the present invention to provide an overhead color projector with no absorptive polarizing component, which will be able to be used in a normal transparence presentation.  
           [0013]    It is a further object of the present invention to provide an ultra-compact, power-saving portable color projector without any dichroic and absorptive components.  
           [0014]    It is still another object of the present invention to provide a circular polarizer on the top of the display to enhance the color purity and contrast ratio of the display.  
           [0015]    It is still a further object of the present invention to provide an optical compensation solution to the color shift of the cholesteric color filter by means of the infrared Bragg reflection of controllable cholesteric cell structure.  
           [0016]    It is the final object of the present invention to provide a manufacturing process to produce a built-in cholesteric color filter in a mass production scale.  
           [0017]    In the attainment of the above-described objects, the present invention provides a essential display cell structure including two cholesteric layers: (1) cholesteric light shutter which generates optical “on” state and optical “off” state; (2) cholesteric coloring element which generates R, G and B primary colors for the display shutter. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]    [0018]FIG. 1 illustrates a schematic reflective display structure and its light reflective behavior.  
         [0019]    [0019]FIG. 2 illustrates another schematic reflective display structure and its light behavior.  
         [0020]    [0020]FIG. 3 illustrates a schematic sectional drawing of the full color cholesteric display.  
         [0021]    [0021]FIG. 4 illustrates another schematic sectional drawing of the full color cholesteric display.  
         [0022]    [0022]FIG. 5 illustrates a front light and back light dual-working mode full color display.  
         [0023]    [0023]FIG. 6 illustrates a display mode without utilizing circular polarizer.  
         [0024]    [0024]FIG. 7 illustrates a full color CLC projection display.  
         [0025]    [0025]FIG. 8 illustrates a schematic drawing of a color CLC portable projector.  
         [0026]    [0026]FIG. 9 illustrates a schematic drawing of CCF manufacturing process.  
         [0027]    [0027]FIG. 10 illustrates a schematic drawing of another CCF manufacturing process.  
     
    
     DETAILED DESCRIPTION  
       [0028]    Referring first to FIG. 1, illustrated is the schematic reflective display structure and its light reflective behavior. A cholesteric cell structure  110  includes a controllable planar texture  111  and controllable focal conic texture  112 . A circular polarizer plate  120  locates above the cholesteric cell structure, which may or may not directly touch to it. A cholesteric micro color filter  130  directly attaches to the cholesteric cell structure. The optical handedness of those components  110 ,  120  and  130  are arranged in such a way that the cholesteric cell structure  110  has opposite handedness to the circular polarizer (CP)  120 , and to the cholesteric color filter (CCF) while the CCF has the same handedness as the CP. For example, if the CP and the CCF are chosen as right-handed (RH) then the cholesteric cell structure will be containing left-handed (LH) cholesteric liquid crystal (CLC) material.  
         [0029]    The CLC material in controllable planar texture has an intrinsic visible wave bend  152  due to Bragg reflection. However, the intrinsic reflection will be cut off completely by the opposite-handed front CP  120 . In other words, the color from the cholesteric cell structure is non-displayable. On the contrary, the Bragg reflections  151  from the polymeric CCF layer will penetrate all the way through the cholesteric cell and through the front CP without substantial attenuation, and then emerge towards an observer as vivid bright colors  153 .  
         [0030]    The light path in display&#39;s planar texture can be described as follows: The incoming light ray  140  passing through the front CP  120  becomes RH polarized light  141  with the intensity less than half of the origin. Because of its opposite handedness, light  141  further passing through CLC&#39;s planar texture becomes light  142  without substantially changing its polarity and intensity. When light  142  reaches to CCF, it will be Bragg reflected by each individual red  133 , green  131  and blue  132  sub-pixel, and becomes color light  143 . All the non-reflected light wave bend will be absorbed by the black coating  134  on the back side of the CCF. The color light  143  then passes through the CLC planar texture (see light  144 ) and CP, and finally becomes out-coming linear polarization  145 .  
         [0031]    On the other hand, when the light  141  hits on the CLC&#39;s focal conic texture, it will substantially become depolarized light  146 . All those lights, including newly generated LH component and non-selective reflected RH wave bend, will pass through the CCF and be absorbed by the black coating  134  on the back side of the CCF. Only a small portion of the selected RH light  147  will be bounced back and depolarized again in the CLC&#39;s focal conic texture (see light  148 ). The depolarized light  148  then passes through the front CP with the cost of more than 50% loss. Note that the scattering effect in CLC&#39;s focal conic texture not only depolarizes the light but changes the light direction as well. The remaining light will be further attenuated by the interfacial surface-reflection. As a result, only less than 2% of the total incoming light has a chance to reach back in the CLC&#39;s focal conic texture area.  
         [0032]    In terms of contrast ratio, assuming the CP has 45% transmission, then the maximum reflectivity in planar texture will be 15%; and maximum reflectivity in focal conic texture will be 2%. Those skilled in the art create a full color reflective display with contrast ratio 7:1 if the surface reflection is properly taken care of.  
         [0033]    Turning now to FIG. 2., illustrated is another schematic reflective display structure and its light behavior. A cholesteric cell structure  210  includes a controllable planar texture  211  and controllable focal conic texture  212 . A circular polarizer plate  120  locates above the cholesteric cell structure, which may or may not directly touch to it A cholesteric micro color filter  130  directly attaches to the cholesteric cell structure. The handedness of those component  210 ,  120  and  130  are arranged in such a way that the cholesteric cell structure  210  has the same handedness as both the CCF and CP. For example, all the components  120 , 210  and  130  have the right-handed polarity. The CLC material in controllable planar texture has an intrinsic invisible wave bend when illuminated and viewed almost vertical to the display surface. But it may become visible when viewed or illuminated aberrant to the normal direction. The central Bragg reflection wavelength is chosen in an infrared wave bend, for example, 700˜1500 nm, more preferably, 750˜850 nm. The out-coming wave-bend  253  will be a composition of a visible wave bend  151  from CCF and an invisible wave bend  252  from CLC&#39;s planar texture.  
         [0034]    The light path in display&#39;s planar texture can be described as follows: The incoming light ray  140  passing through the front CP  120  becomes RH polarized light  141  with the intensity less than half of the origin. Light  141  further passing through CLC&#39;s planar texture becomes light  242  without substantially changing its polarity and intensity. When light  242  reaches to CCF, it will be Bragg reflected by each individual red  133 , green  131  and blue  132  sub-pixel, and becomes color light  243 . All the non-reflected light wave bend will be absorbed by the black coating  134  on the back side of the CCF. The color light  243  then passes through the CLC planar texture (see light  244 ) and CP  120 , and finally becomes out-coming linear polarization  245 .  
         [0035]    On the other hand, when the light  141  hits on the CLC&#39;s focal conic texture, it will substantially become depolarized light  246 . All those lights, including newly generated LH component and non-selective reflected RH wave bend, will pass through the CCF  130  and be absorbed by the black coating  134  on the back side of the CCF  130 . Only a small portion of the selected RH light  247  will be bounced back and depolarized again in the CLC&#39;s focal conic texture (see light  248 ). The depolarized light  248  then passes through the front CP  120  with the cost of more than 50% loss. Note that the scattering effect in CLC&#39;s focal conic texture not only depolarizes the light but changes the light direction as well. The remaining light will be further attenuated by the interfacial surface-reflection. As a result, only less than 2% of the total incoming light has a chance to reach back in the CLC&#39;s focal conic texture area.  
         [0036]    The advantage of utilization of CLC&#39;s near infrared reflection is that, to a certain extent, it compensates the color shift when it is viewed or illuminated at a oblique angle and enhances red color saturation of CCF. In the field of cholesteric color filter technology, there are two fundamental problems regarding the optical performances. Firstly, angular color dispersion due to the fact that the wavelength (λ) of the Bragg reflection has dependency to the viewing angle (θ),  
         λ=n p cos θ 
         [0037]    where “n” represents the average refractive index and “p” the pitch of CLC material. When the light is illuminating at a normal angle to the display surface but it is viewed from an oblique angle θ, the wavelength λ will be getting smaller. This is so called short-wavelength-color shift. Secondly, the brightness of red color is always not as good as the green and blue one due to the less twisting power of cholesteric domains in the red region. The addition of the infrared color from CLC&#39;s planar texture will not only be able to enhance the brightness of the display but also to maintain the neutral color-reproduction reproduction when viewed at an oblique direction. The latter, obviously enlarges viewing angles of the display.  
         [0038]    There is another color dispersion, temperature induced color change in the prior art cholesteric technology This is a common issue in U.S. Pat. No. 5,949,513 and U.S. Pat. No. 6,285,434 where the R.G.B colors are directly generated from the controllable CLC planar texture. Those skilled in the art, however, generates them from polymeric cholesteric coloring film. The color of CCF has already been locked up after polymerization during a manufacturing process. The CLC planar texture, now, becomes a circularly polarized light modulator of the cholesteric color filter.  
         [0039]    Turning now to FIG. 3, illustrated is a schematic sectional drawing of the full color cholesteric display. It consists of a display cell  310 , a front circular polarizer (CP)  120  and a CCF  130 . The cell  310  is a basic structure of liquid crystal display, where a CLC material with controllable planar texture  311  and controllable focal conic texture  312  are sandwiched between two patterned conductive substrates  314  and  315  (either glass or plastic), and isolated by a polymeric ring  316 . The cell gap, which is predetermined by a spacer material, micro-balls or bars, is in the range of 1 to 10 micrometers A thin polymer layer may be coated onto the inside of surfaces of the substrates to align the liquid crystal molecules in a specific way An electronic waveform  360  needs to connect to the conductive lead of the cell. The transparent conductive ITO patterning  315  is structured on the top of the CCF layer  130 . Because of the intrinsic stability of the cholesteric focal-conic texture and planar texture, no further alignment layer is necessary on bottom ITO patterning, and the CLC material will directly contact with the conductive ITO electrodes  315 . A black coating layer  317  is attached on the back of the display structure.  
         [0040]    The light path in display&#39;s planar texture can be described as follows: The incoming light ray  340  passing through the front CP  120  becomes RH polarized light  341  with the intensity less than half of the origin. Light  341  further passes through CLC&#39;s planar texture without substantially changing its polarity and intensity. When light  341  reaches to CCF, it will be Bragg reflected by each individual red  133 , green  131  and blue  132  sub-pixel, and becomes color light  343 . All the non-reflected light  342  will be absorbed by the black coating  317  on the back side of the display. The color light  343  then passes through the CLC planar texture and CP  120 , and finally becomes out-coming linear polarization  345 .  
         [0041]    On the other hand, when the light  341  hits on the CLC&#39;s focal conic texture, it will substantially become depolarized light  346 . All those lights, including newly generated LH component and non-selective reflected RH wave bend  349 , will pass through the CCF  130  and be absorbed by the black coating  317  on the back side of the display. Only a small portion of the selected RH light  348  will be bounced back and depolarized again in the CLC&#39;s focal conic texture. The depolarized light then passes through the front CP  120  with the cost of more than 50% loss. Note that the scattering effect in CLC&#39;s focal conic texture not only depolarizes the light but changes the light direction as well. The remaining light will be further attenuated by the interfacial surface-reflection. As a result, only less than 2% of the total incoming light has a chance to reach back in the CLC&#39;s focal conic texture area.  
         [0042]    Turning now to FIG. 4, illustrated is another schematic sectional drawing of the full color cholesteric display. It consists of a display cell  410 , a front circular polarizer (CP)  120  and a CCF  130 . The cell  410  is a basic structure of liquid crystal display, where a CLC material with controllable planar texture  411  and a controllable focal conic texture  412  are sandwiched between two patterned conductive substrates  414  and  415  (either glass or plastic), and isolated by a polymeric ring  416 . The cell gap, which is predetermined by a spacer material, micro-balls or bars, is in the range of 1 to 10 micrometers A thin polymer layer may be coated onto the inside of surfaces of the substrates to align the liquid crystal molecules in a specific way. An electronic waveform  360  needs to connect to the conductive lead of the cell. The transparent conductive ITO patterning  415  is structured underneath of the CCF layer  130 . Because of the intrinsic stability of the cholesteric focal-conic texture and planar texture, no further alignment layer is necessary, and the CLC material will directly contact with the CCF layer  130 . A black coating layer  417  is attached on the back of the display structure.  
         [0043]    The light path in display&#39;s planar texture can be described as follows: The incoming light ray  340  passing through the front CP  120  becomes RH polarized light  341  with the intensity less than half of the origin. Light  341  further passes through CLC&#39;s planar texture without substantially changing its polarity and intensity. When light  341  reaches to CCF, it will be Bragg reflected by each individual red  133 , green  131  and blue  132  sub-pixel, and becomes color light  343 . All the non-reflected light  342  will be absorbed by the black coating  417  on the back side of the display. The color light  343  then passes through the CLC planar texture and CP  120 , and finally becomes out-coming linear polarization  345 .  
         [0044]    On the other hand, when the light  341  hits on the CLC&#39;s focal conic texture, it will substantially become depolarized light  346  All those lights, including newly generated LH component and non-selective reflected RH wave bend  349 , will pass through the CCF  130  and be absorbed by the black coating  417  on the backside of the display. Only a small portion of the selected RH light  348  will be bounced back and depolarized again in the CLC&#39;s focal conic texture. The depolarized light then passes through the front CP  120  with the cost of more than 50% loss. Note that the scattering effect in CLC&#39;s focal conic texture not only depolarizes the light but changes the light direction as well The remaining light will be further attenuated by the interfacial surface-reflection. As a result, only less than 2% of the total incoming Light has a chance to reach back in the CLC&#39;s focal conic texture area.  
         [0045]    The difference from FIG. 3 is that the CCF  130  is deposited on the top of the transparent conductive layer, which makes the manufacture process much simpler The color filter is designed in the range of 1.2˜3μ, more preferably 1.5˜2.0μ.  
                                                                             R   G   B                                        λ 0     650   550   450           n   1.5   1.5   1.5           P   0.43   0.37   0.3           D/P   3   3.2   4                      
 
         [0046]    The average reflectivity for blue will reach 95% of the heoretical data while the red will reach approximately 80% of the theoretical data.  
         [0047]    In this case, red color compensation from the CLC planar texture is necessary. The increasing of driving voltage due to the voltage drop of CCF can be compensated to a certain extent by the infrared cholesteric cell structure. It is practical to use normal STN driver with the working voltage of 42V.  
         [0048]    If the thickness of CCF  130  is designed at 2.0μ, the DIP value then will become Red 4.65, Green 6.6. Now, Green and Blue have been reached to their theoretical saturation and Red color will also get to the 98% of maximum reflectivity. Considering the voltage drop of CCF, the CLC cell thickness should be less than 3μ and the intrinsic pitch of CLC should be in the infrared wavelength, for example, 850 nm The actual driving voltage will be then less than 50 volts, which is within the scope of a normal design of CMOS driver ICs.  
         [0049]    Turning now to FIG. 5, illustrated is a dual-working mode full color display. During the daytime, the display, as depicted in FIG. 5A, is similar to FIG. 2 in terms of optic “on” and optic “off” states. What is different from FIG. 2 is that we add liquid crystal dyes in the cholesteric liquid crystal color filter cells. For example, a red dye is added in the reflective red color cell, green dye in reflective green color, and blue dye in the reflective blue color cell correspondingly. The concentration of the dichroic dye in CCF is normally in the range of 1˜3%. The addition of red dye to the cholesteric color filter ensures red light reflection and transmission while cutting off the rest visible light, i.e. “green” and “blue” light. Similarly, the addition of green dye to the cholesteric color filter ensures green light reflection or transmission while cutting off the red and blue light. So does the blue dye. Therefore, the dual-purpose color filter, in the present invention, can be used for either reflective full color display or transmissive full color display.  
         [0050]    A cholesteric cell structure  210  includes a controllable planar texture  211  and controllable focal conic texture  212 . A circular polarizer plate  120  locates above the cholesteric cell structure, which may or may not directly touch to it. A cholesteric micro color filter  130  directly attaches to the cholesteric cell structure. The handedness of those component  210 ,  120  and  130  are arranged in such a way that the cholesteric cell structure  210  has the same handedness as both the CCF and CP. For example, all the components  120 ,  210  and  130  have the right-handed polarity. The CLC material in controllable planar texture has an intrinsic invisible wave bend when illuminated and viewed almost vertical to the display surface. But it may become visible when viewed or illuminated aberrant to the normal direction The central Bragg reflection wavelength is chosen in an infrared wave bend, for example, 700˜1500 nm, more preferably, 750˜850 nm. The out-coming wave-bend  253  will be a composition of a visible wave bend  151  from CCF and an invisible wave bend  252  from CLC&#39;s planar texture.  
         [0051]    The light path in display&#39;s planar texture can be described as follows. The incoming light ray  140  passing through the front CP  120  becomes RH polarized light  141  with the intensity less than half of the origin. Light  141  further passing through CLC&#39;s planar texture becomes light  242  without substantially changing its polarity and intensity. When light  242  reaches to CCF, it will be Bragg reflected by each individual red  133 , green  131  and blue  132  sub-pixel, and becomes color light  243 . All the non-reflected light wave bend will be absorbed by the dark room between the CCF  130  and backlit panel  570 . The color light  243  then passes through the CLC planar texture (see light  244 ) and CP  120 , and finally becomes out-coming linear polarization  245 .  
         [0052]    On the other hand, when the light  141  hits on the CLC&#39;s focal conic texture, it will substantially become depolarized light  246  All those lights, including newly generated LH component and non-selective reflected RH wave bend, will pass through the CCF  130  and be absorbed by the dark room between the CCF  130  and back-lit panel  570 . Only a small portion of the selected RH light  247  will be bounced back and depolarized again in the CLC&#39;s focal conic texture (see light  248 ). The depolarized light  248  then passes through the front CP  120  with the cost of more than 50% loss. Note that the scattering effect in CLC&#39;s focal conic texture not only depolarizes the light but changes the light direction as well. The remaining light will be further attenuated by the interfacial surface-reflection. As a result, only less than 2% of the total incoming light has a chance to reach back in the CLC&#39;s focal conic texture area.  
         [0053]    [0053]FIG. 5B shows schematic principle of a transmissive full color display. When the black-lit  570  is in “on” state, neutral light  541  from the light-guide plate passing through color filter  130  becomes left-handed color light  542 . Three primary colors, red, green and blue, are generated from the corresponding red, green and blue color microstructure. The light  542  proceed passing through the CLC&#39;s planar texture without changing its polarity (LH) and amplitude (see  543 ), and finally extinct by the RH front circular polarizer. The display is in optic “off” state.  
         [0054]    On the other hand, when light  542  passing through the CLC&#39;s focal-conic texture, it becomes depolarized color light  544 . However, color information determined by the controllable CLC matrix and color filter still remains in the light  544 . Finally, light  544  passing through the front CP  120  becomes emerging light  545 .  
         [0055]    Note that the full color transmissive image is a reverse mode image relative to the reflective mode. The optic “on” state area in the reflective mode becomes now optic “off” state area in the transmissive mode; and the optic “off” state area in the reflective mode becomes now optic “on” state area in the transmissive mode. Unlike the prior art&#39;s pure absorptive color filter, the novel color filter has a light recycle function. The RH light  546  reflected from the CCF hits on the backlit system  570  and becomes depolarized light  547 . Then it moves forward along with light  541 . As a result, the light  545  have a brighter appearance than the prior art.  
         [0056]    Turning now to FIG. 6, illustrated is another CLC display mode without circular polarizer. The CLC material has an intrinsic infrared Bragg reflection. The display is based upon backlit illumination. When a collimated circularly polarized light  640  passes through cholesteric color filter with the same handedness, three primary colors, red, green and blue circularly polarized light  641  are generated respectively. The light  641  further passes through the CLC&#39;s controllable planar texture area, maintaining its polarity and amplitude. Finally a circular polarized light  642  appears at front of the display.  
         [0057]    On the other hand, when the light  641  passes through the CLC&#39;s controllable focal-conic texture area, it will become scattered depolarized light  643 . The above-mentioned two optical states, collimated polarized state and scattered depolarized state, are very useful for projection applications.  
         [0058]    Turning now to FIG. 7, illustrated is a full color CLC projection display  700  employing the principles of the present invention. The full color CLC projection display  700  includes a controllable CLC structure  210  and a cholesteric color filter  130  which located proximate to the controllable CLC cell structure  210  and which has a similar handedness to that of the CLC cell structure. The color filter  130  is a pattern of Bragg reflective yellow, cyan and magenta (“YCM”) region corresponding to individual cells of the controllable CLC structure  210 .  
         [0059]    The operation of the full color CLC projection display  700  is similar to that of the front-lit full color CLC display  200 ; the difference being that the image perceived by a viewer is produced by the light transmitted through the display rather than reflected therefrom. The full color CLC projection display  700  is preferably illuminated by a light source  640 , a circularly polarized white light with the same polarity as the CCF.  
         [0060]    When the collimated circularly polarized  640  pass through CCF, the portion of Bragg reflection including yellow, cyan and magenta will reflect backward, and the red, green and blue, three primary colors will emit forward from the corresponding cell regions. When the CLC  210  is in an “on” state, the light passes through the controllable planar area and it will maintain its polarity and amplitude. The transmitted light  642  is projected by overhead projector  710  onto screen  730  where it is perceived by an observer  780 .  
         [0061]    When the CLC  210  is in an “off” state, the light passed through the controllable focal conic area is optically scattered and depolarized by the CLC  210 . The portion  643  of the forward-scattered light is emitted from the controllable CLC&#39;s focal conic texture at wide angle. The collection angle œof the overhead projector  710 , however, is generally narrow, resulting in only an insubstantial portion of the forward-scattered light  643 , which is projected onto the screen  730 . Thus, for the region of CLC&#39;s focal conic texture of the full color CLC projection display  700 , a substantial portion of the incident light is not perceived by an observer, thus yielding a display with a high contrast ratio.  
         [0062]    What is different from the prior art is that those skilled in the art eliminate the utilization of the absorptive circular polarizer. Thus offers the projection display ultra high brightness and allows the overhead projector to do a traditional transparency presentation when the whole CLC panel is in an “on” state.  
         [0063]    Turning now to FIG. 8, illustrated is a schematic drawing of a color CLC portable projector  800 , employing the principles of the present invention. The color CLC portable projector  800  includes a controllable CLC cell structure  210 , a CCF  130 , a black wall housing  850 , backlit system  640  and projection lens  860 . The operation of the color portable projector is identical to that of the color overhead projector  700 . The only difference is that the addition of the black wall housing  850  provides the integrity of the portable device. The function of black wall housing is to absorb the forward-scattering light emitted from the focal conic texture area of the controllable CLC structure.  
         [0064]    A most advantageous point of such portable projector over the prior art is that there are no any absorptive optical components, such as filter and polarizer which involved in the traditional TFT-TN projectors. The design of non-absorptive CCF filter and non-absorptive CLC light modulator enables the smallest projector with the brightest projection image.  
         [0065]    Brightness is the primary specsmanship measure of a projector. For years “more brightness” has been the goal of manufacturers around the world. More technically, brightness is the consumer term for the luminance in a projected image that is responsible for the highlight area of that image to have a high contrast with the darkest areas. It is almost universally measured in ANSI lumens on the nine-point grid. A projector can never make the dark parts of a project image any blacker than they already are when the project is off, and the ambient room light is on. However, by making the highlights in the image brighter than the contrast ratio still can be impressive. Because of the high brightness, CLC projector can overcome some ambient light to maintain an impressive contrast ratio.  
         [0066]    The other advantage of the CLC portable projector is its superior color purity. In video projections, much more is at stake with accurate color reproduction, color gamut is a primary goal of course. One must be able to accurately reproduce all the colors of real life as accurately as possible for realism. Unfortunately CRT phosphors have limited deep red reproduction, for so long it is now part of our color standards for video reproduction to have a somewhat orange-red displayed in place of deep red. Cholesteric colors, on the other hand, have wider gamut and a larger triangle area in the CIE diagram. This is because of the fact that the cholesteric color is coming from Bragg reflection of the natural light, thus the R.G.B primary colors are the purest ones than any other colorant agents. Therefore, CLC projector gives out almost truthful color reproduction.  
         [0067]    Turning now to FIG. 9, illustrated is a CCF manufacturing-process  900 . The CCF manufacturing process includes the following steps:  
         [0068]    Step 1. Build-Up Fill Channel Structure  910   
         [0069]    The fill channel structure consists of a permanent substrate  911 , a temporary substrate  912  and a polymeric wall material  913 . There are two open channel groups  914  and  915  along the opposite direction of the CCF substrate. There is a non-filling channel group  916  enclosed in the channel structure. The polymeric wall material also works as a spacer that determines the thickness of CCF A programmable ink-jet dispenser is a good tool to construct the wall configuration. The height and width of the wall are usually in the range of 5˜10μ and 15˜25μ, respectively. The polymeric wall material  913  can be UV curable glue which is polymerized under UV exposure machine after the permanent substrate  911  and the temporary substrate  912  have been properly laminated together.  
         [0070]    Step 2. Fill-In The CCF Pre-Polymer Formulation  
         [0071]    The opening channel group  914  is filled with first primary color formulation, for example, red color, under vacuum and cured by a UV beam  930  as soon as the completion of filling. Then, the opening channel group  915  is filled with the second primary color formulation, for example, green color, under the same conditions as the first one, and then cured by UV exposure. The first and the second filling process can be carried out simultaneously at a vacuum filling chamber, and cured afterward at the same chamber.  
         [0072]    The temporary substrate  912  and the permanent substrate  911  also work as alignment layers during the filling process that ensures the CCF formulation aligned in a good planar texture before being polymerized.  
         [0073]    Step 3. Delaminate The Temporary Substrate  
         [0074]    The temporary plastic substrate  912  is delaminated or released from the permanent glass substrate  911 . The polymerized first and the second CCF material is left on the permanent substrate  911  and the third CCF channel  916 , now, is opening to the air.  
         [0075]    Step 4. Laminate Of The Third Primary Color Formulation.  
         [0076]    A laminator  940  carries out the third CCF primary color formulation. A pair of nip rubber rollers  941  and  942  is designed with durability of 45˜50 and adjustable gap control mechanism. The laminator also has a registration and speed control system. A transparent conductive film  921  with ITO layer  922  face up and protective layer  923  attached on the surface of ITO layer  922 . The third primary color formulation is applied to the front edge of the bottom substrate by a linear motion of a dispenser The registered conductive film  921  then is gently touched down to the top of CCF material while moving through the rubber nip of the laminator  940 . The third CCF primary color formulation is spread out between the substrates and filled exactly in the channel  916 . The speed of lamination is set at 0.7˜1 ft/second to remove any possible air bubbles in the channel.  
         [0077]    Step 5. UV Cure The Third Primary Color  
         [0078]    The third primary color, for example, blue color is cured by UV beam  930  under a photo mask  931  ensuring the curing window is corresponding exactly to the channel group  916 . Finally, an overall UV exposure is necessary to cure the remaining uncured monomer above its clearing temperature, at which the material on the top of the channels  914  and  915  will become “color-less” transparent after curing.  
         [0079]    It is also applicable that during the step 3, the delamination can be immediately executed by dispensing the third primary color formulation and laminated again with the same plastic substrate. The masking exposure can be followed once the third primary color formulation has completely filled into the channel  916 . The temporary substrate then is peeled off from the CCF layer. The remaining uncured third primary color material is then cleaned up on a spin cleaner. Finally, a composite film, including ITO conductive film  922  with the thickness in 25˜50μ and a protection liner film  923  with the thickness in 50˜75μ, are laminated on the CCF by an UV-cured adhesive. The protective liner film  923  is disregarded when the ITO substrate is ready for the patterning process. Such alternative process is especially useful for the dual-working mode CLC display introduced in FIG. 5, where a dichroic dye is dissolved into the cholesteric monomer formulation. In this way, there will be no any possible dye residue from the third primary color left on the top of the first and second primary color layer.  
         [0080]    Here comes an example regarding the specifications of the material. The wall material  913  is a black colored material, made of epoxy or polyacrylate. The temporary film is a polyester film with the thickness of 75˜125μ. The ITO coated film is an isotropic polymer film with the thickness of 25˜50μ. And the permanent substrate  911  is a polished glass with the thickness of 0.5˜1.1 mm.  
         [0081]    Turning now to FIG. 10, illustrated is a schematic drawing of another CCF manufacturing process. A cholesteric CCF pre-polymer mixture is made of CLC pre-polymer, chiral nematic LC, polymeric spacer, UV initiator and so on. The viscosity of the mixture is adjusted in the range of 300˜500 CP. The optimal percentage of the spacer material is in the range of 0.15˜0.2%.  
         [0082]    A laminator  940  carries out the application of CCF pre-polymer mixture. A pair of nip rubber rollers  941  and  942  is designed with durability of 45˜50 and adjustable gap control mechanism. The laminator also has a registration and speed control system. The mixture  1010  is applied on the front edge of glass substrate by a linear moving dispenser. The ITO conductive film  921  is laid on the top of CCF material while moving through the rubber nip of the laminator  940 . The CCF pre-polymer mixture is spread out between the two substrates with the thickness determined by the spacer. The color tint of the CCF pre-polymer has a non-linear dependence of temperature because both the pitch and Δn are the variables of temperature. When the sandwiched structure is moved on the heating stage and the temperature is raised incrementally, three primary colors will appear at three-temperature points T 1 , T 2  and T 3 . A photo mask  931  is registered to the first color area on the top of the sandwiched structure and underneath of an UV exposure machine. As the temperature reaches T 1 , the UV exposure machine will be turned “on” and started to expose the window area. The CCF pre-polymer material in the exposed area will become polymerized, thus the first color has been fixed because the mixture in the exposed area has already been out off liquid crystal phase and the pitch has been locked by the CLC polymeric structure. The photo mask  931  then is registered to the second color area. When the temperature is adjusted at T 2 , the UV exposure machine will be turned “on” and started to expose the second window area. Thus the second color has been fixed. The photo mask  931  may or may not be registered to the third color area When the temperature is adjusted at T 3 , the UV exposure machine will be “on” and expose the area thus the third color has been fixed. After the three consecutive exposures, the three primary color arrays will be formed at the CCF layers.  
         [0083]    The ITO conductive layer is then followed by a patterning process in a normal LCD production line until a complete full color CLC display is finished.  
         [0084]    The ITO conductive patterning may also be pre-made on the bottom glass substrate. Now, the top plastic layer becomes a temporary alignment film. After completion of the CCF structure as mentioned above, the top plastic layer can be removed and the CCF layer will directly contact the CLC material as described in FIG. 4.