Active substrates for color displays

Abstract

An improved electronic display that includes components selected to enhance display performance. The improved display includes an active substrate that has a plurality of thin film transistors and a plurality of thermally transferred color filters that include a colorant in a crosslinked binder. The active substrate can also include a black matrix. Other components in the improved display such as a liquid crystal material, spacers, and bottom polarizer, can be selected to enhance display performance characteristics such as brightness, power consumption, response time, weight, and thickness. The invention also provides a method of forming a color filter substrate for displays including the steps of thermally mass transferring a plurality of color filters and crosslinking the plurality of color filters after transfer. Before the crosslinking step, the plurality of color filters can be inspected and removed for reworking of the substrate.

What is claimed is:  
     
         1 . An electronic display comprising: 
 a light source;    a polarizer disposed to transmit and polarize a portion of light from the light source; and    a liquid crystal display panel disposed to utilize polarized light transmitted by the polarizer, the display panel including 
 a bottom substrate,  
 a top substrate spaced a distance apart from the bottom substrate,  
 a bistable liquid crystal layer comprising a fluorinated chiral ferroelectric liquid crystal material disposed between the top and bottom substrates, and  
 a multi-color active layer disposed between the bottom substrate and the liquid crystal layer, including a plurality of independently addressable active elements electrically connected to transparent conductive sub-pixel elements and a plurality of thermally transferred color filters that include a colorant in a crosslinked composition, each color filter aligned with one or more of the transparent conductive sub-pixel elements.  
   
     
     
         2 . The electronic display of    claim 1   , further comprising a black matrix disposed on the active substrate to separate sub-pixels, the black matrix having an optical density sufficient to provide optical contrast between sub-pixels and a resistivity to substantially prevent crosstalk between adjacent independently addressable transistors.  
     
     
         3 . The electronic display of    claim 1   , further comprising a plurality of spacers disposed between the first and second substrates to maintain a substantially uniform gap therebetween.  
     
     
         4 . The electronic display of    claim 3   , wherein the spacers are selectively thermally mass transferred.  
     
     
         5 . The electronic display of    claim 1   , wherein the polarizer includes a birefringent reflective polarizer and a dichroic polarizer interposed between the reflective polarizer and the bottom substrate.  
     
     
         6 . An electronic display comprising: 
 a first transparent substrate having a plurality of independently addressable thin film transistors disposed thereon, each transistor electrically connected to an associated transparent conductive sub-pixel element;    a second transparent substrate spaced a distance apart from the first transparent substrate;    a liquid crystal layer disposed between the first substrate and the second substrate; and    a plurality of thermally transferred color filters disposed between the first substrate and the liquid crystal layer, the color filters comprising a colorant in a crosslinked composition, each color filter aligned with one or more of the transparent conductive elements associated with the transistors.    
     
     
         7 . The electronic display of    claim 6   , further comprising a black matrix disposed on the first substrate, the black matrix having an optical density sufficient to provide optical contrast between sub-pixels and a resistivity to substantially prevent crosstalk between adjacent independently addressable transistors.  
     
     
         8 . The electronic display of    claim 6   , further comprising a plurality of spacers disposed between the first and second substrates to maintain a substantially uniform gap therebetween.  
     
     
         9 . The electronic display of    claim 8   , wherein the spacers are disposed to prevent light induced activation of the transistors.  
     
     
         10 . The electronic display of    claim 6   , further comprising a light source and a reflective polarizer disposed to transmit to the liquid crystal layer light from the light source having a first polarization state and to reflect light having a second, orthogonal polarization state back toward the light source.  
     
     
         11 . A process for making a color display substrate comprising the steps of: 
 providing a display substrate;    thermally mass transferring a plurality of color filters to selected portions of the substrate, each color filter comprising a colorant in a crosslinkable composition; and    crosslinking the color filters after the transferring step.    
     
     
         12 . The process of    claim 11   , further comprising the steps of: 
 inspecting the color filters after the transferring step and prior to the crosslinking step; and    performing a washing step, if necessary, to remove the color filters from the substrate for reworking of the active substrate.    
     
     
         13 . The process of    claim 11   , wherein the step of thermally mass transferring a plurality of color filters comprises: 
 providing a donor sheet comprising a base layer, a light to heat converter, and a transfer layer comprising a colorant in a crosslinkable composition;    placing the transfer layer proximate to the display substrate; and    selectively irradiating portions of the donor sheet to thermally transfer portions of the transfer layer from the donor sheet to the display substrate.    
     
     
         14 . The process of    claim 11   , further comprising the step of forming a black matrix on the display substrate.  
     
     
         15 . The process of    claim 11   , wherein the display substrate includes a plurality of independently addressable active devices.  
     
     
         16 . The process of    claim 15   , further comprising the step of forming through holes in the color filters to allow electrical connection of transparent conductive sub-pixel electrodes to the independently addressable active devices.  
     
     
         17 . The process of    claim 16   , wherein the step of forming through holes in the color filters comprises patterning a photoresist on the color filters and etching portions of the color filters left exposed by the patterned photoresist.  
     
     
         18 . The process of    claim 16   , wherein the step of forming through holes in the color filters comprises laser ablating portions of the color filters.  
     
     
         19 . A process for making a display substrate comprising the steps of: 
 providing an active display substrate having a plurality of independently addressable active devices thereon;    thermally transferring a plurality of color filters to the active substrate, each color filter comprising a colorant in a crosslinkable composition;    inspecting the color filters after the transferring step;    performing a washing step, if necessary, to remove the color filters from the active substrate for reworking of the active substrate; and    crosslinking the color filters after the inspecting step.    
     
     
         20 . The process of    claim 19   , wherein the step of thermally transferring a plurality of color filters comprises: 
 providing a donor sheet comprising a base layer, a light to heat converter, and a transfer layer comprising a colorant in a crosslinkable composition;    placing the transfer layer proximate to the active substrate; and    selectively irradiating portions of the donor sheet to thermally transfer portions of the transfer layer from the donor sheet to the active substrate.