Method and apparatus for front-lit semi-retro-reflective display

Abstract

The disclosure generally relates to a front-lit display having transparent and selectively emissive light directionality. The disclosed semi-retro-reflective, semi-specular and specular displays include directional front light systems that reflect light in a manner to preserve the non-Lambertian characteristic of the light output. This leads to brighter displays with a higher degree of luminance as compared to conventional microencapsulated electrophoretic displays with substantially Lambertian reflectance where much of the light is not reflected back towards the viewer.

what is claimed is: 
     
         1 . A reflective display device, comprising:
 a semi-retro-reflective display sheet having one or more convex protrusions that reflects light in a narrow angle relative to the direction of the incident light;   a light source to emit light in a perpendicular direction towards the display sheet;   a front electrode;   a rear electrode;   a fluid disposed between the front and the rear electrodes;   a plurality of electrophoretically mobile particles suspended in the optically transparent fluid; and   a voltages source in communication to the front and the rear electrodes to selectively move the electrophoretically mobile particles in the fluid.   
     
     
         2 . The display of  claim 1 , wherein the light source defines a light emitting diode (LED), cold cathode fluorescent lamp (CCFL) or a surface mount technology (SMT) incandescent lamp. 
     
     
         3 . The display of  claim 1 , wherein the front electrode is transparent and disposed on the semi-retro-reflective display sheet. 
     
     
         4 . The display of  claim 1 , wherein the rear electrode further comprises a thin film transistor or driven patterned array. 
     
     
         5 . The display of  claim 1 , wherein the fluid defines an optically transparent fluid a refractive index lower than an index of refraction of the semi-retro-reflective display sheet. 
     
     
         6 . The display of  claim 1 , wherein the voltage source provides:
 a first voltage to move substantially all of the electrophoretically mobile particles toward the rear electrode to allow incident rays to be internally reflected at the semi-retro-reflective display sheet towards the viewer; and   a second voltage to move substantially all of the electrophoretically mobile particles toward the front electrode and collect at the semi-retro-reflective surface to thereby frustrate total internal reflection.   
     
     
         7 . The display of  claim 1 , further comprising one or more cross walls. 
     
     
         8 . The display of  claim 1 , wherein the front light and the semi-retro-reflective display sheet are arranged relative to each other to provide a substantially non-Lambertian light display. 
     
     
         9 . The display of  claim 1 , wherein the narrow angle defines an angle in the range of about 10° to about 30°. 
     
     
         10 . A reflective display, comprising:
 a transparent outer sheet;   a light source to emit light in a perpendicular direction towards the transparent outer sheet;   a rear electrode;   a perforated sheet situated between the light source and the rear electrode;   a front electrode disposed over the perforated sheet;   a semi-retro-reflective surface over the perforated sheet;   a medium disposed within the cavity formed between the transparent outer sheet and the rear electrode;   a plurality of electrophoretically mobile particles suspended in the medium; and   a voltages source in communication to the front and the rear electrodes to selectively move the electrophoretically mobile particles in the fluid.   
     
     
         11 . The display of  claim 10 , further comprising one or more cross walls. 
     
     
         12 . The display of  claim 10 , wherein the light source and the semi-retro-reflective surface are arranged relative to each other to provide a substantially non-Lambertian light display. 
     
     
         13 . The display of  claim 10 , wherein the rear electrode further comprises a thin film transistor or driven patterned array. 
     
     
         14 . The display of  claim 10 , wherein the voltage source provides:
 a first voltage to move substantially all of the electrophoretically mobile particles toward the rear electrode to allow incident rays to be reflected at the semi-retro-reflective display sheet towards the viewer; and   a second voltage to move substantially all of the electrophoretically mobile particles toward the front electrode and collect at the semi-retro-reflective surface to thereby absorb incident rays.   
     
     
         15 . A reflective display, comprising:
 a transparent outer sheet;   a light source to emit light in a perpendicular direction towards the transparent outer sheet;   a rear electrode;   a perforated sheet situated between the light source and the rear electrode;   a reflective layer disposed over the perforated sheet;   a transparent front electrode disposed over the perforated sheet;   a medium disposed within the cavity formed between the transparent outer sheet and the rear electrode;   a plurality of electrophoretically mobile particles suspended in the medium; and   a voltages source in communication to the front and the rear electrodes to selectively move the electrophoretically mobile particles in the fluid.   
     
     
         16 . The display of  claim 15 , further comprising one or more cross walls. 
     
     
         17 . The display of  claim 15 , wherein the light source and the semi-retro-reflective surface are arranged relative to each other to provide a substantially non-Lambertian light display. 
     
     
         18 . The display of  claim 15 , wherein the rear electrode further comprises a thin film transistor or driven patterned array. 
     
     
         19 . The display of  claim 15 , wherein the transparent front electrode is comprised of ITO or Baytron™ or electrically conductive particles dispersed in a polymer matrix or a combination thereof. 
     
     
         20 . The display of  claim 15 , wherein the voltage source provides:
 a first voltage to move substantially all of the electrophoretically mobile particles toward the rear electrode to allow incident rays to be reflected at the semi-retro-reflective display sheet towards the viewer; and   a second voltage to move substantially all of the electrophoretically mobile particles toward the front electrode and collect at the semi-retro-reflective surface to thereby absorb incident rays.