Adjustment of display illumination timing

Abstract

A display device adjusts the operational timing of the illumination source relative to pixels of the display device. Grayscale may be generated in the pixels using pulse width modulation. The operational timing may be adjusted based on the temperature of the display device. The display device may be a liquid crystal display device and the operational timing of the illumination source may be adjusted to compensate for variation in the response time of the liquid crystal material based on temperature.

1 . A display device, comprising:
 a light source; and   an array of active pixels arranged in rows and columns, the array of active pixels are electronically controllable to operate in a first light modulating state where light from the light source is substantially blocked from an output of the display device and a second light-modulating state where light from the light source is substantially passed to the output;   wherein the display device adjusts operational timing of the light source and the array of pixels based on a measured temperature of the display device.   
     
     
         2 . The display device of  claim 1 , the array of active pixels further comprising a layer of liquid crystal material that rotates polarization of the light from the light source. 
     
     
         3 . The display device of  claim 2 , wherein a response time of the liquid crystal material depends on temperature of the liquid crystal material, and wherein the operational timing of the light source and the array of pixels at a measured temperature value is related to the response time of the liquid crystal material at the measured temperature value. 
     
     
         4 . The display device of  claim 2 , further comprising a polarizing beam splitter, wherein the first light modulating state affects polarization of the light from the light source such that it is substantially internally reflected by the polarizing beam splitter and the second light modulating state affects polarization of the light from the light source such that it is substantially passed through the polarizing beam splitter. 
     
     
         5 . The display device of  claim 1 , wherein the light source comprises a light-emitting diode. 
     
     
         6 . The display device of  claim 5 , wherein the light source comprises red, green, and blue light-emitting diodes. 
     
     
         7 . The display device of  claim 1 , further comprising a non-volatile memory coupled to the liquid crystal display device, wherein the non-volatile memory stores values for operational timing of the light source relative to the array of pixels at a plurality of temperature points. 
     
     
         8 . A display device, comprising:
 an illumination source;   an array of pixel electrodes that switch between a first pixel voltage and a second pixel voltage, wherein the array of pixel electrodes are set to the first pixel voltage during a blanking period of a display phase and switch during a light-modulating period of the display phase to the second pixel voltage;   a common electrode driven by a common voltage; and   a layer of liquid crystal material between the array of pixel electrodes and the common electrode, wherein light-modulating states of the liquid crystal material are determined by voltage fields between the array of pixel electrodes and the common electrode;   wherein a time period between the beginning of the light-modulating period and onset o of the illumination source is adjusted based on a measured temperature.   
     
     
         9 . The display device of  claim 8 , wherein the layer of liquid crystal material comprises a ferroelectric liquid crystal layer. 
     
     
         10 . The display device of  claim 9 , wherein the time period is adjusted to be proportional to a measured optical response of the ferroelectric liquid crystal material at the measured temperature. 
     
     
         11 . The display device of  claim 8 , wherein a pixel electrode set to the first pixel voltage produces a first light-modulating state in the layer of liquid crystal material where light from the illumination source is substantially passed to an output of the display device. 
     
     
         12 . A method of adjusting the operation of a display device having an array of pixels operable to switch between light-modulating states, wherein grayscale for a pixel of the array of pixels is generated by pulse width modulation of the light-modulating states during a light-modulating time period, the method comprising:
 determining an approximate temperature of the display device; and   adjusting an illumination delay time period between the start of the light-modulating time period and onset of illumination of the array of pixels based on the determined approximate temperature.