Method and apparatus for sensing, measurement or characterization of display elements integrated with the display drive scheme, and system and applications using the same

Abstract

Methods and systems for electrical sensing, measurement and characterization of display elements are described. An embodiment includes integrating the electrical sensing, measurement and characterization with the display drive scheme. This embodiment allows for measurement of DC or operational hysteresis voltages and/or response times of interferometric modulator MEMS devices, for example, to be fully integrated with the display driver IC and/or the display drive scheme. Another embodiment allows these measurements to be performed and used without resulting in display artifacts visible to a human user. Another embodiment allows the measurement circuitry to be integrated with the display driver IC and/or the display drive scheme re-using several existing circuitry components and features, thus allowing for integration of the measurement method and its use relatively easily.

1 . A method of operating a device, comprising:
 applying a drive signal across a first and second electrodes of the device, wherein the drive signal alters a state of the device from a first state to a second state and back to the first state, wherein the transition from the first state to the second state and back to the first state has a duration which causes the transition to be substantially undetectable to a viewer; and   determining at least one operational characteristic of the device based on an electrical response of the device to the applied drive signal.   
     
     
         2 . The method of  claim 1 , wherein the transition from the first state to the second state and back to the first state is completed in less than 400 microseconds. 
     
     
         3 . The method of  claim 1 , wherein the transition from the first state to the second state and back to the first state is completed in more than about 400 microseconds and less than about 4000 microseconds. 
     
     
         4 . The method of  claim 1 , further comprising repeating the applying and the determining on a periodic time basis. 
     
     
         5 . The method of  claim 1 , further comprising repeating the applying and the determining on a pseudorandom time basis. 
     
     
         6 . The method of  claim 1 , further comprising repeating the applying and the determining at a time based on a temperature change. 
     
     
         7 . The method of  claim 1 , further comprising performing the applying and the determining based on an age of the device. 
     
     
         8 . The method of  claim 1 , wherein the applying is performed multiple times at various levels and an operational characteristic is determined for each of the various levels, the method further comprising:
 storing information indicative of the operational characteristic and the level for each of the various levels, and   determining a drive level based on the stored information and a predetermined operational characteristic.   
     
     
         9 . The method of  claim 1 , wherein determining the at least one operational characteristic comprises determining one or more of an actuation voltage, a release voltage and a response time. 
     
     
         10 . The method of  claim 1 , wherein the drive signal comprises one or more of a sinusoid, a saw tooth and a rectangular pulse. 
     
     
         11 . A characterization apparatus, comprising:
 drive circuitry configured to apply a drive signal across first and second electrodes of a device, wherein the drive signal alters a state of the device from a first state to a second state and back to the first state, wherein the transition from the first state to the second state and back to the first state has a duration which causes the transition to be substantially undetectable to a viewer; and   a processor configured to receive a response signal indicative of an electrical response of the device to the applied drive signal, and to determine at least one operational characteristic of the device based on the response signal.   
     
     
         12 . The apparatus of  claim 11 , wherein the transition from the first state to the second state and back to the first state is completed in less than 400 microseconds. 
     
     
         13 . The apparatus of  claim 11 , wherein the transition from the first state to the second state and back to the first state is completed in more than about 400 microseconds and less than about 4000 microseconds. 
     
     
         14 . The apparatus of  claim 11 , wherein the processor is configured to control the drive circuitry to apply the drive signal on a periodic time basis. 
     
     
         15 . The apparatus of  claim 11 , wherein the processor is configured to control the drive circuitry to apply the drive signal on a pseudorandom time basis. 
     
     
         16 . The apparatus of  claim 11 , wherein the processor is configured to control the drive circuitry to apply the drive signal at a time based on a temperature change. 
     
     
         17 . The apparatus of  claim 11 , wherein the processor is configured to control the drive circuitry to apply the drive signal based on the age of the device. 
     
     
         18 . The apparatus of  claim 11 , wherein the processor is configured to control the drive circuitry to apply the drive signal multiple times at various levels, determine an operational characteristic associated with each of the multiple levels, store information indicative of the operational characteristics and the levels, and determine a drive level based on the stored information and a predetermined operational characteristic. 
     
     
         19 . The apparatus of  claim 18 , wherein the at least one operational characteristic comprises one or more of an actuation voltage, a release voltage and a response time. 
     
     
         20 . The apparatus of  claim 11 , wherein the signal comprises one or more of a sinusoid, a saw tooth and a rectangular pulse. 
     
     
         21 . The apparatus of  claim 11 , wherein the processor is configured to control the drive circuitry to apply the drive signal to provide temporal averaging of a displayed color. 
     
     
         22 . A characterization device, comprising:
 means for applying a drive signal across first and second electrodes of a device, wherein the drive signal alters a state of the device from a first state to a second state and back to the first state, wherein the transition from the first state to the second state and back to the first state has a duration which causes the transition to be substantially undetectable to a viewer; and   means for receiving a response signal indicative of an electrical response of the device to the applied drive signal, and to determine at least one operational characteristic of the device based on the response signal.   
     
     
         23 . The device of  claim 22 , wherein the means for applying comprises drive circuitry. 
     
     
         24 . The device of  claim 22 , wherein the means for receiving comprises a processor. 
     
     
         25 . The device of  claim 22 , wherein the transition from the first state to the second state and back to the first state is completed in less than 400 microseconds. 
     
     
         26 . The device of  claim 22 , wherein the transition from the first state to the second state and back to the first state is completed in more than about 400 microseconds and less than about 4000 microseconds. 
     
     
         27 . The device of  claim 22 , wherein the applying means is configured to apply the drive signal at a time based on a temperature change. 
     
     
         28 . The device of  claim 22 , wherein the applying means is configured to apply the drive signal at a time based on an age of the device. 
     
     
         29 . The device of  claim 22 , the wherein the applying means is configured to apply the drive signal multiple times at various levels and the means for receiving is configured to determine an operational characteristic for each of the various levels, the device further comprising:
 means for storing information indicative of the operational characteristic and the level for each of the various levels, and   means for determining a drive level based on the stored information and a predetermined operational characteristic.   
     
     
         30 . The device of  claim 22 , wherein the means for receiving is configured to determine one or more of an actuation voltage, a release voltage and a response time. 
     
     
         31 . A characterization device comprising:
 an array of interferometric modulators;   drive circuitry configured to apply a drive signal across first and second electrodes of a device, wherein the drive signal alters a state of the device from a first state to a second state and back to the first state, wherein the transition from the first state to the second state and back to the first state has a duration which causes the transition to be substantially undetectable to a viewer;   a processor configured to receive a response signal indicative of an electrical response of the device to the applied drive signal, and to determine at least one operational characteristic of the device based on the response signal; and   a memory device configured to communicate with the processor.   
     
     
         32 . The device of  claim 31 , further comprising a controller configured to send image data to the drive circuitry. 
     
     
         33 . The device of  claim 31 , further comprising an image source module configured to send image data to the processor. 
     
     
         34 . The device of  claim 33 , wherein the image source module comprises at least one of a receiver, transceiver, and transmitter. 
     
     
         35 . The device of  claim 31 , further comprising an input device configured to receive input data and to communicate the input data to the processor.