Active-matrix display and pixel structure for feedback stabilized flat panel display

Abstract

An emissive pixel device having integrated luminance sensor and a method of operating an emissive pixel device having an integrated luminance or photon flux sensor. Device includes light or photon emitting device, drive circuit generating current to drive light emitting device to predetermined luminance corresponding to an image voltage and applying drive current to light emitting device during frame time, photo sensor that exhibits change in electrical characteristic in response to change in incident photon flux disposed near the light emitting device to intercept measurable photon flux when light emitting device is in emitting state, charge storage device coupled with sensor for accumulating or releasing charges and exhibiting capacitance charge and voltage proportional to the charge at a time; and control circuit controlling charging and discharging of charge storage device in response to changes in electrical characteristics of sensor during at least a portion of the frame time.

1 . An emissive pixel device having an integrated luminance sensor, the pixel device comprising: 
 a light emitting device;    a drive circuit generating a current to drive the light emitting device to a predetermined luminance corresponding to an image voltage and applying the drive current to the light emitting device during a frame time;    a photo sensor that exhibits a change in electrical characteristic in response to a change in incident photon flux disposed near the light emitting device to intercept a measurable photon flux when the light emitting device is in an emitting state;    a charge storage device coupled with the sensor for accumulating or releasing charges and exhibiting a capacitance charge and voltage proportional to the charge at a time; and    a control circuit controlling the charging and discharging of the charge storage device in response to changes in the electrical characteristics of the sensor during at least a portion of the frame time.    
     
     
         2 . An emissive pixel device as in  claim 1 , further comprising: a voltage reading circuit for measuring the voltage across the charge storage device at the end of the at least a portion of a display frame time, the measured voltage being an indication of a measured luminance of the pixel during the portion of the frame time.  
     
     
         3 . An emissive pixel device as in  claim 1 , further comprising: a current reading circuit for measuring the current from the charge storage device at the end of the at least a portion of a display frame time, the measured current being an indication of a measured luminance of the pixel during the portion of the frame time.  
     
     
         4 . An emissive pixel device as in  claim 1 , further comprising: a charge reading circuit for measuring the charge on the charge storage device at the end of the at least a portion of a display frame time, the measured charge being an indication of a measured luminance of the pixel during the portion of the frame time.  
     
     
         5 . An emissive pixel device as in  claim 2 , further comprising a feedback control circuit for applying a correction to the pixel drive circuit during a subsequent frame time so that the measured luminance during the subsequent frame time will have a smaller variation from the reference luminance than during the frame time of the measurement.  
     
     
         6 . An emissive pixel device as in  claim 2 , wherein the voltage across the charge storage device represents an integrated photon flux during the portion of the frame time over which the control circuit permitted charging or discharging or the charge storage device.  
     
     
         7 . An emissive pixel device as in  claim 2 , wherein the voltage reading circuit further comprising a voltage comparator circuit that receives the voltage across the charge storage device and a reference voltage corresponding to a target luminance and generates a difference signal representing the difference between the target luminance and the measured luminance.  
     
     
         8 . An emissive pixel device as in  claim 3 , wherein the current reading circuit further comprising a current comparator circuit that receives the current from, the charge storage device and a reference current corresponding to a target luminance and generates a difference signal representing the difference between the target luminance and the measured luminance.  
     
     
         9 . An emissive pixel device as in  claim 4 , wherein the charge reading circuit further comprising a charge comparator circuit that receives the charge on the charge storage device and a reference charge corresponding to a target luminance and generates a difference signal representing the difference between the target luminance and the measured luminance.  
     
     
         10 . An emissive pixel device as in  claim 2 , wherein the read circuit is configured as a charge amp/transimpedance amplifier having a charge amplifier circuit.  
     
     
         11 . An emissive pixel device as in  claim 10 , wherein the charge amp/transimpedance amplifier measures the charge required to re-charge the storage capacitor to the full charge voltage, and that an inverting (−) input of the charge amplifier circuit has a resistance that is at least one Gig-ohm and the output of the charge amplifier circuit has a resistance that is between about 0 ohms and 100 ohms.  
     
     
         12 . An emissive pixel device as in  claim 11 , wherein the resistance of the output of the charge amplifier circuit is a resistance that is substantially between 0 ohms and 10 ohms.  
     
     
         13 . An emissive pixel device as in  claim 1 , wherein the control circuit comprises at least one transistor.  
     
     
         14 . An emissive pixel device as in  claim 1 , wherein the charge storage device comprises at least one capacitor.  
     
     
         15 . An emissive pixel device as in  claim 1 , wherein the charge storage device comprises multiple capacitors.  
     
     
         16 . An emissive pixel device as in  claim 1 , wherein the sensor device comprises a photoresistive or photoconductive device having a resistivity or conductivity that varies according to the number of photons incident on it.  
     
     
         17 . An emissive pixel device as in  claim 1 , wherein the light emitting device emits photons.  
     
     
         18 . An emissive pixel device as in  claim 1 , wherein the light emitting device comprises a light emitting diode.  
     
     
         19 . An emissive pixel device as in  claim 1 , wherein the light emitting device comprises an organic light emitting diode.  
     
     
         20 . An emissive pixel device as in  claim 1 , wherein the light emitting device comprises an inorganic light emitting diode.  
     
     
         21 . An emissive pixel device as in  claim 1 , wherein the light emitting device is one of a plurality of light emitting devices arranged as a two-dimensional array arranged as rows and columns.  
     
     
         22 . An emissive pixel device as in  claim 21 , wherein the light emitting device comprises a light emitting diode.  
     
     
         23 . An emissive pixel device as in  claim 21 , wherein the light emitting device comprises an organic light emitting diode.  
     
     
         24 . An emissive pixel device as in  claim 23 , wherein the organic light emitting diode (OLED) is a small molecule OLED.  
     
     
         25 . An emissive pixel device as in  claim 23 , wherein the organic light emitting diode (OLED) is a polymer OLED (PLED).  
     
     
         26 . An emissive pixel device as in  claim 23 , wherein the organic light emitting diode (OLED) is a phosphorescent OLED (PHOLED).  
     
     
         27 . An emissive pixel device as in  claim 23 , wherein the organic light emitting diode (OLED) is constructed from any organic material in any combination of single or multiple layers of organic materials and electrodes.  
     
     
         28 . An emissive pixel device as in  claim 23 , wherein the organic light emitting diode (OLED) is a active matrix OLED.  
     
     
         29 . An emissive pixel device as in  claim 23 , wherein the display device is an electroluminescent device.  
     
     
         30 . An emissive pixel device as in  claim 23 , wherein the display device is an plasma emission device.  
     
     
         31 . An emissive pixel device as in  claim 23 , wherein the display device is any controllable photon emissive device.  
     
     
         32 . An emissive pixel device as in  claim 23 , wherein the active matrix display device is constructed from amorphous silicon.  
     
     
         33 . An emissive pixel device as in  claim 23 , wherein the active matrix display device is constructed from poly-silicon.  
     
     
         34 . An emissive pixel device as in  claim 23 , wherein the active matrix display device is constructed from cadmium selenide.  
     
     
         35 . An emissive pixel device as in  claim 23 , wherein the active matrix display device is constructed from any type of semiconductor material.  
     
     
         36 . An emissive pixel device as in  claim 1 , wherein the photo sensor element includes a resistive component and the resistance changes in proportion to the photon flux incident upon it.  
     
     
         37 . An emissive pixel device as in  claim 1 , wherein the photo sensor element includes photodiode exhibiting a change of resistance and/or conductance in response to photon flux incident upon it.  
     
     
         38 . An emissive pixel device as in  claim 1 , wherein the photo sensor element includes phototransistor exhibiting a change of resistance and/or conductance in response to photon flux incident upon it.  
     
     
         39 . An emissive pixel device as in  claim 1 , wherein the photo sensor intercepts photons emitted by the light emitting device and converts them to charge carriers making the material of the sensor a better current conductor and thus having lower electrical resistance.  
     
     
         40 . An emissive pixel device as in  claim 1 , wherein the lower resistance of the photo sensor drains a charge stored on a capacitor coupled in parallel across a two-terminal resistive component of the sensor.  
     
     
         41 . An emissive pixel device as in  claim 1 , wherein the pixel circuit includes a photon flux count integrator comprising the sensor having a resistive component and a capacitor.  
     
     
         42 . An emissive pixel device as in  claim 1 , wherein the amount of drained charge is proportional to the number of photons incident on the sensor during a portion of the frame time and the voltage on the capacitor at the end of the portion of the frame time is an indicator of the photons counted or integrated during the portion of the frame time.  
     
     
         43 . An emissive pixel device as in  claim 1 , wherein a particular luminance level produces a photocurrent in the sensor, and the magnitude of the photocurrent serves as an indication of the luminance (photon flux through the sensor).  
     
     
         44 . An emissive pixel device as in  claim 24 , wherein the photocurrent is proportional to the luminance.  
     
     
         45 . An emissive pixel device as in  claim 25 , wherein the photocurrent is directly proportional to the luminance.  
     
     
         46 . An emissive pixel device as in  claim 1 , wherein the photo responsive element is disposed within the same pixel as the light emitting diode.  
     
     
         47 . An emissive pixel device as in  claim 1 , wherein the photo responsive element is integrated with the light emitting diode so that all or substantially all the photon flux emitted by the light emitting diode is incident on the photo responsive element.  
     
     
         48 . An emissive pixel device as in  claim 1 , wherein the photo responsive element has a surface or layer that is physically located in contact with a semiconductor anode side of the light emitting device.  
     
     
         49 . An emissive pixel device as in  claim 1 , wherein the portion of the frame time comprises the row address time or less.  
     
     
         50 . An emissive pixel device as in  claim 1 , wherein the portion of the frame time comprises substantially the entire frame time.  
     
     
         51 . An emissive pixel device as in  claim 1 , wherein the portion of the frame time comprises at least 50 percent of the entire frame time.  
     
     
         52 . An emissive pixel device as in  claim 1 , wherein the portion of the frame time comprises at least between 90 percent and 100 percent of the entire frame time.  
     
     
         53 . An emissive pixel device as in  claim 1 , wherein the portion of the frame time comprises at least 1 millisecond.  
     
     
         54 . An emissive pixel device as in  claim 1 , wherein the portion of the frame time is equal to or less than the row address time.  
     
     
         55 . A method of operating an emissive pixel device having an integrated luminance sensor, the method comprising: 
 generating a current to drive a light emitting device to a predetermined luminance corresponding to an image voltage and applying the drive current to the light emitting device during a frame time;    a charge storage device coupled with the sensor for accumulating or releasing charges and exhibiting a capacitance charge and voltage proportional to the charge at a time;    exposing a photo sensor that exhibits a change in electrical characteristic in response to a change in incident photon flux to photons emitted by the light emitting device during the frame time;    accumulating (charge) or draining (discharge) charges to or from a charge storage device coupled with the sensor, the sensor including a component that controls the rate of accumulation or release of charges during the frame time;    measuring the voltage arising from the charges present on the charge storage device at the end of a portion of the frame time, the measured voltage being an indication of an actual luminance during the portion of the frame time;    comparing the luminance related measured voltage with a reference target luminance for the pixel emitter image voltage and pixel emitter drive current to generate a difference value; and    applying the difference value as a feedback input to a correction circuit that modifies the image voltage and drive current for the same pixel during a subsequent frame time.    
     
     
         56 . An method as in  claim 34 , wherein the light emitting device comprises an inorganic light emitting diode.  
     
     
         57 . A method as in  claim 34 , wherein the light emitting device comprises an organic light emitting diode (OLED).  
     
     
         58 . A method as in  claim 57 , wherein the organic light emitting diode (OLED) is a small molecule OLED.  
     
     
         59 . A method as in  claim 57 , wherein the organic light emitting diode (OLED) is a polymer OLED (PLED).  
     
     
         60 . A method as in  claim 57 , wherein the organic light emitting diode (OLED) is a phosphorescent OLED (PHOLED).  
     
     
         61 . A method as in  claim 57 , wherein the organic light emitting diode (OLED) is constructed from any organic material in any combination of single or multiple layers of organic materials and electrodes.  
     
     
         62 . A method as in  claim 57 , wherein the organic light emitting diode (OLED) is a active matrix OLED.  
     
     
         63 . A method as in  claim 55 , wherein the display emissive device is an electroluminescent device.  
     
     
         64 . A method as in  claim 55 , wherein the display emissive device is an plasma emission device.  
     
     
         65 . A method as in  claim 55 , wherein the display emissive device is any controllable photon emissive device.  
     
     
         66 . A method as in  claim 62 , wherein the active matrix is constructed from amorphous silicon.  
     
     
         67 . A method as in  claim 62 , wherein the active matrix is constructed from poly silicon.  
     
     
         68 . A method as in  claim 62 , wherein the active matrix is constructed from cadmium selenide.  
     
     
         69 . A method as in  claim 62 , wherein the active matrix is constructed from any type of semiconductor material.  
     
     
         70 . A method as in  claim 55 , wherein the photo sensor intercepts photons emitted by the light emitting device and converts them to charge carriers making the material of the sensor a better current conductor and thus having lower electrical resistance.  
     
     
         71 . A method as in  claim 55 , wherein the amount of accumulated or drained charge is proportional to the number of photons incident on the sensor during a portion of the frame time and the voltage on the capacitor at the end of the portion of the frame time is an indicator of the photons counted or integrated during the portion of the frame time.  
     
     
         72 . A method as in  claim 55 , wherein a particular luminance level produces a photocurrent in the sensor, and the magnitude of the photocurrent serves as an indication of the luminance (photon flux through the sensor).  
     
     
         73 . A method as in  claim 55 , wherein the photo sensor element is disposed within the same pixel as the light emitting diode.  
     
     
         74 . A method as in  claim 55 , wherein the portion of the frame time comprises the row address time or less.  
     
     
         75 . A method as in  claim 55 , wherein the portion of the frame time comprises substantially the entire frame time.  
     
     
         76 . A method as in  claim 55 , wherein the portion of the frame time comprises at least 50 percent of the entire frame time.  
     
     
         77 . A method as in  claim 55 , wherein the portion of the frame time comprises at least between 90 percent and 100 percent of the entire frame time.  
     
     
         78 . A method as in  claim 55 , wherein the portion of the frame time comprises at least 1 millisecond.  
     
     
         79 . A method as in  claim 55 , wherein the portion of the frame time is equal to or less than the row address time.