Global Oled Technology LLC

Eastman-Kodak Company

Felipe A Leon

Christopher J White

Gary Parrett

Ronald S Cok

Charles I Levey

Bruno Primerano

Michael E Miller

John W Hamer

John Ludwicki

An electroluminescent (EL) panel with 2T1C subpixels is compensated for initial nonuniformity ('mura'). The current of each subpixel is measured at a selected time to provide a status signal representing the characteristics of the subpixel. A compensator receives a linear code value and changes it according to the status signals. A linear source driver drives the panel with the changed code values.

Electroluminescent display initial-nonuniformity-compensated drve signal

An electroluminescent (EL) device including an illumination area having one or more primary EL emitters; a reference area having a reference EL emitter; a reference driver circuit for causing the reference EL emitter to emit light while the EL device is active; a sensor for detecting light emitted by the reference EL emitter; and a measurement unit for detecting an aging-related electrical parameter of the reference EL emitter while it is emitting light. The device further includes a controller for receiving an input signal for each primary EL emitter in the illumination area, forming a corrected input signal from each input signal using the detected light and the aging-related electrical parameter, and applying the corrected input signals to the respective primary EL emitters in the illumination area.

Electroluminescent device aging compensation with reference subpixels

An electroluminescent (EL) subpixel having a readout transistor is driven by a current source when the drive transistor is non-conducting. This produces an emitter-voltage signal from which an aging signal representing the efficiency of the EL emitter can be computed. The aging signal is used to adjust an input signal to produce a compensated drive signal to compensate for changes in efficiency of the EL emitter.

Electroluminescent display with efficiency compensation

Inoperative or defective electroluminescent (EL) emitters in an EL display having a plurality of subpixels are detected. Current flow through a drive transistor in a subpixel is turned off, a selected test current is provided through the EL emitter in the subpixel using a current source, and the voltage at a second electrode of a readout transistor in the subpixel is measured to provide a status signal representative or characteristics of the selected EL emitter. The status signal for the subpixel is compared to the respective status signals of neighboring subpixels to determine whether the EL emitter in the subpixel is defective.

Defective emitter detection for electroluminescent display

A method of compensating image signals for driving an OLED display having a plurality of light-emitting elements having outputs that change with time or use, comprising the steps of: a) obtaining a measured or estimated first value of the current used by individual light-emitting elements in response to known image signals at a first time; b) specifying multiple groups of light-emitting elements at a second time, wherein at least one of the specified groups contains at least one light-emitting element common to another specified group; c) measuring total currents used by each of the specified groups in response to known image signals at a second time; d) forming an estimated second value of the current used by individual light-emitting elements based on the measured total currents, e) calculating correction values for individual light-emitting elements based on the difference between the first and second current values, and f) employing the correction values to compensate image signals for the changes in the output of the light-emitting elements and produce compensated image signals.

OLED display with aging compensation

An electroluminescent (EL) subpixel driven by a digital-drive scheme has a readout transistor driven by a current source when the drive transistor is non-conducting. This produces an emitter-voltage signal from which an aging signal representing the efficiency of the EL emitter can be computed. The aging signal is used to determine the loss in current of the subpixel when active, and an input signal is adjusted to provide increased on-time to compensate for voltage rise and efficiency loss of the EL emitter. Variations due to temperature can also be compensated for.

Digital-drive electroluminescent display with aging compensation

Apparatus for providing an analog drive transistor control signal to the gate electrode of a drive transistor in a drive circuit that applies current to an EL device, the drive circuit including a first supply electrode of the drive transistor and the EL device connected to a second supply electrode of the drive transistor, comprising a measuring circuit for measuring the current passing through the supply electrodes at different times to provide an aging signal representing variations in the characteristics of the drive transistor and EL device caused by operation of the drive transistor and EL device over time; a compensator for changing a linear code value in response to the aging signal to compensate for the variations in the characteristics of the drive transistor and EL device; and a linear source driver for producing the analog drive transistor control signal in response to the changed linear code value.

Electroluminescent display compensated analog transistor drive signal

A method of compensating for changes in the characteristics of transistors and EL devices in an EL display, includes providing an EL display having a two-dimensional array of EL devices arranged in rows and columns, wherein each EL device is driven by a drive circuit in response to a drive signal; providing a first drive circuit for an EL device having three transistors and providing a second drive circuit for an EL device having only two transistors, and wherein a first column in the display includes at least one first drive circuit and an adjacent second column includes at least one second drive circuit; deriving a correction signal based on the characteristics of a transistor in a first drive circuit, or the EL device; and using the correction signal to adjust the drive signals applied to the first drive circuit and one or more adjacent second drive circuits.

Electroluminescent display with interleaved 3T1C compensation

A method for controlling and compensating aging in an LED device includes measuring a performance change in light output of the LED device. The LED device is controlled with a first compensation algorithm derived from the measured performance change, during a first period, to effect a luminance change over time in the light output of the LED device. Subsequently, a second compensation algorithm, derived from the measured performance change, and different from the first compensation algorithm, during a second period, effects a second luminance change over time in the LED device's light output. The second luminance change over time in the second period is different from the first luminance change over time in the first period. Furthermore, the first and second periods together are less than the lifetime of the LED device.

LED device compensation method

Compensated drive circuit adjusting for changes in the threshold voltage of a drive transistor and for aging of an OLED device, comprising: a data line carrying analog data representative of the brightness level, and a select line; the drive transistor connected to a power supply and to the OLED device such that when the select line is activated and a voltage from the data line is applied to the gate electrode of such transistor and current proportional to the applied voltage will flow through the drain and source electrodes through the OLED device; circuitry for measuring first and second parameters associated with the drive circuitry and responsive to the measured first and second parameters for computing offset voltages to adjust for changes in the threshold voltage of the drive transistors and for aging of the OLED device.

OLED display with aging and efficiency compensation

An OLED device comprising: a) a substrate; b) one or more OLED element(s) formed on the substrate and having a common electrical connection for passing current through the OLED element(s); c) one or more transistor circuit(s) for controlling current passing through the OLED element(s); and d) a controller for measuring a current passing through the common electrical connection when the OLED element(s) and/or transistor circuit(s) are at an unknown temperature, for controlling the transistor circuit(s), and for comparing the current measured to an established current response determined under known OLED element(s) and/or transistor circuit(s) temperature conditions to determine the temperature of the OLED element(s) and/or transistor circuit(s).

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Rochester, NY, United States of America

Felipe A Leon