Korea Advanced Institute of Science and Technology

Lg Chem, Ltd

Young-Suk Son

Gyu-Hyeong Cho

Sang-Kyung Kim

Yong-Joon Jeon

Gyu Hyeong Cho

Sang Kyung Kim

Jin Yong Jeon

Moo-Ho Hong

Boo-Gon Woo

Gun Ho Lee

Gun-Ho Lee

Hyung-Min Lee

Jin-Yong Jeon

Gun-ho Lee

Jin-yong Jeon

Seung-Chul Jung

Min-Chul Lee

Disclosed herein is an Active Matrix Organic Light-Emitting-Diode (AMOLED) drive circuit using transient current feedback. The AMOLED drive circuit includes a current Digital-to-Analog Converter (DAC), a data line drive transistor, a constant current source, a variable current source, a differential amplifier, and a transient charging current control unit. The DAC generates current corresponding to input digital data. The data line drive transistor is configured such that the drain terminal thereof is connected to the output node of the current DAC. The constant current source is connected between the source terminal of the data line drive transistor and a ground. The variable current source is connected between both the output node of the current DAC and the drain terminal of the drive transistor, and a voltage source. The differential amplifier is configured to input the output voltage thereof to the gate terminal of the drive transistor. The transient charging current control unit is configured to increase or decrease the bias current of the variable current source depending on variation in the voltage of the output node of the current DAC.

AMOLED drive circuit using transient current feedback and active matrix driving method using the same

An active matrix organic light emitting diode AMOLED driving circuit using current feedback that ensures the uniformity of brightness in pixels of a flat panel display and shortens the time required to input accurate current to respective pixels in the driving circuit. The prevent invention provides an AMOLED driving circuit using current feedback, comprising: a current digital-to-analog converter outputting a current corresponding to input digital data; a first differential amplifier connected to the current digital-to-analog converter and controlling the input data current and a driving current of a driving transistor of a pixel circuit to be identical to each other; a current mirror mirroring driving current of an organic light emitting diode of the pixel circuit to an input side of the first differential amplifier; and a second differential amplifier coupled to the current mirror and controlling charge and discharge speeds of parasitic capacitance of the pixel circuit.

Active matrix OLED driving circuit using current feedback

A driving apparatus for a display is provided. The driving apparatus for a display comprises a reference voltage generator, a digital-to-analog converter, and an output unit. The reference voltage generator generates a plurality of reference voltages, and receives a difference value between two adjacent reference voltages and generates a plurality of sub reference voltages. The digital-to-analog converter selects one of the reference voltages and outputs the selected reference voltage as a first analog signal. The digital-to-analog converter selects one of the sub reference voltages and outputs the selected reference voltage as a second analog signal. The output unit processes, by addition or subtraction, the first and second analog signals for output.

Driving apparatus for display

Disclosed herein are a pixel circuit and driving method for active matrix Organic Light-emitting Diodes (OLEDs), and a display using the same. The pixel circuit includes a Voltage Control Current Source (VCCS), a high gain amplifier, a storage capacitor, and first and second switches. The VCCS is configured to drive OLEDs. The high gain amplifier is configured such that the control input signal of the VCCS causes the VCCS to be placed in an ON or OFF state. The storage capacitor is located between the input terminal of the high gain amplifier and a data line so as to assign the ON-time of the VCCS. The first and second switches are configured to be controlled through a scan line so as to store voltage in the storage capacitor and control the light-emitting time of the OLEDs, and are formed the input terminal of the high gain amplifier and the input terminal of the VCCS, respectively.

Pixel circuit and driving method for active matrix organic light-emitting diodes, and display using the same

Disclosed herein is a driving method and circuit for the automatic voltage output of an active matrix organic light emitting device, which is capable of resolving the non-uniformity of brightness between pixels. The circuit of the present invention includes timing generation means for generating a data drive start signal; sweep voltage generation means for generating a sweep voltage signal in response to output of the timing generation means; current level detection means for sensing an amount of current, which flows into pixels, based on output of the sweep voltage generation means, and outputting a sensing result to a data line; comparison means for comparing output of the current level detection means with a reference signal that determines stop timing for data writing, and outputting a comparison result; and data writing start/end control signal generation means for starting to operate in response to the output of the timing generation means, and generating data writing start and end control signals to a program stop line of a display panel. The invention can shorten data writing time and improve the precision of data writing. Furthermore, the present invention can simplify a data drive circuit and achieve the uniformity of brightness between pixels.

Driving method and circuit for automatic voltage output of active matrix organic light emitting device and data drive circuit using the same

A digital-to-analog converter comprises a current supplier, a current divider dividing current supplied from the current supplier into certain amounts, an inverter outputting inverted signals of input signals and non-inverted signals, a switch controlling a flow of the current divided into the certain amounts by the current divider according to the inverted signals and the non-inverted signals, and a current output block adding up the current divided into the certain amounts according to the non-inverted signals to output an analog signal. The digital-to-analog converter can be implemented on a small chip area with desired resolution.

High resolution digital-to-analog converter

Disclosed herein are a time division sampling digital to analog converter for a flat panel display, a method of implementing the digital to analog converter, and a data driver circuit using the digital to analog converter. The time division sampling digital to analog converter includes a timing signal generation means for generating timing signals, a data selection means for receiving n-bit digital data, dividing the n-bit digital data into k groups, and outputting the divided digital input data; k reference signal generation means for each outputting 2analog reference signals; a reference signal selection means for receiving the outputs of the reference signal generation means and outputting only 2analog reference signals selected according to a timing signal from the timing signal generation means; a multiplexer for outputting one of reference signals from the reference signal selection means using the n/k-bit digital data from the data selection means as a control input; and a sampling mode analog addition means for sampling and storing the output of the multiplexer according to a timing signal from the timing signal generation means.

Time division sampling digital to analog converter for driving flat panel display, method of implementing the same, and data driver circuit using the same

Disclosed herein is a divide-add circuit and a high-resolution Digital-to-Analog Converter (DAC) using the same. The DAC includes a plurality of DAC units and one or more divide-add circuit units. The plurality of DAC units performs Digital-Analog (DA) conversion on two or more segmented codes, into which an input digital code is segmented. The one or more divide-add circuit units is configured to be each composed only of capacitors and switches and to generate a final DA conversion output for the entire input digital code based on the voltages of the DAC units. Accordingly, a high resolution of more than ten bits can be implemented.

Divide-add circuit and high-resolution digital-to-analog converter using the same

The present invention relates to a catalyst system for preparing styrene polymer and a method of preparing styrene polymer using the same, more particularly to a catalyst system for preparing styrene polymer capable of preventing coagulation of polymer to the reactor by preventing gelation, offering high conversion ratio, simplifying polymer production and enabling product size control, and a method of preparing styrene polymer using the same.

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Hwasung, South Korea

Young-Suk Son