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

• US 20060290621A1
• Filed: 03/03/2006
• Published: 12/28/2006
• Est. Priority Date: 06/28/2005
• Status: Active Grant

• Current Assignee: i-KAIST Co., Ltd.
• Original Assignee: Korea Advanced Institute of Science and Technology
• Inventors: Son, Young-Suk, Cho, Gyu-Hyeong, Kim, Sang-Kyung
• Granted Patent: US 7,605,792 B2
• Time in Patent Office: Days
• US Class Current: 345/82
• CPC Class Codes: G09G 2300/0857 Static memory circuit, e.g. flip-flop
• CPC Class Codes: G09G 2310/066 Waveforms comprising a gently increasing or decreasing portion, e.g. ramp
• CPC Class Codes: G09G 3/2014 by modulation of the duration of a single pulse during which the logic level remains constant
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element

Abstract

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.

Claims

1. A driving method for automatic voltage output of an Organic Light Emitting Device (OLED), comprising the steps of:

sensing a writing state of current via a data line when writing current via the data line of display pixels using sweep voltage signals; and

outputting control signals to the respective pixels based on amounts of the current sensed in real time, thereby driving the pixels at intended current levels.

2. A driving circuit for automatic voltage output of an OLED, comprising:

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.

3. The circuit as set forth in claim 2, wherein the comparison means is constructed to operate in voltage mode when the reference signal is a voltage type.

4. The circuit as set forth in claim 2, wherein the comparison means is constructed to operate in current mode when the reference signal is a current type.

5. The circuit as set forth in claim 2, wherein the data writing start/end control signal generation means includes a logical circuit, which is activated when a set terminal thereof is set in response to the output of the timing generation means, and a reset terminal of which is controlled in response to the output of the comparison means.

6. The circuit as set forth in claim 2, further comprising reference signal generation means for generating the reference signal which is input to the comparison means, the reference signal generation means comprising a Digital-to-Analogue Converter (DAC) for converting an n-bit digital data input to an analogue signal.

7. A data drive circuit to which the drive circuit of claim 2 is applied, wherein, when reference signals of respective channels are current signals, the respective channels generate reference current signals depending on n-bit digital data inputs of the respective channels, and current drive levels of pixels are set to the respective reference current signal levels.

8. A data drive circuit to which the drive circuit of claim 2 is applied, wherein, when reference signals of respective channels are voltage signals, outputs of a reference common voltage source, having a plurality of outputs, are selected by the channels and then the reference signals of the channels are independently selected.