1. Field
Embodiments relate to a display device and a driving method thereof. More particularly, embodiments relate to an organic light emitting diode (OLED) display and a driving method thereof.
2. Description of the Related Art
A display device includes a plurality of pixels arranged on a substrate in the form of a matrix, defining a display area. Scan and data lines are connected to the respective pixels. Data signals are selectively applied to the pixels to display desired images. Display devices can be classified as passive and active matrix types, depending upon the method of driving the pixels. In view of resolution, contrast, and response time, the trend is towards the active matrix type where the respective unit pixels are selectively turned on or off.
Display devices may be used as display units for personal computers, portable phones, personal digital assistants (PDAs), other mobile information devices, or as a monitor for various kinds of information systems. A liquid crystal panel-based LCD, an organic electroluminescent display using an organic light emitting element, a plasma panel-based PDP, etc., are well known. Various kinds of emissive display devices, which are lighter in weight and smaller in volume than CRTs, have been recently developed. Organic light emitting diode displays are receiving much attention as a result of their emissive efficiency, luminance, viewing angle, and fast response time.
Organic electroluminescent displays may be driven using a passive matrix method or an active matrix method. With the passive matrix method, the organic light emitting elements are formed between anode lines and cathode lines that perpendicularly cross each other, and are driven by selecting the respective lines. With the active matrix method, a thin film transistor (TFT) and a capacitor are integrated into each pixel, and the organic light emitting elements are driven according to a voltage maintained by capacitance of the capacitor. With the active matrix method, a constant current can flow to the organic light emitting element when the thin film transistor operates in a saturation region. A source-drain voltage of the thin film transistor is determined by a driving voltage applied to an organic light emitting diode (OLED). However, the driving voltage applied to the OLED is changed in accordance with deterioration and temperature of the OLED. Therefore, a predetermined margin is set when the driving voltage is applied in an attempt to operate the thin film transistor with a constant current source even though the driving voltage of the OLED changes. The margin causes unnecessary power consumption.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.
USPTO Backgrounds
USPTO Backgrounds