OLED Pixel Driving Method for Luminance and Power Trade-off
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Solution Overview
Problem
As the size of active matrix OLED display devices increases and resolution improves, the scanning period for writing image data lengthens, reducing the light emitting period and resulting in decreased average luminance, which can be mitigated by increasing the power source voltage but at the cost of increased power consumption.
Innovation Solution
The implementation of a display device with a pixel structure comprising multiple transistors and capacitors, allowing for a scanning period and light emitting period to temporally overlap, enabling efficient data storage and emission, and a driving method that includes specific signal applications to optimize the light emitting period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the scanning period is increased to write image data for larger display sizes and higher resolution, then the display size and resolution are improved, but the light emitting period is reduced resulting in decreased average luminance
Solution Approach 1:
The patent applies preliminary action by storing image data in capacitors during the scanning period before the light emitting period begins. This allows the data to be prepared in advance, enabling the light emitting period to maintain sufficient duration even as the scanning period increases with larger display sizes and higher resolution.
2Illumination intensity
If the power source voltage is increased to increase the average luminance of the image, then the average luminance is improved, but the power consumption is increased
Solution Approach 1:
The patent changes the timing parameters of the driving scheme by allowing the scanning period and light emitting period to overlap. This temporal reorganization enables sufficient light emitting duration without increasing power source voltage, thereby maintaining average luminance while avoiding increased power consumption.
3Area of stationary object
If the scanning period is increased to write image data for larger display sizes, then the display size is improved, but the light emitting period is reduced resulting in decreased average luminance
Solution Approach 1:
The patent applies preliminary action by storing image data in capacitors during the scanning period before the light emitting period begins. This allows the data to be prepared in advance, enabling the light emitting period to maintain sufficient duration even as the scanning period increases with larger display sizes and higher resolution.
Solution Approach 2:
The patent implements continuity of useful action by overlapping the scanning period and light emitting period. The light emitting action continues uninterrupted while data scanning occurs in parallel, ensuring that the light emitting period duration is maintained regardless of increased display size.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration ensures a sufficient light emitting period in each frame, allowing for larger display sizes and higher resolution stereoscopic images without significantly increasing power consumption.
Implementation Method 1
The organic light emitting diode (OLED) includes an anode layer and a cathode layer which generate an electric field and an organic light emitting material which emits light due to the electric field.
Data Source
AI summary
A method of driving an OLED display includes: during a scanning period of a first frame, turning off a relay transistor and turning on a switching transistor to enable a second data voltage applied to a data line to be stored in a first capacitor; and during a light emitting period of the first frame, performing an operation to turn on a light emitting transistor and a compensation transistor to enable a voltage into which a first data voltage and a threshold voltage of a driving transistor are reflected to be applied to a second node for enabling the OLED to emit light by a driving current which flows into a driving transistor. The scanning period and the light emitting period temporally overlap each other.