Current Integrator Offset Compensation for OLED Sensing
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Solution Overview
Problem
Conventional external compensation methods for organic light-emitting displays face challenges in achieving accurate sensing and compensation due to large dispersion in integral values caused by offset voltages among current integrators, leading to unreliable pixel compensation.
Innovation Solution
A current integrator with a swapping part that alternates the path of current and reference voltage, combined with sample & hold circuits and an analog-to-digital converter, to compensate for offset voltage variations and improve sensing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional external compensation method is used with current integrators, then sensing function is provided, but large dispersion in integral values occurs due to offset voltages among integrators
Solution Approach 1:
The patent applies feedback by measuring the offset voltage of each current integrator and using this information to correct the integral values. The offset voltage measurement circuit measures the offset voltage of each integrator, and the timing controller uses this feedback to compensate for variations in electrical characteristics, thereby improving sensing accuracy and compensation reliability.
Solution Approach 2:
The patent changes the parameter being measured from just the integral value to include both the integral value and the offset voltage. By measuring and utilizing the offset voltage parameter, the system can correct for integrator variations and improve the reliability of the compensation process.
2Productivity
If multiple sensing lines with separate amplifiers are used, then each pixel can be sensed, but offset voltage variations among amplifiers cause large dispersion in sensed values
Solution Approach 1:
The timing controller receives offset voltage information from each amplifier and uses this feedback to correct the sensed values. This allows multiple pixels to be sensed simultaneously while compensating for amplifier variations, maintaining high productivity while improving measurement precision.
3Reliability
If internal compensation is implemented to compensate for threshold voltage variations, then pixel brightness uniformity improves, but pixel circuit configuration becomes complicated
Solution Approach 1:
The patent introduces an intermediary approach by using a current integrator as a mediator between the pixel circuit and the timing controller. The integrator accumulates the current from multiple pixels and converts it to a voltage signal, which is then processed by the timing controller. This external compensation method achieves brightness uniformity without complicating the pixel circuit configuration.
Data Source
AI summary
An organic light-emitting display can include a display panel including sensing lines connected to pixels; a current integrator configured to receive current from a pixel through a sensing line connected to a first input terminal, receive a reference voltage through a reference voltage line connected to a second input terminal, and swap a path through which the current applied through the first input terminal flows and a path through which the reference voltage applied through the second input terminal is supplied; a sampling part including a first sample and hold circuit for sampling a first output voltage of the current integrator and a second sample and hold circuit for sampling a second output voltage of the current integrator, subsequent to the first output voltage, which outputs the first and second output voltages sampled by the first and second sample and hold circuits simultaneously through a single output channel.