OLED Display Multipixel Sensing for Low Gray Level Compensation
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Solution Overview
Problem
Existing OLED displays face challenges in accurately sensing and compensating for changes in driving properties of pixels, particularly at low gray levels, due to decreased sensing current, which affects image quality and uniformity.
Innovation Solution
The implementation of a multipixel sensing method that shares sensing paths among subpixels, allowing for simultaneous sensing of driving properties across blocks, and a compensation circuit that adjusts property values based on adjacent blocks to identify and correct defective pixels, thereby stabilizing image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single pixel sensing method is used, then individual pixel properties can be sensed, but sensing current decreases at low gray levels making accurate sensing difficult
Solution Approach 1:
The patent combines multiple pixels (e.g., 2N pixels) into a single sensing unit that shares common sensing paths. By merging the sensing currents of multiple pixels, the total sensing current is increased, enabling accurate sensing even at low gray levels where individual pixel currents would be too weak. This is achieved through time-division multiplexing where multiple pixels are sensed simultaneously through shared sensing paths.
2Measurement precision
If sensing paths are shared among multiple pixels, then sensing current increases improving measurement accuracy, but device complexity increases due to multiplexing control
Solution Approach 1:
The patent employs time-division multiplexing where pixels are sensed in periodic cycles. During specific time periods, different groups of pixels are selectively connected to sensing paths through switching elements. This periodic switching allows multiple pixels to share sensing resources sequentially, increasing effective sensing current while managing circuit complexity through structured time-multiplexed control.
Solution Approach 2:
The sensing paths and associated circuitry are designed to serve multiple pixels simultaneously through time-division multiplexing. The same sensing amplifier, ADC, and processing circuitry are universally utilized across multiple pixel groups, reducing the need for dedicated sensing circuits for each pixel and thereby managing device complexity while maintaining enhanced sensing capability.
3Reliability
If individual pixel compensation is implemented, then image quality improves, but memory storage requirements increase significantly
Solution Approach 1:
The patent combines multiple pixels into sensing blocks and performs sensing and compensation at the block level rather than individual pixel level. By merging the sensing results of multiple pixels within a block, the compensation data required is reduced proportionally. For example, if 2N pixels share sensing paths, only N sensing values are generated, significantly reducing memory storage requirements while maintaining image quality through block-level compensation.
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 approach enables stable sensing of driving properties at low gray levels, improves image quality by compensating for variations in pixel properties, and reduces memory storage requirements, effectively addressing the limitations of current sensing methods.
Implementation Method 1
Each OLED includes an anode, a cathode, and an organic compound layer formed between the anode and the cathode... When a driving voltage is applied to the anode and the cathode, holes passing through the hole transport layer HTL and electrons passing through the electron transport layer ETL move to the emission layer EML and form excitons. As a result, the emission layer EML generates visible light.
Data Source
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Figure 3A~3B
AI summary
An organic light emitting diode display and a method for driving the same are disclosed. The organic light emitting diode display includes a display panel including data lines and gate lines crossing each other, and blocks each including a plurality of subpixels and sensing paths. Each of the plurality of sensing paths in each block are shared by the plurality of subpixels included in each block, and a data driver supplies a sensing data voltage to each subpixel through the data lines and outputs a sensing value of each block obtained through the sensing path. A data modulator selects a compensation value of each block based on the sensing value of each block, and modulates data of an input image using the compensation value. The modulated data of the input image is then transmitted to the data driver. Further, when a high level grey level is supplied to the subpixels, a block comprising a dark spot bad subpixel may be detected based upon the sensing values of a target block and blocks adjacent the target block. Conversely when a low level grey level is supplied, a bright spot bad subpixel may be detected in a target block.