Pixel Sensing Circuit with ADC Sharing for Display Uniformity
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Solution Overview
Problem
Display devices, such as organic light emitting display devices and LCDs, face challenges in maintaining uniform picture quality due to characteristic deviations among pixels, which deteriorate over time, affecting the brightness and overall image quality.
Innovation Solution
A display device with a sensing unit to extract characteristic information of pixels, a compensating unit to set correction values based on digital sensing data, and a data driver to generate data signals that compensate for these deviations, ensuring uniform brightness across pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If pixels are manufactured with standard processes, then manufacturing cost and simplicity are maintained, but characteristic deviations among pixels occur causing non-uniform picture quality
Solution Approach 1:
The display device is divided into functional modules: sensing lines separate from data lines, sensing circuits at pixel-level to extract characteristic information, ADCs for analog-to-digital conversion, and compensating circuits for correction. This segmentation allows each module to perform its specific function independently, achieving precise pixel characterization without requiring complete redesign of the entire display system.
Solution Approach 2:
The sensing circuits extract characteristic information of pixels in advance during a sensing period before the actual display operation. This preliminary measurement of pixel characteristics (such as threshold voltage and mobility) allows the compensating circuit to pre-calculate correction values, which are then applied during data signal generation to ensure uniform picture quality from the start.
2Measurement precision
If characteristic information of all pixels is sensed individually, then measurement precision is improved, but sensing time and processing complexity increase
Solution Approach 1:
Multiple sensing lines are connected to a shared ADC (analog-to-digital converter) through switching elements. This allows the ADC to be reused across multiple sensing channels, converting analog characteristic information from different pixels sequentially. By merging the ADC resource, the number of separate ADC components is reduced, and the sensing operation is optimized to minimize the overall sensing period while maintaining individual pixel measurement precision.
Solution Approach 2:
The sensing operation is performed in a dedicated sensing period that is periodically allocated within the display device's operation cycle. During this sensing period, characteristic information of pixels is extracted through sensing lines, converted by ADCs, and processed to generate correction values. This periodic sensing approach separates measurement from display operations, allowing precise individual pixel characterization without continuously interrupting the display function.
3Manufacturing precision
If correction values are calculated for all pixels, then picture quality uniformity is improved, but data processing load and complexity increase
Solution Approach 1:
The sensing circuits measure actual pixel characteristics (such as threshold voltage and carrier mobility), and this measured information is fed back to the compensating circuit. The compensating circuit uses this feedback to calculate correction values that are then applied to the data signals before they reach the pixels. This closed-loop feedback mechanism ensures that picture quality uniformity is actively maintained by continuously compensating for pixel variations based on real measured data.
Solution Approach 2:
The compensating circuit changes the parameters of data signals (such as voltage levels or current magnitudes) based on the correction values derived from pixel characteristic measurements. By dynamically adjusting these electrical parameters, the system compensates for variations in pixel performance, ensuring that pixels with different inherent characteristics still produce uniform picture quality output.
Data Source
AI summary
A display device that may compensate for characteristic deviations among pixels and impact picture quality is provided. The display device includes a plurality of pixels, a plurality of sensing lines connected to the pixels, a sensing circuit configured to extract characteristic information of the pixels through the sensing lines. The sensing circuit includes a plurality of analog-to-digital converters (ADC) to convert the characteristic information into digital sensing data and to output the digital sensing data. A compensating circuit is configured to compare output values of the plurality of ADCs, to set a correction value, and to convert first data into second data based on the sensing data and the correction value. A data driver is configured to generate data signals corresponding to the second data and to output the data signals to the pixels.