Display Panel Sensing Noise Mitigation via Differential Methods
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Solution Overview
Problem
Electronic displays with higher resolutions and pixel densities face interference from common-mode noise, such as electromagnetic interference, which complicates display panel sensing and image fidelity, especially in portable devices.
Innovation Solution
The use of differential sensing (DS), difference-differential sensing (DDS), correlated double sampling (CDS), and programmable integration capacitance to mitigate noise in display panel sensing, allowing for more precise image compensation by subtracting common-mode and temporal noise from the test signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If single-ended display panel sensing is used, then device complexity is reduced, but measurement precision deteriorates due to substantial noise detection in high pixel density displays
Solution Approach 1:
The sensing system is segmented into two separate sensing paths: one for sensing the test pixel signal and another for sensing the common-mode noise signal. This segmentation allows the system to separately measure and then subtract the noise component from the test signal, improving measurement precision without requiring a complete redesign of the sensing architecture.
Solution Approach 2:
A reference pixel is introduced as an intermediary element that captures only the common-mode noise present on the sense line. This reference pixel acts as a mediator between the noise source and the test pixel, enabling the system to isolate and remove the noise component through differential processing.
2Manufacturing precision
If display resolution and pixel density are increased, then image fidelity is improved, but noise from common-mode interference increases, worsening measurement precision
Solution Approach 1:
The common-mode noise component is extracted from the test pixel signal through differential sensing. By measuring the noise separately using a reference pixel and then subtracting it from the test signal, the system removes the harmful noise component while preserving the useful test signal, thereby maintaining sensing precision despite high pixel density.
Solution Approach 2:
The common-mode noise that normally degrades sensing precision is converted into a useful reference signal. By intentionally measuring the noise through a reference pixel, the system transforms the harmful interference into a compensatable component that can be subtracted from the test signal, improving overall measurement accuracy.
3Measurement precision
If differential sensing is implemented, then measurement precision is improved by removing common-mode noise, but device complexity increases
Solution Approach 1:
Existing display pixels are made multi-functional by using them both as test pixels for sensing display characteristics and as reference pixels for noise measurement. This universality allows the system to perform both sensing functions using the same pixel array infrastructure, reducing the need for additional dedicated hardware and thereby limiting the increase in device complexity.
Solution Approach 2:
The sensing operation is performed periodically by programming pixels with test data at specific time intervals. This periodic action allows the system to reuse the same pixels for both test and reference measurements at different times, reducing hardware complexity while maintaining measurement precision through temporal separation of sensing functions.
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
These methods effectively reduce noise in display panel sensing, improving the signal-to-noise ratio and image fidelity by accounting for system-level and temporal noise, thereby enhancing the quality of images displayed on electronic devices.
Implementation Method 1
differentially sensing the test pixel in comparison to the reference pixel results in at least some of the common-mode noise subtracted away from the signal of the test pixel
Implementation Method 2
the integration capacitors may be programmed to have the same ratio as the ratio of capacitances on the sense lines. This may account for noise due to sense line capacitance mismatch
Data Source
AI summary
Systems and methods are provided for differential sensing (DS), difference-differential sensing (DDS), correlated double sampling (CDS), and/or programmable capacitor matching to reduce display panel sensing noise. An electronic device may include one or more processors and an electronic display. The one or more processors may generate image data and adjust the image data based at least in part on display sensing feedback. The electronic display may employ sensing circuitry that obtains the display sensing feedback at least in part by applying test data to a pixel of a column of an active area of the display and differentially senses an electrical value of the pixel in comparison to a reference signal from a different column. This reference signal may provide a common mode noise reference, which is removed by the differential sensing and thereby enhances a quality of the sensed electrical value of the pixel.