Common-Mode Noise Compensation in Display Sensing
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Solution Overview
Problem
Existing display technologies face challenges in fully compensating for external common-mode noise, which can lead to erroneous correction values and compromised non-uniformity compensation due to capacitively coupled fluctuations in local supply voltage, especially when filtering methods fail to account for parasitic capacitance mismatches between sensing channels.
Innovation Solution
A dual-channel sensing approach is employed, where a nearby pixel is sensed through an observation channel while keeping the pixel emission off, with sensed parameter values scaled according to the relative mismatches between sensing and observation channels, determined through an initial calibration process, to calculate a compensated sensing value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If filtering methods are used to reduce noise at each pixel, then non-uniformity compensation is improved, but external common-mode noise and error sources are missed leading to erroneous correction values
Solution Approach 1:
The patent divides the noise compensation function into two independent parts: (1) pixel-level filtering for non-uniformity compensation, and (2) channel-level common-mode noise sensing using observation channels. This segmentation allows each part to address specific noise sources without interfering with the other, resolving the contradiction between improving non-uniformity compensation and avoiding erroneous correction values.
Solution Approach 2:
The patent introduces observation channels as intermediary sensing paths that do not drive pixel emissions but specifically sense common-mode noise. These observation channels act as mediators between the power supply noise and the pixel sensing channels, allowing common-mode noise to be detected and subtracted without affecting the primary pixel display function.
2Measurement precision
If sensing channels are used to detect pixel current, then pixel parameter measurement is achieved, but parasitic capacitance mismatches cause common-mode errors
Solution Approach 1:
The patent creates copies of the pixel circuitry in observation channels that replicate the sensing function without the emission function. These copied channels sense the same common-mode noise affecting the original channels but without driving pixels, allowing the common-mode component to be isolated and removed from the measurement.
Solution Approach 2:
The patent implements a feedback mechanism where the sensed common-mode noise from observation channels is subtracted from the pixel channel measurements. This feedback loop continuously compensates for common-mode errors, maintaining measurement precision despite parasitic capacitance mismatches.
3Reliability
If observation channels are used to sense common-mode noise, then noise compensation is improved, but additional sensing channels increase device complexity
Solution Approach 1:
The patent designs observation channels with multi-functionality: they can sense common-mode noise when not driving pixels, and can be switched to drive pixels when needed. This universal design reduces the need for completely separate dedicated noise sensing circuitry, thereby reducing overall device complexity while maintaining noise compensation capability.
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 method effectively reduces common-mode errors by accurately accounting for channel mismatches, improving display panel uniformity and reducing noise-related inaccuracies in pixel current compensation.
Implementation Method 1
capacitively coupled fluctuations in local supply voltage resulting in a common-mode error
Data Source
AI summary
Electronic devices and methods for compensating for noise in a display that includes sensing a current in a sensing channel of the display. Compensating for the noise also includes sensing an observation current from noise in an observation channel of the display and scaling the observation current to generate a scaled observation current. The scaled observation current is subtracted from the sense current to generate a compensated output. The compensated output is used to drive compensation operations of the display based at least in part on the compensated output to reduce effects of the noise.