Indirect Threshold Voltage Sensing in Electronic Displays

Solution Overview

Problem

As display resolutions increase, threshold voltage shifts among pixels in electronic displays lead to pixel non-uniformity and image quality degradation, making it challenging to compensate for varying threshold voltages across numerous pixels within limited processing time and memory constraints.

Innovation Solution

The implementation of indirect current or charge sensing techniques to determine threshold voltage values, allowing for compensation at the column level rather than individually, using existing display circuitry components to measure and adjust for shifts in threshold voltage, current, and voltage across pixels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If individual pixel-level threshold voltage compensation is implemented, then image quality is improved, but processing time and memory requirements increase significantly

Engineering Contradiction:

Improvethreshold voltage measurement precisionVSAvoidprocessing time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent segments the display panel into column groups, where each group shares common sensing and compensation circuitry. Instead of measuring each pixel individually, multiple pixels within a column group are measured using shared circuit resources, thereby reducing the overall processing time while maintaining adequate measurement precision for compensation purposes.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements universal sensing and compensation circuitry that serves multiple pixels within a column group. The same sensing circuit and compensation logic are reused across multiple pixels, eliminating the need for dedicated individual circuitry per pixel and significantly reducing processing overhead.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Measurement precision

If individual pixel-level threshold voltage compensation is implemented, then image quality is improved, but memory availability is reduced

Engineering Contradiction:

Improvethreshold voltage measurement precisionVSAvoidmemory availability

Core Design Contradiction:

Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent segments the display panel into column groups, where each group shares common sensing and compensation circuitry. Instead of measuring each pixel individually, multiple pixels within a column group are measured using shared circuit resources, thereby reducing the overall processing time while maintaining adequate measurement precision for compensation purposes.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements universal sensing and compensation circuitry that serves multiple pixels within a column group. The same sensing circuit and compensation logic are reused across multiple pixels, eliminating the need for dedicated individual circuitry per pixel and significantly reducing processing overhead.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Productivity

If column-level compensation is implemented, then processing time is reduced, but measurement precision may be reduced

Engineering Contradiction:

Improveprocessing speedVSAvoidthreshold voltage measurement precision

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent applies partial compensation by targeting column groups rather than individual pixels. This partial action approach accepts some loss in measurement precision compared to full individual pixel compensation, but achieves significant gains in processing speed and productivity.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS10573209B2Systems and methods for indirect threshold voltage sensing in an electronic display

Publication Date: 2020.02.25 APPLE INC

AI summary

An electronic device includes a display panel with pixels arranged in at least one row and at least one column. The electronic device also includes a sensing channel coupled to the at least one column. The sensing channel indirectly calculates a threshold voltage of the plurality of pixels based on an application of a first current level and a second current level to a data line of a first column of the at least one column of the pixels.