Display Aging Compensation via Ambient Light Sensor

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Solution Overview

Problem

Electronic devices with displays face challenges in accurately predicting and compensating for aging-induced changes in display characteristics, such as color shifts and intensity variations, due to factors like operating temperature, ambient light, and usage duration, which affect the consistency of display performance over time.

Innovation Solution

Incorporating an ambient light sensor to periodically measure display light emissions, allowing control circuitry to discriminate between ambient and display light contributions, and using predetermined image sequences to gather gamma curves and compensate for aging effects, ensuring consistent display output.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If display pixels are monitored continuously to detect aging effects, then measurement precision is improved, but use of energy increases and productivity decreases

Engineering Contradiction:

Improvedisplay aging detection accuracyVSAvoidenergy consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The system performs display light measurements periodically at predetermined time intervals rather than continuously. The control circuitry is configured to make display light measurements at predetermined time intervals, which reduces energy consumption while still detecting aging effects over time.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system performs measurements during display initialization and before normal display operations begin. This preliminary characterization establishes baseline gamma curves and display properties, enabling subsequent aging detection without requiring continuous measurements during normal operation.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If display light measurements are made during normal content display, then productivity is maintained, but measurement precision decreases due to ambient light interference

Engineering Contradiction:

Improvedisplay operation continuityVSAvoiddisplay light measurement accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The system separates display light measurements from ambient light by using display light that is modulated at a frequency different from ambient light. The control circuitry extracts display light contributions from ambient light measurements by analyzing frequency components, thereby isolating the display signal from environmental interference.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The system modulates display light at specific frequencies to create a distinguishable signal. By varying display light intensity at known frequencies and detecting these frequency components in sensor readings, the system can differentiate display light from ambient light even during normal operation.

Inventive Principle:

Principle #18Mechanical vibration

3Measurement precision

If display pixels are modulated at high frequency to separate display light from ambient light, then measurement precision is improved, but device complexity increases

Engineering Contradiction:

Improveambient light discrimination accuracyVSAvoidcontrol circuitry complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The control circuitry uses existing display driver circuitry to modulate pixel outputs for measurement purposes. The same display controllers that drive normal content also perform the modulated display light generation, eliminating the need for separate dedicated measurement hardware and reducing overall system complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system combines ambient light sensing and display light measurement functions into a single sensor readout process. The ambient light sensor simultaneously captures both ambient light and modulated display light, and the control circuitry processes both functions through unified signal processing algorithms.

Inventive Principle:

Principle #5Merging (Combining)

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 solution enables dynamic adjustments to display brightness and color based on ambient conditions and compensates for aging-induced degradation, maintaining consistent display performance and user experience over the device's lifetime.

Implementation Method 1

a light sensor may be used to periodically measure display light that is emitted by the display

Methodology Applied

Scientific EffectLight detection: Photoelectric Effect

Data Source

PatentUS11798460B2Electronic devices with display aging compensation

Publication Date: 2023.10.24 APPLE INC

AI summary

An electronic device may have a display. The display may have light-emitting diode pixels or other pixels. Due to aging-induced degradation of the pixels, the output intensity and color of the pixels may vary over the lifetime of the display. Control circuitry in the device may use an ambient light sensor to measure ambient light and stray display light. The display light measurements may be used in monitoring aging effects so that the control circuitry can compensate for aging-induced pixel degradation. Display light measurements may be made over a sequence of image frames. The image frames in the sequence of frames may include white and black frames or frames of different colors interleaved with black frames. Different frame intensities may be used during measurements of stray display light to gather gamma curves for the display.