Display Screen Transmittance Correction for Ambient-Light Detection

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Solution Overview

Problem

Existing terminal devices face issues with inaccurate ambient light detection due to changes in screen light transmittance caused by aging, affecting display brightness adjustment.

Innovation Solution

A display device with a first light sensor at the back side of the screen to detect ambient light, a light source at the front side of the screen edge to emit light, and a second light sensor at the back side to detect the light source brightness, allowing for real-time correction of light transmittance and accurate ambient light detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the light sensor is disposed below the screen to detect ambient light, then the terminal device can adjust display brightness according to ambient light intensity, but the light transmittance of the screen changes with aging causing inaccurate ambient brightness information

Engineering Contradiction:
Improveambient light detection accuracyVSAvoiddetection accuracy stability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

A light guide structure is introduced as an intermediary component between the light source and the light sensor. This light guide transmits light from the light source through the screen to the light sensor, enabling indirect measurement of screen light transmittance. By using this intermediary, the system can detect changes in screen aging without requiring direct access to the screen's optical properties, thus resolving the contradiction between maintaining detection accuracy and accounting for aging effects.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The system implements a feedback mechanism where the light sensor continuously monitors the light transmittance of the screen by detecting light from the light source. Based on this feedback, the processor calculates the actual light transmittance and compensates for aging effects in real-time. This closed-loop feedback system ensures that ambient light detection remains accurate despite screen aging, resolving the contradiction between measurement precision and reliability over time.

Inventive Principle:
Principle #23Feedback

2Measurement precision

If a light transmittance calibration step is performed during production, then accurate ambient light detection can be achieved, but production costs and process complexity increase

Engineering Contradiction:
Improveambient light detection accuracyVSAvoidproduction process simplicity
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The system performs self-calibration by automatically detecting screen light transmittance using the light source and light sensor during production. The processor automatically calculates calibration parameters based on detected light intensities without requiring manual intervention or external calibration equipment. This self-service approach achieves accurate ambient light detection while simplifying the manufacturing process, resolving the contradiction between measurement precision and ease of manufacture.

Inventive Principle:
Principle #25Self-service

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

The solution provides more accurate ambient light detection, reducing the impact of screen aging on brightness adjustment and eliminating the need for a light transmittance calibration step in production, thereby lowering costs.

Implementation Method 1

a first light sensor disposed at a back side of the display screen body and configured to detect a brightness of ambient light

Methodology Applied
Scientific EffectPhotoelectric Effect: Photoelectric Effect

Implementation Method 2

a light source disposed at a front side of the display screen edge part and configured to emit light according to a preset brightness

Methodology Applied
Scientific EffectLight Emitting Diode: Light Emitting Diode

Implementation Method 3

a second light sensor disposed at a back side of the display screen edge part and configured to detect a brightness of the light source

Methodology Applied
Scientific EffectPhotoelectric Effect: Photoelectric Effect

Data Source

PatentEP4343749B1Display device, detection method for ambient light, electronic device and storage medium
Publication Date: 2025.10.29 BEIJING XIAOMI MOBILE SOFTWARE CO LTD
  • EP4343749B1 patent drawingFigure 1~2
  • EP4343749B1 patent drawingFigure 3~4
  • EP4343749B1 patent drawing

AI summary

A display device includes: a display screen (100) including a display screen body (112) and a display screen edge part (115), at least one edge of the display screen (100) being bent toward a back side of the display screen (100) to form the display screen body (112) and the display screen edge part (115); a first light sensor (101) disposed at a back side of the display screen body (112) and configured to detect a brightness of ambient light of a front side of the display screen body (112); a light source (102) disposed at a front side of the display screen edge part (115) and configured to emit light according to a preset brightness; and a second light sensor (103) disposed at a back side of the display screen edge part (115) and configured to detect a brightness of the light source (102).