Ambient Light Sensor Timing for High Display Ratio

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Solution Overview

Problem

The increasing demand for higher screen display ratios in mobile devices poses a challenge for determining ambient light intensity, as traditional methods require a frame with a certain width to prevent screen display light from affecting the photosensitive element, thereby compromising the screen display ratio.

Innovation Solution

A method for determining ambient light intensity that involves setting a light sensing collecting time window and sampling frequency based on the screen blanking time, allowing the photosensitive element to collect light intensity during screen blanking periods without the need for a frame, thus enabling the placement of the photosensitive element at the bottom of the screen to improve the screen display ratio.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a frame with a certain width is set within the field of view of the photosensitive element to prevent screen display light from being received, then the ambient light intensity determination accuracy is improved, but the screen display ratio deteriorates

Engineering Contradiction:
Improveambient light intensity determination accuracyVSAvoidscreen display ratio
Core Design Contradiction:
Measurement precisionVSArea of stationary object

Solution Approach 1:

The patent transitions from spatial separation (using a frame structure in the horizontal dimension) to temporal separation (using different time windows for light collection). By collecting light during screen blanking periods instead of during display periods, the system eliminates the need for a physical frame while maintaining measurement accuracy.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent utilizes the periodic blanking of the screen display to periodically collect ambient light measurements. The light sensing collecting time window is synchronized with the screen blanking periods, creating a periodic measurement cycle that avoids screen light interference without requiring structural modifications.

Inventive Principle:
Principle #19Periodic action

2Area of stationary object

If the photosensitive element is placed at the bottom of the screen to improve screen display ratio, then the screen display ratio is improved, but screen display light interferes with ambient light detection

Engineering Contradiction:
Improvescreen display ratioVSAvoidscreen light interference
Core Design Contradiction:
Area of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The system exploits the periodic blanking behavior of the screen display. During blanking periods when the screen is not emitting light, the photosensitive element collects ambient light without interference. This temporal multiplexing allows the photosensitive element to be positioned at the bottom of the screen while maintaining detection accuracy.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent performs preliminary identification of screen blanking periods before conducting light measurements. By determining the blanking time window in advance and synchronizing the light sensing collecting time window with these periods, the system proactively prevents screen light interference from affecting the ambient light detection.

Inventive Principle:
Principle #10Preliminary action

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 approach allows for accurate determination of ambient light intensity without the interference of screen light leakage, eliminating the need for a frame and thereby enhancing the screen display ratio of mobile devices.

Implementation Method 1

a photosensitive element is placed on a frame portion of a screen of a mobile terminal

Methodology Applied
Scientific EffectPhotoelectric Effect: Photoelectric Effect

Data Source

PatentEP3812720B1Method and apparatus for determining ambient light intensity and storage medium
Publication Date: 2025.04.16 BEIJING XIAOMI MOBILE SOFTWARE CO LTD
  • EP3812720B1 patent drawingFigure 1
  • EP3812720B1 patent drawingFigure 2~4
  • EP3812720B1 patent drawingFigure 5

AI summary

A method for determining ambient light intensity includes: acquiring a plurality of light sensing integral values obtained by sampling light intensity with a predetermined light sensing collecting time window and a predetermined sampling frequency through a photosensitive element, wherein the light sensing collecting time window is greater than a screen blanking time of a terminal; determining a minimum light sensing integral value and a maximum light sensing integral value in the plurality of light sensing integral values; determining a light sensing integral value of a photosensitive element which corresponds to an ambient light according to the maximum light sensing integral value, the light sensing collecting time window, the minimum light sensing integral value and the screen blanking time; and determining the ambient light intensity according to the light sensing integral value of the photosensitive element which corresponds to the ambient light and a predetermined light intensity.