Ambient Illuminance Sensor System with Hysteresis Filter

Solution Overview

Problem

Computing devices face challenges in managing screen brightness due to rapid changes in ambient illuminance levels, especially when a human is present and moving in environments with low and anisotropic light sources.

Innovation Solution

An ambient illuminance sensor system that includes a light sensor and a human presence sensor, which processes ambient illuminance values using a hysteresis filter when the illuminance level is low and a human is detected, to reduce sudden changes in screen brightness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the light sensor directly uses ambient illuminance values to adjust screen brightness, then the screen brightness responds quickly to light changes, but the screen brightness becomes unstable when a human is present and moving in low light environments

Engineering Contradiction:

Improveresponse speed of screen brightness adjustmentVSAvoidstability of screen brightness

Core Design Contradiction:

SpeedVSStability of the object's composition

Solution Approach 1:

The system dynamically adjusts the filtering characteristics of the hysteresis filter based on detected conditions. When a human is detected in low ambient light, the filter applies stronger smoothing to stabilize brightness. In other conditions, it applies minimal filtering to maintain quick response. This dynamic adaptation resolves the contradiction between fast response and stability.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the parameters of the brightness adjustment process based on environmental conditions. By modifying the hysteresis filter characteristics (thresholds, smoothing factors) according to ambient light levels and human presence detection, the system optimizes the balance between response speed and stability for different operating scenarios.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If a hysteresis filter is always applied to process ambient illuminance values, then the screen brightness becomes stable, but the response to actual light changes becomes delayed

Engineering Contradiction:

Improvestability of screen brightnessVSAvoidresponse speed of screen brightness adjustment

Core Design Contradiction:

Stability of the object's compositionVSSpeed

Solution Approach 1:

The system dynamically adjusts the filtering characteristics of the hysteresis filter based on detected conditions. When a human is detected in low ambient light, the filter applies stronger smoothing to stabilize brightness. In other conditions, it applies minimal filtering to maintain quick response. This dynamic adaptation resolves the contradiction between fast response and stability.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the parameters of the brightness adjustment process based on environmental conditions. By modifying the hysteresis filter characteristics (thresholds, smoothing factors) according to ambient light levels and human presence detection, the system optimizes the balance between response speed and stability for different operating scenarios.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If the system applies brightness adjustment based on raw ambient illuminance data, then the brightness adjustment is responsive, but the user experience deteriorates due to sudden brightness changes caused by human movement

Engineering Contradiction:

Improveresponsiveness of brightness adjustmentVSAvoiduser experience

Core Design Contradiction:

ProductivityVSEase of operation

Solution Approach 1:

The hysteresis filter acts as an intermediary between the light sensor and the display brightness control. It processes the raw illuminance values and human presence data to generate smoothed brightness adjustment commands. This intermediary filtering eliminates sudden brightness changes caused by human movement while preserving meaningful light level transitions, thereby improving user experience without completely sacrificing responsiveness.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system dynamically adjusts the filtering characteristics of the hysteresis filter based on detected conditions. When a human is detected in low ambient light, the filter applies stronger smoothing to stabilize brightness. In other conditions, it applies minimal filtering to maintain quick response. This dynamic adaptation resolves the contradiction between fast response and stability.

Inventive Principle:

Principle #15Dynamics

4Stability of the object's composition

If the system uses additional sensors and processing logic to detect human presence and apply filtering, then the screen brightness stability improves, but the device complexity increases

Engineering Contradiction:

Improvestability of screen brightnessVSAvoidcomplexity of sensor system and processing logic

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The system uses existing sensors (light sensor, proximity sensor, or camera) for multiple purposes. The light sensor serves both as an ambient light detector and as part of the hysteresis filtering mechanism. The proximity sensor or camera serves both as a human presence detector and can inform the filtering logic. This multi-functionality reduces the need for additional dedicated components, mitigating the complexity increase.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system uses its own existing resources (processing power, existing sensors) to solve the brightness stability problem rather than requiring entirely new dedicated components. The processor that already exists for other tasks is used to implement the hysteresis filter logic and human presence detection algorithms, allowing the system to serve itself and reducing overall device complexity.

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 system effectively reduces the impact of human movement on ambient illuminance readings, leading to more stable screen brightness adjustments and improved user experience, especially in environments with low and variable light conditions.

Implementation Method 1

a light sensor to generate a series of ambient illuminance values from an area surrounding a computing device

Methodology Applied

Scientific EffectPhotoelectric Effect: Photoelectric Effect

Implementation Method 2

a human presence sensor configured to detect presence of a human in vicinity of the computing device

Methodology Applied

Scientific EffectInfrared Detection: Infrared Radiation

Implementation Method 3

applying a hysteresis filter to process the series of ambient illuminance values

Methodology Applied

Scientific EffectHysteresis: Hysteresis

Data Source

PatentUS12205316B2Ambient illuminance sensor system

Publication Date: 2025.01.21 MICROSOFT TECHNOLOGY LICENSING LLC

AI summary

The ambient illuminance sensor system disclosed herein includes a light sensor to generate a series of ambient illuminance values from an area surrounding a computing device, a human presence sensor configured to detect presence of a human in vicinity of the computing device, and computer implemented instructions for determining ambient illuminance level (AIL) based on at least in part on the series of ambient illuminance values, determining presence of a human in vicinity of the light sensor, and based on at least in part on determining that the AIL is below a threshold and that a human is present, applying a hysteresis filter to process the series of ambient illuminance values.