Ambient Light Load Control With Dynamic Turn-Off Thresholds

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Solution Overview

Problem

Ambient light sensors in load controllers are affected by the light emitted from the controlled lighting load, leading to constant on/off cycling and inaccurate light control due to artificially high ambient light readings.

Innovation Solution

Adjust the turn-off threshold based on the ambient light level after a predetermined time following the switching on of the lighting load, using the then-current ambient light level to set an appropriate threshold for turning off the lighting load, thereby avoiding undesired cycling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the ambient light sensor is positioned to detect ambient light levels, then the controller can determine when to switch the lighting load on and off, but the light emitted from the lighting load impacts the sensor reading and causes artificially high ambient light levels

Engineering Contradiction:

Improveambient light level measurement accuracyVSAvoidartificially high ambient light reading

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The patent applies preliminary action by measuring the ambient light level at a specific moment in time - immediately when the lighting load is switched on. This timing captures the baseline ambient light level before the load's emitted light significantly impacts the sensor reading. By establishing this baseline measurement at the optimal moment, the system can then dynamically adjust the turn-off threshold to compensate for the load's light contribution, resolving the measurement accuracy problem.

Inventive Principle:

Principle #10Preliminary action

2Device complexity

If a fixed turn-off threshold is used, then the control logic is simple, but the lighting load cycles on and off constantly due to the sensor detecting artificially high ambient light levels

Engineering Contradiction:

Improvecontrol logic simplicityVSAvoidstable lighting control

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent applies dynamics by transitioning from a static, fixed turn-off threshold to a dynamic threshold that automatically adjusts based on measured ambient light conditions. The turn-off threshold is set as a function of the measured ambient light level when the load is switched on, plus a predetermined offset. This dynamic adjustment ensures the threshold adapts to varying environmental lighting conditions while compensating for the load's own emitted light, preventing constant cycling and improving control reliability.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements feedback by using the ambient light sensor to continuously monitor lighting conditions and automatically adjusting the turn-off threshold based on these measurements. The system measures the ambient light level when the load is on, uses this measurement to calculate an appropriate turn-off threshold, and then applies this threshold for subsequent control decisions. This closed-loop feedback mechanism eliminates the need for manual threshold tuning and prevents oscillation.

Inventive Principle:

Principle #23Feedback

3Measurement precision

If the ambient light sensor reads the light level immediately after switching on the load, then the reading includes the load's emitted light, but waiting longer allows the true ambient light level to be measured

Engineering Contradiction:

Improvetrue ambient light level detectionVSAvoiddelay in threshold adjustment

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent applies preliminary action by performing the ambient light measurement at the optimal moment - immediately when the lighting load is switched on. This timing captures the baseline ambient light level before the load's emitted light significantly impacts the sensor reading. By establishing this baseline measurement at the optimal moment, the system can then dynamically adjust the turn-off threshold to compensate for the load's light contribution, resolving the measurement accuracy problem.

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

Prevents constant on/off cycling by ensuring the turn-off threshold is set appropriately, aligning with the true ambient light conditions, thus maintaining stable lighting control.

Implementation Method 1

a sensor configured to sense ambient light levels in the environment

Methodology Applied

Scientific EffectPhotoelectric Effect: Photoelectric Effect

Data Source

PatentUS12538404B2Dynamic thresholding for ambient light-based load control

Publication Date: 2026.01.27 LEVITON MFG CO INC

AI summary

Approaches for controlling supply of power to a load in an environment based on ambient light sensing and dynamic thresholding include, based on an ambient light level in the environment decreasing to a turn-on threshold light level, controlling a switch of an electrical load controller to couple the supply of electrical power to the lighting load, sensing a current ambient light level in the environment after lapse of a predetermined amount of time subsequent to controlling the switch to couple the supply of electrical power to the lighting load, and adjusting a turn-off threshold light level using the current ambient light level.