Optical Sensor Circuit for Accurate CCT Measurement
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Solution Overview
Problem
Existing optical sensor circuits for luminaries face challenges in accurately measuring correlated color temperature (CCT) due to the influence of ambient light, leading to incorrect color point positioning and CCT value calculations, especially in environments with multiple strong light sources.
Innovation Solution
An optical sensor circuit with a controller unit and a clock that processes sensor signals differently based on high and low states of a clocked control signal, allowing for simultaneous measurement of light emitted by LEDs and ambient light using a single optical sensor, enabling accurate CCT measurement and adjustment without requiring additional sensors or design modifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a color sensor is placed inside the luminaire to directly sample the light, then the CCT measurement can be performed, but the measurement accuracy is degraded due to ambient light interference
Solution Approach 1:
The patent applies periodic action by alternating between two measurement modes: a first measurement mode where the optical sensor measures light from the luminaire, and a second measurement mode where the optical sensor measures only ambient light. The controller switches between these modes periodically, allowing the system to separate the luminaire light signal from the ambient light interference by subtracting the ambient measurement from the total measurement, thereby improving CCT measurement accuracy despite the presence of harmful ambient light factors.
2Measurement precision
If additional sensors are added to distinguish between LED light and ambient light, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
The patent applies universality by enabling a single optical sensor to perform multiple measurement functions through temporal separation. The same optical sensor used to measure luminaire light in the first measurement mode is also used to measure ambient light in the second measurement mode. The controller orchestrates this multi-functionality by switching between measurement modes based on the state of the light emitting devices, eliminating the need for additional sensors while maintaining accurate color point positioning capability.
3Ease of operation
If the optical sensor measures both LED light and ambient light simultaneously, then the measurement process is simple, but the CCT value calculation becomes incorrect
Solution Approach 1:
The patent applies preliminary action by performing a preliminary measurement of ambient light in the second measurement mode before or during the measurement of luminaire light in the first measurement mode. The controller is designed to execute this preliminary ambient light measurement as part of the overall measurement process, allowing the system to later subtract this pre-obtained ambient light value from the total light measurement to calculate the accurate luminaire light contribution and corresponding CCT value.
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 allows for precise CCT measurement and adjustment, improving the accuracy of color point positioning and CCT value calculations by distinguishing between light emitted by LEDs and ambient light, reducing the need for additional sensors and enhancing design flexibility in luminous panels.
Implementation Method 1
an optical sensor (DET) ... designed to provide a sensor signal indicative of incident light
Data Source
AI summary
An optical sensor circuit comprises an optical sensor (DET) designed to provide a sensor signal indicative of a color of light incident on the optical sensor (DET), a clock designed to provide a clocked control signal comprising consecutive high and low states, and a controller unit (CU) connected to the optical sensor (DET) and comprising the clock. The controller unit (CU) is designed to process the sensor signal as a color signal (CTS) in a first mode if the clocked control signal is in a high state, wherein the color signal (CTS) is indicative of a color of light emitted by a light emitting device (LED) to be connected at a control terminal (OUT). The controller unit (CU is further designed to process the sensor signal as an ambient color light signal (aCTS) in a second mode if the clocked control signal is in a low state, wherein the ambient color light signal (aCTS) is indicative of a color of ambient light. The controller unit (CU) is also designed to generate a driving signal (PWM) to drive the light emitting device (LED), wherein the driving signal (PWM) depends on the color and ambient color light signals (CTS, aCTS).