In-Situ Calibration of Optical Sensors Using Calibrated Light Pulses
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Solution Overview
Problem
Ambient light sensors exhibit significant part-to-part variation due to uncharacterized organic color filters and dark ink variations, leading to ±10% error in lux readings, which existing calibration methods struggle to accurately address, especially in assembly line settings where complexity and time are concerns.
Innovation Solution
An in-situ calibration system comprising a calibration head with a calibrated light source, power source, interface unit, and control unit, which aligns with the optical sensor arrangement to emit a calibration pulse sequence, allowing for autonomous calibration that corrects for system errors and stores calibration data for later use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If in-situ calibration is implemented on the assembly line, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The calibration system is segmented into modular components: a calibration head with light sources, a power source with switching unit, and an interface unit. This segmentation allows each component to be independently optimized and simplified, reducing overall system complexity while maintaining calibration precision.
Solution Approach 2:
The calibration head is designed as a universal device that can calibrate multiple optical sensors on the assembly line. The interface unit provides multi-functional control, enabling the system to serve both calibration purposes and potentially other testing functions, thereby justifying the complexity through versatility.
2Measurement precision
If in-situ calibration is implemented on the assembly line, then measurement precision is improved, but productivity decreases
Solution Approach 1:
The calibration process is designed to perform all necessary measurements and corrections in a single preliminary action during assembly line operation. The calibration head rapidly sequences through multiple light sources and measurements, completing the entire calibration routine in minimal time before the product moves to the next station.
Solution Approach 2:
The calibration system uses periodic action by sequentially activating different light sources in the calibration head at predetermined intervals. This periodic sequencing allows efficient measurement of multiple parameters without requiring continuous operation, optimizing the balance between precision and speed.
3Ease of manufacture
If conventional calibration methods are used, then ease of manufacture is maintained, but measurement precision is insufficient
Solution Approach 1:
The calibration system incorporates self-service features where the interface unit automatically controls the switching unit and calibration head based on pre-programmed sequences. The system performs self-diagnosis and self-adjustment during calibration, reducing the need for manual intervention and expert operation while achieving high precision.
Solution Approach 2:
The calibration system implements feedback mechanisms where the optical sensor measurements are continuously monitored and compared against reference values. The system automatically adjusts calibration parameters based on this feedback, enabling precise calibration without requiring complex manual adjustment procedures.
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 enhances detection accuracy, simplifies the calibration process, and minimizes production time by correcting for aperture misalignment and dark ink variations, achieving better than ±10% accuracy with reduced complexity and time requirements.
Implementation Method 1
The calibration head comprises at least one calibrated light source located behind the aperture
Implementation Method 2
an optical sensor arrangement to be calibrated. For calibration the optical sensor arrangement can be placed with respect to an aperture in the calibration head
Data Source
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AI summary
An assembly line in-situ calibration arrangement, optical sensor arrangement and a method for calibration of an optical sensor arrangement are presented. A calibration arrangement (1) comprises a calibration head (10) comprising at least one calibrated light source (17R, 17G, 17B) located behind an aperture in a housing (11) and being electrically connected to a power terminal. A power source (30) is connected to the power terminal, the power source (30) comprising a switching unit (32R, 32G, 32B, 32C) electrically connected to the at least one light source (17R, 17G, 17B). An interface unit (40) is connected to the switching unit (32R, 32G, 32B, 32C) by means of an interface connection (41), wherein the interface unit (40) is arranged to control the switching unit (32R, 32G, 32B, 32C). A control unit (50) is connected to the interface unit (40), wherein the control unit (50) is arranged to drive the interface unit (40) such that the at least one light source (17R, 17G, 17B) is switched to emit a calibration pulse sequence to be received by the optical sensor arrangement (2) to be placed with respect of the aperture. The calibration pulse sequence is arranged to initiate a calibration mode of operation of the optical sensor arrangement (2).