Diffuser Failure Detection in Imaging Light Modules
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Solution Overview
Problem
Existing imaging devices face risks of diffuser failure due to thermal damage, which can lead to eye safety issues and bulkiness, and current solutions are inadequate in preventing such damage while maintaining compactness.
Innovation Solution
An illumination device with a control module that detects diffuser failure by measuring the angular spread of the light beam, using a waveguide and photoreceptor to ensure reliable detection, and includes a control circuit to deactivate the light source when failure is detected, eliminating the need for separate waveguides and protective glass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If infrared light sources with high intensity are used to maintain sufficient brightness downstream of the diffuser, then the luminous intensity is improved, but the risk to human eye safety increases
Solution Approach 1:
The patent implements a feedback mechanism using a photodetector that continuously monitors the light beam downstream of the diffuser. When the diffuser is intact, it scatters the infrared light and the photodetector detects a specific intensity level. When the diffuser fails (absent or broken), the light beam remains concentrated and the photodetector detects a different intensity pattern. This feedback allows the system to detect diffuser failure and trigger an alarm or shut down the light source, resolving the contradiction by enabling safe high-intensity operation with automatic safety monitoring.
2Object-affected harmful factors
If a diffuser presence detector and light source cutoff mechanism are used to prevent eye damage, then eye safety is improved, but the device complexity increases
Solution Approach 1:
The patent combines the diffuser presence detection function with the existing light emission system by placing a photodetector in the optical path downstream of the diffuser. The same optical components (light source, diffuser, optical output) serve dual purposes: generating illumination and enabling safety monitoring. This merging approach avoids adding separate complex detection systems while achieving eye safety through the integrated photodetector monitoring of the light beam characteristics.
3Reliability
If secure fixing and protective housing are used to prevent diffuser damage, then reliability is improved, but the device complexity and size increase
Solution Approach 1:
The patent implements a self-monitoring system where the photodetector continuously checks the integrity of the diffuser by analyzing the light beam it produces. The system serves itself by using its own operational output (the light beam) as the test signal for detecting failures. This self-service approach eliminates the need for separate protective structures or complex monitoring systems, as the operational parameters themselves provide the failure detection capability.
4Reliability
If conventional diffuser protection methods are used, then diffuser integrity is improved, but compactness is worsened
Solution Approach 1:
The patent introduces a photodetector as an intermediary element that monitors the light beam downstream of the diffuser. This intermediary provides failure detection capability without requiring bulky protective structures. The photodetector acts as a mediator between the light source and the external environment, enabling compact integration of safety monitoring functions within the existing optical path without adding significant volume to the device.
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 provides a compact and safe illumination device that reliably detects diffuser failure, preventing eye hazards and reducing bulkiness, while being suitable for time-of-flight measurement techniques.
Implementation Method 1
an optical diffuser, the light source being configured to generate said light beam, the optical diffuser being arranged to receive the light beam and to diffuse it towards the optical output
Implementation Method 2
the control module comprising a photoreceptor optically coupled to the optical output and configured to measure a light intensity
Implementation Method 3
the control module includes a waveguide which has a propagation direction transverse to the beam and which is configured to optically couple the optical output and the photoreceptor
Data Source
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AI summary
The invention relates to a lighting device comprising a lighting module (2) including an optical output (22) configured to emit a light beam (5) having an angular spread, said module (2) comprising a light source (20) configured to generate the light beam and an optical diffuser (21) arranged to receive and diffuse the beam towards the optical output (22), such that the downstream value (θ2) of the angular spread downstream of the diffuser is greater than the upstream value (θ1) of the angular spread upstream of the diffuser. A control module (3) is configured to emit a control signal (CTRL) having an alarm value when the value of the angular spread of the light beam emitted by the optical output (22) passes below a first threshold, the control module (3) comprising a photoreceptor (30) optically coupled to the optical output (22) and configured to measure a light intensity, wherein the control module (3) is configured to output the control signal (CTRL) having the alarm value when the value of the light intensity falls below a second threshold, the device (1) further comprising a control circuit (4) configured to deactivate the light source (20) upon reception of the control signal (CTRL) having the alarm value. The invention also relates to an imaging system comprising such a device.