Laser Projection Device Thermoinduction Sensor Signal Change Rate Control
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Solution Overview
Problem
Existing laser projection systems face inaccuracies in determining whether a human body is within the induction range of a thermoinduction sensor, leading to erroneous activation of protective measures, as the sensor's output signal can be triggered by heat flow from the device itself or a human body, causing unnecessary reduction in laser luminance.
Innovation Solution
A method and apparatus that utilize a thermoinduction sensor to acquire infrared signals and calculate signal change rates, comparing these rates to preset values to accurately determine if a human body is present, thereby adjusting the operation mode of the laser projection device between human eye protection and viewing modes based on the signal change rates and threshold values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the laser projection device operates at high luminance to provide good viewing quality, then the viewing experience is improved, but the risk of eye damage increases when a human body is within the induction range
Solution Approach 1:
The laser projection device dynamically adjusts its luminance based on the detected signal change rate. When a human body is detected (high signal change rate), the luminance is reduced to a safe level. When no human body is present (low signal change rate), the luminance is maintained at high level for optimal viewing quality. This dynamic adjustment resolves the contradiction between viewing quality and eye safety.
2Object-affected harmful factors
If the thermoinduction sensor activates the human eye protection mode based on signal threshold, then eye safety is improved, but the laser luminance is unnecessarily reduced when the signal is caused by device heat flow rather than a human body
Solution Approach 1:
The patent changes the detection parameter from absolute signal threshold to signal change rate threshold. By detecting the rate of change of the sensor output signal rather than just the absolute value, the system can distinguish between human body detection (rapid signal change) and device heat flow (slow signal change). This parameter change eliminates false activation of the protection mode while maintaining eye safety when truly needed.
3Object-affected harmful factors
If the laser projection device frequently switches between viewing mode and human eye protection mode, then eye safety is ensured, but the viewing experience is degraded due to unnecessary luminance reduction
Solution Approach 1:
The system continuously monitors the thermoinduction sensor output signal and its change rate, providing real-time feedback to the control unit. This feedback mechanism allows the system to make accurate, data-driven decisions about when to switch modes, avoiding unnecessary switches and maintaining stable high luminance during normal operation while ensuring safety when needed.
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 approach enhances the accuracy of controlling laser projection devices by preventing erroneous activation of the human eye protection mode, ensuring appropriate luminance levels are maintained based on the presence or absence of a human body within the sensor's range, thus reducing unnecessary luminance reduction.
Implementation Method 1
a thermoinduction sensor on a housing of the laser projection device for acquiring an infrared signal in an environment where the laser projection device is located
Data Source
AI summary
The application provides a method and an apparatus for controlling a laser projection device, the laser projection device being provided with a thermoinduction sensor on housing for acquiring an infrared signal in environment where the laser projection device is located, the method including: acquiring first signal outputted by the thermoinduction sensor in first moment and second signal outputted in current moment, the first moment being prior to the current moment, first signal and second signal being signals outputted by the thermoinduction sensor according to the infrared signal; determining a first signal change rate according to first difference between first signal and second signal and second difference between first moment and current moment; reading a preset signal change rate and a threshold signal; determining an operation mode of laser projection device according to magnitude relation of first signal change rate and preset signal change rate, second signal and threshold signal.