Laser Projection Current Threshold Control
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Solution Overview
Problem
Existing projection type display apparatuses using semiconductor laser elements face issues with excessive current leading to high-power density light emission due to time delays in cutting off the current supply, resulting in inconvenience and unnecessary light output.
Innovation Solution
A control method and device that detects current thresholds to prevent high-power density light emission by modulating the light output when the current exceeds a first threshold and cutting off the supply when it exceeds a second threshold, using a current detection unit and a controller to manage the driving of the semiconductor laser element and modulation element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a switch is used to cut off the connection between the driving device and the semiconductor laser element when excessive current is detected, then the harmful light emission is prevented, but the circuit remains in open state causing loss of convenience and extended suspended operating state
Solution Approach 1:
The patent applies dynamics by making the switch state changeable based on real-time current detection. The switch transitions from closed to open state dynamically when excessive current is detected, and can return to closed state when current恢复正常, enabling adaptive response to operating conditions rather than fixed state
Solution Approach 2:
The system implements self-service through automatic current monitoring and switch control. The driving device autonomously detects excessive current conditions and activates the switch to cut off the circuit without external intervention, then automatically restores operation when the anomaly is resolved
2Object-affected harmful factors
If a switch is used to cut off the connection between the driving device and the semiconductor laser element, then the current flow is interrupted, but a time delay occurs from control to actual cutoff allowing high-power density light emission
Solution Approach 1:
The patent applies preliminary action by continuously monitoring the current before excessive current conditions fully develop. The system detects current anomalies in advance and activates the switch proactively to prevent high-power density light emission before it occurs, rather than reacting after the problem manifests
Solution Approach 2:
The system implements feedback through continuous current detection and real-time switch control. The driving device monitors current flow and provides feedback to the switch control mechanism, enabling rapid response to current anomalies and minimizing the time delay between detection and cutoff
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 inhibits the output of unnecessary light and reduces the duration of suspended operating states, minimizing convenience loss and preventing high-power density light from being emitted externally.
Implementation Method 1
a laser light source that outputs laser light in accordance with the supply of current
Implementation Method 2
a modulation element that modulates light output from the laser light source and emits the modulated light
Data Source
AI summary
A projection type display apparatus includes: a semiconductor laser element that outputs laser light based on supply of current; a digital mirror device (DMD) that modulates the light output from the semiconductor laser element and emits the modulated light; a projection lens that projects the incident light via the DMD; a drive unit that drives the semiconductor laser element and includes a current detection unit for detecting the current value of the current flowing through the semiconductor laser element; and a controller that, when the current value detected by the current detection unit becomes greater than a first threshold, controls driving of the DMD so that the light output from the DMD will not be incident on the projection lens, and when the current value detected becomes greater than a second threshold greater than the first threshold, causes the drive unit to cut off the supply of current.