Vehicle Headlamp Laser Modulation for Fast Switching
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Solution Overview
Problem
Existing vehicle headlamps with laser light sources often exhibit sluggish behavior in switching on and off due to the need to control large currents, which can lead to safety issues, particularly in emergency shutdowns or masking processes to avoid dazzling other road users.
Innovation Solution
Incorporating an electro-optical modulator, such as a Pockels cell, in the beam path of the laser light source, controlled by a control unit, which affects the polarization of the light and is accompanied by a polarisation element, allowing for precise and efficient modulation of the laser beam, enabling faster switching and sharper mask-out edges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If laser light sources are used to increase luminance and light output, then illumination intensity is improved, but switching response time deteriorates due to sluggish behavior in switching on and off
Solution Approach 1:
An electro-optical modulator is introduced as an intermediary component in the beam path of the laser light source. This modulator, controlled by a control unit, rapidly adjusts the polarization state of the laser beam using voltage control, enabling fast switching and masking operations without directly controlling the laser current, thus resolving the contradiction between maintaining high luminance and achieving fast switching response.
2Power
If large currents are controlled to operate laser light sources, then power output is improved, but switching precision deteriorates due to sluggish switching behavior
Solution Approach 1:
The direct electrical control of laser current is replaced by an electro-optical modulator that uses voltage-controlled polarization adjustment to control the laser beam. This substitution of control mechanism enables precise and rapid switching without the sluggishness associated with direct large current control, thereby improving switching precision while maintaining power output.
Solution Approach 2:
The control approach changes from directly controlling current parameters to controlling voltage parameters that affect polarization state. This parameter change enables more precise and faster control of the laser beam output, improving switching precision while maintaining the required power output for illumination.
3Illumination intensity
If laser beam is directly emitted to maximize light output, then illumination intensity is improved, but safety deteriorates due to endangering humans and other living beings
Solution Approach 1:
A light conversion means containing phosphor is introduced as an intermediary between the laser light source and the external environment. This converter transforms the high-intensity laser beam into diffuse white light, maintaining illumination intensity while eliminating the hazardous concentrated laser beam, thus resolving the safety concern.
Solution Approach 2:
The potentially harmful concentrated laser beam is converted into beneficial diffuse white light through the phosphor converter. The high intensity of the laser, which poses a safety risk, is transformed into safe and useful illumination, turning a harmful factor into a benefit for road illumination.
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 enables faster and more precise control of the laser beam, ensuring immediate blocking or dimming of the beam when necessary, thereby enhancing safety by preventing blurred light images and improving the responsiveness of the headlamp's masking and illumination functions.
Implementation Method 1
at least one electro-optical modulator (4) is arranged in the beam path of the at least one laser light source (1), which at least one electro-optical modulator (4) is controlled by a control unit (12) and lies before the light conversion means (8) in the beam path and affects the polarisation of the light
Implementation Method 2
wherein a polarisation element is arranged at least after the modulator in the beam path
Implementation Method 3
The laser beam is rather directed towards an interposed converter, which contains a luminescence conversion material, or 'phosphor' for short, and is converted by this light conversion means from, for example, blue light into preferably 'white' light
Data Source
AI summary
A headlamp for vehicles, in which the laser beam of at least one laser light source (1) is directed via a beam deflection means (7) towards at least one light conversion means (8) in a scanning manner, which at least one light conversion means comprises a phosphor for converting light, and having a projection system (10) for projecting the light image (9) generated at the light conversion means onto the roadway (11), characterized in that at least one electro-optical modulator (4) is arranged in the beam path of the at least one laser light source (1), which at least one electro-optical modulator is controlled by a control unit (12) and lies before the light conversion means (8) in the beam path and affects the polarization of the light, wherein a polarization element (3, 5, 17) is arranged at least after the modulator in the beam path.