Integrated Dot Projector with Automatic Power Control
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Solution Overview
Problem
Conventional dot projectors with laser diodes have a complex structure and large volume, making them unsuitable for surface mount technology and automatic manufacturing processes, and they require automatic power control to stabilize laser light emission which is affected by driving currents and temperature.
Innovation Solution
A dot projector with an automatic power control integrated circuit (IC) that includes a photodiode, laser diode, reflector, and diffractive optical element, where the photodiode detects stray light to adjust laser power and control light spots, incorporating a feedback mechanism for temperature compensation and protection circuits to ensure stable output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional laser diode modules with heat sinks and separate APC circuits are used, then automatic power control is achieved, but the device volume becomes huge and cannot be applied to surface mount technology
Solution Approach 1:
The patent integrates the APC circuit, photodiode, and laser diode into a single integrated device. The APC circuit and photodiode are formed on the same substrate as the laser diode, eliminating the need for separate heat sinks and external APC circuits. This merging of components directly reduces device volume while maintaining automatic power control functionality.
Solution Approach 2:
The substrate serves multiple functions: it acts as the mounting platform for the laser diode, the APC circuit board, and the photodiode array. The integrated structure combines functions of heat dissipation, optical detection, and power control into a single universal component that is compatible with surface mount technology.
2Illumination intensity
If conventional optical pattern projectors with separate radiation source assemblies are used, then laser beam projection is achieved, but the assembly structure becomes complicated and cannot be applied to automatic manufacturing processes
Solution Approach 1:
The patent combines the radiation source assembly with the APC circuit and photodiode array into a single integrated device. The laser diode, collimator, and DOE are formed on the same substrate, eliminating separate radiation source assemblies and simplifying the overall structure for automatic manufacturing.
Solution Approach 2:
The patent replaces mechanical assembly of separate components with a planar integrated structure formed on a substrate. This substitution of mechanical assembly with integrated circuit fabrication techniques enables automatic manufacturing processes while maintaining laser beam projection functionality.
3Power
If driving currents are increased to improve luminous intensity, then laser output power increases, but temperature rises causing optical attenuation
Solution Approach 1:
The patent implements a feedback mechanism where the photodiode array detects the actual laser output and feeds this information to the APC circuit. The APC circuit adjusts the driving current in real-time to maintain stable output power, compensating for temperature-induced optical attenuation without requiring excessive driving currents.
Solution Approach 2:
The integrated APC circuit continuously monitors and self-adjusts the laser diode operating conditions to maintain stable output. The system serves itself by automatically compensating for temperature effects and optimizing driving current, eliminating the need for external control systems.
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 enables a compact, cost-effective, and stable dot projector with automatic power control, suitable for surface mount technology, achieving efficient light spot control and temperature stabilization, facilitating easier assembly and reduced prime costs.
Implementation Method 1
the photodiode detects a stray light N2 reflected from a housing 36 to generate a feedback signal
Implementation Method 2
a diffractive optical element (DOE) 38 for the diffractive optical element to be above所述 collimator; whereby the laser diode emits a laser light L2 to the reflector 35 and the laser light L2 is reflected perpendicularly through the collimator 37 to the diffractive optical element 38; the diffractive optical element 38 thereby producing a plurality of light spots C
Data Source
AI summary
A dot projector with automatic power control includes a housing covering a substrate with an installing space and a platform therein, an automatic power control integrated circuit, a photodiode and a reflector disposed under the platform of the housing, a collimator disposed in the installing space of the housing and a diffractive optical element bonded on the platform of the housing. Whereby a laser diode emits a laser light to the reflector for the laser light to be reflected perpendicularly through the collimator to the diffractive optical element; then the diffractive optical element produces a plurality of light spots and the a stray light is also produced from the laser light. The photodiode of the automatic power control integrated circuit then detects the stray light and produces a feedback signal transmitted back to the laser diode for adjustment of the laser emission power in order to control the light spots produced by the diffractive optical element.