Single Photodiode Timing Control for Laser Scanner Alignment
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Solution Overview
Problem
Existing image projection apparatuses require multiple photodiodes to correct shifts between forward and backward images, leading to increased volume and complexity in the optical engine.
Innovation Solution
A control device and method that utilize a single photodiode to correct shifts between forward and backward images by adjusting the reference timing and correction time based on environmental changes, such as temperature and light intensity, allowing for precise alignment without the need for multiple photodiodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple photodiodes are installed to correct shifts between forward and backward images, then image alignment accuracy is improved, but device complexity and volume increase
Solution Approach 1:
A single photodiode is designed to perform multiple functions: detecting both forward path light and backward path light, and providing timing information for both image alignment corrections. The photodiode is positioned to receive light from both scanning directions, eliminating the need for separate photodiodes for each path while maintaining alignment accuracy.
Solution Approach 2:
The patent merges the functions of multiple photodiodes into a single photodiode by combining the light detection paths. The single photodiode receives and processes light signals from both forward and backward scanning paths, consolidating what would traditionally require separate detection elements and reducing overall system complexity.
2Measurement precision
If multiple photodiodes are installed to correct shifts between forward and backward images, then image alignment accuracy is improved, but the volume of the optical engine part increases
Solution Approach 1:
The single photodiode is configured to detect light from both forward and backward scanning paths, performing the work of multiple photodiodes in a compact form factor. This multi-functional approach maintains alignment correction capability while minimizing the volume occupied by detection components.
Solution Approach 2:
By merging multiple light detection functions into a single photodiode component, the optical engine volume is reduced. The consolidated design eliminates the need for multiple separate photodiode assemblies and their associated mounting structures, thereby decreasing the overall optical engine footprint.
3Stability of the object's composition
If reference timing and light emission timing are adjusted based on environmental changes, then image alignment stability is improved, but control system complexity increases
Solution Approach 1:
The system uses feedback from the single photodiode to detect timing variations caused by environmental changes. The photodiode's light reception timing serves as feedback information that is used to adjust reference timing and light emission timing, creating a closed-loop control system that maintains alignment stability despite environmental variations.
Solution Approach 2:
The control system dynamically adjusts timing parameters (reference timing and light emission timing) based on detected environmental changes. By modifying these temporal parameters in response to environmental conditions, the system maintains image alignment stability without requiring complex mechanical or structural changes.
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 effectively suppresses shifts between forward and backward images using a single photodiode, reducing the size and complexity of the image projection apparatus while maintaining image alignment accuracy.
Implementation Method 1
a photodiode (PD) installed around an image drawing area and controlling a mirror rotation angle and a light emission timing on the basis of a light receiving timing of the PD
Implementation Method 2
a piezoelectric type light deflection mirror in which a thin piezoelectric material is superimposed on a beam-shaped elastic member of the mirror for driving to form a piezoelectric actuator
Data Source
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AI summary
A control device (10) includes an acquirer (32), a timing detector (33), a controller (30), and a driver (31). The acquirer (32) is configured to acquire an output voltage from a light detector (16) for receiving laser light scanned by a light source (12) and a deflector (13). The timing detector (33) is configured to detect reference timings of the laser light on forward and backward paths in a scanning direction based on the output voltage. The controller (30) is configured to generate a control signal for causing the light source (12) and the deflector (13) to draw a forward path image on a scanned surface from time obtained by adding a time to the reference timing on the forward path and to draw a backward path image on the surface from time obtained by adding a time to the reference timing on the backward path. The driver (31) is configured to draw the images by driving the deflector (13), based on the control signal.