Laser Diode Orientation for Homogeneous Illumination
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Solution Overview
Problem
Existing position measuring devices face limitations in achieving high accuracy due to non-uniform illumination and intensity fluctuations, which affect the quality of the code projection and lead to insufficient resolution in angle measurements.
Innovation Solution
The laser diode is arranged transversely to the sensor array, with its fast axis oriented parallel to the code carrier, allowing for more homogeneous illumination and reducing the negative impact of the intensity profile, enabling higher contrast and accuracy in position measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the laser diode emitter edge is aligned parallel to the sensor array, then the device structure is simple, but the illumination is non-uniform and measurement precision is insufficient
Solution Approach 1:
The patent applies asymmetry by rotating the laser diode emitter edge from a parallel alignment to a transverse alignment relative to the sensor array. This asymmetric arrangement changes the illumination pattern from non-uniform to homogeneous, resolving the contradiction between structural simplicity and measurement precision. The transverse orientation creates a more uniform light distribution across the code carrier while maintaining reasonable device complexity.
2Measurement precision
If the exposure time is increased to improve code projection quality, then measurement precision improves, but productivity decreases
Solution Approach 1:
The patent applies parameter changes by modifying the illumination characteristics through the transverse arrangement of the laser diode. This changes the physical parameter of light distribution from non-uniform to homogeneous, which improves code projection quality and enables shorter exposure times. The improved illumination uniformity allows for reduced exposure times while maintaining measurement precision, thus resolving the contradiction between precision and productivity.
3Ease of manufacture
If the code carrier is illuminated with conventional laser diodes, then the device is inexpensive, but intensity fluctuations reduce measurement precision
Solution Approach 1:
The patent applies dimensionality change by rotating the laser diode emitter edge from a parallel orientation to a transverse orientation relative to the sensor array. This dimensional reorientation transforms the illumination pattern, utilizing the fast axis divergence characteristic to create homogeneous illumination. This approach maintains the use of inexpensive laser diodes while eliminating intensity fluctuations that would otherwise reduce measurement precision.
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 arrangement results in increased measuring accuracy and improved code readability, allowing for shorter exposure times and enhanced resolution in position measurements compared to previous technologies.
Implementation Method 1
a laser diode (20) emits optical radiation by means of its emitter edge (21) onto a code carrier (10)
Implementation Method 2
the code carrier (10) is scanned by a scanning device... a detection element (30)... Depending on the radiation received within the individual detection areas, signals with radiation reception information are generated
Data Source
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AI summary
The invention relates to an optoelectronic measurement method for determining a position, particularly an angle or a length, of a code carrier (10) that carries a position code (11) and is movable relative to a detector element (30) with a degree of freedom, particularly in a rotary or translational fashion. The detector element (30) has at least one line in the longitudinal direction comprising a plurality of light-sensitive receiving regions (31) disposed in a linear fashion. In the course of the positional measurement method, a projection is produced of part of the position code (11) on the detector element (30) that is dependent on the position of the code carrier (10); said projection is produced by at least an emission of optical radiation onto the code carrier (10) using a laser diode (20) having an emitter edge (21), and said projection is detected by the detector element (30). The position of the code carrier (10) relative to the detector element (30) is derived from the projection. According to the invention, in the projection on the detector element (30) thus produced, the axis of divergence of the laser diode emission (26) running perpendicular to the emitter edge (21) has a substantially parallel orientation to the longitudinal axis (34) of the detector element (30).