Optical Encoder Layout for Accurate Absolute Angle Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional optical encoders experience reduced detection accuracy of absolute angles due to displacement in the arrangement of optical system components, leading to misalignment of light irradiation on the scale, which affects the precision of angle measurement.
Innovation Solution
An optical encoder design featuring a rotating member with a light source and photodetecting elements arranged annularly on a scale, where specific areas are designated as bright or dark portions to produce distinct light intensity peaks, allowing for accurate angle calculation even with light misalignment, using a rotating member with a straight-line light transmitting or reflecting portion and photodetecting elements arranged in a zigzag pattern to enhance resolution and detection range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the absolute angle is directly detected from the position of each specified lattice window, then the detection process is simple, but the detection accuracy is lowered when the irradiated position is displaced from reference
Solution Approach 1:
The patent introduces a mediator (the relative angle between light intensity peaks) to indirectly determine the absolute angle. Instead of directly detecting the absolute angle from lattice window positions, the system first measures the relative angle between peaks, then uses this as a reference to calculate the corrected absolute angle, thereby compensating for positional displacements
Solution Approach 2:
The system implements feedback by using the measured relative angle between light intensity peaks to correct the absolute angle detection. The relative angle serves as a feedback signal that indicates the displacement amount, which is then used to adjust and correct the absolute angle measurement to maintain high accuracy
2Ease of manufacture
If the irradiated position of light is displaced from the reference due to processing difficulties or age-based deterioration, then the system remains simple, but the detection accuracy is lowered
Solution Approach 1:
The patent performs preliminary action by establishing the relative angle between light intensity peaks as a reference value before absolute angle detection. This pre-established reference serves as a baseline that can be used to detect and correct any subsequent displacements, allowing the system to maintain accuracy without requiring complex real-time adjustments
Solution Approach 2:
The system changes the detection parameter from directly measuring absolute position to measuring the relative angle between light intensity peaks. This parameter change allows the system to detect displacements as changes in the relative angle, which can then be used to correct the absolute angle measurement and maintain accuracy despite positional drift
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 proposed solution enables high-accuracy detection of absolute angles by correcting for light misalignment, improving the encoder's precision and extending its angle detection range while maintaining a compact scale and reducing costs.
Implementation Method 1
a photodetecting device including a scale having a plurality of photodetecting elements arranged thereon, and an output portion for outputting an output signal based on the light intensity of the light to be detected made incident to the photodetecting elements through the rotating member
Data Source
AI summary
An encoder is provided in which the absolute angle can be detected with high accuracy even when the irradiated position of light to be detected with respect to a scale is displaced from a reference, and a photodetecting device for an encoder used for such an encoder. In the encoder 1, by passing light to be detected through a straight-line light transmitting portion 17, a bright portion 19 to which the light to be detected is irradiated is formed in an area of a scale plate 11 containing mutually separate parts of arranged lines L1 and L2 and also a dark portion 20 to which no light to be detected is irradiated is formed in the other area.