Optical Encoder Curved Reflection Structures
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Solution Overview
Problem
Existing optical rotary encoders face challenges in achieving high position resolution and sensitivity without being finely divided, as reducing the size of light reflectors and non-light reflectors leads to decreased detection sensitivity and requires advanced manufacturing techniques for accurate formation.
Innovation Solution
The encoder features a rotary plate with reflection structures having convex or concave surfaces, each with a width that is an integral multiple of the light reflector or transmissive part, allowing for high position resolution and sensitive rotation angle detection without fine division, using a combination of reflection structures and a code pattern to enhance detection sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the light reflector and non-light reflector are finely divided to achieve high position resolution, then the position resolution is improved, but the amount of reflected light is halved causing detection sensitivity to deteriorate
Solution Approach 1:
The patent applies curvature by forming the light reflector surface as a spherical or aspherical surface instead of a flat surface. This curved surface focuses the reflected light onto a specific point on the photodetector array, concentrating the light energy and maintaining high detection sensitivity even when the reflector size is reduced for fine division. The curvature allows the system to achieve high position resolution without sacrificing the amount of reflected light.
Solution Approach 2:
The patent introduces a new dimension by using a three-dimensional spherical or aspherical surface instead of a two-dimensional flat surface. This adds a vertical dimension to the light reflection geometry, enabling the light to be focused from a broader area onto the photodetector. This dimensional change allows the system to maintain adequate light collection while reducing the lateral size of the reflector for finer division.
2Measurement precision
If the light reflector is formed finely to achieve high position resolution, then the position resolution is improved, but advanced manufacturing techniques are required to accurately form the light reflector
Solution Approach 1:
The patent changes the geometric parameters by using a spherical or aspherical surface with specific curvature radii that can be achieved through conventional manufacturing techniques. By selecting appropriate curvature parameters, the design maintains manufacturability while achieving the necessary light focusing capability for high position resolution. The spherical or aspherical geometry provides a clear design criterion that simplifies the manufacturing process compared to achieving the same effect with flat surfaces requiring ultra-precise positioning.
3Measurement precision
If the size of light reflector and non-light reflector is halved to achieve high position resolution, then the position resolution is improved, but the amount of reflected light received by light receiving element is halved
Solution Approach 1:
The spherical or aspherical surface acts as a light-focusing element that concentrates reflected light onto a specific region of the photodetector. This geometric curvature enables the system to maintain adequate light collection efficiency even when the reflector area is reduced, as the curved surface redirects light from a broader angular range onto the photodetector's active area, compensating for the reduced reflector size.
Solution Approach 2:
The patent utilizes the focusing effect of the spherical or aspherical surface to concentrate light energy, similar to how a lens focuses light. The curved geometry creates a focal point where light rays converge, effectively concentrating the reflected light energy onto the photodetector and maintaining high signal strength despite the reduced reflector area.
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 configuration enables high position resolution and sensitive detection of rotation angles, improving detection sensitivity and accuracy while avoiding the need for advanced manufacturing techniques and fine division of light reflectors, thereby enhancing the encoder's performance.
Implementation Method 1
Each of the plurality of reflection structures has a surface in a convex or concave shape... The plurality of reflection structures each have a width that is an integral multiple of a width of the light reflector or the light transmissive part
Data Source
AI summary
Provided is an encoder capable of achieving high position resolution without being finely divided, and capable of detecting a rotation angle or the like with high sensitivity. The encoder includes: rotary plate having a plurality of reflection structures repeatedly formed and code including light reflector; irradiator that irradiates the plurality of reflection structures with light; and light receiver that receives light reflected by the plurality of reflection structures. Each of the plurality of reflection structures has a surface in a convex shape, and each of the plurality of reflection structures has a width that is an integral multiple of a width of light reflector.