Optical Encoder Protector Inclination Diverts Reflected Light
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Solution Overview
Problem
The accuracy of photoreception signals in optical encoders is compromised when using a scale with a protective member made of light-transmissive material, as the reflected light from the protective member can interfere with the detection process.
Innovation Solution
An optical encoder design featuring a scale with bar-like marks, a detection head with a light source fiber and photoreceiver fibers positioned perpendicularly, and a protector with a top surface inclined relative to the scale to divert reflected light away from the photoreceiver fibers, maintaining signal accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective member made of light-transmissive material is placed over the scale, then the scale is protected from dust and scratches, but reflected light from the protective member interferes with the photoreception signal accuracy
Solution Approach 1:
The top surface of the protective member is designed with an inclination angle relative to the principal surface of the scale, creating an asymmetric structure. This asymmetry causes reflected light to diverge at specific angles that do not enter the photoreceiver fiber, thereby eliminating interference while maintaining protection functionality
Solution Approach 2:
The solution transitions from a two-dimensional flat protective surface to a three-dimensional inclined surface. By introducing the inclination angle dimension, the protective member redirects reflected light away from the detection path while still covering the scale marks, resolving the contradiction between protection and measurement accuracy
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 effectively inhibits the influence of reflected light from the protective member, ensuring high accuracy of the photoreception signal and preventing interference, thus maintaining signal integrity.
Implementation Method 1
a detection head having a light source fiber emitting (i.e., firing) coherent light at the scale and a photoreceiver fiber receiving light reflected off the scale
Implementation Method 2
the top surface of the protector is inclined with respect to the scale so as to divert the light reflected off the top surface of the protector away from the photoreceiver fiber of the detection head
Data Source
Figure 1
Figure 2A~2B
Figure 3~4
AI summary
An optical encoder includes a scale having bar-like scale marks; a detection head having a light source fiber emitting coherent light at the scale and a photoreceiver fiber receiving light reflected off the scale; electronic components connected to the detection head via the light source fiber and the photoreceiver fiber; and a protector covering the scale marks at a predetermined distance from the scale marks. The protector is a member configured with light-transmissive material and includes a top surface that is inclined with respect to a principal surface of the scale.