Encoder Scale Inclined Surface for Detection Accuracy
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Solution Overview
Problem
Existing optical encoders face challenges in improving detection accuracy due to the limitations of glass substrates, which are costly and inflexible, leading to reduced light detection precision.
Innovation Solution
An encoder scale with a tabular base material, featuring a resin layer and metal film on one surface, and a second surface inclined relative to the first, allowing for differentiated light reflection directions, enabling the use of less expensive and more machinable materials like single crystal silicon, thereby enhancing detection accuracy and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If glass substrate is used as base material, then detection accuracy is maintained, but cost increases and flexibility decreases
Solution Approach 1:
The patent changes the surface orientation parameter of the base material from horizontal (parallel to light incidence) to inclined (at a specific angle). This parameter change enables the use of inexpensive crystal materials like silicon while maintaining high detection accuracy by directing reflected light away from the photodetector through the inclined surface geometry.
2Ease of manufacture
If surface extends along same direction as metal film, then manufacturing is simplified, but light beam reflection interferes with detection accuracy
Solution Approach 1:
The patent introduces asymmetry by inclining the surface at a specific angle relative to the metal film orientation. This asymmetric configuration causes reflected light to deviate from the photodetector path, eliminating interference while maintaining manufacturing feasibility through standardized processing techniques.
3Use of energy by moving object
If transparent base material is used, then light transmission is achieved, but material selection is limited and cost increases
Solution Approach 1:
Instead of relying on light transmission through transparent materials, the patent inverts the approach by using opaque or non-transparent crystal materials and controlling light reflection through inclined surface geometry. This inversion expands material selection to include cost-effective crystal materials while achieving the necessary optical functionality.
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 improves detection accuracy while reducing costs by utilizing anisotropically etchable crystal materials like single crystal silicon, allowing for precise formation of the encoder scale suitable for both linear and rotary encoders, and achieving high light reflectance and machinability.
Implementation Method 1
a resin layer disposed on the base material and including photosensitive resin
Implementation Method 2
a metal film disposed on the resin layer... increase light reflectance of the first region
Implementation Method 3
A surface of the second region is configured mainly by a second surface inclined with respect to the first surface... differentiate directions of lights reflected in the first region and the second region
Data Source
AI summary
An encoder scale includes a tabular base material and an optical pattern provided above one surface of the base material, a first region and a second region being disposed side by side above the optical pattern. The first region includes a resin layer disposed above the base material and including photosensitive resin and a metal film disposed above the resin layer and formed of a metal material. The surface of the first region is configured mainly by a first surface having a normal line in the thickness direction of the base material. The surface of the second region is configured mainly by a second surface inclined with respect to the first surface.