Optical Encoder Single PCB Integration
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Solution Overview
Problem
Optical encoders are complex and fragile due to the requirement of two printed circuits, precise wiring, and micromechanics, making them industrially difficult to produce and assemble effectively.
Innovation Solution
Integrating light-emitting diodes and photoelectric cells on the same printed circuit, with a reflective element and masks to control light transmission, allowing for direct or reflective optical transmission between emitters and detectors, reducing the need for precise positioning and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If light-emitting diodes and photoelectric cells are mounted on separate printed circuits with precise wiring, then measurement precision is maintained, but device complexity increases and ease of manufacture decreases
Solution Approach 1:
The patent merges the light-emitting diodes and photoelectric cells onto a single printed circuit board, eliminating the need for separate circuits and complex inter-circuit wiring. This integration maintains measurement precision through the use of a reflective element that creates a defined optical path, while simultaneously reducing device complexity by consolidating components.
Solution Approach 2:
The patent introduces a reflective element as an intermediary between the light source and detector. This mediator creates a controlled optical reflection path that ensures precise encoding detection while allowing the emitter and detector to be positioned on the same circuit board, thus resolving the contradiction between precision and complexity.
2Reliability
If two separate printed circuits with wiring are used, then optical encoding function is achieved, but ease of manufacture worsens and reliability decreases
Solution Approach 1:
By combining all optical components (emitter, detector, and reflective element) onto a single printed circuit board, the patent eliminates multiple assembly steps and inter-circuit wiring connections. This single-board integration significantly improves ease of manufacture while enhancing reliability by reducing the number of potential failure points from wiring and alignment issues.
3Measurement precision
If precise relative positioning of components is required, then measurement precision is improved, but device complexity increases and ease of manufacture decreases
Solution Approach 1:
The reflective element serves as a mediator that establishes a precise optical path between the emitter and detector without requiring their direct physical alignment. This allows the system to achieve high angular resolution through the controlled reflection geometry while simplifying the mechanical assembly requirements, as the components can be positioned on the same circuit board with standard tolerances.
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
Simplifies the production process by widening manufacturing tolerances and reducing the risk of optical leaks, resulting in a more robust and reliable optical encoder.
Implementation Method 1
a light source which is a light-emitting diode
Implementation Method 2
at least one reflective element which is an element reflecting the radiation coming from one of the light-emitting diodes in the direction of the corresponding photoelectric cell
Implementation Method 3
a detector which is a photoelectric cell sensitive to the radiation emitted by the light-emitting diodes
Data Source
Figure 1
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Figure 3
AI summary
The invention relates to optical encoders providing binary logic signals representing increments of the relative position of a moving element (10) with respect to a fixed element (11). The encoder comprises a light emitter (14e, 15e) and a light detector (14r, 15r). The emitter and detector are arranged on a planar printed circuit board (13), which is attached to the fixed element (11). To prevent direct radiation between the emitter and the detector, an opaque cover (22), attached to the printed circuit board (13), surrounds the emitter and/or the detector and includes a window (23) that limits the angular field of the light radiation. During the movement of the moving element relative to the fixed element, a marker (20) in the form of a reflective element, attached to the moving element (10), can be positioned in the path of the radiation from the emitter and reflect it towards the detector to be detected there.A mask (25) can interrupt the light radiation by blocking the window (23) when the reflective element (20) does not reflect the radiation emitted by the emitter (14e,15e).