Optical Encoder Device Axial Code Wheel Assembly
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Solution Overview
Problem
Conventional optical encoder devices for small-sized motors require a cutout on the printed circuit board, leading to increased size and cost due to the need for an elastic code wheel and complex assembly processes.
Innovation Solution
An optical encoder device where the code wheel is attached axially to the motor shaft without a cutout on the circuit board, using separate light-emitting and light-receiving element modules that are positioned and fixed using a module holder, allowing for a rigid, inexpensive code wheel and reduced board size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cutout is provided on the printed circuit board to accommodate the code wheel, then the code wheel can be positioned without damaging it during assembly, but the board size must be increased and the degree of integration of patterns cannot be increased
Solution Approach 1:
The board unit is divided into two separate modules: a light-receiving element module and a light-emitting element module. This segmentation allows each module to be independently positioned and fixed on the board without requiring a large cutout, thereby maintaining code wheel positioning accuracy while reducing board size.
Solution Approach 2:
The light-emitting and light-receiving elements are positioned in separate planes/dimensions relative to the code wheel. The light-emitting element is disposed at a first position and the light-receiving element at a second position, allowing optical path arrangement that eliminates the need for a large cutout while maintaining detection accuracy.
2Ease of manufacture
If the code wheel is inserted laterally while being bent into the gap of the photosensor module, then the code wheel can be attached to the motor shaft, but an expensive special elastic film must be used and dimensional restrictions apply
Solution Approach 1:
Instead of inserting the code wheel laterally into the photosensor module gap, the invention inverts the assembly sequence: the light-emitting and light-receiving elements are first fixed to the board unit, then the code wheel is attached axially to the motor shaft. This eliminates the need for lateral insertion and bending, allowing use of inexpensive rigid materials.
Solution Approach 2:
The invention replaces the mechanical lateral insertion method with axial attachment. The code wheel is attached to the motor shaft in the axial direction, and the photosensor module is subsequently positioned relative to it, eliminating the need for elastic deformation and special elastic films.
3Adaptability or versatility
If the code wheel and hub are formed as separate members and joined by double-sided tape, then the code wheel can be attached to the motor shaft, but the assembly complexity and cost increase
Solution Approach 1:
The code wheel and hub are merged into a single integrally formed piece. This eliminates the need for separate components and the double-sided tape joining process, reducing assembly complexity while maintaining the flexibility to attach the integrated code wheel-hub assembly to the motor shaft.
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 design enables miniaturization of the encoder device, reduces production costs, and simplifies assembly by eliminating the need for a cutout and using a separate hub for the code wheel, while maintaining accurate rotational detection.
Implementation Method 1
a light-emitting element module accommodating a light-emitting element
Implementation Method 2
a light-receiving element module accommodating a light-receiving element
Implementation Method 3
an optical modulation track portion in which a plurality of slits are provided at uniform intervals in the circumferential direction
Data Source
AI summary
A photosensor module is composed of a light-receiving element module accommodating a light-receiving element, and a light-emitting element module accommodating a light-emitting element, which modules are separate, paired components. One of the paired light-receiving element module and light-emitting element module is mounted on a printed circuit board of a board unit, which is fixed to an end surface of a motor. After a code wheel is attached and fixed to the motor shaft along the axial direction of the motor shaft, a generally L-shaped module holder, which accommodates the other of the paired light-receiving element module and light-emitting element module, is mounted to the board unit. Thus, the light-emitting element and the light-receiving element are positioned such that these elements face each other via the optical modulation track portion of the code wheel.