Optical Encoder Light Source Positioning for Miniaturization
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Solution Overview
Problem
Existing optical encoders face challenges in obtaining sufficient light without increasing power consumption and size, with previous designs either using inefficient light reception or requiring large configurations.
Innovation Solution
An optical encoder with a scale and readhead where the light source is positioned between the scale-side lens and light receiving element, with the optical axis of the light source matched to the scale-side lens, allowing for efficient light transmission and reception without a half-mirror, enabling miniaturization and improved focal depth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a half-mirror is used to separate optical paths in a reflection type optical reader, then the optical path of emitted light and reflected light can be separated, but the light receiving unit cannot obtain a sufficient amount of light
Solution Approach 1:
The patent removes the half-mirror component from the optical system and extracts only the essential function of optical path separation. Instead of using a half-mirror to split and combine light paths, the invention uses a direct linear arrangement where the light source, scale, and light receiving element are positioned on the same optical axis, eliminating the need for beam splitting and combining components.
Solution Approach 2:
The optical system is segmented into distinct functional components (light source, scale, light receiving element) arranged in a linear sequence. This segmentation allows each component to perform its function independently without the need for complex light path manipulation, improving light transmission efficiency.
2Illumination intensity
If the amount of light emitted from the light-emitting diode is increased to obtain sufficient light, then light reception is improved, but power consumption increases and lifetime decreases
Solution Approach 1:
The patent replaces the mechanical/optical system involving half-mirrors and complex light path management with a simpler geometric arrangement. By optimizing the spatial positioning of components and using a scale with high reflectivity characteristics, the system achieves efficient light reception without increasing light source intensity, thereby reducing power consumption.
Solution Approach 2:
The invention changes key parameters of the optical system including the distance between components, the angle of light incidence, and the reflectivity characteristics of the scale. These parameter optimizations enable sufficient light reception with lower light source intensity, reducing power consumption and extending light source lifetime.
3Illumination intensity
If the scale and light receiving element are arranged in parallel to achieve sufficient light, then light reception is improved, but the encoder becomes large in size
Solution Approach 1:
The patent transitions from a parallel arrangement (two-dimensional separation) to a linear collinear arrangement (one-dimensional alignment). By positioning the light source, scale, and light receiving element on the same optical axis in sequence, the system achieves compact miniaturization while maintaining efficient light reception through optimized optical geometry.
4Ease of operation
If four lenses are arranged between the scale and light receiving element to achieve parallel arrangement, then the scale and light receiving element can be arranged in parallel, but the encoder becomes large in size
Solution Approach 1:
The patent removes the complex multi-lens system from the optical path and extracts only the essential light transmission function. By using a simplified optical arrangement with fewer components, the invention achieves the desired parallel arrangement capability without the size penalty of multiple lenses.
Solution Approach 2:
The functions of multiple lenses are merged into a simplified optical configuration. The patent combines light transmission, focusing, and alignment functions into a more compact arrangement, reducing the overall encoder size while maintaining the ability to achieve proper optical alignment between scale and light receiving element.
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 allows for sufficient light reception, miniaturization of the encoder, and increased focal depth, reducing power consumption and size while maintaining accurate measurement capabilities.
Implementation Method 1
a scale-side lens that transmits the light emitted from the light source to the scale and transmits the light reflected by the scale to the light receiving element
Implementation Method 2
receives the light reflected by the scale
Implementation Method 3
a distance between the light source and the scale-side lens is set to be a focal distance of the scale-side lens
Data Source
Figure 1
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AI summary
A miniaturized optical encoder capable of obtaining a sufficient amount of light in the light receiving element is provided. An optical encoder 1 includes a scale 2 having scale markings 21 and a readhead 3 having a light source 31 that emits light to the scale 2, a scale-side lens 32 that transmits the light emitted from the light source 31 to the scale 2, and a light receiving element 33 that receives the light that has been reflected by the scale 2 and that has passed through the scale-side lens 32. The light source 31 is arranged between the scale-side lens 32 and the light receiving element 33, and a distance between the light source 31 and the scale-side lens 32 is set to be a focal distance fs of the scale-side lens 32. An optical axis Lsrc of the light source 31 is matched with an optical axis Ls of the scale-side lens 32 in a reading direction of the scale markings 21 and is separated from an optical axis Ls of the scale-side lens 32 by a predetermined distance D in a direction perpendicular to the reading direction of the scale markings 21.