Flat-Surface Proximity Sensor With Sealed Light Passages Against Dirt
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Solution Overview
Problem
Miniaturized proximity sensors are prone to dirt accumulation due to simplified protection structures, leading to misjudgment or failure in signal transmission and reception, as they lack effective shielding to prevent environmental interference.
Innovation Solution
A proximity sensor design featuring an enclosed accommodation space with sealed light passages made of light-transmissible materials for both the transmitter and receiver units, along with optional light shielding materials to prevent dirt ingress and minimize stray light interference, ensuring reliable signal detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the protection structure for the sensor is simplified to reduce product size, then the device size is reduced, but dirt can fall inside the product to interfere with sensing capability
Solution Approach 1:
The housing is divided into multiple portions (first housing portion and second housing portion) that define separate enclosed accommodation spaces for the transmitter unit and receiver unit. This segmentation allows each component to be protected independently while maintaining a compact overall structure, resolving the contradiction between miniaturization and protection.
Solution Approach 2:
Light-transmissible windows are introduced as intermediary elements that allow light signals to pass through while preventing dirt ingress. These windows act as mediators between the internal sensor components and the external environment, enabling sensing functionality while maintaining protection against contaminants.
2Reliability
If openings are provided for light signal transmission, then the sensor can function, but dirt can enter through the openings to cause misjudgment or failure
Solution Approach 1:
Light-transmissible windows serve as intermediary elements that selectively allow light signals to pass through while blocking dirt particles. These windows resolve the contradiction by providing a differential permeability solution - transparent to light but opaque to contaminants.
Solution Approach 2:
The light-transmissible windows function as thin film structures that maintain the enclosed protection of the housing while allowing optical signals to pass. This flexible approach to protection enables the sensor to function reliably without compromising the sealed environment.
3Reliability
If the housing is made fully enclosed for protection, then dirt ingress is prevented, but light signals cannot pass through for sensing operation
Solution Approach 1:
The housing is designed with different local properties: most portions are opaque and protective, while specific localized areas contain light-transmissible windows. This local quality differentiation allows the housing to provide overall protection while enabling light signal transmission at critical points for sensor operation.
Solution Approach 2:
The housing material properties are varied spatially - opaque in protective regions and transparent in regions requiring light transmission. This variation in optical properties (analogous to color changes) allows simultaneous achievement of protection and signal transmission 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 enclosed accommodation spaces and light shielding materials effectively protect the sensor components from dirt and ambient light, enhancing the accuracy and reliability of proximity status detection by maintaining signal integrity and reducing misjudgments.
Implementation Method 1
a sealed first light passage made of a first light-transmissible material, the first light passage being provided for the light signal reflected by an object to pass through
Implementation Method 2
the housing includes a portion made of the light-transmissible material whose surface is partially covered by a light shielding material
Data Source
AI summary
A proximity sensor includes: a transmitter unit for transmitting a light signal; a receiver unit for receiving the light signal reflected by an object to determine a proximity status of the object; and a housing defining a first enclosed accommodation space for accommodating the receiver unit, wherein the portion of the housing which defines the first enclosed accommodation space has a sealed light passage made of a light-transmissible material such that the receiver unit is capable of receiving the light signal reflected by the object through the light passage. The housing can further include a second enclosed accommodation space for accommodating the transmitter unit.