Smoke Sensor Case Labyrinth Structure Light Blocking
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Solution Overview
Problem
The existing smoke sensors, such as those described in JP 2010-257258 A, face challenges in smoothly detecting smoke due to the flow of smoke into the optical base, leading to potential detection errors.
Innovation Solution
A smoke sensor design featuring a sensor case with a labyrinth structure that allows smoke to pass through while reducing incident light transmission, including a blocking region and inhibiting walls to control smoke inflow, ensuring the photodetector unit receives scattered light effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sensor case has a simple open structure to allow smoke to pass through freely, then smoke detection responsiveness is improved, but incident light transmission increases causing detection errors
Solution Approach 1:
The patent introduces an intermediary structure (the sensor case with specific wall configuration) between the external environment and the optical base. This intermediary structure selectively allows smoke to pass through while blocking incident light from reaching the optical base, thereby resolving the contradiction between smoke detection responsiveness and light interference prevention.
Solution Approach 2:
The sensor case employs local quality differentiation through its wall structure: certain regions are designed with smoke-permeable properties while simultaneously maintaining light-blocking characteristics. The blocking region with inhibiting walls creates localized zones that control smoke flow while preventing light transmission, allowing different parts of the structure to serve different functions.
2Ease of manufacture
If the sensor case structure is simplified to reduce manufacturing complexity, then manufacturing cost is reduced, but smoke flow control capability deteriorates
Solution Approach 1:
The sensor case is segmented into distinct functional regions: a blocking region with inhibiting walls that controls smoke flow, and a light-shielding region that prevents light transmission. This segmentation allows each region to be optimized for its specific function while maintaining overall manufacturing feasibility through modular design principles.
3Measurement precision
If the photodetector unit is positioned to receive direct light for high sensitivity, then detection sensitivity is improved, but false detection from direct light increases
Solution Approach 1:
The sensor case acts as an intermediary that modifies the light path before it reaches the photodetector unit. By blocking direct light transmission while allowing scattered light from smoke to reach the detector, the structure enables the photodetector to maintain high sensitivity for smoke detection without being triggered by direct light, thus preventing false detections.
Solution Approach 2:
The patent converts the potentially harmful effect of light into a beneficial one by designing the optical path so that only scattered light from smoke particles can reach the photodetector. This transforms what would normally be a source of false detection into a mechanism that enhances smoke detection specificity, as the photodetector responds only to light that has interacted with smoke particles.
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 enhances the ability of the photodetector unit to detect smoke smoothly by controlling smoke flow and preventing detection errors caused by uneven smoke distribution, thereby improving the accuracy of smoke detection.
Implementation Method 1
a photodetector unit disposed at a position where the light emitted from the light-emitting unit is not incident directly and where scattered light that has been scattered by smoke in the sensing space is incident
Data Source
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AI summary
An object of the present disclosure is to provide a smoke sensor that allows a photodetector unit thereof to detect smoke smoothly. A smoke sensor (1) according to the present disclosure includes: a sensor case (21) surrounding a sensing space (Sp1); a light-emitting unit (22) that emits light toward the sensing space (Sp1); and a photodetector unit (23) disposed at a position where the light emitted from the light-emitting unit (22) is not incident directly and where scattered light that has been scattered by smoke in the sensing space (Sp1) is incident. The sensor case (21) has a wall structure (labyrinth structure 24) that lets the smoke pass through and reduces transmission of incident light. The sensor case (21) also has a blocking region (25) provided locally along a circumference, surrounding the sensing space (Sp1), of the sensor case (21) to prevent the smoke from passing through. The sensor case (21) further has a first region (26) and a second region (27) provided on both sides of the blocking region (25) along the circumference of the sensor case (21) to let the smoke pass through. The sensor case (21) further includes an inhibiting wall (5) reducing inflow of the smoke from either the first region (26) or the second region (27) and arranged to extend outwardly from the sensor case (21).