Smoke Detector Sensor Chamber PCB Integration
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Solution Overview
Problem
Conventional smoke alarms face challenges in detecting smoke evenly due to obstructed airflow by components on the PCB, leading to variable detection times based on smoke direction and increased manufacturing complexity.
Innovation Solution
A smoke alarm design featuring a sensor chamber with vents around its periphery, where the PCB is sandwiched between two chamber parts, allowing smoke to flow through a planar path and reducing the need for components on both sides of the PCB, resulting in a slimline profile and lower manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If components are mounted on the PCB to detect smoke, then smoke detection function is achieved, but the components obstruct smoke flow and cause variable detection times
Solution Approach 1:
The sensor chamber is divided into two portions by the PCB, with the sensor positioned at the edge where it can detect smoke from either side. This segmentation allows smoke to access the sensor from multiple directions, reducing detection time variability caused by obstruction from other components.
2Reliability
If the sensor is placed on the opposite side of the PCB with attachments providing smoke flow path, then smoke detection is improved, but housing design complexity and manufacturing cost increase
Solution Approach 1:
The sensor chamber portions and PCB are merged into a single integrated assembly where the PCB serves both as a structural support and as a divider within the sensor chamber. This eliminates the need for separate attachments to create smoke flow paths, reducing housing design complexity and manufacturing cost.
3Reliability
If attachments are added to create smoke flow path around attachments, then smoke ingress is improved, but alarm profile becomes bulky and obtrusive
Solution Approach 1:
The sensor is positioned at the edge of the PCB, allowing it to detect smoke from both sides of the board in three-dimensional space. This dimensional arrangement eliminates the need for bulky attachments, maintaining a slimline alarm profile while ensuring reliable smoke ingress from any direction.
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 ensures even responsiveness to smoke from any direction, reduces manufacturing complexity and costs, and enhances the slimline profile while maintaining efficient smoke detection.
Implementation Method 1
sensor means mounted within the sensor chamber; an alarm circuit including detection means for detecting said smoke when sensed by the sensor means
Data Source
Figure 1~2
Figure 3~4
Figure 5~6a
AI summary
An alarm for detecting smoke comprises a housing (1) having vents (9) for allowing ingress of smoke into the housing. A sensor chamber (22,26) is disposed within the housing and has vents (24a,24)b for allowing ingress of smoke into the sensor chamber and comprises two parts. A diode emitter and diode sensor (25) is mounted within the sensor chamber for sensing light reflected off smoke. An alarm circuit (32), including detection means for detecting smoke sensed by the sensor diode (25), is supported on a printed circuit board (PCB) (29). The PCB is sandwiched between two halves (22 and 26) of the sensor chamber such that an edge (30) thereof extends part-way into said sensor chamber. The sensor is mounted on, near or adjacent to the edge.