PPG Sensor Shielding Structure for Light Crossover Isolation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The issue of light crossover between the optical device and photoelectric sensor in photoplethysmography sensors, which affects heart rate measurement precision and user experience, is prevalent in existing smartwatches and smart bands.
Innovation Solution
A photoplethysmography sensor design featuring a housing and cover plate with a shielding structure and light insulating plate to isolate the optical device and photoelectric sensor, utilizing grooves, coatings, and light-shielding rings to prevent light crossover, enhancing measurement precision and user experience.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the optical device and photoelectric sensor are disposed close to each other in the photoplethysmography sensor, then the device size is reduced, but light crossover between the optical device and photoelectric sensor occurs, deteriorating measurement precision
Solution Approach 1:
The patent divides the internal space of the photoplethysmography sensor into distinct regions using shielding structures. The optical device and photoelectric sensor are segmented into separate light zones, with light-blocking walls and shielding plates creating physical partitions that prevent light crossover while maintaining compact overall dimensions.
Solution Approach 2:
The patent introduces light-blocking walls, shielding plates, and reflective shields as intermediary elements between the optical device and photoelectric sensor. These intermediaries block and redirect light paths, preventing direct light crossover while allowing both components to remain in close proximity for compact design.
2Measurement precision
If light-blocking structures are added to prevent light crossover, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent integrates multiple shielding functions into unified structures. The housing structure itself incorporates light-blocking walls, and shielding plates are positioned to serve multiple purposes (blocking light, defining optical paths, and structural support). This merging reduces the number of separate components needed.
Solution Approach 2:
The shielding structures and light-blocking walls serve multiple functions simultaneously: they block light crossover, define optical paths, provide structural support for component mounting, and reduce the overall device volume. This multi-functionality reduces complexity by eliminating the need for separate dedicated structures for each function.
3Measurement precision
If the cover plate thickness is reduced to allow light transmission, then light crossover increases, but if thickness is increased to block light, then measurement precision deteriorates
Solution Approach 1:
The patent applies different optical properties to different regions of the cover plate and internal structures. The cover plate maintains thinness for light transmission in the first and second areas, while light-blocking walls and shielding plates are positioned in the third area to block light locally where needed, achieving both light transmission and light blocking requirements.
Solution Approach 2:
The patent addresses the light blocking problem by moving from a single-dimension solution (increasing cover plate thickness) to a multi-dimensional approach. Light-blocking walls and shielding plates are positioned at specific three-dimensional locations within the sensor housing to block light paths without requiring increased cover plate thickness, thus maintaining measurement precision.
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 solution effectively reduces light crossover, improving measurement precision and user experience by ensuring accurate heart rate detection and reducing power consumption.
Implementation Method 1
a first area, used by the optical device to emit the light outwards
Implementation Method 2
a second area, used by the photoelectric sensor to receive the external optical signal
Implementation Method 3
a shielding structure, configured to isolate light between the optical device and the photoelectric sensor
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A photoplethysmography sensor (100) and a terminal (10) are provided. The photoplethysmography sensor (100) includes a housing (102), a cover plate (101), an optical device (103), configured to emit light outwards, and a photoelectric sensor (105), configured to receive an external optical signal. The housing (102) and the cover plate (101) form enclosed space, and the optical device (103) and the photoelectric sensor (105) are accommodated in the enclosed space. The cover plate (101) includes a first area (1011) used by the optical device (103) to emit the light outwards and a second area (1012) used by the photoelectric sensor (105) to receive the external optical signal. The cover plate (101) further includes a third area (1013), a shielding structure is disposed on the third area (1013), and the shielding structure is configured to isolate light between the optical device (103) and the photoelectric sensor (105). The shielding structure is disposed in the third area (1013), so that isolation between the optical device (103) and the photoelectric sensor (105) is improved, a light crossover between the optical device (103) and the photoelectric sensor (105) is avoided, measurement precision of the photoelectric sensor (105) is improved, and user experience is improved.