Proximity Sensor Layout with Sound Output Unit for Crosstalk Reduction
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Solution Overview
Problem
Conventional proximity sensors in mobile terminals face issues with crosstalk due to internal diffuse reflection and reduced light transmission and reception, especially when the sensor window appears black on white devices, affecting aesthetic design and accuracy.
Innovation Solution
The proximity sensor is configured with a light-emitting unit and a light-receiving unit disposed on opposite sides of a sound output unit, utilizing a reflector with inclined reflecting planes and a cover unit with a lattice hole to increase light transmission and reduce crosstalk, allowing light to pass through for improved sensing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the light-emitting unit and light-receiving unit are located close to each other, then the device complexity is reduced, but crosstalk occurs due to internal diffuse reflection
Solution Approach 1:
A light shield is introduced as an intermediary element positioned between the light-emitting unit and light-receiving unit. This light shield blocks stray light and prevents internal diffuse reflection from causing crosstalk, while allowing the units to remain in close proximity for compact design.
Solution Approach 2:
The harmful effect of internal diffuse reflection is extracted and isolated by positioning the light-emitting and light-receiving units at opposite sides of a sound output unit, separating their optical paths and eliminating crosstalk interference.
2Shape
If a sensor window is stacked on the proximity sensor, then the aesthetic appearance is improved by matching the terminal color, but the amount of light emitted and received is reduced
Solution Approach 1:
The cover unit is designed with a lattice structure containing multiple holes. This porous-like structure allows a significant portion of infrared light to pass through while maintaining the visual appearance of a solid colored surface, thus preserving both aesthetics and light transmission performance.
Solution Approach 2:
The cover unit has different local properties: it appears opaque or translucent in visible light (matching terminal color for aesthetics) but is transparent to infrared light (allowing sensor operation). The lattice hole structure creates this selective optical property.
3Shape
If a white layer is directly printed on a film layer under the glass cover, then the aesthetic appearance is improved, but reflection and diffuse reflection occur which deteriorates sensing accuracy
Solution Approach 1:
A light shield is positioned between the light-emitting unit and light-receiving unit to block stray light paths. This prevents reflection and diffuse reflection from reaching the sensor, eliminating the harmful optical effects while allowing the white layer to remain for aesthetic purposes.
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 prevents crosstalk and enhances the amount of light emitted and received by the proximity sensor, improving its performance and maintaining a visually appealing design for mobile terminals regardless of color.
Implementation Method 1
a reflector having a first reflecting plane configured to refract light emitted from the light-emitting unit and a second reflecting plane configured to refract light introduced into the light-receiving unit
Data Source
AI summary
One embodiment relates to a proximity sensor, a camera module comprising same, and a mobile terminal comprising same and comprises: a housing; a substrate disposed inside the housing; a sound output unit mounted on the substrate; a display unit disposed on the upper side of the housing; a camera module comprising a proximity sensor, which comprises a light-emitting unit and a light-receiving unit and detects the proximity of a user to the display unit at a predetermined distance by having the light-emitting unit and the light-receiving unit disposed at either side of the sound output unit, and a control unit for receiving the amount of light emitted by the light-emitting unit and the amount of light received by the light-receiving unit as inputs from the proximity sensor so as to operate the display unit; and a cover unit disposed on the display unit and provided over the sound output unit and the proximity sensor.