Proximity Sensor Under Display Screen Reducing Crosstalk
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Solution Overview
Problem
The placement of a proximity sensor behind a display screen in electronic devices, such as smartphones, leads to unwanted diffraction effects due to the display screen, causing crosstalk and degrading the performance of the proximity sensor, especially when using OLED screens.
Innovation Solution
The proximity sensor is positioned under the display screen with its optical light emitter and detector aligned at an acute angle relative to the pixel orientations, ensuring that none of the pixels used for emission and reception are in the same row or column, and the common axis between the emitter and detector is offset by an angle between 10° and 80° to minimize diffraction-induced crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the proximity sensor is placed behind the display screen to increase display area, then the display screen area is increased, but diffraction effects cause crosstalk that degrades proximity sensor performance
Solution Approach 1:
The patent applies asymmetry by orienting the row and column directions of the pixel matrix at non-standard angles (e.g., 25 degrees from horizontal and vertical references). This asymmetric pixel orientation breaks the symmetry of diffraction patterns that would otherwise align with the emitter-detector axis, thereby reducing crosstalk while preserving the benefit of placing the sensor behind the display.
Solution Approach 2:
The patent introduces a new dimensional parameter: the angular orientation of the pixel matrix relative to the emitter-detector axis. By controlling the angle between the pixel row/column directions and the optical path, the patent transforms a two-dimensional problem (sensor placement) into a three-dimensional solution involving angular orientation, thus reducing diffraction-induced crosstalk.
2Device complexity
If the proximity sensor is positioned with emitter and detector aligned perpendicular to the display screen, then the optical path is simplified, but diffraction from pixel structures causes unwanted optical reflections
Solution Approach 1:
The patent applies asymmetry by orienting the row and column directions of the pixel matrix at non-standard angles (e.g., 25 degrees from horizontal and vertical references). This asymmetric pixel orientation breaks the symmetry of diffraction patterns that would otherwise align with the emitter-detector axis, thereby reducing crosstalk while preserving the benefit of placing the sensor behind the display.
Solution Approach 2:
The patent changes the angular parameters of the pixel matrix orientation relative to the optical path. By adjusting the angles of the row and column directions (e.g., setting them at 25 degrees from reference axes), the patent modifies the diffraction pattern characteristics to minimize unwanted reflections while maintaining a relatively simple optical path configuration.
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 significantly reduces the crosstalk effect, enhancing the performance of the proximity sensor by minimizing unwanted optical reflections and improving the accuracy of proximity sensing.
Implementation Method 1
an unwanted diffraction of the light passing through a display screen, for instance through an OLED screen, has been observed when the light is emitted and received by the proximity sensor through the display screen
Implementation Method 2
the optical detector picks up the emitted light after being reflected by a target object through the display screen again
Data Source
Figure 1A~1B
Figure 1C
Figure 2
AI summary
The present disclosure relates to an assembly (200) for an electronic device, the assembly comprising: - a display screen (110) comprising a plurality of pixels arranged in a matrix scheme comprising rows orientated in a first direction (X) and columns orientated in a second direction (Y); and - a proximity sensor (220) comprising at least one optical light emitter (222), each adapted to emit a light beam through one or more first pixels of the display screen, and an optical detector (224) adapted to receive through one or more second pixels of the display screen the light beam emitted by the at least one optical light emitter and reflected on an object; wherein none of the one or more second pixels is in the same row as any of the one or more first pixels, and none of the one or more second pixels is in the same column as any of the one or more first pixels.