Pressure Sensor Under Backlight Panel for Display Illuminance
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Solution Overview
Problem
Conventional pressure sensors integrated into display modules reduce illuminance and complicate the manufacturing process, impairing yield due to their complex structure and placement over the backlight panel.
Innovation Solution
The pressure sensor is positioned under the backlight panel with a bottom electrode layer featuring sub-electrodes of varying areas, allowing precise calculation of applied pressure without affecting illuminance, as the sensor's design optimizes capacitance changes based on electrode area and distance from the geometric center.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the pressure sensor is integrated into the display module over the backlight panel, then pressure sensing function is achieved, but illuminance is reduced and manufacturing complexity increases
Solution Approach 1:
The pressure sensor is relocated from the front surface (over the backlight panel) to the rear surface (under the backlight panel) of the display module. This spatial repositioning in another dimension eliminates the obstruction of light transmission while maintaining the pressure sensing capability through the rear surface.
Solution Approach 2:
The pressure sensing function is separated from the light transmission path by placing the sensor in a different spatial location. The sensor structure is divided into independent electrode layers that can function independently from the display optical path, allowing both functions to coexist without interference.
2Adaptability or versatility
If the pressure sensor is integrated into the display module over the backlight panel, then pressure sensing function is achieved, but manufacturing process becomes complex and yield decreases
Solution Approach 1:
The pressure sensor electrodes are integrated with the existing display module electrode structures. The bottom electrode layer of the pressure sensor is combined with the touch controller electrode, and the top electrode layer is combined with the display pixel electrode, reducing the number of separate manufacturing processes.
Solution Approach 2:
The electrode layers serve multiple functions simultaneously: the bottom electrode layer acts as both the pressure sensor electrode and the touch controller electrode, while the top electrode layer serves as both the pressure sensor electrode and the display pixel electrode. This multi-functionality simplifies the overall device structure and manufacturing process.
3Ease of manufacture
If sub-electrodes have uniform area, then manufacturing is simplified, but pressure measurement precision decreases due to inconsistent capacitance changes
Solution Approach 1:
The sub-electrodes are designed with non-uniform areas according to their specific positions. Sub-electrodes closer to the center have larger areas while those at the edges have smaller areas. This local differentiation compensates for position-dependent capacitance variations, ensuring uniform pressure measurement sensitivity across all sub-electrodes.
Solution Approach 2:
The area parameter of the sub-electrodes is deliberately varied based on their positional parameters. By changing the area parameter in proportion to the distance from the geometric center, the capacitance change per unit pressure is equalized across all sub-electrodes, improving 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
This configuration enables precise pressure sensing without reducing illuminance and simplifies the manufacturing process by ensuring consistent capacitance changes across sub-electrodes, allowing accurate pressure measurement while maintaining display module brightness.
Implementation Method 1
the pressure sensor is disposed under the backlight panel... When an applied pressure is received by the front panel, a magnitude of the applied pressure is sensed by the pressure sensor
Implementation Method 2
An elastic polymer medium 110 with distributed metallic nanoparticles 112 is filled in the sealed chamber 102... the elastic polymer medium 110 is compressed. That is, the distance between the metallic nanoparticles 112 is changed in response to an applied pressure 116
Implementation Method 3
The pressure-sensitive cell 336 further comprises a force-sensitive resistive material 338. The electrical resistance of the pressure-sensitive cell is changed according to the amount of force applied thereto
Data Source
AI summary
A display module includes a front panel, a backlight panel, a pressure sensor and a panel frame. The front panel includes an array of display pixels. The backlight panel is disposed under the front panel. The pressure sensor is disposed under the backlight panel, and includes a top electrode layer, an interlayer and a bottom electrode layer. The bottom electrode layer includes plural sub-electrodes. If a first distance between a first sub-electrode and a geometric center of the bottom electrode layer is shorter than a second distance between a second sub-electrode and the geometric center, an area of the second sub-electrode is larger than an area of the first sub-electrode. The panel frame is disposed under the pressure sensor. When an applied pressure is received by the front panel, a magnitude of the applied pressure is sensed by the pressure sensor.