Pressure Sensing Unit Channel Reduction via Sensor Merging
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Solution Overview
Problem
The existing pressure sensing units in touch input devices require a large number of channels, leading to increased complexity and size in the connection structure, which complicates the connection between the pressure sensing unit and the FPCB, and reduces sensitivity due to the increased number of pins and area required.
Innovation Solution
A touch input device with a pressure sensing unit that includes a central pressure sensor and multiple non-central pressure sensors, where the central pressure sensor is composed of multiple connected pressure sensors and the non-central sensors have smaller areas, forming a reduced number of channels connected to a pressure sensor controller, and are disposed between insulation layers to maintain sensitivity while reducing the number of channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of channels in the pressure sensing unit is increased to improve measurement precision, then the sensitivity is improved, but the device complexity and connection structure area increase
Solution Approach 1:
Multiple pressure sensing units are integrated into a single package structure, sharing common connection lines to the FPCB. The pressure sensors are arranged in a matrix pattern with shared row and column lines, reducing the total number of connection lines required while maintaining multiple sensing channels for improved measurement precision
Solution Approach 2:
The connection lines serve multiple functions by being shared among multiple pressure sensors. The same row and column lines are used to connect to multiple pressure sensing units, allowing a single connection structure to support multiple sensing channels simultaneously
2Measurement precision
If the number of pins on the pressure sensor controller is increased to support more channels, then the measurement precision is improved, but the area required for connection increases
Solution Approach 1:
Multiple pressure sensing units share common connection lines, merging the connection paths. Instead of having separate pins for each sensor, the system uses shared row and column lines that are multiplexed to connect to multiple sensors, significantly reducing the total connection area required on the FPCB
3Measurement precision
If the connection structure between pressure sensing unit and FPCB is made more complex to support additional channels, then the measurement precision is improved, but the ease of manufacture decreases
Solution Approach 1:
The pressure sensing array is segmented into a matrix pattern of row and column lines, allowing systematic connection to multiple sensors. This segmentation approach simplifies the manufacturing process by providing a regular, repeatable connection structure that can be easily fabricated using standard PCB routing techniques
Solution Approach 2:
The connection structure is designed to be universal, with standardized row and column lines that can connect to multiple pressure sensors in a systematic manner. This universal connection approach simplifies manufacturing by using consistent connection patterns across all sensors rather than custom complex routing
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 maintains the sensitivity of the pressure sensing unit while reducing the number of channels and simplifying the connection structure, improving signal-to-noise ratio, especially in edge regions, and minimizing the area and complexity of the connection lines.
Implementation Method 1
one central pressure sensor for detecting the pressure based on a change of capacitance in response to bending of the display panel and a plurality of non-central pressure sensors for detecting the pressure based on a change of capacitance
Data Source
Figure 1a
Figure 1b~3a
Figure 3b~4b
AI summary
A touch input device capable of detecting a touch pressure may be provided, that includes: a display panel; and a pressure sensing unit which is disposed under the display panel. The pressure sensing unit includes one central pressure sensor for detecting the pressure and a plurality of non-central pressure sensors for detecting the pressure. An area of each of the non-central pressure sensors is less than that of the central pressure sensor.