Segmented Transmitter Electrodes for Capacitive Proximity Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Capacitive sensing in input devices integrated with display devices faces challenges due to high capacitive load from TFT structures, limiting the capability for sensing hovering objects and requiring wide input dynamic range, which is not feasible with traditional mutual capacitance measurements.
Innovation Solution
The method involves segmenting transmitter electrodes and using switches to control their plane area, allowing for both absolute and transcapacitive sensing modes, where only a portion of the electrodes are used for absolute capacitance measurements to reduce capacitive load and enable two-dimensional proximity sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If sensing electrodes are placed close to TFT structures within the display device, then the capacitive sensing device can be integrated into the display device, but the sensing electrodes have a high capacitive load which limits the capability for sensing hovering objects
Solution Approach 1:
The transmitter electrode is divided into multiple segments (first transmitter electrode segment and second transmitter electrode segment) that can be independently controlled. This segmentation allows the system to selectively activate only the necessary electrode segments for absolute capacitance sensing, thereby reducing the total capacitive load while maintaining integration within the display device structure.
2Measurement precision
If absolute capacitance measurements are taken from sensing electrodes with high capacitive load, then hovering objects can be detected, but a wide input dynamic range from the analog front-end is required which is not feasible
Solution Approach 1:
Instead of using the full sensing electrode area for absolute capacitance measurements, the patent applies partial action by using only a portion of the transmitter electrode segments. This reduction in active sensing area decreases the capacitive load to a manageable level that does not require an excessively wide input dynamic range from the analog front-end, while still enabling effective hovering object detection.
3Adaptability or versatility
If sensor electrodes are driven by digital logic distributed between components of a processing system, then the sensing device can be integrated with the display device, but the sensor electrodes are not available for absolute capacitance measurements by receiver module IC
Solution Approach 1:
The electrode is segmented into multiple independent sections that can be selectively driven by different control mechanisms. This allows the receiver module IC to access and drive specific transmitter electrode segments for absolute capacitance measurements, while other segments remain under digital logic control for transcapacitive sensing, thus resolving the conflict between integration and measurement capability.
Solution Approach 2:
The system dynamically switches between different operating modes: transcapacitive sensing mode driven by digital logic and absolute capacitance sensing mode driven by the receiver module IC. This dynamic reconfiguration allows the same physical electrode structure to serve multiple functions at different times, maintaining both integration and 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 approach enhances the ability to detect and track hovering objects by reducing capacitive loading and allowing for robust transcapacitive sensing, while maintaining efficient operation and power management in input devices.
Implementation Method 1
Capacitive sensing devices, when integrated partially or completely within a display device such as a tablet, touch screen or smart phone
Implementation Method 2
the sensor electrodes used for transmitting signals for obtaining mutual capacitance measurements
Data Source
AI summary
Embodiments described herein include a method and apparatus for capacitive sensing in input devices integrated with a display device. In one example, an input device is provided that includes a display device, a plurality of transmitter electrodes integrated with the display device, and a processing system. The plurality of transmitter electrodes include at least a first transmitter electrode and a second transmitter electrode. The first transmitter electrode includes a plurality of transmitter electrode segments. The plurality of transmitter electrode segments includes at least a first transmitter electrode segment connectable with a second transmitter electrode segment. The processing system is configured to: when operating in a first mode, simultaneously drive the first transmitter electrode segment and the second transmitter electrode segment connected as the first transmitter electrode, and when operating in a second mode, drive the first transmitter electrode segment separately from the second transmitter electrode segment.