Capacitive Position Mapping in Displacement Pointing Devices
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Solution Overview
Problem
Displacement type pointing devices for portable electronic devices face challenges in achieving high accuracy and providing an absolute position mapping mode with a one-to-one correspondence between the displaceable member and the cursor on the display, due to limited workspace and power constraints.
Innovation Solution
A pointing device with a sense system comprising a spatial arrangement of sense electrodes and a drive electrode, where a conductive coupling element on the displaceable member capacitively couples signals to the sense electrodes, allowing for accurate measurement and processing of absolute positions, enabling an absolute position mapping mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If displacement type pointing devices use small field of motion to meet portable device constraints, then device size and power consumption are reduced, but measurement precision and ability to provide absolute position mapping mode deteriorate
Solution Approach 1:
The sensing surface is divided into multiple discrete sensing elements arranged in a grid pattern, allowing precise determination of which specific element is being actuated. This segmentation enables absolute position mapping by directly correlating the actuated element with a corresponding display location, achieving high measurement precision within a compact form factor suitable for portable devices
Solution Approach 2:
The patent transitions from traditional continuous analog sensing to a discrete two-dimensional array of sensing elements. This dimensional approach allows the system to provide absolute position mapping mode where each sensing element corresponds to a specific location, enabling a one-to-one correspondence between physical device position and cursor position on display within a limited workspace
2Device complexity
If displacement type pointing devices use small field of motion, then device complexity is reduced, but the ability to provide absolute device-cursor mapping mode deteriorates
Solution Approach 1:
The sensing system with its array of discrete sensing elements is designed to support multiple mapping modes including absolute position mapping, relative mapping, and velocity mapping. This universal design allows the same hardware configuration to adapt to different operational requirements, providing versatility in mapping modes while maintaining relatively simple device structure suitable for portable electronic devices
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
The solution enables high-accuracy sensing and mapping of the displaceable member's position to the cursor, providing a one-to-one correspondence, enhancing user input precision and intuitive operation within limited device constraints.
Implementation Method 1
a conductive coupling element operable to capacitively couple signals from the at least one drive electrode to ones of the sense electrodes underlying the conductive coupling element
Data Source
AI summary
A displaceable member moves in an operational zone over a sense system that includes a spatial arrangement of sense electrodes and at least one drive electrode. A conductive coupling element of the displaceable member capacitively couples signals from the at least one drive electrode to ones of the sense electrodes underlying the conductive coupling element. A measurement system generates measurement signals indicating amounts of overlap between the conductive coupling element and ones of the sense electrodes. A processing system produces from the measurement signals an output signal with information conveying motion measures corresponding to absolute positions of the conductive coupling element in the operational zone. At least one regional sense electrode may include discrete electrically conducting sensing elements distributed across a respective region of the operational zone. The drive electrode may include discrete electrically conducting sensing elements interspersed among the sensing elements of the at least one regional sense electrode.