Pen Coordinate Detection with Tilt Correction
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Solution Overview
Problem
Conventional coordinate detection methods for pens on touch surfaces suffer from significant errors due to pen tilt, as they rely on correction tables that reference erroneously detected coordinates, leading to inaccuracies in correction amounts.
Innovation Solution
The method involves detecting pen coordinates and tilt data using linear electrodes, and referencing a correction table that defines correspondence between correction amounts and combinations of coordinates and tilt data, or correcting coordinates based on tilt data before referencing the table, to reduce errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional correction tables referencing only coordinates are used, then device complexity is reduced, but measurement precision deteriorates due to significant errors in correction amounts when the pen is tilted
Solution Approach 1:
The correction table is extended from a two-dimensional structure (coordinates only) to a three-dimensional structure by adding tilt angle as a third dimension. This allows the correction amount to be determined by combining coordinates (x, y) and tilt angle (θ), enabling accurate correction even when the pen is tilted. The correction table now stores correction amounts for various combinations of coordinates and tilt angles, resolving the contradiction between maintaining simple device structure and achieving high measurement precision.
2Reliability
If the pen tip electrode is made larger to provide sufficient capacitance, then signal detection capability is improved, but measurement precision deteriorates due to coordinate detection errors when the pen is tilted
Solution Approach 1:
The system measures the tilt angle of the pen and uses this information as feedback to select the appropriate correction amount from the correction table. By continuously monitoring the tilt state and adjusting the correction accordingly, the system compensates for the coordinate detection errors caused by the extended pen tip electrode, thereby maintaining high measurement precision while preserving sufficient signal detection capability.
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 significantly reduces errors in correction amounts outputted from the correction table by considering tilt data, improving the accuracy of pen position detection on touch surfaces.
Implementation Method 1
Signals to be detected may be pen signals transmitted from the pen through a pen tip electrode or signals for finger touch detection (signals generated in the position detection device). These two different types of signals are configured to flow between the pen and the position detection device through capacitance formed between the pen tip electrode and the linear electrodes.
Data Source
AI summary
A coordinate detection method includes detecting coordinates corresponding to a position of a pen tip electrode of a pen by detecting distribution of signal levels in a plane of a touch surface through use of a plurality of linear electrodes disposed in the plane of the touch surface; detecting tilt data indicating a tilt of the pen; and acquiring a correction amount corresponding to a combination of the coordinates and the tilt data by referencing a correction table defining a correspondence between correction amounts and combinations of coordinates and tilt data.