Sensor Panel Coil Width Gradient for Indication Error Reduction
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Solution Overview
Problem
Electromagnetic induction-type digitizers experience indication errors, particularly in the peripheral areas, leading to reduced effective operation screens and user difficulty in graphic design and other operations, due to lower signal intensity and S/N ratio as the electronic pen moves outside the central coil area.
Innovation Solution
A sensor panel configuration with a first sensor coil group at the center and a second sensor coil group at the periphery, where the second group has gradually shortened coil widths and a uniform coil side pitch, eliminating the need for dummy wires and enhancing the area for three-point supplementing while reducing indication errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the sensor coils are arranged with uniform coil width throughout the array, then the manufacturing process is simple, but the indication error increases in the peripheral area due to wider coil pitch at the ends
Solution Approach 1:
The patent applies local quality by differentiating coil widths based on spatial position. The first sensor coil group at the central part has a first coil width, while the second sensor coil group at the peripheral part has a second coil width that is narrower than the first. This local differentiation optimizes the coil pitch in the peripheral area to reduce indication error while maintaining uniformity in the central area for accurate coordinate detection.
2Area of stationary object
If the coil pitch is reduced at the peripheral area to reduce indication error, then the effective operation area increases, but the magnetic flux distribution becomes non-uniform
Solution Approach 1:
The patent implements local quality by spatially varying the coil width parameter. The peripheral sensor coils have narrower widths to reduce indication error and expand the effective operation area, while central sensor coils maintain standard widths to preserve uniform magnetic flux distribution. This localized optimization allows different regions to serve different functional requirements simultaneously.
3Stability of the object's composition
If dummy wires are added to maintain uniform magnetic flux at the periphery, then the magnetic flux distribution improves, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent extracts and eliminates the dummy wires from the sensor panel structure. Instead of adding dummy wires to compensate for the narrower coil widths at the periphery, the invention directly uses the narrowed coil width as the design feature, achieving uniform magnetic flux distribution naturally without requiring additional dummy wire elements.
Solution Approach 2:
The patent converts the potential harm of non-uniform magnetic flux distribution into a benefit by strategically narrowing the peripheral coil widths. This design choice naturally compensates for the reduced coil area at the periphery, creating uniform magnetic flux distribution that eliminates the need for dummy wires and simplifies the overall device structure.
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 enlarges the effective operation area, suppresses indication errors, and maintains uniform magnetic flux distribution, improving the accuracy of coordinate detection and user experience by reducing the impact of indication errors in peripheral regions.
Implementation Method 1
One of the operating principles of the digitizer is based on electromagnetic induction. Such an electromagnetic induction-type digitizer includes a coil array disposed at a sensor panel that detects the position of the electronic pen based on magnetic flux of electromagnetic waves propagating between the sensor panel and the electronic pen.
Data Source
AI summary
To reduce an indication error at a peripheral part of an electromagnetic induction type coordinate detection device, sensor coils having a coil width of 21 pitches are arranged at a central part at intervals of 4 pitches. At a peripheral part, the coil width is shortened from sensor coil #5 to coil #1 sequentially so that the coil width of a sensor coil is shorter than a coil width of an inwardly adjacent sensor coil by 2 pitches. This enables the coil side pitch that is 1 all over the coil group 222, and an area enabling three-point supplementing can be enlarged from the conventional one. The sensor coils at the peripheral part have a coil pitch of 3, and so an indication error there can be reduced compared with the conventional case of coil pitch of 4 for two-point supplementing as well. Dummy wires required at the peripheral part conventionally can be eliminated.