Sensing apparatus and method based on electromagnetic induction type
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Solution Overview
Problem
Conventional electromagnetic induction (EI) sensing systems require a large number of channels for input and output signals, leading to increased operational complexity and a burden on firmware, especially when multiple loop coils are used, making accurate input positioning challenging.
Innovation Solution
The proposed sensing apparatus employs a loop unit with sub-loops connected in series and an area determination loop unit to reduce the number of channels by determining input points based on signal magnitudes from adjacent loops, allowing for accurate input detection with fewer channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a large number of loop coils are used to improve input position accuracy, then measurement precision is improved, but device complexity increases due to the large number of channels required
Solution Approach 1:
Each loop coil is divided into two sub-loops that are connected in series. This segmentation allows the system to reduce the total number of channels required while maintaining the ability to detect electromagnetic signals for input position determination. The series connection of sub-loops creates a configuration where adjacent loops share common connection points, reducing redundant channels.
Solution Approach 2:
Adjacent loop coils are merged through series connection at their shared connection points. This merging reduces the total number of independent channels needed, as the connection points between adjacent loops serve dual purposes for both loops simultaneously, thereby simplifying the overall channel structure.
2Measurement precision
If a large number of loop coils are used to improve input position accuracy, then measurement precision is improved, but the burden on firmware increases due to increased number of operations
Solution Approach 1:
The segmentation of loop coils into series-connected sub-loops reduces the number of independent signal channels that require processing. This directly decreases the number of operations the firmware must perform to process electromagnetic induction signals, thereby reducing the computational burden on the firmware while maintaining position detection accuracy.
3Measurement precision
If a large number of loop coils are used to improve input position accuracy, then measurement precision is improved, but scanning time increases
Solution Approach 1:
By segmenting loop coils into series-connected sub-loops, the system reduces the total number of channels that need to be scanned. This segmentation strategy decreases the overall scanning time required to detect input positions across the touchscreen surface, as fewer independent channels require individual scanning operations.
4Device complexity
If the number of channels is reduced to simplify the system, then device complexity is reduced, but input position accuracy may deteriorate
Solution Approach 1:
The series connection of sub-loops within each loop coil creates a configuration that maintains electromagnetic induction capability while reducing channel count. This segmentation approach preserves the ability to detect input positions accurately even with fewer channels, as each series-connected sub-loop configuration continues to generate detectable electromagnetic signals.
Solution Approach 2:
The system uses the electromagnetic signals received from the series-connected sub-loops to determine input positions. The feedback mechanism processes the signals from the reduced number of channels to accurately identify touch or input positions, maintaining measurement precision despite the reduction in channel quantity.
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 reduces the number of channels required by approximately half, decreases the time for scanning, alleviates the burden on firmware, and enables more accurate input position determination while reducing the number of switches and driving current, thus simplifying the system and lowering costs.
Implementation Method 1
a voltage is controlled to be applied to a loop coil arranged on a circuit board to generate an electromagnetic field for propagation to an EI pen
Implementation Method 2
The electromagnetic field emitted by the EI pen may propagate back to the loop coil on the circuit board, thus enabling a determination of which position of the touchscreen the EI pen comes closest
Data Source
Figure 1~2A
Figure 2B
Figure 2C~3
AI summary
A sensing apparatus for determining an input point of a pen, the sensing apparatus comprising: a sensing loop unit, including a plurality of loops, configured to output a first signal in response to a signal received from the pen, wherein each of the plurality of loops includes two sub-loops separated by a predetermined distance; an area determination loop unit including at least one loop configured to output a second signal in response to the signal received from the pen; and a controller configured to determine a plurality of candidates of the input point based on the first signal and determine the input point from the plurality of candidates of the input point based on the second signal, wherein the two sub-loops are connected to each other in series, wherein one sub-loop of the two sub-loops is disposed inside of an area in which one loop of the area determination loop unit is disposed and another sub-loop of the two sub-loops is disposed outside of the area in which the one loop is disposed, and wherein each of the plurality of loops of the sensing loop unit is configured to determine the plurality of candidates of the input point. A corresponding method is provided as well.