Electromagnetic Pointer Incline Angle Determination via Auxiliary Signal Sampling
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Solution Overview
Problem
Conventional methods for determining the incline angle of an electromagnetic pointer are inaccurate and complex due to variations in distance between the pointer and the digitizer, especially when the pointer tilts only along the y-axis.
Innovation Solution
The method involves sampling voltage signal distributions from sensor coils on both sides of the center coil to calculate the incline angle, avoiding the center coil to prevent errors caused by distance variations, and using the ratio or difference of auxiliary peak values to determine the angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the main peak values and auxiliary peak values of the induction voltage signal distribution are used to calculate the incline angle, then the incline angle can be obtained, but the accuracy is affected by distance variations between the electromagnetic pen and the digitizer
Solution Approach 1:
The patent extracts and excludes the center antenna signal from the incline angle calculation process. By removing the center antenna (which corresponds to the main peak) from the calculation, only the auxiliary peak values from surrounding antennas are used. This extraction eliminates the harmful effect of distance variations that primarily affect the center antenna signal strength, while preserving the angular information contained in the auxiliary peak distribution pattern.
Solution Approach 2:
The patent applies different treatment to different parts of the signal distribution. The center antenna signal is excluded from calculation, while only the auxiliary antenna signals are utilized. This local differentiation allows the system to ignore the portion of the signal (center antenna) that is most affected by distance variations, while utilizing the portion (auxiliary antennas) that contains the necessary angular information with less distance sensitivity.
2Measurement precision
If the ratio of main peak induction-voltage to auxiliary peak induction-voltage is used for angle calculation, then the incline angle can be determined, but the calculation complexity and error increase due to location-dependent ratio variations
Solution Approach 1:
The patent extracts and removes the main peak (center antenna signal) from the calculation process. By excluding the center antenna and using only auxiliary peak values from surrounding antennas, the method eliminates the need for complex distance-dependent ratio calculations, thereby reducing computational complexity while maintaining angle determination capability.
3Measurement precision
If conventional signal processing methods are used, then the incline angle can be calculated, but the error increases when the electromagnetic pen is not close to the digitizer
Solution Approach 1:
The patent extracts and excludes the center antenna signal that is most sensitive to distance variations. By using only auxiliary peak values from surrounding antennas for angle calculation, the method achieves reliable incline angle determination regardless of the distance between the electromagnetic pen and the digitizer surface.
Solution Approach 2:
The patent applies selective signal utilization where auxiliary antenna signals are used for angle calculation while the center antenna signal is excluded. This local quality differentiation ensures that the calculation relies on signals that are less affected by distance variations, thereby improving reliability across different operating distances.
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 improves the accuracy of incline angle calculation by isolating the center coil's signal variations, providing a more reliable method for determining the electromagnetic pointer's angle without errors from distance changes.
Implementation Method 1
The conventional methods for determining the incline angle of an electromagnetic pointer disclosed in U.S. Pat. No. 5,751,229 and U.S. Pat. No. 5,748,110 involve the processing of signals emitted from an electromagnetic pen through signal amplifying, filtering, rectifying, phase detecting and analog to digital conversion to generate voltage signals
Data Source
AI summary
A method for determining an incline angle of electromagnetic pointer is disclosed. The method comprises the following steps. First of all, an electromagnetic input pen/stylus is provided over antennas Xn/Yn along X/Y axes. Then a plurality of antennas at two sides of the antennas Xn/Yn are scanned. Next the signal distributions of the antennas Xn/Yn and the antennas at two side are analyzed. Then the number of antenna sampled of the signal distributions of the antennas at two side is determined. Next the antennas at two side are selected and the signal distributions are sampled and received according to the number of antenna sampled. Finally, an incline angle of the electromagnetic pointer is determined according to the sampled signal distributions.