Capacitive Pen Position Detection with Multi-Code Signal Segmentation
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Solution Overview
Problem
Conventional electrostatic coupling type position detection apparatuses can only detect position information and cannot detect additional information such as pressure, rotational position, or pen down information, and they are unable to simultaneously detect different pointers like a pen and a finger.
Innovation Solution
The position detection apparatus uses codes with a correlation matching operation to detect not only position information but also additional information like pressure, rotational position, and inclination, and it can simultaneously detect different pointers by using a pointer with a transmission signal production section that produces signals based on two codes with a time difference associated with pressure, and a sensor section with multiple conductors and a correlation matching operation circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If a conventional electrostatic coupling position detection apparatus uses a single signal transmission method, then the device complexity is low, but the information detection capability is limited to position only
Solution Approach 1:
The transmission signal is segmented into multiple codes (first code and second code) with different code patterns. The first code is used for position detection while the second code is used for detecting additional information such as pressure, rotational position, and pen down status. This segmentation allows the system to detect multiple types of information simultaneously without requiring separate detection systems for each parameter.
Solution Approach 2:
The patent introduces a time dimension by transmitting codes with different time differences. The time difference between the first code and second code varies according to the pressure applied to the pointer. This temporal dimension allows the system to encode multiple pieces of information (position, pressure, rotational position) within a single signal transmission sequence, thereby increasing information detection capability without proportionally increasing device complexity.
2Loss of information
If the position detection apparatus uses multiple codes with time difference for detecting additional information, then the information detection capability is improved, but the processing time increases
Solution Approach 1:
The system uses periodic transmission of code sequences where the first code and second code are transmitted in a repeating pattern. The correlation matching operation circuit processes these periodic signals to extract position and additional information. By using periodic action, the system can detect multiple types of information within each transmission cycle, reducing the overall processing time compared to sequential detection methods.
3Adaptability or versatility
If the sensor section uses a fixed conductor configuration, then the device complexity is low, but the ability to detect multiple different pointers simultaneously is limited
Solution Approach 1:
The patent introduces a switching section that dynamically changes the connection configuration of the conductor group based on the type of pointer detected. When a finger (body pointer) is detected, the switching section connects conductors in a configuration suitable for body capacitance detection. When a pen pointer is detected, the switching section switches to a configuration optimized for pen detection. This dynamic reconfiguration allows the system to detect multiple different types of pointers simultaneously while maintaining relatively simple hardware architecture.
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 solution allows for the detection of multiple types of information beyond just position, enabling more nuanced interaction with the position detection system, and allows for simultaneous detection of different pointers, enhancing usability and functionality.
Implementation Method 1
a position detection apparatus of the electrostatic coupling type includes, as principal components thereof, a pointer including an integrated circuit (IC) and a position detector including a sensor section having a group of conductors arrayed in a predetermined pattern. A predetermined signal is transmitted from the pointer, which is placed on the sensor section, to the conductor group
Data Source
AI summary
A pen-shaped position indicator is configured to capacitively couple with a sensor surface of a position detection apparatus. The indicator includes a pen-shaped body; a coil; a driving power production circuit configured to produce a DC voltage from an induced signal in the coil by a wireless interaction with a charging device; a signal production circuit connected to the driving power production circuit and configured to generate a signal based on the DC voltage to form a capacitive relationship between the pen-shaped body and the position detection apparatus; a first electrode; and a second electrode. The first and second electrodes are configured to form first and second capacitive relationships with the sensor surface, respectively, to generate detection signals in the sensor surface from which a first detection signal and a second detection signal distinguishable from each other are extracted and used to obtain angle information of the pen-shaped position indicator.