Electrostatic Pen Diode Switch for Accurate Position Detection
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Solution Overview
Problem
Conventional electrostatic pens using MOS or bipolar transistors for information transmission suffer from low accuracy due to high stray capacitance, leading to increased bit error rates and inability to detect position accurately when information transmission is not continuous, and they cannot perform multilevel modulation.
Innovation Solution
An electrostatic pen with a switch section comprising a diode and a reverse-current preventing unit, allowing for controlled potential differences to manage current flow and enable accurate information detection and multilevel modulation by switching between on and off states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a MOS transistor is used as the switch for changing conduction state between the pen point electrode and the main body, then the information transmission capability is improved, but the stray capacitance becomes very high (e.g., 10 pF), which reduces the accuracy of information detection in the position detecting device
Solution Approach 1:
The patent changes the electrical parameters of the switching element from a MOS transistor with high stray capacitance to a diode with low stray capacitance. By selecting a different component type with fundamentally different electrical characteristics, the patent achieves low stray capacitance (enabling accurate position detection) while maintaining the switching functionality needed for information transmission.
2Adaptability or versatility
If the switch is turned off to transmit information, then the current path is interrupted and information can be transmitted through current changes, but position detection becomes impossible during the period when information transmission is not performed
Solution Approach 1:
The patent ensures continuous position detection capability by maintaining the diode in a forward-biased state during normal operation, which keeps the current path intact for position detection. Information transmission is achieved by controlled switching that temporarily interrupts this path, but the system is designed so that position detection can resume immediately after transmission, ensuring both functions can operate continuously without mutual interference.
3Adaptability or versatility
If conventional transistors are used for information transmission, then binary modulation is possible, but multilevel modulation cannot be performed due to the nature of transistor switching
Solution Approach 1:
The patent exploits the continuous controllability of diode conduction state (unlike binary transistor switching) to enable multilevel modulation. By varying the conduction level of the diode across multiple discrete levels, the system can transmit more information per signal cycle, achieving multilevel modulation capability that goes beyond simple binary on/off switching.
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
The solution increases the accuracy of information detection and allows for reliable position detection even when information transmission is not continuous, while enabling multilevel modulation for enhanced information transmission.
Implementation Method 1
a first diode having an anode connected to the first terminal part and having a cathode connected to the third terminal part
Implementation Method 2
The position detecting device includes, within a sensor surface, a plurality of X-direction electrodes each extending in an X-direction and a plurality of Y-direction electrodes each extending in a Y-direction
Implementation Method 3
a control section that controls the on-off state of the switch according to transmission information
Data Source
AI summary
An electrostatic pen has a switch, control circuitry to control the switch and a pen point electrode. The switch has first, second and third terminals and a first diode having an anode coupled to the first terminal and a cathode coupled to the third terminal. The pen point electrode is coupled to the first terminal of the switch. The control circuitry, in operation, supplies respective potentials to the second terminal and the third terminal of the switch and switches between two or more states including a first state in which a potential of the second terminal is higher than a potential of the third terminal and a second state in which the potential of the second terminal is equal to or lower than the potential of the third terminal.