Position Detecting Device with Peripheral Excitation Coil
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Solution Overview
Problem
Existing position detecting devices for liquid crystal displays face challenges in integrating transparent sensor coils on the front surface due to high resistance issues with ITO films, leading to increased manufacturing complexity and reduced battery life when used in mobile terminals.
Innovation Solution
A position detecting device with an excitation coil surrounding the periphery of the position detecting area supplies an excitation signal to the position indicator, and a controller dynamically adjusts the signal strength based on the detected position and signal level, allowing for optimized power consumption and extended battery life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If sensor coils are formed using ITO film to achieve transparency, then the transparency of the liquid crystal display is improved, but the electrical resistance increases making it difficult to transmit sufficient power to the position indicator
Solution Approach 1:
The patent divides the power transmission function from the sensor coils and assigns it to a separate surrounding coil. The sensor coils (formed by transparent ITO film) are dedicated to signal detection only, while the surrounding coil handles power transmission. This segmentation allows each component to be optimized for its specific function without compromise.
Solution Approach 2:
The surrounding coil acts as an intermediary component that provides the power transmission function that the transparent sensor coils cannot fulfill. This intermediary element enables the use of transparent materials for the sensor coils while maintaining adequate power transmission through a separate dedicated component.
2Use of energy by moving object
If sensor coils are arranged in the rear of the liquid crystal panel to avoid transparency issues, then power transmission is improved, but the manufacturing complexity and cost increase due to disassembly requirements
Solution Approach 1:
The patent segments the coil functions and positions them differently: sensor coils on the front surface and surrounding coil at the periphery. This spatial segmentation allows both transparency and power transmission requirements to be met while simplifying manufacturing, as the surrounding coil can be added without disassembling the liquid crystal panel.
Solution Approach 2:
The patent uses a separate surrounding coil that copies the functional role of power transmission from the sensor coils, allowing the sensor coils to be placed on the front surface for transparency while the surrounding coil handles power transmission at the periphery.
3Area of stationary object
If the position detecting area is made large to improve usability, then the operational area is improved, but the signal level received at the center becomes weak when the position indicator is located there
Solution Approach 1:
The patent separates the power transmission function (surrounding coil) from the signal detection function (sensor coils). The surrounding coil provides strong excitation signals that enable large detection areas, while the sensor coils maintain high sensitivity for precise position detection even at the center of the large detection area.
Solution Approach 2:
The surrounding coil serves multiple functions: it provides the excitation signal for position detection and compensates for signal strength variations across the detection area, enabling both large area coverage and maintained signal precision.
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 enables transparent sensor coils on the front surface of liquid crystal displays and extends battery life in mobile terminals by dynamically controlling the power consumption of the position detecting device.
Implementation Method 1
an excitation coil (19) arranged to surround a periphery of the position detecting area to supply an excitation signal to the position indicator (40)
Implementation Method 2
a position indicated by a position indicator is detected by providing a resonant circuit in the position indicator to transmit/receive electromagnetic waves between the position indicator and a tablet
Data Source
AI summary
An excitation coil (19) surrounding the periphery of the position detecting area is connected to an oscillating circuit (21), which oscillates at a frequency f0, through a drive circuit (20). A CPU (18) supplies control signals to a selecting circuit (12), a sample-and-hold circuit (16), an A/D conversion circuit (17), and the drive circuit (20). Based on the control signal output from the CPU (18), the drive circuit (20) controls the power of the signal output from the excitation coil (19) to ON or OFF. Further, the strength of the excitation signal supplied from the excitation coil (19) is controlled based on information obtained by analyzing a signal received from a position indicator (40), such as the position indicated by the position indicator on the position detecting area and/or a strength of the signal received from the position indicator.