Adjustable Filter Touch Sensing Circuit for Multi-Object Detection
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Solution Overview
Problem
Existing touch sensing technologies face challenges in reducing the size and power consumption of display devices while effectively sensing multiple objects with different frequencies, particularly Styli and fingers, due to the need for multiple analog signal processing circuits and inefficient integration with digital signal processing.
Innovation Solution
Integration of adjustable filters in the analog signal processing circuit within the touch sensing circuit, allowing for frequency band changes based on object type, enabling simultaneous sensing of Styli and fingers with reduced circuit size and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple analog signal processing circuits are used to sense different frequency signals from different objects, then the sensing capability for multiple objects is improved, but the circuit size and device complexity increase
Solution Approach 1:
The patent implements a single analog signal processing circuit that can process multiple frequency signals by dynamically adjusting its filter characteristics. The circuit achieves multi-functionality by changing the center frequency and bandwidth of its bandpass filter based on the detected object type, eliminating the need for multiple dedicated circuits for different objects like fingers and stylus pens.
Solution Approach 2:
The patent employs dynamic adjustment of filter parameters (center frequency and bandwidth) in the analog signal processing circuit. The circuit transitions from static to dynamic operation by modifying its frequency response characteristics in real-time according to the detected touch object, enabling one circuit to adaptively handle multiple frequency ranges that would otherwise require separate fixed circuits.
2Measurement precision
If multiple analog signal processing circuits are used to recognize different touch objects, then the object recognition accuracy is improved, but the power consumption increases
Solution Approach 1:
The patent creates a universal analog signal processing circuit that can accurately recognize different touch objects (fingers, stylus pens) by dynamically adjusting its filter characteristics. This single multi-functional circuit replaces multiple dedicated circuits, maintaining high recognition accuracy while significantly reducing overall power consumption since only one circuit needs to operate at any given time.
Solution Approach 2:
The patent implements periodic adjustment of filter parameters based on the touch detection sequence. The circuit alternates between different filter configurations corresponding to different object types, using periodic switching to maintain readiness for multiple object types without continuously operating multiple circuits simultaneously, thereby reducing power consumption while preserving recognition accuracy.
3Measurement precision
If separate analog signal processing circuits are used for different driving modes, then the signal processing accuracy for each mode is improved, but the integration with digital signal processing deteriorates
Solution Approach 1:
The patent merges the analog signal processing circuit with the digital signal processing circuit into an integrated system. The analog circuit processes raw touch signals and performs initial frequency-based object classification, then passes processed data to the digital circuit for further analysis. This unified architecture improves integration between analog and digital domains while maintaining processing accuracy through coordinated operation.
Solution Approach 2:
The integrated circuit performs multiple functions: it operates in different driving modes (projection touch, contact touch), detects various object types (fingers, stylus pens), and interfaces with digital processing. This multi-functional integration eliminates the need for separate dedicated circuits for each mode, improving both integration and versatility simultaneously.
4Adaptability or versatility
If the size of the touch sensing circuit is increased to provide versatility for different protocols, then the adaptability to different protocols is improved, but the reduction in display device size becomes difficult
Solution Approach 1:
The patent implements a universal touch sensing circuit that supports multiple protocols (projection touch, contact touch) and detects various object types through dynamic filter adjustment. This single versatile circuit replaces what would otherwise require multiple protocol-specific circuits, achieving full protocol compatibility while minimizing the overall circuit area and enabling display device size reduction.
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 allows for accurate and efficient sensing of multiple frequencies, reducing the size and power consumption of display devices by utilizing a single analog signal processing circuit with adjustable filters, effectively handling different touch inputs.
Implementation Method 1
The adjustable filter may include a variable resistor or a variable capacitor. A resistance value or capacitance value of the adjustable filter may be changed in response to the controlling signal, thus changing a frequency pass band of the touch sensing signal.
Implementation Method 2
The adjustable filter may include a variable resistor or a variable capacitor. A resistance value or capacitance value of the adjustable filter may be changed in response to the controlling signal, thus changing a frequency pass band of the touch sensing signal.
Implementation Method 3
The touch panel generates capacitance between the driving electrode and the sensing electrode. A change in the capacitance may indicate a touch or approach of the external object.
Data Source
AI summary
The present embodiment may provide a touch sensing circuit including: an analog signal processing circuit including one or more adjustable filters configured to receive a touch sensing signal from a touch electrode of a panel and to transmit some of a frequency region of the touch sensing signal; and a touch control circuit configured to determine a change in capacitance of the touch electrode attributable to an object approaching the panel and to transmit a controlling signal to control the adjustable filters of the analog signal processing circuit. The adjustable filter of the present embodiment may include a variable resistor or a variable capacitor. A resistance value or capacitance value of the adjustable filter may be changed in response to the controlling signal, thus changing a frequency pass band of the touch sensing signal.