Active Stylus Frequency Multiplexing for Simultaneous Signal Reception
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Solution Overview
Problem
In in-cell capacitive touch LCD display panels, the VCOM layer can only perform touch detection or screen display functions at different times due to conventional active styluses outputting signals with different information at different times, resulting in incomplete signal reception.
Innovation Solution
An active stylus with an integrated circuit (IC) and transmitting circuit that modulates multiple signals with distinct frequencies, mixing them to create a mixed signal, which is then transmitted to a touch sensor for demodulation and processing, allowing simultaneous transmission and reception of various information types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the VCOM layer performs touch detection function only during specific TP intervals, then touch detection can be performed, but the screen display update function cannot be performed simultaneously and multiple information types cannot be received at the same time
Solution Approach 1:
The active stylus segments information transmission by assigning different information types to different frequency carriers. The first modulator modulates a first signal (e.g., position information) with a first frequency, and the second modulator modulates a second signal (e.g., pressure information) with a second frequency. This frequency segmentation allows the touch sensor to receive multiple information types simultaneously during the same detection interval, resolving the contradiction between versatility and the existing single-function detection framework.
Solution Approach 2:
The invention adds a frequency dimension to the signal transmission. Instead of transmitting multiple information types sequentially in time (one dimension), the system transmits them simultaneously on different frequency carriers (another dimension). The mixer combines these frequency-modulated signals, and the touch sensor's IC demodulates them by frequency, enabling simultaneous reception of multiple information types without increasing temporal complexity.
2Loss of information
If the conventional active stylus outputs signals with different information at different time points, then each signal can be transmitted clearly, but the VCOM layer cannot completely receive all signals due to limited detection time windows
Solution Approach 1:
The invention enables continuous transmission of multiple information types throughout the entire detection interval. Instead of outputting signals at discrete time points with gaps between them, the active stylus continuously transmits multiple frequency-modulated signals simultaneously. The first modulator and second modulator operate concurrently, and the mixer combines their outputs continuously, ensuring that all information is transmitted throughout the TP interval without loss.
Solution Approach 2:
The system changes the parameter of signal transmission from sequential time-based output to simultaneous frequency-based output. By modulating different information types with different frequencies and transmitting them together, the system eliminates the time loss associated with sequential transmission while preventing information loss through frequency multiplexing at the receiver端.
3Adaptability or versatility
If the VCOM layer is cut into sensors with the same size for both touch detection and screen display, then the structure is simplified, but the layer cannot perform both functions simultaneously
Solution Approach 1:
The active stylus and touch sensor system achieves multi-functionality by enabling the VCOM layer to simultaneously perform touch detection and receive multiple types of information signals. The frequency modulation and demodulation mechanism allows the same sensor structure to process both touch position detection and additional information (such as pressure, digital status) at the same time, making the system universal without requiring separate dedicated structures for different functions.
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
Enables the simultaneous transmission and reception of multiple information types, such as position, pressure, and digital status, overcoming the limitations of incomplete signal reception in conventional systems.
Implementation Method 1
a first modulator for modulating a first signal with a first frequency to generate a first frequency modulated signal
Implementation Method 2
a second modulator for modulating a second signal with a second frequency to generate a second frequency modulated signal
Implementation Method 3
a mixer coupled to the first modulator and the second modulator, and utilized for mixing the first frequency modulated signal and the second frequency modulated signal to generate a mixed signal having the first frequency and the second frequency
Implementation Method 4
a first demodulator for demodulating the mixed signal with a first frequency to generate a first frequency demodulated signal
Implementation Method 5
a second demodulator for demodulating the mixed signal with a second frequency to generate a second frequency demodulated signal
Data Source
AI summary
An active stylus, a touch sensor, and a signal transmission and sensing method are provided. The active stylus comprises: an integrated circuit (IC) and a transmitting circuit. The IC comprises: a first modulator, a second modulator, and a mixer. The first modulator is utilized for modulating a first signal with a first frequency to generate a first frequency modulated signal. The second modulator is utilized for modulating a second signal with a second frequency to generate a second frequency modulated signal. The mixer is coupled to the first modulator and the second modulator, and utilized for mixing the first frequency modulated signal and the second frequency modulated signal to generate a mixed signal having the first frequency and the second frequency. The transmitting circuit is coupled to the IC, and utilized for transmitting the mixed signal to the touch sensor.