Touch Display Sensor Circuit Precharge Voltage Optimization
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Solution Overview
Problem
Existing display devices with touch panel functions face issues such as variation in sensor element characteristics due to manufacturing processes, non-sensing regions, and interference from electrostatic noises, leading to potential malfunction and increased costs associated with wide voltage ranges for accurate touch sensing.
Innovation Solution
The implementation of a display device with an insulating substrate, pixel blocks, sensor circuits, scanning lines, and signal lines, where a precharge voltage is used to enhance capacitance detection between a coupling electrode and detection electrode, and an antistatic layer and conductive paste are employed to manage surface charges and prevent false contact detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the voltage range inputted to the analog-to-digital converter is made greater to increase the absolute output voltage, then the touch sensing accuracy is improved, but the cost for the touch sensing is increased
Solution Approach 1:
The patent applies preliminary action by pre-charging the detection electrode to a predetermined voltage before touch detection. This precharge voltage establishes a baseline potential that allows the sensor to detect touch events with a limited voltage range ADC, eliminating the need for a high-voltage ADC while maintaining detection accuracy. The precharge is performed in advance through dedicated precharge lines and switches, preparing the sensor circuit in a known state before actual touch sensing begins.
2Adaptability or versatility
If sensor elements are built on the substrate which constitutes the display, then the touch panel function is integrated, but the characteristic of the sensor element shows variation depending on manufacturing processes and non-sensing regions are generated
Solution Approach 1:
The patent divides the display substrate into distinct functional regions: display pixel regions and sensor circuit regions. Sensor circuits are placed in specific areas (such as corners or edges) rather than uniformly across the entire display area. This segmentation allows independent optimization of display and sensing functions, reduces interference between them, and enables better control over manufacturing variations by isolating sensor elements from display fabrication processes.
Solution Approach 2:
The patent introduces dedicated precharge lines and switches as intermediary components between the signal source and the detection electrode. These intermediary elements provide a controlled pathway to establish the detection electrode voltage without requiring high-voltage ADC circuitry. The precharge switches act as intermediaries that connect or disconnect the precharge lines from detection electrodes based on timing signals, enabling precise voltage control.
3Adaptability or versatility
If the touch panel function is realized by building sensor elements on the display substrate, then integration is achieved, but the touch panel function may stop operating by changes of electrostatic noises in a using environment
Solution Approach 1:
The system performs preliminary action by continuously or periodically pre-charging detection electrodes to a known voltage state before touch detection. This precharge operation resets any electrostatic noise or charge accumulation that may have built up during operation, ensuring the detection electrode starts each sensing cycle in a known, stable state. This preliminary voltage establishment mitigates the effects of electrostatic noise from the operating environment.
Solution Approach 2:
The patent implements feedback mechanisms where the output from the ADC is processed to determine touch events, and this information feeds back into controlling the precharge switches and signal lines. The system monitors the detection electrode voltage and adjusts precharge timing and magnitude based on detected conditions, creating a closed-loop system that compensates for electrostatic noise and maintains reliable operation.
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 improves the accuracy and speed of touch position detection, reduces the risk of sensor malfunction, and lowers costs by optimizing the precharge voltage range and signal/noise ratio, while maintaining high sensing ability and reliability.
Implementation Method 1
an information of the contact position is detected by a capacitance change between the electrode and the finger
Implementation Method 2
a precharge voltage is supplied to a detection electrode in a predetermined period before a signal for driving the pixels is supplied
Data Source
AI summary
In one embodiment, a display device having a touch function includes an insulating substrate and a plurality of pixels formed on the insulating substrate and arranged in a matrix of rows and columns. The pixels form a plurality of pixel blocks formed of a plurality of rows and columns of the pixels. A sensor circuit is arranged in a space between adjacent pixels on the insulating substrate and includes a coupling electrode, a detection electrode arranged adjacent to the coupling electrode for forming a coupling capacitance therebetween, and a reading-out circuit to read out a potential of the detection electrode. At least one sensor circuit is arranged in each pixel block. The contact or non-contact by a fingertip or a nib is detected by a potential difference of the detection electrode.