Touch Display Capacitor Compensation for Stable Touch Sensing
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Solution Overview
Problem
Touchscreen performance deteriorates due to increased distance between touch sensing and drive electrodes, leading to reduced capacitance values and potential malfunctions during touch sensing.
Innovation Solution
A touch display device with a substrate, light-emitting elements, encapsulation units, and a compensation circuit that includes a second mutual capacitor with a higher capacitance value, connected in parallel to the first mutual capacitor, to compensate for capacitance deviations and prevent malfunctions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If touch lines are added to connect touch sensing electrodes and touch drive electrodes, then the touchscreen can function properly, but the distance between electrodes increases and capacitance value decreases
Solution Approach 1:
The patent divides the capacitance compensation function into two parts: the first mutual capacitor in the active area provides basic touch sensing, while the second mutual capacitor in the non-active area provides additional capacitance. This segmentation allows each capacitor to have optimized dimensions and positioning, resolving the contradiction between connectivity and capacitance value.
Solution Approach 2:
The patent moves the second mutual capacitor from the active area to the non-active area, utilizing the unused peripheral space. This dimensional relocation allows the touch lines to connect electrodes without reducing the overlapping area of the primary sensing capacitor, thereby maintaining capacitance value while ensuring functionality.
2Ease of operation
If the distance between touch sensing electrode and touch drive electrode is increased due to touch lines, then electrode connectivity is achieved, but mutual capacitor capacitance value is reduced
Solution Approach 1:
The patent merges the functionality of multiple capacitors by connecting the first mutual capacitor (in active area) and the second mutual capacitor (in non-active area) in parallel. This combination allows the system to achieve both electrode connectivity through touch lines and maintain sufficient total capacitance value for reliable touch sensing.
Solution Approach 2:
The patent creates a second mutual capacitor that copies the structure and function of the first mutual capacitor, but places it in the non-active area. This copied capacitor provides additional capacitance in parallel, compensating for the capacitance reduction caused by increased electrode distance in the primary sensing path.
3Device complexity
If capacitance value of mutual capacitor is lower than self-capacitor, then circuit simplicity is maintained, but touchscreen malfunction occurs
Solution Approach 1:
The patent changes the capacitance parameter by adding a second mutual capacitor in parallel, which increases the total mutual capacitance value. This parameter change ensures that the mutual capacitance exceeds the self-capacitance, preventing touchscreen malfunction while maintaining circuit simplicity through the use of additional capacitor structures rather than complex control circuits.
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 enhances touch performance by maintaining consistent capacitance values between touch sensing and drive electrodes, preventing malfunctions and improving sensitivity.
Implementation Method 1
the first and second compensation electrodes being configured to form a second mutual capacitor, whereby the value of capacitance of all mutual capacitors is increased
Data Source
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AI summary
A touch display device includes a touch sensing electrode and a touch drive electrode disposed on an encapsulation unit configured to encapsulate a light-emitting element, the touch sensing electrode and the touch drive electrode being configured to form a first mutual capacitor, and first and second compensation electrodes disposed in a non-active area of a substrate so as to be opposite each other, the first and second compensation electrodes being configured to form a second mutual capacitor, whereby the value of capacitance of all mutual capacitors is increased, and therefore it is possible to prevent deterioration in touch performance.