Display Control and Touch Detection Device for Flicker Suppression
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Solution Overview
Problem
Existing display control and touch detection systems in portable information terminal devices face issues with noise interference between the display panel and touch panel due to capacitive coupling, leading to undesired brightness differences and flicker, especially when touch detection is frequent or continuous.
Innovation Solution
A display control and touch detection device that dynamically adjusts the start timings of display and non-display terms based on touch detection results, using multiple frame modes to optimize timing and reduce noise interference, allowing for flexible control of display and touch detection actions within each display frame period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If touch detection is performed frequently or continuously during display terms, then touch detection precision is improved, but noise interference increases causing brightness differences and flicker
Solution Approach 1:
The patent implements periodic touch detection by dividing the display frame period into multiple display terms and non-display terms. Touch detection is performed selectively in non-display terms rather than continuously, reducing noise interference while maintaining adequate touch detection capability. The detection timing is periodic and synchronized with the display frame structure.
Solution Approach 2:
The display frame period is segmented into distinct display terms and non-display terms. This segmentation allows separate optimization of display performance and touch detection performance, enabling touch detection to occur during non-display terms without affecting display quality, thereby reducing noise-induced brightness differences and flicker.
2Ease of operation
If display and non-display terms are repeated in a fixed cycle of frame synchronizing signal, then touch detection timing is regularized, but brightness differences and flicker become more remarkable
Solution Approach 1:
The patent introduces asymmetry in the arrangement of display and non-display terms within the display frame period. Rather than repeating a fixed symmetric pattern, the timings are adjusted to create asymmetric distributions that reduce visible brightness differences and flicker while preserving regular touch detection timing through synchronization with the frame synchronizing signal.
3Measurement precision
If drive pulse voltages are raised for activating scan electrodes of touch panel, then touch detection sensitivity is improved, but noise exerts adverse effect on liquid crystal panel through capacitive coupling
Solution Approach 1:
The patent extracts the touch detection function from the display operation by performing touch detection during non-display terms when the display panel is not actively driving scan electrodes. This separation removes the source of capacitive coupling noise from the touch detection process, allowing higher drive pulse voltages to be used during display terms without affecting touch detection quality.
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 effectively suppresses undesired brightness differences and flicker, allows for efficient data accumulation in buffer memory, and reduces power consumption by adjusting timing according to touch detection frequency, ensuring optimal display and touch detection performance.
Implementation Method 1
In a mutual capacitance type touch panel supporting a multipoint touch or the like, many detection capacitances are formed at intersecting points of drive and detection electrodes arranged to cross each other like a matrix
Implementation Method 2
a liquid crystal element and a storage capacitor which make a sub-pixel are connected between the drain and a common electrode, whereby respective pixels are formed
Data Source
AI summary
A display control and touch detection device is capable of controlling display and non-display terms in start timing depending on a result of touch detection, and includes a nonvolatile memory and a control logic which selectively uses data stored in the memory according to a display mode. The control logic changes the display and non-display terms in start timing in display frame periods, whereby the phenomenon of appearance of an undesired brightness difference at a fixed location in a display frame with no display, and the phenomenon of occurrence of flicker owing to the undesired brightness difference can be suppressed. Based on the result of touch detection, the control logic changes the way to use data which decide start timings of display and no display. The start timings of display and non-display terms in a display frame period can be changed depending on the result of touch detection readily.