Display Control Device Reducing Voltage Load on Circuit Nodes
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Solution Overview
Problem
In portable information terminal devices with integrated display and touch panels, noise coupling between the display and touch panels leads to excessive voltage loads during non-display drive terms, causing degradation of display performance and unevenness in gradation signals.
Innovation Solution
A display control and touch control device that alternates between display and non-display drive terms, reducing the operation source voltage during non-display drive terms to prevent excessive voltage loads on circuit nodes, thereby avoiding temporal damage to the panel module.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the shift clock is stopped during non-display drive term to prevent gate line selection, then touch sensing can be performed, but the output of shift stage remains fixed causing excessive voltage load on driver input and degradation of display performance
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the operation source voltage based on the drive term. During non-display drive terms, the operation source voltage is reduced to a lower level, which prevents excessive voltage load on the driver input while still allowing the shift stage output to remain fixed for touch sensing. This voltage parameter adjustment resolves the contradiction between maintaining touch sensing capability and preventing voltage-induced degradation.
2Object-affected harmful factors
If the operation source voltage is reduced during non-display drive term, then voltage load on circuit nodes is prevented, but display performance may be affected
Solution Approach 1:
The patent implements periodic action by alternating between display drive terms and non-display drive terms in a cyclic manner. During display drive terms, normal operation source voltage is applied for optimal display performance. During non-display drive terms, the operation source voltage is reduced to prevent voltage load accumulation. This periodic switching allows the system to maintain display performance during active periods while preventing cumulative voltage damage during inactive periods.
Solution Approach 2:
The operation source voltage parameter is dynamically changed based on the drive term type. The control device adjusts the operation source voltage to a lower level during non-display drive terms, which prevents excessive voltage load on circuit nodes. This parameter adjustment is made in a controlled manner that does not adversely affect display performance when the display is actually active.
3Reliability
If the non-display drive term is made longer to improve touch sensing, then more time is available for touch detection, but voltage load on circuit nodes increases
Solution Approach 1:
The patent resolves this contradiction by changing the operation source voltage parameter during non-display drive terms. Even when the non-display drive term is extended for touch sensing, the reduced operation source voltage prevents excessive voltage load accumulation on circuit nodes. This allows sufficient time for touch detection while maintaining safe voltage levels throughout the extended period.
Data Source
AI summary
Provided is a technique which enables the avoidance of a temporal damage to a panel module, and keeps a voltage load on a display panel circuit node from becoming excessively large even if a constant voltage is applied to the node for a longer time exceeding a display drive term in a non-display drive term, provided that a display frame period is divided to have display and non-display drive terms. In performing display and touch-sensing actions on condition that a display frame period is divided to include display and non-display drive terms, an operation source voltage supplied to a panel module during the non-display term where touch sensing is performed is smaller, in absolute value, than that supplied in the display term, whereby a voltage load applied to an input circuit node of a panel module for a longer time exceeding the display term is kept from being excessively large.