Touch Panel State Restoration for ESD Latch-Up
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Solution Overview
Problem
Projected capacitive touch panels (PCT) are prone to malfunctions and potential destruction due to electrostatic discharge (ESD), which can cause latch-up phenomena leading to incorrect coordinate information and equipment malfunctions.
Innovation Solution
A touch panel device with a state sensing unit and state restoration unit that detects abnormal states and temporarily stops outputting touch information to prevent host equipment malfunction and restore the touch panel to a normal state, preventing destruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the power supply is turned off to restore a latched-up semiconductor integrated circuit, then the latch-up phenomenon is eliminated and the circuit returns to normal state, but information about capacitance values and coordinates is lost
Solution Approach 1:
The patent applies preliminary action by storing capacitance values and coordinate information in a backup storage unit before turning off the power supply to restore the circuit. This ensures that the information is preserved and can be restored after the circuit returns to normal operation, preventing data loss while eliminating the latch-up phenomenon.
2Productivity
If the touch panel continues to output touch information during abnormal state, then real-time touch detection is maintained, but host equipment may malfunction due to incorrect coordinate information
Solution Approach 1:
The patent implements feedback by having the control unit monitor the operational state of the semiconductor integrated circuit and automatically adjust the output behavior. When an abnormal state is detected, the control unit stops outputting touch information to prevent incorrect data from reaching the host equipment, thereby maintaining system reliability while preserving the ability to resume normal operation.
3Speed
If the touch panel device restores operation immediately after power supply interruption, then quick recovery is achieved, but the latch-up phenomenon may recur and cause further damage
Solution Approach 1:
The patent applies beforehand cushioning by introducing a predetermined waiting period before restoring power supply to the semiconductor integrated circuit after an abnormal state. This delay allows the circuit to fully settle and prevents the latch-up phenomenon from recurring, thereby protecting the device from further damage while still achieving relatively quick recovery.
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
Prevents host equipment malfunction and touch panel destruction by temporarily halting output during abnormal states and restoring the touch panel, ensuring accurate coordinate information and prolonged device lifespan.
Implementation Method 1
a plurality of sensors within a touch sensor panel are electrically connected to a semiconductor integrated circuit of a complementary metal oxide semiconductor (CMOS) structure that detects a capacitance
Implementation Method 2
The ESD occurs because, for example, static electricity excessively charged in a user's body is applied to the touch panel via a user's finger
Data Source
AI summary
In a touch panel device, an output control unit controls a process of outputting touch information acquired by a sensing unit and a touch detection unit of a touch sensor panel to host equipment, where the information indicates presence or absence and a coordinate of a touch of an indicator to the touch sensor panel. A state sensing unit senses an operation state of the sensing unit or the touch detection unit. A state restoration unit restores the sensing unit or the touch detection unit in the abnormal state to a normal state, based on a detection result of the state sensing unit. Upon detecting an abnormal state in the state sensing unit, an output control unit stops an output of the touch information to the host equipment for a fixed period of time.