Touch Display Power Management for Sleep Mode Initialization
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Solution Overview
Problem
Advanced in-cell touch (AIT) display devices experience malfunctions and display defects, such as screen whitening, due to abnormal power sequence operations during sleep mode, where USB power is supplied before or after main power, leading to incomplete initialization of touch/data drivers and improper voltage application to touch electrodes.
Innovation Solution
A touch display device with a multiplexer that selects between main and USB voltages, a microcontroller unit (MCU) to monitor and manage power supply sequences, and power management circuits to ensure proper initialization and operation of touch/data drivers and gate drivers, preventing display defects by ensuring timely and correct voltage application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If USB power is supplied first before main power in sleep mode, then power consumption is reduced by turning off main power, but touch/data driver cannot perform initialization process and malfunction occurs
Solution Approach 1:
The patent applies preliminary action by having the MCU check whether the timing controller has been properly initialized before enabling touch driving operations. The system pre-verifies the initialization state through a determination unit that checks if the timing controller is in an initialized state, and only if so, does it enable the touch driving signal output. This prevents malfunction by ensuring proper initialization sequence even when USB power is supplied first.
2Use of energy by stationary object
If main power is turned off to reduce power consumption in sleep mode, then energy saving is achieved, but timing controller cannot operate and touch driver malfunction occurs
Solution Approach 1:
The patent introduces an intermediary mechanism in the form of a determination unit that mediates between the power supply state and the touch driving operations. This determination unit checks the initialization state of the timing controller and controls the enablement of touch driving signals accordingly. This intermediary verification mechanism ensures that touch driving operations only occur when the timing controller is properly initialized, maintaining ease of operation while preserving power saving benefits.
3Use of energy by stationary object
If DC voltage is applied to touch electrodes due to abnormal operation, then power consumption is reduced, but liquid crystal turn-on state continues and display defects occur
Solution Approach 1:
The patent implements feedback by having the determination unit continuously monitor the initialization state of the timing controller and use this information to control the output of touch driving signals. The feedback mechanism ensures that touch driving signals are only output when the timing controller is properly initialized, preventing abnormal DC voltage application to touch electrodes that would cause liquid crystal turn-on states and display defects like screen whitening.
Data Source
AI summary
A touch display device can include a panel including touch electrodes; a touch/data driver to drive data lines and the touch electrodes of the panel, read out capacitance variations in the touch electrodes and output sensing data; a gate driver to drive gate lines of the panel; a timing controller to control display operations of the touch/data driver and the gate driver; a microcontroller unit (MCU) to control touch driving and sensing operations of the touch/data driver; a first power circuit to drive the timing controller and the gate driver using a main voltage supplied through a first power line; a multiplexer to output one of a universal serial bus (USB) voltage supplied through a second power line and the main voltage supplied through the first power line; a second power circuit configured to drive the touch/data driver, the gate driver and the MCU based on an output voltage from an output of the multiplexer; and a switch connected between the output of the multiplexer and the second power line, the switch being configured to switch the output of the multiplexer to the second power line.