LCD Source Driver Power-Down Isolation to Prevent Display Noise
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Liquid crystal display (LCD) source drivers experience malfunction and produce abnormal images such as line defects or band mura during power supply on/off due to insufficient power, leading to noise output.
Innovation Solution
A source driver with a power down detector that asserts a reset signal to turn off the charge sharing switch and disconnect channels from output pads when the supply voltage is insufficient, preventing abnormal data transmission during power transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the source driver operates during power supply on/off, then the display can show images continuously, but the channels malfunction and produce abnormal images due to insufficient power
Solution Approach 1:
The power down detector detects power supply status in advance and asserts a reset signal before power becomes insufficient. This preliminary action prevents channel malfunction by proactively disabling the charge sharing switch and disconnecting channels from output pads, thereby maintaining reliable operation during power transitions
Solution Approach 2:
The system performs preliminary disconnection of channels from output pads via the multiplexer when power down is detected. This advance preparation ensures that no abnormal data is transmitted to the display during power transitions, resolving the contradiction between continuous operation and operational reliability
2Stability of the object's composition
If the charge sharing switch remains connected during power down, then voltage sharing between output pads is maintained, but noise is output and abnormal images appear on the display
Solution Approach 1:
The power down detector triggers disconnection of the charge sharing switch from the output pads when power supply insufficiency is detected. This extraction of the charge sharing function during critical power transitions eliminates the source of noise and abnormal images, while voltage stability is maintained through proper reset signaling
Solution Approach 2:
The multiplexer acts as an intermediary between channels and output pads. When power down is detected, the multiplexer disconnects the channels from the output pads, preventing abnormal data transmission. This intermediary mechanism resolves the conflict between maintaining voltage sharing and preventing noise output
Data Source
AI summary
The present invention discloses a source driver and a method for restraining noise output by a source driver during power on/off of a power supply. The source driver includes a multiplexer, at least two channels and at least two output pads. The channels are connected to the output pads via the multiplexer. The source driver is powered by a first supply voltage from the power supply. The two output pads are connected via a charge sharing switch. The method comprises the following steps. First, determine whether the first supply voltage is insufficient, and if yes, perform the following steps. Turn off the charge sharing switch. Then, disconnect the channels from the output pads by the multiplexer.