Display Apparatus Data Switching Circuit Reduces Flash Noise
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Solution Overview
Problem
Liquid crystal display (LCD) panels experience flash noise due to changes in common electrode voltage when power is turned on, affecting initial grayscale display and power consumption.
Innovation Solution
A display apparatus with a data switching circuit that outputs a common voltage to the data line during an initial setting period, ensuring both the common and pixel electrodes receive the same voltage, minimizing voltage differences and thus reducing flash noise, and includes a gate driver to output gate signals during this period, operating in a normally black mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the common electrode voltage is changed from ground voltage to common voltage when power is turned on, then the display panel can be driven, but flash noise occurs and random grayscale is displayed
Solution Approach 1:
The data switching circuit outputs the common voltage to the data line during an initial setting period before normal image data is input. This preliminary action ensures that both the common electrode and pixel electrode receive the same voltage (common voltage) during power-on, preventing voltage differences that would cause flash noise. The initial setting period allows the display panel to stabilize before displaying actual images.
2Power
If the common electrode voltage is changed when power is turned on, then the display panel can operate, but power consumption increases due to flash noise
Solution Approach 1:
The data switching circuit is configured to output the common voltage to the data line during an initial setting period when power is turned on, before normal image data is input. This preliminary action ensures that both the common electrode and pixel electrode receive the same voltage (common voltage) during power-on, preventing voltage differences that would cause flash noise and associated energy loss. The initial setting period allows the display panel to stabilize before displaying actual images, reducing overall power consumption.
3Object-affected harmful factors
If a data switching circuit is added to output common voltage during initial setting period, then flash noise is reduced, but device complexity increases
Solution Approach 1:
The data switching circuit is configured to output different voltages to the data line depending on the operating period. During the initial setting period, it outputs the common voltage to prevent flash noise. During the normal driving period, it outputs image data voltages for normal display operation. This multi-functionality allows a single circuit to serve both the flash noise reduction function and the normal data transmission function, minimizing the need for additional dedicated circuits.
Data Source
AI summary
A display apparatus includes a display panel including a switching element connected to a data line and a gate line, a pixel electrode connected to the switching element, a common electrode facing the pixel electrode and a liquid crystal layer disposed between the pixel electrode and the common electrode. The display apparatus further includes a data driving circuit configured to convert image data to a data voltage. The display apparatus further includes a driving voltage generator configured to generate a common voltage, in response to a voltage control signal from a timing controller, to the common electrode and the data driving circuit, which is configured to output the common voltage to the pixel electrode during an initial setting period when power is turned on to the display apparatus.