Buffer Circuit Bias Control for Display Noise Reduction
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Solution Overview
Problem
The existing data driving devices for display panels experience significant noise issues due to instantaneous power consumption, which can lead to defects and image quality problems in display devices, primarily because of the propagation of noise through shared ground components.
Innovation Solution
A data driving device is designed with a latch circuit, digital-to-analog conversion circuit, buffer circuit, and output switch to minimize noise generation and propagation by varying the bias voltage and current within a horizontal time period, using a buffer circuit to control the magnitude of the bias voltage and amplify the analog signal while adjusting the slew rate, and an output switch to manage the connection between the data line and the buffer circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the data driving device changes the data voltage supplied to the display panel according to grayscale values, then the brightness control of pixels is improved, but noise is generated due to instantaneous power consumption increase
Solution Approach 1:
The buffer circuit performs preliminary action by pre-charging or pre-discharging the data line to a target voltage level before the actual data voltage transition. This reduces the instantaneous current spike that would otherwise occur during voltage switching, thereby minimizing noise generation while maintaining the ability to drive pixels to desired brightness levels.
Solution Approach 2:
The data driving device employs periodic action by controlling the timing of voltage transitions to occur during specific horizontal time periods when the display panel is being refreshed. By synchronizing voltage changes with the display refresh cycle and using controlled timing sequences, the device manages power consumption fluctuations and noise generation in a periodic manner that minimizes interference with image quality.
2Reliability
If the data driving device supplies data voltage to drive pixels, then the display function is achieved, but noise propagates along the ground affecting other components
Solution Approach 1:
The buffer circuit acts as an intermediary between the data voltage source and the data line. It isolates the ground noise generated during voltage transitions from propagating to other circuit components by providing a localized charging path through its internal capacitance, thereby protecting the rest of the system from noise while maintaining reliable display operation.
3Productivity
If the data driving device changes data voltage at the start of each horizontal time period, then the grayscale update is achieved, but instantaneous power consumption increases causing noise
Solution Approach 1:
The buffer circuit performs preliminary voltage preparation by maintaining the data line at appropriate voltage levels during the horizontal time period. This preliminary action allows the grayscale update to be achieved without requiring large instantaneous power changes, as the buffer has already prepared the necessary voltage conditions in advance.
Solution Approach 2:
The buffer circuit employs dynamic operation by adjusting its output impedance and charging current based on the required voltage transition. During grayscale updates, the buffer dynamically controls the rate of voltage change on the data line, allowing fast updates when needed while minimizing power consumption during stable periods, thus resolving the contradiction between update speed and energy loss.
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
This solution effectively reduces the intensity and propagation of noise, thereby minimizing defects and improving image quality by controlling the bias current and voltage during data voltage changes, reducing the impact of instantaneous power consumption on the display device.
Implementation Method 1
a digital-to-analog conversion circuit configured to convert a digital signal corresponding to the pixel image data into an analog signal using a plurality of gamma voltages
Implementation Method 2
a buffer circuit configured to vary the magnitude of a bias voltage within one horizontal time period and to transfer the analog signal for driving a pixel to the pixel
Implementation Method 3
The buffer circuit is configured to reduce the magnitude of a bias current according to the bias voltage during a first time period of the one horizontal time period
Implementation Method 4
an output switch configured to control a connection between a data line connected to the pixel and the buffer circuit
Data Source
AI summary
An embodiment provides a data driving device that varies a bias current of an amplifier to prevent noise generated when a digital-to-analog conversion circuit converts a digital signal for a grayscale value into an analog signal from being propagated to a pixel.