LED Display Drive Switching Device Threshold Voltage Restoration
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Solution Overview
Problem
The drive switching device in light emitting diode display devices degrades over time due to increased threshold voltage in one direction, affecting the intensity control of the driving current.
Innovation Solution
A light emitting diode display device design that includes a signal transmission switching device, a drive switching device, a control switching device, and a storage capacitor, where the control switching device connects the gate line to the node with a second gate low voltage having a polarity opposite to the data signal, preventing degradation by maintaining the node at a negative polarity and allowing the drive switching device to restore its threshold voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the drive switching device controls the intensity of driving current using a data signal with constant polarity, then the light emitting diode can be driven effectively, but the threshold voltage of the drive switching device increases in one direction causing device degradation
Solution Approach 1:
The patent applies periodic action by introducing a dual-gate low voltage signal that alternates between first and second gate low voltages with opposite polarities. This periodic switching restores the threshold voltage of the drive switching device by applying compensating voltages in alternating directions, preventing the cumulative threshold voltage shift that occurs with constant polarity data signals.
Solution Approach 2:
The patent changes the voltage parameter by introducing a second gate low voltage with polarity opposite to the data signal. This parameter change allows the control switching device to apply a compensating voltage that counteracts the threshold voltage increase, thereby restoring and stabilizing the drive switching device's threshold voltage while maintaining driving current control capability.
2Device complexity
If a conventional drive switching device structure is used without additional control mechanisms, then the device complexity is low, but the drive switching device degrades over time affecting operational lifespan
Solution Approach 1:
The patent segments the gate control function into two independent parts: a data signal applied to the first gate electrode for driving current control, and a dual-gate low voltage signal applied to the second gate electrode for threshold voltage restoration. This segmentation allows each gate to perform its specific function independently, extending device lifespan without significantly increasing overall structural complexity.
Solution Approach 2:
The patent introduces a control switching device as an intermediary component that receives the dual-gate low voltage signal and conditions it before applying it to the second gate electrode. This intermediary structure enables precise control of the threshold voltage restoration process while maintaining a relatively simple overall device architecture.
3Loss of information
If the node is maintained at positive polarity during data signal transmission, then data can be written effectively, but the drive switching device threshold voltage increases causing degradation
Solution Approach 1:
The patent applies preliminary anti-action by using the control switching device to preemptively counteract the threshold voltage increase caused by positive polarity data signals. The dual-gate low voltage signal with opposite polarity is applied in advance or concurrently to prevent cumulative threshold voltage shift, thereby maintaining reliability during data transmission operations.
Data Source
AI summary
The present disclosure relates to a light emitting diode display device which can prevent a drive switching device from degrading. The light emitting diode display device includes a plurality of pixel cells each having a light emitting diode, a plurality of data lines for transmission of data signal having information on a picture, a plurality of gate lines for transmission of a gate signal having a gate high voltage, a first gate low voltage, and a second gate low voltage having a polarity opposite to the data signal, wherein the gate high voltage, the first gate low voltage and the second gate low voltage having potentials different from one another wherein each of the pixel cells includes a signal transmission switching device for connecting the data line to a node according to the first gate high voltage from the gate line, a drive switching device for controlling an intensity of a drive current being supplied to the light emitting diode according to a signal state of the node, a storage capacitor connected between the node and a source electrode or a drain electrode of the drive switching device, and a control switching device for connecting the gate line to the node in response to the second gate low voltage from the gate line and a control signal from a control line.