Display Demultiplexing Circuit Control Line Voltage Management
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Solution Overview
Problem
The existing display apparatus using oxide-based thin film transistors faces challenges with low electron mobility and degradation, leading to difficulties in maintaining high-resolution image display and causing luminance issues due to off currents in organic light emitting diodes, while also increasing the bezel area and reducing reliability.
Innovation Solution
A display apparatus with a demultiplexing circuit portion that enhances the discharge function of control lines using a voltage controller, switching portion, and voltage discharge portion, implemented through a back channel etch process, to improve pixel charging rates and prevent off currents, thereby maintaining stable output and minimizing bezel area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If oxide based thin film transistor is used in demultiplexing circuit, then device complexity is reduced and bezel area is minimized, but electron mobility is lower and degradation occurs leading to unstable output
Solution Approach 1:
The patent applies preliminary action by pre-charging the control line to a high voltage level before the demultiplexing operation. A charge transistor is configured to charge the control line in advance during a pre-charge period, ensuring that when the oxide TFT switches activate, the control line already has sufficient voltage to maintain stable operation despite the lower electron mobility of oxide-based transistors.
Solution Approach 2:
The patent changes the voltage parameter of the control line dynamically. The control line voltage is adjusted between a first voltage level (during pre-charge) and a second voltage level (during operation), allowing the oxide TFTs to operate reliably. This parameter change compensates for the degradation and low mobility characteristics of oxide-based transistors.
2Ease of manufacture
If oxide based thin film transistor is used in demultiplexing circuit, then manufacturing process is simplified, but degradation occurs causing off current to transfer to organic light emitting diode
Solution Approach 1:
The patent uses preliminary action to prepare the control line voltage before the demultiplexing circuit operates. The charge transistor charges the control line in advance to a high voltage level, ensuring that when data signals are routed through the oxide TFT switches, the control line maintains sufficient voltage to keep the switches properly closed, preventing off current from leaking to the OLED.
Solution Approach 2:
The patent implements a feedback mechanism where the state of the control line is continuously monitored and adjusted. The charge transistor activates based on the operational state of the demultiplexing circuit, automatically replenishing voltage on the control line as needed to maintain proper switch operation and prevent harmful off current.
3Device complexity
If data time division driving is used to reduce channels, then device complexity is reduced, but demultiplexing circuit performance deteriorates due to low electron mobility
Solution Approach 1:
The patent applies preliminary action by pre-charging the control line before data signals are transmitted through the demultiplexing circuit. This ensures that when multiple data signals are time-division multiplexed through the oxide TFT switches, the control line maintains sufficient voltage throughout the entire data transmission period, compensating for the slower switching speed of oxide-based transistors.
Solution Approach 2:
The patent maintains continuous useful action by keeping the control line charged throughout the data transmission process. The charge transistor operates continuously or periodically to maintain the control line voltage, ensuring that the oxide TFT switches remain in the proper state for continuous data signal routing without interruption or degradation in transmission performance.
Data Source
AI summary
A display apparatus is disclosed, which comprises a demultiplexing circuit portion for sequentially supplying data signals supplied from a data driving circuit to at least two data lines, the demultiplexing circuit portion including a switching portion for sequentially supplying the data signals to at least two data lines based on a voltage of a control line, a voltage controller for controlling the voltage of the control line in response to a time-division control signal and an auxiliary signal partially overlapped with the time-division control signal, and a voltage discharge portion for discharging the voltage of the control line in response to the time-division control signal. Therefore, an off current capable of being transferred to an organic light emitting diode may be prevented from occurring, a bezel area may be minimized, and an image of high resolution of a display panel may be embodied.