Light Emission Controller for OLED Voltage Leakage
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Solution Overview
Problem
In organic light-emitting display devices, the voltage charged in a charging node for controlling light emission can leak due to parasitic capacitance, leading to unstable voltage output and deteriorated display picture quality.
Innovation Solution
A light emission controller with cascaded stages, each including a first node controller to charge a driving pulse to a set node and a second node controller to charge a pull-down voltage to a reset node, along with capacitors to maintain voltage levels and prevent leakage, ensuring stable output pulses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a light emission controller supplies active signal to pixels during time period except for data charging, then continuous light emission control is achieved, but voltage leakage occurs due to parasitic capacitance causing unstable output
Solution Approach 1:
The patent applies preliminary action by resetting the charging node voltage to a predetermined level before the active period begins. The light emission controller performs a reset operation during the data charging time period, proactively preventing voltage leakage issues that would occur during the subsequent active signal supply period. This preliminary reset ensures that when the active signal is supplied for continuous light emission control, the charging node starts from a known stable voltage state, thereby maintaining voltage stability throughout the duration of active signal supply.
2Reliability
If voltage is charged in charging node for light emission control, then light emission control function is achieved, but voltage leaks due to parasitic capacitance deteriorating display quality
Solution Approach 1:
The patent converts the harmful effect of parasitic capacitance-induced voltage leakage into a beneficial controlled process. Instead of trying to eliminate parasitic capacitance (which is inherent in the circuit), the invention utilizes the predictable charging and discharging behavior of the charging node through controlled reset operations. By intentionally managing the voltage state during the data charging period and resetting it to a predetermined level, the system transforms the potential harm of voltage leakage into a controlled voltage management strategy that ensures stable light emission control and prevents display quality deterioration.
Data Source
AI summary
A light emission controller includes: a plurality of stages, including: a first node (n1) controller charging a driving pulse of a gate-on voltage level to a set node (Q) by a reference clock pulse during an active period, a second node controller charging a pull-down voltage having the gate-on voltage level to a reset node during an inactive period, and an output unit controlled by voltage states of the Q and the reset node and outputting an active or inactive state output pulse, the n1 controller including: a first switching transistor supplying the driving pulse of the gate-on voltage level to n1 by the reference clock pulse during the active period, a second switching transistor supplying the driving pulse from n1 to the Q by a turn-on voltage, a first capacitor between the output unit and Q, and a second capacitor between the output unit and n1.