AMOLED Driving Circuit Segmentation for Fast Charging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional AMOLED driving circuits experience low charging speed and long charging time, making them unsuitable for high-resolution and high-refresh-frequency displays due to the small current supplied and large capacitance of storage capacitors.
Innovation Solution
An AMOLED driving circuit comprising a control unit, a charging unit, and a driving unit, where the control unit adjusts current coefficients of transistors to increase the ratio of data current to driving current, allowing for faster charging by controlling current flow and voltage supply through a network of switching and driving transistors connected to a storage capacitor and light emitting device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a small current IDATA is supplied to charge the storage capacitor in conventional current type AMOLED, then the driving current IOLED remains within the operating current range of the OLED, but the charging speed becomes low and charging time becomes very long
Solution Approach 1:
The patent divides the pixel circuit into separate functional units: a driving unit with multiple transistors (T1-T6) that controls current flow, and a dedicated charging unit with transistors (T7-T10) that handles capacitor charging independently. This segmentation allows the charging path to use higher current without affecting the OLED's operating current, resolving the contradiction between charging speed and current control.
Solution Approach 2:
The patent introduces an intermediary charging unit that acts as a buffer between the data line and the storage capacitor. This charging unit can accept high current from the data line through transistors T7-T10, then release it slowly to the capacitor, mediating between the high current available for charging and the low current required by the OLED, thus enabling fast charging without compromising OLED operation.
2Stability of the object's composition
If the capacitance of the storage capacitor is increased to maintain voltage stability, then the charging time becomes especially very long at low gray levels, but the voltage stability is improved
Solution Approach 1:
The patent implements preliminary action by providing a dedicated charging path that activates before the display refresh cycle. The charging unit with transistors T7-T10 pre-charges the storage capacitor to the required voltage level before the OLED needs to display the image, ensuring voltage stability is achieved in advance rather than during the critical display period, thus avoiding long charging times during active display operation.
Solution Approach 2:
The patent makes the charging circuit dynamic by using control signals to selectively activate the charging transistors T7-T10 only when needed for capacitor charging. The circuit transitions between charging mode and display mode, allowing high current to flow into the capacitor only during the charging phase, thereby achieving fast charging without compromising voltage stability during the display phase when the same capacitor maintains stable voltage for the OLED.
3Productivity
If the refresh frequency is increased for high resolution displays, then the charging time budget per frame is reduced, but the display quality is improved
Solution Approach 1:
By segmenting the circuit into independent driving and charging units, the patent enables the charging operation to occur in parallel with or before the display refresh cycle. The charging unit can complete capacitor charging using high current from the data line, allowing the main display circuit to proceed with the refreshed data, thus supporting higher refresh frequencies without sacrificing charging time.
Solution Approach 2:
The patent changes the current parameter in the charging path by enabling high current flow through transistors T7-T10 during the charging phase, which is different from the low current operation required during normal display. This parameter change allows the charging process to complete quickly within the reduced time budget of high refresh frequency operation, while the OLED continues to operate at its required low current for quality display.
Data Source
AI summary
An AMOLED driving circuit, a driving method and a display device, wherein a control unit is connected to a data line and a control line, and is connected to a driving unit via first, second and third nodes; a charging unit is connected to the driving unit via the first node, and is connected to a first power source; the driving unit is connected to one end of a light emitting device, and is connected to the first power source; the other end of the light emitting device is connected to a second power source. The control unit controls a current so as to charge the charging unit through the driving unit, and controls the charging unit so as to supply a voltage to the driving unit through the first node, so that the driving unit is driven by the voltage and drives the light emitting device to emit light.