Active Matrix Display Driver Initialization Circuit
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Solution Overview
Problem
Existing active matrix organic electroluminescent (EL) display devices face issues with variability in brightness and residual images of moving pictures, which are difficult to adjust without physically modifying the wiring, leading to increased costs and manufacturing time.
Innovation Solution
The introduction of a control circuit that utilizes a vertical start pulse signal to adjust the light-emitting period of organic EL devices, allowing for flexible control of the pulse width without altering the photomask, and the use of pre-charge and storage capacitor control pulses to initialize the driver transistor characteristics, enabling precise control over light-emitting periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the light-emitting period is fixed by hardware wiring, then the display device can be manufactured with standard processes, but the light-emitting period cannot be adjusted without physical wiring modifications
Solution Approach 1:
The patent makes the light-emitting period adjustable by using a control circuit that can dynamically change the pulse width of the pixel selection signal, replacing the fixed hardware wiring approach with a flexible software-controlled solution
Solution Approach 2:
The invention changes the parameter of light-emitting period from a fixed hardware-determined value to a variable parameter that can be adjusted by modifying the pulse width of the pixel selection signal through the control circuit
2Object-affected harmful factors
If the light-emitting period is extended to reduce residual images, then moving picture quality improves, but brightness variation increases
Solution Approach 1:
The control circuit adjusts the pulse width parameter of the pixel selection signal to optimize the light-emitting period, finding the optimal balance between reducing residual images and maintaining brightness uniformity
Solution Approach 2:
The control circuit can adjust the pixel selection signal timing based on feedback about display performance, optimizing the light-emitting period to simultaneously reduce residual images and maintain consistent brightness
3Adaptability or versatility
If wiring modifications are made to adjust the light-emitting period, then the light-emitting period can be changed, but development time and costs increase
Solution Approach 1:
The patent replaces the mechanical/wiring-based method of setting the light-emitting period with an electronic control method using a control circuit that adjusts the pixel selection signal timing, eliminating the need for physical wiring modifications
Solution Approach 2:
The invention enables parameter adjustment of the light-emitting period through software/control signals rather than hardware modifications, significantly reducing development time and costs
Data Source
AI summary
A variation in a display image and duration of a residual image are reduced to improve quality of display of an active matrix type display device. A control circuit sequentially outputs a pre-charge pulse signal PCG1 and a storage capacitor control pulse signal SC1 in synchronization with a falling edge of a vertical start pulse signal STV. A pre-charge TFT in a pixel in a first row is turned on according to the pre-charge pulse signal PCG1. As a result, a source and a gate of a driver TFT are short-circuited, both an electric potential at the gate and an electric potential at the source of the driver TFT become a positive power supply electric potential PVdd, and the driver TFT is turned off. After that, the storage capacitor control pulse signal SC1 rises to a high level, and the electric potential at the gate of the driver transistor is raised by capacitive coupling. With this, electric characteristics of the driver TFT are initialized.