Display Driving Circuit Retaining Circuits Power-On Stability
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Solution Overview
Problem
Liquid crystal display devices with active-matrix panels face challenges in achieving a stable display at power-on due to indefinite potential states in retention capacitor wires, leading to increased circuit area requirements, making them unsuitable for narrow frame designs.
Innovation Solution
A display driving circuit with a shift register and retaining circuits that load and retain a control signal before the first vertical scanning period, eliminating the need for a separate control circuit to fix signal potentials on retention capacitor wires, thereby stabilizing the display without increasing circuit area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate control circuit is added to fix signal potentials on retention capacitor wires at power-on, then display stability at power-on is improved, but circuit area increases
Solution Approach 1:
The patent merges the control function for retention capacitor wire potential fixation into the existing shift register circuit by adding retaining circuits to specific stages. This integration eliminates the need for a separate control circuit, thereby improving display stability at power-on without increasing overall circuit area. The retaining circuits are incorporated into the scanning signal line driving circuit structure, sharing the same physical space and control infrastructure.
Solution Approach 2:
The patent applies preliminary action by having the retaining circuits load and hold the retention target signal before the first vertical scanning period begins. This pre-loading of control signals ensures that the retention capacitor wires receive the correct potentials immediately when needed, stabilizing the display at power-on without requiring additional control circuitry that would increase area.
2Length of stationary object
If the frame size is reduced for narrow frame design, then device compactness is improved, but circuit area for power-on control becomes insufficient
Solution Approach 1:
The patent enables narrow frame design by merging the power-on control functionality into the existing shift register circuit. The retaining circuits are integrated into the scanning signal line driving circuit, eliminating the need for separate control circuits that would consume valuable area in compact designs. This integration allows the frame size to be reduced while maintaining sufficient circuit area for all necessary functions.
3Device complexity
If retention capacitor wires are supplied with indefinite potentials immediately after power-on, then circuit simplicity is maintained, but display quality deteriorates
Solution Approach 1:
The patent resolves the contradiction by having the retaining circuits load the retention target signal before the first vertical scanning period. This preliminary action ensures that retention capacitor wires receive proper potentials immediately at power-on, preventing display quality deterioration. The solution maintains circuit simplicity because the retaining circuits are integrated into the existing shift register structure rather than adding separate control circuits.
Data Source
AI summary
A display driving circuit for driving a liquid crystal display panel includes a shift register including a plurality of shift register circuits provided in such a way as to correspond to a plurality of gate lines, respectively, the display driving circuit having latch circuits provided in such a way as to correspond one-by-one to the shift register circuits, a polarity signal being inputted to the latch circuits. When a internal signal generated by a shift register circuit becomes active, a latch circuit loads and retains the polarity signal, and an output from the latch circuit is supplied to a CS bus line. The internal signal becomes active before a first vertical scanning period of a display picture.