Active Matrix Display Column Electrode Calibration Voltage Programming
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Active matrix display devices face long programming times due to low current signals and large voltage spreads, leading to inefficiencies in high-resolution displays.
Innovation Solution
The implementation of a calibration phase where a well-defined calibration voltage is applied to each column electrode before the programming current, maintaining this voltage until the programming current is applied, allowing for faster current programming and reducing dependence on the power supply voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If current programming is used for display pixels, then the display can be driven with low current signals, but the programming time becomes excessively long
Solution Approach 1:
The patent applies preliminary action by establishing a well-defined voltage level on column lines before applying programming currents. The display controller pre-charges or pre-discharges column lines to a specific voltage level (e.g., ground or a reference voltage) before the programming phase begins. This preliminary voltage establishment eliminates the need for long programming times to charge line capacitances, as the voltage is already defined and stable when programming currents are applied.
Solution Approach 2:
The patent employs preliminary anti-action by counteracting the voltage spread and instability on column lines before programming currents are applied. By pre-establishing a controlled voltage level and using calibration phases, the system prevents the harmful voltage variations from developing during programming, thereby eliminating the need for extended programming times to compensate for these variations.
2Device complexity
If programming current is applied without calibration, then the process is simpler, but voltage spreads result in long programming times
Solution Approach 1:
The patent introduces a calibration phase as a preliminary action before the actual programming phase. During this calibration phase, the display controller applies calibration voltages to column lines to establish well-defined voltage levels. This additional step, while increasing process complexity, dramatically reduces programming time by eliminating voltage spread issues, making the overall process more efficient.
Solution Approach 2:
The patent changes the voltage parameter on column lines from an uncontrolled state to a well-defined calibrated state before programming. By introducing calibration voltages and maintaining them during programming, the system transforms the electrical parameters of column lines to ensure stable, predictable voltage levels, thereby reducing programming time despite the added complexity.
3Loss of time
If calibration voltage is applied to each column electrode before programming, then programming time is reduced, but the process becomes more complex
Solution Approach 1:
The patent merges the calibration function into the existing display controller architecture, combining multiple functions (calibration voltage generation, column line control, and programming current delivery) into a single integrated controller. This consolidation reduces overall system complexity despite adding the calibration phase, as it eliminates the need for separate calibration hardware and simplifies the control architecture.
Solution Approach 2:
The display controller is designed with multi-functionality, serving both as a calibration voltage source and a programming current driver. The same column electrodes and control circuitry are used for both calibration and programming operations, eliminating the need for dedicated calibration hardware and reducing overall device complexity while still achieving reduced programming times.
4Manufacturing precision
If high resolution display is implemented, then display quality improves, but programming time increases due to more pixels
Solution Approach 1:
The patent applies preliminary voltage calibration to column lines before programming, which reduces the programming time per pixel. This time reduction is particularly beneficial for high-resolution displays with many pixels, as the cumulative programming time across all pixels is significantly reduced. The well-defined voltage levels enable faster charging of pixel capacitances, directly addressing the time penalty associated with high pixel counts.
Data Source
AI summary
The invention relates to an active matrix display device (6) comprising a display panel (2) with a matrix of display pixels (3), and row and column electrodes (11,12) coupled to the display pixels (3). Each of the display pixels (3) has a current mirror circuit adapted to receive a programming current (Iprog) via the column electrodes (11) and to reproduce the programming current (Iprog) for driving an emissive element (14). The display device (6) is further arranged to execute a calibration phase wherein a calibration voltage (Vcal) is applied at each column electrode (11) before the programming current (Iprog) is applied.