OLED Pixel Control Lines for Staggered Measurement and Programming
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Solution Overview
Problem
OLED pixel cells in luminous displays experience performance degradation and manufacturing imperfections, leading to varying electro-optical properties across the screen, which existing methods fail to address effectively during normal operation without increasing the number of control lines, thus affecting light emission efficiency.
Innovation Solution
A method where control lines for one row of pixel cells control adjacent rows, allowing for simultaneous programming and measurement of current and voltage in a staggered manner, reducing the number of control lines required and enabling continuous measurement during normal operation by reusing existing lines for both tasks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional control lines are added for measuring pixel cell properties during normal operation, then measurement capability is improved, but device complexity and effective light emission area are worsened
Solution Approach 1:
The patent makes existing control lines serve dual functions: during measurement cycles, they measure pixel cell properties; during normal operation cycles, they control pixel cell switching. This multi-functionality eliminates the need for separate dedicated measurement lines, reducing device complexity while maintaining measurement capability.
Solution Approach 2:
The patent implements periodic measurement cycles interspersed with normal operation cycles. During specific time periods, the control lines are reconfigured to perform measurements; during other periods, they resume normal control functions. This time-division multiplexing allows measurement without permanent additional hardware.
2Measurement precision
If additional control lines are added for measuring pixel cell properties, then measurement capability is improved, but the effective area for light emission is reduced
Solution Approach 1:
By making existing control lines multi-functional (serving both control and measurement purposes), the patent eliminates the need for additional physical lines that would occupy space and reduce the effective light emission area of the display.
Solution Approach 2:
The patent merges the measurement function with the existing control line infrastructure, combining two functions (control and measurement) into a single set of lines, thereby avoiding additional space requirements and preserving maximum light emission area.
3Device complexity
If measurement is performed during normal operation using the same lines, then the number of control lines is reduced, but permanent adaptation of driving signals is not enabled
Solution Approach 1:
The patent implements periodic measurement cycles during normal operation, allowing continuous monitoring of pixel cell properties. The measured data is used to progressively adapt driving signals over time, enabling permanent adaptation while using the same control lines for both measurement and control functions.
Solution Approach 2:
The patent establishes a feedback loop where pixel cell properties are measured during operation, and the measured values are used to adapt and optimize driving signals. This continuous feedback enables permanent signal adaptation without requiring additional control lines, improving display reliability and performance over time.
Data Source
AI summary
A luminous display includes pixels arranged in rows and columns. Control signals that are used for controlling first switches for measuring parameters of pixel cells in a first row are also used to control second switches for programming pixel cells in a second row. In this way it is possible to use a single control signal for selecting one pixel cell for programming and simultaneously selecting another pixel cell for measuring. Programming and measuring are thus performed in a time staggered manner, while the addressing is moved to the respective next row. The programming is preferably voltage programming. In one embodiment the current through the pixel cell that is currently programmed is interrupted. In another embodiment the measuring is performed only after the transient current into signal holding means coupled to current control means has set.