Organic EL Display Row Drive Circuit for Threshold Compensation
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Solution Overview
Problem
Existing organic EL display technologies face challenges in reducing the number of wiring lines while maintaining efficient threshold voltage compensation and preventing luminance non-uniformity, particularly due to increased circuit size and power consumption, as well as insufficient threshold value detection periods.
Innovation Solution
The implementation of an active matrix-type display device with a row drive circuit that collectively activates scanning and control lines for each row group during initialization and threshold value detection periods, and selectively activates them in reverse order every frame period, along with a power control circuit that provides a common power line for initialization, reducing the number of output buffers and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the constant-voltage type control method is adopted to reduce the number of wiring lines, then the aperture ratio is improved, but threshold voltage compensation becomes complex and requires more control lines
Solution Approach 1:
The patent combines the threshold voltage compensation function with the existing constant-voltage control circuit by adding a compensation transistor that operates during a specific period. This merges two functions (compensation and voltage control) into a unified circuit structure, avoiding the need for separate compensation circuitry and additional control lines.
Solution Approach 2:
The patent performs threshold voltage compensation in advance during a dedicated compensation period before the normal display operation. By preliminarily adjusting the threshold voltage of the driving transistor, the circuit ensures accurate current control without requiring continuous complex compensation mechanisms during operation.
2Manufacturing precision
If threshold voltage compensation is implemented in conventional pixel circuits, then luminance uniformity is improved, but the number of wiring lines and circuit size increase
Solution Approach 1:
The compensation transistor serves multiple functions: it acts as a switch for threshold voltage compensation during the compensation period, and as part of the normal current control path during display operation. This multi-functionality eliminates the need for separate compensation circuitry, reducing overall circuit size while maintaining luminance uniformity.
Solution Approach 2:
The patent implements threshold voltage compensation periodically during a specific compensation period within each frame cycle. This time-division approach allows the same circuit components to serve both compensation and display functions at different times, avoiding the need for continuously active compensation circuitry.
3Use of energy by moving object
If the number of output buffers in the power control circuit is reduced, then power consumption is lowered, but the ability to provide initialization potential to all rows simultaneously is compromised
Solution Approach 1:
The patent divides the display panel rows into multiple row groups, with each group assigned to a separate output buffer. This segmentation allows the power control circuit to manage initialization potentials for multiple rows simultaneously using fewer output buffers, reducing power consumption while maintaining reliable initialization through parallel operation of multiple groups.
Data Source
AI summary
Provided is a display device that can sufficiently secure a period for threshold value detection with a simple configuration and that can inhibit occurrence of luminance non-uniformity. The display device includes a plurality of pixel circuits; a gate driver circuit connected to a plurality of scanning signal lines and a plurality of control lines; and a power control circuit connected to a plurality of power lines through a common power line. Each pixel circuit includes an organic EL element, a plurality of TFTs, and a capacitor. During each frame period, after initialization and threshold value detection are collectively performed on a plurality of rows, writing and light emission are performed sequentially on a row-by-row basis. Here, in a preceding frame (first frame) of two consecutive frame periods, writing is performed in order from the first row to the nth row (ascending order). In a subsequent frame (second frame) of the two frame periods, writing is performed in order from the nth row to the first row (descending order).