Display Substrate Dual-Gate TFT Layout for Light Uniformity
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Solution Overview
Problem
Existing display panels suffer from poor uniformity of light emission due to process instability, parameter drift, and device aging in OLED and TFT light-emitting devices.
Innovation Solution
A display substrate with a pixel drive circuit that includes a drive transistor with a double-gate TFT structure, and a photosensitive circuit to sense light emission and perform optical compensation, improving light uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional single-gate TFT structure is used for the drive transistor, then the device complexity is low and manufacturing is easier, but the output characteristics are insufficient and light emission uniformity is poor
Solution Approach 1:
The drive transistor is divided into two independent gate electrodes (first gate electrode and second gate electrode) that can be controlled separately. This segmentation allows independent optimization of threshold voltage and drive current, improving light emission uniformity without requiring a complete redesign of the transistor structure
Solution Approach 2:
The dual-gate TFT structure serves multiple functions: the first gate electrode controls the threshold voltage to prevent threshold voltage shift, while the second gate electrode controls the drive current to maintain current stability. This multi-functionality addresses both process instability and device aging issues simultaneously
2Manufacturing precision
If no optical compensation mechanism is implemented, then the device complexity is low, but process instability and parameter drift lead to poor light emission uniformity
Solution Approach 1:
An optical compensation circuit is introduced that senses the actual light output and feeds back this information to adjust the drive current. This feedback mechanism compensates for process variations and device aging, maintaining consistent light emission uniformity across different manufacturing batches and over time
Solution Approach 2:
The dual-gate TFT structure is designed with predetermined gate control configurations that preemptively compensate for expected process variations and aging effects. By pre-configuring the gate electrodes to counteract anticipated drift, the system maintains uniformity without requiring complex real-time adjustment mechanisms
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enhances the output characteristics of the drive transistor and improves light uniformity across the display panel, addressing issues of process instability and device aging.
Implementation Method 1
the first conductive film layer at least includes a first light shielding portion, the first light shielding portion is located between the substrate and the drive active layer
Implementation Method 2
a photosensitive circuit disposed on the substrate, wherein the photosensitive circuit is configured to sense light emitted by at least one of the pixel units
Data Source
AI summary
The display substrate includes: a substrate; a plurality of pixel units on the substrate, each pixel unit includes a plurality of sub-pixels, each sub-pixel includes a light-emitting element and a pixel drive circuit; a photosensitive circuit on the substrate; a first conductive film layer on the substrate. The pixel drive circuit includes a drive transistor, a gate electrode of the drive transistor is located on a side of a drive active layer away from the substrate, an orthographic projection of the gate electrode of the drive transistor on the substrate at least partially overlaps an orthographic projection of the drive active layer on the substrate. The first conductive film layer includes a first light-shielding portion between the substrate and the drive active layer, and an orthographic projection of the first light-shielding portion on the substrate at least partially overlaps the orthographic projection of the drive active layer on the substrate.