Display Substrate Transistor Channel Overlap for Light Shielding
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Solution Overview
Problem
Current display technologies face challenges in maintaining high light transmittance in functional device settings while ensuring accurate data signal writing and reducing threshold voltage shifts in OLED display panels, particularly due to the lack of effective light shielding for transistors in pixel circuits.
Innovation Solution
The display substrate design includes a functional device setting region with a higher light transmittance than the main display region, featuring a specific arrangement of pixel circuits and light-emitting devices where the channel regions of transistors are partially overlapped with the electrodes of light-emitting devices to prevent external light from reaching the transistors, and the use of transparent conductive layers and signal lines to enhance light transmittance and reduce electromagnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the functional device setting region uses transparent conductive layers and signal lines to enhance light transmittance, then the light transmittance is improved, but external light may reach the transistors causing threshold voltage shifts
Solution Approach 1:
The patent applies different properties to different regions: the functional device setting region uses transparent conductive layers and transparent signal lines for high light transmittance, while the main display region uses conventional opaque conductive layers. This local differentiation allows each region to be optimized for its specific function without compromising the other.
Solution Approach 2:
The patent introduces a light-shielding layer as an intermediary element between the transparent conductive layer and the transistor channel region. This light-shielding layer selectively blocks external light from reaching the transistor channel while allowing the transparent conductive layer to maintain high light transmittance for the functional device above it.
2Object-generated harmful factors
If transparent signal lines are used in the functional device setting region, then electromagnetic interference is reduced, but the ability to shield transistor channel regions from external light is compromised
Solution Approach 1:
The patent segments the signal line into two parts: a transparent signal line portion in the functional device setting region that reduces electromagnetic interference, and an opaque light-shielding portion that blocks external light from reaching the transistor channel. This segmentation allows each portion to address its specific harmful factor independently.
Solution Approach 2:
The signal line is designed with multi-functionality: it serves both as an electrical connection (signal transmission) and as a light-shielding element. The transparent signal line portion provides electrical connection with reduced electromagnetic interference, while the integrated light-shielding portion provides optical protection, combining multiple functions into a single structure.
3Object-affected harmful factors
If the channel region of the first transistor is overlapped with the first electrode of the light-emitting device, then external light is blocked from reaching the transistor, but the light transmittance of the functional device setting region is reduced
Solution Approach 1:
The patent introduces a light-shielding layer as an intermediary between the transparent conductive layer and the transistor channel region. This light-shielding layer blocks external light from reaching the transistor channel while allowing the transparent conductive layer to maintain high light transmittance for the functional device, thus resolving the contradiction between light blocking and light transmittance.
Solution Approach 2:
The patent resolves the spatial conflict by adding a vertical dimension solution. Instead of horizontally positioning the channel region under the electrode (which would block light), the patent uses a light-shielding layer in the vertical stack to block light while maintaining the horizontal overlap configuration for electrical connection purposes.
Data Source
AI summary
A display substrate includes a substrate, scan signal lines, a plurality of first pixel circuits and a plurality of first light-emitting devices. The plurality of first pixel circuits are disposed on the substrate, and are located in a functional device setting region. At least one first pixel circuit includes a first transistor. At least one first light-emitting device includes a first electrode. The at least one first light-emitting device includes at least one first color light-emitting device, and the at least one first pixel circuit includes at least one first color pixel circuit, and a first color pixel circuit is electrically connected to a first color light-emitting device. An orthographic projection of a channel region of a first transistor in the first color pixel circuit on the substrate is at least partially overlapped with an orthographic projection of a first electrode of the first color light-emitting device on the substrate.