Display Unit Transistor Layout for Light Leakage Reduction
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Solution Overview
Problem
Organic EL display units face challenges with long-term reliability due to light leakage, which affects the performance and lifespan of transistors, particularly when blue light enters the channel of adjacent pixels, causing shifts in threshold voltage and reduced reliability of TFTs.
Innovation Solution
The display unit is designed with a configuration where transistors corresponding to adjacent organic EL devices are positioned farther away from the retentive capacity, reducing the amount of light leakage and thereby minimizing the impact on transistor reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If transistors are positioned closer to the organic EL device for compact layout, then device area is reduced, but light leakage into transistors increases causing threshold voltage shifts and reduced reliability
Solution Approach 1:
An insulating film is introduced as an intermediary layer between the organic EL device and the transistor. This insulating film acts as a barrier that blocks light leakage from the organic EL device from reaching the transistor channel, thereby preventing threshold voltage shifts while allowing the transistor to be positioned closer to the organic EL device for compact layout.
Solution Approach 2:
The insulating film is selectively positioned only in the region between the organic EL device and the transistor channel, providing localized protection against light leakage. This allows other regions to maintain close spacing for compactness while the critical region near the transistor channel receives enhanced light blocking protection.
2Reliability
If transistors are positioned farther from the organic EL device to reduce light leakage, then transistor reliability is improved, but device area increases
Solution Approach 1:
The insulating film serves as a light-blocking intermediary that enables the transistor to be positioned closer to the organic EL device without suffering from light leakage effects. This eliminates the need to increase device area for spacing purposes, as the insulating film provides the necessary protection in the compact configuration.
3Illumination intensity
If blue light enters the transistor channel, then light leakage is observed, but this causes threshold voltage shifts and reduced long-term reliability
Solution Approach 1:
The insulating film acts as a light-blocking intermediary positioned between the organic EL device and the transistor channel. It specifically blocks blue light leakage from reaching the transistor channel, thereby preventing threshold voltage shifts and maintaining long-term transistor reliability while allowing the display to operate normally.
Data Source
AI summary
A display unit with which lowering of long-term reliability of a transistor is decreased is provided. The display unit includes a display section having a plurality of organic EL devices with light emitting color different from each other and a plurality of pixel circuits that are singly provided for every said organic EL device for every pixel. The pixel circuit has a first transistor for writing a video signal, a second transistor for driving the organic EL device based on the video signal written by the first transistor, and a retentive capacity, and out of the first transistor and the second transistor, a third transistor provided correspondingly to a second organic EL device adjacent to a first organic EL device is arranged farther from the first organic EL device than a first retentive capacity provided correspondingly to the second organic EL device out of the retentive capacity.