Light-emitting device

A light-emitting device with a normally-on transistor and a second gate electrode system addresses brightness unevenness by accurately measuring and correcting threshold voltage variations, ensuring consistent pixel luminance.

JP7727807B2Active Publication Date: 2025-08-21SEMICON ENERGY LAB CO LTD
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Patent Information

Application Number
JP2024128962
Authority / Receiving Office
JP · JP
Patent Type
Patents
Current Assignee / Owner
Priority Date
2011-09-14
Filing Date
2024-08-05
Publication Date
2025-08-21
Estimated Expiration
2032-09-10

AI Technical Summary

Technical Problem

Existing light-emitting devices suffer from brightness unevenness due to variations in threshold voltage of transistors, which cannot be accurately measured when the gate and drain electrodes are short-circuited, leading to incorrect determination of the threshold voltage.

Method used

A light-emitting device using a normally-on transistor with a second gate electrode and a switch to control the connection between the gate and drain terminals, allowing for accurate threshold voltage measurement and correction, even in a normally-on state.

Benefits of technology

The solution effectively reduces luminance variations between pixels by accurately determining and correcting threshold voltage, resulting in high-quality image display.

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Abstract

To provide a light-emitting device in which the variation in luminance among pixels owing to the variation in threshold voltage can be reduced even when a transistor is normally on.SOLUTION: In a light-emitting device, the supply of current to a light-emitting element is controlled by use of a transistor having a normal gate electrode (first gate electrode) and a second gate electrode for controlling a threshold voltage. Further, the light-emitting device has one or more switches for selecting conduction or non-conduction between the first gate electrode of the transistor and a drain terminal. When the threshold voltage of the transistor is acquired, the first gate electrode of the transistor and the drain terminal are brought into conduction with the switch, and the threshold voltage of the transistor is shifted by controlling the potential of the second gate electrode.SELECTED DRAWING: Figure 1
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Citation Information

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