Display Pixel Circuit Layout Using Silicon and Oxide TFTs
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Solution Overview
Problem
Display devices face challenges in achieving high integration density, low power consumption, and reduced process time and cost due to the increasing number of thin film transistors required for accurate luminescence control, which existing technologies have not adequately addressed.
Innovation Solution
A display apparatus is designed with a combination of a silicon semiconductor-based thin film transistor and an oxide semiconductor-based thin film transistor, along with a storage capacitor, where the second semiconductor layer and one of the electrodes of the storage capacitor are arranged on the same layer, and a second gate insulating layer is placed between the first gate electrode and the second semiconductor layer, optimizing the layout for reduced process complexity and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of thin film transistors is increased to accurately control luminescence intensities, then display quality and resolution are improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent combines the storage capacitor and second thin film transistor onto the same substrate layer, merging two separate components into a single integrated unit. This reduces the total number of discrete components while maintaining the functionality of both the storage capacitor for voltage retention and the thin film transistor for signal control, thereby improving luminescence intensity precision without proportionally increasing device complexity
Solution Approach 2:
The second thin film transistor serves multiple functions: it acts as a switching element for controlling data signal input to the storage capacitor, and simultaneously functions as part of the pixel circuit for driving the light-emitting element. This multi-functionality reduces the overall transistor count needed while maintaining accurate luminescence control capability
2Measurement precision
If the number of thin film transistors is increased for better display control, then resolution and image quality improve, but process time and manufacturing cost increase
Solution Approach 1:
By merging the storage capacitor and second thin film transistor into a single fabricated unit on the same substrate, the patent reduces the number of separate fabrication steps required. The integrated structure allows simultaneous formation of both components in fewer process cycles, thereby reducing overall manufacturing process time while maintaining the precision needed for display control
Solution Approach 2:
The storage capacitor is formed in advance during the thin film transistor fabrication process, with its electrodes and dielectric layers created as part of the transistor structure. This preliminary formation of the storage capacitor before final pixel assembly reduces subsequent processing steps and overall manufacturing time
3Measurement precision
If more thin film transistors are used for accurate luminescence control, then display quality improves, but power consumption increases
Solution Approach 1:
The storage capacitor is pre-charged to the required voltage level during the programming phase before the light-emitting element needs to maintain its luminance. This preliminary charging action allows the capacitor to retain the voltage without requiring continuous active current flow from the thin film transistor, thereby reducing ongoing power consumption while maintaining precise luminescence control
Solution Approach 2:
The storage capacitor serves itself by retaining the voltage charge without requiring continuous external power supply or active control from the thin film transistor. Once charged, the capacitor autonomously maintains the voltage level needed for stable light-emitting element operation, reducing the power consumption burden on the transistor and overall pixel circuit
Data Source
AI summary
A display apparatus includes a substrate including a display area; a first thin film transistor arranged on the display area of the substrate and having a first semiconductor layer including a silicon semiconductor and a first gate electrode insulated from the first semiconductor layer by a first gate insulating layer; a second thin film transistor arranged on the display area of the substrate and having a second semiconductor layer including an oxide semiconductor and a second gate electrode insulated from the second semiconductor layer; and a storage capacitor at least partially overlapping the first thin film transistor and having a lower electrode and an upper electrode, wherein the second semiconductor layer and one of the lower electrode and the upper electrode are arranged on a same layer.