Capacitance Element Stabilizes Drive Circuit Voltage
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Solution Overview
Problem
In electro-optical devices, the miniaturization and high-definition requirements lead to increased capacitance area needs, making it difficult to secure sufficient capacity for data line capacitance, especially with thicker insulating films in trench or layered capacitance structures, which affects the reliability of scanning line drive circuits.
Innovation Solution
The electro-optical device incorporates a capacitance element with one end coupled to a drain node and the other end held at a predetermined potential, using a capacitance configuration where the third interlayer insulating film is sandwiched between a peripheral electrode and wiring, which reduces parasitic capacitance and enhances capacity without relying on the storage capacitor structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a trench structure or thicker insulating film is used for storage capacitance, then the capacitance area is increased, but the insulating film thickness increases making it difficult to secure sufficient capacity
Solution Approach 1:
The patent transitions from vertical capacitance formation (through thicker insulating films in trench structures) to horizontal capacitance formation by extending the capacitance electrode in the planar direction. This allows increased capacitance area without increasing insulating film thickness, resolving the contradiction between capacitance area and film thickness requirements
Solution Approach 2:
The patent merges the capacitance electrode with existing electrode structures in the drive circuit, specifically utilizing the gate electrode or source/drain electrode as part of the capacitance structure. This integration allows capacitance formation without requiring separate thick insulating film layers, thereby maintaining thin film profiles while achieving sufficient capacitance area
2Productivity
If miniaturization and high definition are pursued, then device density is improved, but sufficient capacitance capacity becomes difficult to secure due to space constraints
Solution Approach 1:
The patent extends the capacitance electrode in the horizontal planar dimension rather than relying on vertical depth (trench structures). This dimensional shift allows capacitance area to increase laterally without consuming vertical space, thereby maintaining high device density while securing sufficient capacitance capacity in miniaturized displays
Solution Approach 2:
The patent designs the capacitance electrode to serve multiple functions: it provides capacitance storage while also acting as a signal transmission conductor within the drive circuit. This multi-functionality reduces the need for separate dedicated capacitance structures, saving space and maintaining high device density while ensuring adequate capacitance capacity
3Device complexity
If conventional capacitance structures are used in drive circuits, then circuit integration is simplified, but voltage instability and malfunctions occur at critical nodes
Solution Approach 1:
The patent introduces a capacitance electrode as an intermediary element between critical nodes in the drive circuit (such as between gate electrode and source/drain electrode). This intermediary capacitance structure stabilizes voltage fluctuations at critical nodes without adding complex circuit logic, thereby improving reliability while maintaining circuit integration simplicity
Solution Approach 2:
The capacitance electrode is positioned and configured in advance during the TFT manufacturing process to preemptively stabilize voltage at critical nodes before signal transmission occurs. This preliminary capacitance provisioning prevents voltage instability and malfunctions from occurring during circuit operation, enhancing reliability without complicating the integrated circuit design
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
This configuration stabilizes the voltage at critical nodes, reduces power consumption, and prevents malfunctions in the scanning line drive circuit, ensuring reliable operation and improved capacitance performance even with thinner insulating films.
Implementation Method 1
a capacitance element having one end coupled to the drain node and another end held at a predetermined potential. The capacitance element includes a first peripheral electrode formed of a same layer as the plurality of pixel electrodes, a wiring formed of a predetermined electrode layer, and an interlayer insulating film sandwiched between the first peripheral electrode and the wiring
Data Source
AI summary
Provided is an electro-optical device including a plurality of pixel electrodes arranged in a display region, a first transistor that captures a pulse supplied to a source node by using a clock signal supplied to a gate node and outputs the pulse from the drain node, a second transistor to which the pulse output from the drain node is input, and a capacitance element having one end coupled to the drain node and another end held at a predetermined potential. In the capacitance element, an interlayer insulating film is sandwiched between a first peripheral electrode formed of a same layer as the plurality of pixel electrodes and a wiring formed of a predetermined electrode layer, and the wiring includes a portion overlapping the second transistor in plan view.