Electrophoretic Display Single-Mask Fabrication
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Solution Overview
Problem
The existing electrophoretic display devices require a complex and costly fabrication process involving multiple masks, which increases production time and can lead to issues like incomplete liquid crystal filling and degraded picture quality when applied to liquid crystal display (LCD) devices due to steps in the passivation layer.
Innovation Solution
The electrophoretic display device and its fabrication method minimize the number of masks used by forming the organic semiconductor layer, gate insulating layer, and gate electrode through a single masking process, eliminating the need for an open area in the passivation layer and allowing for smoother alignment of the liquid crystal layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple masks are used in the fabrication process to form source/drain electrodes, pixel electrodes, organic semiconductor layers, gate insulating layers, and gate electrodes separately, then each layer can be precisely formed, but the fabrication process becomes complex and time-consuming
Solution Approach 1:
The patent combines multiple separate masking processes into a single integrated masking process. Specifically, the source/drain electrode pattern, pixel electrode pattern, organic semiconductor layer pattern, gate insulating layer pattern, and gate electrode pattern are all formed through one masking operation using a multi-layer resist structure, rather than requiring separate masks for each layer. This merging of processes maintains manufacturing precision while dramatically improving fabrication productivity.
Solution Approach 2:
The single mask used in the invention serves multiple functions simultaneously. It defines patterns for the source/drain electrodes, pixel electrodes, organic semiconductor layers, gate insulating layers, and gate electrodes all in one operation. This multi-functional mask replaces what would traditionally require five or more separate masks, reducing process complexity while maintaining the precision needed for each specific layer formation.
2Reliability
If an open area is formed in the passivation layer to prevent pixel voltage from weakening, then the electrophoretic film can be properly driven, but the passivation layer creates steps that cause incomplete liquid crystal filling and degraded picture quality
Solution Approach 1:
The invention extracts or removes the problematic open area structure from the passivation layer. Instead of creating openings in the passivation layer to expose pixel electrodes, the patent forms the pixel electrodes to extend through and contact the electrophoretic film directly, eliminating the need for open areas in the passivation layer. This extraction of the problematic feature resolves the contradiction by maintaining reliable electrophoretic film driving while eliminating the steps that caused incomplete liquid crystal filling.
Solution Approach 2:
The patent inverts the traditional approach by having the pixel electrodes extend outward to contact the electrophoretic film directly, rather than having open areas in the passivation layer expose the pixel electrodes. This inversion of the structural arrangement eliminates the need for open areas while maintaining the necessary electrical contact, thereby solving the picture quality issue caused by passivation layer steps.
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 approach reduces fabrication costs and time, ensures complete liquid crystal filling, and improves picture quality by minimizing steps in the protection layer, enabling efficient production and application to LCD devices.
Implementation Method 1
an electrophoretic display device is an image displayer using a phenomenon that when a pair of electrodes receiving voltage are put in a colloid solution, colloid particles are moved to one polarity
Data Source
AI summary
An electrophoretic display device includes: a first substrate having a plurality of pixels formed in a plurality of vertical pixel rows and a plurality of horizontal pixel rows; a plurality of data lines formed at every vertical pixel row of the first substrate; a thin film transistor (TFT) formed at each pixel of the first substrate and including a source electrode, a drain electrode, an organic semiconductor layer, and a gate electrode; a passivation layer formed on the TFTs and the data lines of the first substrate and including a first contact hole exposing the drain electrode of the TFT and a second contact hole exposing the gate electrode of the TFT; a pixel electrode formed on the passivation layer at each pixel of the first substrate and connected with the drain electrode of the TFT via the first contact hole of the passivation layer; a plurality of gate lines formed on the passivation layer at every horizontal pixel row of the first substrate and connected with the gate electrode of the TFT via the second contact hole of the passivation layer; a second substrate attached to the first substrate in a facing manner; a common electrode formed on the second substrate; and an electrophoretic film formed between the first and second substrates.