Offset Photomask Boundaries for LCD Streak Reduction
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Solution Overview
Problem
Streak-shaped display irregularities occur in high-definition liquid crystal display apparatuses when using photoalignment treatment, leading to decreased display quality, particularly in VA mode liquid crystal display apparatuses with small pixel sizes.
Innovation Solution
A manufacturing method for liquid crystal display apparatuses involves using a photomask with light-transmitting and light-blocking portions arranged in a specific pattern, where the boundary between these portions is offset from the domain boundary during exposure, to prevent or reduce streak irregularities by ensuring uniform exposure across the photoalignment film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photoalignment treatment is performed using conventional photomasks, then alignment regions are defined, but streak-shaped display irregularities occur in high-definition liquid crystal display apparatuses
Solution Approach 1:
The patent applies local quality by making the light-transmitting portions have different widths in different regions of the photomask. Specifically, the width of light-transmitting portions is adjusted locally to compensate for exposure amount variations across the substrate, ensuring uniform exposure and preventing streak irregularities while maintaining precise alignment region definition.
2Manufacturing precision
If small pixel sizes are used for high definition, then display quality improves, but streak irregularities become more prominent
Solution Approach 1:
The patent changes the physical parameter of photomask structure by varying the width of light-transmitting portions. This parameter modification compensates for the increased sensitivity to exposure non-uniformity that occurs with smaller pixel sizes, thereby maintaining high display definition while eliminating streak irregularities.
3Area of stationary object
If photomask size is increased to match substrate size, then coverage improves, but manufacturing cost increases
Solution Approach 1:
The patent segments the photomask into multiple smaller photomasks that can be arranged in an array. This segmentation allows the use of smaller, more cost-effective photomasks while still covering the entire substrate area through the array configuration, thereby reducing manufacturing cost while maintaining full coverage.
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
The method effectively prevents or reduces streak-shaped display irregularities, enhancing the display quality of VA mode liquid crystal display apparatuses by ensuring consistent alignment and orientation of liquid crystal domains, thereby improving viewing angle characteristics.
Implementation Method 1
a photoalignment treatment is performed using a photomask and an exposure device
Implementation Method 2
a plurality of pairs of a light-transmitting portion TR that transmits exposure light for exposing a region of the first photoalignment film 12 which is to serve as the first alignment region 12a, and a light-blocking portion SR that blocks light toward a region of the first photoalignment film 12 which is to serve as the second alignment region 12b
Data Source
AI summary
A manufacturing method for a liquid crystal display apparatus according to an embodiment of the present invention includes a step (A) of preparing a first substrate including a pixel electrode and a first photoalignment film that has not been subjected to an alignment treatment, and a step (B) of exposing a region of the first photoalignment film which is to serve as a first alignment region through a plurality of first photomasks, while transporting the prepared first substrate in a predetermined transport direction, the plurality of first photomasks including two or more first photomasks arranged in a second direction intersecting the transport direction. Each first photomask includes a plurality of pairs of a light-transmitting portion and a light-blocking portion. Each first photomask is designed so that in the step (B), on a side closer to one end of the first photomask, a boundary between the light-transmitting portion and the light-blocking portion is offset from a domain boundary toward the one end, and on a side closer to the other end of the first photomask, the boundary between the light-transmitting portion and the light-blocking portion is offset from the domain boundary toward the other end.