Eccentric Dosing Disc Monolayer Spacers for LCD Uniformity
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Solution Overview
Problem
Existing apparatuses fail to achieve a uniform distribution of spacers for liquid crystal devices, leading to visible optical defects due to high standard deviation in spacer density and clusters, and require excessive time to deliver spacers to large window substrates.
Innovation Solution
A dosing device comprising a reservoir, a rotatable dosing disc, and a suction device with a dosing opening and suction opening arranged eccentric to the rotational axis, ensuring a monolayer of granular material is delivered and sucked into the suction device, mixed with a gas stream, to achieve a uniform distribution of spacers with low standard deviation and reduced clustering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If known apparatuses are used to distribute spacers, then spacers can be delivered to the substrate, but the distribution is non-uniform with high standard deviation and clusters, causing optical defects
Solution Approach 1:
A dosing disc with a dosing gap acts as an intermediary between the reservoir and the substrate. The dosing gap controls the flow of granular material, ensuring that spacers are delivered one at a time in a monolayer, which prevents clustering and achieves uniform distribution on the substrate.
Solution Approach 2:
The dosing disc divides the continuous flow of granular material into discrete individual spacer deliveries. By rotating the dosing disc with a controlled speed, each spacer is separated and delivered individually to the substrate, ensuring uniform spacing and preventing clusters.
2Productivity
If known apparatuses are used to distribute spacers, then spacers can be delivered to the substrate, but the time required to deliver spacers for large window substrates is excessive
Solution Approach 1:
The dosing disc rotates continuously, allowing for uninterrupted delivery of spacers to the substrate. This continuous rotation enables high-speed coating of large window substrates without stopping, significantly reducing the total coating time compared to batch processing methods.
Solution Approach 2:
A suction device uses gas flow to rapidly transport spacers from the dosing disc to the substrate. The pneumatic system enables fast delivery of spacers across large areas, improving productivity and reducing the tact time for coating large window substrates.
3Manufacturing precision
If a monolayer of spacers is delivered, then uniform distribution is achieved, but precise control of the dosing gap is required to prevent clusters
Solution Approach 1:
The dosing gap distance is optimized to be between 0.5 mm and 2 mm, which is the critical parameter range for achieving monolayer formation. By controlling this specific parameter within the defined range, the system ensures that spacers are delivered one at a time without requiring complex control mechanisms.
Solution Approach 2:
The dosing disc rotates dynamically, and the suction device operates simultaneously to create a balanced flow system. This dynamic operation allows the granular material to flow smoothly through the dosing gap in a controlled manner, maintaining monolayer formation without requiring static precision adjustments.
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 proposed solution significantly reduces the time required to deliver spacers and achieves a uniform distribution with low standard deviation, preventing visible optical defects by ensuring a monolayer transport and using a Venturi nozzle for efficient particle suction.
Implementation Method 1
The monolayer of particles is being sucked into the suction device and mixed with a gas stream, preferably a constant gas stream, when the particles are being transported to the suction device by rotation of the dosing disc
Data Source
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AI summary
The invention relates to a dosing device (10) for dosing a granular material (16) comprising a reservoir (12) for storing the granular material (16), a dosing disc (20), anda suction device (24). The dosing disc (20) is rotata- ble around a rotational axis (22). The reservoir (12) has a dosing opening (14) facing the dosing disc (20) and the dosing opening (14) is arranged above the dosing disc (20) such that a dosing gap is formed between a surface of the dosing disc (20) and a surface (26) surrounding the dosing opening (14).The dosing opening (14) isarranged eccentric with respect to the rotational axis (22). The suction device (24) has an opening (25) facing the dosing disc(20), the opening (25) being arranged above the dosing disc (20) and likewise being arranged eccentric with respect to the rotational axis (22). The size of the dosing gap ischosen such that a mon- olayer (18) of the particles (17) of the granular material (16) is dosed from the reservoir (12) through the dosing opening (14) onto the surface of the dosing disc (20). The suction device (24) isconstructed and arranged such that the monolayer (18) of particles (17) is being sucked into the suc- tion device (24) and mixed with a gas stream when the particles (17) are being transported to the suction device (24) by rotation of the dosing disc (20). Further aspects of the invention relate to a spraying device comprising such a dosing device and a method for applying a granular material to a substrate.