Enamelled Steel Projection Board Surface Roughness
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Solution Overview
Problem
Visual communication boards face challenges in being both writable and dry-wipeable while minimizing light reflections, as smooth enamelled coatings are suitable for writing but cause reflections, and matte coatings for projection reduce dry-wipeability.
Innovation Solution
A double-sided enamelled steel board with a specific roughness profile achieved through a two-layer enamel undercoat and a thin finishing coat composed of enamel powder and screen-printing medium, which scatters light and maintains dry-wipeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a smooth enamelled coating is applied to the board, then the board becomes properly writable with felt-tip pens, but light reflections are strengthened and readability is reduced
Solution Approach 1:
The patent applies different surface qualities to different functional zones of the board. The writing surface maintains a smoother local texture for optimal felt-tip pen performance, while the projection surface incorporates a controlled roughness profile (Ra = 0.6-1.2 μm) to diffuse projector light and reduce reflections. This spatial differentiation of surface properties allows both writing and projection functions to coexist without compromising either.
2Object-affected harmful factors
If a matt enamelled coating is applied to reduce light reflections, then the board becomes suitable for projection, but dry-wipeability deteriorates
Solution Approach 1:
The patent precisely controls the roughness parameters of the enamel coating to achieve optimal performance. By specifying Ra = 0.6-1.2 μm and Rz = 3.0-8.0 μm, the invention finds the optimal parameter range that provides sufficient light diffusion for projection while maintaining enough surface smoothness for dry-wipeability. This quantitative parameter optimization resolves the contradiction between matt appearance and wipeability.
3Object-affected harmful factors
If the surface roughness is increased to diffuse incident light for projection, then light reflections are reduced, but the smoothness required for dry-wipeability is compromised
Solution Approach 1:
The patent creates a differentiated surface structure where the overall surface has a controlled roughness profile for light diffusion, while the local micro-structure maintains sufficient smoothness for wiping. The enamel coating's granular structure at the microscopic level provides light scattering, yet the macroscopic surface remains smooth enough for dry-wipeability, effectively decoupling these two requirements through multi-scale surface engineering.
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 solution provides a board that is both readable and free from light reflections, suitable for writing and projection, with excellent dry-wipeability and antireflection properties.
Implementation Method 1
a third thin finishing coat is applied consisting of approximately two thirds enamel powder and one third screen-printing medium... which after annealing at a temperature of more than 600° C. presents the following roughness profile... and such that this third thin finishing coat obtains an optical roughness such that the incident light is scattered and disruptive light reflections are avoided
Implementation Method 2
which after annealing at a temperature above 800° C.... and which after annealing at a temperature of more than 600° C.
Data Source
AI summary
Disclosed is a projection and communication board, having a double-sided enamelled steel plate with an enamel undercoat, on which a second white enamel coat is laid on the writing side, which after annealing presents a roughness defined by Ra =0.6-1.2 μm, Rz =3.0-8.0 μm, and R3z =3.0-8.0 μm. On this a third thin finishing coat is applied consisting of enamel powder, more than 90% of which consists of grains of less than 15 μm, and which after annealing presents a roughness defined by Ra =0.4-1.4 μm, Rz =2.0-6.0 μm, and R3z =2.0-6.0 μm.