Full Color Mechanical Display

You might be familiar with flip-disk display (The top yellow bus number in the picture) as you probably have seen it in many places, though you might not be familiar with the technology name, how it works and what it is made of.

Source: Wikimedia

Flip disk display consists of flat plates with a different color on every side. The disk is flipped using a magnetic actuator so that the color switches. The display cells are placed in a grid and used to write information or make simple drawings. As shown below the same display cell switches from white color to black color by flipping the center disk.

Source: wikiwand.com

The result of such an assembly of simple systems combined with a proper control system can be a bicolor active display system. The best example is demonstrated in the video below.

Now that you are familiar with the technology, I think the limitations are noticable and one major limitation is color variety. The regular system design only allows a bycolor display.The suggested design described in this article allows a grey scale dispay mode or even an CMYK display + Greyscale that makes possible the display of a full color photo.There is a catch though, the picture display is better when the mechanical pixels are smaller just like any pixel based system. So lets go in details of how four colors pixel can be made and then move to the greyscale additional layer.

If we replace a disk that has two faces withe a cube that has four (or a cylinder divided into four sections) and add two coils behind the cube with a ninty degree angle seperating them, then by switching polarity of the coils the cylinder (or cube) can be rotated in four different steps and positioned with a different side facing a viewer; thus, we create a simple mechanical pixel with four colours. The colors chosen will be Cyan, Magenta,Yellow and White, as CMYK are the colors for print based image not light based (RGB).
White replaces Black in this pixel as the Black (K) will be genrated by the extra Greyscale layer.

The greyscale layer consists of a black shell that rotates around the pixel and hides it partially or fully. The more the masking layer hides the darker the color will appear for a person looking at it from a distance. Our eye cannot resolve geometry and color when the pixel is smaller and then the colors mix together and the geometry fuses, that is how all light pixel displays work.

This greyscale masking layer is also controlled by the same coils controlling the cube. With every full rotation of the cube the masking layer hides 1% to 10% of the pixel. So it can be designed to have at least 10 to 100 shades of grey. The masking layer is connected to the cylinder rotation by simple planetary gear system or a screw type gear with gear reduction of 1/10 or 1/100.

The final result is a pixel that can display four colours and adjust the grey shade in each. It is a mechanical pixel with full shades of CMY and controlled by two coils. An assembly of such pixels has the potential to display a full color picture. The refresh rate of such display would depend on the final construction. If a system with 30 Hz refresh rate can be achieved then the result is a mechanical video display.

Would you like to change the color of your room with one click ? or you would like to add a painting to the wall with one other click ?

3D Printer New Extruder Technology (VWE)

Variable Width Extruder VWE

This is an article about VWE a new extruder technology concept that aims to increase build speed , quality and strength in a 3D printer. VWE stands for variable width extruder, it practically is a change in the method a plastic film is deposited on the print bed and layers are stacked.

All standard FFD (Fused Filament Deposition) printers use a nozzle with a circular opening that deposits constant width in all directions. The machine is programmed to deposit along certain paths to create the final geometry. In places where thick walls are needed the nozzle travels several times usually in a slightly overlapping "Snail like path".

VWE is a nozzle with rectangular slit (Shown in the video below) . The slit has variable width that changes depending on the wall thickness being printed. This allows the printer to build the part walls (Sides , reinforcing ribs , any geometry wider than the standard nozzle width ) with one pass.

However, printing variable width depending on location and orientation requires that the nozzle reorients to keep the nozzle perpendicular to the movement direction. Thus a VWE nozzle requires tow additional actuators , one to control the nozzle width and an additional servo motor at base to orient the nozzle on axes Z.

Further a VWE extruder would require a new algorithm to generate path and nozzle width adjustment and orientation adjustment. This complicates a bit the calculations to generate the path, which is not a burden for todays computer.

A change of deposition rate would need an balance of feed rate which can also be adjusted and controlled by programming.

A VWE equipped printer can deposit walls in on path and make 100% fill parts with one path if the total part width is less that the maximum nozzle opening width .

Layers deposited by VWE are more homogenous , consistent and are deposited at same time in a wall, thus with less temperature variation and better bonding between layers.

I have not developed a working prototype of VWE, but if anyone is interested in developing such nozzle I would be glad to cooperate on it. If someone develops VWE nozzle independently , I would only request to reference me as original creator of the concept.

A Solid Lighter than Air

Maybe when you hear lighter than air, the first thing that comes to mind would be a Zeppelin or an Aerogel. Well, a Zeppelin is lighter than air when the gas inside has a lower density and is trapped in a flexible membrane. The Zeppelin is not a solid.

Aerogel is one example of a porous solid that goes to the limits of density by being cellular with minimum solid material. It is 99% air and thus is it still heavier than air.

A solid that is lighter than air, by my definition is a non fluid material that has a density lower that air density on earth's surface which is about 1200 grams per meter cube.

So how is this solid achievable ?

I guess you have heard of Graphene, the lately famous super strong material, that got Andre Geim and Konstantin Novoselov a noble prize in Physics in 2010. I will use this strong material to describe a solid lighter than air that can be first made in laboratory and maybe in the future produced in large scale for projects of aviation, space or construction.

Graphene is described as "atomic-scale hexagonal lattice made of carbon atoms" shown in the picture below. A one atom layer material.

Wikipedia

When you look a round you, remember that every meter cube of air has about 1200 grams of O2 , CO2, N2 and other gas molecules floating it. So, let us take one meter cube of air, push all atoms in it to the surface of that cube and connect them to form a wall. We end up with a solid cube with a vacuum within it. This cube has 1200g of material making its surface shell and a vacuum inside, so it has the same density of Air (Even same atoms).

We could do the same thought exercise but replace this time the Carbon, Oxygen, Hydrogen and Nitrogen atoms with  only Carbon. Then, we connect the Carbon atoms to form a Graphene solid cube of carbon with a vacuum "trapped" inside. Graphene is measured to be one of the strongest materials discovered so far, the common story to describe the strength of it, is that if you place a pen on a sheet of Graphene and make an elephant stand on the pen, it will not pierce the sheet.

A meter cube volume for a real Experiment is definitely not a practical starting volume for a laboratory. The real experiment could be done to produce a 1 cm diameter sphere of graphene in Vacuum. This sphere would trap vacuum, resist collapsing and when placed in Air Environment, it would be lighter than air.

I went through the trouble of doing calculations for the smallest sphere with a shell that would be lighter than air considering the volume is takes, in other words that smallest sphere that can be lighter than air. The result is :

1.90121 µm radius or 3.80242 µm diameter.

If you are into physics and math... continue reading.

Below are my approximate calculations, please correct me if you spot a mistake.

Assuming that carbon atoms form perfect flat Hexagone geometry, the area of an hexagon with L as edge length is :

Distance between carbon atoms in a Hexagone assembly is 0.142 nm.
Area of a sphere is 4πR^2.
Dividing those two values with a selected starting radius of 1 meter, we could identify how many hexagons would cover the surface of that sphere.

When assembled, every hexagon shares a side with another hexagon next to it, so the number of Carbon atoms involved in the construction of this sphere would be two atoms per hexagon times the number of hexagons.

Knowing the mass of one carbon atom (1.992 x 10^-23 g) it is then possible to calculate the mass of a sphere.
Knowing the volume, we finally have the Density.