A FREE 3D volumetric display from scraps lying around the workshop.
This is my first instructable so please be forgiving.

The display has a very low resolution, 4 x 4 x time.

Images look better when you stand away from the screen a bit.

I have included a movie.(The camera is slowly revolving around the display)

CIMG2070.MOV
Download

Step 1: Concept

The basic principle of the display is to move a normal 2D display up and down really fast while changing the image on the screen.

A example of the is concept can be shown by when you move a pen up and down very quick the pen seem to become a flat screen. eg. the second picture

So all up we are multiplexing x , y and time.

A better explanation is provided in the following (under sweep volume display):
http://en.wikipedia.org/wiki/Volumetric_display

Step 2: The Moving Mechanism

Here is the the moving mechanism.

I salvage the whole thing from a printer from a old printer.

Bolt it down to the base.

On the secondary gear drill a small hole about 1.5cm - 2.5cm from the center. The further it is from the center the higher your volume.

Make the pivot be bending a bit of wire.

Make the arm from about 6cm of wire bent in to a loop at each end and soldered.

Put a small washer on to the pin then the arm. Finally put the pin through the hole in the secondary gear and bend the other end in to a hook to hold it in place.

Place the secondary gear on to the axle.

I had two problems when I powered up the motor:
a) the gear slipped off the axle
b) the arm was hitting the axle

I solved the first problem be adding a arm that bent around the secondary gear.

The second problem was solved by bending the arm a bit so it when over the axle.

I am powering my motor with a variable DC transformer to select between speeds.

Step 3: Moving Arm

I used a bit of scrap acrylic as the arm because it was fairly flexible.

I made the stand on the right from 2 corner bracket bolted together.

The arm could be replaced by a plastic ruler.

Then I cable tied the arm to the stand. ( the hole was pre-drilled )

The arm is attached to the moving mechanism arm by a length of 20 pound fishing line tied to the loop on the arm and the cable tie on the arm.

When integrating the arm and the gear make sure the gear can drive the arm to a speed where the arm will resonate.

Resonating the arm is like when you put the ruler on the edge of the table and hit the end of the ruler and vibrate up and down for a few seconds.

When the arm resonates properly the arm should become a blur and any marking on the arm will become a vertical line.

Step 4: 2D Screen (4x4 LED Array)

I made this array a while back and found it when i was making the volumetric projector so i used it.

The array has 16 LEDs connected in a x ,y matrix.

Schematic is provided.

The base is plastic lid with holes drilled in it.

A bread board could be used to make the LED array.

Step 5: Vibration Suspention

Due to the use of the C stand the arm moves left and right too much so instead of a straight vertical line this arm will show a really stretched out 8.

I installed a Y suspension system.

Put 2 screws on the corner of the base.

String a long spring ( found in my collection ) across the 2 screws.

Bend a hook out of wire.

Hook the center of the spring to the bottom of the cable tie.

This suspension did improve the vertical line.

Step 6: Electronics

To electronic consists of a clock from the mechanical part of the display, micro processor and LEDs.

It is not necessary to use a micro. It can be replaced by a simple electronic pulse generator which will simply create patterns of moving LEDs.

For the clock I used a infrared switch (from the printer) triggered by a bit of plastic tape sticking out of the secondary gear.

The interface is the small block jointed to the infrared switch by a flexible PCB. The interface powers the switch and modifies the out put to suit the micro.

I connected it on the the micro board with half a IC socket.

The LED array is connected to the micro board by a IC socket as well.

The micro prototype board was another thing i had lying around so i used it.

I won't go into detail how this whole micro setup works because I can't remember half of it.

But the board can be replaced with any micro that that 1 input and have 8 outputs.

The simple idea behind the program is

when clock interrupts

output 0111 line 1 data layer 1
output 1011 line 2 data layer 1
output 1101 line 3 data layer 1
output 1110 line 4 data layer 1

delay for layer space

output 0111 line 1 data layer 2
output 1011 line 2 data layer 2
output 1101 line 3 data layer 2
output 1110 line 4 data layer 2

etc.