How Magna Doodle Works

The Magna Doodle is basically a magnetic drawing board. It has the following pieces:

To work the Magna Doodle, you write something on the surface with the magnetic pen. When you want to erase what you have written, slide the sliding magnet to one side or the other (it works in both directions).

Now, let's look at the pieces in more detail.

The magnetophoretic display panel is what makes the Magna Doodle unique.

This magnetic display has the following structure:

The walls of the middle, honeycombed lattice are less than 0.02 inches (0.5 mm) thick. Each cell of the lattice is filled with a thick liquid suspension or dispersion medium filled with tiny magnetic particles. The liquid dispersion medium is designed so that the particles can be pulled through the liquid in response to magnetic force applied by the pen or eraser, but they will not change their position (float or sink) due to gravity. To do this, the liquid has special properties:

The middle layer is latticed so that there is always an even distribution of the magnetic particles across the entire surface of the display.

Now that we have seen the display, let's look at the pen.

The magnetic pen is simply a piece of plastic with a small magnet in the tip. The field of the magnetic pen is strong enough to penetrate the plastic and pull the particles through the thick liquid.

The magnetic pen is ergonomically styled so that anyone, especially little children, can grip it comfortably. The pen is usually tied to the Magna Doodle by an attached string. Some Magna Doodles also come with "shape stampers," which are simply magnets in shapes like diamonds, triangles and circles.

Writing is but one use of the Magna Doodle. You must also be able to erase it, so let's look at the eraser.

The magnetic eraser consists of a bar magnet in a plastic slider.

The magnetic eraser sits in the back of the Magna Doodle behind the display, and it can't be seen from the front. The eraser fits in a groove on the case that allows it to slide freely from one side to the other.

Now let's look at the final component: the case.

The plastic case holds everything together.

It has two pieces:

A front piece that:

A raised back piece that:

Now that we have seen each part, let's see how the Magna Doodle works!

Let's slide the magnetic eraser across the Magna Doodle and start with a clean display. The front of the display is blank (white), and the back has all the particles. They were pulled to the back by the magnetic eraser.

If you look closer at each cell, you will see that the magnetic eraser has aligned the particles to one side!

Now, if you move the magnetic pen along the display, the magnet on the pen pulls the tiny particles away from the back side to the front side, forming a line. Note that the magnet pulls particles from adjacent cells and aligns them in the direction of motion (in this case, to the right).

Because the particles are light and the liquid dispersion medium is thick, gravity will not pull the particles forming the lines back to the other side. What is written will remain undisturbed.

To erase the display, slide the magnetic eraser across the back of the display. As this is done, the magnetic eraser pulls the particles forming the lines from the front side to the back side and aligns them in the direction of the motion. The thickness of the liquid dispersion medium prevents them from floating to the surface, so the front side remains clean.

The Magna Doodle is a wonderful toy that allows children (of all ages) to draw and re-draw pictures and words without wasting paper or creating chalk dust. When traveling in a car on a long trip, one can draw for hours without creating lots of trash or having to sharpen pencils. Magna Doodles have been used by teachers to help students practice writing and learn words. Magna Doodles have been used in some unexpected places, too:

There are many creative ways to use this wonderful toy. For lots more information, check out the links on the next page.