Buzz
If you’re a parent, chances are you’ve encountered this popular toy. Here’s a brief overview: The Magna Doodle is a drawing device featuring a white display and a stylus for creating images. As you sketch, a striking black line appears on the white surface (a fascinating effect worth witnessing in person at a toy store). Located at the base is a slider that, when moved, instantly and thoroughly clears the screen (another impressive feature).
Children adore the Magna Doodle, likely because of the bold lines it produces. Interestingly, the pen requires minimal pressure—light or heavy touches yield the same result (unlike crayons). Parents appreciate the Magna Doodle for its mess-free design, as the pen lacks ink or paint. The pen’s tip is a smooth metal piece, making it impossible to mark walls or other surfaces.
But what makes a Magna Doodle function? It consists of four key components:
- The device features two plastic layers, stacked together. The top layer is transparent and serves as the drawing surface.
- Sandwiched between these layers is a honeycomb grid that maintains separation. This grid is visible on the screen, ensuring even spacing and dividing the interior into small compartments.
- Within these compartments lies an opaque white fluid (similar to thick milk).
- Suspended in this fluid are tiny black magnetic particles made of iron oxide.
When the blunt metal tip of the pen, which acts as a small magnet, touches the front screen, it pulls the black magnetic particles through the liquid to the surface, making them visible. These particles remain on the surface due to the liquid's thickness and the balanced density between the particles and the liquid. To erase the screen, the slider activates a magnet that moves across the back, pulling the particles away from the surface and allowing the white liquid to conceal them.
Explore these resources for further information:
- How Magna Doodle Works
- Patent #4,143,472: Displaying magnetic panel and its display device
- Patent #5,151,032: Magnetophoretic display panel
