National Engineers Month

	Activities by Grade	K - 2		5 - 8
		3 - 4		9 - 12

Photocopier

"The reproduction of images in a photocopier is called the xerographic process.  The key component of the process is the photoreceptor.  Images to be copied are exposed to light and focused onto the surface of the electrically-charged photoreceptor.  The image is then transferred to paper using dry ink called toner.  Heat and pressure permanently fix the image to the paper.  After the copy is produced, the photoreceptor is cleaned and made ready for the next copy.  Photocopiers are essential tools for communication in schools, churches, government, and businesses.  The xerographic process was invented in 1938 by CHester Carlson whose ideas became the foundation for the company now known as Xerox Corporation"
Marie A. Divine, manager
Technical Operations,
An Office Equipment Company

What you need:

• graphite shavings (from a pencil)
• waxed paper
• scissors
• acetate (overhead transparency)
• glue
• 6" (15 cm) cardboard square
• fine-toothed plastic comb
• wool cloth
• white paper

Directions:

1. Sprinkle a thin film of graphite shavings on waxed paper.
2. Cut several layers of acetate strips in the shape of a 5" (12.5 cm) letter, such as L or F, and glue them to the cardboard square so the letter appears backward.  Glue several layers together so the letter is raised above the cardboard at least 1/4" (0.5 cm).
3. Electrically charge the plastic comb by rubbing it against the wool cloth.  Carefully rub the comb against the letter to transfer the charge.
4. Hold the acetate letter an inch (2.5 cm) above the graphite shavings.  The shavings should jump from the waxed paper to the letter.  If they do not, repeat step 3 to be sure you transferred the electric charge.
5. Press white paper against your letter to create a permanent "copy."

How it works:

In electrostatic photocopiers, a metal plate is charged with static electricity and exposed to the image to be copied.  A light shines on the plate, leaving only the dark image charged.  Toner blown across the plate sticks to the charged area, reproducing the image.  The image is then transferred and fixed to paper.  In this simulations, the graphite shavings represent the toner in a copier.  Rubbing the charged comb against the letter is similar to transferring a static charge to the metal plate.

Stretching Technology:

Once the acetate loses its charge, the graphite shavings no longer stick to it.  Create a way to make permanent reproductions of images.

Research Chester Carlson's original xerographic process and compare it to the copying process in a modern photocopier.  Record findings in your technology journal.