LCD writing tablet functional principal

Cholesteric liquid-crystal drawing tablet

Prelude

I recently stumbled across drawing tablets seemingly works by the means of magic, the search term is: LCD writing tablet I have a thing for daylight viewable screens, so the allure was irresistible for me.

After one quick trip to the local hardware store, and subsequently the local hacker space, i was able to examine the technology first hand, and for low monetary cost too, i might add.

Properties

The properties are as follows:

• Daylight viewable
• Passive working principle (only requires power to clear the display)
• Pressure amount sensitivity (light pressure = thin line, hard pressure = thick line)

Layers

The tablet consists of a sandwich of 3 layers:

• A dark background
• A layer of cholesteric liquid-crystals
• A piece of translucent plastic

Functional principal

The means of function of this device, is merely a property of how the cholesteric liquid-crystal work:

"crystals flow at different rates, depending on the direction of pressure being applied"

"anisotropic flow causes the molecules to order themselves to reflect light in those places where a stylus touches the plastic sheet."

Sources:

1. How Liquid Crystal Displays Work in an eWriter - new.nsf.gov
2. Cholesteric liquid crystal - wikipedia.org
3. Anisotropy - wikipedia.org

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