Understanding Waterproofing
Waterproofing is defined by an IP rating of IP65 or greater. Monitors rated IP66 or IP67 must accomplish two key objectives:
- Resist water on external surfaces
- Prevent water from infiltrating internal components
Both are challenging due to water’s unique ability to interfere with electronics and penetrate tiny gaps. Water possesses both chemical properties (carrying electrical charge) and physical properties (hydrostatic pressure), both of which impact waterproof touchscreen monitors.
Waterproof Touchscreen Monitors and Water Pressure
When submerged, a monitor is exposed to increasing hydrostatic pressure, which depends on depth and elevation. Typically, waterproof monitors are tested at a depth of 1 meter for 30 minutes. To pass the test, the touchscreen must function without pressure-induced failure, and internal components must remain dry.
Keeping Things Dry
Waterproof monitors rely on epoxy seals to bond glass to stainless steel and prevent leaks. However, epoxy is an insulator and cannot be used for inputs and outputs (I/Os). Instead, waterproof touchscreen I/Os use:
- Corrosion-resistant steel air/watertight seals
- Rubber gaskets to block water entry
Handling Water Pressure
Touchscreens can be calibrated to different pressure sensitivities to ensure reliable operation in wet environments.
- Resistive touchscreens can be adjusted to ignore small amounts of water pressure.
- Washdown computers often feature a screen lock to prevent accidental input from high-pressure water jets during cleaning.
Waterproof Touchscreens and Electrical Currents
Anyone who has used a smartphone in the rain knows how water can cause unintended inputs. This happens because water conducts electricity, which can interfere with touch registration.
- Resistive touchscreens are unaffected because they register touch through physical pressure.
- Projected capacitive (PCap) touchscreens, however, register electrical signals to detect input.
- To prevent ghost touches, waterproof P-Cap screens are engineered to be less sensitive to stray electrical signals and more sensitive to direct touches from fingers or styluses.
- In environments with seawater, P-Cap screens may be problematic because salt increases voltage potential, leading to unintended inputs.
Time and Testing for Waterproof Touchscreens
For a computer to be rated IP66 or greater, it must pass rigorous testing. However, test specifics can vary between manufacturers.
When purchasing a waterproof touchscreen monitor, it’s crucial to:
- Inquire about IP testing specifics
- Understand the test duration and conditions
By knowing these details, you can ensure that your monitor meets the necessary waterproofing standards for your environment.
