Guide to Touch Screens

Kinds of Touch Screens include the following:

Resistive touch screens

• Resistive touch screens have conductive and Resistive layers that cause a change in electrical current when touched, which is then processed by a controller.
• They are relatively cheap, but they only have about 75% clarity because of the screen overlay. Newer models use glass finishes and premium films to improve clarity up to 85%.
• They are not affected by dust, water, or other outside elements, but the Resistive layer is easily damaged by tension and pointed objects.

• Surface Wave touch screens emit ultrasonic waves over the panel, which are disturbed when the screen is touched. This is then sent to the controller, which processes it into a user command.
• They are easily damaged by outside elements, such as heat and moisture.
• The surface also requires regular maintenance, since physical contaminants can affect the screen’s sensitivity.

• Capacitive touch screens are coated with indium tin oxide, which emits a constant stream of electrons over the screen. When a finger touch disturbs these electrons, the event is sent to the controller for processing.
• Some models require a special stylus with a conductive tip to ensure consistent pressure at every touch.
• They have relatively high clarity and are not slowed down by outside elements.

• Infrared touch screens use a grid of Infrared beams that are interrupted when the screen is touched.
• Older models used thermal surfaces that registered slight changes in temperature caused by finger presses. These had to be operated with warm fingers to increase screen sensitivity.
• They are the most durable touch screens available and are commonly used in military applications.

• Strain Gauge touch screens have sensitive gauges that detect deflection on the screen’s surface when touched.
• They are supported by springs on four corners, allowing them to detect touch on the z-axis or the depth of deflection of each touch.
• They can be programmed to resist extreme deflection caused by force, making them ideal as vandal-proof screens in public places.

• Optical Imaging touch screens have image sensors around the corners and Infrared backlights illuminating the panel.
• The backlights detect touches as shadows and use the sensors to determine the site of the pressure.
• They can be scaled to fit different screen formats and are commonly used for large display screens.

• Dispersive Signal touch screens detect vibrations transferred by finger touches to the glass panel. The touch is located using algorithms programmed into the screen.
• They are not affected by contaminants and have high optical clarity.
• They can be operated with bare fingers and styluses.

• These touch screens use piezoelectric transducers to convert mechanical energy from the touch into electrical signals. These signals are then converted into audio files, which are matched with audio profiles programmed onto the screen.
• They do not require a separate grid and are made entirely of glass, providing maximum clarity, accuracy, and durability.
• They can work with any pointing device and are not affected by dust and scratches.

Clarity: Choose a high-resolution touch screen that displays accurate color and detail. Make sure the edges are well-defined and that small texts are clear and readable. Look for durable glass panels with a protective coating to prevent scratches.

Sensitivity: Choose a touch screen that requires little pressure to operate, but does not respond to soft accidental presses. Look for a stylus-operated model if you tend to rest your hand on the screen while working.

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Touch Screens