Resistive Touch Panels
Rugged TFT Displays
Resistive Touch Panels (RTP) have traditionally been the most common touch panel technology in the industrial market.
There are two main types of resistive touch panel, 4-wire, and 5-wire RTP. Each consists of a two-layer construction for determining the X and Y coordinates. Typical applications include handheld devices or any product that requires a low-cost single touch solution.
4-WIRE – RESISTIVE TOUCH PANEL
The most cost-effective touch panel is the 4-wire RTP. These have an Indium Tin Oxide (ITO) resistive coating on the inner side of each layer to create the X-axis and the Y axes. Voltage is then applied to each layer individually. Once touched both layers make a contact, the coordinates for the X and Y axis are then calculated using a voltage divider.
One disadvantage to the 4-wire RTP is that the flexible coversheet (top layer) acts as one of the axes as well as a uniform voltage gradient. Certain factors can cause the linearity and accuracy on this axis to decrease, including for example environmental conditions and high frequency of operation.
Occasional re-calibration may be required to maintain a level of touch point accuracy. Typical lifetime durability for repeated touch on a single spot is 1 million times, based on a finger touch.
5-WIRE – RESISTIVE TOUCH PANEL
The 5-wire resistive touch panel offers a similar construction and design concept to the 4-wire RTP. The 5-wire RTP only uses the bottom layer to create both X and Y-axis coordinates and the top layer acts as a voltage probe. This results in excellent stability, durability, sensitivity, and reliability due to the top layer not being used for one of the axes.
The 5-wire RTP is an ideal touch panel solution for applications where touch durability and reliability are crucial or the touch input is potentially from an inanimate object.
A few benefits of the 5-wire RTP are:
- A constant level of accuracy, even if the top layer is damaged
- Touch response and accuracy is unaffected by harsh environmental conditions
- Calibration only required after initialization of the system
We aim to provide everything you need to integrate your display and touch panel into your system. We can supply controller boards that allow you to easily interface to your systems and equipment. Interface examples include USB, RS232, and PS/2. Operating systems supported include Windows, CE, and Linux.
We at Relec Electronics aim to find the best solution for your application. Our fully-trained technical staff has the knowledge to help you from sourcing and manufacturing. We also carry stock on most Display items, so get in touch today.
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