Unbeknownst to many users, touchscreen devices contain multiple layers. Each layer plays a critical role in the device’s operation, bringing it together so that it can respond touch-based commands with the appropriate action. In a previous blog post, we discussed the layers of a typical capacitive touchscreen device. In this post, we’re going to explore the layers of a resistive touchscreen device.
The upper layer of a resistive touchscreen device is made of transparent glass or plastic with an electrically conductive coating, such as indium tin oxide (ITO). The conductive coating is placed on the underside of the upper layer so that it can make it contact with the bottom layer. Like capacitive touchscreen devices, resistive touchscreen devices create a uniform voltage, and this electrical charge is used to help determine the location of a user’s touch. Touching the surface of a resistive device causes the upper layer to press into the bottom layer. This allows some of the current to flow between the two layers, thereby telling the device when and where the touch occurred.
There’s also a middle “spacer” layer in resistive touchscreen devices. This layer is important because it separates the upper and bottom layers, which contain the electrically conductive coating (e.g. ITO). Without the space layer, these two layers would press together at all times. And as a result, the device would constantly register touch commands even if the user wasn’t touching it. The middle layer in a resistive touchscreen device is simply a layer of air or inert gas. It doesn’t contain any special materials or technology. Rather, it lives up to its namesake by creating “space” between the two other layers.
The third and final layer in a resistive touchscreen device is the bottom layer. The bottom layer is designed in a similar manner as the upper layer. However, the bottom layer contains the electrically conductive coating on the top so that it creates the flow of current when the two layers make contact.
This is just a general overview of the three different layers of resistive touchscreen devices. Different manufacturers use different techniques and configurations to produce their resistive touchscreen devices. Some, for example, feature a four-wire configuration, whereas others feature a five- or eight-wire configuration. Regardless, though, all resistive touchscreen devices identify touch commands by pressure rather than measuring change of capacitance like capacitive touchscreen devices.