Describe the working of a resistive touchscreen.
1 Answer
A resistive touchscreen is a type of touch-sensitive input device commonly used in various electronic devices like smartphones, tablets, and certain types of industrial control panels. It operates on the principle of changes in electrical resistance when pressure is applied to the surface of the screen.
Here's how a resistive touchscreen works:
Layered Structure: The resistive touchscreen consists of two main layers with a gap between them. These layers are usually made of a flexible material like polyester. The layers are:
a. Top Layer (Flexible and Transparent): This layer is often made of a clear, conductive material like indium tin oxide (ITO). It serves as the top surface of the touchscreen and is in direct contact with the user's finger or a stylus when pressed.
b. Bottom Layer (Flexible and Transparent): This layer is also made of a clear, conductive material, usually ITO. It is located beneath the top layer, facing it, and remains stationary.
Insulating Separators: To maintain a gap between the two conductive layers, small insulating dots or separators are placed along the edges. These dots prevent the top and bottom layers from making direct contact when the screen is not being pressed.
Conductive Coating: Both the top and bottom layers are coated with a resistive and conductive material. When no pressure is applied, the layers do not touch due to the insulating separators, creating an air gap between them.
Electrical Current: When a user applies pressure to the top layer by touching it with their finger or a stylus, the two conductive layers come into contact at the point of pressure. This creates an electrical circuit in that specific location.
Voltage Division: The touchscreen controller sends a low-voltage electrical current across the top layer, typically from the four corners. The electrical current flows evenly through the entire layer.
Measurement of Voltage Change: When the top layer comes into contact with the bottom layer due to pressure, the electrical resistance at that point changes. This change in resistance alters the voltage distribution across the top layer.
Touch Location Determination: The touchscreen controller measures the voltage at various points on the top layer and analyzes the point with the greatest voltage drop. This drop corresponds to the location where the user applied pressure and completes the electrical circuit between the two layers.
Data Processing: The touchscreen controller then translates the touchpoint coordinates into digital data, providing the exact location of the touch on the screen.
User Interface Interaction: The device's operating system or software processes the touch data and initiates the appropriate action, such as opening an app, scrolling, zooming, or any other touch-based interaction.
It's worth noting that resistive touchscreens are generally less sensitive and responsive compared to capacitive touchscreens (used in most modern smartphones). However, they can be operated with a finger, gloved hand, or stylus and can work even if the surface is dirty or scratched, making them suitable for certain industrial applications and rugged environments.
Here's how a resistive touchscreen works:
Layered Structure: The resistive touchscreen consists of two main layers with a gap between them. These layers are usually made of a flexible material like polyester. The layers are:
a. Top Layer (Flexible and Transparent): This layer is often made of a clear, conductive material like indium tin oxide (ITO). It serves as the top surface of the touchscreen and is in direct contact with the user's finger or a stylus when pressed.
b. Bottom Layer (Flexible and Transparent): This layer is also made of a clear, conductive material, usually ITO. It is located beneath the top layer, facing it, and remains stationary.
Insulating Separators: To maintain a gap between the two conductive layers, small insulating dots or separators are placed along the edges. These dots prevent the top and bottom layers from making direct contact when the screen is not being pressed.
Conductive Coating: Both the top and bottom layers are coated with a resistive and conductive material. When no pressure is applied, the layers do not touch due to the insulating separators, creating an air gap between them.
Electrical Current: When a user applies pressure to the top layer by touching it with their finger or a stylus, the two conductive layers come into contact at the point of pressure. This creates an electrical circuit in that specific location.
Voltage Division: The touchscreen controller sends a low-voltage electrical current across the top layer, typically from the four corners. The electrical current flows evenly through the entire layer.
Measurement of Voltage Change: When the top layer comes into contact with the bottom layer due to pressure, the electrical resistance at that point changes. This change in resistance alters the voltage distribution across the top layer.
Touch Location Determination: The touchscreen controller measures the voltage at various points on the top layer and analyzes the point with the greatest voltage drop. This drop corresponds to the location where the user applied pressure and completes the electrical circuit between the two layers.
Data Processing: The touchscreen controller then translates the touchpoint coordinates into digital data, providing the exact location of the touch on the screen.
User Interface Interaction: The device's operating system or software processes the touch data and initiates the appropriate action, such as opening an app, scrolling, zooming, or any other touch-based interaction.
It's worth noting that resistive touchscreens are generally less sensitive and responsive compared to capacitive touchscreens (used in most modern smartphones). However, they can be operated with a finger, gloved hand, or stylus and can work even if the surface is dirty or scratched, making them suitable for certain industrial applications and rugged environments.