The importance of 4-wire resistive touch screens

Views: 202     Author: Reshine Display     Publish Time: 2023-08-14      Origin: Site


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The importance of 4-wire resistive touch screens

Even though there are many cutting-edge touchscreen options on the market, 4-wire resistive touch panels are still used in low-cost touchscreen applications. Among the numerous resistive touch screens, this is the most fundamental. A layer of dielectric spacer dots that are invisible to the unaided eye separates the top and bottom transparent conductive sheets of 4-wire resistive touch screens from one another. Voltage is applied across the entire conducting surface of the uniformly resistive sheets.

What occurs when a touch is made on 4-wire resistive touch screens?

In 4-wire resistive touch screens, the two opposite sides of each layer are covered by conductive bus bars. Bus bars are found on the left and right margins of one layer while they are top and bottom on the other layer. With the positive connection to one bar and the negative connection to the other, the controller applies a DC voltage across one of the layers, resulting in a voltage gradient via the layer's conductive coating.

The controller employs the opposite layer as a voltage probe to read the voltage at the touch point when a touch event takes place, bringing the opposite layer into contact with the voltage layer. The touch point's location in plane X or Y is then determined by the controller.

To get to the other plane, the controller flips the layers' functions so that the same thing happens in X rather than Y, or vice versa. This layer function flipping occurs at a rate of more than 100 times per second, resulting in no lag in reporting of X and Y coordinate readings.

4-Wire Resistive Touch Screen Applications

4-wire resistive touch screens are typically preferred for applications that require very little power. Because this touchscreen technology is voltage-controlled and does not require much current, it is commonly found in portable battery-powered devices.

This touch screen makes use of the majority of the sensor's surface as the active area where a touch can be detected. It is useful in applications where space is at a premium, such as hand-held devices.

What limitations do 4-Wire Resistive Touch Screens have?

Drift in TouchPoint Position

Because 4-wire is voltage operated, the electrical properties of the conductive layers, buss bars, and flex tail cannot vary. The voltage readings from the X and Y layers will change, causing the touch point to move.

This is primarily due to the extreme temperature variations caused by the sensor's heating and cooling as a result of environmental conditions.

Limited Sensor Life

Poor sensor life is another significant issue with 4-wire resistive touch screens. With finger operation, only about 4 million touches or less can be anticipated on the same spot; this problem is made worse with a stylus. A few sharp strokes with a fine-point stylus are all it takes to destroy a 4-wire resistive touch sensor. This is because the polyester switch layer-based ITO is fragile.

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