Name: resistive touchscreen voltage mapping
Uploaded: 2024-04-11T12:48:28.000Z
Duration: 1 min 14 s
Channel: JoVE

K12 Standards

Texas Essential Knowledge and Skills

High School

Specialised Topic in Science

112.51.c.1.

112.51.c.2.D.

Design Example: Resistive Touchscreen

A device engineer is tasked with designing a resistive touchscreen interface for a mobile device. It consists of two conductive layers: a flexible upper layer and a rigid lower layer, separated by a narrow gap.
The resistance between the two layers is high. Upon touching the screen, the two layers make contact at a point called the touchpoint, reducing the resistance between the layers.
To determine the precise touchpoint location, the touchscreen is simplified to a one-dimensional system.
The top layer is characterized by its length, resistivity, and cross-sectional area and is divided into two parts at the touchpoint with resistances proportional to their length.
If a voltage source is connected between the two ends of the top layer, the circuit resembles a voltage divider circuit, and the voltage drop at the touchpoint depends on these two resistances.
Substituting the resistance values and solving the equation gives the relation between the voltage drop at the touchpoint and its position.
At each touchpoint, the voltage is distinct, which helps to pinpoint the location accurately.

design example: resistive touchscreen

A device engineer plays a crucial role in designing user interfaces for mobile devices. One such interface is the resistive touchscreen, which fundamentally consists of two metallic layers: a flexible upper layer and a rigid lower layer, separated by a narrow gap. The high resistance between these two layers is a key characteristic of this design.
When a user touches the screen, the two layers make contact at a specific point known as the touchpoint. This contact reduces the resistance between the layers, effectively changing the electrical properties of the touchscreen at that point.
However, to accurately determine the precise location of the touchpoint, the touchscreen needs to be simplified as a one-dimensional system. The top layer, characterized by its length, resistivity, and cross-sectional area, is conceptually divided into two parts at the touchpoint. The resistances of these two sections are proportional to their lengths.
Connecting a voltage source between the two ends of the top layer transforms the circuit into a voltage divider configuration. The voltage drop at the touchpoint depends on the resistances of the two sections of the top layer.
By substituting the resistance values into the voltage divider equation and solving it, a relationship can be derived between the voltage drop at the touchpoint and its position. This relationship allows the device to calculate the exact location of the touchpoint based on the change in voltage.
This means that each touchpoint corresponds to a distinct voltage, enabling the system to accurately pinpoint the location of the user&#39;s touch. This precision is critical for the functionality of the touchscreen interface, ensuring it responds accurately to the user&#39;s input.

A device engineer is tasked with designing a resistive touchscreen interface for a mobile device. It consists of two conductive layers: a flexible upper ...

Education

JoVE Core

Electrical Engineering

Unit 1

Basics of Electric Circuits

KEY TERMS AND CONCEPTS

resistive touchscreen voltage mapping

A resistive touchscreen uses voltage mapping to locate a finger touch on a mobile device. It is built from two metallic layers. The top layer is flexible, and the bottom layer is rigid. A narrow gap separates them, and the high resistance between the layers is an important part of the design.

When a user touches the screen, the two layers meet at one point. That contact point is called the touchpoint. The touch lowers the resistance between the layers at that spot and changes the electrical behavior of the screen. This change is what lets the system detect input.

To find the exact touch location, the touchscreen is simplified as a one-dimensional system. The top layer is described by its length, resistivity, and cross-sectional area. At the touchpoint, the top layer is split into two parts. The resistance of each part depends on its length.

A voltage source is connected to the two ends of the top layer. This setup creates a voltage divider circuit. The voltage drop at the touchpoint depends on the resistance of the two sections. By using the voltage divider equation and solving for position, the device can match each touchpoint to a distinct voltage and calculate the exact touch location.

Resistive Touchscreen Voltage Mapping

charge and current

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voltage

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kirchhoff's current law

Kirchhoff's Current Law at Circuit Nodes

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kirchhoff's voltage law

Voltage Balance in Closed Circuit Loops

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voltage dividers

Series Resistors and Voltage Split

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A resistive touchscreen uses voltage mapping to locate a finger touch on a mobile device. It is built from two metallic layers. The top layer is flexible, and the bottom layer is rigid. A narrow gap separates them, and the high resistance between the layers is an important part of the design. When a user touches the screen, the two layers meet at one point. That contact point is called the touchpoint. The touch lowers the resistance between the layers at that spot and changes the electrical...

key terms and concepts

Learn how a resistive touchscreen uses two conductive layers, a voltage divider, and touchpoint resistance changes to locate a finger on a mobile device.

Resistive Touchscreen Voltage Mapping | JoVE K12

JoVE Core Electrical Engineering offers easy-to-understand animated videos that cover fundamental concepts of electric circuits along with circuit analysis techniques. It incorporates first-order and second-order circuits using operational amplifiers and circuit transformation concepts. The inclusion of practical design examples and real-world applications through scientist-in-action videos adds significant educational value, making complex concepts accessible.

electrical engineering

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112.51.c.1.A.

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112.51.c.1.B.

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112.51.c.1.C.

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112.51.c.1.D.

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112.51.c.1.E.

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112.51.c.1.F.

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Resistive Touchscreen Voltage Mapping

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