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.

ontwerpvoorbeeld: resistief touchscreen

Een apparaatingenieur speelt een cruciale rol bij het ontwerpen van gebruikersinterfaces voor mobiele apparaten. Eén van die interfaces is het resistieve touchscreen, dat in principe uit twee metalen lagen bestaat: een flexibele bovenlaag en een stijve onderlaag, gescheiden door een smalle opening. De hoge weerstand tussen deze twee lagen is een belangrijk kenmerk van dit ontwerp. Wanneer een gebruiker het scherm aanraakt, maken de twee lagen contact op een specifiek punt dat het aanraakpunt wordt genoemd. Dit contact vermindert de weerstand tussen de lagen, waardoor de elektrische eigenschappen van het touchscreen op dat punt effectief veranderen. Om echter nauwkeurig de precieze locatie van het aanraakpunt te kunnen bepalen, moet het touchscreen vereenvoudigd worden tot een eendimensionaal systeem. De bovenste laag, gekenmerkt door zijn lengte, soortelijke weerstand en dwarsdoorsnede-oppervlak, is conceptueel verdeeld in twee delen op het contactpunt. De weerstanden van deze twee secties zijn evenredig met hun lengte. Door een voltagesbron tussen de twee uiteinden van de bovenste laag aan te sluiten, wordt het circuit omgezet in een voltagesdelerconfiguratie. De voltagesval op het contactpunt hangt af van de weerstanden van de twee delen van de toplaag. Door de weerstandswaarden in de voltagesdelervergelijking in te vullen en deze op te lossen, kan een relatie worden afgeleid tussen de voltagesval op het contactpunt en de positie ervan. Dankzij deze relatie kan het apparaat de exacte locatie van het aanraakpunt berekenen op basis van de verandering in voltage. Dit betekent dat elk aanraakpunt overeenkomt met een afzonderlijke voltage, waardoor het systeem nauwkeurig de locatie van de aanraking van de gebruiker kan bepalen. Deze precisie is van cruciaal belang voor de functionaliteit van de touchscreeninterface en zorgt ervoor dat deze nauwkeurig reageert op de invoer van de gebruiker.

Ontwerpvoorbeeld: resistief 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 ...

Education

JoVE Core

Electrical Engineering

Elektrotechniek

Unit 1

Basics of Electric Circuits

Basisbeginselen van elektrische circuits

KEY TERMS AND CONCEPTS

BELANGRIJKE TERMEN EN CONCEPTEN

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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kirchhoff's current law

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design example: resistive touchscreen

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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Resistive Touchscreen Voltage Mapping

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