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

מהנדס התקנים מקבל משימה לתכנן ממשק מסך מגע התנגדותי עבור מכשיר נייד. הוא מורכב משתי שכבות מוליכות: שכבה עליונה גמישה ושכבה תחתונה קשיחה, המופרדות על ידי פער צר.
ההתנגדות בין שתי השכבות גבוהה. עם הנגיעה במסך, שתי השכבות יוצרות מגע בנקודה הנקראת נקודת מגע, מה שמקטין את ההתנגדות בין השכבות.
כדי לקבוע את המיקום המדויק של נקודת המגע, מסך המגע מפושט למערכת חד-ממדית.
השכבה העליונה מאופיינת באורכה, התנגדותה ושטח החתך שלה והיא מחולקת לשני חלקים בנקודת המגע עם התנגדות פרופורציונלית לאורכם.
אם מקור מתח מחובר בין שני הקצוות של השכבה העליונה, המעגל דומה למעגל מחלק מתח, וירידת המתח בנקודת המגע תלויה בשתי התנגדויות אלה.
החלפת ערכי ההתנגדות ופתרון המשוואה נותנת את היחס בין ירידת המתח בנקודת המגע לבין מיקומה.
בכל נקודת מגע, המתח הוא מובחן, מה שעוזר לאתר את המיקום במדויק.

דוגמה לעיצוב: מסך מגע ההתנגדות

<div style="direction:rtl">מהנדס מכשירים ממלא תפקיד מכריע בעיצוב ממשקי משתמש למכשירים ניידים. ממשק אחד כזה הוא מסך מגע ההתנגדות, המורכב ביסודו משתי שכבות מתכתיות: שכבה עליונה גמישה ושכבה תחתונה קשיחה, המופרדות ברווח צר. ההתנגדות הגבוהה בין שתי השכבות הללו היא מאפיין מפתח של עיצוב זה. כאשר משתמש נוגע במסך, שתי השכבות יוצרות קשר בנקודה ספציפית המכונה נקודת המגע. מגע זה מפחית את ההתנגדות בין השכבות, ומשנה למעשה את המאפיינים החשמליים של מסך המגע באותה נקודה. עם זאת, כדי לקבוע במדויק את המיקום המדויק של נקודת המגע, יש לפשט את מסך המגע כמערכת חד-ממדית. השכבה העליונה, המאופיינת באורכה, בהתנגדות ובשטח החתך שלה, מחולקת קונספטואלית לשני חלקים בנקודת המגע. ההתנגדויות של שני החלקים הללו פרופורציונליים לאורכם. חיבור מקור מתח בין שני הקצוות של השכבה העליונה הופך את המעגל לתצורת מחלק מתח. ירידת המתח בנקודת המגע תלויה בהתנגדויות של שני החלקים של השכבה העליונה. על ידי החלפת ערכי ההתנגדות במשוואת מחלק המתח ופתירתה, ניתן לגזור קשר בין מפל המתח בנקודת המגע לבין מיקומה. קשר זה מאפשר למכשיר לחשב את המיקום המדויק של נקודת המגע בהתבסס על השינוי במתח. המשמעות היא שכל נקודת מגע מתאימה למתח נפרד, מה שמאפשר למערכת לאתר במדויק את מיקום המגע של המשתמש. דיוק זה הוא קריטי לפונקציונליות של ממשק מסך המגע, ומבטיח שהוא מגיב במדויק לקלט של המשתמש.</div>

מהנדס התקנים מקבל משימה לתכנן ממשק מסך מגע התנגדותי עבור מכשיר נייד. הוא מורכב משתי שכבות מוליכות: עליונות גמישה ...

Education

JoVE Core

Electrical Engineering

הנדסה חשמלית

Unit 1

יחידה 1

Basics of Electric Circuits

יסודות מעגלים חשמליים

KEY TERMS AND CONCEPTS

מונחים ומושגים מרכזיים

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

Electric Charge in Circuits

Electric charge in circuits explains how charged particles behave in matter and how current is produced. Everyday static effects, like a wool sweater sticking to the body or a shock from a carpet, show charge in action. Charge is an inherent property of atomic particles and is measured in coulombs (C). Matter is made of atoms with electrons, protons, and neutrons. Electrons carry a negative charge (-e), and protons carry a positive charge (+e). These two charges have the same magnitude. An...

voltage

Voltage in Electric Circuits

Voltage in electric circuits is the energy needed to move electric charge between two points. It is also called electromotive force, or EMF. In most circuits, an external force such as a battery provides this energy for electron movement in a conductor. The voltage between points a and b is written as v_ab. It is defined as the work, or energy, needed to move a unit charge from point a to point b. In the equation, w is the energy in joules and q is the charge in coulombs. Voltage is measured...

power and energy

Circuit Power, Absorption, and Supply

Circuit power, absorption, and supply explain how much energy an element uses or delivers in an electric circuit. These ideas matter in electrical engineering because power and energy calculations help describe circuit behavior. A 100-watt light bulb, for example, emits more light than a 60-watt bulb, so wattage is a useful measure in real devices. Power is the time rate of expending or absorbing energy. It is measured in watts, written as W. The relation between power and energy uses the...

electric circuit elements

Circuit Elements: Passive, Active, and Linear

Circuit elements are the building blocks of an electric circuit. An electric circuit is the connection of these elements. In this context, circuit elements are often grouped by how they behave and whether they supply energy. One major group is passive elements. These elements do not generate energy. Common passive elements include resistors, capacitors, and inductors. The other group is active elements, which can generate energy. Generators, batteries, and operational amplifiers are typical...

circuit terminology

Circuit Parts: Branches, Nodes, and Loops

Circuit parts like branches, nodes, loops, and meshes help describe how electrical networks work. An electrical network is a system of connected elements, such as resistors, capacitors, inductors, and voltage or current sources. Unlike a circuit, a network does not have to form a closed path. A circuit is also made of connected electrical elements, but it must include one or more closed paths. These loops let current flow continuously, which is what makes the circuit operate. Because of this,...

independent and dependent sources

Circuit Source Symbols and Controls

Circuit sources in electrical circuits can be independent or dependent. They provide the power a circuit needs to operate. Independent voltage sources supply a fixed voltage, and independent current sources supply a fixed current. Their output does not change because of other parts in the circuit. These sources use standard symbols in circuit diagrams. An independent voltage source is shown with + and - signs to mark the potential difference. An independent current source is shown with an...

ohm's law

Resistance and Conductance in Circuits

Resistance and conductance help explain how electric current moves through a circuit. Resistors are basic circuit parts made from metallic alloys or carbon compounds. They are used to model how a material resists current and to control and regulate electrical power in a circuit. Ohm's law describes the link between voltage and current across a resistor. The voltage across a resistor is directly proportional to the current through it. The constant that sets this relationship is resistance.

kirchhoff's current law

Kirchhoff's Current Law at Circuit Nodes

Kirchhoff's Current Law explains how current behaves at a circuit node. A node is the point where two or more circuit elements meet. The law says the current entering a node equals the current leaving it. That balance follows the rule of charge conservation, which means electric charge is not lost at the junction. When applying KCL, currents entering the node are treated as positive and currents leaving the node are treated as negative. The currents can be added algebraically at the node, and...

kirchhoff's voltage law

Voltage Balance in Closed Circuit Loops

Kirchhoff's Voltage Law explains how voltage is balanced in a closed circuit loop. It is a basic rule in electrical engineering and comes from the idea of energy conservation. Energy can change form, but it cannot be created or destroyed. KVL states that the algebraic sum of all voltages around a closed path, or loop, is zero. In other words, the total voltage supplied in a loop equals the total voltage drop across the components in that loop. A loop can be traced clockwise or anticlockwise,...

voltage dividers

Series Resistors and Voltage Split

Series resistors split voltage across a circuit. In a series setup, resistors are linked one after another. The same current flows through each resistor in the chain. To analyze this behavior, Ohm's law is used to relate voltage, current, and resistance. Kirchhoff's voltage law says the voltages around a series loop add up to the source voltage. That means the current in the circuit equals the source voltage divided by the total resistance in series. The current value can then be used in Ohm's...

current dividers

Parallel Resistors and Current Division

Parallel resistors share the same two nodes, so each resistor has the same voltage across it. In this circuit setup, Kirchhoff's current law applies. The source current equals the sum of the currents through each branch. Ohm's law helps find the branch currents from the source voltage and the resistor values. The source current is equal to the source voltage times the sum of the reciprocals of the resistances. This makes it easier to calculate how current divides in the circuit. The current...

equivalent resistance

Delta-Wye Network Conversion

Delta-wye network conversion helps analyze resistor circuits that are not arranged in simple series or parallel paths. These three-terminal equivalent networks use the wye (Y), also called tee (T), and the delta (Δ), also called pi (π), as practical circuit models. These networks are useful in many circuit settings. They appear in three-phase electrical systems, electrical filters, and matching networks. They can also be used on their own or combined with more complex circuits. A delta...

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

The Scientific Method

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Ask questions and define problems related to specialized topics of study based on observations or information from text, phenomena, models, or investigations;

112.51.c.1.A.

Scientific Method

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Observation and Background Research
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Problem Definition

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Apply science practices related to specialized topics of study to plan and conduct investigations or use engineering practices to design solutions to problems;

112.51.c.1.B.

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Use appropriate safety equipment and practices during laboratory, classroom, and field investigations as outlined in Texas Education Agency-approved safety standards;

112.51.c.1.C.

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112.51.c.1.D.

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Collect quantitative data using the International System of Units (SI) or qualitative data as evidence as appropriate to the specialized topic of study;

112.51.c.1.E.

Review and Preview

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What is a Frequency Distribution

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Histogram

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Relative Frequency Histogram

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Scatter Plot

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Time-Series Graph

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Bar Graph

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Multiple Bar Graph

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Pareto Chart

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Organize quantitative or qualitative data using representations appropriate to the specialized topic of study such as scatter plots, line graphs, bar graphs, charts, data tables, diagrams, scientific drawings, and student-prepared models;

112.51.c.1.F.

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112.51.c.1.G.

Scientific Laws and Theories

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Distinguish among scientific hypotheses, theories, and laws as appropriate to the specialized topic of study.

112.51.c.1.H.

Identify advantages and limitations of models such as their size, scale, properties, and materials as appropriate to the specialized topic of study;

112.51.c.2.A.

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Resistive Touchscreen Voltage Mapping

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