VS20UA CONTROLLER

Supply Voltage

5.0V DC

Maximum Current

20mA (Pick)

Resolution

12-bit

A SEMINAR REPORT

ON

TOUCH SCREEN

DEWAN V.S. INSTITUTE OF ENGINEERING

& TECHNOLOGY , MEERUT

Submitted To: Submitted By: Er. Priyanka Gupta Siddharth PanghalElectronic department EC Engg.(6th sem)

DATE OF SUBMISSION

14th JUNE2011

Pros

Direct pointing to the objects.

Fast

Finger or pen is usable (No cable required)

No keyboard necessary

Suited to: novices, application for information retrieval etc

Cons

Low precision by using finger

User has to sit or stand closer to the screen

The screen may be covered more by using hand

No direct activation to the selected function

APPLICATIONS..

Public Information Displays:::

Tourism displays, Trade show display

Customer Self-Services:::

Stores, Restaurants, ATMs, Airline ticket terminals and Transportation hubs.

More uses...

Digital jukeboxes, Computerized gaming, Student Registration systems, Multimedia softwares , Scientific applications etc.

Though the touch screen technology contains some limitations it’s very user friendly, fast, accurate, easy for the novices & fun to operate. It has been widely accepted. And now by just modifying a little it can replace the mouse and key board completely in near future.

Projected Capacitive Touch screen

3layers:-front and back protective glass provides optical and strength enhancement options & middle layer consists of alaminated sensor grid of micro-fine wires.

During a touch, capacitance forms between the finger and the sensor grid.

The embedded serial controller in the touch screen calculates touch location coordinates and transmits them to the computer for processing.

SURFACE WAVE TECHNOLOGY

It has a transmitting and receiving transducers for both the X and Y axes.

The touchscreen controller sends a 5 MHz electrical signal to the transmitting transducer, which converts the signal into ultrasonic waves within the glass.

These waves are directed across the front surface of the touchscreen by an array of reflectors.

Reflectors on the opposite side gather and direct the waves to the receiving transducer, which reconverts them into an electrical signal—a digital map of the touchscreen

When you touch the screen, you absorb a portion of the wave traveling across it. The received signal is then compared to the stored digital map, the change recognized, and a coordinate calculated. . The digitized coordinates are transmitted to the computer for processing.

Compared to Resistive and Capacitive technologies, SAW technology provides superior image clarity, resolution, and higher light transmission. Because the panel is all glass, there are no layers that can be worn, giving this technology the highest durability factor and also the highest clarity.

RESISTIVE TOUCH SCREEN

1. Polyester Film .

2. Top Resistive Layer.

3. Conductive Transparent Metal Coating.

4. Bottom Resistive Layer .

5. Insulating Dots .

6. Glass Substrate

Resistive touch screen monitor is composed of a flexible top layer and a rigid bottom layer separated by insulating dots, attached to a touch screen controller.

The inside surface of each of the two layers is coated with a transparent metal oxide coating

Pressing the flexible top sheet creates electrical contact between the resistive layers, producing a switch closing in the circuit.

The controller gets the alternating voltages between the two layers and converts them into the digital X and Y coordinates of the activated area.

Resistive touch panels are made of two sheets of conductive material. This conductive material needs to be uniformly coated on both sides. When you press a resistive panel, one side smushes into the other side.

TOUCH SCREEN DIVERSITY

Resistive Touch screen

Surface wave Touch screen

Capacitive Touch screen

Surface capacitive Projected capacitive

Near Field Imaging Touch screen

Infrared Touch screen

SOFTWARE DRIVER

The driver is a software that allows the touch screen and computer to work together. It tells the operating system how to interpret the touch event information that is sent from the controller.

Most touch screen drivers today are a mouse-emulation type driver. This makes touching the screen the same as clicking your mouse at the same location on the screen.

Touch sensing helps increase product lifetimes by eliminating the mechanical wear and tear associated with push buttons and switches. The Xtrinsic Touch Sensing Software (TSS) 2.5 now enables touch sensing in any ColdFire+ and Kinetis MCUs in addition to all of Freescale's 8-bit S08 or 32-bit V1.

It’s a snowy night, and you’re about to use the ATM outside your local grocery store that’s been there for years. You enter in your access code, and notice only 2 of the 4 entries are reflected on the display.

CONTROLLER

The controller is a small PC card that connects between the touch sensor and the PC. It takes information from the touch sensor and translates it into information that PC can understand.

Technical Editor Robert Cravotta explores processor and software-processing architectures and the impact they have on system and software development. Relevant architectures include microprocessors, microcontrollers, digital signal processors (DSPs), multiprocessor architectures, processor fabrics, coprocessors, and accelerators, plus embedded cores in FPGAs, SOCs, and ASICs

. The humidity and the temperature of the environment also affects the wear and

tear seen by the resistive panel. The air trapped inside the resistive panel is maintained by adding a layer, often called spacer dots, between the flex and the stable

While there are coatings and heaters and special manufacturing precautions to add to the longevity of the sensor, the sensor will eventually succumb to wear and tear and stop functioning. It’s up to the touch controller to be designed with a wide window of operation so that it will continue to function for as long as possible.

TOUCH SENSOR

A touch screen sensor is a clear glass panel with a touch responsive surface which is placed over a display screen so that the responsive area of the panel covers the viewable area of the display screen.

The sensor generally has an electrical current or signal going through it and touching the screen causes a voltage or signal change. This voltage change is used to determine the location of the touch to the screen

TouchSensor Technologies designs and manufactures patented digital switches for use in touch-sensitive User Interface Panels. Much more durable than mechanical and membrane switches, TouchSensor keypads have become the new standard for solid-state switching.

Resistive touch panels are made of two sheets of conductive material. This conductive material needs to be uniformly coated on both sides. When you press a resistive panel, one side smushes into the other side

WHAT IS TO BE EXPLAINED..

INTRODUCTION TO THE TECHNOLOGY

HOW IT WORKS ?

TOUCH SCREEN DIVERSITY

CONTROLERS USED

APPLICATIONS

CLOSING THOUGHTS

HOW DOES A TOUCHSCREEN WORK?

Main touch screen components:

Touch sensor

Controller

Software driver

CERTIFICATE

This to certify that the presentation report entitled Touchscreen Technology by Siddharth Panghal roll no. 0831131035 is carried out by him under my supervision. The matter embodied in this presentation report has not been submitted earlier for award of any degree or diploma in any university/institution to the best of our knowledge & belief.

Project Guide

Er. Priyanka Gupta

ACKNOWLEDGEMENT

I take immense pleasure in thanking Brig. V.P Munjal our honrable Director, for having permitted me to carry out this project work.

I wish to express my deep sense of gratitude to my internal guide Er. Priyanka for her able guidance & useful suggestions, which helped me in completing the project work in time.

Finally, yet important, I would like to express my heartfeltthanks to my beloved parents for their help & wish for the Successful completion of this project.

CAPACITIVE TOUCH SCREENS

Surface Capacitive

It has a an uniform conductive coating on a glass panel.

During operation, electrodes around the panel's edge evenly distribute a low voltage across the conductive layer & creates an uniform electric field.

A finger touch draws current from each corner.

Then the controller measures the ratio of the current flow from the corners and calculates the touch location

The fact that your blood cells are capacitively coupled to one another is actually the basis for capacitive touch. Because your blood cells can form capacitors, it means that every surface of your body is capacitively coupled to every other surface.

when you touch a button on your cap touch microwave oven, you are basically capacitively coupling the button to the cabinet of the microwave through your body, and potentially some of the floor, walls, and other objects in the vicinity.

The basic equation for capacitance is C = eoerA/D, where C is capacitance in Farads, eo is the permittivity of free space, er is the relative permittivity of the insulator between the plates, A is the area of the smaller plate, and D is the distance between the plates.