Transcript PPT

BY:
GAURAV P. YEOTKAR
(final year BE information technology)
GUIDED BY:
Prof. N. S. KHACHANE
Department of CSE
TOUCH SCREEN: A touch screen is a display which can detect the
presence and location of a touch within the
display area. It allows you to interact with the
display using your finger, or by touching stylus of
anything else
TECHNOLOGIES:-
Resistive:
1. Composed of several layers.
2. The most important are two thin metallic electrically
conductive and resistive layer separated by thin space.
Surface acoustic wave:
1. SAW technology uses ultrasonic waves that pass over the
touch screen panel .
2. When touched a portion of wave is absorbed.
3. This change registers position of touch and sends it to
controller.
Capacitive:
1. Touch panel is coated with material like indium tin oxide that
conducts the continuous electrical current across the sensor.
2. Therefore sensor exhibits capacitance.
3. The human body also has stored electron thus it also exhibits
capacitance.
4. When the sensor’s normal capacitance is altered by another
capacitance, the electronic circuit at corner of the panel
measures the resultant distortion.
Infrared:
1. An IR touch panel employs 2 ways.
a) Thermal induced changes of surface resistance.
b) Array of horizontal and vertical IR sensors that detect the
interruption of modulated light beam
Optical imaging:
1. Two or more image sensors around the edge of panel.
2. IR backlights are placed in camera’s field of view on the other
side of screen
3. A touch shows up a shadow and each pair of camera can
then be triangulated to locate the touch
Dispersive signal technology:
1. Uses sensors to detect the mechanical energy in the glass that
occur due to touch.
2. Complex algorithms then interprets the information and
provides actual location of the touch
DEVELOPMENT:
1. The touch screens are then developed to multipoint touch
screen.
2. Facilitated the tracking of more than one finger on screen.
these also allows multiple users to interact with single screen
1. Multitouch is a human computer interaction technique
and the hardware device that implement it.
2. Multitouch consists of touch screen like screen, table, wall
or touchpad, as well as software that recognize multiple
simultaneous touch points
3. This effect is achieved by variety of means like heat, finger
pressure, high capture rate cameras, infrared light, optic
capture, tuned EM induction and shadow capture etc
HISTORY:
Bell labs:
1. in 1984 Bell Labs engineered a multitouch screen that could
manipulate images with more than one hand
2. In 1991 Mr. Pierre Wellner published paper on his multi touch
digital desk which supported pinching motion with multi fingers
Fingerworks:
1. In 1998 FW produced a line of multitouch products.
2. In 2005 Fingerworks was acquired by apple computer.
PRINCIPLES:
1. TIR (total internal reflection) is an optical phenomenon that
occurs when a ray of light strikes a medium boundary at an
angle larger than the critical angle with respect to the
normal to the surface
2. Critical angle and TIR are illustrated by figure given below
3. Critical angle is given by formula
DESIGN:
ACRYLIC WITH LED’S AT ITS EDGES
Table with camera and projector
FTIR WORKING
IR RAYS OBTAINED ON CAMERA
IR view of a touch
Pixel positions located on screen
1. Multi touch based on FTIR is a simple and inexpensive technique .It
constructs a multi touch display with the available and less costly
materials.
2. Scalable technique that enables high-resolution graphics .It
provides support to any resolution possible as all multiple points
could be generated on a camera
3. It acquires true touch image information at high spatial and
temporal resolutions. The actual finger print of the touch is
obtained .This could be used to determine the force sensitivity on
displays; either too hard or soft touches can be analyzed.
4. It is scalable to large installations. Any kind of applications can be
made to suit multi touch using FTIR. Allows us to create
sophisticated multi-point widgets for applications
5. Larger shared-display systems i.e. it is well suited for use with rear
projection like wall screens, table tops .All this lead to high
resolution graphics.
1. Personal computers, Laptops, Tabletops, Graphics Tablets.
2. It supports both LCD and CRT monitors.
3. Telephones, Watches, PDAs, Mobile phones.
4. Advanced multi touch Gaming with high graphics support.
5. Governmental, office and business purposes.
6. An enhanced multimedia experience including audio, video and
photo sharing.
7. Enhanced dining experience.
Microsoft Surface turns an ordinary tabletop into a vibrant, interactive
computing experience. The product provides effortless interaction
with digital content through natural gestures, touch and physical
objects. In Essence, it’s a surface that comes to life for exploring,
learning, sharing, creating, buying and much more. Currently
available in selected restaurants, hotels, retail establishments and
public entertainment venues, this experience will transform the way
people shop, dine, entertain and live. Surface is a 30inch display in a
table like form factor that’s easy for individuals or small groups to
interact with in a way that feels familiar, just like in the real world.
1. Touch screens are the interface for the 21st century.
2. These devices have limited resolution, are relatively complex, and
don't easily and inexpensively scale up to large dimensions.
3. Multi-touch technologies have a long history. This technique using
FTIR is simple and easy to implement.
4. It provides any resolution displays supported with high graphics .
5. The applications being both made and proposed are plenty in
number.
6. A drawback of the approach is that, being camera-based; it
requires a significant amount of space behind the interaction
surface, though we primarily expect application scenarios where
rear-projection would have been employed anyway (e.g.
interactive walls, tables). Also, as an optical system, it remains
susceptible to harsh lighting environments.
1. Jefferson Y. Han Low-Cost Multi-Touch Sensing through FTIR.
2. Buxton, W., Hill, R., and Rowley, P. 1985. Issues and Techniques in TouchSensitive Tablet Input.
3. Donald Hearn, M Pauline Baker, Computer Graphics C version, 2/E
Pearson Education, 2003.
4. Buxton, Bill. 2008. Multi-Touch Systems that I Have Known and Loved.
http://www.billbuxton.com/multitouchOverview.html.
5. by Harry Vaan Der’ How to build a multi touch Open source, Multitouch
Display, http://www.technologyreview.com/Infotech.
6. http://www.surface.com.
7. http://www.perceptivepixel.com.
8. http://www.apple.com/iphone/.
9. Allison Jeffers Gainey [email protected] November 2008 EDUC 651
http://www.techcrunch.com/2007/05/29/microsoft-announces-surface
computer.