enjoy the slide ..

1. Speech Oriented Devices
And Touch Panels

2. What is touch screen??
A touchscreen is an electronic visual
display that can detect the presence
and location of a touch within the
display area

3. Touch Panels
How does a touch screen work???
A basic touch screen has three main
components:
1 Touch sensor;
2 Controller;
3 Software driver.
The touch screen is an input device, so
it needs to be combined with a display
and a PC or other device to make a
complete touch input system

4. Touch panels
 A touch screen sensor is a clear glass
panel with a touch responsive surface. The
touch sensor/panel is placed over a display
screen so that the responsive area of the
panel covers the viewable area of the video
screen.

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

6. Touch Screen Technology
 Resistive touch screen
 Capacitive touch screen
 Infrared touch screen
 Surface acoustic wave (SAW) touch
screen
 Strain gauge touch screen
 Optical imaging touch screen
 Dispersive signal technology touch
screen

7. RESISTIVE TOUCH SCREEN
 The resistive system consists of a normal glass
panel that is covered with a conductive and a
resistive metallic layer. These two layers are held
apart by spacers, and a scratch-resistant layer is
placed on top of the whole setup.
 An electrical current runs through the two layers
while the monitor is operational. When a user
touches the screen, the two layers make contact in
that exact spot.
 The change in the electrical field is noted and the
coordinates of the point of contact are calculated
by the computer.
 Once the coordinates are known, a special driver
translates the touch into something that
the operating system can understand, much as a
computer mouse driver translates a mouse's
movements into a click or a drag.

9. Capacitive Screen
 In the capacitive system, a layer that stores
electrical charge is placed on the glass panel of
the monitor.
 When a user touches the monitor with his or her
finger, some of the charge is transferred to the
user, so the charge on the capacitive layer
decreases. This decrease is measured
in circuits located at each corner of the monitor.
 The computer calculates, from the relative
differences in charge at each corner, exactly where
the touch event took place and then relays that
information to the touch-screen driver software.

11. Resistive vs capacitive
Technology Resistive Capacitive
Transparency 75-85% Very good>92%
Resolution Good Good
Surface Unaffected by Surface Resistance to
contaminants/durabilit contaminants. Polyester moisture and other
y top sheet is easily surface contaminants
scratched
Sensor substrate Polyester top sheet, glass Glass with ITO coating
substrate with ITO
coating
Display size Up to 19” 8.4 -21”
Touch method Can use any pointed Human touch
device

12. Speech Oriented Devices-
an automated system.

13. Categeries:
 Small-vocabulary/many-users
These systems are ideal for
automated telephone answering. The
users can speak with a great deal of
variation in accent and speech
patterns, and the system will still
understand them most of the time.

14. Large-vocabulary/limited-
users
These systems work with a good
degree of accuracy (85 percent or
higher with an expert user) and have
vocabularies in the tens of thousands.

15. Conversion of speech to on-
screen text or a computer
command:

16. Flow chart:

speech

vibration in the air
Analog to
digital
convertor
(ADC)
translate
Digital data

17. The system filters the digitized sound
to remove unwanted noise, and
sometimes to separate it into different
bands of frequency.
 It also normalizes the sound, or
adjusts it to a constant volume level

18.  Next the signal is divided into small
segments as short as a few
hundredths of a second, or even
thousandths in the case of plosive
consonant sounds -- consonant
stops produced by obstructing airflow
in the vocal tract -- like "p" or "t." The
program then matches these
segments to known phonemes in the
appropriate language. A phoneme is
the smallest element of a language

20. The program examines phonemes in
the context of the other phonemes
around them. It runs the contextual
phoneme plot through a complex
statistical model and compares them
to a large library of known words,
phrases and sentences
output
as text or as a computer
command.

21. Weaknesses and Flaws:
 Low signal-to-noise ratio(quality of
sound)
 Overlapping speech
 Intensive use of computer power
(requires the computer's processor
to do a lot of heavy work)
 Homonyms (have different
meanings but sound the same.)