Touch-screen types and working principle of The basic principle is that touch-screen with fingers or other objects touch display installed in front of the touch screen when the touch location (in coordinate form) from the touch screen controller testing, and through the interface (such as the RS232 serial port) sent to the CPU to determine the information entered. Touch screen systems typically include touch-screen controller (card), and touch detection device in two parts. Among them, touch screen

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Nov 10, 2013 (4 years and 8 months ago)


screen types and working principle of

The basic principle is that touch
screen with fingers or other objects
touch display installed in front of the touch screen when the touch
location (in coordinate form) from the touch screen controller testing,
and through the interface (such as the RS232 serial port) sent to the
CPU to determine the information entered.

Touch screen systems typically include touch
screen controller (card),
and touch detection device in two parts. Among them, touch screen
ller (card)'s primary role is from the touch
point detection device
to receive touch information, and will convert it into a contact
coordinates, and then sent to CPU, it also can receive commands sent and
the CPU to be implemented: touch the test device i
s usually installed
on the display front, the main role is to detect a user's touch position,
and send it to the touch
screen control card.

1. Resistive touch screen (Resistive Touch Screen Working Principle

Resistive touch screen panel body par
t is a match with the display surface,
layer composite films by a layer of glass or plexiglass as a
roots level, the surface coated with a layer of transparent
conductive layer, above the outer surface and then covered with a layer
of hardened,

smooth anti

scraping the plastic layer, and its inner
surface is also coated with a layer of transparent conductive layer, in
between the two conductive layers there are many small (less than one
thousandth inch) transparent insulating isolation points
separated them.
When the finger touch screen, usually two mutually insulated conductive
layer on the touch point location has a contact, because one side
conductive layer connected to Y
axis direction 5V uniform voltage field,
making detection of the volta
ge level from zero into a non
zero, this
state is connected to the controller detected was conducted after the
A / D conversion, and will be 5V voltage value and touch points can be
obtained compared to Y
axis coordinate, empathy derived X
axis coordinate
This is all the resistive touch screen technology, the most basic
principles of the common. Resistive type touch screen is the key to
material science and technology. Resistance under the Lead
out of how
many screens were divided into four
lane, five, six,

and many other wire
resistive touch screen. Resistive Touch Screen in tempered glass surfaces
were coated with two layers of OTI transparent conductive metal oxide
layer, the outermost layer of OTI coating as conductive body, and the
second layer through
a sophisticated network of OTI is attached to if
they had two directions of +5 V to 0V

The voltage field, between the two OTI to small isolated spots separated
by a transparent. When the finger touch
screen, the two conductive layers
OTI will appear a poi
nt of contact, the computer at the same time detection
voltage and current to calculate the location of touch, the reaction speed
of 1020ms

. 5
wire resistive touch screen outer conductive layer using a nickel
coating materials a good ductility, oute
r conductive layer due to the
frequent touch, use a good ductility Ni
Au material intended to extend
the service life, but the cost of more expensive technology. Although
the ductility Ni
Au conductive layer is good, but only as a transparent
conductor, is

not suitable as a resistive touch
screen face, because it
is a high conductivity, but also very uniform thickness of metal is not
easy to do, are not suitable for voltage distribution layer, only serve
as a probe layer.

Resistive touch screen is a comple
tely isolated from the outside world
working environment, not afraid of dust and water vapor, which can be
used to touch any object that can be used to write to draw, more suitable
for industrial control and office area of the limited human use. Resistive
touch screen because of the common drawback is that the outer layer of
composite films using plastic materials, people who do not know too much
force or use of sharp touch may scratch a result of scrapping the entire
touch screen. However, within the limit
s, cuts will hurt outer conductive
layer, outer conductive layer of scratch for the five
wire resistive touch
screen is no relationship, while the four
wire resistive touch screen
is fatal.

2. Capacitive touch screen technology:

Is to use current sensing

for the human body works. Capacitive touch screen
is a piece of four
layer composite glass screen, glass screen and the
mezzanine of the inner surface coated with a layer of ITO, the outermost
layer is a thin layer of silica glass protective layer, lamina
ted ITO
coated as a face, the four corners of the leads to four electrodes, the
inner layer of ITO as a shield in order to ensure a good working environment.
When the fingers touch the metal layer when the electric field due to
the human body, users, and t
screen surface with a coupling capacitor
for the high
frequency current, the capacitor is a direct conductor, so
from the point of contact fingers sucked a small current. The current
screen from the four corners of points on the electrodes in th
outflow, and the current flowing through the four electrodes and the
finger is proportional to the square of the distance from the controller
through the exact proportion of these four current calculations, touch
points position. Capacitive touch screen

■ For most environmental pollutants are resistance.

■ the human body to become a part of the line, so drift is relatively

■ does not work with gloves.

■ require constant calibration.

■ does not apply to metal cabinets.

■ When the o
utside world when the inductance and magnetic induction will
lead to failure of touch screen.

3. Infrared Touch Screen (Infrared Touch Screen working principle diagram)

Infrared touch screen is to use X, Y direction of the infrared dense matrix
to detect

and locate the user's touch. Infrared touch screen in front
of the monitor frame to install a circuit board, circuit board on the
screen Quad
arranged IR LED and infrared receiver tube, one
correspondence to form if they had cross
infrared matrix. When us
ers touch
the screen, the finger will be blocked if they had been the location of
the two infra
red, so you can determine the location of touch points on
the screen. Any object can change the contact on the touch infra
screen operation achieved.
Infrared touch screen is not current,
voltage and electrostatic interference, suitable for harsh environmental
conditions, infrared technology is the ultimate touch
screen product
trends. Use of acoustic and other touch
screen technology, materials

has its own insurmountable barriers, such as single sensor damaged,
aging, touch interface, afraid of contamination, destructive use,
maintenance complex and so on. Infrared touch screen as long as the truly
high stable performance and high resolution is
bound to substitute other
screen technology products and become mainstream. The past,
infrared touch screen resolution from within the framework determined
by the number of IR on the possession, so lower resolution, the market's
main domestic product

32x32, 40X32, in addition to light, said infrared
screen environmental
factors rather sensitive to changes in light when the miscarriage of
justice or even a larger machine. These are

Infrared touch screen is a foreign non
domestic sales promotion agent
of infrared screen weaknesses. The latest technology, the
generation infrared screen resolution depends on the

Infrared Emitting Diode and the number of scan frequency and difference
algorithms, the resolution has reached 1000X720, As for the infr
screen in the lighting conditions, instability,

From the second
generation infrared touch screen started, it has good
resistance to light interference to overcome this weakness. The
generation infrared touch screen is a whole new generation of

Energy technology products, which implements the 1000 * 720
resolution, multi
level self
regulation and self
healing ability
to adapt the hardware and highly intelligent judge knowledge

Do not be a long time in the arbitrary use of a va
riety of harsh environments.
And can be extended for custom features, such as network control, acoustic
sensing, human access

Near sensors, the user software encryption protection, infrared data
transmission. The original media of infrared touch screen An
other major
drawback is that the violence, poor

In fact, infrared screen can use any customer to the satisfaction of the
riot of glass without increasing the cost and impact of the use of too
much performance, it is the other

The touch
screen that can no
t be replicated.

4. Surface acoustic wave touch screen (surface acoustic wave touch screen
works diagram)

To the lower right corner of the X

Axis emission transducers, for example: the launch transducer touchscreen
controller cable to the electrical sig
nal into sound waves sent to

The amount of the surface of the left side pass, and then by the glass
bottom of a group of sophisticated acoustic energy reflective stripes
to a uniform reflective surface upward into the transmission, sound waves
can be

er the amount of screen surface, and then the reflection from the upper
right of the line, forming stripes transmitted to X

Axis receiver transducer, the receiver will return to the transducer

Acoustic energy into electrical signals. When transmi
tting transducer
launches a narrow pulse, the acoustic energy in different ways to reach
the receiver after transducer and take the rightmost

While the earliest arrival, take the left
most of the last to arrive,
early arrival and late arrival of these sou
nd waves into a wider energy
superimposed waveform signal, not

Difficult to see a collection of the received signal in the X
direction of all the different paths after the return of the length of
acoustic energy, they are Y
axis relative to the dista
nce traversed

The same, but in the X
axis, furthest away more than twice the recent
axis maximum distance. Therefore, this waveform signal timeline reflect
the original wave

Shaped pre
stack position, that is, X
axis coordinate. Emission signal
and the

received signal waveforms in the absence of touch when the received
signal waveform with the reference

According to the waveform exactly the same. When a finger or other be
able to absorb or block the energy of the object wave touch screen, X
g through the fingers go up site

Acoustic energy is partially absorbed, the reaction on the waveform at
the receiver position at some point that there is an attenuation of wave
gap. Received waveform corresponding to a finger block

Parts of the signal at
tenuation of a gap here that the calculation of
the gap analysis to get touch coordinates controller receives the signal
attenuation determined by the location of the gap

X coordinate. After the Y
axis out of the same process to

determine the
Y coordinates of touch points. In addition to the general touch screen
can respond to the X, Y coordinates, the surface acoustic

Wave touch screen also responded to third
axis Z
axis coordinate, which
is capable of sensing the user touch
essure size. The principle is that
signal attenuation by the receiving Office, the attenuation

The amount calculated. Triaxial Once identified, put them to the host