Touchscreens has been part of every technology that we use in recent time, examples of which can be seen in the smartwatch or it the smartphones also we have been introduced to the touchscreens in the laptop. So getting to know how it works is a question of curiosity and we will be trying to provide the answers to those question here. Before we go towards the functioning of lets see when and how we got to know about these technology.
History of Touchscreen’s
Touchscreens is not just the recent technology that we see today it has been since a long time. The first touchscreen was seen in 1965 which was known as the finger driven screen and could support only one finger touch at a time.
It become available only after 1970, where the first type of touchscreen known as the Resistive touchscreen which we can say was developed accidentally while performing an experiment. The development of multi touch display become evident in the 1980s. we could see the first touchscreen cellphone in the 90s
Touchscreen and its type’s
Basically the type of touchscreen which we use commanly is divided into two types which are:-
- Resistive Touchscreen
- Capacitive Touchscreen
Resistive Touchscreen
Resistive touchscreens work on the basis of pressure applied to the screen. A resistive screen consists of a number of layers. When the screen is pressed, the outer later is pushed onto the next layer — the technology senses that pressure is being applied and registers input.
A resistive touch screen consists of top and bottom transparent sheets facing each other with a gap between them. The top and bottom sheets are coated with ITO (Indium Tin Oxide). ITO is a transparent conducting material. The top and bottom sheets have uniform resistance value over its surface.
As the top sheet gets pressed, the pressed point of the top sheet physically yields and contacts the bottom sheet. As the Indium Tin Oxide layers of the top and bottom sheets contact, electricity gets conducted at the contacted point, and the location of the conducted point is detected.
Capacitive Touchscreen
As opposed to the resistive touchscreen, which relies on the mechanical pressure made by the finger or stylus, the capacitive touchscreen makes use of the fact that the human body is naturally conductive. Capacitive screens are made of a transparent, conductive material usually ITO coated onto a glass material we have seen about the Indium Tin Oxide(ITO) in the resistive touchscreen above. It’s the glass material that you touch with your finger.
Unlike a Resistive Touchscreen, some capacitive touchscreens cannot be used to detect a finger through electrically insulating material, such as gloves. This disadvantage especially affects usability in consumer electronics, such as touch tablet PCs and capacitive smartphones in cold weather when people may be wearing gloves.
t can be overcome with a special capacitive stylus, or a special-application glove with an embroidered patch of conductive thread allowing electrical contact with the user’s fingertip. Some capacitive display manufacturers continue to develop thinner and more accurate touchscreens. Those for mobile devices are now being produced with ‘in-cell’ technology.
Mobile Touchscreen
The touchscreen of the smartphones uses the three layer mechanism to provide seamless scrolling over the mobile screen. The three layer which we are talking about is discussed as:-
- chemically Toughened glass
- protected capacitive Touchscreen
- Lcd Dislplay
Chemically Toughened glass
Chemically strengthened glass is a type of glass that has increased strength as a result of a post-production chemical process. Chemical strengthening is the name given to glass products that have been strengthened by means of an ion-exchange process. It is a surface treatment which occurs at a temperature lower than glass melting temperature
These potassium ions are larger than the sodium ions and therefore wedge into the gaps left by the smaller sodium ions when they migrate to the potassium nitrate solution. This replacement of ions causes the surface of the glass to be in a state of compression and the core in compensating tension.
Projected capacitive touchscreen
Projected capacitive touch technology is a variant of capacitive touch technology but where sensitivity to touch, accuracy, resolution and speed of touch have been greatly improved by the use of a simple form of “Artificial Intelligence”. This intelligent processing enables finger sensing to be projected, accurately and reliably, through very thick glass and even double glazing.
Projected capacitive touchscreens consist of a charged matrix, or field, of columns and rows that are read or scanned by the microcontroller. When a finger or stylus interacts with the screen, the microcontroller can “read” the touch point because of “mutual capacitance.” Mutual capacitance posits that conductive objects will hold a charge when they are in close proximity to each other.
LCD Display
LCD (Liquid Crystal Display) is a type of flat panel display which uses liquid crystals in its primary form of operation. Liquid crystals do not emit light directly, instead use a backlight or reflector to produce images in color or monocrome(A monochromatic object or image reflects colors in shades of limited colors or hues).
CDs were a big leap in terms of the technology they replaced, which include light-emitting diode (LED) and gas-plasma displays. LCD allowed displays to be much thinner than cathode ray tube (CRT) technology. LCD consume much less power than LED and gas-display displays because they work on the principle of blocking light rather than emitting it. Where an LED emits light, the liquid crystals in an LCD produces an image using a backlight.
ALL the layer in the combine form can be seen in this picture:
So after going through this topic you would know the basic’s of the Touchscreen, also we have learned of the intermediate concepts which strengthened our knowledge, but as we say that there plenty to learn yet one can also go through the advance and modern touchscreen which are -:-
- Infrared Touchscreen
- Surface Acoustic wave Touchscreen
- Near field Imaging
Brainstorm 