Perbedaan Layar Kapasitif dan Resistif Pada Handphone Touchscreen

Para pengguna ponsel pintar saat ini tahu bahwa handphone touchscreen di bagi menjadi dua jenis, yakni kapasitif dan resistif. Kedua jenis handphone touchscreen ini bisa ditemukan pada beberapa smartphone dan tablet yang mana dengan teknologi ini daftar menu yang terdapat pada ponsel maupun tablet akan merespon dengan cepat meskipun hanya dengan sentuhan yang kecil sekalipun yang memungkinkan fitur multi-touch bekerja dan pada umumnya sangat responsif terkecuali ketika Anda menggunakan sarung tangan. Namun ada beberapa perangkat yang mana meskipun disentuh dengan sentuhan kecil sekalipun mereka tidak bekerja, namun harus dengan sentuhan yang keras barulah menu atau aplikasi yang terdapat pada ponsel Anda dapat merespon dengan baik.

Apakah dari sebagian Anda tahu perbedaan di antara kedua jenis layar sentuh ini? Anda mungkin pernah merasakan perbedaan itu sendiri. Ketika itu terjadi, mungkin Anda bertanya-tanya, mengapa iPhone Anda tidak bekerja saat Anda mengenakan sarung tangan? Mengapa layar sentuh pada feature phones berbeda dengan high-end phones? Mengapa Anda tidak bisa menggunakan semua stylus pen pada iPad Anda?

Ke semua pertanyaan itu bisa dijawab hanya dengan dua jawaban yaitu kapasitif dan resistif. Perbedaan teknologi layar sentuh ini akan menjawab semua pertanyaan Anda di atas.

Touchscreen dalam Hematnya

Meskipun teknologi touchscreen atau layar sentuh pada gadget dewasa ini berkembang secara pesat, bukan berarti bahwa teknologi kaca sentuh ini merupakan penemuan baru. Jika ditarik kebelakang, teknologi kaca sentuh ini pertama kali diketemukan pada tahun 1960 dan telah melalui beberapa perubahan dan iterasi hingga menjadi layar sentuh yang saat ini kita gunakan.

Layar sentuh tidak hanya terbatas penggunaannya pada smartphone dan tablet saja, mereka teraplikasikan di mana-mana, di mesin ATM, papan informasi, sistem navigasi, game konsol dan bahkan touchpad/ laptop. Layar sentuh saat ini muncul di mana-mana dan mengambil peranan penting dalam kehidupan kita, sehingga setidaknya yang bisa dilakukan adalah tahu lebih banyak tentang bagaimana teknologi kaca sentuh ini bekerja.

Resistive Touchscreen

Layar sentuh yang memiliki jenis resistif merupakan tipe layar sentuh yang paling umum. Kecuali untuk smartphone modern, tablet dan trackpad, layar sentuh yang paling umum ada adalah layar sentuh resistif. Seperti namanya, layar sentuh resistif ini mengandalkan gaya tahan (resisitive sendiri diambil dari nama resistance), dari pengertian ini bisa diketahui bahwa cara kerja dari layar sentuh berjenis resistif ini adalah berdasarkan gaya tahan atau tekanan yang mana layar memberikan respon ketika Anda berikan gaya tahan atau ketukan.

Layar sentuh resistif sendiri terdiri dari dua lapisan tipis yang dipisahkan oleh celah yang tipis. Pada ulasan ini tidak akan dibahas tentang lapisan tipis yang berada pada layar resisitif ini, namun kita akan fokus pada layar ini secara sederhana agar tidak membingungkan. Kedua lapisan ini memiliki lapisan di satu sisinya yang saling beradapan di dalam celah tersebut, jika digambarkan, lapisan pada kaca sentuh ini memiliki susunan seperti sandwich. Bila kedua lapisan ini saling bersentuhan, maka aliran listrik akan berlalu, dan yang pada gilirannya diproses sebagai sentuhan di lokasi tersebut.

Jadi ketika jari Anda, stylus atau perangkat lain yang mampu mendukung layar sentuh resistif, ini membuat sedikit tekanan pada lapisan atas, yang kemudian ditransfer ke lapisan yang berdekatan sehingga dimulainya sinyal kaskade. Karena inilah Anda dapat menggunakan apapun yang Anda mau untuk membuat sentuhan pada layar antarmuka, sarung tangan, batang kayu, kuku atau apapun yang menciptakan tekanan yang cukup akan direspon dengan baik oleh layar ini.

Untuk alasan yang sama, layar sentuh resistif ini membutuhkan sedikit tekanan untuk memproses sentuhan dan tidak selalu merespon dengan cepat seperti yang dilakukan oleh iPhone. Selain itu, beberapa lapisan pada layar resistif ini dapat mengakibatkan layar menjadi kurang tajam dengan kontras yang lebih rendah dari yang dilihat pada layar capacitive. Sementara itu, kebanyakan layar resistif paling tidak memungkinkan untuk melakukan gerakan multi-touch seperti pinch to zoom, layar ini baru bisa merespon gerakan zoom ketika Anda menyentuhkan satu jari yang di mana jari lainnya menyentuh lokasi yang berbeda pada layar.

Layar resisitif telah memperbaharui sistemnya secara bertahun-tahun, dan dewasa ini banyak ponsel pada kelas lower-end juga mengaplikasikan layar sentuh resistif ke dalam ponselnya yang mana masih kalah akurat dengan ponsel dengan kelas high-end. Beberapa ponsel yang terkenal telah mengusung layar ini adalah Nokia N97 dan N800. Sementara itu Nintendo DS menjadi game konsol pertama yang membawa layar ini untuk aktifitas gaming.

Capacitive Touchsreen

Jika ditarik ulur kebelakang, layar sentuh berjenis kapasitif ini ditemukan lebih pertama dibandingkan dengan layar resistif, layar sentuh kapasitif pertama dibuat 10 tahun lebih awal dibandingkan dengan layar sentuh resistif. Namun demikian, layar sentuh kapasitif saat ini lebih akurat dan merespon langsung ketika bersentuhan dengan jari manusia. Jadi bagaiman kerja dari layar sentuh kapastif ini?

Berbeda dengan layar sentuh resistif yang bergantung pada tekanan mekanis yang dibuat oleh jari atau stylus, layar kapasitif ini justru menggunakan sifat listrik dari manusia. Layar kapasitif biasanya terbuat dari satu lapisan isolasi, seperti kaca yang dilapisi dengan bahan konduktif transparan di dalamnya. Karena tubuh manusia adalah konduktif yang berarti aliran listrik dapat melewati tubuh manusia, layar kapasitif ini dapat menggunakan konduktivitas ini sebagai input atau masukkan. Ketika Anda menyentuh layar capacitive dengan jari Anda, akan menyebabkan perubahan medan listrik pada layar.

Perubahan ini dikenali, dan lokasi di mana Anda menyentuh bidang layar tersebut akan ditentukan oleh prosesor. Hal ini dapat dilakukan dengan teknologi yang berbeda, namun mereka semua tergantung pada perubahan elektrikal yang disebabkan oleh sentuhan dari jari manusia. Ini adalah alasan Anda tidak dapat menggunakan layar capacitive saat sedang menggunakan sarung tangan –sarung tangan tidak konduktif, dan sentuhan yang menggunakan sarung tangan tidak menimbulkan perubahan elektrik. Hal yang sama berlaku pada layar non kapasitif stylus.

Sejak layar ini terbuat dari satu lapisan utama yang terus-menerus dibuat semakin tipis karena kemajuan teknologi, layar ini tidak hanya lebih sensitif dan akurat, tampilan yang ditawarkannya pun bisa jauh lebih tajam seperti yang terlihat pada perangkat iPhone 4S. Dan tentu saja layar kapasitif ini dapat membuat multi-touch gestures yang berarti Anda dapat menggunakan beberapa jari Anda pada saat yang sama.

Sumber : http://m.portal.paseban.com/?mod=content&act=read&id=10312

Keuntungan dan Kerugian Touch Screen

Keuntungan menggunakan Touch Screen

1. Penggunaan mudah serta tidak terlalu banyak pelatihan pengguna dalam pengoperasioan layar sentuh.
2. Adanya kemampuan untuk memasukkan dan mengawasi data secara cepat.
3. Terdapat kontrol dan interaksi langsung antara indera penglihatan dan indera peraba masukkan dan keluaran yang dihasilkan terdapat pada satu lokasi yang sama.
4. Hanya pilihan yang valid dan mungkin untuk diterima yang dapat ditampilkan.
5. Mudah diterima oleh penggunanya.
6. Tidak dibutuhkannya daya ingat penggunanya.

Kerugian Touch Screen

1. Besarnya biaya pengembangan sistem layar sentuh sebagai teknologi yang belum lama digunakan dalam barang-barang yang diproduksi secara massal.
2. Membutuhkan tambahan waktu dalam proses pemrogramannya.
3. Kurang fleksibel untuk beberapa jenis masukkan tertentu.
4. Kesalahan pada gambar yang ditampilkan akan menimbulkan kesalahan pengoperasian.
5. Kelelahan yang dirasakan akibat mendekati layar secara berulang kali.
6. Jari tangan seringkali menutupi tampilan visual layar.
7.  Diperlukannya metode-metode baru dalam pemrograman perangkat halus.

Membuat LCD Biasa menjadi Layar Sentuh

Albatron Technology, salah satu produsen komponen dan perangkat komputer asal Taiwan menghadirkan External Multi-touch Module EM215. Perangkat EM215 mengadopsi teknologi optik dan kompatibel dengan fitur sentuh milik Windows. Dengan demikian, pengguna bisa menginstalasikan EM215 dengan mudah, hanya dengan menancapkannya ke port USB.

“Windows 7 mendukung teknologi sentuh, akan tetapi sebagian besar pengguna tak bisa menikmatinya kecuali mereka membeli PC atau monitor yang mendukung layar sentuh,” kata juru bicara Albatron, pada keterangannya, 20 Mei 2010.

Albatron menyebutkan, dengan menggantungkan EM215 yang tebalnya hanya 1,9 milimeter pada monitor LCD yang dimiliki pengguna, mereka bisa mengupgrade layar LCD mereka menjadi layar sentuh dengan mudah.

EM215 sendiri merupakan modul layar sentuh eksternal yang didesain untuk monitor LCD ukuran 21,5 inci dengan aspek rasio 16:9. Meski demikian, Albatron mengklaim alat tambahan ini juga kompatibel dengan monitor 16:9 atau 4:3 lain yang memiliki ukuran tampilan di bawah 478x269 milimeter.

Hadir tanpa perangkat ataupun driver tambahan, di Windows 7 alat ini mendukung multi-touch. Adapun di Windows XP dan Vista, hanya mendukung single-touch. Kalibrasi sendiri tersedia secara default, pengguna sudah tidak perlu mengatur setting kalibrasi sentuh.

Pengguna bisa menggunakan jari, ballpoint, atau penggaris sebagai alat sentuh. Pada perangkat ini, Albatron juga sudah menyediakan lapisan anti gores. Saat beroperasi, EM215 hanya membutuhkan daya kurang dari 1 watt saja.

Sumber :http://teknologi.news.viva.co.id/news/read/152238-albatron_bikin_lcd_biasa_jadi_layar_sentuh

Tips Merawat Touch Screen

Touch screen atau layar sentur membutuhkan perawatan khusus agar layar tersebut tetap awet dan tahan lama. Peralatan seperti HP Touchscreen, Monitor Touchscreen tentunya membutuhkan  cara-cara tertentu untuk melindungi bagian layar. Berikut ini tips cara merawat touch screen.

1. Gunakan screen protector atau plastik antigores pada layar.
2. Tidak menggunakan kuku untuk mengusap layar.
3. Gunakan jari telunjuk untuk menggunakan layar.
4. Hidari meletakkan peralatan touch screen pada tempat yang sempit atau menekan (seperti pada saku celana jeans).
5. Hidari dari sinar matahari langsung.
6. Jangan menekan layar terlalu kencang, gunakan sewajarnya saja.
7. Hidari dari benda-benda tajam dan keras yang dapat menggores atau merusak layar touchscreen.

Technology of Touch Screen

There are a variety of touchscreen technologies that have different methods of sensing touch.

    Resistive
    Surface acoustic wave
    Capacitive
    Infrared
    Optical imaging
    Dispersive signal technology
    Acoustic pulse recognition

1. Resistive

A resistive touchscreen panel comprises several layers, the most important of which are two thin, transparent electrically-resistive layers separated by a thin space. These layers face each other, with a thin gap between.The top screen (the screen that is touched) has a coating on the underside surface of the screen. Just beneath it is a similar resistive layer on top of its substrate. One layer has conductive connections along its sides, the other along top and bottom. A voltage is passed through one layer, and sensed at the other. When an object, such as a fingertip or stylus tip, presses down on the outer surface, the two layers touch to become connected at that point: The panel then behaves as a pair of voltage dividers, one axis at a time. By rapidly switching between each layer, the position of a pressure on the screen can be read.

Resistive touch is used in restaurants, factories and hospitals due to its high resistance to liquids and contaminants. A major benefit of resistive touch technology is its low cost. Disadvantages include the need to press down, and a risk of damage by sharp objects. Resistive touchscreens also suffer from poorer contrast, due to having additional reflections from the extra layer of material placed over the screen.[citation needed]

2. Surface acoustic wave

Surface acoustic wave (SAW) technology uses ultrasonic waves that pass over the touchscreen panel. When the panel is touched, a portion of the wave is absorbed. This change in the ultrasonic waves registers the position of the touch event and sends this information to the controller for processing. Surface wave touchscreen panels can be damaged by outside elements. Contaminants on the surface can also interfere with the functionality of the touchscreen.

3. Capacitive

A capacitive touchscreen panel consists of an insulator such as glass, coated with a transparent conductor such as indium tin oxide (ITO). As the human body is also an electrical conductor, touching the surface of the screen results in a distortion of the screen's electrostatic field, measurable as a change in capacitance. Different technologies may be used to determine the location of the touch. The location is then sent to the controller for processing. Unlike a resistive touchscreen, one cannot use a capacitive touchscreen through most types of electrically insulating material, such as gloves; one requires a special capacitive stylus, or a special-application glove with an embroidered patch of conductive thread passing through it and contacting the user's fingertip. This disadvantage especially affects usability in consumer electronics, such as touch tablet PCs and capacitive smartphones in cold weather. In response, there are gloves on the market with one or more fingertips that include conductive material, thus overcoming this limitation. The largest capacitive display manufacturers continue to develop thinner and more accurate touchscreens, with LCD touchscreens for mobile devices now being produced with 'in-cell' technology that eliminates a layer, such as Samsungs Super AMOLED screens, by building the capacitors inside the LCD itself. This type of touchscreen reduces the visible distance (within millimetres) between the user's finger and what the user is touching on the screen, creating a more direct contact with the content displayed and enabling taps and gestures to be even more responsive.

3.1 Surface capacitance

In this basic technology, only one side of the insulator is coated with a conductive layer. A small voltage is applied to the layer, resulting in a uniform electrostatic field. When a conductor, such as a human finger, touches the uncoated surface, a capacitor is dynamically formed. The sensor's controller can determine the location of the touch indirectly from the change in the capacitance as measured from the four corners of the panel. As it has no moving parts, it is moderately durable but has limited resolution, is prone to false signals from parasitic capacitive coupling, and needs calibration during manufacture. It is therefore most often used in simple applications such as industrial controls and kiosks.

3.2 Projected capacitance

Back side of a Multitouch Globe, based on Projected Capacitive Touch (PCT) technology.

Projected Capacitive Touch (PCT; also PCAP) technology is a variant of capacitive touch technology. All PCT touch screens are made up of a matrix of rows and columns of conductive material, layered on sheets of glass. This can be done either by etching a single conductive layer to form a grid pattern of electrodes, or by etching two separate, perpendicular layers of conductive material with parallel lines or tracks to form a grid. Voltage applied to this grid creates a uniform electrostatic field, which can be measured. When a conductive object, such as a finger, comes into contact with a PCT panel, it distorts the local electrostatic field at that point. This is measurable as a change in capacitance. If a finger bridges the gap between two of the "tracks," the charge field is further interrupted and detected by the controller. The capacitance can be changed and measured at every individual point on the grid (intersection). Therefore, this system is able to accurately track touches.[20] Due to the top layer of a PCT being glass, it is a more robust solution than less costly resistive touch technology. Additionally, unlike traditional capacitive touch technology, it is possible for a PCT system to sense a passive stylus or gloved fingers. However, moisture on the surface of the panel, high humidity, or collected dust can interfere with the performance of a PCT system. There are two types of PCT: mutual capacitance and self-capacitance.

3.2.1 Mutual capacitance

This is common PCT approach, which makes use of the fact that most conductive objects are able to hold a charge if they are very close together. In mutual capacitive sensors, there is a capacitor at every intersection of each row and each column. A 16-by-14 array, for example, would have 224 independent capacitors. A voltage is applied to the rows or columns. Bringing a finger or conductive stylus close to the surface of the sensor changes the local electrostatic field which reduces the mutual capacitance. The capacitance change at every individual point on the grid can be measured to accurately determine the touch location by measuring the voltage in the other axis. Mutual capacitance allows multi-touch operation where multiple fingers, palms or styli can be accurately tracked at the same time.

3.2.2 Self-capacitance

Self-capacitance sensors can have the same X-Y grid as mutual capacitance sensors, but the columns and rows operate independently. With self-capacitance, the capacitive load of a finger is measured on each column or row electrode by a current meter. This method produces a stronger signal than mutual capacitance, but it is unable to resolve accurately more than one finger, which results in "ghosting", or misplaced location sensing.

4. Infrared

Infrared sensors mounted around the display watch for a user's touchscreen input on this PLATO V terminal in 1981. The monochromatic plasma display's characteristic orange glow is illustrated. An infrared touchscreen uses an array of X-Y infrared LED and photodetector pairs around the edges of the screen to detect a disruption in the pattern of LED beams. These LED beams cross each other in vertical and horizontal patterns. This helps the sensors pick up the exact location of the touch. A major benefit of such a system is that it can detect essentially any input including a finger, gloved finger, stylus or pen. It is generally used in outdoor applications and point of sale systems which can not rely on a conductor (such as a bare finger) to activate the touchscreen. Unlike capacitive touchscreens, infrared touchscreens do not require any patterning on the glass which increases durability and optical clarity of the overall system. Infrared touchscreens are sensitive to dirt/dust that can interfere with the IR beams, and suffer from parallax in curved surfaces and accidental press when the user hovers his/her finger over the screen while searching for the item to be selected.

5. Optical imaging

Optical touchscreens are a relatively modern development in touchscreen technology, in which two or more image sensors are placed around the edges (mostly the corners) of the screen. Infrared back lights are placed in the camera's field of view on the other side of the screen. A touch shows up as a shadow and each pair of cameras can then be pinpointed to locate the touch or even measure the size of the touching object (see visual hull). This technology is growing in popularity, due to its scalability, versatility, and affordability, especially for larger units.

6. Dispersive signal technology

Introduced in 2002 by 3M, this system uses sensors to detect the piezoelectricity in the glass that occurs due to a touch. Complex algorithms then interpret this information and provide the actual location of the touch. The technology claims to be unaffected by dust and other outside elements, including scratches. Since there is no need for additional elements on screen, it also claims to provide excellent optical clarity. Also, since mechanical vibrations are used to detect a touch event, any object can be used to generate these events, including fingers and stylus. A downside is that after the initial touch the system cannot detect a motionless finger.

7. Acoustic pulse recognition

In this system, introduced by Tyco International's Elo division in 2006, the key to the invention is that a touch at each position on the glass generates a unique sound. Four tiny transducers attached to the edges of the touchscreen glass pick up the sound of the touch. The sound is then digitized by the controller and compared to a list of prerecorded sounds for every position on the glass. The cursor position is instantly updated to the touch location. APR is designed to ignore extraneous and ambient sounds, since they do not match a stored sound profile. APR differs from other attempts to recognize the position of touch with transducers or microphones, in using a simple table lookup method rather than requiring powerful and expensive signal processing hardware to attempt to calculate the touch location without any references. The touchscreen itself is made of ordinary glass, giving it good durability and optical clarity. It is usually able to function with scratches and dust on the screen with good accuracy. The technology is also well suited to displays that are physically larger. Similar to the dispersive signal technology system, after the initial touch, a motionless finger cannot be detected. However, for the same reason, the touch recognition is not disrupted by any resting objects.

Introducing of Touch Screen

A touchscreen is an electronic visual display that can detect the presence and location of a touch within the display area. The term generally refers to touching the display of the device with a finger or hand. Touchscreens can also sense other passive objects, such as a stylus. Touchscreens are common in devices such as game consoles, all-in-one computers, tablet computers, and smartphones.

The touchscreen has two main attributes. First, it enables one to interact directly with what is displayed, rather than indirectly with a pointer controlled by a mouse or touchpad. Secondly, it lets one do so without requiring any intermediate device that would need to be held in the hand (other than a stylus, which is optional for most modern touchscreens). Such displays can be attached to computers, or to networks as terminals. They also play a prominent role in the design of digital appliances such as the personal digital assistant (PDA), satellite navigation devices, mobile phones, and video games.

The popularity of smartphones, tablet computers and many types of information appliances is driving the demand and acceptance of common touchscreens for portable and functional electronics. With a display of a simple smooth surface, and direct interaction without any hardware (keyboard or mouse) between the user and content, fewer accessories are required. Touchscreens are popular in the medical field, and in heavy industry, as well as kiosks such as museum displays or room automation, where keyboard and mouse systems do not allow a suitably intuitive, rapid, or accurate interaction by the user with the display's content.

Historically, the touchscreen sensor and its accompanying controller-based firmware have been made available by a wide array of after-market system integrators, and not by display, chip, or motherboard manufacturers. Display manufacturers and chip manufacturers worldwide have acknowledged the trend toward acceptance of touchscreens as a highly desirable user interface component and have begun to integrate touchscreens into the fundamental design of their products.

History of Touch Screen

E.A. Johnson described his work on capacitive touch screens in a short article published in 1965 and then more fully—along with photographs and diagrams—in an article published in 1967. A description of the applicability of the touch technology for air traffic control was described in an article published in 1968. Bent Stumpe with the aid of Frank Beck, both engineers from CERN, developed a transparent touch screen in the early 1970s and it was manufactured by CERN and put to use in 1973. This touchscreen was based on Bent Stumpe's work at a television factory in the early 1960s. A resistive touch screen was developed by American inventor G Samuel Hurst and the first version produced in 1982.

From 1979–1985, the Fairlight CMI (and Fairlight CMI IIx) was a high-end musical sampling and re-synthesis workstation that utilized light pen technology, with which the user could allocate and manipulate sample and synthesis data, as well as access different menus within its OS by touching the screen with the light pen. The later Fairlight series IIT models used a graphics tablet in place of the light pen. The HP-150 from 1983 was one of the world's earliest commercial touchscreen computers. Similar to the PLATO IV system, the touch technology used employed infrared transmitters and receivers mounted around the bezel of its 9" Sony Cathode Ray Tube (CRT), which detected the position of any non-transparent object on the screen.

Six images of General Motors' ECC (Electronic Control Center), released in 1985 as the first touchscreen included as standard equipment in a production automobile. The CRT-based ECC first debuted on the 1986 Buick Riviera as the primary interface used to operate and monitor the vehicle's climate and stereo systems.

In the early 1980s General Motors tasked its Delco Electronics division with a project aimed at replacing an automobile's non essential functions (i.e. other than throttle, transmission, braking and steering) from mechanical or electro-mechanical systems with solid state alternatives wherever possible. The finished device was dubbed the ECC for "Electronic Control Center", a digital computer and software control system hardwired to various peripheral sensors, servos, solenoids, antenna and a monochrome CRT touchscreen that functioned both as display and sole method of input. The EEC replaced the traditional mechanical stereo, fan, heater and air conditioner controls and displays, and was capable of providing very detailed and specific information about the vehicles cumulative and current operating status in real time. The ECC was standard equipment on the 1985-1989 Buick Riviera and later the 1988-89 Buick Reatta, but was unpopular with consumers partly due to technophobia on behalf of some traditional Buick customers, but mostly because of costly to repair technical problems suffered by the ECC's touchscreen which being the sole access method, would render climate control or stereo operation impossible.

In 1986 the first graphical point of sale software was demonstrated on the 16-bit Atari 520ST color computer. It featured a color touchscreen widget-driven interface. The ViewTouchpoint of sale software was first shown by its developer, Gene Mosher, at Fall Comdex, 1986, in Las Vegas, Nevada to visitors at the Atari Computer demonstration area and was the first commercially available POS system with a widget-driven color graphic touch screen interface.

An early attempt at a handheld game console with touchscreen controls was Sega's intended successor to the Game Gear, though the device was ultimately shelved and never released due to the expensive cost of touchscreen technology in the early 1990s. Touchscreens would not be popularly used for video games until the release of the Nintendo DS in 2004. Until recently, most consumer touchscreens could only sense one point of contact at a time, and few have had the capability to sense how hard one is touching. This has changed with the commercialization of multi-touch technology.