Touch Screens: A Pressing Technology

More documents

Recommendations

Info

1118 B9 and emitters are much smaller and would cover a much smaller area of the screen. Traditional internal reflection system only required four or five emitters and cameras. Thinsight technology is still in development; however, it is believed that these advancements could make infrared touch screen technology much smaller. The advancements would also cause the system to be more available for future consumer touch screen devices. FIGURE 1 THINSIGHT TOUCH SCREEN INFRARED EMITTERS AND DETECTORS [5] Microsoft Surface As mentioned above, the Microsoft Surface is a great example of internal reflection infrared touch screens. In early 2001, “Steve Bathiche of Microsoft Hardware and Andy Wilson of Microsoft Research began brainstorming concepts for an interactive table”, beginning the development of the Surface [6]. The process continued in development until 2003 when the idea was presented to Bill Gates, and 85 prototypes were created for developers on the Surface Computing group, a group created in 2004 to solely develop the Surface. In 2005, various prototypes were created and analyzed, and eventually, in 2008, the Microsoft Surface was on sale to the public for $12,500 or $15,000 [6]. The Surface’s “technology uses multiple image sensors around one side of the touch surface and IR backlights on the other side. When a user places his finger on the surface, intercepting the infrared beam, the device projects a shadow. Using multiple cameras, the unit converts this shadow into a touch point through triangulation” [3]. As stated by Dr. Hsu, the Surface uses a system of cameras and IR LED’s to capture the image of the object touching the surface. The Surface took a step forward with their technology, developing a special motherboard to compute the data, transmitted at 100 megabytes per second, from the cameras. The board then divides the data into sections that decide what is relevant and what is not. Relevant data is considered to be any information from the cameras that has changed since the last transmission. An example of that is the shadow from the infrared light changing as someone touches the screen. This software is also revolutionary in that it detects and distinguishes different types of touches. The Surface categorizes touches into three sets: finger, blob, and tagged objects. Fingers are given the ability to click on software application buttons, paint across the screen, and further interact with the Surface. Blobs are generic objects that are given a circular or oval reading with a major and minor axis. Blobs include inanimate objects like paper or other pieces of technology like smart phones or cameras [7]. Microsoft products, like the Microsoft Zune music player, can interact with the Surface just by laying Zune upon the top of the screen. Multiple Zunes can interact with one another using the Surface as an intermediary, transferring songs from one to another. Cameras and phones can also perform similar tasks with contacts, pictures, maps, and many other pieces of data. Microsoft has been “initially selling Surface to Starwood Hotels for guest check in, Harrah’s Entertainment for video gambling, and T-Mobile for providing customers with technical information about the company’s mobile phones” [4]. The Surface allows for the use of tagged items, specific to where the device is located. Tagged items could include gambling chips at a Harrah’s Casino or an electric keycard at a Starwood Hotel. The tagged items give the Surface very specific data, which includes the facing direction of the object as well as electric data on the tagged item itself [7]. FIGURE 2 MICROSOFT SURFACE [6] Through previous advances in touch screen technology, Microsoft took a step forward in infrared systems with their Surface. The Surface’s starting price is $12,500. This high cost makes the Surface inaccessible to personal consumers, and is therefore marketed toward corporations or companies. RESISTIVE TOUCH SCREENS Resistive touch screen systems are the most common type of touch screen technology in today’s market. These devices are used in many applications, such as cell phones, handheld games, GPS navigation devices, and even some digital cameras [3]. The resistive touch screen technology operates in a very simple way. These screens are built using two layers of the conductive material Indium Tin Oxide (ITO), separated University of Pittsburgh April 10, 2010 TENTH ANNUAL FRESHMAN CONFERENCE 2
1118 B9 by a small gap of air [3]. The bottom layer is generally on glass, and the top on a flexible material, often plastic [8]. When the user presses down on the top ITO layer, it physically bends to make contact with the bottom ITO layer, changing the resistance of the two layers [8]. A typical resistive touch screen uses 4 wires, 2 of them on each panel. As seen in Figure 3, each panel corresponds to a different axis. These perpendicular axes allow the computer to take the measurements of the change in resistance from each panel, and calculate the position of the touch point from its X and Y components [3]. due to the slight electromagnetic charge contained in the human body [8]. These changes in capacitance are measured and calculated as touch points in a very similar way to resistive touch screens, by using the X and Y components. FIGURE 4 PROJECTED CAPACITIVE TOUCH SCREEN LAYERS [8] FIGURE 3 TYPICAL 4-WIRE RESISTIVE TOUCH SCREEN [3] CAPACITIVE TOUCH SCREENS Capacitive touch screens are very important within the field of touch screen technology. In the early 1990s, this technology made its initial appearance into the touch screen market in laptop computers, as touch pads [3]. Recently, capacitive popularity has grown, as it has become one of the leading technologies used in touch screen devices. In 2001, it began appearing in consumer devices, such as MP3- players and smart phones [3]. This increase in attention is likely due to the effectiveness of its design, its use of multitouch technology, and the popularity of Apple products using this technology: iPod Touch, iPhone and most recently the iPad. [9]. Projected Capacitive Touch Screens The design of projected capacitive touch screens is somewhat similar to that of resistive touch screens, in that they both utilize 2 layers of ITO, with perpendicular conductive measuring strips on the ends of each layer [8], which are encased between two glass layers (See Figure 4). This “grid,” formed by the perpendicular conductive layers, projects the electric field through the top layer of glasshence the name projected capacitive touch screens [8]. Because of this projection, when the user touches the top layer of glass it “changes the measured capacitance values of the electrodes closest to it” [3]. This change in capacitance is Surface Capacitive Touch Screens Surface capacitive is another form of capacitive touch screen technology. The primary difference between surface capacitive and projected capacitive is that surface capacitive uses only one ITO surface [3]. This layer calculates touch points using principles that are very similar to projected capacitive touch screens, in that touch points are observed by changes in capacitance if the ITO layer in the touch screen. However, these touch points are measured in a very different way. The computer measures the change in capacitance from each corner of the ITO layer, and with these 4 separate measurements, the X and Y coordinates of the touch point are calculated [3]. Multi-Touch Technology An important feature of capacitive touch screens is their ability to recognize and calculate multiple touch points at one time, commonly called multi-touch. “Multi-touch technology has been around since early research at the University of Toronto in 1982” [4]. The uses of this technology are very vast, allowing for greater humancomputer interaction. This technology is traditionally associated with capacitive touch screens, but is not limited to this technology. It can also be found in infrared touch screens and is beginning to appear in resistive touch screens [3]. Currently, multi-touch technology is being used with a purpose similar to the function keys (Control, Alt, Option, Command, etc.) on a standard keyboard. By adopting these functions, the user is able to complete the same tasks as before, but with one hand. With advances in hardware, multi touch will allow multiple users to access the same device simultaneously, like the Microsoft Surface’s capability of 300 plus touches. While the hardware is available to create such devices, software implementation is holding back the growth of multi touch. University of Pittsburgh April 10, 2010 TENTH ANNUAL FRESHMAN CONFERENCE 3
Page 1: 1118 B9 TOUCH SCREENS: A PRESSING T
Page 5 and 6: 1118 B9 Capacitive touch screens ar

Touch Screens: A Pressing Technology

Create successful ePaper yourself

Delete template?

Save as template?